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NANO-FUNCTIONAL MATERIALS

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Synthesis, processing and characterization of nanoscale multi functional oxide films VII

Good control of oxide films thickness, composition and structure offers the possibility to integrate in heterostructures new functionalities. Progress in synthesis, processing and characterization of multifunctional oxide films plays a key role for the development of new devices, from microelectronics to energy and environment applications.

Scope:

Oxides can present a vast range of functional tunable properties, such as ferroelectricity, ferromagnetism, multiferroicity, electrical conductivity, superconductivity, thermoelectricity, optical transparency, catalytic behavior, high temperature barriers, or thermochemical protection among others. These properties can lead to innovative applications, which in many cases will require thin films with controlled properties suitable to offer high performance devices.

The functional properties of the oxides are extremely dependent on changes in the crystal structure, composition, and defects. The complexity of oxides and the relevance of their microstructure on the properties make the deposition of thin films critical. The control of thin films growth, coupled with accurate characterization tools for structure, composition and properties, modeling, and theoretical understanding, are prerequisites for further development of new high performance oxide-based materials for device applications. In this respect, the effects of strain, interfaces, defects, composition and doping, which are key parameters allowing the tuning of properties must be fully understood at the microscopic as well as at the macroscopic level. Interface phenomena between oxides but also between oxides and other materials, are also relevant as new properties can emerge. In concert with sustainable development, the avoidance of polluting, toxic, or scarce chemical elements is another major technological objective. Moreover, many applications require the use of low cost deposition methods while others require the integration of the oxides on suitable platforms, such as semiconducting wafers or flexible substrates.

This symposium follows a series of six very successful and well attended E-MRS symposia organized from 2006 to 2017. The symposium intends to continue the established tradition of an interdisciplinary forum that will bring together scientists involved in various aspects of the synthesis, processing characterization, device integration and theoretical modeling of multi-functional oxide-based thin films, multilayers and nanostructures to discuss the latest developments and future trends and challenges.

Hot topics to be covered by the symposium:

  • Growth of oxide thin films by physical & chemical methods, including advanced & novel techniques.
  • Growth and properties of complex heterostructures, including superlattices
  • Growth and properties of nanocomposite or hybrid oxide based thin films
  • Integration of oxides on semiconductors
  • Oxide nanosheets, & films on flexible substrates
  • Epitaxial stabilization of metastable phases
  • Defects in oxide thin films and at interfaces
  • In situ characterization of oxide film growth
  • Advanced characterization by microscopies & spectroscopic techniques
  • Ferroelectric, ferromagnetic, & multiferroic oxides
  • Oxide films for energy generation & conservation
  • Transparent conducting oxides

Invited presentations

  • Wilfrid Prellier, CRISMAT, Caen, France: "Growth of oxide films using combinatorial substrate epitaxy"
  • Emmanuel Defay, LIST, Luxembourg: "Inkjet printed transparent piezoelectric thin films for transducers on glass"
  • Johan E. ten Elshof, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands: "2D metal oxide nanosheets: synthesis and applications in advanced electronic materials"
  • Magdalena Nistor, NILPRP, Magurele-Bucharest, Romania: "Oxide thin films by pulsed electron beam deposition: growth and properties"
  • Bénédicte Warot-Fonrose, CEMES-CNRS, Toulouse, France: "Quantitative electron microscopy on oxides : local strain and chemistry mapping"
  • Ying Hao Chu, Natl Chiao Tung Univ, Taiwan: "Growth of van der Waals oxide heteroepitaxy for transport soft electronics"
  • Francisco Rivadulla, Univ. de Santiago de Compostela, Spain: "Growth of epitaxial oxides by chemical and physical methods: impact on the structural and magnetic properties"
  • Elvira Fortunato, Univ Nova Lisboa, Portugal: TBA
  • Uwe Schroeder, NaMLab gGmbH, Germany: "Impact of deposition process parameters on the ferroelectric properties of doped hafnia films"
  • Robert Hoye, University of Cambridge, UK: "Rapid growth of oxides onto perovskite solar cells through chemical vapour deposition for improved performance and mechanical protection"
  • C. Himcinschi, Germany: "Raman spectroscopy as a versatile tool for complex oxides characterisation: from ferroelastic domain wall tilting to orbital ordering"
  • Fabio Miletto Granozio, Italy: "Tayloring the properties of 2D electron gases at oxide interfaces by atomic engineering of epitaxial growth"
  • A Klein, Germany, Darmstadt University, Germany: "Limits of the Fermi energy in oxides"
  • Zhong Lin (Z.L.) Wang, Georgia Institute of Technology, USA: "Oxide based piezotronics"

Publication:

Selected papers will be published in a Special Issue of Thin Solid Films (Elsevier).

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Semiconducting oxides : -
10:30
Authors : Elvira Fortunato
Affiliations : i3N/CENIMAT, Department of Materials Science from Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal

Resume : After the huge success and revolution of transparent electronics and with the worldwide interest in displays where metal oxide thin films (MOTF) have proved to be truly semiconductors, display backplanes have already gone commercial due to the huge investment of several high profile companies: SHARP, SAMSUNG, LG, BOE. Recently IDTechEx estimated that 8 km sqr of MOTF backplanes will be used in the OLED and LCD industry by 2024, enabling a 16 billion USD market at the display module level alone. Currently, semiconductor technology combines two very different and often incompatible materials leading to sub-optimal properties, namely simple semiconductors and oxides. The former (Si, Ge) are essential for efficient carrier transport, while the latter enable various functionalities. The challenge of the proposed work is to develop MOTF and TFTs with properties comparable to those of the simple semiconductors. In addition, the properties of many MO have never been explored. It is notable that MO provide a unique possibility to tune optical and electronic properties, from insulation to metallic conduction; besides that MO are chemically stable, mostly non-toxic and abundant materials, often manufactured by low cost methods, under ambient conditions. Consequently, devices made of MO are inexpensive, very stable and environmentally safe, the 3 most important requirements for electronics. In this talk we will present results on recent new technologies developed at CENIMAT|i3N like tr

O.1.1
11:00
Authors : Viet Huong Nguyen, Ulrich Gottlieb, Anthony Valla, Bruno Masenelli, Delfina Muñoz, Daniel Bellet, David Muñoz-Rojas
Affiliations : Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France. Univ. Grenoble Alpes, CEA, LITEN, INES, 73375 Le Bourget-du-Lac, France Institut des Nanotechnologies de Lyon, INL, CNRS-UMR5270, INSA-Lyon, 69622 Villeurbanne, France

Resume : Transparent conductive oxides (TCOs) are key components of optoelectronic devices, such as solar cells or LEDs. TCOs, and in general all highly doped polycrystalline semiconductors, present high potential barriers and short depletion layers at the grain boundaries. This results in an increased probability of electron tunnelling through the grain boundaries, as opposed to the thermionic emission mechanism observed in low doping semiconductors. Existing conductivity models do not properly account for charge tunnelling through the grain boundaries in TCOs, which prevents a proper understanding of the scattering mechanisms limiting their conductivity. We present a new model based on the Airy Function Transfer Matrix Method that allows the numerical calculation of charge mobility through grain boundaries in highly doped polycrystalline semiconductors. The new model has been used to fit experimental data obtained for Aluminum doped ZnO (ZnO:Al) samples synthesized by different methods. This has allowed the calculation of the electron trap density at grain boundaries, thus providing the dominant charge scattering mechanisms for the different samples. Our findings help to understand fundamental electrical transport mechanisms in TCOs and provide guidance on how to optimize the deposition conditions. For example, we show that ZnO:Al thin films processed in the open air using atmospheric pressure spatial atomic layer deposition contain a high trap density at the grain boundaries due to trapping of oxygen species during deposition. WE show that a simple UV treatment can enhance the conductivity of such films thanks to the light-induced de-trapping of the O species at the grain boundaries.

O.1.2
11:15
Authors : Sebastian C. Dixon[1], Hidenori Hiramatsu[2], Hideo Hosono[2], Claire J. Carmalt[1], Ivan P. Parkin[1]
Affiliations : [1] Materials Chemistry Centre, University College London, 20 Gordon Street, London WC1H OAJ, UK; [2] Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan

Resume : While Sn-doped In2O3 (ITO) remains the leading TCO material for the majority of optoelectronic applications, strong hybridization between the Sn and In 5s states close to the conduction band minimum (CBM) reduces conduction band curvature, limiting charge carrier mobility and therefore electrical conductivity. Recently, new understanding of the behaviour of transition metal (TM) doping of In2O3 has revealed a mechanism in which charge carriers are injected into the CBM from TM d-orbital states higher above the CBM, minimising orbital hybridization close to the CBM and therefore enabling significantly higher carrier mobility to be achieved. The most conspicuous example is Mo-doped In2O3, which has already demonstrated a manifold increase in electron mobility over ITO due to this effect, though Zr- and Hf-doping have also emerged as high-mobility alternatives to ITO in single-crystal studies. This work represents an experimental-computational collaboration in which high-purity Mo-, Zr-, Hf- and Sn-doped polycrystalline In2O3 have been deposited by RF magnetron sputtering in order to elucidate the effect of dopant selection on conduction band curvature, film transparency and intergrain barrier height in polycrystalline materials.

O.1.3
11:30
Authors : H. Kröncke 1*, M. Rusu 1, S. Wiesner 1, N. Maticiuc 1, I. Lauermann 1, V. Deshpande 1, C. Dubourdieu 1,2
Affiliations : 1 Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany 2 Freie Universität Berlin, Institut für Chemie und Biochemie, Berlin, Germany

Resume : Gallium oxide, as a high band-gap semiconductor, is a good candidate for various applications such as high-temperature and ultra-high-voltage electronics, photon detectors, gas sensors as well as thin tunneling barriers in various devices. We report the growth of amorphous gallium oxide by plasma-assisted atomic layer deposition on (100) silicon substrates up to 200mm diameter from trimethylgallium precursor and dioxygen. The effect of surface treatments prior to deposition and of various processing parameters on the amorphous deposited films were investigated using in situ spectroscopic ellipsometry and will be discussed. In the temperature range of 150-250 °C, the growth rate is of ~0.65 Å/cycle. The thickness variation over 200 mm wafers is found to be of 1.4% and the refractive index change of 0.2% as determined from spectroscopic ellipsometry mappings. The rms roughness is within the detection limit of the atomic force microscope (~0.2nm). By annealing in a furnace or by rapid thermal processing up to 1000°C, the layers crystallize in the monoclinic β-Ga2O3 phase at the cost of an increased roughness. X-ray photoelectron spectroscopy indicates an increased state of oxidation for Ga. The electrical characterization of the amorphous and crystalline films through CVs (on MOS capacitors) and IVs will be discussed.

O.1.4
11:45
Authors : Thomas J. Featherstone(1), Benjamin A. D. Williamson(2,3), Sanjayan S.Sathasivam (4), Jack E. N. Swallow(1), Huw Shiel(1), Leanne A. H. Jones(1), Matthew J.Smiles(1), Anna Regoutz(5), Tien-Lin Lee(6), David A. Duncan(6), Pardeep Kumar Thakur(6), Vin R. Dhanak(1), Claire J. Carmalt(4), Ivan P. Parkin(4), Tim D. Veal(1), and David O. Scanlon(2,3,6)
Affiliations : (1)-Stephenson Institute for Renewable Energy and Department of Physics,University of Liverpool, Liverpool, L69 7ZF, UK (2)-Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK (3)-Thomas Young Centre, University College London, Gower Street, London, WC1E 6BT, UK (4)-Materials Research Centre, Chemistry Department, University College London,WC1H 0AJ, UK (5)-Department of Materials, Imperial College London, London SW7 2AZ, Uk (6)-Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK

Resume : Traditionally SnO_2 has been doped with F or Sb to make it conducting and suitable for applications requiring transparent electrodes [1,2]. However, the maximum achievable conductivity using these dopants has been shown to be limited due to mobilities significantly below the theoretical limit [3]. Ta doped SnO_2 is a promising alternative to Sb cation doping of SnO_2. Here, we deposit Ta-doped SnO_2 by aerosol assisted chemical vapor deposition with mobilities of up to 26 cm^2V^?1s^?1 for carrier concentrations of greater than 2×10^20cm^?3. Sb-doped SnO^2 deposited by the same method displays mobilities of less than 18 cm^2V^-1s^-1 for similar carrier concentrations. We use Density Functional Theory (DFT) calculations to probe the different electronic structures of the two materials. Hard x-ray photoemission spectroscopy is used to determine differences in conduction band filling, relating to electronic structures of the two systems. Modelling of this data indicates that the band edge effective mass is higher for Sb doping than for Ta doping. This supports that Ta 5d states mix minimally with the SnO_2 conduction band minimum compared with Sb 5s states, in agreement with the DFT results. This explains the increase in mobility seen for Ta doping over Sb and show a potential route to high conductivity SnO_2 based TCOs. [1]- J. Mater. Chem. C, 2016, 4,6946 [2]- Thin Solid Films, 2017, 624, 152?159 [3]- Adv. Funct. Mater, 2017, 28(4), 1701900

O.1.5
12:00
Authors : Hyojun Kim1, Taehyup Lim1, Sung-Hoon Ahn2 and Caroline Sunyong Lee1,†
Affiliations : 1. Department of Materials and Chemical Engineering, Hanyang University, Ansan, South Korea 2. Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul, South Korea

Resume : A metal oxide thin film has been studied widely for optoelectronic devices, photocatalyst, water splitting, and energy storage. Metal oxide synthesis method using precursors has its advantage of chemically/physically forming the desired substance. Metal oxide can be synthesized by various methods such as Hydrothermal method, Solvothermal method, and Sol-Gel method. Among them, the sol-gel method can easily synthesize thin films with its thickness of less than 100 nm with transparency. For the case of metal-oxide synthesized by this method, metal-oxide is conventionally spin-coated on a FTO (Fluorine-doped tin oxide) substrate and then heat-sintered at its temperature of 500 °C or more. This sintering at high temperature can limit its uses to be applied to flexible devices. Therefore, we have tried to solve this problem by flash light sintering process. Flash light sintering uses Xenon Flash lamp giving momentary optical pulses with Mega Watt power for high-speed sintering at room temperature. Therefore, the metal oxide synthesized by Sol-Gel method can be flash-light sintered into thin film at low temperature. In the present work, TiO2 and WO3 were synthesized by sol gel method and then fabricated into thin films by flash light sintering process. TiO2 and WO3 thin films were sintered at low temperature via flash light sintering. TiO2 and WO3 thin films prepared by thermal sintering vs. flash light sintering methods were compared using XRD for its phase formation. The microstructures of thin films were compared by SEM and TEM while its bandgap was measured using absorbance spectrometer, to confirm that the flash light sintering method can be used alternatively to fabricate transparent metal oxide film at room temperature. These transparent TiO2 and WO3 thin films can be applied to not only gas sensor, electrochromic and photocatalysis but also flexible devices.

O.1.6
12:15
Authors : Yutaka Furubayashi, Tetsuya Yamamoto
Affiliations : Research Institute, Kochi University of Technology

Resume : Tin-doped In2O3 (ITO) is widely applied to transparent conducting oxides (TCO) films. To control the carrier concentration (ne) for wide applications, most reports have focused on a chemical doping or post annealing. There have been few reports on a wide-range control of ne of ITO films after the growth in crystalline form. In this study, we have succeeded in reducing ne of polycrystalline ITO films by using our developed technology to generate and irradiate electronegative oxygen (O) ions. 50-nm-thick ITO polycrystalline films with a SnO2 content of 5 wt% were grown at 200 oC by reactive plasma deposition (RPD). The as-deposited ITO films had ne of 9 × 1020 cm-3. We carried out a post irradiation of O ions at 250 oC in the same RPD machine with an applied bias of 100 V. The process for 120 min resulted in a drastically reduction in ne down to 1 × 1019 cm-3. Note that X-ray diffraction measurements revealed that the irradiation causes almost no changes in the crystal structure. Optical measurement results yielded that an optical absorption by free carriers was completely suppressed for the O-irradiated films. This study demonstrates that the O-ions-irradiation technique is an effective way in controlling ne in a wide range while maintaining the crystal structure. This study was supported by Dr. N. Takahashi, Mr. T. Sakemi, and Mr. H. Kitami of Sumitomo Heavy Industries, Ltd. and Prof. H. Makino of Kochi University of Technology.

O.1.7
12:30 Lunch    
 
Semiconducting oxides : -
14:00
Authors : Robert L. Z. Hoye
Affiliations : University of Cambridge, UK

Resume : Tandem photovoltaics between silicon and metal-halide perovskites are a promising technology, having already reached 28% power conversion efficiency after only 5 years of development. This already exceeds the record efficiency for single-junction silicon cells. The transparent top electrode is a key component and is typically deposited by sputtering, which can damage the soft metal-halide perovskite top-cell. Recently, it has been shown that thin (<10 nm) buffer layers grown by atomic layer deposition (ALD) can protect the perovskite from sputter damage. However, an important limitation of ALD is that the thermally-sensitive metal-halide perovskite is exposed to elevated temperatures (100–150 C) for extended periods of time. In this presentation, atmospheric pressure chemical vapour deposition will be explored as a scalable alternative approach for growing buffer layer oxides. The first part of this presentation will cover the design of the AP-CVD reactor we have developed and how it enables a range of binary and multicomponent n-type and p-type oxides to be grown with the same quality and growth temperature as ALD, but two orders of magnitude faster [1]. The second part of the talk will cover our recent work investigating the use of AP-CVD to grow n-type oxides over thermally-sensitive perovskites as sputter buffer layers. We show that we can utilise the benefits of rapid growth without sacrificing the pinhole-free, conformal nature of the oxides grown, which allows us to avoid perovskite degradation and improve the efficiencies of our single-junction devices to 19.7%. The results of interface studies through photoemission spectroscopy and time-resolved photoluminescence will be discussed, along with the electronic, optical and mechanical properties of the oxides grown. [1] R.L.Z. Hoye, et al., ACS Appl. Mater. Interfaces, 7, 10684 (2015)

O.2.1
14:30
Authors : C. Tenailleau, G. Salek, T.L. Le, S. Guillemet-Fritsch
Affiliations : CIRIMAT, CNRS-INP-UPS, Université de Toulouse, France

Resume : Solar energy conversion to electricity is indeed a good alternative to fossil fuels which are non-renewable resources and contaminants for the environment. Among the few light-absorber and semiconducting materials used for making photovoltaics, silicon is still the most commonly commercialized not only thanks to its conversion efficiency but also to its non-toxicity and large natural abundance, despite an indirect band gap, costing process of purification and less flexible systems. The next generation of photovoltaics could be entirely based on nanostructured or superimposed thin layers of transparent and absorber conducting metal oxides. While the former n-type of semiconducting oxides is well reported (ZnO, ITO, TiO2 for TCOs) the latter is often limited to p-type Cu2O. However, the quantum yield for Cu2O is yet to be improved with 6% conversion efficiency measured in the best case compared to the theoretical value (~20%). Our new preparation method of Light absorber oxide materials, i.e. Cu2O and MM’2O4 (M,M’=Co,Mn,Cu…), will be detailed [G. Salek et al., Mat. Chem. Phys., 162, 252 (2015) & Thin Solid Films, 589, 872 (2015); C. Tenailleau et al., Mater. Renew. Sustain. Energy, 6, 1-7 (2017)]. This low-cost synthetic method of oxide nanoparticles developed under ambient atmosphere is free of complex organic agents or surfactants. As-obtained colloidal suspensions are used for preparing homogenous crystalline oxide thin films on glass, quartz or metal substrates by the dip-coating technique. Finally, photovoltaic systems based on newly developed and very promising Light absorber oxide and hybrid materials of perovskite structural type will be discussed.

O.2.2
14:45
Authors : Emanuel Carlos*, Rita Branquinho*, Asal Kiazadeh*, Pedro Barquinha*, Nikolaos Kalfagiannis**, Demosthenes C. Koutsogeorgis**, Asko Sneck***, Jaakko Leppäniemi***, Ari Alastalo***, Rodrigo Martins* and Elvira Fortunato*
Affiliations : *i3N/CENIMAT, Department of Materials Science, Faculty of Sciences and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal; **School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK; ***VTT Technical Research Centre of Finland Ltd., Tietotie 3, Espoo FI-02150, Finland;

Resume : Progress in low-cost processing technologies and large-area manufacturing have enabled further progress in flexible electronics. Nevertheless, to achieve the same performance at low temperature than physical methods, solution combustion synthesis (SCS) and ultraviolet (UV) post-deposition treatment have been essential. The combination of these methods improves the reliability of the nanoscale film morphology, composition of metal oxides and stability over time. However, to fulfil the printing industry requirements an ultra-fast curing step of utmost importance to reduce the process time within the printing line. Excimer laser annealing (ELA) can be viewed as a viable solution, offering high quality materials at a reduced process time (in the ns regime). In this work, we evaluate the effect of UV irradiation in single and multilayer dielectrics thin films using SCS at low temperatures. In addition, fully solution-based aluminium oxide (AlOx)/indium oxide (InOx) thin film transistors (TFTs) using printing techniques (flexographic and inkjet printing, respectively) were achieved showing great reproducibility in flexible substrates. In order to decrease process curing time a novel approach was pursued by combining thermal annealing and laser curing. Optimized dielectric layers using just 1 min of thermal annealing followed by ELA treatment were reached being compatible with roll-to-roll (R2R) production methods. In the near future a combination between printing techniques and ultra-fast curing will be crucial for a low-cost manufacturing to achieve high performance and sustainability.

O.2.3
15:00
Authors : Nina Winkler [1,2], Adhi Rachmat Wibowo [1], Wolfgang Kautek [2], Theodoros Dimopoulos [1]
Affiliations : [1] AIT Austrian Institute of Technology, Center for Energy, Photovoltaic Systems, Vienna, Austria [2] University of Vienna, Department of Physical Chemistry, Vienna, Austria

Resume : Transparent conducting oxides (TCOs) are important components in a variety of applications, including flat-panel displays, functional windows, light emitting diodes or photovoltaics. Group-III doped ZnO is an especially attractive material for TCOs, due to its low-cost and ease of fabrication by low-cost deposition methods. Spray pyrolysis is a solution-based deposition technique, in which a precursor solution is sprayed onto a heated substrate. It was shown that highly transparent and conductive In-doped ZnO (IZO) films can be deposited by spray pyrolysis, even at low In dopant concentrations ~ 4 mol%. However, flammable and/or toxic organic solvents are often reported in the literature as necessary to obtain high-quality films. In this work we present highly transparent and conductive IZO films on glass substrates obtained from aqueous solutions with solely non-toxic raw materials. The influence of the solution composition on the structural, optical and electronic film properties was investigated. In order to demonstrate the industrial relevance of the process, a main focus of the study was to obtain fast deposition through the proper choice of the precursor materials and processing parameters. The influence of the solution composition, deposition temperature and solution flow-rate on the film growth rate was therefore investigated. The optimized deposition process resulted in deposition rate surpassing 55 nm/min, yielding IZO electrodes with > 80% transparency and a sheet resistance of ~20 Ω/sq.

O.2.4
15:15
Authors : Lenka Volfová (1); Misha Vorokhta (2); Jiří Bulíř (1); Michal Novotný (1); Martin Vondráček (1) ; Martin Vrňata (3); Ján Lančok (1)
Affiliations : 1) Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czechia 2) Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czechia 2) Department of Physics and Measurements, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czechia

Resume : Copper oxide Cu2O is an important and well known p-type transition metal oxide semiconductor material which has the advantages of direct band gap 2.1 eV at 300 K, a high absorption coefficient in the visible spectral range. This material has already been employed in the fabrication of electronic devices, thanks to its low cost, non-toxicity and fairly good carrier mobility. For example Cu2O has been used in thin photovoltaic devices, resistive switching, transistors, gas sensors or catalysts. In our work the epitaxial Cu2O (110) and Cu2O(001) films has been fabricated by Pulsed Laser Deposition on MgO(100) and SrTiO3(001) substrates respectively. The oxygen pressure in the chamber was varied between 10-3 Pa and 0,1 Pa, while the substrate temperature was between 600 and 750 °C. The crystalline quality and out-of-plane orientation of the films were characterised by means of X-ray diffractometers. The role of the deposition conditions on crystalline structures and morphology. The optical properties, complex dielectric constants, and optical gap, of the films were determined by spectral ellipsometry in the range of 250 - 1700 nm. The surface morphology was characterised by Atomic Force Microscopy. Because we focused on utilization of the Cu2O films as gas sensors, the powerful technique near ambient pressure photoelectron spectroscopy (NAP-XPS) was carried out to investigation of surfaces in the presence of gasses and vapours. The idea was to observe the reaction of the oxygen and hydrogen species on the surface of Cu2O while exposed to atmosphere as a function of temperature as well as in-situ- resistivity measurements.

O.2.5
15:30
Authors : Li Liu, Mariko Ueda, Misaki Nishi, Giang T. Dang, Hiroshi Yanagimoto, Tomoko Kozaki, Toshiyuki Kawaharamura
Affiliations : School of Sys. Eng., Kochi Univ. of Tech.; Res. Inst., Kochi Univ. of Tech.; Res. Inst., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; Material Engineering Div. No.2, Toyota Motor Corporation; Raw Material Development Div. No.2, Toyota Motor Corporation; School of Sys. Eng. & Res. Inst., Kochi Univ. of Tech.

Resume : SnO2:Sb has become one of candidate TCOs with the potential to study base on the Sb is chemically-stable, earth-abundant and non-toxic. With the continuous improvement of fabrication techniques, it has become possible to prepare SnO2:Sb thin films with the resistivity in the order of ~10-4 Ω cm. Usually, obtaining the highly conductive SnO2:Sb required the strict growth conditions, which restrict the SnO2:Sb thin films becoming one of most achievable commercial TCOs. In this work, SnO2:Sb thin films were prepared using some supporting materials, such as inorganic acid, by a laboratory-built mist chemical vapor deposition (mist CVD), which is similar with spray pyrolysis or Aerosol assisted CVD. Owing to the characteristics of 3rd generation mist CVD, which has a fine channel reactor and a supply unit including two solution chambers and one mixing chamber, the precursor and supporting material solutions can be prepared separately to avoid the complex chemical reactions. By corresponding experiments, the SnO2:Sb films with a resistivity of around 5.50 ×10-4 Ω cm (1800 S/cm) were obtained. To study how to improve the electrical properties of thin films, we also investigated the effects of each supporting material and studied the plausible mechanism of fabricating SnO2:Sb films by 3rd generation mist CVD. The details about this 3rd generation mist CVD system and the fabrication of conductive SnO2:Sb thin films using supporting materials will be presented in the conference.

O.2.6
15:45
Authors : Aeran Song, Kwun-Bum Chung , Hojin Lee, Jang-Yeon Kwon
Affiliations : Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea ; Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea ; School of Electronic Engineering, Soongsil University, Seoul 07040, Republic of Korea ; School of Integrated Technology, Yonsei University, Incheon 21983, Republic of Korea

Resume : Recently, Zinc oxynitride (ZnON) thin-film transistors (TFTs) have attracted significant attention in next-generation large size and high resolution display applications, because of their higher field-effect mobility than that of conventional amorphous indium-gallium-zinc oxide TFTs. Previous studies on ZnON have shown that high mobility semiconductor films can be obtained by reactively sputtering Zn metal target, which involves a simple and inexpensive process. Optimizing the associated TFT properties usually consists of controlling the nitrogen to oxygen anion ratio or thermally annealing. However, these previous studies have mainly focused on the field effect mobility on the device characteristics and did not show enhanced bias stability. Therefore, the bias stability on the ZnON TFTs has yet to be fully clarified. For this reason, we investigate the electrical performance and bias stability of the ZnON TFTs and find that silicon (Si) doping during the thin film growth by co-sputtering a SiO2 target with Zn metal target can more effectively improve the bias stability of ZnON TFTs. The bias stabilities of ZnON thin-film transistors were significantly improved using Si doping. About 1% Si doped ZnON TFTs showed a saturation mobility of 19.70 cm2/Vs along with dramatic improvements in the threshold voltage shift for NBS within 1.69 V. The effects of Si doping were interpreted by the experimental correlation between device performance and physical analysis as well as by the theoretical calculation.

O.2.7
16:00 Coffee break    
 
Poster session : Valentin Craciun, Maryline Guilloux-Viry, Zoe Barber, Florencio Sánchez
16:30
Authors : Damian Wojcieszak1, Agata Obstarczyk1, Jarosław Doamradzki1, Danuta Kaczmarek1, Tomasz Kotwica1, Katarzyna Zakrzewska2, Roman Pastuszek1
Affiliations : 1 Wroclaw University of Science and Technology, Faculty of Microsystem Electronics and Photonics, Janiszewskiego 11/17, 50-372 Wroclaw, Poland 2 AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, al. Mickiewicza 30, 30-059 Kraków, Poland

Resume : In the recent years, there has been a distinct increase in interest in thin film materials based on metal oxides. This interest is related to the dynamic development of the electronic and optoelectronic industry, and thus with the growing demand for new materials like fabrication of cheap, low-sized, and reliable gas sensors with reduced power consumption and enhanced performances. Recently, due to the well-known electrical properties of cupric oxide (CuO) and titanium dioxide (TiO2), TiO2/CuO heterostructure have emerged as attractive material for gas sensing applications. TiO2/CuO heterostructure is one of the most promising forms of p-n heterojunctions in which the photoexcited charge pairs (electrons and holes) are spatially separated. Four sets of TiO2/CuO thin film heterostructures with various thickness of TiO2 in the range of 10 nm to 90 nm were prepared using multi-magnetron sputtering method. The surface morphology of the prepared thin films and their elemental composition were investigated using scanning electron microscope equipped with the x-ray probe. Structural properties of the prepared TiO2/CuO nano-heterostructures were determined based on the results of the X-Ray Diffraction. In turn, the type of electrical conductivity was evaluated based on the Seebeck effect measurements. Moreover, based on the current-voltage characteristics, specific resistance of prepared nano-heterostructures was determined.

O.P3.1
16:30
Authors : Hyun Bin Kim, Seong Guk Jeong, Dong In Jeong, Seung Hee Choi, Seok Bin Kwon, Young Hyun Song, Jong Hee Kim, Dae Ho Yoon
Affiliations : 1 School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea 2 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University(SKKU), Suwon 440-746, Republic of Korea 3 Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea

Resume : Recently, heat dissipation materials with good insulation and high thermal conductivity have drawn a lot of attention because heat dissipation materials are important to reduce the thermal degradation of lifetime and reliability of devices. Ceramic materials such as AlN, Al2O3, BN have considered as a thermally conductive material due to their high thermal conductivity and insulating properties. The thermal conductivity of ceramics is affected by packing density, particle size and size distribution, processing method and so on. In this work, we fabricated Al2O3-resin hybrid film which can effectively transfer the heat of the device to the heat sink by inkjet printing. The thermal properties of Al2O3-resin hybrid films were measured by thermal resistance measurement, and the insulation properties were measured by I-V curves. Heat flux is affected by the thermal conductivity and the thickness of the film. The Al2O3-resin hybrid film exhibits improved heat flux because the film is 10 times thinner than the conventional Al2O3 heat-dissipating substrate.

O.P3.2
16:30
Authors : Jiyong Chung, Jeong Hee Lee, Kyeounghak Kim, Jaeyoung Lee, Ki Yoon Kim, Sung Jong Yoo, Jeong Woo Han, Jinsoo Kim, and Taekyung Yu
Affiliations : Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin 17140, Korea

Resume : ABSTRACT: Etching process can be one of the useful methods for the morphology control of nanostructures. Using by precise experiments and theoretical calculations, we report a new ZnO etching process triggered by reaction ZnO with transition metal cations and demonstrate that the etching rate and direction could be controlled by varying the kind of transition metal cations. In addition, the developed etching process was introduced to form thin and uniform ZnO layer, which was utilized for the fabrication of improved propylene-selective ZIF-8 membrane via conversion seeding and secondary growth.

O.P3.3
16:30
Authors : Lai Xuan Bach, Vu Thi Hanh Thu, Nguyen Si Hoai Vu, Nguyen Dang Nam
Affiliations : University of Science and Technology of Hanoi, 18 Hoang Quoc Viet Street, Hanoi, 100000, Vietnam; Faculty of Physics and Engineering Physics, University of Science, VNU-HCM, 227 Nguyen Van Cu Street, District 5, Ho Chi Minh City 700000, Vietnam; Institute of Fundamental and Applied Sciences, Duy Tan University, 10C Tran Nhat Duat Street, District 1, Ho Chi Minh City 700000, Vietnam

Resume : Corrosion (of metals and alloys) always have a significant effect on the economy, they pollute the environment and are also hazardous to human health and life. This is one of the main factors which can lead to premature failure of infrastructure in critical sectors. Despite of the developments in corrosion resistant alloys over the past few decades, carbon steel still constitutes 99% of the material used in the oil and gas, aviation, building industries as well as in chemical plants and also in water treatment systems due to the most cost effective option and and easier processing than other alloys such as stainless steel. However, due to poor corrosion resistance in such aggressive environments, the cost savings can only be realized by adding a corrosion inhibitor to the environment or applying a protective coating to the steel or using alloying element. To prevent the steel corrosion, protective coatings provide the benefits of abrasion resistance, non-stick performance and chemical protection as well as the most widely used corrosion protection coatings in the industry to extreme chemical applications for maximum run life. In this study, the hydrophobic titania coatings has been applied by sol-gel technology for improving the corrosion resistance of carbon steel in simulated seawater solution. The coatings have been successfully characterized by scanning electron microscope, X-ray photoelectron spectroscopy and profilometer. Furthremore, protective performance was also confirmed by electrochemical techniques including potentiodynamic and potentiostatic polarizations as well as electrochemical impedance spectroscopy. The results indicated that the hydrophobic titania coatings on carbon steel substrate exhibited high protective efficiency, that is, increasing corrosion resistance with an increase of the coating layer due to lower corrosion current density and higher coating and charge transfer resistances, improved surface roughness, and corrosion performance.

O.P3.4
16:30
Authors : Sebastian Siol (1), Casey Beall (1,2), Noémie Ott (1), Max Döbeli (3), S. David Tilley (2), Lars P.H. Jeurgens (1), Patrik Schmutz (1), Claudia Cancellieri (1)
Affiliations : (1) Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland (2) University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057 Zurich, Switzerland (3) ETH Zurich, Ion Beam Physics, Otto-Stern-Weg 5, 8093 Zurich, Switzerland

Resume : TiO2 and WO3 are two of the most important earth-abundant materials for electronic and energy applications. Particularly for smart windows, WO3 is one of best performing materials to date [1]. TiO2 and WO3 show similar functional properties, but at the same time vastly different stability in reactive environments. In this study, oxides are grown on solid solution WxTi1-x alloy precursors covering a wide compositional range (0≤x≤1) with the goal of creating functional oxides with tailored stability. The precursors are oxidized using either thermal oxidation or anodizing, corresponding to near-equilibrium and off-equilibrium growth methods, respectively. Combinatorial high-throughput techniques are used to investigate the oxide phase formation, revealing a composition dependent evolution of the oxide crystal structure. In addition, different oxidation conditions result in varying degrees of Ti-surface enrichment as evidenced by XPS-mapping and cross-sectional TEM. Dense and uniform TiO2 surface layers of a few nm thickness can be achieved on top of the oxide alloy for precursors with Ti concentrations >50 at.% resulting in a significantly improved stability in alkaline and acidic environments. At the same time, the optical band gap remains mostly unaltered suggesting that an independent control of functional properties and chemical stability is possible in this system [2]. [1] Adv. Funct. Mater., 2011, 21(12), 2175–2196 [2] ACS Appl. Mater. Interfaces, 2019, in review

O.P3.5
16:30
Authors : Tae Hyeon Kim, Esther Lee, Jee Hoon Kim, Tae Gun Jeong, Jaeun Kim, Byungjin Cho*
Affiliations : Department of Advanced Material Engineering, Chungbuk National University, Chungbuk 28644, Republic of Korea

Resume : Sol-gel processed InGaZnO (IGZO) metal-oxide thin film transistors (TFTs) with high-K dielectrics have attracted considerable attention for next generation display technology due to their high optical transparency, high electrical characteristics, low power consumption, low cost, and large-area processability. However, the issue of electrical instability for metal-oxide TFTs still remains unresolved. Herein, we studied how post-annealing treatment influence the electrical properties and stability of IGZO TFTs with Al2O3 gate dielectric. The post-annealed device showed negligible hysteresis behavior and relatively high mobility compared with the control device without post-annealing treatment. Endurance characteristics was also further improved after post annealing treatment. Depth profile analysis of X-ray photoelectron spectroscopy proved that the post annealing reduced M-OH bonding and induced more M-O bondings at interface between IGZO channel layer and Al electrodes, improving contact property. This simple heat treatment also reduced the number of defect sites between the electrode and the channel layer. The simple post annealing approach is able to provide the strategy toward implementation of stable sol-gel oxide TFT transistor.

O.P3.6
16:30
Authors : Jun-Gyu Choi, Myung-Han Yoon
Affiliations : School of Materials and Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, South Korea

Resume : In this research, we developed a rapid low-temperature crystallization method for reliable crystalline metal oxide semiconductors via excimer lamp-based deep ultraviolet (DUV) photoactivation. Sol-gel indium oxide films were prepared on SiO2/p -Si substrates by spin-coating and photoactivated under nitrogen using excimer lamp (EL, 172 nm, 40 mW/cm2) for 5 min. Resultant thin-film transistors (TFTs) based on photoactivated indium oxide films at 200oC exhibited excellent device performance (μsat ~ 10 cm2V-1s-1) with low statistical distributions. Various physicochemical film analyses and characterizations confirmed that EL provides an efficient route to form crystalline metal oxide films in terms of rapid film crystallization, less defect generation, and batch-to-batch variation in comparison with the DUV photoactivation based on low-pressure mercury lamp (LPML).

O.P3.7
16:30
Authors : Sera Kwon 1, Min Jung Kim 1, Kwun-Bum Chung 1, Hojin Lee 2
Affiliations : 1 Division of physics and semiconductir science, Dongguk University 2 School of electronic engineering, Soongsil University

Resume : Oxide based resistive random access memory (ReRAM) is a good candidate for the next-generation nonvolatile memory due to its simple structure, low cost, outstanding stability, low power consumption, and rapid on/off programming speed. Recently, multi-level cell (MLC) memory has been greatly attracted because MLC memory can store multiple-bits per cell, unlike single-level cell which can only store one-bit per cell. In order to realize the transparent MLC memory in our study, the TiOx ReRAM device was fabricated with embedding the SiO2 nanoparticle on glass substrate, and we obtained four distinct resistance states with stable endurance by controlling the reset voltage. Also, we investigated multi-level switching mechanism according to the analysis of the electronic structures. From analysis on the electronic structures, we found that oxygen vacancy is key role as acting the conductive filament in SiO2 nanoparticle embedded TiOx ReRAM under the positive bias voltage, and the SiO2 nanoparticle acts as the insulating barrier under the negative bias voltage.

O.P3.8
16:30
Authors : Lars Dörner, Patrik Schmutz, Ralf Kägi, Maksym V. Kovalenko, Lars P.H. Jeurgens
Affiliations : Lars Dörner1,2; Patrik Schmutz1; Ralf Kägi3; Maksym V. Kovalenko2,4; Lars P.H. Jeurgens1 1 Empa – Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Joining Technologies & Corrosion, Dübendorf, Switzerland 2 ETH Zürich, Department of Chemistry and Applied Biosciences, Zürich, Switzerland 3 Department Process Engineering, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland 4 Laboratory for thin films and photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland

Resume : CuO nano-particles (NPs) find various applications in e.g. catalysis, energy conversion, magnetic storage, nano-thermites, printable electronics and nano-joining. Agglomerated NPs in dispersion may be transferred onto a substrate surface to yield a porous film with a very high effective surface area. This study shows a cost-effective and straightforward procedure to achieve porous CuO films with very high specific surface area and tunable thickness (from the nanometer up to the micrometer range) onto various substrates by electrophoretic deposition from a tailored CuO NP dispersion. Reproducible thin-film thicknesses and morphologies can only be obtained if the surface charge and mobility of the CuO NPs agglomerates in the dispersion are adapted to the deposition parameters through selection of suitable types and concentrations of solvent and surface agent. Moreover, the size and shape of the employed CuO NPs should be chosen such as to ensure sufficient mobility, while at the same time preventing accelerated agglomeration of dispersed NPs in the solution during the deposition step (resulting in non-uniform film morphologies). The influence of the deposition parameters on the deposition rate and the resulting film morphology were investigated for different combinations and concentrations of solvents and detergents, electrode materials, as well as for different sizes and shapes of employed CuO NPs. First, the size, shape, phase purity and effective surface area of the employed CuO NPs were analyzed by SEM, TEM, BET and XRD. Prior to deposition, the different CuO NP dispersions were characterized by Dynamic Light Scattering (DLS). Finally, the deposition rate, film morphology and effective surface area of the produced CuO films were investigated by SEM, BET and XRD, as function of the NPs size and shape, the dispersion composition and the deposition parameters. As such, porous CuO films with a uniform morphology, tunable thickness and high effective surface area could be achieved in a reproducible manner.

O.P3.9
16:30
Authors : Oana Tatiana Nedelcu1, Mirela Suchea1,2, Titus Sandu1, Ioan Valentin Tudose2,3, Marian Popescu1, Petronela Pascariu4, Catalin Tibeica1
Affiliations : 1 National Institute for Research and Development in Microtechnologies - IMT Bucharest, Romania; 2 Center of Materials Technology and Photonics, School of Electrical Engineering, Technological Educational Institute of Crete, Heraklion, Greece; 3 Chemistry Faculty, University of Crete, Heraklion, Crete, Greece; 4 ”Petru Poni” Institute of Macromolecular Chemistry, Iasi, Romania

Resume : Zinc oxide has a strong potential as transparent conducting oxide for optoelectronics applications that require transparent electronics. Significant efforts are currently made to increase the conductivity of existing materials with no loss of transparency. In this work we investigated the performances of pure and Al-doped ZnO as material for electrodes used in microfluidic systems for bioparticles manipulation by electrokinetic effects. Integration of transparent electrodes in such systems could be exploited to simultaneously electric and optic detection and analysis of bioparticles. While electrokinetics requires specific ranges of intensity and spatial variation of electric field, the conductivity of doped ZnO can have large variation as function of material structuring determined by dopant type and concentration, and the preparation methods. Coupled electric modelling of microfluidic system with ZnO electrodes was performed in order to find the electrodes efficiency in terms of induced field in fluid region as function of electrodes conductivity and fluid properties. Thin films of pure and Al doped ZnO were prepared by spray method on glass substrate, followed by postprocessing annealing and characterized by optical (UV-VIS, SEM) and electrical methods. The results showed that films are transparent in visible range, and that the raised conductivity induced by increasing of Al concentration allows to be used as electrodes materials for low and medium buffer conductivity.

O.P3.10
16:30
Authors : Mariya Khokhlova [a,b], Mira Hammad [b,c], Eva Lhuissier [b], Adrian David [a], Wilfrid Prellier [a], Karim Boumédiene [b,c]
Affiliations : [a] CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Bvd Maréchal Juin, 14050 Caen Cedex, France; [b] BioConnect, Université de Caen Normandie, CHU Niveau 3, 14032 Caen Cedex, France; [c] Fédération Hospitalo Universitaire Surface

Resume : Mesenchymal stem cells (MSCs) are adult multipotent progenitor cells that have a great potential in the field of regenerative medicine and tissue engineering due to their ability of differentiation into several lineages under appropriate conditions [1]. Interestingly, metal oxides thin films have attracted attention in the study of cell behavior thanks to their remarkable physical properties and biocompatibility [2]. However, the number of studies on the interaction of oxide coatings and progenitor cells is limited. Here, we investigated the behavior of MSCs seeded on different oxide thin films (VOx, TiO2, Al2O3) that have been coated on the surface of glass substrates via pulsed laser deposition (PLD) technique. Human mesenchymal stem cells derived from bone marrow were cultured on these substrates and their biological behavior, including adhesion, proliferation and differentiation, was further evaluated. We believe that our study will provide a better understanding of correlation between surface chemistry and MSCs response, which has a high significance in the field of biomaterials fabrication. This work belongs to the INCOX project, funded by Conseil Regional de Basse Normandie. MK is a recipient of a fellowship from French ministry of research. References: 1. Park, J.S., Suryaprakash, S., Lao, Y.-H., Leong, K.W., 2015. Engineering mesenchymal stem cells for regenerative medicine and drug delivery, Methods 84, 3–16. 2. Boudot, C., Kuhn, M., Kuhn-Kauffeldt, M., Schein, J., 2017. Vacuum arc plasma deposition of thin titanium dioxide films on silicone elastomer as a functional coating for medical applications. Materials Science and Engineering C 74, 508–514.

O.P3.11
16:30
Authors : Jeong-Hyun Woo, Na-Hyang Kim, Sun-Young Park, Ju-Young Kim
Affiliations : School of Materials Science and Engineering, UNIST (Ulsan National Institute of Science and Technology), Ulsan 44919, Republic of Korea

Resume : Amorphous structure aluminum oxide (Al2O3) films are used for various applications such as gas- and moisture-diffusion barriers. Al2O3 films deposited by atomic layer deposition (ALD) have good step coverage, high density and low surface roughness. However, these films contain more impurities and need longer processing time at lower growth temperatures. Plasma-enhanced ALD (PEALD) using trimethylaluminum (TMA) and O2 plasma was less dependent on temperature than thermal ALD. In this study, Al2O3 films were deposited by PEALD to protect flexible devices from moisture. By Griffith’s theory, the fracture strength of brittle materials reaches an ideal strength at a critical thickness. So in this study, we fabricated uniform and dense amorphous aluminum oxide film using plasma-enhanced ALD. We look at the critical thickness of amorphous Al2O3 films, which are brittle materials, and the changes in the mechanical behavior of amorphous Al2O3 when thickness is reduced. The push-to-pull in-situ tensile test was used here to measure mechanical properties of ultra-thin films. For sample preparation, Al2O3 films were deposited using ALD and thin-films were fabricated with dog-bone shape using focused ion beam(FIB).

O.P3.13
16:30
Authors : Chiara Maurizio (1), Niccolò T. Michieli (1), Boris Kalinic (1), Anna Marafon (1), Leonardo Girardi (2), Gian-Andrea Rizzi (2), and Giovanni Mattei(1)
Affiliations : (1) Physics and Astronomy Department and CNISM, University of Padova, via Marzolo 8, I-35131 Padova, Italy; (2) Department of Chemical Sciences, University of Padova, via Marzolo 1, I-35131 Padova, Italy.

Resume : Several transition metal oxides (TMO) with nano-scale architecture show exceptional performance during catalysis. [1-3]. Nanostructured TMO thin films allow in addition electrical bias useful for elettrocatalysis and easy catalyst recovery [3]. Despite TMO nanowiskers, nanoneedles, nanopetals have been widely produced by thermal oxidation of a metallic film in the last decade, the mechanism driving their growth out of the sample surface is actually debated. It has been proposed that metal-oxide nano-needles grow from nano-cracks on the surface of metallic particle that form upon oxidation, or that the growth is assisted by a solid-liquid-solid mechanism [4]. We show new results on the formation of Fe2O3 nanowiskers and Co3O4 nanopetals based on X-ray Absorption Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy, suggesting a different mechanism for the nanostructure growth upon thermal oxidation, based on out-diffusion of metal through a thin oxide layer. These results allow a detailed control of the TMO nanostructure formation for a tailored design driven by the specific technological request. [1] X. li, et al., Chem. Soc. Rev. 45 (2016) 2603. [2] R. Edla, et al., Appl. Catal. B 166-167 (2015) 475. [3] L. Girardi, et al. Surface 2 (2019) 41. [4] B. Varghese, et al., Adv. Func. Mater. 17 (2007) 1595.

O.P3.14
16:30
Authors : Na-Hyang Kim, Hangeul Kim, Jeong-Hyun Woo, Sun-Young Park, and Ju-Young Kim
Affiliations : School of Materials Science and Engineering, UNIST(Ulsan National Institute of Science and Technology), Ulsan 44919, Republic of Korea

Resume : Thermally grown silicon dioxide film is an important material in integrated circuits (ICs) as gate oxides, doping barrier, surface passivation, etc. as thermal oxidation grows high quality silicon dioxide film showing excellent electrical insulator resistivity, passivation ability to prevent diffusion of dopants, etc. As it has limitations of the substrate, Si, applications for thermally grown silicon is limited. In this research, we studied thermally grown SiO2 film as an encapsulation film by using its ultra-low water permeability as we expected thermally grown silicon dioxide film to have ultra-low water permeability and high elasticity due to its rare defects, high density and high uniformity. And we increased stretchability of thermally grown silicon dioxide film with two ways, using thickness effect and applying wrinkled structure. To increase the stretchability, first, the thickness of thermally grown SiO2 films were decreased less than 200 nm to observe thickness effect. Tensile tests were performed on those films and the results showed that thinner film has higher elastic limit than thicker film has. Second, wrinkled structures were applied on thermally grown SiO2 film by using prestrained elastomer and the wrinkled SiO2 film having 5% of stretchability was fabricated. The influence of thickness on mechanical properties of thermally grown SiO2 film and mechanical behavior of wrinkled SiO2 film during the fabrication and while stretching will be discussed.

O.P3.15
16:30
Authors : B. El Filali1, J.A. Jaramillo Gomez1, T.V. Torchynska2, J.L. Casas Espinola2 and L. Shcherbyna3
Affiliations : 1Instituto Politécnico Nacional, UPIITA, México City, 07320, México 2Instituto Politécnico Nacional, ESFM, México City, 07738, México 3V. Lashkaryov Institute of Semiconductor Physics at NASU, Kyiv 03028, Ukraine

Resume : In-doped ZnO films grown by ultrasonic spray pyrolysis method have been studied by means of the scanning electron microscopy (SEM), energy dispersive X ray spectroscopy (EDS) and X ray diffraction (XRD) methods. The photoluminescence (PL), transmittance and absorbance have been controlled as well. It was shown that the ZnO optical band gap demonstrates the blue high energy shift to 3.31eV at 300K and the PL intensity of near band edge (NBE) emission enlarges at In doping 0.5-2.5at%. Simultaneously, the positions of XRD peaks and their intensities vary insignificantly owing to the difference in the In3+and Zn2+ ionic radii. Meanwhile, intensity decreasing the green PL band confirms the occupation of the zinc vacancies by In ions with the formation of substitutional InZn donor-like defects and ZnO crystal quality improving. At higher In contents the new PL band (3.034eV) appears in PL spectra and its peak shifts to lower energy with In content increasing. This PL band was attributed to the emission via the complex defects, formed by Ini interstitial atoms. Simultaneously, the PL intensity and ZnO film crystallinity falling down, the ZnO crystal lattice parameters increase and the ZnO optical band gap demonstrates the red low energy shift. To reveal a nature of the optical transition responsible for the new PL band, PL spectra have been studied in the temperature range 11-290K. The dependence of the Ini complex defect formation versus In contents in ZnO NC films is analyzed and discussed. The optimal In concentration range to fabricate the ZnO films with high optical parameters has been estimated.

O.P3.16
16:30
Authors : Chetan C. Singh, Emila Panda
Affiliations : Department of Materials Science and Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India

Resume : In order to know the threshold quantity of the zinc interstitials that contributes in an increase in carrier concentration ( ) in the Al-doped ZnO (AZO) films and their effect on the overall microstructure and optoelectronic properties of these films, in this work, Zn-rich- AZO films are fabricated by adding excess zinc (from a zinc metallic target) during their deposition in RF magnetron sputtering and are then investigated using a wide range of experimental techniques. To understand fundamentally the role of zinc atoms in creating the electronic defect states and thereby tuning the overall microstructure and optoelectronic properties of these films, we conducted similar sets of experiments also with the ZnO films. The excessively introduced zinc in these AZO and/or ZnO films is found to increase the shallow donor level defects (i.e., zinc interstitials and oxygen-related electronic defect states), which is found to significantly increase the carrier concentration in these films. Additionally, aluminum is seen to enhance the creation of these electronic defect states in these films, thereby contributing more to the overall carrier concentration of these films. However, carrier mobility is found to decrease when carrier concentration values are higher than 4 ×1020 cm−3, because of the electron-electron scattering. Whereas, optical band gap for the ZnO films is found to increase with increasing because of the B-M shift, these decrease for the AZO films due to the band gap narrowing effect caused by excess carrier concentration.

O.P3.17
16:30
Authors : Hangeul Kim, Na-Hyang Kim, Jeong-Hyun Woo and Ju-Young Kim
Affiliations : School of Materials Science and Engineering, UNIST(Ulsan National Institute of Science and Technology), Ulsan 44919, Republic of Korea

Resume : Organic components in organic electronic device are vulnerable to external environment such as high temperature and humidity. To ensure chemical stability and long-term operation, organic electronic devices require encapsulation layer with low water vapor transmittance rate. Encapsulation of commercialized OLEDs are rigid glass and epoxy resin, which are not suitable for flexible devices requiring high flexibility. TFE (thin-film encapsulation) technique has been studied for flexible device encapsulation. Amorphous materials are selected for TFE materials because they are dense and transparent and do not have fast diffusion paths like grain boundary. Thermally-grown silicon dioxide, oxidized from single crystal silicon substrate at high temperature, has ultra-low water vapor transmittance rate due to high density without pinholes and defects. However, the thermally-grown silicon dioxide thin films have a low elastic limit (<1%) and show brittle fracture alike typical amorphous materials. For that reasons, it is necessary to improve the mechanical properties of the thermally-grown silicon dioxide thin film for TFE. In this study, we tried to improve the stretchability by applying the wavy structure to thermally-grown silicon dioxide and developed the wavy structure texturing of single crystal silicon substrate by using photo-lithography and various etching process. we fabricated a highly-stretchable wavy thermally-grown silicon dioxide TFE by oxidizing wavy textured crystalline silicon substrate. Also, we carried out tensile test and finite element analysis on the wavy and flat thermally-grown silicon dioxide TFE to analyze the stretchability. And then, we discussed about the correlation between the improvement of stretchability and wavy structure.

O.P3.18
16:30
Authors : O. Shavdina (1), C. Grillot (2), A. Stolz (1), F. Delorme (3), V. Bertagna (2), N. Jimmy (2), F. Giovannelli (3), C. Vautrin-Ul (2), N. Semmar (1), C. Leborgne (1).
Affiliations : 1.Université d’Orléans/CNRS 7344, Groupe de Recherches sur l'Energétique des Milieux Ionisés 2.Université d'Orléans/CNRS UMR 7374, Interfaces, Confinement, Matériaux et Nanostructures 3.Université de Tours/ CNRS 7347, Groupe de Recherche en Matériaux, Microélectronique, Acoustique et Nanotechnologies

Resume : Our studies were focused on the inkjet-printing of aluminum-doped zinc oxide (AZO) nanostructures. This additive fabrication technique is based on the printing of an active material by tiny MEMS-jets onto rigid and flexible substrates for the preparation of functional material thin films. In our case, AZO platelets and isotropic spherical AZO nanoparticles were synthesized by aqueous coprecipitation at the GREMAN laboratory (P. Diaz-Chao, F. Giovannelli et al. Journal of the European Ceramic Society, Vol. 34, pages 4247-4256 (2014)). Then, the preparation of the solvent-based ink was performed at the ICMN laboratory with the control of the viscosity, ink stability and nanoparticles dispersion. We also analyzed the influence of the particle shape on the optical (by an ellipsometer), electrical (by the 4 point probe method, electrical impedance), morphological ( by the SEM analysis) and structural properties (by the DRX analysis) of the thin films. These structures turn out to be very promising candidates for sensor applications due to their good transparency, conductivity and non-toxicity.

O.P3.19
16:30
Authors : P. Dubček1, K. Tomić1, B. Šantić1, S. Fazinić1, R. Heller2, S. Akhmadaliev2, H. Lebius3, A. Benyagoub3, F. Scholz4, O. Rettig4, L. Bröckers5, M. Schleberger5, M. Karlušić1*
Affiliations : 1RuđerBošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia 2 Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrase 400, 01328 Dresden, Germany 3 CIMAP, CEA-CNRS-ENSICAEN-UCN, BP 5133, 14070 Caen Cedex 5, France 4Institut für Optoelektronik, Universität Ulm, Albert-Einstein-Allee 45, 89081 Ulm, Germany 5 Fakultätfür Physik and Cenide, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany

Resume : In radiation hard materials there is a rather high threshold in incoming ion energy below which ion track formation does not occur. However, this threshold can be significantly reduced by low energy pre-irradiation. As an example, previous studies on GaN found the threshold to be at about 20 keV/nm electronic stopping power for ion incidence close to normal to surface. It has been lowered down to 8 keV/nm after pre-irradiation by 2MeV Au ions. This has been confirmed by RBS/c and AFM measurements where change in surface roughness has been found. Grazing incidence swift heavy ion irradiation effectively increases volume density of the absorbed energy leading to higher concentration of the formed defects. In combination with the vicinity of the surface, it also results in lowering of the surface ion track formation threshold. These surface tracks have been studied in MgO, Al2O3 and MgAl2O4. Earlier results proved these materials to be radiation hard, and the threshold for the track formation is found to be in 10-15 keV/nm range for nearly normal irradiation. Switching to grazing incidence reduces the threshold down to 8 keV/nm. Here, the tracks are clearly visible on surface by AFM.

O.P3.20
16:30
Authors : Lina Sun, Yu Kurosawa, Tsukasa Yoshida, Yoshiyuki Suzuri
Affiliations : Yamagata University, Japan

Resume : Metal oxides such as TiO2, ZnO, SnO2 and zinc tin oxide (ZTO) are useful in many of energy devices because of their high chemical stability, n-type semiconductivity and photoelectrochemical properties. Various methods of solution processing of their thin films are known, such as chemical bath deposition, electrodeposition and sol-gel reactions. Typically, high temperatures need to be applied for crystallization to achieve good properties. The need of high temperature however limits the choice of substrates to heat-resistant materials. Also, crystallization often results in pinholes and cracks to damage the performance of devices. We have developed an alternative sol-gel method to obtain ultra-smooth thin films of various metal oxides at room temperature, by employing photochemical decomposition of coated precursor by vacuum ultraviolet (VUV) light (λ= 172 nm, Eph = 7.2 eV). The method is compatible with conductive plastic film substrates, so that multiple applications in thin film devices such as transparent conductive layer, light emitter, buffer layer in solar cells and thin-film encapsulation (TFE) for organic electronic devices can be envisioned.

O.P3.21
16:30
Authors : Dieter Schmeißer1*, Klaus Müller1, Karsten Henkel1, and Christoph Janowitz2
Affiliations : 1Angewandte Physik-Sensorik, BTU Cottbus-Senftenberg, K.-Wachsmann-Allee 17, 03046 Cottbus, Germany 2Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, German

Resume : We report on the electronic structure of gallium oxide (Ga2O3) single crystals as studied by resonant photoelec-tron spectroscopy. We determine the ionicity factor and describe the electronic structure by mixed-atomic va-lence states which enable the formation of intrinsic defects. The electronic structure of Ga2O3 is determined with these intrinsic defects and we explain in that context the mechanisms to create intrinsic, thermally activated, and dipole assisted charge carriers. We discuss in this context the optical data and the doping induced changes. Finally, we focus on the mechanisms to enhance the p-type conductivity in Ga2O3 and in related amorphous thin films. The electronic structure of Ga2O3 can be understood as a model system for the family of the transparent con-ducting oxides as we have observed the intrinsic defect states in several investigated materials systems (ZnO, In2O3, SnO2, IGZO) indicating similar mechanisms for the defect formation, the optical excitations, and the transport properties.

O.P3.23
16:30
Authors : P. Prepelita 1, D. Craciun 1, I. Stavarache 2, F. Garoi 1, M. Dumitru 1, C. Negrila 2, B. Sbarcea 3, V. Craciun 1
Affiliations : 1 National Institute for Laser, Plasma and Radiation Physics, PO Box MG-36, Magurele 077125, Ilfov, Romania 2 National Institute of Materials Physics, 105 bis Atomistilor Street, PO Box MG-7, Magurele 077125, Ilfov, Romania 3 ICPE-CA, Splaiul Unirii 313, Sector 3, 74204, Bucharest, Romania

Resume : It is shown that the rapid thermal annealing (RTA) process in a conventional environment can result in improvements of the quality of indium tin oxide (ITO) films used as conductive transparent electrode for photovoltaic structures. The ITO thin films were deposited at room temperature by radio frequency magnetron sputtering (rf-MS) technique onto quartz substrates. X-ray diffraction investigations showed a tetragonal nanocrystalline structure for these thin films. After deposition, the ITO films were subjected to the RTA process at 525 °C (heating rate 20 °C/s), maintained on a thermal plateau for 10 minutes, then cooled down to room temperature with a rate of 20 °C/s. Following this process, both structural qualities and optical band gap values improved considerably, while polycrystalline ITO compounds with a textured (222) plane and a preferential orientation along the c axis were obtained. X-ray photon spectroscopy (XPS) highlighted the increase in thin film quality and the beneficial effect on the chemical composition after rapid heating. Using Tauc’s plot, it was determined that values of the optical band gap ranges between 3.44 and 3.72 eV. These values vary depending on the heat treatment and the thickness of the analyzed sample. Optical constants (refractive index n, extinction coefficient k, and absorption coefficient α) of the ITO films were determined using Swanepoel’s method. Highly conductive indium tin oxide thin films (ρ = 5 × 10-3 Ω cm) were obtained by RTA in an open atmosphere. Following rapid thermal treatment, the ITO thin films showed improved optical transparency and electrical conductivity. Such films could be used to manufacture transparent contact electrodes for solar cells.

O.P3.24
16:30
Authors : Hyunmin Hong1, Kwun-Bum Chung1, Choi Dukhyun 2
Affiliations : 1. Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea 2. Division of Nanostructures and Nanomaterials, Kyunghee University, Yongin 17104, Republic of Korea

Resume : Transparent amorphous oxide semiconductors (AOSs) have been paid wide attention as an attractive active channel layer with high switching speed, for various electronic display applications, including liquid crystal displays (LCDs) and active-matrix organic light emitting diodes (AMOLEDs). Compared with conventional amorphous/poly-silicon thin film transistors (TFTs), oxide TFTs have significant advantages, such as high electron mobility, transparency, low temperature, and low-cost process, with the preservation of the amorphous structure. Various semiconductors based on indium and zinc oxide compounds have been intensively studied, since the 2004 report on amorphous indium-gallium-zinc oxide TFTs with high device performance. However, for practical mass production, higher device performance and better device instability still remain as some of the most important and critical issues. Recently, many efforts have been made to seek alternative oxide semiconductors with good stability under bias and illumination stress, using combinatorial material design. In this presentation, physical analysis of Indium based oxide semiconductor films with multi-cations will be discussed in terms of electronic structure related to defect states below the conduction band by photo-induced current transient spectroscopy(PICTS). These interpretation could be helpful to figure out the electrical properties of films and to predict the performance and reliability of oxide TFTs.

O.P3.25
16:30
Authors : Nam-Kwang Cho, Hyun-Jae Na, Youn Sang Kim
Affiliations : Nam-Kwang Cho 1. Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea; Hyun-Jae Na 1. Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea; Youn Sang Kim 1. Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea 2. Advanced Institute of Convergence Technology, Suwon 443-270, Republic of Korea

Resume : Transferring charge carriers through an insulator film between two metal electrodes is a major issue in various electronic devices, including metal/insulator/metal (MIM) diodes and resistive switching memories. Recently, a new concept has been suggested that can uni-directionally control the direction and magnitude of the vertical current in a metal/insulator/oxide semiconductor/metal (MIOsM) structure by utilizing a bulk-limited conduction mechanism that depends on the trap and sub-gap states in the insulator. This shows the potential to expand the processing window of conventional electronic devices which follows electrode-limited conduction mechanism. However, it is still insufficient to provide direct evidence that the flow of electrical current in the MIOsM structure is due to bulk-limited conduction within the insulator. In this study, we fabricate P Si/AlOx/Al (MIM) and P Si/AlOx/IGZO/Al (MIOsM) thin film diodes using a solution-processed aluminum oxide as an insulator layer which has relatively rich sub-gap states. After fabrication of the AlOx thin film, atmospheric-pressure plasma treatment was performed with different time on the AlOx thin film for effectively control the defect state. Through XPS analysis of AlOx, we confirmed that the correlation between defect states controlled by the atmospheric plasma treatment time of the insulator directly affects the I-V curves of the MIM and MIOsM diodes. This results would provide a clue for employing approach of current flow through insulating film to applications such as rectifiers, switching devices, amplifiers and oxide thin film diodes.

O.P3.26
16:30
Authors : Alina Matei (1), Vasilica Ţucureanu (1,2), Marian Cãtãlin Popescu (1), Cosmin Romanițan (1,3), Bianca Cãtãlina Ţîncu (1,4), Marioara Avram (1)
Affiliations : (1) National Institute for Research and Development in Microtehnologies IMT-Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Bucharest, Romania (2) Transilvania University of Brasov, Department of Materials Science, 29 Eroilor Blvd, 500036 Brasov, Romania (3) Faculty of Physics, University of Bucharest, 405 Atomistilor Street, 077125 Magurele, Romania (4) University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 0110

Resume : The researches achieved of last time have been focused on the development of a chemical synthesis method for preparing silver oxide nanoparticles due to their practical applications, such as coatings for medical devices, antimicrobial agents, optical biosensor, cosmetic and therapeutic products. This paper presents the synthesis and characterization of silver oxide powder obtained by a wet chemical method, using inorganic silver salt (AgNO3), sodium hydroxide (NaOH) in the presence of polyethylene glycol (PEG) as a surfactant agent. The process parameters were monitored by the effect of several processing variable (concentration, reaction pH, time and temperature, etc.) which influenced the particle size and morphology of silver oxide nanoparticles. The synthesized silver oxide nanoparticles were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX). The FTIR spectrum of silver oxide particles indicate a band below 600 cm-1 corresponding to the stretching vibration of Ag-O band. The XRD analysis reveals that the average crystallite size of the Ag2O particles was found to be about 20 nm. SEM analysis disclosed the morphology as a spherical shape of silver oxide particles with the particle size within the range of 10-35 nm. The analysis of the synthesized powder using EDX showed the presence of the Ag and O atoms indicating the formation of silver oxide.

O.P3.27
16:30
Authors : Jiri Bulir, Ladislav Fekete, Jan Drahokoupil, Martin Vondracek, Michal Novotny, Premysl Fitl, Jan Lancok
Affiliations : Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8; Department of Physics and Measurements, University of Chemistry and Technology Prague

Resume : SnO2 has been widely used in gas sensors as sensing layer for detection of reducing gases like CO, H2, CH4. Its functionality is based on changing of electrical resistance/impedance of the semiconducting active layer in the presence of reducing gas. The reducing gas reacts with oxygen adsorbates at the surface and releases an electron in conduction band increasing the electric conductance of the sensing SnO2 layer. Thus the adsorption of reducing gas species control the conductivity of layer that strongly depends on surface morphology and structure of SnO2. In this work, we focus on the preparation of nanostructured SnO2 coatings in order to increase the surface of the sensing medium. The SnO2 coatings were prepared by means of DC magnetron sputtering from Sn metallic target in Ar/O2 gas mixture. The preferential columnar growth was boosted by substrate tilting. The “zig-zag” columnar structure was created by alternating the tilt angle during the deposition process. The spiral-like columnar structure was obtained by rotation of the sample around the axis normal to the substrate surface that is tilted by a fixed angle with respect to the direction of arriving ions. The low gas pressure of about 0.5 Pa was chosen in order to enhance directionality of the arriving species. The columnar structure of the prepared coatings was studied by means of scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The composition and bonding were analyzed by x-ray photoemission spectroscopy. The crystallinity and surface morphology were analyzed by x-ray diffraction (XRD) and atomic force microscopy (AFM). The electron-transport properties were evaluated by Van der Pauw method and Hall effect measurement.

O.P3.28
16:30
Authors : Hyunmin Hong1, Kwun-Bum Chung1, Choi Dukhyun 2
Affiliations : 1. Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea 2. Division of Nanostructures & Nanomaterials, Kyunghee University, Yongin 17104, Republic of Korea

Resume : Transparent amorphous oxide semiconductors (AOSs) have been paid wide attention as an attractive active channel layer with high switching speed, for various electronic display applications, including liquid crystal displays (LCDs) and active-matrix organic light emitting diodes (AMOLEDs). Compared with conventional amorphous/poly-silicon thin film transistors (TFTs), oxide TFTs have significant advantages, such as high electron mobility, transparency, low temperature, and low-cost process, with the preservation of the amorphous structure. Various semiconductors based on indium and zinc oxide compounds have been intensively studied, since the 2004 report on amorphous indium-gallium-zinc oxide TFTs with high device performance. However, for practical mass production, higher device performance and better device instability still remain as some of the most important and critical issues. Recently, many efforts have been made to seek alternative oxide semiconductors with good stability under bias and illumination stress, using combinatorial material design. In this presentation, physical analysis of Indium based oxide semiconductor films with multi-cations will be discussed in terms of electronic structure related to defect states below the conduction band by photo-induced current transient spectroscopy(PICTS). These interpretation could be helpful to figure out the electrical properties of films and to predict the performance and reliability of oxide TFTs.

O.P3.29
16:30
Authors : Elif PEKSU, Hakan KARAAGAC
Affiliations : Istanbul Technical University, Department of Physics

Resume : In this investigation, hydrothermal technique was employed for the synthesis of dense arrays of ZnO nanowires (NWs) due to its many advantages such as providing a contamination free growth route and allowing large-scale production of ZnO NW arrays in a cost effective manner on a wide range of substrates including silicon, soda lime glass (SLG), transparent conductive oxides (TCO) (e.g, ITO and FTO). Choosing the appropriate substrate is a critical issue due to the fact that the lattice matching between the deposited film and the substrate will determine the quality of the deposited material. Results showed that ZnO NWs can be successfully grown on any substrate that can withstand a temperature of 90 oC and the constituent precursors used for the preparation of the growth solution, such as zinc acetate dehydrate in 2-proponal and ethanolamine. The effect of both ZnO seed layer, required for the synthesis of ZnO nanowires, and growth parameters on quality of NWs was investigated in details. ZnO seed layers were deposited by cost-effective sol-gel technique. Results demonstrated that there was a strong correlation between some growth parameters (e.g., ZnO seed layer deposition route and thickness, reaction temperature and growth time) and the quality of the fabricated ZnO NWs in terms of their orientation, uniformity, density and diameter. It was also found that there was a significant effect of growth time on the diameter of the grown ZnO NWs, ascribed to the fusion of poorly aligned NWs at longer growth periods. Following the optimization of ZnO NWs, they were employed for the construction of TCO/ZnO/ZnO NWs/CdS/CZTS core-shell structured solar cell. As an absorber layer (shell) of this architecture, a kesterite compound (Cu2ZnSnS4 (CZTS)) was preferred, which is regarded as an alternative material to the most commonly employed material (CuInSe2) in thin film based solar cells. In order to form CZTS thin films, solution based sol-gel technique was preferred. Before their incorporation into the core-shell device structure as the shell component, they were deposited on glass substrates for determining their structural, electrical and optical properties in detail. Once the optimum parameters (single phase, band gap and annealing temperature) for an effective absorber layer was determined, ZnO NWs 1.2-1.3 µm in length and 65-95 nm in diameter were decorated with a ~ 600 nm thick CZTS thin film for the fabrication of the aforementioned solar cell architecture. Thermally-evaporated In and pre-coated ITO were employed as bottom and top contacts of the device, respectively. After ensuring the formation of p-n heterojunction, the performance of the fabricated prototype solar cell was then tested under standard light illumination (100 mW/cm2).

O.P3.30
16:30
Authors : Y. Vygranenko (1), M. Fernandes (1&2), M. Vieira (1&2), G. Lavareda (1&3), C. Nunes de Carvalho (3&4), P. Brogueira (4&5), A. Amaral (4&5)
Affiliations : 1) CTS-UNINOVA, Campus da Caparica, 2829-516 Caparica, Portugal 2) Departamento de Engenharia Electrónica e Telecomunicações e de Computadores, ISEL, Lisbon, 1950-062, Portugal 3) Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica 4) CeFEMA, Instituto Superior Técnico, Av. RoviscoPais 1, 1049-001 Lisboa, Portugal 5) Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal

Resume : Commercial polymer films with indium-tin oxide (ITO) coatings are considered to be the most promising transparent electrode component for flexible electronics. Substrate materials such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) are most attractive due to their high transparency and low cost. However, the properties of low-temperature ITO on these plastics are substantially inferior in comparison to ITO grown on glass substrates at high temperatures. In this contribution, we report on low temperature deposition of conducting indium oxide films by a radio-frequency plasma enhanced reactive thermal evaporation (rf-PERTE) technique. The films were deposited on PET without intentional heating of the substrate and at elevated temperatures up to 150 oC. The material stoichiometry was accurately controlled by adjusting deposition conditions including the oxygen flow, process pressure, pumping speed, and RF-power. Besides, fine turning of the critical deposition parameters during the deposition was implemented by measuring the variation of film conductance in-situ. The film morphology and surface roughness were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The Hall effect measurements were also performed to determine the relation between the deposition conditions and the electrical properties of the films. The resistivity of 0.4 mΩ-cm was reached under optimized deposition conditions. A 250-nm-thick coating with 16 Ω/sq sheet resistance shows an 82% peak value of transmittance in the visible spectral range.

O.P3.31
16:30
Authors : 1 Eva Horynova, 1 Brianna Conrad, 1 Amalraj Peter Amalathas, 1 2 Lucie Abelova, 3 Ognen Pop-georgievski, 2 Zdenek Remes, 1 2 Jakub Holovsky
Affiliations : 1 CTU Faculty of Electrical Engineering, Technicka 2, 166 27 Prague, Czech Republic; 2 Institute of Physics CAS, Cukrovarnicka 10/112, 162 00 Prague, Czech Republic; 3 Institute of Macromolecular Chemistry CAS, Heyrovskeho nam. 2, 162 06 Prague, Czech Republic;

Resume : Transparent conductive oxides are materials which combine properties of electrical conductivity and optical transparency. Therefore, they are widely used in many applications such as solar cells, flat panel displays etc. Nowadays there are a lot of n-type TCOs such as ITO, FTO or AZO but the development of p-doped TCOs could be quite challenging. Some of the most promising materials could be high work function oxides that can serve as hole selective contacts, such as tungsten oxide, molybdenum oxide and vanadium. Thin films of these oxides were prepared by pulsed laser deposition and their optical properties were determined. Samples of well known ZnOx were also prepared for comparison. The effect of different conditions including oxygen level and substrate temperature during the deposition were evaluated. Optical characterization was performed with spectral ellipsometry combined with photothermal deflection spectroscopy, which is a non-contact and non-destructive method for measuring spectra of low absorptance. Absorptance in the bandgap is an indication of the presence of defects such as metallic particles. From the gradient of absorption edge Urbach energy could be obtained, providing an indication of disorder in the material. The work function of each material was obtained by Kelvin probe.

O.P3.32
16:30
Authors : L. G. Carpen, T. Acsente, B. I Bita, V. Marascu, V. Satulu, G. Dinescu
Affiliations : L. G. Carpen - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania,University of Bucharest, Faculty of Physics, Atomiştilor 405 str, Magurele, Bucharest, Romania T. Acsente - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania B. I Bita - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania,University of Bucharest, Faculty of Physics, Atomiştilor 405 str, Magurele, Bucharest, Romania V. Marascu - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania,University of Bucharest, Faculty of Physics, Atomiştilor 405 str, Magurele, Bucharest, Romania V. Satulu - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania G. Dinescu - INFLPR, Atomistilor 409 str, Bucharest- Magurele, Romania,University of Bucharest, Faculty of Physics, Atomiştilor 405 str, Magurele, Bucharest, Romania

Resume : Reduction of tungsten oxides in hydrogen plasma is a green route for production of metallic W, but also for cleaning of surfaces in fusion technology and for nanoscale semiconductor devices patterning processes. In this work, the modification of W surfaces in a two-step process, respectively thermal oxidation followed by reduction in H2 plasma was investigated. Both processing steps were performed using a linear tubular furnace allowing the heating of the samples simultaneous with plasma ignition. The oxidation of the samples was performed in air at a temperature of 800 C. Further on, two types of reduction processes in H2 plasma were performed: at room temperature and by heating the sample at 800 C. Each sample was characterized using profilometry (for roughness), scanning electron microscopy SEM (for morphology) and X-ray photoelectron spectroscopy XPS (for chemical state). After oxidation, the roughness increases from about 100 nm up to 2000 nm and remains in this range after both plasma reduction processes. XPS results showed that only at higher temperature the oxide is totally reduced to metallic W. We highlight that this type of two-step approach increases the surfaces roughness while conserve the surface chemistry, which may be useful for some applications. In addition, the described process may be easily extended to other materials. Acknowledgements We acknowledge the financial support in the frame of the projects: EUROfusion Consortium WPEDU-RO and IFA-CEA C5-07

O.P3.33
16:30
Authors : G. El Hallani 1, M. Khuili 1, N. Fazouan 2,1,*, A. Liba 1, O. Mounkachi 3, A. Mzerd 4, L. Laanab 5, E. H. Atmani 2
Affiliations : (1) Physical Materials Laboratory. Faculty of Sciences and Technologies, Beni Mellal, Morocco (2) Physics of Condensed Matters and Renewables Energies Laboratory. Faculty of Sciences and Technologies, Mohammedia, Morocco (3) Condensed Matter and Interdisciplinary Sciences Laboratory , Faculty of Sciences ,Rabat, Morocco (4) Physical Materials Laboratory. Faculty of Sciences, Rabat, Morocco (5) Conception Systems Laboratory, Faculty of Sciences, Rabat, Morocco (*) Corresponding author fazouan@yahoo.fr

Resume : Transparent Conductive Oxides (TCO) in solar cells are used as transparent electrodes. They must necessarily have a high optical transmission in order to allow efficient transport of photons to the active layer and also good electrical conductivity, which is required to obtain the least losses of transport of photo-generated charges. In this contribution, Al, Mg and Sn doped ZnO thin films (AZO, MZO, TZO) as TCO materials, were synthesized by spin coating method. The structural, optical and electrical properties of these films are investigated as a function of dopant concentration. X-ray diffraction patterns show that all films exhibit the hexagonal würtzite structure with a preferential orientation along [002] direction. The surface morphologies show that AZO and MZO films are homogeneous and dense while TZO films showed different surface morphologies going from homogeneous to porous structure depending on Sn concentration. An enhancement of optical transmittance of about 95% with a blue shift of the gap energy was found for both Al and Mg doped ZnO layers against 70% of average level transmittance and a red shift of optical window for Sn doped ZnO films. Photoluminescence measurements at room temperature, show excitonic peaks corresponding to the AZO, MZO and TZO films with a low defects level for 1% Al doped ZnO compared to MZO and TZO films that showing a large band defects centered around 514 nm. Electrical measurements show that all the films present an Ohmic comportment with a best electrical conductivity of 2.45 S.cm-1 obtained for 1% AZO in accordance with the photoluminescence analysis. The reduced electrical conductivity shown in our films is attributed to a low mobility of charge carriers due to their diffusion by the grain boundaries.

O.P3.34
16:30
Authors : Toshiyuki Kawaharamura, Misaki Nishi, Li Liu, Masahito Sakamoto, Phimolphan Rutthongjan, Shota Sato, Mariko Ueda, Tatsuya Yasuoka, Yuki Tagashira, Tamako Ozaki, Giang T. Dang
Affiliations : School of Sys. Eng., & Res. Inst., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.;

Resume : In our lab, mist CVD has been developed, which is a thin film fabrication method using liquid droplets such as spray pyrolysis and aerosol assisted CVD. Recently, in mist CVD, films of highly-controlled properties has been obtained by precise control of the flow, which is made possible by focused on the fact that the mist is gas-liquid multiphase flow. And, mist CVD has been one of the promising thin film fabrication methods made clear distinction from the other methods using liquid droplets. On the other hand, it was not clear how the precursor contained in the supplied droplets contributed to the film growth, in mist CVD; (1) the reaction proceeds under the liquid phase after the droplets adhere directly to the substrate before evaporation, (2) the reaction proceeds under the gaseous phase after the droplets completely evaporate before the adhering, or (3) the reaction proceeds under both phase with the droplets of Leidenfrost state. In the past, it has found that the reaction process in the Hyp.(1) does not occur when the setting temperature of reactor is higher than the boiling temperature of solvent in mist CVD using a special fine channel type reactor. In this study, ZnO thin film was prepared while the precursor concentration in the reactor was controlled with separately supplying a precursor solution and only a solvent dissolving the precursor. As a result, it was found that the reaction process in mist CVD cannot be explained under the reaction process in the Hyp.(2) because the material diffusion rate calculated from the deposition rate is, at least, one-order or more smaller than the general molecule diffusion rate. In the presentation, we would like to explain and discuss the details of theory and experimental results in detail.

O.P3.35
16:30
Authors : Marlene Härtel, Ruslan Muydinov, Steve Albrecht, Bernd Szyszka
Affiliations : Technische Universität Technologie für Dünnschicht-Bauelemente, Berlin, Deutschland; Helmholtz-Zentrum Institut für Silizium Photovoltaik, Berlin, Deutschland

Resume : Sputtered high-quality transparent conductive oxides (TCOs), with their high conductivity and high transparency in the visible and near infrared wavelengths, satisfy the demanding requirements for the application as top electrodes in tandem solar cells. However, challenges arise when depositing TCOs on top of sensitive Perovskite films due to harsh conditions during the sputter deposition process, such as ion bombardment, and interactions with various plasma constituents including electrons, and ultraviolet or vacuum ultraviolet photons. By deploying a buffer layer with varying thicknesses as well as varying sputter process conditions, such as the reduction of power or sample to target position, the electrical solar cell properties were improved. The origin and influence of sputter-damage on Perovskite films and its charge selective layers are identified by demonstrating the degrading effect of plasma radiation and ion bombardment. Detection and quantification were done by employing appropriate structural, optical and electrical characterization methods. Furthermore, a comparison of two different sputter deposition techniques, namely radio-frequency magnetron sputtering and hollow cathode gas flow sputtering, are shown. The results of this work can serve as fundament for future enhancements in device performance.”

O.P3.36
16:30
Authors : N. Korsunska1, L. Borkovska1, L. Khomenkova1, O. Kolomys1, V. Strelchuk1, T. Sabov1, O. Oberemok1, X. Portier2
Affiliations : 1V.Lashkaryov ISP of NAS of Ukraine, 45 Pr. Nauky, 03650, Kyiv, Ukraine; 2CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 6 Blvd. Maréchal Juin, 14050 Caen, France

Resume : Inorganic phosphor materials based on rare earth (RE)-doped oxides are receiving great attention for potential applications in solid state lighting and display technology. In this work, the effect of thermal annealing on impurity distribution and luminescence of Tb and Eu codoped ZnO films deposited by magnetron sputtering on Si substrate has been investigated. It is shown that incorporation of Tb and Eu ions in ZnO host occurs under deposition. The annealing at 900oC results in accumulation of RE ions near the substrate and segregation to grain surface. Formation of two additional crystalline phases is revealed. One of them, Zn2SiO4, appears at ZnO/Si interface, while another one, Tb2O3, arises at the boundaries of ZnO grains. An amorphous silicate phase enriched with Tb is aslo found at the interface. In the emission spectra, the energy transfer from Tb3+ to Eu3+ is observed in the annealed film only, resulting in the appearance of two sets of Eu-related bands (narrow and wide). It is proposed that the narrow lines are originated from RE ions located in crystalline Tb2O3, while the wide bands are connected with silicate phases. It is assumed that effective energy transfer in additional phases is caused by the decrease of distance between Tb and Eu ions.

O.P3.37
16:30
Authors : Tatsuya Yasuoka, Masahito Sakamoto, Tamako Ozaki, Yuki Tagashira, Li Liu, Giang. T. Dang, Toshiyuki Kawaharamura
Affiliations : School of Systems Engineering Course, Kochi University of Technology; Intelligent Mechanical Systems Engineering Course, Kochi University of Technology; School of Systems Engineering Course, Kochi University of Technology; Intelligent Mechanical Systems Engineering Course, Kochi University of Technology; School of Systems Engineering Course, Kochi University of Technology; School of Systems Engineering Course, Kochi University of Technology; School of Systems Engineering Course & Center for Nanotechnology, Research Institute, Kochi University of Technology;

Resume : Recently, as a wide band gap material Ga2O3, which crystallizes in 5 phases, α-, β-, γ-, ε- and δ-, has attracted much attention. Among these 5 phases, although β-Ga2O3 is most extensively studied currently, α-Ga2O3 with the band gap of 5.3 eV is also gaining momentum. We have developed the solution-based atmospheric pressure Mist Chemical Vapor Deposition (Mist CVD) and α-Ga2O3 thin films can be fabricated easily by Mist CVD while the fabrication is difficult for other deposition methods. Previously, Yao et al. [1] have reported the influence of Cl on fabrication of Ga2O3 thin films but the interaction mechanism was not clear. Thus, in this work, we studied and discussed how HCl affects the growth of Mist-CVD-grown α-Ga2O3 thin films. The films were prepared by the 3rd generation Mist CVD system [2] consisting of two separate mist solution chambers containing i) GaCl3 as the precursor and ii) the mixture of HCl and D.I. water as the supply source of HCl. The supply amounts of Ga and HCl were controlled by changing the carrier gas flow rates and the effects of different Ga and HCl concentrations in the reactor were investigated. The experiment results show that the increase in HCl concentration increased the deposition rate of the α-Ga2O3 thin films when the concentration of Ga was sufficient. Furthermore, it was found that HCl could also affect the crystal properties of the α-Ga2O3 thin films. I would like to introduce this work in details and discuss it in this conference. [1] Y. Yao et al., Mater. Res. Lett. 6(5), 268-275 (2018) [2] G. T. Dang, T. Yasuoka, Y. Tagashira, T. Kawaharamura et al., Appl. Phys. Lett. 113, 062102(2018)

O.P3.38
16:30
Authors : Osama M. Ibrahim
Affiliations : Mechanical Engineering Department, College of Engineering and Petroleum, Kuwait University

Resume : The objective of this project is to investigate the formation and adhesion of a protective aluminum-oxide layer on the surface of Iron-Chromium-Aluminum (Fe-Cr-Al) alloy. The oxide scale layer was developed using thermal oxidation. Thermogravimetric Analyses (TGA) were done to examine the development of the thin oxide layer. The first sample was tested for 4 hours; while the second sample was tested for 72 hours. Both samples gained weight due to oxidation. Scanning electron microscope (SEM) images show that 4 hours of heat treatment result in the formation of predominantly alumina platelets like and whiskers. After 72 hours of heat treatment, however, the surface of the oxide scale layer becomes smooth and uniform. Following vibration and minimum handling of the two samples, peeling or spalling of the protective oxide layer was observed. Energy Dispersive spectroscopy (EDS) analysis of the heat-treated samples of Fe-Cr-Al sintered metal fibers confirmed the high aluminum content on the surface of the protective oxide layer and the low aluminum content on the exposed base metal alloy surface.

O.P3.39
16:30
Authors : Hansaem Jang, Jaeyoung Lee
Affiliations : (a) Electrochemical Reaction & Technology Laboratory (ERTL), School of Earth Sciences and Environmental Engineering (SESE), Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea; (a) ERTL, SESE, GIST, Gwangju 61005, South Korea, (b) Ertl Center for Electrochemistry and Catalysis, GRI, GIST, Gwangju 61005, South Korea

Resume : Titanium (Ti) electrodes coated with particular metal oxides such as iridium oxides (IrOx) are regarded as ‘dimensionally stable anodes’ due to their durability in harsh conditions. Electrodeposition is one of the most widely selected techniques for coating IrOx on the surfaces of electrical conductors. The precursor solution is generally made to be basic in which acidic condensation of IrOx is avoided. This condition, however, leads to the formation of a compact titanium oxide (TiO2) layer when titanium is used as a substrate. TiO2 acts as an insulator and hinders the deposition of IrOx on the substrate surface. When depositing IrOx anodically on Ti substrate, it is therefore of great importance to control two competing anodic oxidation reactions: IrOx electrodeposition versus Ti anodization. In this presentation, we propose the electrodeposition mechanism of IrOx on Ti and show the conditions required for successful electrodeposition.

O.P3.40
16:30
Authors : Sangmin Jeong, Tri Khoa Nguyen, Jong-sang Youn, Inhwan Oh, Hari Kang, Ki-Joon Jeon
Affiliations : Department of Environmental Engineering, Inha University, Incheon 402-751, Korea

Resume : In recent year, the best catalytic substances for hydrogen evolution reaction (HER) has been known as Pt-group metals, which are expensive and rare to exist in nature to restrain its commercial applications. Transition metal, such as Copper, Nickel, Cobalt, and Titanium etc. have been considered as one of the most promising candidate for HER applications due to their high hydrogen bond energy and current density, which is similar with Pt catalyst. In this work, we synthesized a low-cost catalyst in Transition metal, namely Ni doped TiO2-C/Cu foil for HER, using a UV assisted method on the Sol-solution. The morphological properties, optical properties, and elemental bondings of Ni doped TiO2-C/Cu was investigated using scanning electron microscope (SEM), Raman spectroscopy, and X-ray photoelectron (XPS), respectively. The HER performance of Copper-based electrode was characterized with linear sweep voltammetry(LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) using an Ivium electrochemical station. The comparison of Ni doped TiO2-C/Cu electrode electrochemical properties with that of Pt and TiO2-C/Cu were studied to clarify the excellent HER performance of Copper-based electrodes. This research was supported by the Nano•Material Technology Development Programthrough the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2016M3A7B4904328).

O.P3.41
16:30
Authors : Ye. Venger (1), N. Korsunska (1), L. Melnichuk (1), O. Melnichuk (2), X. Portier (2), L. Khomenkova (1)
Affiliations : (1) V. Lashkaryov ISP of NAS of Ukraine, 45 Pr. Nauky, 03650, Kyiv, Ukraine; (2) Mykola Gogol State University of Nizhyn, 2 Hrafska Str., Nizhyn 16600, Ukraine; (3) CIMAP/ENSICAEN/Normandie Université/CEA/CNRS, 6 Blvd Marechal Juin, 14000 Caen, France

Resume : ZnO films are widely used in light emitting devices, biological sensors, acoustic devices, etc. The important parameters, determined further applications of such films, are their conductivity, carrier concentration and mobility. However, in most cases the direct methods give controversial results for textured films. Therefore, the development of non-destructive methods for the monitoring of the parameters of such films is important. Recently, we have presented the application of infrared (IR) spectroscopic methods for the determination of mentioned above parameters of ZnO films grown on dielectric substrates. In this report, the results obtained for textured ZnO films grown on Si substrates by magnetron sputtering will be presented. The films were studied by means of spectroscopic ellipsometry, AFM, TEM and external IR reflection. It was observed that the shape of IR reflection spectra in ZnO "residual rays" range depends significantly on film thickness and on growth conditions. The position of IR reflection maximum was found to be coincided with the frequency of ZnO TO phonon, indicating a slight deviation of the growth direction of the ZnO film from perpendicularity to Si substrate, as well as the uniformity of the orientation of the ZnO columns. These results were supported by the microscopic studies. The decrease of the intensity of the reflection maximum and its broadening was explained by the manifestation of the phonon- and plasma-related subsystems in ZnO "residual rays" range. For the analysis of IR spectra, it was proposed a theoretical model considered the structural quality and doping level of Si substrate, as well as the phonon and plasmon-phonon interaction of the ZnO film with underlying substrate. Using this model for the simulation of experimental IR spectra, carrier concentration and mobility, as well as film conductivity were extracted. The method developed here can be applied for determination of the parameters of various textured films grown on semiconductor substrates.

O.P3.42
16:30
Authors : Halil Arslan
Affiliations : Andris Azens, Martins Zubkins, Juris Purans

Resume : Although doped ZnO thin films are promising n-type TCO materials, obtaining p-type ZnO thin films is an important milestone in the development of transparent electronics. Recently we have developed p-type ZnO-IrO2 thin films [1,2] and compared with the published theoretical models. Unfortunately, iridium is a very expensive material. Therefore, alternative doping element will be greatly demanded. In the scope of this research we are aiming to develop innovative ZnO:Y (YZO) and multilayers ZnO/YO/ZnO (DMD and DM) by reactive high power impulse magnetron co-sputtering (R-HiPIMS) technology. Only recently [3], it was discovered new phase solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y2+ (4d1) was synthesized in a form of epitaxial thin film by means of pulsed laser deposition means. In contrast with Y2O3, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10-1 to 103 Ω-1cm-1 was attributed to the presence of oxygen vacancies serving as donor of electron. To understand the local electronic and atomic structures in conjunction with their physical-chemical properties advanced in-lab techniques such as XRD, Raman and SEM will be performed. References 1. M. Zubkins, et al., Phys. Status Solidi C 11, 1493 (2014). 2. M. Zubkins, et al, IOP Conf. Series: Materials Science and Engineering 77, 012035 (2015). 3. Kenichi Kaminaga,et al.. Applied Physic Letters, 108, 122102 (2016)

O.P3.43
16:30
Authors : Petr Novák (1), Tomáš Kozák (2), Petra Šotová (1), Jan Očenášek (1), Rostislav Medlín (1), Marie Netrvalová (1)
Affiliations : (1) New Technologies – Research Centre, University of West Bohemia, Plzeň, Czech Republic; (2) Department of Physics and NTIS - European Centre of Excellence, University of West Bohemia, Plzeň, Czech Republic

Resume : Fabrication of inorganic transparent conductive oxides on polymer substrates has been of increasing interest due to their potential applications in the field of flexible electronics. Nevertheless, the brittleness of inorganic thin films often results in a failure of the flexible electronic devices caused by strains formed during stretching, folding or bending. The higher the film thickness, the lower is the strain required to initiate cracks in the film. Thus, achieving the appropriate characteristics at the lowest possible film thickness is very important. Aluminum doped zinc oxide (AZO) has attained prominence as being a very good transparent conducting oxide for optoelectronics and photovoltaic applications. It is considered a cheap and non-toxic alternative to preferably used Indium tin oxide films. Nevertheless, the reduction in the AZO film thickness leads to a significant increase in its resistivity. The present work deals with the investigation of the thickness dependence of electrical properties of AZO films prepared at substrate temperature 100°C. The experimentally determined parameters together with the model allow to identify electrical properties at individual thickness layers and correlate them with the film structure observed at a given distance from the substrate. The presented approach describes very well the inferior electrical conductivity of very thin films, as well as the conductivity saturation for larger film thickness.

O.P3.44
16:30
Authors : Tien-Chai Lin1, Bai-Jhong Jheng1, Nien-Yu Wu2, Wen-Chang Huang2, 3*
Affiliations : 1 Department of Electrical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 2 Green Energy Technology Research Center, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 3 Department of Electro-Optical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC

Resume : RF magnetron sputtering deposition of vanadium pentoxide (V2O5) thin films on ITO glass substrate with various Ar/O2 partial pressure for electrochromic applications were presented in the research. The partial pressures of the Ar:O2 is 5:1, 10:1, 15:1 and 20:1, respectively. It shows that the deposition rate of the film decrease with the increase of oxygen partial pressure, and it also make its surface morphology become rough. This is due to “target poison effect” with the increase of oxygen flow during deposition process. For the electrochromic property of the film, a higher transparent difference, △T between colored/bleached processes of 43.8 % is found at the sample of partial pressure ratio of Ar/O2=15/1. It also shows a high charge storage capacity of 64.63 mC/cm2. Both these two values are better than that of the sample without oxygen flow.

O.P3.45
16:30
Authors : Pussana Hirunsit,*[a] Takashi Toyao,[b,c] S. M. A. Hakim Siddiki,[b] Ken-ichi Shimizu,[b,c] Masahiro Ehara[c,d]
Affiliations : [a] National Nanotechnology Center (NANOTEC), Thailand Science Park, Patum thani 12120, Thailand; [b] Catalysis Research Center, Hokkaido University, Kita 21 Nishi 10, Kita-ku, Sapporo, Hokkaido 001-0021, Japan; [c] Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto 615-8520, Japan; [d] Institute for Molecular Science, Nishigo-naka 38, Myodai-ji, Okazaki, Aichi 444-8585, Japan;

Resume : The Nb2O5 surface catalyzes the amidation of carboxylic acids with amines via Nb5+ Lewis acid activation of the C=O group. In this work, DFT calculations were applied to theoretically investigate the C=O bond activation of a model carboxylic acid (acetic acid) on gamma-Al2O3(110), anatase TiO2(101), and T-Nb2O5(100) surfaces. The adsorption sites, adsorption energies, reaction energy barriers, electronic properties, and vibrational frequency of acetic acid were examined in detail. It was found that the bond activation of the carbonyl group is most efficient on Nb2O5, although the adsorption energy is larger on Al2O3 and TiO2. The most C=O bond activation on Nb2O5 leads to the lowest energy barrier of C-N bond formation during amidation. The Nb2O5 surface also show tolerance to methylamine and water molecules, comparing to Al2O3 and TiO2 surfaces. These crucial factors contribute to the highest amidation catalytic reactivity on Nb2O5. Furthermore, the position of the mean DOS of the d-conduction band of the active metal site relative to the Fermi energy level correlates well with the efficiency in the C=O bond activation and, consequently, the catalytic activity for amidation. These results suggest that, unlike a classical understanding of strong acid sites of metal oxide surfaces, interaction of a carbonyl HOMO with a metal unoccupied d-orbital, or, in other words, covalent-like interaction between a carbonyl group and metal adsorption site, is relevant to the present system.

O.P3.46
16:30
Authors : M. A. Curado1,2, H. V. Alberto2, R. C. Vilão2, A. F. A. Simões2, J. M. Gil2, T. Prokscha3, A. Suter3, Z. Salman3, J. M. V. Cunha1,4, P. A. Fernandes1,6,7, O. Donzel-Gargand1,5, A. Hultqvist5, M. Edoff5,J. Leitão4,6, P. M. P. Salomé1,4
Affiliations : 1)INL – International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal 2)CFisUC,Departamento de Física, Universidade de Coimbra, 3004-516 Coimbra, Portugal 3)Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 4)Departamento de Física, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal 5)Ångström Laboratory, Solid State Electronics, Ångström Solar Center, Uppsala University, SE-751 21 Uppsala, Sweden 6)I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal 7)CIETI, Departamento de Física, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Porto 4200-072, Portugal

Resume : Cu(In,Ga)Se2 (CIGS) thin film solar cells currently achieve a record power conversion efficiency of 22.9 %. For further increases, many properties still have to be implemented and improved. One of them is the use of interface passivation layers. These can reduce the number of electrically active defects and/or lead to an electric field caused by fixed charges that reduce interface recombination. However, this technology is still in an early stage and a better understanding of the underlying physics is required. Muon spin spectroscopy (µSR) is a technique that probes the interface properties of complex multinary semiconductors. This probing capability is due to the muon sensitivity to the presence of charge carriers and to the interface local structure. This technique will be complementary to others such as SEM, Raman spectroscopy and TEM for morphological characterization; XPS and EDS to know the chemical composition; and photoluminescence spectroscopy and electrical measurements with Metal-Insulator-Semiconductor (MIS) to characterize dominant defects. We investigate a CIGS/Al2O3 (grown by Atomic Layer Deposition) interface and compare it with a reference CIGS/CdS interface. A clear effect is observed and we relate it to interface charged surface defects. Furthermore, we explore the morphological and chemical properties of the different interfaces pointing to small differences that may be responsible for the observed muon results.

O.P3.47
16:30
Authors : Byung-Hyuk Jun, In-Hwan Cho, Chan-Joong Kim
Affiliations : Neutron Utilization Research Division, Korea Atomic Energy Research Institute (KAERI), Republic of Korea

Resume : The effects of lithium doping on the electrical properties and ageing effect of ZnSnO (ZTO) thin films fabricated on a SiO2/p+-Si substrate using a sol–gel process were investigated. As the Li content increased from 0 to 15 at%, the saturation mobility increased until 3 at% of Li and then decreased. The sub-threshold swing and on/off ratio were improved with the increase in Li content. In addition, Li (3 at%)–ZTO showed the smallest threshold voltage change of 2.52 V among the TFTs in a positive bias stress (PBS) test. To observe the influence of Li on the ageing effect of TFTs, unpassivated Li–ZTO TFTs were stored under ambient conditions for 120 days. As a result of comparing the electrical characteristics of Li–ZTO TFTs after different durations of air exposure, the on/off ratio and sub-threshold swing of the Li (7 at%)–ZTO sample were almost unchanged when compared to those of ZTO. An XPS analysis of the O 1s core level showed that the relative area of oxygen vacancies decreased from 27.2 to 19.6% as the Li content increased from 0 to 15 at%. A spectroscopic ellipsometer analysis showed that Li (3 at%)–ZTO had the smallest optical band gap of 3.68 eV. From the result of the band alignment, it was confirmed that the Fermi level of Li (3 at%)–ZTO was located at the closest position to the conduction band minimum. Despite the reduction of the oxygen vacancy, the reason for the increasing electron concentration was due to the Li atom being preferentially located in the interstitial site, which released the free electron in the ZnO matrix. As a result, Li (3 at%)–ZTO showed improved electrical properties in the saturation mobility and PBS with stability under an ambient environment.

O.P3.48
16:30
Authors : Malek Atyaoui , Tayssir Ben Amara , and Hatem Ezzaouia
Affiliations : Laboratoire des nanostructures, des semi-conducteurs et des technologies avancées, Centre des recherches et des technologies de l’énergie, technopole de Borj-Cédria, PB :95,Hammam Lif 2050, Tunisia

Resume : : The main problems preventing wide spreading of solar cells as alternative energy sources are their high cost and low efficiency. Efficiency of solar cells based on semiconductors materials is limited due to high electrical and optical losses and to recombination process. Therefore and in order to surmount these problems, we propose in this work to use ZTO nanoparticles deposited on porous silicon layer as antireflection coatings. We found that the formed layer decrease the optical losses which consequently contribute to the improvement in the conversion efficiency of solar cells.

O.P3.49
16:30
Authors : Cheol Park1, Jae-Wook Kang2, Sukeun Yoon1, Jihoon Kim1*.
Affiliations : Division of Advanced Materials Engineering, Kongju National University, Cheonan, Chungchungnam 31080, Korea. Department of Flexible and Printable Electronics, Chonbuk National University, Chonbuk 54896, Korea.

Resume : Aluminum-doped Zink Oxide (AZO) transparent conducting oxide (TCO) films were successfully prepared by a low temperature spin-spray deposition (SSD). In this work, we have performed a meticulous investigation on the SSD parameters and the effect of Al doping concentration on the electrical and optical properties of the films. The SSD temperature was maintained at less than 100 ºC, which allows flexible substrates. The SSD AZO films exhibited a high transference ~85% with a promising electrical property. The SSD AZO films were characterized by various analytical instruments; UV-Spectrometer, X-ray diffraction, field emission scanning electron microscopy, and intra coupled plasma spectroscopy. Photovoltaic devices using the SSD AZO films were fabricated to verify the validity of the SSD AZO films as TCO electrodes.

O.P3.50
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Oxide interfaces : -
08:30
Authors : F. Miletto Granozio
Affiliations : CNR-SPIN, UOS Napoli

Resume : Two-dimensional electron gases (2DEGs) at oxide interfaces, as LaAlO3/SrTiO3 (LAO/STO) and its several variants, show multiple functional properties of major physical interest, including a high low-temperature mobility, superconductivity, a large Rashba spin-orbit coupling, an exceptionally large spin-to-charge conversion efficiency and a yet controversial magnetic ground state. Such properties are tunable under external control parameters, as electric field effect. In a number of experiments briefly described in the talk, we will first show the capability of tailoring unexpected samples properties by pushing growth control of our crystalline interfaces to the highest level. We will then focus on the control of strain relaxation, selecting the conditions in which an epitaxially strained state is retained much above the expected critical thickness. In this regime, strain relaxation is highly disruptive and surprisingly causes the formation of freestanding LAO/STO membranes, which preserve the metallic properties of macroscopic LAO/STO samples. Such membranes can be manipulated, contacted and employed as elements of microscopic circuits on a generic surface.

O.4.1
09:00
Authors : Toni Markurt 1, Martina Zupancic 1, Martin Albrecht 1, Wahib Aggoune 2, Claudia Draxl 2, Young Mo Kim 3, Youjung Kim 3, and Kookrin Char 3
Affiliations : 1 Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin, Germany; 2 Humboldt-Universität zu Berlin, Institut für Physik und IRIS, Zum Großen Windkanal 6, 12489 Berlin, Germany; 3 Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, South Korea

Resume : Two-dimensional electron gases (2DEG) at the interface between two wide bandgap oxide materials have attracted a lot of interest in the past decade, both due to the promise to realize novel electronic devices and also because of interesting new physical phenomena. In case of the famous prototypical LaAlO3/SrTiO3 system it is believed that the polar discontinuity and an electronic reconstruction at the n-type LaO-TiO2 interface are the origin of the 2DEG. Recently, BaSnO3 is intensively investigated due to its highest electron mobility at room temperature (~300 cm2/Vs) among other transparent conductive oxides even for a doping concentration of 1E20 cm-3. Similar to the LaAlO3/SrTiO3 case a 2DEG is observed when growing a LaInO3 film on a BaSnO3 buffer. By means of transmission electron microscopy we found that an interface roughness of even several nanometers and a variation of the cation termination at the LaInO3/BaSnO3 interface do not prevent the formation of the 2DEG. This surprising result raised the assumption that a more fundamental mechanism independent of the interface chemistry is responsible for the appearance of the 2DEG. Further analysis showed that the change of the tilt of oxygen octahedra from the cubic BaSnO3 (no tilt) to the bulk value of LaInO3 (5.5°) does not occur abruptly at the interface, but gradually within a few monolayers in LaInO3. The suppression of octahedral tilt leads to an interfacial polarization which in turn explains the formation of the 2DEG.

O.4.2
09:15
Authors : J. Wolfman*, A. Ruyter*, B. Negulescu*, P. Andreazza†, C. Autret*, X. Wallart‡
Affiliations : * GREMAN, UMR7347 CNRS, Université de Tours, Parc de Grandmont, F-37200 Tours, France † ICMN, UMR 7374 CNRS, Université d’Orléans, 1b rue de la Férollerie, F-45071 Orléans, France ‡ Univ. Lille, CNRS, Centrale Lille, ISEN, Univ. Valenciennes, UMR 8520 -IEMN, F-59000 Lille, France

Resume : Metal/ferroelectric/metal (M/FE/M) junctions suffer from two interface controlled limiting factors: an interface FE dead layer, due to depolarizing field, and a high leakage current due to insufficient Schottky barrier height (SBH). Band engineering, developed in the 70s, is an effective way to control SBH at M/semiconductors junctions. Since then DFT calculations have shown that interface chemical bounding plays a major role on both SBH [1] and polarization stabilization [2] at M/FE. We propose to apply these concepts to promote electrical polarization and control the SBH at the interfaces of epitaxial oxide FE junctions using interface engineering by combinatorial pulsed laser deposition. Modulation of the interface composition over a few monolayers (ML) tunes the FE’s electronic affinity and band gap, and the electrode’s work function and carrier doping, parameters which control bands alignment at the interface. We report here on La0.7Sr0.3MnO3/La1-ySryMnO3 (3ML)/SrTiO3 and La0.7Sr0.3MnO3/Ba1-xSrxTiO3 (1-3ML)/SrTiO3 junctions. Photo electron spectroscopies (XPS/UPS) showed a continuous La1-ySryMnO3 work function variation with the carrier content y. Local electrical UHV SPM characterizations (IVs, KPM), carried out without sample exposure to air, revealed a non-monotonous and correlated dependence of both the threshold voltage and the Kelvin potential. Effects of the interface chemical modulation on the band structure will be discussed versus composition and thickness. References: [1] R. Tung, Mat. Sci. and Eng. R 35, 1 (2001) [2] M. Stengel et al., Nat. Mat. 8, 392 (2009)

O.4.3
09:30 Cofee break    
 
Advanced characterization : -
10:00
Authors : B.Warot-Fonrose, C.Gatel, R.Arras, M.J. Casanove
Affiliations : CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse

Resume : Magnetic or electronic properties of oxide thin films depend on the local structure and chemistry of the layers. For instance, cation ordering, antiphase boundaries or strain state can modify the saturation magnetization or the coercive field. Transmission electron microscopy (TEM) is one of the suitable technique to get access to structural and chemical mapping at the nanometer scale. The combination of several TEM techniques with atomic resolution is available to elucidate the correlation between structure/chemistry and physical properties. The first study will focus on ferromagnetic spin filters that rely on the spin-dependent transmittance of ferromagnetic tunnel barriers due to the existence of an exchange-split band gap. Several requirements have to be fulfilled by the barrier to be efficient: the magnetism has to remain important even at room temperature and for very thin thickness (down to 3nm) to allow for spin-dependent tunnel transport. The second study will focus on the SrTiO3 / LaAlO3 system for transport applications. The occurrence of a conductive behaviour of the LaAlO3/SrTiO3 interface is attributed to the advent of an electronic reconstruction above a critical thickness of 4 u.c. of LaAlO3, in order to compensate the charge discontinuity at the interface between a polar (LaAlO3) and a non-polar (SrTiO3) materials. Various parameters are likely to affect the properties of this interface such as the change in the nature of the substrate, the application of a stress field or the introduction of slight chemical modifications in the layer or at the interface.

O.5.1
10:30
Authors : Hongguang Wang, Vesna Srot, Gennadii Laskin, Jochen Mannhart, Peter A. van Aken
Affiliations : Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany

Resume : Quantum nanostructures open a window for solid-state research due to their fascinating possibilities to create novel electron systems. Electron states and correlation of quantum matters can be influenced by changing dimensions because of size quantisation effects. Among them, the zero-dimensional electron system (artificial atoms or quantum dots) is a cutting-edge research field with remarkable scientific advances. Confinements in three dimensions can bring intriguing electrical and optical properties, which play a key role in novel applications like fabrication of quantum photonic devices. Thus, their nanoscale structural explorations are essential for understanding the underlying physical properties, but rather challenging and rarely reported. Here, pulsed layer deposition has been used to epitaxially grow SrRuO3 thin films on SrTiO3 substrates, which are ultimately patterned to artificial atoms by using ion milling and e-beam lithography. By using aberration-corrected scanning transmission electron microscopy, we have performed atomic-scale microstructural investigations of the patterned SrRuO3 artificial atoms with different diameters. Atomically resolved high-angle annular dark-field imaging of the atoms’ cross-section enables us to study the evaluation of the strain states by applying geometry phase analysis. We unambiguously demonstrate that epitaxial strain of SrRuO3 artificial atom is gradually released while reducing the size of SrRuO3 artificial atoms.

O.5.2
10:45
Authors : Hendrik Wulfmeier1, Silja Schmidtchen1, Thomas Defferriere2, Harry L. Tuller2, Holger Fritze1
Affiliations : 1 Clausthal University of Technology, Institute of Energy Research and Physical Technologies, Am Stollen 19 B, D-38640 Goslar, Germany; 2 Massachusetts Institute of Technology, Department of Materials Science and Engineering, 77 Massachusetts Ave, Cambridge, MA 02139, USA

Resume : Expansion of oxide thin films induced by changes in temperature and/or oxygen partial pressure pO2, known as chemical expansion, may contribute to the degradation of high-temperature fuel cells or enable a new generation of very high-temperature actuators with operating temperatures above 500°C. The phenomenon is investigated using thin-film praseodymium cerium oxide (Pr0.1Ce0.9O(2-δ), PCO) as model system. The chemical expansion of 300 nm to 2 µm thick films is measured by laser vibrometry at temperatures up to 800°C. The films are deposited onto yttria stabilized zirconia (YSZ) substrates that enable removal of oxygen by application of moderate pump voltages of up to about 1 V. The chemical expansion is correlated with the oxygen deficit δ that determines, in turn, the valence state of the Pr cations in the film. PCO is a favorable model material as it reversibly releases a substantial amount of oxygen under readily accessible oxygen partial pressures close to that of air. Chemical expansion also leads to lateral stress in the PCO film that leads to measurable deflection of the YSZ substrate. The superposition of expansion and deflection, i.e. the total vertical displacement, is investigated in-situ by high-temperature laser Doppler vibrometry (LDV). The measured chemical expansion correlates well with defect chemical and kinetic models and their expected dependence on temperature, oxygen pumping time and pumping voltage.

O.5.3
11:15 Plenary session 1    
12:30 Lunch    
 
Functional oxides : -
14:00
Authors : Zhong Lin WANG
Affiliations : School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, USA; Beijing Institute of Nanoenergy and Nanosystems, CAS, Beijing, 100083, China

Resume : Piezoelectricity, a phenomenon known for centuries, is an effect that is about the production of electrical potential in a substance as the pressure on it changes. For wurtzite structures such as ZnO, GaN, InN and ZnS, due to the polarization of ions in a crystal that has non-central symmetry, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. The effect of piezopotential to the transport behavior of charge carriers is significant due to their multiple functionalities of piezoelectricity, semiconductor and photon excitation. By utilizing the advantages offered by these properties, a few new fields have been created. Electronics fabricated by using inner-crystal piezopotential as a “gate” voltage to tune/control the charge transport behavior is named piezotronics, with applications in strain/force/pressure triggered/controlled electronic devices, sensors and logic units. This effect was also extended to 2D materials such as MoS2. Piezo-phototronic effect is a result of three-way coupling among piezoelectricity, photonic excitation and semiconductor transport, which allows tuning and controlling of electro-optical processes by strain induced piezopotential. The objective of this talk is to introduce the fundamentals of piezotronics and piezo-phototronics and to give an updated progress about their applications in energy science (LED, solar) and sensors (photon detector and human-CMOS interfacing). [1] Wu, et al Science, 340 (2013) 952-957. [2] Pan et al. Nature Photonics, 7 (2013) 752-758. [3] Z.L. Wang Nano Today, 5 (2010) 540-552. [4] Yang et al. Nano Letters, 11 (2011) 4012–4017. [5] Wu et al. Nature, 514 (2014) 470-474. [6] W.Z. Wu and Z.L. Wang, Nature Review Materials, 1 (2016) 16031 [7] “Piezotronics and Piezo-phototronics with the Third-generation Semiconductors”, MRS Bulletin, 43 (2018) 922-926

O.6.1
14:30
Authors : M. Gaudin, M. M. Villamayor, A. Bailly, A. Ramos, P. Bouvier, S. Grenier, M. Chaker, L. Magaud, L. Laversenne
Affiliations : Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France; EMT, INRS, Varennes, Canada; Institut Néel, CNRS, Grenoble, France; Institut Néel, CNRS, Grenoble, France

Resume : Vanadium dioxide (VO2) has the remarkable property of exhibiting a first order insulator to metal transition (MIT) at a temperature T(MIT) close to ambient temperature (68°C). It is characterized by a crystallographic transformation from the high-temperature tetragonal rutile (R) to low-temperature monoclinic (M) structure and by a change in resistivity (of the order of 4 to 5 orders of magnitude) and optical transmission in the near-infrared range under the effect of an external stimulus such as heat, stress, current or electrical voltage. These properties give the thin film an ideal choice for applications in electronic devices as intelligent materials. Mechanism involved in decreasing T(MIT) in VO2 by selective doping is still a matter of debate. Our work focuses in the understanding of the correlation between W doping and the T(MIT), the electronic and geometrical structures around V atoms in V(1-x)WxO2 pulsed laser deposited thin films. Electronic (resistivity by four points probe) and structural (Raman spectroscopy) measurements revealed a reduction in T(MIT) by 35 to 60°C by increasing W doping from 1.3 to 3.3%. Clear evidence of substitutional W-doping on the crystallographic and electronic structure is observed both on the XANES and XAFS signatures.

O.6.2
14:45
Authors : Carla M. Palomares García [1], A. Di Bernardo [1], G. Kimbell [1], M. E. Vickers [1], Y. Yasui [2], B. Kim [3], S. Komori [1], Y. Maeno [2], T. W. Noh [3], J. W. A. Robinson [1].
Affiliations : [1] Department of Materials Science & Metallurgy, University of Cambridge, United Kingdom; [2] Department of Physics, Graduate School of Science, Kyoto University; [3] Institute of Basic Science, Center for Correlated Electron Systems, Seoul National University.

Resume : Bulk p-wave triplet superconductivity is rare, but the important highly unconventional superconductor Sr2RuO4 (SRO) is the best known example and has been the subject of extensive study over the past decade and half [1]. Bulk p-wave superconductivity is extremely sensitive to electron scattering which has meant that the growth of superconducting SRO thin-films has been extremely challenging [2,3]. Two papers report superconductivity in SRO thin-films prepared by pulse laser deposition (PLD) [4,5] and several groups by molecular beam epitaxy (MBE) [6,7]. However, in all reports the growth parameter space for achieving superconductivity is narrow and although high purity is essential, the key underlying microstructural defects that suppress superconductivity remain unknown. In this talk we report the systematic growth of superconducting SRO thin-films by PLD from a Ru-rich SRO single crystal target and correlate suppression of superconductivity to in-plane (tilt and edge dislocations) and out-of-plane (inhomogeneous strain) structural defects. The results offer a breakthrough in understanding and enable the reliable, routine, growth of SRO thin-films. [1] Maeno, Y.et al. Evaluation of Spin-Triplet Superconductivity in Sr2RuO4. J. Phys. Soc. Japan 81, 1–29 (2012). [2] Mackenzie, A. P. et al. Extremely Strong Dependence of Superconductivity on Disorder in Sr2RuO4. Phyisical Rev. Lett. 80, 161–164 (1998). [3] Mao, Z. Q. Suppression of superconductivity in Sr2RuO4 caused by defects. Phys. Rev. B 60, 610–614 (1999). [4] Krockenberger, Y. et al. Growth of superconducting Sr2RuO4 thin films. Appl. Phys. Lett. 97, 082502 (2010). [5] Cao, J. et al. Enhanced localized superconductivity in Sr 2 RuO 4 thin fi lm by pulsed laser deposition. Supercond. Sci. Technol. 29, 1–6 (2016). [6] Uchida, M. et al. Molecular beam epitaxy growth of superconducting Sr2RuO4films. APL Mater. 5, 1–6 (2017). [7] Nair, H. P. et al. Demystifying the growth of superconducting Sr2RuO4 thin films. APL Mater. 6, (2018).

O.6.3
15:00
Authors : A. Ruiz-Caridad1, G. Marcaud1, J. M. Ramirez1, J. Zhang1, L. Largeau1, T. Maroutian1, S. Matzen1, C. Alonso-Ramos1, S. Collin1, G. Agnus1, S. Guerber1,2, C. Baudot2, F. Boeuf2, E. Duran-Valdeiglesias1, V. Vakarin1, E. Cassan1, D. Marris-Morini1, P. Lecoeur1, L. Vivien1.
Affiliations : 1 Centre de Nanosciences et Nanotechnologies (C2N), Univ Paris Sud, CNRS UMR 9001, Université Paris-Saclay, Palaiseau, 91120, France. 2 Technologie R&D, STMicroelectronics, SAS, 850 rue Jean Monnet – 38920 Crolles, France

Resume : Functional oxides are a very interesting class of materials due to their singular characteristics comprising superconductivity, magnetism, ferroelectricity, catalytic activity, resistive switching or electro-optic effects, among others [1]. Yttria-Stabilized Zirconia’s (YSZ) structural and optical properties include thermal and chemical stability; a refractive index of about 2.14, a large optical energy bandgap (~5 eV) that prevents two photon absorption (TPA) in the near and mid-IR; transparency from visible to mid-IR and a good Kerr effect. Moreover, it has also been reported as an interesting material to be combined with either silicon or other platforms including sapphire, providing an effective buffer layer for other epitaxial functional oxides [2]. By means of material engineering, manipulation of these properties to build active reconfigurable elements in complex systems will lead to new functionalities including on-chip optical amplifiers that may be instrumental for a large number of nanophotonics applications. We recently demonstrated YSZ waveguides with propagation losses as low as 2 dB/cm in telecom wavelength range [3]. Based on these encouraging preliminary results, we have recently explored the possibility to introduce active rare-earth dopants into YSZ to demonstrate on-chip optical waveguides amplifiers based on YSZ. Yttrium-to-erbium substitution can be performed in the YSZ crystal, enabling a nearly perfect allocation of Er ions in the host matrix. For this purpose, we have studied structural and optical properties of Er3 ions in different platforms using a multilayer approach and deposited by Pulsed Laser Deposition (PLD) technique. We prove outstanding luminescence around λ = 1.54 µm, in correspondence with the C-band of telecommunications and in the visible range under a continuous-wave pump laser excitation at about 980 nm and 1480 nm. At the shadow of those results, we explored light amplification of Er-doped thin layers deposited on a SiN passive photonic platform. [1]. Lorenz, M., et al. Journal of Physics D: Applied Physics, 49, 433001 (2016). [2]. Jun, S., et al. Appl. Phys. Lett. 78, 2542 (2001). [3]. Marcaud, G., et al. Rev. Phys. Materials 2, 035202 (2018).

O.6.4
15:15
Authors : A. Quattropani1, D. Stoefffler2, C. Lefèvre2, J.L. Rehspringer2,G. Schmerber2, G. Versini2, M. Rastei2, B. Kundys2, S. Colis2, A. Dinia2, T. Fix 1, A. Slaoui1
Affiliations : 1 CNRS and Université de Strasbourg, ICube Laboratory, 67037 Strasbourg, France 2 CNRS and Université de Strasbourg, Institut de Physique et Chimie des Matériaux de Strasbourg, F-67034 Strasbourg, France

Resume : Ferroelectric (FE) materials are under intense scrutiny for photovoltaic applications (PV), following the demonstration of above 8% conversion efficiency in FE-based solar cells [1]. In these cells, there is no need for a p-n junction because the electric polarization from ferroelectricity is responsible for the current flow. The key issue for the development of oxide absorbers for PV is their bandgap that is generally above 3 eV. In this work, we produced Bi2FeCrO6 (BFCO) oxide materials by pulsed laser deposition (PLD). The structural, optical and electrical properties are presented. High quality epitaxial growth and phase-pure films are demonstrated by X-ray diffraction. We have studied the evolution of parameters such as the bandgap versus the growth conditions, proving that it can be adjusted from 1.9 to 2.6 eV [2]. Resonant X-ray diffraction is performed at ESRF to investigate the origin of the variation of the bandgap. The ferroelectric properties are investigated by piezoresponse force microscopy (PFM). We observe that light influences the state of polarization of BFCO. Finally, devices based on BFCO are fabricated and their photovoltaic properties are analysed. References: [1] R. Nechache, C. Harnagea, S. Li, L. Cardenas, W. Huang, J. Chakrabartty, F. Rosei, Nature Photonics, 2015, 9, 61 [2] A. Quattropani, D. Stoeffler, T. Fix, G. Schmerber, M. Lenertz, G. Versini, J. L. Rehspringer, A. Slaoui, A. Dinia and S. Colis, Journal of Physical Chemistry C 122, 1070 (2018)

O.6.5
15:30
Authors : M. Nistor
Affiliations : National Institute for Lasers, Plasma and Radiation Physics (NILPRP), L22, PO Box. MG-36, 77125 Bucharest-Magurele, Romania

Resume : Oxide thin films continue to attract paramount attention due to the broad range of properties they exhibit for applications. This presentation gives a short review on oxide thin films grown by pulsed electron beam deposition technique (PED) with focus on the correlation between composition, structure and physical properties. We will consider examples of epitaxial undoped and doped oxide thin films that are obtained by PED starting from relatively low substrate temperatures. The tuning of their physical properties is obtained due to the precise control of the growth conditions. In fact, changes in substrate temperature, working gas or pressure lead to strong effects on the optical transparency and/or electrical conductivity. These effects will be discussed in relation with the film composition, evidencing the role played by the dopant and/or oxygen on the oxide film properties. It is therefore possible to obtain by PED either stoichiometric oxide films or oxygen deficient metastable phases. These significant changes lead to pure or nanocomposite oxide thin films with specific characteristics and properties for applications.

O.6.6
16:00 Coffee break    
 
Functional oxides : -
16:30
Authors : Wilfrid PRELLIER
Affiliations : Laboratoire CRISMAT CNRS ENSICAEN

Resume : We have developed a high-throughput method to explore how surfaces of polycrystalline ceramics impact phase formation and epitaxial orientation relationships during thin film growth. Instead of using a single crystal substrates, the combinatorial substrate epitaxy (CSE) involves film deposition on polished surfaces of polycrystals and determination of local epitaxy using electron back-scatter diffraction. After a review of prior observations, our recent work on the development of new electronic materials using CSE will be presented. In each case, targeted new electronic materials will be described along with efforts to stabilize them by CSE. Here, the discussion will include the following composition: BiFeO3, Ca2Mn4 or Dy2Ti2O7. These results further demonstrate the potential of CSE in the design and growth of a wide range of complex functional oxides.

O.7.1
17:00
Authors : M. Becker, F. Michel, F. Kuhl, A. Polity, S. Chatterjee, and P. J. Klar
Affiliations : Institute of Experimental Physics I and Center for Materials Research, Heinrich-Buff-Ring 16, Justus Liebig University Giessen, D-35392 Giessen, Germany

Resume : The sputter deposition of (poly-)crystalline binary oxides seems allegedly simple. However, this is not entirely true, since there exist binaries which as crystalline material only exhibit one stoichiometry and one crystal structure, those which possess different polytypes at one distinct stoichiometry and those which feature crystalline phases at different stoichiometries. The material’s properties and the material’s phase obtained will strongly depend on the synthesis parameters, e.g., gas fluxes, substrate temperature, substrate, etc. Thus, in case of binary systems exhibiting various crystalline phases, changing these parameters allows one to establish phase maps in dependence on the growth parameters. Furthermore, combining several sputter sources in order to perform combinatorial screening of thin film materials allows an additional fine-tuning of the material’s properties and enables the buildup of materials libraries. Such high-throughput screening is also of major economic importance as designed functional materials are behind future key technologies and play an essential role in their evolution. Moreover, buffer layers deposited on the substrate surface prior to the preparation of the actual functional layer might increase the quality of the growth of the functional layer itself or provide a surface triggering a preferential crystal orientation. We present the capabilities of ion-beam bombardment for thin-film processing, especially for deposition of thin films by ion-beam sputtering. Different arrangements of ion sources, targets, and samples are discussed in general terms and the versatileness of ion-beam techniques in the synthesis of thin films and multilayer structures is highlighted by giving several examples on metal oxides: Ion-beam sputtering (IBS) of various binary oxides as well as combinatorial growth of materials libraries of ternary metal oxide systems and highly controlled buffer layer growth.

O.7.2
17:15
Authors : S. Basov1, M. J. Van Bael2, A. Vantomme1, and K. Temst1
Affiliations : 1. Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium 2. Laboratorium voor Vaste-Stoffysica en Magnetisme, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium

Resume : Recently efforts on the growth of magnetic metallic thin films on functional ferroelectric oxides have allowed manipulating magnetism via electric fields, so-called magnetoelectric (ME) coupling, which is attractive for energy-efficient memory device applications. Multiferroic heterostructures, such as Fe/BaTiO3 and Fe/0.7PbMg1/3Nb2/3O3-0.3PbTiO3 (PMN-PT), rely on the large interfacial strain and charge co-mediated ME coupling between the piezoelectric and charge effects in the ferroelectric oxide layer and the magnetostriction in the adjacent ferromagnetic layer. Understanding the contribution of the various interface mechanisms to the detected ME coupling is a challenge in the field of multiferroic heterostructures. In this work, Fe thin films are grown on PMN-PT single-crystal substrates using molecular-beam epitaxy. To discriminate between the various interface effects contributing to the ME coupling, we have developed a new approach in local and quantitative Mössbauer characterization of electric and magnetic field profiles. To this end, the magnetic Fe constituent is enriched with 57Fe probe layers either at or further away from the metal/oxide interface, which enables probing the oxidation state, lattice distortion, and magnetism with sub-nm resolution. The efficiency and flexibility of this technique have been previously demonstrated for Fe/BaTiO3 and Fe/LiNbO3.1,2 [1] S. Couet, et al., Adv. Fun. Mater. 24, 71 (2014) [2] M. Bisht, et al., Adv. Mat. Interfaces 3, 1500433 (2016)

O.7.3
17:30
Authors : Jong-Un Woo, Hyun-Gyu Hwang, Sung-Mean Park, Sahn Nahm
Affiliations : KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, South Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, South Korea; Department of Materials Science and Engineering, Korea University, Seoul 136-701, South Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, South Korea and Department of Materials Science and Engineering, Korea University, Seoul 136-701, South Korea

Resume : In this work, NaNbO3 (NN) thin films were grown on the TiN/SiO2/Si substrate using pulsed laser deposition (PLD) system to realize memristor having synaptic plasticity and meta-plasticity. The NN thin films grown at low temperatures (300oC) exhibited the amorphous phase. The NN thin films exhibited a bipolar resistive switching behavior and it can be explained by the formation and rupture of the oxygen vacancy filaments. This NN films showed the excellent retention properties (> 104 sec) and the reliable endurance properties (> 400 cycles) with a low power consumption. Moreover, the synaptic properties such as spike-timing-dependent-plasticity (STDP), short-term-plasticity (STP), long-term-plasticity (LTP) and spike-rate-dependent-plasticity (SRDP) of the NN ReRAM devices were also obtained in the NN film. The meta-plasticity of biological synapses was also implemented in the NN memristor, including the metaplasticity of STDP. Therefore, the NN memristor could be used as an artificial synapse in neuromorphic computing system.

O.7.4
17:45
Authors : Sherif Ibrahim, Wing Ng, Daniel Mannion, Adnan Mehonic, and Anthony J Kenyon.
Affiliations : Department of Electronic & Electrical Engineering, University College London, Torrington Place, London WC1E 7JE

Resume : In filamentary resistive random access memory (RRAM) devices, the resistance state of the device is changed via formation and annihilation of a conductive filament within the device switching layer (usually an oxide layer). The mechanism responsible for forming this conductive filament is highly dependent of the type of atoms or anions that drift under the applied external bias during the switching process. In extrinsic switching devices, drifted metallic cations from the device electrochemically active top electrode coalesce and form a metallic filament. On the other hand, oxygen vacancies generated by the movement of oxygen anions consolidate to form the conductive filament in intrinsic switching devices. Here, we show that the two mechanisms, and their associated filaments, can coexist in SiOx RRAM devices with Ag top electrodes. This multifilament formation process happens during the device cycling. The nature of the formed filament and its corresponding switching mechanism were probed using resistance vs temperature measurements. The order in which the two mechanisms are initiated is dependent on the polarity of the applied external bias during electroforming and subsequent switching. We will also discuss how to separate the two mechanisms by controlling the oxygen environment of the device during switching.

O.7.5
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Ferroelectric oxides : -
08:30
Authors : J. M. Vila-Fungueiriño(1), A. Gómez (2), Q. Zhang (1,2), D. Sanchez (1), G. Saint-Girons (3), N. Mestres (2), C. Magén (4), J. Gázquez (2), R. Bachelet (3), M. Gich (2), A. Carretero-Genevrier (1) *
Affiliations : Institut d’Electronique et des Systemes (IES), CNRS, Universite Montpellier 2 860 Rue de Saint Priest 34095 Montpellier, France

Resume : The ability to combine standard wafer-scale semiconductor processing with the excellent properties of functional oxides opens the possibility to realize innovative and more efficient devices with high value applications that can be produced at large scale. However, the precise control of interfaces and crystallization mechanisms of dissimilar materials rest extremely challenging. As an example, the scalable and sustainable integration of high quality epitaxial oxide nanostructured thin films on silicon need to be further developed. In this regard, I will present successful strategies that integrate functional oxides nanostructures on silicon via chemical solution deposition (CSD) approach. Divers examples will be presented separated in two different approaches i.e.: (i) perovskite oxides with enhanced physical properties by combining physical and chemical methods, such as epitaxial nanostructured BiFeO3, BaTiO3 or La0.7Sr0.3MnO3 thin films on silicon [1-3], and (ii) oxide nanomaterials entirely performed by soft chemistry and scalable top down lithographic techniques, such as nanostructured piezoelectric quartz thin films on silicon [4] or novel 1D-ferroelectric complex oxide epitaxially grown on silicon for vibration energy harvesting. The methodologies presented here exhibit a great potential and offers a pathway to design novel oxide compounds on silicon substrates by chemical routes with unique optical, electric, or magnetic properties. All these works have received funding from the European Research Council (ERC) and EU-H2020 research and innovation program under grants agreements No 803004 (SENSiSOFT) and No 654360 having benefitted from the framework of the NFFA-Europe that will be shortly presented after this talk. [1] Epitaxial La0.7Sr0.3MnO3 thin films on silicon with excellent magnetic and electric properties by combining physical and chemical methods. J. Vila-Fungueiriño et al. Science and Technology of Advanced Materials, Volume 19, (2018) [2] Electric and Mechanical Switching of Ferroelectric and Resistive States in Semiconducting BaTiO3–δ Films on Silicon. A. Gómez, J. et al. Small, 1701614 (2017) [3] Integration of functional complex oxide nanomaterials on silicon. J. Vila-Fungueiriño et al. Frontiers in Physics 3, 38 (2015) [4] Soft chemistry based routes to epitaxial α-quartz thin films on silicon with tunable textures. A.Carretero-Genevrier et al. Science. Vol 340. Pp 827-831 (2013)

O.8.1
09:00
Authors : I. Fina, F. Liu, F. Sanchez, J. Fontcuberta
Affiliations : Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193, Barcelona, Spain

Resume : Optoelectronic devices are mainly based on different semiconducting materials, which combination generates the presence of internal electric fields that can be used to drive carriers generated by light. Thus optical stimuli results in a change of the device electric properties. In ferroelectric materials, ferroelectric parameters such as polarization and coercive electric field are known to be modified under appropriate illumination. However, these changes do not present any advantage in front of the semiconducting based optoelectronic devices. However, if one could control the ferroelectric parameters by light in a non-volatile manner, the resulting device would present the advantage of having memory. In our contribution, we will demonstrate that by the control of surface adsorbates related to water in BaTiO3 films, we can switch on and off a particular ferroelectric property [1]. In this realization, we obtain a non-volatile modification of the measured switchable ferroelectric polarization under illumination, which persists when illumination is suppressed. X-ray photoelectron spectroscopy (XPS) experiments performed under visible light illumination have allowed to elucidate the origin of this phenomenon in the characterized BaTiO3 films, which will described in detail in our contribution. [1] F. Liu, I. Fina, G. Sauthier, F. Sanchez, A.M. Rappe, J. Fontcuberta, ACS Appl. Mater. Interfaces 10, 23968 (2018)

O.8.2
09:15
Authors : M. Gharbi1, F. Le Marrec1, C. Davoisne2, L. Dupont2, J. L. Dellis1, M.G. Karkut1, A. Sylvestre3 and N. Lemée1
Affiliations : 1 LPMC, EA 2081, University of Picardie Jules Verne, 80039 Amiens, France 2 LRCS, UMR CNRS 7314, University of Picardie Jules Verne, 80039 Amiens, France 3 University of Grenoble Alpes, CNRS, Grenoble INP, G2Elab, F-38000 Grenoble, France

Resume : The recent advances in the study of ferroelectric nanodomains has stimulated intense research in order to contribute to the fundamental knowledge of ferroelectric materials as well as for applications. Superlattice geometry provides a means to investigate domains at the nanoscale: by alternating individual ferroelectric layers with dielectric layers, it is possible (1) to produce ferroelectric domains which are isolated from surface or film-substrate interfaces, (2) to modify the electrostatic boundaries and mechanical strains., and (3) to tune the functional properties of the superlattices by adjusting the ferroelectric/ dielectric layer ratio. Here we present experimental results on a series of Pb(Zr0.2Ti0.8)O3 /SrTiO3 superlattices in which we evidence 180° stripe polar nanodomains. The structural and microstructural characteristics of these superlattices will be presented and the influence of the multidomain state on the ferroelectric phase transitions and the temperature dependant dielectric response will be reported.

O.8.3
09:30
Authors : N. Jedrecy1, C. Hebert1, V. Jagtap1, X. Portier2, A. Barbier3, J. Perriere1
Affiliations : 1 Institut des Nanosciences de Paris (INSP), Sorbonne Université, CNRS UMR 7588, 4 place Jussieu, 75252 Paris Cedex 05, France 2 Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP), CEA, CNRS UMR 6252, ENSICAEN, Normandie Université, 6 Boulevard Maréchal Juin, 14050 Caen, France 3 Service de Physique de l’Etat Condensé (SPEC), CEA, CNRS UMR 3680, Université Paris Saclay, Orme des Merisiers, CEA Saclay, 91191 Gif sur Yvette Cedex, France

Resume : Multiferroic materials, by combining ferromagnetism to ferroelectricity, are a promising playground for novel information storage devices. In particular, they could allow for the control of magnetization by an electric field or the control of electric polarization by a magnetic field. In this perspective, we have studied two-phase multiferroic heterostructures consisting of La0.7Sr0.3MnO3 (LSMO) and BaTiO3 (BTO) layers, with a thickness of about 50 nm, deposited by pulsed laser deposition (PLD). The LSMO and BTO layers may be grown epitaxial on MgO(001) with a cube-on-cube relationship. We made the Au/BTO/LSMO junction by means of lithography. Firstly, results will be presented, related to the crystalline atomic structure of the BTO/LSMO junction which was studied by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The atomic chemical composition was studied by Rutherford backscattering spectrometry (RBS) and electron microscopy derived techniques (EDX and EELS). Secondly, we will show that the LSMO layer provides ferromagnetic properties very close to the bulk ones, in particular a high value of the saturation magnetization (Ms about 150 kA.m-1 at 300 K), associated to a very small coercitive field (30 Oe at 300K), that means a possible low-field switch of the magnetization. In addition, the LSMO layer is metallic from 300 K up to 28 K. Finally, we will demonstrate the ferroelectric character of the junction, ensured by the BTO layer and checked through intensity-voltage (I-V) measurements by the use of top Au electrodes. A resistive switching behavior will be evidenced, explained on the basis of polarization switching. These results pave the way towards multiferroic tunnel junctions, with different resistive states according to the polarization state.

O.8.4
09:45
Authors : S. Basov 1,2,3, C. Elissalde 2, K. Temst 3, and L. Piraux 1
Affiliations : 1. BSMA-IMCN, Université catholique de Louvain, 1 Place Croix du Sud, Louvain-la-Neuve, Belgium, 1348 2. ICMCB-CNRS, Université de Bordeaux, 87 Avenue du Docteur Schweitzer, Pessac, France, 33600 3. Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium

Resume : Multiferroic materials show a coupling of ferroelectricity, ferromagnetism and ferroelastisity leading to a wide range of multifunctional devices, such as memories, sensors, and microwave devices. Materials with strong piezoelectric Pb0.52Zr0.48TiO3 (PZT), dielectric BaTiO3 (BTO) and magnetostrictive properties, CoFe2O4 (CFO), have been intensively studied in multilayered multiferroics. However, the strain in the multilayers is limited due to a substrate-imposed clamping resulting in small ME coupling. In this work, we have developed new strategies for the preparation of (1-3) multiferroic nanocomposites consisting of vertically aligned nanopillars (1) embedded in a matrix (3). Two kinds of materials were considered: i) CFO nanopillar arrays embedded in a BTO matrix, where an original in situ oxidation of magnetic CoFe2 nanopillars was used during rf magnetron sputtering of BTO; ii) CFO nanopillar arrays embedded in a PZT matrix, where in the first experiment, magnetic CoFe2 nanopillars were thermally oxidized, followed by the impregnation of the PZT using a sol-gel technique.1-3 The magnetoelectric coupling in the CFO nanopillar arrays embedded into BTO and PZT matrices can be interpreted by piezoelectricity and magnetostriction of the two phases, along with the reduced clamping, which enhances the strain interaction. [1] Sallagoity, et al., RCS Adv. 6, 106716 (2016) [2] Basov, et al., Nanotechnology 28, 475707 (2017) [3] Elissalde, et al., Ferroelectrics 532, 138 (2018)

O.8.5
10:00 Coffee break    
 
Ferroelectric oxides : -
10:30
Authors : Uwe Schroeder
Affiliations : Namlab gGmbH, Dresden, Germany

Resume : The ferroelectric (FE) behavior of thin doped hafnium oxide films or hafnium zirconium mixed oxide layers caused by a non-centrosymmetric orthorhombic phase was reported recently. Novel devices ranging from FE RAM (random access memory) and FE FET (field effect transistor) to ferroelectric tunnel junctions and negative capacitance devices using these dielectrics were proposed. For all devices a detailed understanding of the structural properties is necessary to improve the electrical performance of the material stack. Ferroelectric doped HfO2 films are typically processed by atomic layer deposition (ALD) or physical vapor deposition (PVD), but other deposition techniques like pulsed laser or molecular beam deposition are possible too. Depending on the deposition technique, process parameters like oxidant flow (e.g. PVD) or pulse time (ALD) during deposition can impact the ferroelectric properties of HfO2. In addition, the oxidant itself (H2O, O3, O2 plasma) determines oxygen, defect and contamination concentrations for ALD deposited films that can have an influence on the primary phase of HfO2. Furthermore, dopants, stress and grain size play a significant role in the phase formation process during crystallization. Overall, the impact of these process parameters on the ferroelectric devices performance is identified.

O.9.1
11:00
Authors : Mari Napari (1), Kham M. Niang (2), Rui Wu (1), Pavel Strichovaneč (3,) César Magén (3), Andrew J. Flewitt (2), Judith L. MacManus-Driscoll (1), José A. Pardo (3,4)
Affiliations : (1) Department of Materials Science and Metallurgy, University of Cambridge, UK; (2) Department of Engineering, University of Cambridge, UK; (3) Institute of Materials Science of Aragón, CSIC and University of Zaragoza, Spain; (4) Institute of Nanoscience of Aragón, University of Zaragoza, Spain

Resume : The experimental confirmation of ferroelectricity in thin films of the Hf1-xZrxO2 system has been clearly established (Appl. Phys. Lett. 110, 182905). However, a complete theoretical understanding of this behavior is still needed. The differences in the properties of films as a function of x for the same preparation conditions (Nano Lett. 12, 4318) invites exploration of the role played by cations ordering at the atomic level. In order to clarify this, we focus here on thin films with x=0.5 prepared by atomic layer deposition following different Hf/Zr sequences. 10-nm thick polycrystalline layers with overall Hf0.5Zr0.5O2 composition were deposited at 200ºC on TiN/SiO2/Si substrates using TDMAH and TDMAZ precursors. After deposition of TiN top electrodes the films were annealed in N2 atmosphere at moderate temperature which was high enough to induce the crystallization but low enough to prevent significant cation intermixing. The orthorhombic crystal structure was confirmed by X-ray diffraction. The film microstructure at the sub-nanometric level including Hf/Zr ordering was studied by transmission electron microscopy and electron energy loss spectroscopy. In the presentation we will show the correlation between the structure and ferroelectric properties of the films, as well as the influence of the cation disorder in this behavior. The conclusions enable a better understanding of the unusual ferroelectric properties of these simple binary oxides.

O.9.2
11:15
Authors : Jordan Bouaziz; Nicolas Baboux; Pedro Rojo Romeo; Lucian Pintilie; Raluca Negrea; Bertrand Vilquin
Affiliations : Jordan Bouaziz - Université de Lyon, Ecole Centrale de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 36 avenue Guy de Collongue, 69134 Ecully cedex, France - Université de Lyon, INSA de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 7 avenue Capelle, 69621 Villeurbanne cedex, France; Nicolas Baboux Université de Lyon, INSA de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 7 avenue Capelle, 69621 Villeurbanne cedex, France; Pedro Rojo Romeo Université de Lyon, Ecole Centrale de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 36 avenue Guy de Collongue, 69134 Ecully cedex, France; Lucian Pintilie National Institute of Materials Physics, Atomiștilor 405A, 077125 Măgurele, Ilfov, Romania; Raluca Negrea National Institute of Materials Physics, Atomiștilor 405A, 077125 Măgurele, Ilfov, Romania; Bertrand Vilquin Université de Lyon, Ecole Centrale de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 36 avenue Guy de Collongue, 69134 Ecully cedex, France;

Resume : Recently discovered, doped HfO2 [1] is a promising candidate for several ferroelectric applications. Among them, the most addressed are Negative-Capacitance Field Effect Transistor (NC-FET) and Ferroelectric Random Access Memory (FRAM). Compared to other materials, HfO2 processes have not only the advantage of being already integrated in Si CMOS industry, but also its ferroelectric properties are adequate for using oxide layer thinner than 10nm. Nevertheless, some of its properties should be improved for industrial applications. During cycling, the main issues are the limitation of the wake-up effect and the imprint, the fatigue and the endurance of the material. The ferroelectric phase (f-phase) has often been studied by Atomic Layer Deposition (ALD) [2]. However, most of the time the electrodes are made by Physical Vapor Deposition (PVD) processes, and industrial processes to separate Hf and Zr are usually expensive. It could be interesting to have only one process where the separation of Hf and Zr is not needed and where all depositions are made in the same machine. Furthermore, one of the most important benefit of sputtering is the deposition time which can be until 120 times faster than ALD depositions for the oxide layer. In this presentation, details will be given on how we succeeded in the deposition of ferroelectric hafnium/zirconium oxide (HZO) solid solutions by changing the pressure in the magnetron sputtering chamber in order to realize Metal/Insulator/Metal (MIM) capacitors. X-rays Diffraction (XRD), Transmission Electron Microscopy (TEM) and advanced electrical characterizations have been led to understand the difference between ferroelectric and non-ferroelectric samples. Two targets will be compared: a metallic Hf/Zr (56/44) target (reactive sputtering) and an oxide ZrO2/HfO2 (50/50) target (non-reactive sputtering). On these two targets, stoichiometry issues will be described and different fabrication tests have been led, such as: annealing at different temperatures, changing the size of the ferroelectric insulator layer, changing the size and the materials of the bottom and top electrodes, changing the oxygen flows, annealing with and without top electrodes. In each one of the studies, our understanding of the phenomena involved will be given. References: [1] T.S. Böscke, J. Müller, D. Bräuhaus, U. Schröder, U. Böttger, Ferroelectricity in hafnium oxide thin films, Appl. Phys. Lett. (2011). [2] M.H. Park, Y.H. Lee, H.J. Kim, Y.J. Kim, T. Moon, K. Do Kim, J. Müller, A. Kersch, U. Schroeder, T. Mikolajick, C.S. Hwang, Ferroelectricity and Antiferroelectricity of Doped Thin HfO2-Based Films, Adv. Mater. (2015)

O.9.3
11:30
Authors : M. C. Sulzbach, J. Lyu, X. Long, F. Sánchez, I. Fina, J. Fontcuberta
Affiliations : Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193, Catalonia, Spain

Resume : Hafnium oxide is pivotal in CMOS related applications and is being much investigated for data storage in resistive switching devices. The report of ferroelectricity in polycrystalline metal-doped hafnia samples opened new perspectives that have been further inflated by recent achievements showing that the ferroelectric phase can also be stabilized in epitaxial thin films. Here we report resistive switching observed in ultra thin ferroelectric films of Hf0.5Zr0.5O2. Films (about 4nm thick) grown by PLD on STO(001) substrates using (LaSr)MnO3 (LSMO) as bottom electrode. Two different type of metals (Pt and Co) have been used as top electrodes. We record the electroresistance (ER) by polarizing the junctions with different writing voltages. The junction resistance is measured through an current - writing voltage loop in small voltage range. Preliminary polarization loops have been recorded. It turns out that the device displays a remarkable polarization (about 15 uC/cm2) when measured at frequency 5 kHz with coercive voltage around 1.5 V. However when ER is measured in LSMO/HZO/Pt capacitors using a voltage-writing pulse of similar amplitude (≈2 V) and duration, no ER is observed. In contrast, a large ER (900%) is observed for larger writing pulses larger, around 4-5V. In LSMO/HZO/Co capacitors, ER is still not observed for writing amplitude close to the coercive voltage but only larger. We conclude that ER is governed by ionic-motion modulated junctions rather than polarization.

O.9.4
11:45
Authors : Xiaoyan Li 1, Vincent Garcia 2, Stéphane Fusil 2, Qiuxiang Zhu 2, Manuel Bibes 2, Agnès Barthélémy 2, Alexandre Gloter 1,
Affiliations : 1-Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud, 91405 Orsay France; 2-Unité Mixte de Physique CNRS Thales Université Paris-Saclay 91767 Palaiseau France;

Resume : The ferro-electric (FE) controlled “Mott transistor” shows great potential for non-volatile low power electronics. However, the achievement of the optimal field effect in the heterostructure is still challenging and its origin is not well understood, which hinder the practical device applications and development. [1-3] We investigate the field effect mechanism in a T-BiFeO3/(Ce,Ca)MnO3 (T-BFO/CCMO) bilayer Mott transistor using PFM ex-situ poling and Cs-corrected STEM and EELS spectro-microscopy. For a ferro-electric gate layer thicker than 10nm, an incomplete FE switch occurs. Only ca. 20% of BFO at the interfaces with the channel is successfully switched which is below the percolation threshold and explain the great deterioration of the resistance switch for theses devices. Such FE domain distribution result in the formation of tail-to-tail domain walls along (001) and {011} planes. The DW have widths of a typically 3-6 u.c. and present some structural disorder but no charge (Fe4 ) were evidence by EELS. Screening effect in the BFO imply a combination of defect, BFO surface charge and CCMO interface charge. Furthermore, when the switching is successful, a large modulation of ca. 2.4e- is found in the CCMO channel between the accumulation and depletion state, which is comparable to the values expected from an electrostatic value and confirm the potential of T-BFO gating to manipulate large amount of charge. [4] 1 Yamada H. et al. Scientific Reports 3, (2013). 2 Boyn S. et al. APL Materials 3, 061101 (2015) 3 Marinova M. et al. Nano Letters 15, 2533-2541, (2015). 4 Li X. et al. in preparation (2019).

O.9.5
12:00
Authors : C. Himcinschi *, J. Rix *, S. Brehm *, C. Röder *, J. Kortus *, K. Deepak §, W. Prellier §, I. Lindfors-Vrejoiu &, and M. Alexe #
Affiliations : * Institute of Theoretical Physics, TU Bergakademie Freiberg, 09596 Freiberg, Germany; § Laboratoire CRISMAT, CNRS-ENSICAEN,F-14050 Caen, France; & II. Physikalisches Institut, Universität zu Köln, D-50937, Germany; # Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom

Resume : The investigation of lattice vibrations in multiferroic BiFeO3 (BFO) crystals and thin films is of relevance for various practical applications due to their correlation to structural properties. However, the assignment of phonon symmetry is still controversial in the literature, due to the polar character of the oblique modes. Here we present symmetry assignment of the phonons obtained using azimuthal rotation dependent Raman measurements together with simulations based on Raman tensor formalism as well as taking into account mixed symmetries for the polar modes.[1] Raman spectroscopy can be used as a powerful tool for the investigation of ferroelastic domains in BFO exploiting the strong anisotropic intensity variation of some of the polar modes. Raman line scans and mappings were employed in order to identify ferroelastic domain patterns. Moreover, line scans performed with different excitation wavelengths and hence different penetration depths give information about the tilt of the domain walls with respect to the sample surface. Further, we will exemplify how Raman spectroscopy can be used as a tool to probe phase transitions such as orbital ordering in the case of 3d transition metal oxides. [2] The orbital ordering transition for LaVO3 and PrVO3 epitaxial films deposited on different substrates is addressed. [1] C. Himcinschi et al., Sci. Reports (2019) (in print, DOI: 10.1038/s41598-018-36462-5) [2] I. Vrejoiu, C. Himcinschi et al., APL Mater. 4, 046103 (2016).

O.9.6
12:30 Lunch    
 
Joint session with symposium Q : -
14:00
Authors : N Godard, A Mahjoub, S Girod, S Glinsek, E Defay*
Affiliations : Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 rue du Brill, L-4422 Belvaux, Luxembourg

Resume : Piezoelectric thin films for microsystems have recently met some noticeable industrial success such as AlN for acoustic RF filters and Pb(Zr,Ti)O¬3¬ (PZT) for inkjet print-heads actuators. In the case of perovskite oxides such as PZT, the sol gel technique has become the standard deposition means thanks to the high quality of the grown films on silicon. This approach gives nowadays the opportunity to think of deposition techniques that are more versatile such as inkjet printing (IJP). This leads to low cost and reliable fabrication techniques with which neither lithography nor etching are required anymore. Moreover, one can think of printing piezoelectric thin films on alternative substrates such as steel, glass or even polymers. At LIST, we study Chemical Solution Deposition (CSD) for functional oxides and more specifically for piezoelectric films. In this talk, I will present our latest advances regarding CSD and IJP deposition of piezoelectric films on silicon and glass substrates [Godard et al., Adv. Mat.Technol, 1800168 (2018)]. The key parameters of CSD and IJP will be discussed together with a comparison of the piezoelectric properties films on silicon and glass. Finally, two applications will be detailed, namely 1) an all-printed energy harvester and 2) fully transparent ultrasonic transducers, embedding transparent electrodes.

O.10.1
14:30
Authors : L. Pintilie, A. G. Boni, C. Chirila, L. Hrib
Affiliations : National Institute of Materials Physics, Atomistilor 405A, Magurele, 07715, Romania

Resume : Epitaxial PbZr0.2Ti0.8O3 capacitors were manufactured on single crystal SrTiO3 substrates with bottom and top SrRuO3 electrodes. Electrical measurements, namely polarization-voltage (P-V or hysteresis) and capacitance-voltage (C-V), were performed to evidence ferroelectricity. A modified C-V measurements was also developed to obtain the capacitance value in static conditions, with pre-set polarization state. The main conclusions of this study are: the experimental P-V and C-V characteristics are not in agreement with the theory predicting that the second is the derivative of the first one; the static C-V measurements reveal the fact that, after polarization switching and saturation, the capacitance value is practically constant, with negligible dependence on the applied voltage; the capacitance value calculated from static C-V at different thicknesses of the PZT layer extrapolates towards optical dielectric constant at thickness limit for stable ferroelectricity (about 1.2 nm); the derivative of P-V loop reveal the presence of a negative capacitance effect in the voltage range around coercive voltage, thus around zero value of polarization. It is suggested that, in almost perfect epitaxial PZT films, as it is the case for very thin films, the volume is completely depleted of free carriers, all being attracted to the electrode interfaces to compensate polarization charges. This may explain the low value of dielectric constant and the negative capacitance effect around P=0.

O.2.2
15:00
Authors : Urška Gabor, Nina Daneu, Zoran Samardžija, Danilo Suvorov and Matjaž Spreitzer
Affiliations : Advanced Materials Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Advanced Materials Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Department for Nanostructured Materials, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Advanced Materials Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; Advanced Materials Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia

Resume : Thin films of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) have been shown to exhibit attractive properties, which can be exploited for energy harvesting (EH), energy storage and electrocalorics. While most of the research and applications of thin-film piezoelectric EHs are based on the d31 mode, the d33 mode offers a higher potential figure of merit. We found that PMN-PT grown directly on SrTiO3 (STO) is extremely sensitive to the deposition conditions, easily leading to the nucleation of the undesired Pb-deficient pyrochlore phase. Contrarily, the window for growing phase-pure PMN-PT on STO, covered with a LaNiO3 bottom electrode, is considerably broader. In order to find the origin of the phase stabilization, we grew PMN-PT on other buffer layers such as SrO, SrRuO3 and PbZr0.52Ti0.48. The main reason for the enhanced stability of the perovskite phase was found to be the increased interface roughness, which enables stronger binding of Pb-based species. Thus, we modified the surface of the STO substrates by depositing a homoepitaxial layer prepared with a specifically designed process that ensures the growth of a stoichiometric and simultaneously rough STO layer. This led to a significantly improved phase purity of PMN-PT on STO, which represents an important step in the fabrication of EHs that operate in the d33 mode. Additionally, applying the same principle, other rough buffer layers can be designed to improve the integration of different Pb-based functional oxides on Si.

O.10.3
15:15
Authors : B. Aspe12, V. Demange13, X. Castel2, Q. Simon4, M. Zaghrioui4, K. Nadaud4, S. Députier1, F. Gouttefangeas3, R. Sauleau2, M. Guilloux-Viry13
Affiliations : 1 Univ. Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, France; 2 Univ. Rennes, CNRS, IETR – UMR 6164, F-35000 Rennes, France; 3 Univ. Rennes, CNRS, ScanMAT – UMS 2001, F-35000 Rennes, France; 4 Univ. Tours, CNRS, GREMAN – UMR 7347, F-37000 Tours, France;

Resume : The perovskite KxNa1-xNbO3 lead-free material is ever more investigated for its promising piezoelectric and ferroelectric properties. In the same K-Na-Nb-O (KNN) system, a tetragonal tungsten bronze (TTB) phase was reported but never fully investigated until now. This type of structure is known to exhibit piezoelectric properties in other systems such as Li-Na-Nb-O chemically close to KNN. However the synthesis and the identification of pure TTB phase are sensitive due to growth competition with numerous phases in these chemical systems. Therefore, the growth conditions using the pulsed laser deposition were optimized to obtain pure TTB KNN thin films. To identify the TTB phase with certitude, X-ray diffraction and electron transmission microscopy with electron diffraction techniques have been used. Raman spectroscopy as well as Energy Dispersion X-ray Spectroscopy and Scanning Electron Microscopy were also carried out to properly characterize the thin films. Pure TTB thin films have been deposited on (100) and (110) SrTiO3 substrates in order to investigate the oriented growth of the distinctive TTB nanorods. The low frequency (1 kHz - 1 MHz) dielectric characteristics (permittivity and loss tangent) have been retrieved from a thin film grown on (111)Pt/(001)Si substrate, whereas a thin film on C-cut sapphire substrate was used for measurements and characterizations at microwaves (1GHz - 40 GHz). A quite high dielectric permittivity value between 80 and 150 was measured.

O.10.4
15:30
Authors : Stefan Tappertzhofen, Simon Fichtner, Sebastian Bette, Thorsten Schmitz-Kempen, Bernhard Wagner, Norman Laske, Carl Van Buggenhout, Stephan Tiedke
Affiliations : aixACCT Systems GmbH, Aachen, Germany; Institute of Material Science, Christian-Albrechts-Universität, Kiel, Germany; Fraunhofer Institute for Silicon Technology, Itzehoe, Germany; Melexis Technologies NV, Tessenderlo, Belgium

Resume : Research on novel lead-free pyroelectric thin films is triggered by their promising integrability in CMOS processes and application in environmental friendly infra-red sensors. High precision characterization of such materials is a key challenge in development of new lead-free pyroelectric materials. In this study, we report on the characterization of pyroelectric thin films and piezo-composites, in particular analysis of the pyroelectric response and micro- and nanoscale thermal analysis, by using an advanced laser-based stimulation technique. We identified wide band gap semiconductor thin films fabricated by PVD and CSD processes, including Aluminum nitride and Scandium doped Aluminum nitride, as model materials for pyroelectric sensors due to their excellent dielectric properties and CMOS compatibility. By high frequency stimulation of a quantum cascade infrared-laser with selectable wavelength we measured through thickness polarization and thermal flux of exposed and integrated samples similar to the Laser Intensity Modulation Method. Parasitic piezoelectric contributions are accounted and modeled. These results are complemented by thermal simulation, and microscopic and spectroscopic techniques for fundamental thermal analysis down to the nanoscale. Our novel laser-based measurement system is an essential step forward for precise material characterization in research, and quality control on industrial scales for optimized device reliability.

O.10.5
15:45
Authors : A. Bembibre, A. Garitagoitia, Y. Lebsir, B. Sotillo, P. Fernández
Affiliations : Department of Materials Physics, Faculty of Physics, Complutense University of Madrid, Madrid, Spain.

Resume : The study of II-VI semiconductor has attracted much attention due to their potential applications in several fields. They are excellent candidates for optoelectronic devices due to their large direct band gap, chemical stability and large exciton binding energy. Among the II-VI semiconductors, ZnO is the most studied and applied in the fabrication of devices. The doping of ZnO with Yttrium has extended its use in gas sensors, solar cells or LEDs, as this dopant improves the optical and electrical properties of the zinc oxide. In this work, the material has been studied in two cases. Y-doped ZnO ceramics have been sintered, using a mixture of ZnO or ZnS and Y2O3 as precursor. Besides, doped micro and nanostructures have been grown using a vapor-solid method, using ZnS and Y2O3 as precursor. In both cases, the starting Yttrium content ranges from 0.4 to 3.6 at.%. Different characterization techniques have been applied to understand the differences between the ceramics and nanostructures properties. The characterization of the Y-doped ZnO has been performed by scanning electron microscopy based techniques: emissive mode, cathodoluminescence (CL) and X-ray microanalysis. Also, micro-Raman and X-Ray Diffraction measurements have been made. Special attention has been focused on the influence of the dopant in the CL emission and in the morphology of the micro- and nanostructures grown. As a proof of concepts, the behaviour as a gas sensor of the treated material have been studied.

O.10.6
16:00 Coffee break    
 
Poster session : Valentin Craciun, Maryline Guilloux-Viry, Zoe Barber, Florencio Sánchez
16:30
Authors : Federica Rigoni, Alessandro Faccin, Pedram Ghamgosar, Arnaud Bemou, Lorena Ramirez, Alberto Vomiero, Nils Almqvist
Affiliations : Department of Engineering Sciences and Mathematics, Division of Material Science, Luleå University of Technology, Sweden

Resume : Due to biocompatibility, chemical stability, non-toxicity, abundance and simple manufacturing process, metal-oxides are attractive materials to fabricate nanostructured optoelectronic devices, like photodetectors or solar cells. Nanowire (NW) based solar cells have been demonstrated to possess advantages in terms of electrical and optical properties over traditional thin film devices. Nowadays, resolving functional properties with high spatial resolution is crucial for future generation energy harvesting systems made up of heterogeneous nanoscale features. Atomic force microscopy (AFM) is a characterization method which allows to obtain functional imaging of surfaces, beyond morphological information with a resolution in the range of the nm. Conductive-AFM (c-AFM) is a powerful technique to obtain nano-electrical characterization related to the morphology of the surface. In this work, hydrothermally grown NWs of n-type oxides (ZnO and TiO2) have been conformally covered by p-type oxides (Cu2O and Co3O4) by different deposition methods, like ALD, CVD and sputtering. We successfully obtained core-shell ZnO-Cu2O and TiO2-Co3O4 NWs, which exhibit good photodetection (with a fast response time <0.1 s) and photovoltaics performances (achieving VOC = 0.34 V, JSC = 50 μA/cm2 and FF = 45%, in the macroscopic J-V characteristic). C-AFM measurements in dark and under illumination allowed to obtain the local photo-electrical properties of the investigated oxide materials at the nanoscale.

O.P11.1
16:30
Authors : Po-Chun Chen (1), Wei-Chiang Huang (1), Jiashing Yu (2), Shao-Sian Li (3), Cheng-Ying Chen (4).
Affiliations : 1 Department of Materials and Mineral Resources Engineering, National Taipei University of Technology 2 Department of Chemical Engineering, National Taiwan University 3 Graduate Institute of Biomedical Optomechatronics, Taipei Medical University 4 Center for Condensed Matter Sciences, National Taiwan University

Resume : Recently, implantable bio-electronic devices have attracted considerable attention owing to their promising potentials in monitoring and regulating malfunctioned neural systems and internal organs. In operation, these devices require a bio-compatible interface to facilitate the electrical signal communication between inorganic Si-based circuits and neurons/cells in an aqueous environment. A critical parameter for a bio-electrode is its “charge storage capacity” (CSC). A larger CSC is desirable for electrode miniaturization and irreversible-reaction minimization. We develop a chemical bath for a conformal iridium oxide deposition with a thickness of ~15 nm on titania nanotubes with length of ~800 nm. In addition, we develop an anodization process which can control the spacing of titania nanotube array. These IrO2 nanotube arrays undergo electrochemical analysis in charge storage capacity (CSC) and electrochemical impedance to evaluate its potential as neurostimulating electrodes for bioelectronics. Images from electron microscopes confirm the formation of uniform IrO2 on both internal and external surface of nanotubes. An X-ray diffraction pattern indicates a good crystallinity of the IrO2 nanotube array. In addition, the cycling lifetime of IrO2 nanotube arrays is evaluated by performing CV scans for 1,000 cycles with a scan rate of 0.1 V/s. The IrO2 nanotube arrays reveal large CSC values and low electrochemical impedances which are attributed to hollow tubular nanostructure with IrO2 deposition. Additionally, the IrO2-coated titania nanotube array exhibits stability, durability, and good biocompatibility.

O.P11.2
16:30
Authors : P. John1, H. Rotella1, C. Deparis1, M. Leroux1, F. Georgi2, G. Monge2, J. Zúñiga-Pérez1
Affiliations : 1 CNRS-CRHEA, Rue Bernard Grégory, 06560 Valbonne, France; 2 CEMEF MINES ParisTech, 1 Rue Claude Daunesse, 06904 Sophia Antipolis, France;

Resume : Nowadays thin film transistors (TFTs) are widely applied in flat panel displays, including active-matrix liquid-crystal displays. In order to achieve a higher resolution it is required to increase the pixel density and, thus, the TFT density implemented in the panel. Under these circumstances, the commonly used a-Si:H TFTs need to be replaced by alternative materials with larger electron mobilities. In this context, we want to introduce a new ZnMgON-based material to improve the TFT’s performance. This alloy can be considered as a combination of the four binary compounds ZnO, MgO, Zn3N2 and Mg3N2. Due to the numerous physical differences between these binaries including crystal structure, lattice parameters and coordination numbers, the stabilization of this new material requires growth methods far from equilibrium, such as molecular beam epitaxy (MBE), and crystalline substrates of wisely-chosen symmetry imposing a certain crystal structure to the desired alloy. In this contribution we present the growth of the above-mentioned binary thin films and first ternary alloys by MBE as a first step to achieve ZnMgON layers. The structural and surface properties were analyzed by X-ray diffraction and atomic force microscopy, respectively while X-ray photoelectron spectroscopy has been used to qualify the film composition. Finally, preliminary results on optical characterization will be shown and compared with those of nanopowders commonly used in ceramic industry. ANR-17-CE24-0043-01

O.P11.3
16:30
Authors : M. H. M. Abdelrehman1*, V. Craciun2, R. E. Kroon1, A. Yousif1,3, H.A.A. Seed Ahmed1,3, H. C. Swart1*
Affiliations : 1Department of Physics, Box 339, University of the Free State, Bloemfontein 9300, South Africa 2Laser Department, National Institute for Laser, Plasma and Radiation Physics, Bucharest-Magurele, Romania 3Department of Physics, Box 321, University of Khartoum, Omdurman 11115, Sudan *Corresponding author e-mail address: hassanmma@ufs.ac.za, SwartHC@ufs.ac.za

Resume : The alkali-earth oxide phosphor SrO:Bi offers a potential low-cost alternative to lanthanide-based blue phosphors. It has been reported in the powder form due to its properties and applicability in several types of optoelectronic devices. Pulsed laser deposition (PLD) was used to grow thin films from a Sr1-xO:Bix=0.002 target prepared from powders optimized for blue luminescence and obtained by sol-gel combustion. Thin films were successfully fabricated by PLD in vacuum or an O2 working atmosphere on Si (100) substrates. Films were deposited at different substrate temperatures using a Nd:YAG laser (266 nm) with energy 33.3 mJ/pulse, a KrF laser (248 nm) with energy 300 mJ/pulse or an ArF laser (193 nm) with energy 150 mJ/pulse. The X-ray diffraction (XRD) of the films deposited using the Nd:YAG laser in O2 showed that the crystallinity increased with an increase in the substrate temperature, changing from amorphous to a cubic structure. All films deposited in vacuum were amorphous. The optimum substrate temperatures for the maximum luminescence (both photoluminescence (PL) and cathodoluminescence (CL)) were 200 °C and 50 °C for deposition in O2 and vacuum, respectively. The main PL emission peak position of the thin films showed a shift to shorter wavelengths at 427 nm, when compared to the powder (445 nm). The difference in wavelength was attributed to the Bi3+ ions, which are very sensitive towards the environment. XRD of the thin films obtained with the different types of excimer lasers showed the thin films also had a strong (111) preferential orientation on the cubic phase. PL spectra showed blue emissions at 425 nm with a small shift to shorter wavelength compared with the powder, which was attributed to Si diffusion in the films.

O.P11.4
16:30
Authors : V. Stancu 1, L. Trupina 1, L. Nedelcu 1, V. Mihalache 1, M. G. Banciu 1, L. Huitema 2, A. Ghalem 2, A. Crunteanu 2, C. Constatinescu 3, F. Dumas-Bouchiat 3, C. Champeaux 3
Affiliations : 1 National Institute of Materials Physics, Bucharest-Magurele, Romania, 2 XLIM UMR 7252 - CNRS / University of Limoges, Limoges, France, 3 IRCER UMR 7315 - CNRS / University of Limoges, Limoges, France

Resume : 0.92Bi0.5Na0.5TiO3 – 0.08BaTiO3 (BNT-BT) ferroelectric thin films have been grown on MgO(100) and Ir-coated MgO(100) substrates by using sol-gel method. The solution was prepared from bismuth acetate, sodium acetate anhydrous, titanium isopropoxide and barium acetate. An excess of 10 mol. % and 5 mol. % for the sodium and the bismuth, respectively, was used to compensate their evaporation during the crystallization treatment at 800 oC. Structural, and morphological characterization of the BNT-BT films were performed by X-ray Diffraction and Scanning Electron Microscopy. The dielectric properties were determined on out-of-plane metal-insulator-metal (MIM) and planar inter-digitated capacitors (IDC) microfabricated by photolithography. The characterization of the MIM and IDC structures was performed in the 100 MHz – 60 GHz frequency domain in reflection mode. The dielectric properties of BNT-BT thin films will be discussed with respect to their potential for integration in electrically controlled devices. Acknowledgements: This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CCCDI – UEFISCDI project number 61/2016 (MASTERS), within PNCDI III.

O.P11.5
16:30
Authors : A. Louiset, N. Cherkashin, S. Schamm-Chardon, O. Kononchuk
Affiliations : CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse, France and SOITEC, Parc des Fontaines, F-38560 Bernin, France; CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse, France; CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse, France; SOITEC, Parc des Fontaines, F-38560 Bernin, France

Resume : Lithium Tantalate (LiTaO3 or LTO) is a material with unique piezoelectric properties and high potential for application in Surface Acoustic Wave (SAW) filters. The combination of thin LTO layers with Si/SiO2 substrates allows the increase of SAW Q factors as well as the decrease of frequency temperature coefficient. One promising option to manufacture such structures is to transfer the LTO layer by using the Smart CutTM technology, which is based on Hydrogen ion implantation and annealing. How such a polar material reacts to H implantation is expected to be very complex. Also, the way its piezoelectric and structural properties are affected is not known. We studied the effect of H ions fluence (from 1e16 to 9e16 H /cm2) on strain generation within the implanted regions of initially single crystalline LTO (oriented off the piezoelectric axis [0001]). By combining high-resolution XRD measurements with elasticity theory we developed for this system, we extracted depth profiles of 3D full strain tensor components. Hydrogen depth profiles measured by SIMS and TEM cross-sectional imaging supported this investigation. We highlighted the appearance of strong shear strain in such modified regions and estimate strain-induced piezoelectric polarization distribution inside the layer. Finally, the relation between H concentration and strain will be discussed, as well as the impact of ion implantation on piezoelectric properties.

O.P11.6
16:30
Authors : Tomas Murauskas, Valentina Plaušinaitienė
Affiliations : Vilnius University, Faculty of Chemistry and Geosciences

Resume : Cost-effective transparent conductive oxide (TCO) material composed of cheap and abundant elements is highly desired in today’s optoelectronics. Just recently wide-bandgap La-doped barium stannate (LBSO) semiconductor with outstanding electrical properties has been discovered. Synthesis of thin LBSO films is still challenging due to nonstoichiometry and various defects. Understanding of these factors is important for the control of the properties for application as transparent electrodes. Therefore, in this work Pulsed injection metalorganic chemical vapor deposition (PI-MOCVD) method was used for the growth of unmodified BaSnO3 (BSO) films. BSO films were deposited on LaAlO3, SrTiO3, sapphire substrates and film nonstoichiometry and defect issues were investigated. It was determined that a surplus amount of barium is required to obtain stoichiometric films. Also, slight deviation form stoichiometric ratio resulted in significant microstructure and optical properties changes whilst maintaining pure cubic phase. Increase of lattice parameter with the increase of Ba/Sn ratio in the films suggests a certain defect-forming mechanism possibly related to oxygen atom vacancies.

O.P11.7
16:30
Authors : Iu. Naseka 1, S. Mulenko 2, W. Paszkowicz 3, R. Savkina 1, and A. Smirnov 1
Affiliations : 1 V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 41 Nauky av, Kyiv 03028, Ukraine 2 G. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine, 36 Vernadsky Blvd, Kyiv 03142, Ukraine 3 Institute of Physics, Polish Academy of Science, al. Lotników 32/46, PL-02-668 Warsaw, Poland

Resume : Transition metal oxides are characterized by a wide variety of magnetic, optical and catalytic properties that are now used in numerous electronic applications. Isostructural and isovalent iron and chromium oxides are the subject of active experimental and theoretical investigations last time. Up to now, Cr2O3 has been most promising material for realistic applications close to room temperature in magnetoelectric-controlled spintronic elements like MERAM. An important property of hematite is its low-toxicity, Earth abundant and suitable redox potential for photocatalytic water dissociation. Combination of these materials in multilayer composite can allow to obtain new multifunctional structure and leads to improve of their magnetic or optical properties. In our work, nanometric iron and chromium oxide layers, their multilayer combinations and solid solutions were grown on silicon and glass substrates by the reactive pulsed laser deposition techniques at various technological parameters such as oxygen pressure in the reactor, substrate temperature, number of laser pulses. The structural, electrical and optical properties of these films were then studied. The methods of low-temperature photoluminescence and Raman spectroscopy techniques, were used for the investigation of the recombination and vibrational properties. Study of the charge carriers’ transport kinetics was carried out by surface photovoltage (SPV) and impedance spectroscopy technique. It is shown that oxides are present on the surface in different phases, and the technological parameters and composition of these films significantly affect their properties.

O.P11.8
16:30
Authors : Havva Eda Aysal (1,2), Doğancan Sarı (1,2), Fatih Pişkin (1,3), Tayfur Öztürk (1,2)
Affiliations : (1) Center for Energy Materials and Storage Devices, Middle East Technical University, 06800 Cankaya, Ankara (2) Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Cankaya, Ankara (3) Department of Metallurgical and Materials Engineering, Mugla Sıtkı Kocman University, 48000 Mugla

Resume : The composition and microstructure of cathode materials has a large impact on the performance of solid oxide fuel cells (SOFCs). It was recently shown [1] that the sputter deposited (La0.8Sr0.2) CoO3 (LSC-113) - (La0.5Sr0.5)2CoO4 (LSC-214) dual phase cathode yield the best performance where the mixture had an amorphous-like structure. In this study a composite cathodes LSC113-LSC214 and LSF-LSM were synthesized via thermal plasma using a large flow rate of quenching gas yielding fine non-equilibrium cathode powder. The purpose is to see if similar performance improvement could be obtained with plasma synthesized composite powders. The powders were screen printed onto suitable electrolytes and were characterized based on EIS responses using a symmetric cell. [1] Sarı D. et al., Combinatorial Development of nanocrystalline/amorphous (La,Sr)CoO3-(La,Sr)2CoO4 Composite Cathodes for IT-SOFCs, Solid State Ionics, 326, 124-130, 2018. [2] Torunoğlu Z. Ç. et al., One pot synthesis of (La,Sr)CoO3/(La,Sr)2CoO4 for IT-SOFCs cathodes, Int, J. of Hydrogen Energy, 43, 18642-18649, 2018.

O.P11.9
16:30
Authors : M. Kompitsas1, P. Koralli1, G. Mousdis1, G. Dorcioman2, D. Craciun2, S. Irimiciuc2, B. Hodoroaba3, P. Garoi2, and V. Craciun2, 4
Affiliations : 1National Hellenic Research, Foundation, Theor. and Phys./Chem. Institute, Athens, Greece 2National Institute for Lasers, Plasma and Radiation Physics, Măgurele, Romania 3Physics Faculty, University of Bucharest, Magurele, Romania 4Extreme Light Infrastructure-Nuclear Physics, Magurele, Romania

Resume : Thin iron oxide films were grown using the pulsed laser deposition (PLD) technique on quartz tubes at room temperature from a pure Fe target under various oxygen pressures. Two different laser sources (ArF, 193 nm and KrF, 248 nm wavelengths) were used. The structure of thin films were investigated using X-ray reflectivity and grazing incidence X-ray diffraction, while the chemical composition was investigated using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface morphology was investigated using scanning electron microscopy. The deposited films were tested as chemo-electrical sensors in a home-made setup, against hexane and octane compounds, at various operating temperatures and vapor concentrations in air. The sensing properties of the iron oxide films were correlated with their growth parameters, and their structure, surface morphology and chemical composition.

O.P11.10
16:30
Authors : B. Wagué1, J-B. Brubach2, G. Niu3, G. Dong3, L. Dai3, P. Roy2, G. Saint-Girons1, P. Rojo-Romeo1, Y. Robach1, B. Vilquin1
Affiliations : 1 Universite de Lyon, Ecole Centrale de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 36 avenue Guy de Collongue, 69134 Ecully Cedex, France 2 Synchrotron SOLEIL, ligne AILES, L’orme des merisiers, 91190 Saint Aubin, France 3 Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, China.

Resume : BaTiO3 thin films (60 nm-thick) grown on SrTiO3/Si templates have been characterized for their structural and electrical properties. The epitaxy of the BTO film on silicon was confirmed by X-ray diffraction with a good crystallinity. The temperature-dependance structural properties were checked by infrared spectroscopy in the absorption mode. The films were found to remain in a single ferroelectric phase over a temperature range from 5 to 385 K. Low-temperature orthorhombic-rhombohedral phase transitions characteristic of bulk BaTiO3 are absent in the films due to the clamping effect from the Si substrate. The electrical characterizations of the BaTiO3 films using MFIS structures show that samples shows a memory window with hysteresis loops which thus enable BaTiO3 possibly being applied to the non-volatile memory application.

O.P11.11
16:30
Authors : B. Wague1, M. Apreutesei1, J. Bouaziz1, N. Baboux2, P. Rojo Romeo1, B. Vilquin1
Affiliations : 1 Université de Lyon, Ecole Centrale de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 36 avenue Guy de Collongue, 69134 ECULLY Cedex, FRANCE 2 Université de Lyon, INSA de Lyon, Institut des Nanotechnologies de Lyon, CNRS UMR5270, 7 avenue Capelle, 69621 VILLEURBANNE Cedex, France

Resume : The properties of BaTiO3 (BTO) thin films deposited on different substrates by RF magnetron sputtering were investigated. Two representative substrates were selected and different heterostructures were studied. (i) SrTiO3 (STO) single crystals as a bulk oxide reference material, and (ii) silicon as a semiconductor. SrRuO3 (SRO) and Pt bottom electrodes were deposited on the silicon substrate. The BTO structural characterizations show that the films have (001) crystallographic orientation. We have compared the electrical properties of the different BTO layers and the same dielectric constant and polarization values were obtained whatever the substrate.

O.P11.12
16:30
Authors : Preetam Kumar Sharma1*, Yisong Han1, Ashlene Vennard2, Patrick Lemoine1, Maureen Strawhorne2, J. Anthony Byrne1
Affiliations : 1NIBEC, Ulster University, Shore Road, Newtownabbey, BT37 0QB, UK; 2AVX Ltd, 5, Hillman's Way, Coleraine, BT52 2DA, UK

Resume : Multilayer ceramic capacitors (MLCC) are one of the dominant passive components in electronic devices. Historically, MLCCs were fabricated using precious metal electrodes; however, to reduce costs cheaper base-metal electrode (BME) devices using Ni and Cu have been developed. BME MLCCs are typically fabricated using a tape casting process, building up multilayers of dielectric interspaced with screen printed Ni electrodes. The devices are subjected to a burnout and sintering process in a controlled reducing environment. In the next step, the devices were oxidised in a partially oxidising atmosphere to reduce the concentration of oxygen vacancies. The nature of the interface between the metal electrode and the dielect¬ric is of paramount importance for the device performance and reliability. Ni oxidation has been investigated in past using several methods including the measurement of oxygen partial pressure, O18 isotope investigation, scanning electron microscopy (SEM), transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDX), electron diffraction and secondary ion mass spectrometry (SIMS). It has been reported that oxygen diffuses much faster in the dielectric than the metal electrode and hence, the metal oxidation takes place at the metal-ceramic interfaces. In this investigation, Ni oxidation in BME MLCCs is being examined using different analytical techniques including X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, SEM, TEM, EDX, and TOF-SIMS.

O.P11.13
16:30
Authors : Alexis MARTIN, Xavier CASTEL, Mohamed HIMDI, Stéphanie DEPUTIER, Maryline GUILLOUX-VIRY
Affiliations : Université de Rennes, CNRS, IETR – UMR 6164, F-35000 Rennes, FRANCE; Université de Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, FRANCE

Resume : Nowadays the development of wireless communications requires emerging technologies to improve the network antenna performance, especially in dense urban areas. An attractive possibility concerns the development of optically transparent and reconfigurable antennas. The transparency aims at improving their location by accessing new surfaces, namely glazed surfaces. The frequency-agility aims at improving the number of covered standards through a single antenna. In this study we present a transparent and miniature frequency-agile antenna operating at 10 GHz and printed onto KTa0.5Nb0.5O3 (KTN) ferroelectric thin film deposited by PLD on R-plane sapphire. On one hand, optical transparency T of such antenna (T>80%) is achieved through high KTN and sapphire transparencies, and by using a transparent and conducting micrometric mesh silver layer. This exhibits a sheet resistance value as low as 0.24 ohm/sq, thereby lowering the ohmic loss. On other hand, frequency-agility is achieved by tuning the KTN dielectric permittivity Er under an external DC electric field, from 700 without biasing to 200 under 150 kV/cm at 10 GHz. Confined in the middle of the upper slot of the square-loop coplanar antenna, Er variation under biasing of the 420 nm-thick KTN film changes the antenna electrical length, and thereby its operating frequency from 10.6 GHz (without biasing) to 10.8 GHz (150 kV/cm). Experimental results will be compared with those from numerical simulations and an opaque counterpart.

O.P11.14
16:30
Authors : Hyun Kyu Jung, Tae Cheol Kim, Seung Han Lee, Dong Hun Kim
Affiliations : Department of Materials Science and Engineering, Myongji University, Yongin, Republic of Korea

Resume : Functional oxides are attractive for next generation electronic materials due to their versatile properties. Nanocomposite oxides with heterogeneous structures can allow combinations of useful properties in one film. A notable example is nanocomposites formed from spinel and perovskite which show both magnetism and ferroelectricity but it is possible to take advantage of more versatile functionalities if other functional elements can be contained in nanocomposites. In this work we show the formation of three components nanocomposite thin films formed by the deposition of films from a composite target by sputtering on (001) oriented SrTiO3, silicon substrate. Three component nanocomposites consisted of perovskite, spinel, and garnet phases, for example ferroelectric BiFeO3 (BFO)-ferrimagnetic CoFe2O4 (CFO)-ferrimagnetic Y3Fe5O12 (YIG) or BaTiO3 (BTO)-CFO-YIG. The microstructures and strain states of nanocomposites were characterized by high resolution X-ray diffraction (HRXRD) and transmittance electron microscopy (TEM). The ferroelectricity and ferromagnetism were measured by piezoresponse force microscopy (PFM) and vibrating sample magnetometer (VSM). The resulting three component films exhibited vertically aligned nanostructure consisted of a perovskite matrix containing vertical nanorods of CFO and nanoparticles of YIG. The magnetic behavior changed significantly compared to two component BFO-CFO or BTO-CFO nanocomposites. Magnetic hysteresis loops showed reversal of a soft and a hard magnetic component origiated from CFO and YIG phases.

O.P11.15
16:30
Authors : Hyun Kyu Jung, Tae Cheol Kim, Seung Han Lee, HanJin Lee, Dong Hun Kim
Affiliations : Department of Materials Science and Engineering, Myongji University, Yongin, Republic of Korea

Resume : Self-assembled nanocomposite thin films which ferromagnetic CoFe2O4 (CFO) nanopillars grow in a ferroelectric BiFeO3 (BFO) matrix have been tremendously attracted for next generation multiple state memory devices. When a ferroelectric BFO and a ferrimagnetic CFO are deposited at the same time using pulsed laser deposition and sputtering, self-assembled epitaxial nanocomposites were grown in which CFO pillars grew in BFO matrix along the same crystallographic direction. Both phases are in good lattice mismatch leading to an epitaxial growth along the vertical direction. The vertical strain at the interface plays an important role in manipulating the magnetic and ferroelectric properties because CFO is a magnetostrictive and BFO is a piezoelectric material. It has been reported that coercive field and magnetic anisotropy of the nanocomposite thin films are critically affected by strain states and aspect ratio of CFO pillars within a BFO matrix. Therefore, controlling the magnetic hysteresis of the nanocomposite thin films by adjusting the composition or geometry of the pillars is necessary to optimize its performance. Herein we showed the preparation of ceramic composite targets and fabrication of the self-assembled nanocomposites using radio frequency (RF) magnetron sputtering. Then we investigated a relation between the strain states and magnetic anisotropy at nanocomposites with variety of BFO:CFO ratios. Finally, we described the effects of pillar length modulation on the strain state and magnetic properties of BFO-CFO nanocomposites. Some samples were selectively etched to remove BFO phase which constrains strain of CFO pillars to confirm the strain effect on magnetic anisotropy.

O.P11.16
16:30
Authors : A.Kozlov, O.Dikaya, A.Goikhman, K.Maksimova
Affiliations : REC "Functional Nanomaterials", Immanuel Kant Baltic Federal University, 236001,Gaidara str. 6, Kaliningrad, Russia

Resume : Cobalt-based perovskites attract much attention by their unusual electronic, transport, and magnetic properties. The various spin states of cobalt ions responsible for these properties are determined by the competition between the vibrational energy of the lattice and the Hund exchange energy. Among all cobaltites, LaCoO3 (LCO) is an interesting system for studying the transition of the spin state and related phenomena. At the moment, many properties have been studied regarding thick (> 20 nm) LCO films, as well as the presence of stable ferromagnetic ordering at temperatures of ~ 80K [1], which makes it very actual to study the specific dependence of functional properties on the film thickness in range of 5-10MLs. LCO films has been grown using the method of pulsed laser deposition, which provides the possibility of producing ultrathin epitaxial films with a thickness of about 5-10 monolayers. In order to analyze the effect film stress upon growth, different types of substrates and sublayers (LaAlO3, DyScO3, Ir, SrTiO3, LSAT) were used. Further studies were focused as well on the analyzing the composition of the film, its thickness and degree of crystallinity, by means of EDS, XRR, XRD and LEED complimentary techniques. In addition to studies concerning the evaluation of film quality, studies of the magnetostructural properties have been carried out.

O.P11.17
16:30
Authors : Chia-Yuen Chou, Cheng-Yi Liu
Affiliations : National Central University

Resume : Silicon oxynitrides have been used as the dielectric layer in metal-insulator-metal (MIM) capacitor for many semiconductor devices. Typically, the silicon oxynitride thin films are deposited by PECVD. Dielectric constant of PECVD silicon oxynitride thin films ranges from 3 to 7.5, which is between the dielectric constant of silicon nitride and silicon oxide. However, people note that there are some residual impurities, such as, hydrogen, will bond with silicon (or nitrogen) atoms in PECVD silicon oxynitride thin films and those residual impurities would influence the capacitance. In this work, we deposited silicon oxynitride thin films by sputtering, which can avoid the residual impurities and improve the film quality. Metal-insulator-metal (MIM) capacitor structure was fabricated on glass substrate by magnetron sputtering. The sputtered silicon oxynitride thin films are sandwiched between two copper electrodes as the dielectric layer. Using this MIM structure, the dielectric constant of the sputtered silicon oxynitride thin film is measured to be around 30 at 1 kHz frequency. It is much higher than the reported dielectric constant of PECVD silicon oxynitride thin films. Varying the nitrogen gas flux during sputtering process, the ratio among O-Si-N, Si-O, and Si-N bonds can be manipulated in the sputtered silicon oxynitride thin films, which can be evaluated by XPS analyze. Then, we can observe the relation between the bond structure and the dielectric constant of the sputtered silicon oxynitride thin films. The preliminary results show that the percentage of the Si-N bonds is relatively high in the sputtered silicon oxynitride thin film, compared to other bonds, such as, Si-O, O-Si-N. The rich Si-N bonds in the sputtered silicon oxynitride thin films could be the main reason for the higher dielectric constant of the sputtered silicon oxynitride thin films. PL analysis is also used to clarify the structure effect on the dielectric constant of the sputtered silicon oxynitride thin films. Furthermore, the edge effect would be discussed in this talk, as the size of the top and bottom electrode is not the same.

O.P11.18
16:30
Authors : M. Chettab, Q. Simon, P. Laffez
Affiliations : GREMAN, UMR 7347 University of Tours – CNRS, Tours, France

Resume : Oxides with the general formula ABO3 present a large variety of structural and physical properties. When A cation is small (Goldschmidt tolerance factor t <0.75), the Ilmenite (IL) structure, with A and B in six fold coordination, can be favored instead of the usually observed perovskite structure. Compounds adopting the IL structure display various functional properties, such as weak ferromagnetism, high static dielectric permittivity or semiconducting behavior, finding applications in various fields including photo-catalysis and gas sensing. This work focuses on the preparation of NiTiO3-IL thin films by RF magnetron co-sputtering starting from metallic Ni and Ti targets followed by post-annealing. The aim of this study is to tune the morphological and structural features of the films by changing: 1) the substrate (silicon, Al2O3), 2) the sputtering parameters, and 3) the annealing conditions in air with temperatures ranging from 600 to 900°C. This versatile process allows to adjust the stoichiometry of the films by controlling for every deposition conditions the power ratio of sputtering targets. Chemical composition, morphological and optical properties are investigated by Energy Dispersive X-ray spectroscopy, Scanning Electron Microscopy and optical spectroscopy respectively. The structure is examined by X-Ray Diffraction and Raman spectroscopy. This work links together the processing conditions of NiTiO3-IL films and their structural, morphological and optical features.

O.P11.19
16:30
Authors : Silviu Vulpe a, Florin Nastase a*, Mircea Dragoman a, Adrian Dinescu a, Cosmin Romanitan a, Antoniu Moldovan b, Nicoleta Apostol c
Affiliations : a National Institute for Research and Development in Microtechnologies -IMT Bucharest, 077190 Bucharest, Romania b National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, 077125 Bucharest, Romania c National Institute for Materials Physics, Atomistilor str. 405 A, Bucharest-Magurele, Romania *Corresponding author: E-mail address: florin.nastase@imt.ro , Full postal address: National Institute for Research and Development in Microtechnologies - IMT Bucharest, 126A Erou Iancu Nicolae Street, 077190 Bucharest, Romania

Resume : The effects of annealing temperature and film thickness on the crystal structure and ferroelectric properties of Al:HfO2 films were investigated. Ferroelectric MIM capacitors based on aluminium (Al) doped hafnium oxide (HfO2) thin films grown on titanium nitride (TiN)/silicon substrates and Cr/Au top electrodes were fabricated. The structural properties of ferroelectric layers were determined by grazing incidence X-ray diffraction (GIXRD) that showed formation of the orthorhombic phase in Al:HfO2 thin films. Recording and investigating ferroelectric domains in Al:HfO2 thin films was done with Piezoresponse force microscopy (PFM) technique. The atomic force microscopy (AFM) analyses indicate a very low value of roughness average, for all grown thin films, less than 0,25 nm. Electrical characterization were assessed by polarization-voltage (P-V), capacitance-voltage (C-V), and current-voltage (I-V) measurments at room temperature. Relevant changes depending on the thickness and annealing temperature were observed. The post-deposition annealing can influence the film structure by densification and increasing the degree of crystallization.

O.P11.20
16:30
Authors : Florin Nastase a*, Silviu Vulpe a, Mircea Dragoman a, Adrian Dinescu a, Cosmin Romanitan a, Antoniu Moldovan b, Nicoleta Apostol c
Affiliations : a National Institute for Research and Development in Microtechnologies -IMT Bucharest, 077190 Bucharest, Romania b National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, 077125 Bucharest, Romania c National Institute for Materials Physics, Atomistilor str. 405 A, Bucharest-Magurele, Romania *Corresponding author: E-mail address: florin.nastase@imt.ro , Full postal address: National Institute for Research and Development in Microtechnologies - IMT Bucharest, 126A Erou Iancu Nicolae Street, 077190 Bucharest, Romania

Resume : In this study we investigate the obtaining of dopant-free hafnium oxide, with ferroelectric properties. Due to the polycrystalline nature of HfO2 films grown by ALD, very small thicknesses of up to ~ 10 nm, as well as mixed orientation and phase composition, by controlling the oxidant dose during the ALD process, it is possible to obtain the monoclinic phase suppression in the hafnium oxide thin films. This suppression of the monoclinic phase involves the development of the polar orthorhombic Pbc21 phase, and implicitly the occurrence of the ferroelectric properties in dopant-free hafnium oxide thin films. Atomic layer deposition method was employed to growth the hafnium oxide thin films with thicknesses below 10 nm. Grazing incidence X-ray diffraction (GIXRD) results showed formation of the orthorhombic phase in dopant-free hafnium oxide thin films, with Pbc21 symmetry. Ferroelectric and electrical properties of the hafnium oxide thin films were assessed by piezoresponse force microscopy (PFM) and I-V and C-V measurements. In conclusion, suppression of the monoclinic phase with the rearranging oxygen vacancies and thickness scaling, is favorable to boost orthorhombic phase and implicitly the ferroelectricity phenomenon in dopant-free hafnium oxide thin films.

O.P11.21
16:30
Authors : Jisoo Kim, Minho Im, Jung Hyun Sok, Kyoungwan Park
Affiliations : Department of Physics, University of Seoul, Seoul 02504, Korea

Resume : Although ZnO thin films exhibited good resistance-change nonvolatile memory characteristics in terms of switching speed, on-off resistance ratio, and data retention, it is unlikely for the memory device to exhibit stable resistive-switching due to the electrical resistive-switching stresses. In order to improve the resistive-switching properties of ZnO-based ReRAM, a ZnO/SiOx multilayer structure has been proposed; the thickness of SiOx layer should be 1~2 nm. In this experiment, thermal annealing effect on the nonvolatile memory characteristics of the ZnO/SiOx multilayers was investigated. Both ZnO and SiOx thin films were deposited using RF magnetron sputtering technique at room temperature. The ZnO/SiOx multilayers were then annealed with various temperature and time conditions under N2 gas atmosphere. The nonvolatile memory parameters were measured along the thermal annealing conditions. Reproducible resistive-switching operations with the on-off resistance ratio of >102 were obtained during ~200 cycles. In the presentation, the effect of thermal treatment on the nonvolatile memory characteristics will be discussed with the experimental results.

O.P11.22
16:30
Authors : M. Becker, C.J. Burkhardt, R. Kleiner and D. Koelle
Affiliations : NMI Natural and Medical Sciences Institute at the University of Tuebingen and Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+ ; NMI Natural and Medical Sciences Institute at the University of Tuebingen; Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+; Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+

Resume : Thin films of lead-free 0.5(Ba0.7Ca0.3TiO3) – 0.5[Ba(Zr0.2Ti0.8)O3] (BCZT) were grown by Pulsed Laser Deposition (PLD) on (001)-oriented niobium doped strontium titanate (Nb:STO) single crystals and on platinized silicon substrates. X-Ray Diffraction (XRD) showed highly oriented epitaxial growth (FWHM: 0.08°) of the films on Nb:STO, whereas the films on platinized silicon are polycrystalline with no preferred orientation. However, the use of a 10 nm Nb:STO Seed-Layer on top of the platinum metallization enabled the growth of (111)-textured BCZT thin films (FWHM: 4.2°). The microstructure of the epitaxial films was further investigated by Scanning Transmission Electron Microscopy (STEM) and the occurrence of Edge-type misfit-dislocations at the film-substrate interface was found. Impedance spectroscopy revealed a dielectric relaxation process in the epitaxial films, whereas no relaxation was observed in the polycrystalline films. This may be attributed to different domain wall motion in the films.

O.P11.23
16:30
Authors : D. Craciun1, A. M. Rostas2, S. Irimiciuc1, B. Hodoroaba3, G. Dorcioman1, P. Garoi1, A. C. Galca2, and V. Craciun1, 4
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Măgurele, Romania 2National Institute for Materials Physics, Magurele, Romania 3Physics Faculty, University of Bucharest, Magurele, Romania 4Extreme Light Infrastructure-Nuclear Physics, Magurele, Romania

Resume : HfO2 is an important material for microelectronic and optical coating applications due to its excellent dielectric properties. When doped, it could be used as a ferroelectric, in memristors or sensors devices. It is well known that HfO2 properties depend on its oxygen content. To optimize its properties one usually optimizes the oxygen pressure during synthesis. We deposited thin HfO2 films with a PLD installation that uses an ArF excimer laser on Si and quartz substrates under various oxygen pressures to optimize their electrical and optical properties. After deposition, the mass density, surface roughness, structure, optical and dielectric properties were investigated using X-ray reflectivity, grazing incidence X-ray diffraction, optical transmittance, spectroscopic ellipsometry, X-ray photoelectron spectroscopy and scanning electron microscopy. However, the electron paramagnetic resonance (EPR) investigations of HfO2 films turned to be the most sensitive technique to oxygen deposition conditions and hence their oxygen content. The defects created due to the presence of oxygen during deposition of the HfO2 film were characterized using EPR. This made it possible to show the dependency between the concentration of defects and the used oxygen concentration, which was regulated by its pressure, and show an exponential increase of the EPR signal (which is directly proportional to the defects in the thin film). Acknowledgements The work presented was funded by Nucleu –INFLPR program and ELI 17/2017 project.

O.P11.24
16:30
Authors : Parul Pandey,1, Yugandhar Bitla,2, Matthias Zschornak,1,3, Mao Wang,1,4, Chi Xu,1,4, Jörg Grenzer,1, Dirk-Carl Meyer,3, Yi-Ying Chin,5, Hong-Ji Lin,5, Chien-Te Chen,5, Sibylle Gemming,1,6, Manfred Helm,1,4, Ying-Hao Chu,2,7,8, and Shengqiang Zhou1,
Affiliations : 1 Helmholtz-Zentrum-Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, D-01328 Dresden, Germany 2 Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan 3 Institute of Experimental Physics, Technische Universität Bergakademie Freiberg, Freiberg, Germany 4 Technische Universität Dresden, 01062 Dresden, Germany 5 National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan 6 Institute of Physics, Technische Universität, Chemnitz, Germany 7 Institute of Physics, Academia Sinica, Taipei, Taiwan 8 Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan

Resume : Ion irradiation has emerged as a powerful tool for the efficient control of uniaxial lattice expansion to fine tune and modulate the otherwise inaccessible complex correlated phases in oxide thin-films. We report the fine tuning of the magnetic moment, ferromagnetic-paramagnetic and metal-insulator transition temperatures in the NiCo2O4 inverse-spinel oxide by creating oxygen deficiencies, employing high energy He-ion irradiation. Tailoring of oxygen vacancies and consequently a uniaxial lattice expansion in the out-of-plane direction drives the system toward the increase of the magnetic moment by two-times in magnitude. The magnetic moment increases with the He-ion irradiation fluence up to 2.5×10^16/cm^2. Our results are corroborated well by spin-polarized electronic structure calculations with density functional theory and X-ray absorption spectroscopic data, which show peak-height change and energy shift of Co-L2,3 and Ni-L2,3 edges driven by the oxygen vacancies. These results demonstrate a new pathway of tailoring oxygen vacancies via He-ion irradiation, useful for designing new functionalities in other complex oxide thin films.

O.P11.25
16:30
Authors : Sahar Boukchina1,2, Hanene AKROUT1, Dominique Berling3,4, Latifa Bousselmi 1
Affiliations : 1 Laboratory of Wastewaters and Environment, Center of Water Researches and Technologies (CERTE),Technopark of Borj Cédria PB 273, Soliman 8020, Tunisia 2 National Institute of Applied Sciences and Technology (INSAT) 3 Université de Haute Alsace, Institute of Materials Science of Mulhouse (IS2M) UMR 7361, F-68100 Mulhouse, France 4 Université de Strasbourg, France

Resume : The antibiotics have been considered as hazardous chemical substances able to modify the equilibrium of the environment due to their high consumption, resistance to biodegradation process and potential risk for humans. In this work, Ti/TiO2/PbO2 anodes consisting of a PbO2 coating growth on the TiO2 interlayer deposited on titanium substrates were prepared combining different deposition technics: electrochemical method using anodization (Anod), electrodeposition (EL), and sol gel spin coating (SG). Different kinds of anodes have been tested for the removal of ampicillin from water by anodic oxidation. The morphology and the electrocatalytic activity of the anodes were investigated respectively by Scanning electron microscopy and electrochemical impedance spectroscopy. The performance of the electrodes was evaluated through high performance liquid chromatography and chemical oxygen demand measurements. Best results were obtained for the Ti/ TiO2SG/ PbO2EL anode exhibiting 64% of COD removal after 5hours of treatment compared to 54% and 31% for Ti/TiO2SG/PbO2SG and Ti/TiO2Anod/PbO2El respectively. HPLC analyses confirm also that faster decrease of ampicillin amount is obtained with Ti/ TiO2SG/ PbO2EL. Thus, the anode prepared by mixing sol gel and electrodeposition is a promising electrode with the best ability for the degradation of ampicillin through anodic oxidation.

O.P11.26
16:30
Authors : Pranab Biswas, Ardak Ainabayev, David Caffrey, Brian Walls, Daragh Mullarkey, Karsten Fleischer, Igor V. Shvets
Affiliations : School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin 2, Ireland

Resume : In this study electrical transport in Ti-doped iron oxide films in the temperature range 10 to 473 K was investigated. Iron oxide films were deposited on glass substrates using spray pyrolysis method at a temperature of 450 °C. Here, Iron (III) acetyleacetonate and Titanium diisopropoxide bis (acetylacetonate) were used as the Fe and Ti precursor, respectively, whereas methanol was used as the solvent. The undoped sample were observed to be very resistive in nature, whereas the doped ones were found to be conductive linearly with doping percentage. The UV-Vis transmission spectra showed a transition around 560 nm corresponding to 2.2 eV optical bandgap. The film with 20 % Ti showed a resistance of around 15 kΩ at room temperature. Seebeck coefficient measurement revealed n-type conductivity of the films. Low temperature Hall measurements were carried out using 4-point probe van der Pauw method. The carrier concentration, Hall mobility, and the resistivity of the films were measured to be 3.97 × 1018 cm-3, 1.07 cm2/V•s, and 1.47 Ω-cm, respectively at room temperature. In order to investigate temperature dependent electrical transport, resistivity of the films were measured as a function of temperature separately from 300 to 473 K (above room temperature) and 20 to 300 K (below room temperature). The films showed a normal semiconductor-like inversely-proportional behaviour of the resistivity with increasing temperature.

O.P11.27
16:30
Authors : Leila Zouridi, George Kiriakidis, George Marnelos, Vassilios Binas
Affiliations : Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, 100 N. Plastira str., Vassilika Vouton, 71110 Heraklion, Crete, Greece and University of Crete, Department of Department of Material Science and Technology, 710 03 Heraklion, Crete, Greece, Heraklion, Crete, Greece; Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, 100 N. Plastira str., Vassilika Vouton, 71110 Heraklion, Crete, Greece and University of Crete, Department of Physics, 710 03 Heraklion, Crete, Greece; Department of Environmental Engineering, University of Western Macedonia, Bakola & Sialvera, Kozani, GR-50100, Greece; Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, 100 N. Plastira str., Vassilika Vouton, 71110 Heraklion, Crete, Greece and Crete Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete, 71003 Heraklion, Greece

Resume : Inkjet printing constitutes a cost-effective and energy-efficient deposition method for automated and accurate thin film fabrication and surface patterning, thus making it an advance technology that can be easily integrated into industrial production lines. In this current study the use of inkjet printing for the fabrication of the electrode films of a novel solid oxide fuel cell device, is presented. More specifically, results on the development and optimisation of oxide nanoparticle suspensions/inks and their performance on the fabrication of oxide electrode films by inkjet printing, are discussed, as well as results on the characterisation of the printed oxide electrode films. Study of the agglomeration of particles in the oxides suspension, as well as storage tests were conducted by dynamic light scattering. The thermal degradation and evaporation rate were measured by differential scanning calorimetry and thermogravimetric analysis. Rheological characteristics over temperature were studied by viscometry measurements, while the ink to substrate interactions were tested by contact angle measurements via the sessile drop method. Homogeneity, porosity and morphology of the printed oxide films were observed by optical microscopy and scanning electron microscopy. Printed film thickness was measured by profilometry. The structural and chemical composition of the printed oxides inks through various fabrication steps were confirmed by x-ray diffraction and infrared spectroscopy.

O.P11.28
16:30
Authors : A. Majchrowicz, A. Roguska, M. Lewandowska
Affiliations : A. Majchrowicz, M. Lewandowska - Faculty of Materials Science and Engineering, Warsaw University of Technology (WUT), Warsaw, Poland; A. Roguska - Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland

Resume : In this work, the self-organized mixed-oxide nanotubes (NTs) has been fabricated on commercially pure α-phase titanium, single β-phase Ti-24Nb-4Zr-8Sn (Ti2448) alloy and α+β-phase Ti-13Zr-13Nb (Ti1313) alloy. The nanotubular oxide layers were manufactured by means of the electrochemical anodization process which was performed in ethylene glycol-based electrolyte with fluoride ions at constant voltage of 20 V for 2 h. Morphology of the fabricated NTs was characterized by SEM/STEM. Characteristic dimensions describing NTs, such as diameter, wall thickness and height, were determined based on the obtained microscopic images. The chemical analysis was performed by EDS and XPS methods. Despite of applying the same process parameters in all cases, NTs obtained on three different substrates showed a different morphology (e.g. smooth or ribbed walls). The values of diameters and heights of the NTs were different as well. The results of the chemical analysis allowed to determine the stoichiometry of the obtained oxides, their percentage content and distribution in the layer, and to explain the effect of the chemical composition of the substrate on the formation process of nanotubular layers.

O.P11.29
16:30
Authors : Jong-Hwan Yoon
Affiliations : Department of Physics, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon, Gangwon-do 24341, South Korea

Resume : Recent flash memory devices continue to be demanded to be smaller in size and exhibit faster operating speeds and high data storage stability of more than 10 years. In general, these properties strongly depend on the thickness of the tunneling oxide layer of transistors. For the devices of small size with a fast operation speed, it is necessary to reduce the thickness of the tunneling layer, but the tunnel oxide layer thickness in memory devices can hardly be scaled below 8 nm because of the charge loss through the thin tunneling layer. One approach to realize devices with high data storage stability that operate at high speed is to replace the single SiO2 tunnel oxide layer by a low-k/high-k tunnel dielectric stacked layer. Here, we report a simple method for fabricating Sn@Al2O3 core-shell nanoparticle (NP) layer embedded in SiO2, which has the effect of a metallic NP floating gate with a low-k (SiO2)/high-k (Al2O3) dielectric stacked tunneling layer. The core-shell NPs were simply formed by thermally annealing a layered structure consisting of an ultrathin Sn layer between two thin Al layers, where the layered structure of Al/Sn/Al was sandwiched between two thin silicon-rich oxide layers within SiO2. The floating gate with Sn@Al2O3 core-shell NPs was found to have much highly stable charge retention.

O.P11.30
16:30
Authors : Raju Mula1, Meher Wan2, Chacko Jacob*1
Affiliations : 1-Materials Science Centre, Indian Institute of Technology, Kharagpur, West Bengal, India- 721302 2-Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur, West Bengal, India- 721302

Resume : Low resistance large area two dimensional molybdenum dioxide (MoO2) thin crystals were grown on SiO2/Si substrates by chemical vapour deposition (CVD) method. The MoO2 crystals were synthesized by direct evaporation of MoO3 and also sublimation of MoO3 in presence of sulfur precursor inside CVD reactor at a higher temperature in presence of an Ar atmosphere, respectively. The grown crystals were large in size (up to 20µm in length) with a rhomboidal shape and also highly crystalline in nature with a height of few nanometers. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and atomic force microscopy were used to study the as grown MoO2 crystals. The electronic properties of MoO2 crystals were studied by fabricating devices using an individual crystal, with Pt serving as contacts from the two opposite sides of the MoO2 crystal. The thin crystals exhibited a comparatively high electrical conductivity. Keywords: Molybdenum dioxide (MoO2), Chemical vapour deposition (CVD), Electrical conductivity

O.P11.31
16:30
Authors : F. Andrei1, N. Enea1, I. Boerasu1, R. Birjega1, M. Dinescu1, A. Palla-Papavlu1, V. Ion1, N.D. Scarisoreanu1, V. Leca2
Affiliations : 1 National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania 2 Extreme Light Infrastructure - Nuclear Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, Magurele, Romania

Resume : In the last years, the global warming represents one of the biggest problem for our environment and it needs to be urgently solved. Photocatalysis using perovskite materials is considered to be the key of solving energy problemes, because this reaction type can use sunlight that is a clean and renewable energy source. Lanthanum ferrite (LaFeO3-LFO) and bismuth ferrite (BiFeO3-BFO) are possible candidates as photocatalysts due to high light absorption properties. In this work, we report the functional photoelectrochemical properties of different heterostructures BFO/LFO and LFO/BFO thin films obtained by pulsed laser deposition (PLD). The purpose of this survey was to combine the strong ferroelectricity and high chemical stability of BFO with the great absorption properties of LFO, generating in this way new photocatalysts with enhanced activities in photocatalytic reactions. Moreover, the influence on the water splitting reaction of the oxygen content and the induced strain defects in the perovskite structure was studied. X-Ray diffraction and high resolution electron microscopy (HR-TEM) techniques were used to study the structural properties of the obtained thin films, while the topography was analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The absorption properties were obtained by spectroscopic ellipsometry (SE), the band gap value being calculated using Tauc plots.

O.P11.32
16:30
Authors : Mohamed M Saad (1), Ahmed I Osman (2)
Affiliations : (1) School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK; (2) School of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast, BT9 5AG, UK

Resume : Smart nano-multifunctional complex oxide heterostructures such as metal insulating transition (MIT) thin films grown on different substrates and free-standing nanowires have recently received a renewed attention due to their promising novel nanotechnological applications and breakthrough in switching, sensing, energy-efficient smart windows and nonvolatile read access memories. There are several factors, which make this review particularly timely and important. Firstly, there is a market pressure, primarily from the nanoelectronic industry and energy sectors to develop highly efficient novel multifunctional optoelectronic nano-devices at low cost through process optimisation and band gap engineering. Secondly, there is an opportunity for novel exploration, new functionality and breakthrough at interfaces of these thermoelectric materials due to the recent developments in thin film growth and nanofabrication technology. Thirdly, there is a need to fully understand the intrinsic size effects on MIT performance at nanoscale in the absence of extrinsic factors. This feature review attempts to discuss thin film deposition and nanofabrication technological techniques of multifunctional complex oxide nanostructures including vanadium dioxide (VO2) MIT thin films on different substrates and free-standing nanowires. In particular, the evolution of thin film deposition and free-standing nanowires fabrication techniques using pulsed laser deposition (PLD), chemical vapour deposition (CVD), plasma enhanced chemical vapour deposition (PECVD), focused ion beam (FIB), thermal evaporation and sputtering systems are technically and critically reviewed.

O.P11.33
16:30
Authors : Md Ashraf Hossain, Sanghyun Jeon, Junhyuk Ahn, Junsung Bang, Hyungmok Joh, and Soong Ju Oh
Affiliations : Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea

Resume : Strain gauges are electromechanical sensors that measure the mechanical distortion of any objects. Recently, different types of strain gauges have been applied to a variety of devices such as wearable electronics, electronics skin, health care system, etc. Among different strain sensors, the resistive type strain sensor is the simplest form and has attracted huge attention due to low cost and high performance. Resistive type strain sensors function by reading the resistance change upon an application of external strain to objects. Recently colloidal nanocrystals (NCs) have been considered as new promising materials for strain sensor owing to their unique properties. In this study, we introduce a strategy to introduce solution-processed interfacial layers in nanocrystal (NC) thin films to fabricate high-performance strain sensors. SiO2 interfacial layers are chemically introduced in ligand-exchanged Ag NC thin films to increase the tunneling gap or inter-particle distance between each Ag NC. In this way, the charge-transport mechanism is manipulated, leading to unique electromechanical properties with a high gauge factor. All solution-processed strain gauge sensors with high stability, durability, and sensitivity are fabricated. The sensor successfully measured delicate movements such as finger motions, demonstrating its possible application in electronic skin.

O.P11.34
16:30
Authors : V. Bouquet (1), F. Baudouin (1), V. Demange (1), S. Députier (1), S. Ollivier (1), A. Fouchet (2), M. Guilloux-Viry (1)
Affiliations : (1) Univ Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, FRANCE (2) CRISMAT, CNRS UMR6508, ENSICAEN, Normandie Université, 14050 Caen Cedex 4, FRANCE

Resume : Integration of high quality complex oxides thin films, such as the multiferroic BiFeO3 (BFO) material, is required for the oxide electronics development. However, due to properties related to the crystalline orientation, optimal performances are mainly obtained on expensive single crystalline substrates. A lower cost alternative route would be the use of oxide nanosheet seed layers being able to be deposited on all types of substrates, in particular silicon (Si), which would allow to obtain complex oxides with desired crystallographic orientation and their integration in CMOS technology. In this work, BFO films were deposited by Chemical Solution Deposition (CSD) based on polymeric precursor method. First, the optimization of synthesis parameters were performed on amorphous silica and transposed on (100) Si substrates. The structural and microstructural characterizations have revealed a polycrystalline growth on both substrates and the strong influence of the synthesis temperature, in particular to obtain the pure perovskite phase. The influence of a two-dimensional nanosheet seed layer (2D-NS) was then investigated. From exfoliation of the lamellar niobate KCa2Nb3O10 prepared by solid state reaction, Ca2Nb3O10- nanosheets layer was deposited directly on Si substrates by Langmuir Blodgett process, followed by the subsequent deposition of BFO by CSD. X-ray diffraction measurements have evidenced (100) oriented BFO thin films confirming the great interest of 2D-NS seed layers.

O.P11.35
16:30
Authors : Minho Im, Jisoo Kim, Junghyun Sok, Kyoungwan Park
Affiliations : Department of Physics, University of Seoul, Seoul 02504, Korea

Resume : ZnO thin films have been widely investigated for ReRAM(Resistive Random Access Memory) applications, and the nonvolatile memory properties, such as fast switching speed, large on/off-resistance ratio, moderate endurance, and long retention, were revealed. Here, we consider using Zinc Silicate (ZnSiO3 or Zn2SiO4) as a new material for ReRAM application in order to improve various nonvolatile memory characteristics. Zinc Silicate thin films were deposited on a highly doped Si substrate by RF-magnetron sputtering method. We observed that the new Zinc Silicate thin films occasionally exhibited bipolar or unipolar resistive switching properties. In the bipolar operation, the set- and reset- voltages were around 3.5 V and -2.8 V, respectively. Current ratio of Low Resistance State (LRS)/High Resistance State (HRS) was 10². In the case of unipolar operation, the set- and reset- voltages were around 3.8 V and 1.2 V, and current ratio of LRS/HRS was ~10⁴. It should be noted that the unipolar operation showed not only larger resistance on/off ratio and lower reset voltage but also better endurance behavior than those of bipolar operation. However, the HRS of unipolar operation was unstable in endurance measurements. We speculated that the large current-fluctuations in HRS of the unipolar operation could be attributed to non-repeatable formation of the nonstoichiometric phase of Zinc Silicate. These results point to the possibility of using a Zinc Silicate thin film for ReRAM devices. Further experiments are necessary to understand its resistive switching mechanism and improve the nonvolatile memory properties.

O.P11.36
16:30
Authors : J. E. N. Swallow[1], J. B. Varley[2], L. A. H. Jones[1], J. T. Gibbon[1], L. F. J. Piper[3], V. R. Dhanak[1] and T. D. Veal[1]
Affiliations : [1] Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 7ZF, United Kingdom [2] Lawrence Livermore National Laboratory, Livermore, California 94550, USA [3] Department of Materials Science and Engineering, Binghamton University, Binghamton, New York 13902, USA

Resume : β-Ga2O3 is a transparent semiconductor material that has attracted a lot of interest in recent years due in part to its large band gap (~4.7 eV at room temperature) giving rise to its good transparency and high breakdown field (8 MVcm-1). These properties make β-Ga2O3 attractive for a whole host of applications, such as high power electronics, solar-blind UV detectors, and gas sensors. Whilst β-Ga2O3 is a very promising material, many of its fundamental properties have yet to be fully explored. One question relates to the surface electronic properties of this material. A few recent reports claim that β-Ga2O3 displays electron depletion at the surface, but with insufficient evidence and incorrect data analysis this question still remains. Here we use a combination of x-ray photoemission spectroscopy with high-quality single crystalline (2 ̅01) β-Ga2O3 and state-of-the-art density functional theory in order to determine the surface electronic properties of β-Ga2O3. Contrary to previous reports, we observe downward band bending (electron accumulation) at β-Ga2O3 surfaces when atmospheric contaminants are present, a phenomenon never before investigated for this material. In-situ cleaning shows a transition to upward band-bending. Finally, we investigate the effect of hydrogen at the surface and in the bulk of β-Ga2O3, showing its responsibility for the band bending transition observed.

O.P11.37
16:30
Authors : Özge Saglam
Affiliations : Faculty of Engineering, Izmir University of Economics, Izmir, Turkey.

Resume : The materials that perform upconversion are often used in optoelectronic devices, solar cells, safety inks, three-dimensional imaging devices, biological and medical applications due to energy conversion. 2D oxide nanosheets, a member of the 2D family of materials, are obtained by a chemical exfoliation of layered oxide bulk materials. The thickness of the 2D oxide nanosheets varies from one nm to several nanometers depending on the chemical composition of the host part of the layered material. In this study, the Ruddlesden-Popper type K2Ln2Ti3O10 (Ln: lanthanide) layered perovskite doped with Yb3 /Er3 , Yb3 /Tm3 , and Tm3 /Er3 ions were exfoliated to produce single Ln2Ti3O10 nanosheets. These nanosheets that have upconversion properties were used to fabricate nanofilms by the layer-by-layer method. The nanofilms having ~50 nm thickness assembled by joining a combination of these nanosheets have exhibited emission in different parts of the visible region by upconversion depending on the amount of doping with lanthanides, the annealing temperature of the layered materials, the order of the nanosheets during the nanofilm fabrication and thickness of the nanofilms. The characterization of the nanosheets and nanofilms were performed using Atomic Force Microscopy, X-ray Diffraction Spectroscopy, Scanning Electron Microscopy-EDX, Inductively Coupled Plasma and UV/VIS/NIR Spectroscopy techniques.

O.P11.38
16:30
Authors : Gesara Bimashofer, Jochen Stahn
Affiliations : Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland

Resume : Manganese based perovskites (“maganites”) of the composition A1-xBxMnO3 appear in various electronic and magnetic phases, with features like colossal magnetoresistance. Those phases are composition and temperature dependent as shown in complex phase diagrams. The complexity of this system originates from competition between order mechanisms, magnetic interactions and structural aspects. The macroscopic phase diagram is believed to be an overlap of small phases where the disorder that is induced by the distribution of A3+ and B2+ and the ratio of Mn3+/Mn4+ results in local variation of the mechanisms mentioned earlier. During this project, we want to cross magnetic phase boundaries reversibly by chemical doping and monitor the process in-situ. To achieve this, we want to use electrochemical lithium intercalation and de-intercalation. The material of choice is La1-xSrxMnO3 (LSMO) where lithium would replace part of lanthanum or strontium. At a composition of 50% strontium and at room temperature LSMO shows a phase transition between ferro- and paramagnetism. It is believed that one could switch between those magnetic states by lithium inter- and de-intercalation. Furthermore, the in-situ measurements are carried out using polarized neutron reflectometry (PNR) and the Van der Pauw method. With PNR, we investigate the distribution of the Lithium and the magnetic induction profile. With Van der Pauw we measure the change of conductivity and li-ion transport. Another goal is to relate these phenomena to the Mn3+/Mn4+ ratio. Because the process should be reversible we want to investigate the same sample in various states along the phase transition border using various methods and connect the different appearing phenomena as mentioned above to each other.

O.P11.39
16:30
Authors : Y. Kikuchi, 1, 2, Q. Simon, 1, A. Yamamoto, 2, P. Laffez, 1
Affiliations : 1) GREMAN, UMR 7347 University of Tours – CNRS, Tours, France ; 2) Shibaura Institute of Technology, Tokyo, Japan

Resume : Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC) are electrochemical energy converters using renewable fuel such as hydrogen. Their performances are strongly related to the catalytic/conductive properties of cathode materials, which are temperature dependent. For practical application, the optimal operating conditions imply a tradeoff between high efficiency at high temperatures and improved lifetime at intermediate temperatures (below 1000°C). Among the candidates, Pr2NiO4 has good functional properties but is susceptible to decompose to Pr4Ni3O10 under IT-SOFC conditions. In this contribution, the Pr4Ni3O10 phase has been directly targeted as a potential alternative to Pr2NiO4. Pr4Ni3O10 thin films have been deposited on Y-stabilized Zirconia substrates through a twostep process: i) room temperature co-sputtering of metallic Ni and Pr targets, ii) ex-situ annealing under oxygen flux. The composition of thin films were adjusted by changing the power applied to each targets and controlled by Energy Dispersive Spectroscopy. The optimal annealing conditions were identified by X-Ray Diffraction analyses as a function of temperature up to 1200°C. These analyses revealed that the system showed the evolution from single metal oxides to Pr4Ni3O10 phase above 1000°C, which finally transformed to Pr2NiO4 above 1050°C. Finally, the impact of deposition conditions on the structural and morphological features of the Pr4Ni3O10 films were studied by electron microscopy techniques.

O.P11.40
16:30
Authors : Alistair Simpson1, Patrick Lemoine1*, Preetam Kumar Sharma 1, Barry McLaughlin2, M Strawhorne2, J. Anthony Byrne1
Affiliations : 1, NIBEC, Ulster University, Shore Road, Newtownabbey, BT37 0QB, UK 2, AVX Ltd, 5, Hillman's Way, Coleraine, BT52 2DA, UK

Resume : Multilayer ceramic capacitors (MLCC) are electronic components used for charge storage and switching applications in a wide range of products such as automotive components, smart phones, computers digital cameras, etc. To improve performances, such as volumetric capacitance, MLCC are miniaturised, with thinner dielectric layers, made of smaller individual barium titanite (BT) crystal grains and this is a challenge as smaller grains have reduced permittivity. The other issue is to improve the reliability of these devices as MLCC are processed within a unique manufacturing process which result in oxygen vacancies within the BT layer. After prolonged or repeated usage, the evolution of these defects can result in a drop in the internal resistance and device failure [1] In this study, we investigate this issue on cross-sectioned and polished MLCC devices in pristine and aged conditions; the ageing being carried out using highly accelerated life testing (HALT) [2]. FE-SEM and AFM microscopy show no significant changes in Ni electrode morphology, topography and continuity. Nanoindentation showed that the aged BT was harder that the as received one. Finally, scanning Kelvin probe microscopy (SKPM) show an asymmetry between anode and cathode voltage and field concentration near interfaces. Hence, these techniques have the ability to show changes within the dielectric layer but also at the Ni/BT interfaces, which can contribute to our understanding of ageing mechanisms and help optimise device reliability. 1. T Tsurumi, M Shono, H Kakemoto, S Wada, K Saito , H Chazono Mechanism of capacitance aging under DC-bias field in X7R-MLCCs, J Electroceram (2008) 21:17–21 2. AM Hernández-López, JA Aguilar-Garib, S Guillemet-Fritsch, R Nava-Quintero, Pl Dufor, C Tenailleau, B Durand, Z Valdez-Nava, Reliability of X7R Multilayer Ceramic Capacitors During High Accelerated Life Testing (HALT) Materials 2018, 11, 1900

O.P11.41
16:30
Authors : A. Iljinas1, V. Stankus1, S. Balčiūnas2, M. Ivanov2, J. Banys2
Affiliations : 1 Department of Physics, Kaunas University of Technology, Studentu str. 50, LT-51368 Kaunas, Lithuania 2 Faculty of Physics, Vilnius university, Sauletekio ave. 9/3 817 LT-10222 Vilnius, Lithuania

Resume : Lead-based ferroelectric materials, such as: PbTiO3, PbZrxTi1-xO3 (PZT), La-doped and Nd-doped Pb(ZrxTi1-x)O3 (PLZT), and (PNZT) are widely used in micro- and nanoelectronics. During practical use lead zirconate titanate have problems with to high coercive field and leakage current, short retention, tendency to imprint, and fatigue with usual platinum electrode. These properties of PZT thin films depend on substrate materials, deposition method using measurement frequencies, at al. The deposition conditions, such as: deposition rate, composition and substrate temperature are very important factors in the growing process for PZT film formation. Thin film growth by reactive magnetron layer-by-layer deposition method in vacuum is one of the most promising methods for perovskite phase PZT thin films formation without post annealing. Lead zirconate titanate thin films were grown on a platinum covered silicon substrate using layer-by-layer reactive DC magnetron deposition method. Deposition was done in a 1 Pa oxygen environment on heated substrates (400-600oC). Atomic composition of surface of as-deposited thin films was studied using X-ray photoelectron spectroscopy (XPS). Layer surface was inspected using optical, scanning electron, and atomic force microscope. The crystallographic structure of thin films was investigated with X-ray diffraction (XRD). Polarization dependency on the electric field strength was measured. The frequency was changed from 20Hz to 1MHz. Dielectric properties of lead zirconate titanate (PZT) thin films were measured from 20 Hz up to 100 kHz during cooling cycle at 1K/min cooling rate using Hewlett Packard 4284A precision LCR meter. Dielectric hysteresis was obtained using aixACCT TFAnalyzer 2000 E system. It was obtained that the Pb(Zr0.58Ti0.42)O3 composition film with the dense and uniform morphology was formed at 550°C substrate temperature. It was shown that the microstructure of the deposited films strongly depend on the substrate temperature. The films exhibit columnar growth at all investigated deposition temperatures. P–E hysteresis loops of PZT thin film deposited at 550oC, exhibiting the highest remnant polarization (25µC/cm2) and coercive field (280kV/cm). The sample has relatively low dielectric permittivity, which is around 150.

O.P11.42
16:30
Authors : C. R. Stilhano Vilas Boas, J. M. Sturm, F. Bijkerk
Affiliations : Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente

Resume : The understanding of low-temperature oxygen interaction and diffusion in ultrathin oxide films is a significant challenge. In this work, we analyze the oxygen-oxide interaction through isotope exchange depth profiling (IEDP) with low energy ion scattering (LEIS). The high sensitivity of LEIS enables the correlation of isotope exchange kinetics at surfaces and in-depth penetration with high accuracy. This method was applied to films of zirconium oxide (ZrO2) and molybdenum oxide (MoO3) of 2 to 10 nm, reactively deposited via DC magnetron sputtering. After deposition, the samples were transferred in vacuum and analyzed prior and after exposure to atomic O-16 and O-18 generated by a plasma gun (10^15 atoms.cm^-2.s^-1) at room temperature. With the diffusion profiles obtained, diffusion modes and parameters were determined based on models stated in the literature. In both stoichiometrically deposited oxides, the total penetration depth was not influenced by the layer thickness. However, isotope diffusion was shown to be strongly influenced by the presence of metallic and sub-stoichiometric oxide species. In all cases, a higher isotope diffusion constant was observed in the outermost few monolayers at the surface, with no indication of bulk diffusion through the film. These factors indicate that the oxygen penetration is driven by the formation of a space-charge layer in the oxide surface, a consequence of band bending of the oxide induced by adsorbed atomic oxygen species.

O.P11.43
16:30
Authors : Junsung Ahn, Ho-Il Ji, Hyoungchul Kim, Ji-Won Son, Ho Won Jang, Jong-Ho Lee
Affiliations : 1. High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea 2. Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea

Resume : Epitaxial strain engineering in nanostructured materials has attracted great attention to various electrochemical devices such as solid-oxide fuel cells, all solid-state lithium ion batteries, and semiconductor devices. Especially, notable achievement for enhanced ion transport has been reported in ultra-thin epitaxial and multi-layered films. However, the epitaxial strain engineering is mostly limited below a critical thickness, at which strain is relieved by misfit dislocation. As a result, strain in most oxide thin films is fully released above about 20 nanometer thickness, which hinders application of strain effect to electrochemical devices. Above the critical thickness, herein, we investigate strain effect on fast oxygen ion transport in co-doped ceria thin films. To reliably explore the strain effect on ionic transport property, well controlled out-of-plane conductivity measurement was performed for co-doped ceria thin films. In addition, average strain and strain distribution in thin films was analyzed through HR-XRD and strain mapping in TEM. Consequently, we found that co-doped ceria thin film could be strained by growth strain through the Volmer-Weber (island) growth mode, and also by local lattice strain induced by difference of ionic radius between major dopant and minor codopant. From this presentation, you will get a great inspiration to effectively apply the strain effect to improve performance of various electrochemical devices.

O.P11.44
16:30
Authors : Waqas Hassan Tanveer(a), John Andersen(a), Maroto valer Mercedes(a), Suk Won Cha(b)
Affiliations : (a) Research Centre for Carbon Solutions- Heriot Watt University, School of Engineering and Physical Sciences, EH14 4AS, Edinburgh, UK; (b) School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Daehak dong, Gwanak-gu, Seoul 151-742, Republic of Korea

Resume : Nickel-Gadolinium Doped Ceria (Ni-CGO) anodic films of 300nm thickness (T1), were deposited on 50~300µm thick (T2) zirconia electrolyte supports, by radio frequency (RF) sputtering. The sputtering was done at 25°C and the RF power (P) was varied between 50~200W. Lanthanum Strontium Manganite (LSM/YSZ) cathodes were screen-printed on the other side of the supports. The solid oxide fuel cells (SOFCs) were tested for maximum power densities under the product fuel of CO2 electro-reduced via industrial waste carbon(IWC)1 at a temperature (C) range of 600°C ~ 800°C by voltage (V)-current (I)-power curves. The resistances of various cell components were measured by nyquist plots. From the results of these electrochemical measurements, a fuzzy model was built with T1, T2, P, C, & V as inputs and I as output. Then, the particle swarm optimization (PSO) algorithm was applied to obtain the optimal parameters of the SOFC, which maximizes its power density. Furthermore, high resolution scanning and transmission electron 2D images were used to build an electrochemical model to simulate the reaction kinetics of these optimized IWC-SOFCs. The results showed that the PVD Ni-CGO based IWC-SOFC’s power density can be increased by 45% when using the PSO algorithm when compared with experimental results. Reference 1. W. H. Tanveer, H. Iwai, W. Yu, A. Pandiyan, S. Ji, Y. H. Lee, Y. Lee, K. Yaqoob, G. Y. Cho and S. W. Cha, Journal of Materials Chemistry A, 2018.

O.P11.45
19:00 Graduate Student Award ceremony followed by the social event    
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Functional oxides : -
08:30
Authors : J.E. ten Elshof
Affiliations : MESA Institute for Nanotechnology, University of Twente, 7500 AE Enschede, the Netherlands

Resume : Two-dimensional metal oxide nanosheets are the oxide equivalents of graphene. They are made by delamination of layered metal oxides in water using a combination of acid-base & ion exchange reactions, or by direct bottom-up growth from chemical solutions. The resulting nanoflakes have thicknesses of 0.5-2.5 nm and lateral sizes between 100 nm and tens of micrometers, depending on composition and synthesis process. A wide range of (doped) oxide compositions and 2D planar structures can realized with these methods. Two applications of oxide nanosheets will be demonstrated in this presentation: (1) Nanosheets are 2D single crystallites with only one type of surface termination. As such, they are versatile seed layers for growth of oriented and epitaxial functional metal oxides. Oriented perovskite-type thin films of SrRuO3, (La,Sr)MnO3, Pb(Zr,Ti)O3 and BiFeO3 have been grown on Ca2Nb3O10 and Ti0.87O2 nanosheets using pulsed laser deposition. Depending on the nature of the seed layer, either [001] or [110] oriented perovskite films are formed, and the ferromagnetic and piezoelectric properties are controlled by the domain size and preferential orientation of the as-grown films. (2) MnO2 nanosheets are suitable as active electrode elements for micro-supercapacitors owing to their composition, conductivity and large specific surface area. The fabrication of nanosheet-based microsupercapacitors by ink-jet printing on flexible plastic substrates is demonstrated. As will be shown, their device characteristics are similar to state of the art supercapacitors.

O.12.1
09:00
Authors : Alexis Boileau1, Marie Dallocchio1, Florent Baudouin2, Adrian David1, Ulrike Lüders1, Bernard Mercey1, Valérie Demange2, Maryline Guilloux-Viry2, Wilfrid Prellier1, Arnaud Fouchet1
Affiliations : 1 CRISMAT, CNRS UMR6508, ENSICAEN, Normandie Université, 14050 Caen Cedex 4, France; 2 Univ Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, France

Resume : La0.67Sr0.33MnO3 (LSMO) thin films have been deposited by pulsed laser deposition onto glass substrates (GS) coated with Ca2Nb3O10- nanosheets (NS). NS have been prepared by exfoliation process of KCa2Nb3O10 powder and deposited onto GS using the Langmuir-Blodgett method with different coating levels (fully, intermediately and non-coated substrates). X-ray diffraction and Electron backscatter diffraction mapping confirm the effect of NS to induce the epitaxial stabilization of LSMO films with a strong out-of-plane (001) texture, whereas the growth of LSMO films on pristine substrates exhibit a non-textured polycrystalline phase. The growth temperature was also investigated and demonstrates that the properties of LSMO film deposited on NS at 550°C are close to those the 650°C one whereas a strong degradation of the LSMO crystalline structure is observed without NS. Transport and magnetism measurements have shown that LSMO films grown on NS coated GS exhibit physical properties close to those of a monocrystalline LSMO film deposited on (001)-oriented SrTiO3 substrate used as reference. In contrast, LSMO polycrystalline films have physical properties close to those of the bulk material. This study demonstrates the opportunity to integrate functional (001)-textured LSMO thin films of high quality on GS using a Ca2Nb3O10- NS layer as growth template. The use of a NS layer offers new perspectives for the integration of functional materials on any substrate at moderate temperature.

O.12.2
09:15
Authors : S. P. Ioannou, E. Kyriakides and J. Giapintzakis
Affiliations : Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., PO Box 20537, 1678 Nicosia, Cyprus

Resume : Neuromorphic computing, which resembles synaptic functions of biological neural networks, is emerging as one of the most viable successors of current computing paradigms. The use of established deposition techniques, the safeguarding of Si compatibility, along with the precise control of synthesis, processing and characterization of multifunctional oxide films, is expected to mitigate current CMOS technology bottlenecks, through the production of two-terminal synaptic devices, structured in crossbar arrays. Herein, we present the fabrication of a synaptic device based on the electrochemical delithiation of a highly stoichiometric LiCoO2 (LCO) cathode, and the insertion of the mobile Li ions in a host anode. Deviation from stoichiometry, caused by Li removal, leads LCO to an abrupt resistive switching (RS) with 4 orders of magnitude resistance change, when directly deposited on SiO2(native)/Si substrates. Unlike most filamentary RS devices, a homogenous underlying mechanism is proposed. In order to observe the homogenous RS, a TiO2 anode has been employed, rendering (Au)/LCO/SiO2/TiO2/(SiO2/Si) two terminal devices. Ti is sputtered on Si, and subsequently transformed to TiO2 by in-situ oxidation during the deposition of the LCO overlayer. Highly-stoichiometric, high-temperature (HT) LCO is deposited on top of the Ti layer, via PLD, in an O2 atmosphere at 600 °C, which leads to the in situ oxidation of the Ti into TiO2. Direct deposition of LCO on Ti, however, is conducive to the formation of interfacial parasitic LixTiyO4 phases, reducing the HT-LCO phase, hence limiting the RS effect. It is hereby shown that interposition of a thin sputtered a:SiO2 layer impedes the thermal reaction of Li with Ti, but allows the diffusion of oxygen for the in situ oxidation of TiO2, thus enabling the implementation of synaptic functionalities based on a homogenous RS mechanism.

O.12.3
09:30 Coffee break    
 
Functional oxides : -
10:00
Authors : E. Ferreiro-Vila, L. Iglesias, J. M. Vila-Fungueiriño, F. Rivadulla
Affiliations : Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; Institut d’Electronique et des Systemes (IES), UMR 5214, CNRS – Universite de Montpellier, 860 rue Saint Priest, 34095 Montpellier, France.

Resume : Recent developments in thin-film growth showed the enormous potential of epitaxial stress to tune the properties of thin films. In transition-metal oxides (perovskites, spinels, etc) strain accommodation occurs through the modification of bond-distances and angles, which determines the relative orbital occupation. An important question is whether the ccommodation of epitaxial strain can be modified by growing the films under very different conditions, thus allowing the system to explore different relaxation paths. Here we describe a comparative study of perovskite La2/3Sr1/3MmO3 (LSMO) and spinel CoFe2O4 (CFO) thin films grown by pulsed laser deposition (PLD; far from thermodynamic equilibrium), and by a chemical deposition method (polymer assisted deposition, PAD; close to thermodynamic equilibrium). Our results demonstrate that the elastic and magnetic properties of these oxides are largely determined by the proximity to thermodynamic equilibrium during growth. For example, we have found that the pattern of rotation of MnO6 octahedra in LSMO depends very much of the growth conditions. As a result, the relative contributions to the magnetic anisotropy in this oxide can be controlled during deposition.[1] For the case of CFO, we observed that the cationic arrangement among the different voids of the structure also depend on the growth conditions. As a result, a progressive change in the sign of the Poisson ratio can be induced in thin films of CFO in response to epitaxial stress and temperature, defining a smooth crossover from auxetic to non-auxetic behavior depending on the growth conditions.[2] The results presented in this work are of general applicability for understanding the stress-relaxation mechanism in complex crystalline structures. [1] J.M. Vila-Fungueiriño et al. J. Phys. D: Appl. Phys. 49, 315001 (2016). [2] E. Ferreiro-Vila et al. submitted.

O.13.1
10:30
Authors : Andreas Klein
Affiliations : TU Darmstadt, Germany

Resume : The Fermi energy in semiconductors can often be freely controlled across the whole energy gap by doping. This is not the case in oxides, where different mechanisms exist, which can limit the range of the Fermi energy. These limits can be caused by i) dopants having deep rather than shallow charge transition levels, ii) self-com-pen¬sation where the Fermi energy dependence of the defect formation energy leads to spontaneous formation of compensating defects, iii) the change of the oxidation state of either the cations or the oxygen. The latter is particularly relevant for compounds with transition metal or rare earth cations and has been recently demonstrated to explain the low water splitting efficiency of hematite. It will be demonstrated how the limits of the Fermi energy can be assessed using X-ray photoelectron spectroscopy (XPS). The variation of the Fermi energy can thereby be achieved either by deposition of thin films on different substrates, by deposition of differently doped films, by different surface treatments including oxygen and vacuum annealing, oxygen plasma treatments and water adsorption, or by formation of interfaces with low and high work function metal oxides. Extensive data sets for various oxides, including dielectric, semiconducting and ionically conducting materials are available. The effects will be illustrated using selected materials and the alignment of the Fermi energy limits will be discussed.

O.13.2
11:15 Plenary session 2    
12:30 Lunch    
 
Magnetic oxides : -
14:00
Authors : Arunava Gupta
Affiliations : Center for Materials for Information Technology (MINT), The University of Alabama, Tuscaloosa, AL, USA

Resume : Spinel ferrite thin films have numerous technological applications in areas such as telecommunications (microwave and millimeter wave devices), magneto-electric coupling devices and are also promising candidates for future spintronic devices. Unlike perovskites, the investigation of high quality spinel ferrite films is quite limited, in part because of the complex crystal structure with a large unit cell consisting of many interstitial sites and that the transition metal cations can adopt various oxidation states. Usually films of spinel ferrite such as NiFe2O4 (NFO), grown both by both physical and chemical deposition techniques, suffer from a number of structural and magnetic drawbacks, e.g. formation of antiphase boundaries and high magnetic saturation fields. We show that by using substrates having similar crystal structure and low lattice mismatch, one can avoid formation of antiphase boundaries and thereby obtain magnetic properties comparable to bulk single crystal. We used spinel MgGa2O4, CoGa2O4 and ZnGa2O4 substrates, which have 0.6%, 0.1% and 0.05% lattice mismatch, respectively, with NFO to grow epitaxial films that are essentially free of antiphase boundaries and exhibit sharp magnetic hysteresis characteristics. Moreover, ferromagnetic resonance linewidths similar to those in single crystals are obtained. We have compared these results with NFO film grown on another spinel substrate MgAl2O4, which has 3.1% lattice mismatch, that has antiphase boundaries and clearly exhibits degraded properties. We have also investigated spin transport properties of the films grown on the three substrates via the longitudinal spin Seebeck effect (LSSE). An increase in the spin voltage signal with reduction in lattice mismatch is observed, which is in correspondence with similar improvements in structural and magnetic properties. Improvements in the magnetic and spin Seebeck properties are also observed using the lattice-matched substrates for other spinel ferrites, including CoFe2O4 and Fe3O4.

O.14.1
14:30
Authors : Adrien Teurtrie, Elena Popova, Ekaterine Chikoidze, Niels Keller, Alexandre Gloter, Laura bocher
Affiliations : Laboratoire de Physique des Solides, UMR8502, 91405 Orsay, France and Groupe d’Etude de la Matière Condensée (GEMaC), UMR8635, 78035 Versailles, France ; Groupe d’Etude de la Matière Condensée (GEMaC), UMR8635, 78035 Versailles, France ; Groupe d’Etude de la Matière Condensée (GEMaC), UMR8635, 78035 Versailles, France ; Groupe d’Etude de la Matière Condensée (GEMaC), UMR8635, 78035 Versailles, France ; Laboratoire de Physique des Solides, UMR8502, 91405 Orsay, France ; Laboratoire de Physique des Solides, UMR8502, 91405 Orsay, France

Resume : Bismuth iron garnet (Bi3Fe5O12; BIG) is an insulating ferrimagnet[1]. It possesses functional properties e. g. giant Faraday rotation[2] and magnetoelectric coupling[3]. To further develop its field of potential applications, we aim at enhancing its electrical properties while preserving a robust magnetism. A co-doping strategy is used to synthesize B(CaxY0.5-x)IG thin films. Ca2+ is expected to induce hole carriers while Y3+ is used to control the magneto-optical properties driven by the Bi content. B(Ca0.3Y0.2)IG and B(Ca0.0Y0.5)IG present p- and n-type semiconducting behaviour with resistivity values of 1000 Ω.cm and 10 Ω.cm at 450 K, respectively. A reversible resistive change is unveiled in the n-type B(Ca0.0Y0.5)IG when annealed under neutral/oxidizing atmosphere; the underlying physical mechanisms originating from the oxygen vacancies’ variation[4]. Advanced Scanning Transmission Electron Microscopy coupled with Electron Energy-Loss Spectroscopy (Cs-STEM/EELS) allows us to probe and map locally absorption edges to reveal the atomic and electronic structures. Here, Ca/Y solubility in the BIG lattice was confirmed by STEM/EELS. At higher energy resolution, a clear Fe2+ increase was probed in the B(Ca0.0Y0.5)IG low resistivity state and accounts for the oxygen release. In the p-type B(Ca0.3Y0.2)IG no evidence of Fe4+ could be found indicating a self-compensation with oxygen vacancies. [1] Oikawa JPSJ 74 (2005) [2] Deb JAP 45 (2012) [3] Popova APL 110 (2017) [4] Teurtrie in preparation (2019)

O.14.2
14:45
Authors : Parul Pandey,1, Ching-Hao Chang,2, Angus Huang,3, Rakesh Rana,1, Changan Wang,1, 4, Chi Xu,1, 4, Horng-Tay Jeng,3, 5, Manfred Helm,1, 4, R. Ganesh,6, and Shengqiang Zhou,1
Affiliations : 1 Helmholtz-Zentrum-Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany 2 Leibniz-Institute for Solid State and Materials Research, Helmholtzstraße 20, 01069 Dresden, Germany 3 Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan 4 Technische Universität Dresden, 01062 Dresden, Germany 5 Institute of Physics, Academia Sinica, Taipei 11529, Taiwan 6 The Institute of Mathematical Sciences, HBNI, C I T Campus, Chennai 600113, India

Resume : Atomically sharp heterointerfaces of correlated oxides, given their structural and chemical compatibility, host a rich variety of new electronic and magnetic phases with astonishing properties [1,2]. The emergent phenomenon at the interface is the result of the precise modification of the orbital, electronic, and magnetic structures of the individual constituent layers. The prominent example of such modification at oxide interface physics is high mobility two-dimensional electron gas at the interfaces of two insulators, conducting ferromagnetic layer at an interface of two antiferromagnetic insulators, and orbital reconstruction of electronic systems [1,2]. In particular, heterostructures have served as a sensitive probe by using proximity to an ordered system to bring out latent ordering in an otherwise disordered material. Here, we present a bilayer system composed of SrRuO3, a ferromagnetic metal [3], and CaRuO3, a paramagnetic metal [4]. A detailed experimental study of SrRuO3-CaRuO3 bilayers with various relative widths shows a single magnetic transition temperature which is close to the bulk Tc of SrRuO3, and a net ferromagnetic moment in all samples. At high temperatures, immediately below Tc, the strength of the net moment is directly correlated with CaRuO3 width, while it is inversely correlated at low temperatures. The magnetization results are corroborated well with the transport studies indicating the significance of the conduction electrons in the system. Based on these results, we argue that the CaRuO3 layer develops an oscillating polarization with two contributions: local moments and conduction electrons. The conduction electrons develop Friedel-like oscillations in polarization due to the boundary condition imposed by the ordered SrRuO3 layer. This is inherited by rigid local moments at low temperatures. We also present a simple theoretical model and ab initio simulations to support our picture. 1. H. Y. Hwang et al., Nature Materials 11, 103 (2012). 2. J.H. Ngai et al., Annu. Rev. Mater. Res. 44, 1 (2014). 3. G. Koster et al., Rev. Mod. Phys. 84, 253 (2012). 4. G. Cao et al., Phys. Rev. B 56, 321 (1997).

O.14.3
15:00
Authors : Elodie Martin(a), Francois Roulland(a), Daniele Preziosi(a), Geneviève Pourroy(a), N. Blanc(b,c), N. Boudet(b,c), S. Grenier(b,c), Nathalie Viart(a), Christophe Lefevre(a)
Affiliations : (a) : Institut de Physique de Chimie des Matériaux de Strasbourg, UMR 7504 CNRS-UdS, 23, rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France ; LabEx of Nanostructures in Interactions with their Environment (NIE) (b) : Université Grenoble Alpes – Institut Néel, Grenoble, 38042, France (c) : CNRS – Institut Néel, Grenoble, 38042, France

Resume : Cobalt ferrite, CoFe2O4, (CFO) crystallizes in a spinel structure with the Fd-3m space group. This material has been widely studied for its potential application in electronic devices. The applications require the elaboration of CFO in thin films. While the structure of CFO is very often not cubic any more in these thin films, and while this may have a tremendous impact on their physical properties, there has been until now no determination of the exact structure adopted by CFO in thin films. CFO thin films have been elaborated on MgO (100) at 400°C by pulsed laser deposition with various O2/N2 deposition pressures. Cell parameters and magnetic properties have been investigated as a function of partial pressures. Crystallographic characterizations performed on the samples pointed out a tetragonalisation of the unit cell as a function of the deposition pressure, from c/a > 1 for P < 0.04 mbar to c/a < 1 at high pressure. One of the main consequences of this distortion is the tailoring of the easy direction of magnetization from in-plane at low pressure to out-of-plane at high pressure. This breaking of the original cubic symmetry is therefore the keypoint for the understanding of the physics of these phases and the crystal structure has to be precisely determined. This is a complicated task because of the small amount of matter available in thin films. We were able to complete it via a synchrotron-based resonant X-ray diffraction technique. Diffraction Anomalous Near Edge Structure (DANES) experiments have been recorded at both the cobalt and iron edges using the D2AM experiment set-up of the ESRF BM02 beamline. We then performed a crystallographic Fd3m subgroups analysis and were able to fully determine the crystal structure of the films.

O.14.4
15:15
Authors : 1,2. Anna Mandziak, 2. Juan de la Figuera, 2. Guiomar Delgado Soria, 2. Jose E. Prieto, 2. Fernando Moutinho, 3. Katerina Horakova, 4. Ingo Krug, 1. Michael Foerster, 1. Lucia Aballe,
Affiliations : 1. Alba Synchrotron Light Facility, CELLS, Barcelona E-08290; 2. Institute of Chemical Physics "Rocasolano", Madrid; 3. Institute of Physics of the Czech Academy of Sciences, 182 21 Prague 8, Czech Republic; 4. Freelance scientist, Berlin, Germany

Resume : Antiferromagnetic (AFM) oxide materials in low-dimensional geometries, either in nonmagnetic or magnetic environments, display a rich variety of magnetic behavior. They are very interesting materials to investigate the fundamental physics of finite-size effects in magnetic systems. Despite the limited applications in current technology, AFM oxides are important reference and model systems for studying the interface coupling phenomena that are ultimately exploited in devices such as spin-valves. Furthermore, they are the current focus for next generation of spintronic devices. Here we demonstrate a route for preparing high quality ultrathin ternary transition metal oxide films on a metallic substrate. Nickel oxides with a small content of iron have been grown on Ru(0001) by oxygen-assisted molecular beam epitaxy at elevated temperatures (1150 K). The nucleation and growth is observed in real time by means of Low Energy Electron Microscopy (LEEM. This enables the optimization of the growth parameters. A comprehensive characterization is performed combining LEEM and LEED for structural characterization and PEEM (PhotoEmission Electron Microscopy) with synchrotron radiation for chemical and magnetic analysis via X-ray Absorption Spectroscopy and X-ray Magnetic Linear Dichroism (XAS-PEEM and XMLD-PEEM, respectively). We have been able to obtain high quality 2D islands with atomically flat surfaces and a low density of defects. The high crystalline and morphological quality result in optimized properties with respect to films grown by other methods, such as magnetic domains whose size are larger by several orders of magnitude.

O.14.5
15:30
Authors : 1. Suvidyakumar Homkar, Daniele Preziosi, François Roulland, Christophe Lefèvre, Sophie Barre, Gilles Versini, Cédric Leuvrey, Corinne Bouillet, Nathalie Viart, 2. Sébastien Petit-Watelot, Olivier Copie, Karine Dumesnil, Carlos Rojaz-Sanchez, 3. Morgan Trassin
Affiliations : 1. Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504, Université de Strasbourg, 23 rue du Lœss, BP 43, 67034 , Strasbourg Cedex ; 2. Institut Jean Lamour UMR 7198 CNRS, Université de Lorraine, 2 allée André Guinier, BP 50840, NANCY Cedex, France ; 3. Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Suisse

Resume : The focus of research in Spintronics currently aims at reducing the energy cost for magnetic memory bit manipulation, with particularly great implications for the magnetic storage industry. A possible route involves the control of magnetization through spin current based torque such as Spin-Orbit Torque (SOT). SOT can be realized in a bilayer system where one layer is magnetic, and the second layer is a non-magnetic metal with a high spin-orbit coupling (SOC). In the non-magnetic metal, a spin current is generated via the Spin Hall Effect (SHE) and can be injected into the magnetic layer through the interface. A net torque affects the magnetic layer state. We have considered constructing such a device using Ga2-xFexO3 (GFO) as the magnetic layer and platinum as the non-magnetic layer. GFO, apart from being ferrimagnetic at room temperature, also possesses a strong magneto-electric (ME) coupling which makes it possible to have electric field control of magnetization. We will investigate the impact of the ME effect on the SOT in such GFO/PT bilayer. Using a low energy consuming electric field, the magnetization of GFO can be tuned, offering new avenues towards the decrease of the critical current needed to switch magnetization by SOT. In this work, we will demonstrate the optimization of Ga0.6Fe1.4O3 (001) thin film growth by pulsed laser deposition on SrTiO3 (111) substrates in order to achieve atomically flat surface. Interface quality with the top platinum layer is indeed critical for the SOT efficiency. We have observed the influence of the deposition parameters (fluence, repetition rate, deposition atmosphere and substrate temperature) and films thickness on the surface quality and crystallization. We report the crucial parameters required for obtaining atomically smooth growth. The samples characterizations include structural characterization of the deposited material using X-ray diffraction, RHEED, and transmission electron microscopy, as well as topography by atomic force microscopy. The magnetic properties are probed by SQUID magnetometry and the thickness dependence of the GFO magnetic properties will be presented.

O.14.6
15:45
Authors : T. S Suraj, K. Sethupathy, M. S. Ramachandra Rao
Affiliations : Department of physics, IIT Madras, India-600036

Resume : Generation, transportation and detection of spin in a control manner are very important in spintronic devices [1] There are several ways to generate spin current such as spin Seebeck effect and spin pumping effect [2]. The conversion of charge current to spin current is known as spin Hall effect (SHE) and the inverse phenomenon is inverse SHE (ISHE). The detection of spin is usually realized by the ISHE. Spin Hall magnetoresistance (SMR) arises due to the simultaneous effect of SHE and ISHE in a bilayer heterostructures consisting of ferromagnetic (or ferrimagnetic) insulator (FMI) and a normal metal (NM). Magnetic Proximity Effect (MPE) observed in YIG/Pt complicates the spin transport scenario with additional effects such as Anomalous hall effect (AHE) which attenuate SMR signal.[4,5].Our group has successfully studied Ga: ZnO insertion on Bi: YIG/Pt and observed SMR signals, but the increase in spurious paramagnetic signal hampered the SMR signals with increasing Ga: ZnO thickness[6]. A solution for this is to employ antiferromagnetic moments, which are quite stable to stray fields and MPE. Recent studies in this direction has proved successfull in generating spin current using antiferromagnets NiO/Pt, Cr2O3/W, CuIr and SrMnO3/Pt layers. We have fabricated Antiferromagnetic oxide and metal oxide heterostructures through pulsed laser deposition and demonstrated generation of spin current through angle dependent magnetoresistance measurements (ADMR). The intereface induced magnetic anisotropy additionally contributes a four and six fold symmetry in ADMR measurements. This unsual interface induced symmetry and magnetoresistance effects in all oxide heterostructurs will be presented and discussed in detail. References 1. Matthias Althammer et. al., Phys. Rev. B 87, 224401 (2013). 2. T. Kikkawa et. al., Phys. Rev. Lett. 110, 067207 (2013). 3. E. Saitoh et. al., Appl. Phys. Lett. 88, 182509 (2006). 4. H. Nakayama et al., Phys. Rev. Lett. 110, 206601 (2013). 5. V. Castel et al., Appl. Phys. Lett. 101, 132414 (2012). 6. Matthias Althammer et.al.Appl. Phys. Lett. 110, 052403 (2017).

O.14.7
16:00 Coffee break    
 
Functional oxides : -
16:30
Authors : Ying-Hao Chu
Affiliations : National Chiao Tung University

Resume : In the present era of “Internet-of-Things”, the demand for flexible, light-weight, low-cost, low-power consumption, multifunctional, and environmentally friendly electronics has moved to the forefront of materials science research. Numerous compounds with unique material properties in epitaxial thin film form hold key to future technologies. van der Waals epitaxy (vdWE) involving two-dimensional layered materials can play a crucial role in the expansion of thin film epitaxy by overcoming the bottleneck of material combinations due to lattice/thermal matching conditions inherent to conventional epitaxy. Among the layered materials, mica is a well-known phyllosilicate mineral that can have a remarkable impact on flexible electronics. We confine ourselves to the validity of vdWE of functional oxides on muscovite mica throughout this treatise. These heterostructures with excellent properties are flexible and exhibit high-temperature stability. With such demonstrations, it is anticipated that MICAtronics, vdWE on mica, can reveal unusual properties and emergent phenomena in the realm of high-performance flexible device applications.

O.15.1
17:00
Authors : P. Komissinskiy1, A. Radetinac1, P. Salg1, D. Walk2, L. Zeinar1, A. Zintler1, R. Egoavil3, G. Van Tendeloo3, J. Verbeeck3, L. Molina-Luna1, R. Jakoby2, H. Maune2 & L. Alff1
Affiliations : 1 Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt, Germany. 2 Institute for Microwave Engineering and Photonics, Technische Universität Darmstadt, 64283 Darmstadt, Germany. 3 EMAT, University of Antwerp, 2020 Antwerp, Belgium.

Resume : Perovskites are well known for their wealth of functional properties. However, it is less known that perovskites also harbor materials with a room-temperature conductivity higher than platinum. The perovskite with the highest conductivity reported so far is SrMoO3. For oxide electronics, this opens the path to fully epitaxial perovskite based device stacks making use of the superior properties of epitaxial layers. Here, we show the use of SrMoO3 as bottom electrode in a high frequency agile device where the skin effect compels bottom electrodes with high micrometer thicknesses. Combining epitaxial growth of an extremely thick bottom electrode with an atomically controlled thin functional dielectric layer of (Ba,Sr)TiO3 on top is a huge challenge. We show how perovskites can overcome critical layer thicknesses and how a varactor device with unprecedented performance can be grown using all-oxide pulsed laser deposition.

O.15.2
17:15
Authors : Dong Han1, Mohamed Bouras1, Rahma Moalla1, Claude Botella1, Aziz Benamrouche1, Geneviève Grenet1, Bruno Canut2, Régis Debord3, Valentina Giordano3, Stéphane Pailhès3, Guillaume Saint-Girons1, Romain Bachelet1*
Affiliations : 1 Institut des Nanotechnologies de Lyon, INL UMR5270 CNRS, Ecole Centrale de Lyon, 69134 Ecully, France; 2 Institut des Nanotechnologies de Lyon, INL UMR5270 CNRS, INSA de Lyon, 69621 Villeurbanne, France; 3 Institut Lumière Matière, ILM UMR5306 CNRS, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France

Resume : Because of chemical stability, flexibility, tunable electrical conductivity, and possible integration on Si by epitaxy, perovskite oxides (ABO3) are great alternative to the main thermoelectric (TE) materials based on unstable scarce toxic tellurides. Indeed, n-type TE ABO3 such as transparent La-doped SrTiO3 (LSTO) can exhibit large TE power factor[1]. However, efficient p-type TE ABO3 still remains challenging. P-type transparent conducting Sr-doped LaCrO3 (SLCO) is appealing in this context[2]. After a brief reminder of n-type TE LSTO key results[1,3], we will present high-quality p-type TE SLCO films epitaxially grown on different oxide substrates (LAO, LSAT, STO and DSO) by molecular beam epitaxy (MBE)[4]. The films are flat and fully strained with low mosaicity (<0.1°). The impact of doping level, cationic stoichiometry (A/B) and epitaxial strain (ranging from -2.1% to +1.7%) on the structural and physical properties will be shown and discussed. In particular, optimized SLCO films can present relatively large Seebeck coefficient of about +180 μV/K with electrical resistivity around 1 Ωcm at room temperature. Finally, the integration of these films on Si has been done using a SrTiO3 epitaxial buffer layer with a view to building an integrated micro-thermoelectric module. [1] B. Jalan and S. Stemmer, Appl. Phys. Lett. 97, 042106 (2010) [2] K.H.L. Zhang et al., Adv. Mat. 27, 35 (2015) [3] M. Apreutesei et al., Sci. Tech. & Adv. Mat. 18, 430 (2017) [4] D. Han et al., submitted

O.15.3
17:30
Authors : Seong Guk Jeong, Hyun Bin Kim, Hyung Wook Choi, Seung Hee Choi, Seok Bin Kwon, Young Hyun Song, Jong Hee Kim, Dae Ho Yoon
Affiliations : School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University(SKKU), Suwon 440-746, Republic of Korea Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea

Resume : Among the many kinds of flexible devices, self-powered electronic systems have attracted great interest because they allow for sustainable, long-lasting and remote use of the device without additional energy storage systems. Among them, flexible piezoelectric energy harvesting technology that converts mechanical energy into electric energy have attracted interest. Conventional plastic substrate harvesters showed the possibility of piezoelectric energy generation from repeated deformation and small bending deformation, but due to complicated manufacturing process and size limitations, complex process and size limitations result in the commercialization of piezoelectric self-driving technology. This study is based on a hybrid film of BaTiO3 and resin, and consists of a simple and easy inkjet process. The flexible, large-area piezoelectric hybrid film and Ag electrode layers are printed on flexible prints with only non-contact inkjet processes without high temperature annealing and complex transfer processes. The morphology of hybrid film was analyzed by SEM. The crystallinity of BaTiO3 was confirmed by XRD and Raman spectroscopy. And the All-inkjet-printed energy harvester converts periodically to mechanical deformations into voltage. Furthermore, it was confirmed that the output power increases as the all-inkjet-printed energy harvester is stacked.

O.15.4
17:45
Authors : Wei-Hao Chen, Cheng-Yi Liu
Affiliations : Department of Chemical and Materials Engineering, National Central University, Taoyuan City, Taiwan, R. O. C.

Resume : In this work, ZnO/Cu/ZnO sandwich structure was fabricated as the transparent electrode on the flexible PET substrate. The sputtered ZnO/Cu/ZnO sandwich structure shows a low resistivity (5×10-4 Ω–cm) and high transmittance in the visible region (average around 82 %). To achieve the bendable and flexible properties, we co-sputtering Ti with the Cu metal layer (ZnO/Cu-Ti/ZnO) to enhance the toughness of the ZnO/Cu-Ti/ZnO sandwich structure. Our study shows that the resistivity of ZnO/Cu-Ti/ZnO (50/5/50 nm, 14.2 at.% Ti) is 6.29 × 10-4 Ω-cm and the average transmittance in the visible light region is above 80 %. Importantly, the ZnO/Cu-Ti/ZnO sandwich structure can withstand the reliability test at 85 °C and 85% humidity over 42 days. Also, the bending test shows that the flexibility of the sputtered ZnO/Cu-Ti/ZnO sandwich structure on the flexible PET substrate is greater than that of the sputtered ZnO/Cu/ZnO sandwich structure on the flexible PET substrate. The detail experimental results and discussion would be present in this talk.

O.15.5
Start atSubject View AllNum.Add
 
Growth and characterization : -
08:30
Authors : M. Dias1, A. Frank2, S. Hieke2, S. Fleischmann4,5, J. Harhausen1, R. Foest1, V. Presser4,5, C. Scheu2,3, A. Kruth1
Affiliations : 1-Leibniz Institute for Plasma Science and Technology e.V.(INP), Felix-Hausdorff-Str. 2, 17489 Greifswald; 2-Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany; 3-Materials Analytics, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany; 4-INM – Leibniz Institute for New Materials, 66123 Saarbrücken, Germany 5-Saarland University, 66123 Saarbrücken, Germany

Resume : VOx has been considered as an excellent candidate material for smart windows and solar cells due to its advantageous electronic properties. A plasma ion assisted electron beam evaporation process is used to deposit vanadium oxide on Si(100) substrates. We used different plasma discharge voltages, and currents at a constant working pressure to obtain new correlations between plasma parameters, such as ion velocity distributions, electron densities and presence and states of atomic and ionized species and material properties at the nanoscale. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy were employed to characterize the structure of the thin layers with a nominal thickness of 500 nm. The crystallinity, phase purity, as well as phase identity, vary greatly with discharge voltage. We typically observed in electron beam inconsistencies in oxygen gas flow lead to drastic variations of crystallinity and formation of defect layers throughout the sample bulk. The plasma was studied in-situ by optical emission spectroscopy, multipole resonance probe, and a retarding field energy analyzer during the deposition process. The combined data indicate correlations between the processing parameters and the resulting structure. Subsequently, optical properties and conductivity of samples were measured to access their performance for electrochemical applications.

O.16.1
08:45
Authors : Petr Novák (1), Lucie Prušáková (1), Tomáš Kozák (2), Olga Bláhová (1), Zdeněk Jansa (1), Marie Netrvalová (1).
Affiliations : (1) New Technologies – Research Centre, University of West Bohemia, Plzeň, Czech Republic; (2)Department of Physics and NTIS - European Centre of Excellence, University of West Bohemia, Plzeň, Czech Republic

Resume : Zinc oxide (ZnO) is used in the many applications such as tunnelling layer in solar cells or seed layers for ZnO nanorods. The Aluminium doped ZnO (AZO) films are used as transparent electrode in silicon based solar cells, where indium tin oxide (ITO) is too expensive. Unfortunately, higher resistivity at low thickness (< 200nm) and at low deposition temperatures (< 200°C) prevent wider utilization of AZO, especially in the field of flexible devices. On the contrary, high resistivity of ZnO seed layer is required to avoid external screening effect of ZnO nanorod-based piezogenerator. This work is focused on the possibility to optimize electrical properties of sputtered ZnO and AZO films by controlling of amount of incorporated oxygen at 100°C and 300°C. Oxygen rich conditions were simulated by deposition from ceramic target in Ar O2 atmosphere and oxygen poor conditions were simulated by the co-sputtering from metallic and ceramic target. The relations between oxygen conditions and electrical and optical properties were investigated in detail. The changes were explained by means of dominant internal defects at the the different oxygen conditions during the processing. The control of amount of incorporated oxygen allows to adjust the ZnO film for different applications and to achieve higher carrier concentration of AZO and thus increase the usability as a transparent electrode on the flexible substrates.

O.16.2
09:00
Authors : Florent Baudouin (1), Valérie Demange (1), Valérie Bouquet (1), Bruno Bérini (2), Sophie Ollivier (1), Stéphanie Députier (1), Arnaud Fouchet (3), Maryline Guilloux-Viry (1)
Affiliations : (1) Univ Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, FRANCE (2) Groupe d’Etude de la Matière Condensée (GEMaC), Université de Versailles Saint-Quentin en Yvelines, Université Paris-Saclay CNRS, 45 avenue des Etats-Unis, 78035, Versailles, FRANCE (3) CRISMAT, CNRS UMR 6508, ENSICAEN, Normandie Université, 14050 Caen Cedex 4, FRANCE

Resume : This work aims to develop the growth of functional oxides on low-cost substrates and to propose a new solution for the integration of high quality complex oxides with multifunctional properties for large surface electronics. This integration is often obtained by epitaxial growth of oxides on relatively expensive single-crystalline substrates, which offer a limited choice of materials and crystallographic orientations. The project focuses on the replacement of these single crystalline substrates by quite low-cost (as widely used silicon) or amorphous (as glass) substrates, covered by a crystalline template of molecular thickness (oxide nanosheets), that can be used as seed layers to induce epitaxy of complex oxides thin films on the bottom substrate material. The presentation will be focused on Ca2Nb3O10- nanosheets, obtained by protonation and exfoliation of KCa2Nb3O10 lamellar oxide previously synthetized by solid state reaction and by molten salts reaction. The transfer on Si (100) and SiO2 substrates is performed by Langmuir-Blodgett process. Atomic Force Microscopy shows a smooth covering of the surface. KNbO3 (KNO) and BiFeO3 (BFO) films were then deposited on these nanosheets seed layers by pulsed laser deposition and chemical solution deposition, respectively. Their structural properties were investigated in details. X-ray diffraction measurements show (100) oriented pure BFO and KNO films, which demonstrate the promising utility of nanosheets for epitaxial growth.

O.16.3
09:15
Authors : Li Liu, Misaki Nishi, Phimolphan Rutthongjan, Shota Sato, Masahito Sakamoto, Giang T. Dang, and Toshiyuki Kawaharamura
Affiliations : School of Sys. Eng., Kochi Univ. of Tech.; Res. Inst., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; Res. Inst., Kochi Univ. of Tech.; School of Sys. Eng., Kochi Univ. of Tech.; School of Sys. Eng. & Res. Inst., Kochi Univ. of Tech.

Resume : As a potential material for oxide dielectrics, yttrium oxide (Y2O3) is getting more and more attention because of its excellent thermal and electronic properties, such as high dielectric constant (14~20) and large refractive index (1.7~2.0). Usually, the high deposition temperature and/or vacuum are/is necessary for preparing high quality Y2O3. These strict growth conditions increase the fabrication cost and restrict the commercial applications of Y2O3. So, how to simplify the growth conditions while maintaining the high quality is the key to large-scale application of Y2O3 films. In our work, we prepared Y2O3 thin films at low growth temperature (400 °C) under atmospheric pressure using 3rd generation mist CVD with two solution chambers and one mixing chamber, which can supply the active materials without reactions before arriving the reactor and is an equilibrium reaction system with environmentally friendly and cost-effective characteristics. Experimentally, we obtained the YOx films with deposition rate of 9.0 nm/min, refractive index of 1.74 and dielectric constant of 15~20 under the conditions of yttrium precursor dissolved in MeOH and H2O supported the fabrication. In addition to investigating the effects of oxygen source on the fabrication of YOx films, we also studied the mechanisms of obtaining high quality thin films at low growth temperature. The details about fabrication of high quality Y2O3 thin films by 3rd generation mist CVD will be presented in the conference.

O.16.4
09:30
Authors : Li Zongzhen(1,2), Liu Jie(1), Zhai Pengfei(1), Liu Tianqi(1,2,3)
Affiliations : (1) Institute of Modern Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, China; (2) University of Chinese Academy of Sciences, Beijing 100049, China (3) Lanzhou University, Lanzhou 730000, China

Resume : Amorphous HfO2 is the most used high-k gate dielectric materials for reducing the tunneling leakage current and improving the reliability to overcome the physical limitation of SiO2. However, the electrical properties of HfO2-based devices can be affected by heavy ion irradiation in the space environment. In this study, the amorphous HfO2 films transformed to a monoclinic crystal structure induced by swift heavy ions (SHIs) irradiation was observed directly. The dielectric properties of HfO2 thin films get more deteriorated with increasing ion fluences and electronic energy loss ((dE/dx)e) due to crystallization. Furthermore, the threshold of the ((dE/dx)e) for crystallization is about 10 keV/nm deduced by fitting the relationship between the area of latent track and ((dE/dx)e). The quantitative relationship between microstructures and dielectric properties allows for prediction of device sensitivity to heavy ion irradiation and provides a new method to estimate the threshold of the ((dE/dx)e) for crystallization.

O.16.5
09:45
Authors : Torben Daeneke
Affiliations : RMIT University School Of Engineering Melbourne Australia

Resume : Indium-tin oxide (ITO) is a widely used transparent conductor which finds application in every day electronics such as touch screens and light emitting diodes. One key limitation of ITO is the brittle nature of this ceramic, that arises due to its typical thickness exceeding 10 nm, prohibiting its use in flexible electronics. Herein we report the wafer scale synthesis of highly flexible two-dimensional (2D) ITO nanosheets with a typical thickness of 1 nm. We apply a low temperature liquid metal printing approach that can be utilized to directly deposit 2D ITO onto a desired substrate. The final nanosheets feature two orders of magnitude lower light absorption when compared with graphene, while maintaining high electrical conductance. The 2D ITO, when deposited onto polymer sheets, could be bend to a radius of 2 mm without performance degradation after 1000 bending cycles. Finally, centimeter sized 2D ITO sheets could be synthesized on transparent substrates and fully functional capacitive touch screens were fabricated. The developed technique may enable low cost, printed and flexible optoelectronics, while also providing an alternative to graphene with superior transparency for the creation of van der Waals heterostructures.

O.16.6
10:00 Coffee break    
 
Growth and characterization : -
10:30
Authors : Anna Frank, Miguel Dias, Stefan Hieke, Angela Kruth, Christina Scheu
Affiliations : Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany; Leibniz Institute for Plasma Science and Technology e.V.(INP), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany; Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany; Leibniz Institute for Plasma Science and Technology e.V.(INP), Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany; Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany, Materials Analytics, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany

Resume : Due to increasing energy demands and growing interest in alternative energy production possibilities, various oxides have come into research focus as functional materials in , for example, solar cells or energy storage. However, not only the material itself but also its synthesis procedure should fit the aim of green energy, for example by being energy saving and environmental friendly. A deep understanding of the influence of the deposition process on the quality of the film is crucial. In this work, we present the electron microscopic investigation of a VOx film on Si substrate, deposited by a plasma ion assisted process. The process was monitored in-situ which allows to draw correlations between deposition parameters and film properties. The as-deposited film appears to be X-ray amorphous but cross-sectional transmission electron microscopy (TEM) shows highly crystalline bands inside the otherwise amorphous VOx film. The crystalline bands can be ascribed to variations in the plasma parameters during deposition. In-depth electron diffraction experiments and electron energy-loss spectroscopic (EELS) analysis in TEM indicate the crystalline bands are γ-V2O5, which is the distorted version of orthorhombic α-V2O5. In the amorphous part of the film the atomic arrangement of the nearest neighbor is comparable to the one in γ-V2O5, leading to a similar fingerprint in the EELS data. Combining this insight with the in-situ monitored plasma parameters the deposition process can be tuned for targeted patterning of (VOx) thin films.

O.17.1
10:45
Authors : Matthijn Dekkers, Minh D. Nguyen, Arjen Janssens
Affiliations : Solmates BV (for all)

Resume : Pulsed laser deposition (PLD) has become a very popular technique for experimental studies and has proven itself as a distinctive tool for the manipulation of thin film growth. Nowadays PLD is being considered as a potential production tool to face the challenges in thin film synthesis related to upcoming technology nodes in CMOS manufacturing. New and complex metal oxide thin films and devices are required as computing power according to Moore’s law is no longer being met by scaling alone. The intrinsic differences and unique features of PLD position it as a powerful and complementary tool among the other deposition techniques for advanced thin film growth. These days PLD has matured into commercial equipment enabling application development and pilot production in niche markets. Improved PLD equipment is required to meet the stringent specifications for mass production of oxide nano-electronics. The hardware development is ongoing, and the availability is expected within 5 years. This contribution will describe the current state-of-the -art of PLD for large area deposition and will outline the scalability towards volume manufacturing. Different PLD thin film application development cases for commercial products will be discussed.

O.17.2
11:00
Authors : Michael Nolan, Glen Fomengia, Simon. D. Elliott
Affiliations : Tyndall National Institute, UCC, T12 R5CP, Cork, Ireland

Resume : Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O2-plasma or O3 adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of ?CH3 ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH2O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH3 group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

O.17.3
11:15
Authors : Zsófia Baji, Zoltán Szabó, Zsolt Endre Horváth, Emil Agócs
Affiliations : MTA EK Institute of Technical Physics and Materials Science

Resume : The present work focuses on the deposition, doping and heat treatment of Ga2O3 films with atomic layer deposition (ALD). ALD is a self-limiting layer by layer growth method based on the consecutive chemisorption of precursor gases on a heated substrate surface resulting in a uniform and conformal coverage and a mono-layer by mono-layer growth even on high aspect ratio or nanostructured surfaces. Ga2O3 is a wide band-gap semiconductor very promising due to its photocatalitic properties, gas sensing properties as well as its possible applications as UV transparent conductive oxide, but the lack of a reliable p-dopant hinders its use in photonics. One way to achieve p-type doping may be Zn doping. The present work uses a novel Ga precursor, hexakis-dimethylamino-digallium, which facilitates the use of a wider ALD window than the commonly used precursors (between 130°C and 270°C). The Zn doping was performed using diethylzinc, and water was used as an oxidant. As ALD deposited Ga2O3 films are always amorphous, a number of different heat treatments were used to achieve crystalline β- Ga2O3. The films were deposited with a Picosun Sunale R-100 reactor, the morphology of the layers was characterised with atomic force microscopy, the crystal structure and orientation were examined by X-ray diffraction, transmission measurements were conducted. The bandgaps and dielectric properties of the layers were determined using ellipsometry, and the breakdown voltages were determined.

O.17.4
11:30
Authors : Surbhi Gupta 1, Ayushi Paliwal 1, Vinay Gupta 1, Monika Tomar 2,*
Affiliations : 1. Department of Physics & Astrophysics, University of Delhi, Delhi, India 2. Department of Physics, Miranda House, University of Delhi, Delhi, India

Resume : Optics plays a crucial role in the field of devices and sensors including optical devices which can be considered as the building blocks of optical systems, networks and interconnects. Optics has also gained advantages in the area of information processing utilizing external Electro-optic (EO) modulators having fast response time and are realizable in either reflection or transmission geometry. Among the known ferroelectric EO materials, lead free Strontium Barium Niobate (Sr_x Ba_(1-x) Nb_2 O_6, SBN) possess highest electro-optic coefficient, pyroelectric coefficient and photorefractive properties. The present work reports about the growth of SBN thin films on fused silica substrate utilizing Pulsed Laser Deposition (PLD) technique by varying the laser fluence. The growth was carried out at a fixed ambient oxygen pressure and temperature with the repetition rate of 10Hz of the laser. The structural and morphological properties of the films were examined indicating the substantial use of films for EO modulators. Raman and UV -Visible spectroscopy were utilized to determine the band gap and raman active modes of the SBN thin films. Complex dielectric constant and refractive index of the SBN thin films as a function of laser fluence has been obtained utilizing SPR tool. The EO properties of the prepared SBN thin films has been also investigated utilizing a simplistic approach of Senarmont compensator. The effective birefringence and the EO coefficient as a function of applied electric field was also estimated.

O.17.5
11:45
Authors : Valentina Pinto [a,b], Angelo Vannozzi [a], Fabio Fabbri [c], Fabrizio Mario Ferrarese [a], Achille Angrisani Armenio [a], Francesco Rizzo [a], Giuseppe Celentano [a], Rocco Carcione [b], Fabio Domenici [b], Damiano Palmieri [b], Sara Politi [b], Massimo Tomellini [b], Silvia Orlanducci [b]
Affiliations : [a] Superconductivity Laboratory, FSN-COND, ENEA, Via Enrico Fermi 45, 00044, Frascati (Rome), Italy [b] Department of Chemical Sciences and Technologies, Tor Vergata University, Via della Ricerca Scientifica, 00133 Rome, Italy [c] Superconductivity Laboratory, FSN-COND, ENEA, Via Anguillarese 301, 00123, Rome, Italy

Resume : The superconducting properties of YBa2Cu3O7-d (YBCO) films may be significantly improved through the introduction of nanosized defects. In this work, two new strategies for nano-doped YBCO Chemical Solution Deposition (CSD) are proposed and compared. The first study is focused on Nanodiamond (ND) introduction in YBCO films. This doping strategy has never been reported until our recent preliminary study [1] that showed ND potential for the improvement of YBCO transport properties. Further optimizations of the YBCO-ND CSD process have been accomplished and results are illustrated. Moreover, a second doping option has been evaluated using Gd for the introduction of effective defects. Many studies have been already carried out in the last decade on the replacement of Y3+ in YBCO by other rare earth elements such as Gd3+ to form Y1-xGdxBa2Cu3O7-d mixed compounds. However, the use of Gd added in excess with respect to YBCO has never been studied and is proposed in the present work. YBCO films with ND and Gd addition (YBCO-ND and YBCO-Gd) have been deposited with low-fluorine CSD route on (100) SrTiO3 single crystal. The samples have been characterized via SEM, XRD, VSM, dc resistivity and critical current measurements. Good epitaxial films have been obtained in both cases, and a significant improvement of film morphology and superconducting properties has been observed with respect to pure YBCO. Dopants seem to have beneficial effect on YBCO morphology. Both YBCO-ND and YBCO-Gd films generally show denser, smoother and more connected surfaces. The good morphology corresponds to increased superconducting properties. Higher zero-field critical current densities have been measured in the temperature range from 10 K to 77 K (i.e. 18 and 28 MA/cm2 respectively for YBCO-ND and YBCO-Gd in comparison with 13± 0.1 MA/cm2 of pure YBCO at 10 K). Those results could be mainly ascribed to an improvement of percolation path due to the increase of film density and grain coalescence. However, some differences on the in-field behavior and temperature dependence of transport properties can be observed, evidencing a different role of ND with respect to Gd on YBCO nucleation and growth. [1] V. Pinto, et al .IEEE Trans. Appl. Supercond. 28, (2018) 7500704. DOI: 10.1109/TASC.2018.2800765

O.17.6
12:00
Authors : Hannes Rijckaert,† Glenn Pollefeyt,† Max Sieger,‡ Jens Hänisch,§ Jan Bennewitz,∥ Katrien De Keukeleere,† Jonathan De Roo,† Ruben Hühne,‡ Michael Bäcker,∥ Petriina Paturi,⊥ Hannu Huhtinen,⊥ Maximilian Hemgesberg,# and Isabel Van Driessche,†
Affiliations : †Ghent University, SCRiPTS, Dept. of Inorganic and Physical Chemistry, Krijgslaan 281-S3, 9000 Ghent, Belgium ‡IFW Dresden, Institute for Metallic Materials, Helmholtzstraße 20, 01069 Dresden, Germany §Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany ∥Deutsche Nanoschicht GmbH, Heisenbergstraße 16, 53359 Rheinbach, Germany ⊥University of Turku, Wihuri Physical Laboratory, Dept. of Physics and Astronomy, 20014 Turku, Finland #BASF SE, Advanced Materials & Systems Research, Carl-Bosch-Straße 38, 67056, Ludwigshafen am Rhein, Germany

Resume : Achieving low cost, safe, reproducible, and high performance superconducting thin films of YBa2Cu3O7−δ is essential to bring this material to the energy market. Here, we report on the chemical solution deposition of YBa2Cu3O7−δ nanocomposites from environmentally benign precursors with a low fluorine content. Preformed ZrO2 nanocrystals (3.5 nm) were stabilized in a methanolic precursor solution via two strategies: charge stabilization and steric stabilization. Counterintuitively, charge stabilization did not result in high quality superconducting layers, while the steric stabilization resulted in highly reproducible nanocomposite thin films with a self-field Jc of 4−5 MA cm−2 (77 K) and a much smaller decay of Jc with magnetic field compared to YBa2Cu3O7−δ without nanocrystals. In addition, these nanocomposite films show a strong pinning force enhancement and a reduced Jc anisotropy compared to undoped YBa2Cu3O7−δ films. Given the relationship between the nanocrystal surface chemistry and final nanocomposite performance, we expect these results to be also relevant for other nanocomposite research. Reference: H. Rijckaert, et al., "Optimizing Nanocomposites through Nanocrystal Surface Chemistry: Superconducting YBa2Cu3O7 Thin Films via Low-Fluorine Metal Organic Deposition and Preformed Metal Oxide Nanocrystals," Chem. Mater., 29 [14] 6104-13 (2017).

O.17.7
12:15
Authors : Shannon Poges, Peter Firth, and Zachary Holman
Affiliations : Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona USA, 85281

Resume : Aerosol impaction is a dry spray technique, that when coupled with plasma synthesis of nanoparticles, has the ability to create oxide films of customizable thickness and porosity. We demonstrate the use of our Aerosol Impaction-Driven Assembly (AIDA) system for silica films ranging in thickness from 50 nm – 1 mm, with tunable porosity from 10 – 90%. The ability to manipulate these film properties has generated unique multifunctionality. Through a broad available range in refractive index, our coatings have demonstrated use as antireflective coatings for solar cell applications as well as transparent thermal insulation for windows. Our silica films are composed of 4-6 nm spherical particles, generated from gaseous or liquid precursors through a low pressure dusty plasma synthesis. Film thickness is characterized using ellipsometry or electron microscopy. Porosity is determined using ellipsometry or Brunauer-Emmett-Teller (BET) techniques. Coating durability, thermal conductivity, modeling (thermal, mechanical), and optical properties are also extensively examined where applicable. With resultant films yielding <5% nonuniformity, this novel technique provides reliable coatings for a wide range of applications.

O.17.8

Symposium organizers
Florencio SÁNCHEZInstitut de Ciencia de Materials de Barcelona (ICMAB-CSIC)

Campus de la UAB Bellaterra E-08193 Spain

(+34) 935801853
fsanchez@icmab.es
Maryline GUILLOUX-VIRYUniversity of Rennes 1

Institut des Sciences Chimiques, Solid State Chemistry and Materials Group, Bat 10A, Campus de Beaulieu, 35042 Rennes Cedex, France

+33 2 23235655
maryline.guilloux-viry@univ-rennes1.fr
Valentin CRACIUNINFLPR

National Institute for Laser, Plasma and Radiation Physics and Extreme Light Infrastructure-Nuclear Physics, Magurele, Romania

valentin.craciun@inflpr.ro
Zoe BARBERUniversity of Cambridge

Materials Science Dept.- 27 Charles Babbage Road, Cambridge, CB3 0FS, U.K.

+44 1223 334326
zb10@cam.ac.uk