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2015 Spring

Multifunctionnal Oxides

N

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

Oxides offer unique opportunities to combine in a single system optical, electrical, magnetic, mechanical or chemical properties, suitable for a wide range of applications. The symposium aims to present and discuss the state of the art on oxide films growth or nanostructures with a particular emphasis on the correlation between morpho-structural characteristics and physico-chemical properties.

 

Scope:

 

Innovation in many technological and industrial fields is dependent on sustained research on novel materials in thin films and/or nanostructure form. Improved performance is demanded, alongside reduced energy consumption, and environmentally friendly production and disposal. Multifunctional and tunable materials, offering a range of new device concepts, can contribute to these requirements.

Oxides can be smart materials, with a vast range of controllable properties, such as electrical conductivity, superconductivity, piezoelectricity, magnetism, multiferroic behavior, thermoelectricity, optical transparency, catalytic behavior, etc. Such oxide properties which could lead to innovative applications, require thorough investigation on their correlation with the structural defects induced during the growth for their integration in heterostructures, thin film multilayers, and nanostructures.

The control of growth processes, coupled with accurate characterization tools for structure 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 pertinent parameters allowing the tuning of properties must be fully understood at the local scale as well as at the macroscopic level. In concert with sustainable development, low cost / easy use deposition methods are required, with reduced processing temperatures and solvent use, and the avoidance of polluting and toxic agents.

Following four very successful symposia (more than 200 submitted abstracts) on this topic organized in 2006, 2009, 2011, and 2013 this symposium intends to draw on previous positive experience and continue the established tradition of an interdisciplinary forum that will bring together scientists and engineers involved in various aspects of the synthesis, characterization, device integration and theoretical modeling of multi-functional oxide-based thin films, multilayers and nanostructures to review the latest developments and future trends.

 

Hot topics to be covered by the symposium:

 

  • Oxide films for renewable energy: energy conversion and storage, solid oxide fuel cells, advanced batteries, thermoelectrics, etc.
  • Oxide-based films for spin-electronics, multiferroic and transparent functional oxides
  • Oxides synthesis, structuring and manipulation for nanoscience and nanotechnology
  • Hybrid or nanocomposite structures with novel functionalities
  • Oxides interfaces new properties and applications, defects effects in oxide nanostructures
  • Modeling of oxide nanostructures growth, properties and functionalities
  • New developments in physical vapor deposition methods, wet chemistry, Atomic Layer Deposition for oxide films growth at low temperatures
  • Oxide films and nanostructures based biomaterials.

 

Tentative list of invited speakers:

 

  • Alessandra Boltasseva, [Purdue University, Birck Nanotechnology Center, Indiana, US] : «Plasmonic Ceramics for Applications in Nanophotonics»
  • Klaus Ellmer, [Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany]: «Reactive magnetron sputtering of photoactive oxide electrodes for water splitting»
  • Chia-Chiang Chang, [Industrial Technology Research Institute, Taiwan]: «Oxide film growth deposited by atmospheric pressure plasma technology»
  • Fabio Miletto Granozio, [CNR-SPIN, Naples, Italy]: «Addressing the origin of 2D electron gases at oxide interfaces »
  • Stephen J. Skinner, [Department of Materials, Imperial College London, UK]: «Modulated Oxides - a new route to fast ion conducting electrolytes?»
  • Nathalie Viart, [IPCMS - Département de Chimie et des Matériaux Inorganiques, Strasbourg, France]: «Room temperature multiferroic oxide thin films : the gallium ferrite compounds»
  • Ionela Vrejoiu [Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany]: «Properties of ferromagnetic oxide superlattices with ultrathin layers»

This list will be further adjusted and completed by invited talks selected from outstanding submitted oral contributions, which will be preferentially chosen in order to bring to the stage younger European researchers making significant contributions to the field of oxides.

 

Tentative list of scientific committee members:

 

  • Marin Alexe, [University of Warwick, Coventry, UK]
  • Rolly Gaboriaud, [University of Poitiers, France]
  • Maria Luiza Grilli, [ENEA Casaccia C.R.E., Rome, Italy]
  • Maryline Guilloux-Viry, [University of Rennes 1, France]
  • Michael Lorenz, [Universität Leipzig, Germany]
  • Judith MacManus-Driscoll, [University of Cambridge, UK]
  • Gino Mariotto, [University of Verona, Italy]
  • Magdalena Nistor, [National Institute for Lasers, Plasmas and Radiation Physics , Bucharest-Magurele, Romania]

 

Publications:

 

Proceedings will be published in Thin Solid Films (Elsevier).

 

Sponsors:

 

- FBK - Fondazione Bruno Kessler 
- Lintec Corporation 
- OIKE & Co., Ltd

 

 

 

Start atSubject View AllNum.
09:15
Authors : Hye-Jin Jin, Seol Hee Oh, and William Jo
Affiliations : Department of Physics, Ewha Womans University, Seoul, Korea

Resume : Ferroelectric PbTiO3 is one of the interesting ferroelectrics showing large spontaneous polarization of 75 μC/cm2 at room temperature. In this paper, epitaxial PbTiO3 thin films were deposited on SrTiO3(001) and LaAlO3(001) by laser ablation under various deposition conditions. With an optimized condition, highly c-axis oriented PbTiO3 thin films were achieved and phase formation and lattice variation of the thin films were investigated by x-ray diffraction patterns. In addition, conducting LaNiO3 was used as a bottom electrode to examine electrical properties of PbTiO3 thin films. Depending on the deposition conditions, domain configuration was varied depending on the deposition conditions, because growth of domain is varied by thicknesses of the thin films. To verify local ferroelectric properties and domain switching of the thin films, piezoelectric force microscopy was used.

N.NI.2
 
Piezoelectric, thermoelectric, thermochromic, photoelectric and photonic applications (I) : H. L. Meyerheim, D. Sander
10:30
Authors : Xuan Li, Steve Dunn
Affiliations : Queen Mary University of London

Resume : ZnO nanostructure based dye sensitized solar cell has attracted wide attentions recently. It benefits from high electron mobility, variety of nanostructures and wide range of synthesis routes. However ZnO based DSSC exhibits lower efficiency than those based on TiO2 mainly due to low internal surface area. Core/shell structure was proposed to increase the surface area by adding a rough shell on the ZnO. TiO2 shell was suggested to enlarge the surface area and dye adsorption, suppress the dissolution of Zn2 in the dye solution, block electron recombination and assist fast transfer of injected electrons. TiO2 shell was reported to be deposited using TiCl4 treatment, atomic layer deposition or dip coating. Here we utilized a homemade dip coater and a simple four step dip coating method to fabricate a high quality, thickness controllable TiO2 shell. One dip coating cycle applies one layer of TiO2 shell, which contains dipping in TiO2 sol (0.5 M tetrabutyltitanate, 0.5 M acetylacetone and ethanol), ethanol, DI water and ethanol in sequence. High resolution transmission electron microscopy images confirmed (0 0 4) plane corresponding to anatase phase TiO2 with the shell thickness of 0.692 nm per cycle. UV-Vis showed improved light absorption with thicker shell thickness within 390 nm ? 600 nm wavelength. DSSC devices utilized FTO as substrate, ZnO/TiO2 core/shell structure as photo anode, N719 as sensitizer, iodide/tri-iodide electrolyte, surlyn film as spacer and Pt coated FTO as counter electrode. As a result, Jsc increased from 0.40 mA/cm2 to 1.65 mA/cm2 when the layers of coating increased from 5 to 20. The highest efficiency lay with 20 layers TiO2 coated cell with 0.41%.

N.NII.1
11:15
Authors : C. N. Mihailescu1, 2, E. Symeou1, R. Negrea3, C. Ghica3 and J. Giapintzakis1*
Affiliations : 1Nanotechnology Research Center and Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Avenue,PO Box 20537, 1678 Nicosia, Cyprus 2National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, 077125 Magurele, Romania 3National Institute of Materials Physics, RO-077125 Magurele, Romania

Resume : Crystalline oxides exhibit a plethora of interesting phenomena, providing the basis for novel concepts of oxide-based electronic devices. Among them vanadium dioxide (VO2) has attracted interest for a long time due to its first order metal-to-insulator transition (MIT) near room temperature, TMI ~ 341 K. Across MIT the structural, electrical and optical properties of the material change dramatically. The technologically relevant need of tuning TMI of VO2 has resulted in an impressive number of theoretical and experimental studies investigating the influence of the substrate nature and crystallographic orientation, layer thickness, growing temperature, doping, hydrogenation and interface quality. Among them, the epitaxial strain induced through the lattice misfit between the film and the substrate, is considered to be one of the key factors in controlling the crystal structure, microstructure and further the physical properties of the deposited material. Depending on the used deposition method, the literature shows inconsistency regarding the direction in which factors such as the layer thickness or the growing temperature act as promoters of such induced strain which will further affect the TMI. Another, important but still under debate, parameter in growing VO2 thin films is the maximum growing temperature at which pure (without Ti ions) films can be obtained. Such knowledge is important as the quality of the produced thin film material directly affects the TMI and the abruptness of the MIT. We will present our recent results on the growth by pulsed laser deposition (PLD) of VO2 epitaxial thin films on (0 0 1) TiO2 substrates over a wide temperature range, from 280 to 600°C. The crystal structure has been studied by high resolution X-ray diffraction (HR-XRD) and high resolution transmission electron microscopy (HRTEM), while the quality of the interfaces (microstructure and stoichiometry) has been characterized by HRTEM, STEM (Scanning Transmission Electron Microscopy) and Electron Energy Loss Spectroscopy (EELS). Also, the electrical properties of the deposited thin films, measured over temperature (2 – 400K), will be discussed in correlation with the microstructure.

N.NII.4
11:45
Authors : Madec Querré, Marie-Paule Besland, Valérie Bouquet, Stéphanie Deputier, Etienne Janod, Laurent Cario, Julien Tranchant, Benoit Corraze and Maryline Guilloux-Viry
Affiliations : Institut de Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière BP 32229, 44322 Nantes (FRANCE) and Institut des Sciences Chimiques de Rennes(ISCR), Université de Rennes 1, UMR CNRS 6226, Campus de Beaulieu 263 Av. du Général Leclerc CS 74205, 35042 Rennes (FRANCE)

Resume : Vanadium oxides are well known for their Insulator to Metal Transition (IMT) that makes them good candidates for Resistive Random Access Memory (ReRAM) applications [1]. In particular, the V2O3 system is extremely interesting since two different IMT have been reported [2], one temperature-induced in pure V2O3 far below room temperature (RT) and one driven by electric-field in the Cr-doped Mott insulator (V1-xCrx)2O3 suitable for applications at RT [3]. Recently the use of Mott insulators in a new type of non-volatile ReRAM [4,5] using such electric-field-induced resistive switching (RS) has been proposed [6]. Here we present our work on the deposition process of (V1-xCrx)2O3 thin films by reactive magnetron co-sputtering and pulsed laser deposition. We show that both techniques allow controlling the Cr content, oxidation degree and crystallinity either in situ or after ex-situ annealing. Preliminary results on metal-insulator-metal (MIM) devices show that we retrieve the electric-field-induced RS on these TiN/(V1-xCrx)2O3/TiN symmetric ReRAM cells. Detailed analyses of the synthesis, electrical properties and switching characteristics of the films will be reported. [1] Z. Yang et al., Annu. Rev. Mater. Res. 41, 337 (2011); [2] D. B. McWhan et al., Phys. Rev. Lett. 23, 1384 (1969); [3] P. Stoliar et al., Adv. Mater. 25, 3222 (2013); [4] L. Cario et al., Adv. Mater. 22, 5193 (2010); [5] J. Tranchant et al., Thin Solid Films 533, 61 (2013); [6] ITRS, Emerging Research Devices

N.NII.6
 
Oxides synthesis, structuring and manipulation for nanoscience and nanotechnology (I) : N. Laidani, G. Mariotto
14:00
Authors : F. Ruffino, M. Censabella, V. Torrisi, M. G. Grimaldi
Affiliations : F. Ruffino, M. Censabella, M. G. Grimaldi Dipartimento di Fisica e Astronomia Università di Catania, via S. Sofia 64, 95123 Catania, Italy MATIS CNR-IMM via S. Sofia 64, 95123 Catania, Italy V. Torrisi Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125, Catania, Italy

Resume : SiO2 nanowires (NWs) gain scientific interest due to their intensive blue light emission, one-dimensional luminescence, and wave-guiding characteristic. Recently, a simple, low-cost, versatile and high-throughput solid-state reaction based method was developed for the production of SiO2 NWs: SiO2 NWs can be grown on a Si substrate by first depositing a Au film on its surface and then heating the system at temperatures higher than 1273 K in inert ambient containing trace amounts of oxygen. However, the main concern of such a technique, towards reliable technological applications, is that the fabricated arrays consist of NWs with a very high size dispersion making practically impossible a fine control of the NWs size for specific applications. In this work, we report a new modified methodology to grow, on surface, size-selected ultrathin SiO2 NWs. The methodology involves the high temperature annealing of size-selected colloidal Au nanoparticles (NPs) deposited on Si instead of films. By microscopic analyses we demonstrate that: 1) SiO2 NWs of very low diameter can be grown with respect to those originating by films (till 10 times lower); 2) the size dispersion of the obtained SiO2 NWs is much lower with respect to those originating by films (till 10 times lower); 3) the NWs diameter can be finely tuned by controlling the colloidal NPs starting size; 4) it is possible to decorate such NWs by Au NPs simply by a thermal-induced dewetting process of Au films covering the NWs.

N.NIII.1
14:15
Authors : S. Vankovaa, S. Zanarinia, J. Amicia, F. C?marab, R. Arlettib, S. Bodoardoa, N. Penazzia
Affiliations : aGAME Lab, Dept. Applied Science and Technology - DISAT, Politecnico di Torino, Italy; b Dipartimento di Scienze della Terra, Universit? di Torino, Torino, Italy. e-mail: silvia.bodoardo@polito.it

Resume : We report a Novel WO3 nanostructure that we call nanorolls [1]. The nanocrystals were obtained as self-assembled thin film directly on a transparent conductive substrate. The preparation conditions were mild: the use of HCl was avoided resulting in a eco-friendly hydrothermal method with time of reaction substantially shorter than previously reported HT methods. Interestingly the length of the fibrous structures can be tuned by varying crystallization time. Characterization by FESEM and HR-TEM microscopy evidenced that WO3 nanocrystals are made of rolled nanoflakes with a telescope-like appearance in their final portion. Considering his nano-porosity, electrochemical accessibility, good adhesion to the underlying substrate and the possible presence of nanocavities between the rolled layers, the new material is very versatile from the point of view of possible applications. Nanorolls in fact, are promising for electrochromic devices, water photo-splitting cells, Li-ion batteries and nano-templated filters for short wavelength UV radiation. [1] S. Vankova, S. Zanarini et alii, Nanoscale, 2015, submitted.

N.NIII.2
14:45
Authors : Joe Briscoe1, Nimra Jalali1, Yan Zhi Tan2, Peter Woolliams3, Mark Stewart3, Paul M. Weaver3, Markys G. Cain3 and Steve Dunn,1
Affiliations : 1 Queen Mary University of London, UK; 2 Nan Yang Polytechnic, Singapore; 3 National Physical Laboratory, UK

Resume : Oriented arrays of ZnO nanorods can be grown on a wide range of substrates using low-cost, low-temperature chemical methods. By growing these arrays on flexible substrates they can be utilised in piezoelectric energy harvesting devices, by virtue of the crystallographic alignment of the rods. The piezoelectric output of ZnO-based devices is generally limited due to screening of the polarisation by the high free carrier density, originating from the large number of surface states. We present flexible energy harvesting devices using chemically-synthesised ZnO nanorods, which incorporate a p-n junction and surface passivation to reduce this screening effect. The p-n junction formed between ZnO and a p-type polymer reduces screening by inducing a depletion region, and either the inorganic material CuSCN, or a layer-by-layer polyelectrolyte coating are used to passivate the surface states in the ZnO nanorods. It is shown that with the optimum coating, the peak power output across a resistive load can be increased from 41 µW/cm^2 for uncoated rods, to 434 µW/cm^2 for CuSCN-coated and 426 µW/cm^2 for polyelectrolyte-coated rods, with equivalent increases in open-circuit voltage and short-circuit current. In addition, we measure the electrical impedance of the devices and show that the output voltage correlates well with the electrical time constant of the system, which is related to the rate of screening by the free carriers in the system.

N.NIII.4
15:15
Authors : D. Nunes, T.R. Calmeiro, S. Nandy, J.V. Pinto, A. Pimentel, P. Barquinha, P.A. Carvalho, E. Fortunato and R. Martins
Affiliations : Departamento de Ciência dos Materiais, CENIMAT/I3N, Faculdade de Ciências e Tecnologia, FCT,Universidade Nova de Lisboa and CEMOP-UNINOVA, 2829-516 Caparica, Portugal SINTEF Materials and Chemistry, PB 124 Blindern, NO-0314 Oslo, Norway Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

Resume : Copper-based materials are widely employed with applications ranging from nano-optoelectronics [1] to gas sensors [2]. However, enhanced performance is demanded and in general fine-grained materials result in property improvements [3]. The present work reports localized charge and surface potential variations in pure copper, cuprous oxide and cupric oxide nanowires observed by electrostatic force microscopy and Kelvin probe force microscopy. The copper nanowires were produced via wet synthesis. Their oxidation into cuprous oxide nanowires was achieved through microwave irradiation, while the cupric oxide nanowires were obtained via furnace annealing in atmospheric conditions. The Cu nanowires displayed different energy levels of trapped charges along their length, the presence of structural defects, acting as a different potential energy level in the nanowires may justify this behavior. The work functions of the Cu-based nanowires, obtained using a sputtered metal film as control, appear as: CuO > Cu > Cu2O. Structural characterizations was carried out by X-ray diffraction, transmission electron microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. [1] V. Figueiredo, E. Elangovan, G. Gonçalves, P. Barquinha, L. Pereira, N. Franco, E. Alves, R. Martins, E. Fortunato, Applied Surface Science, 254 (2008) 3949-3954. [2] M. Kevin, W.L. Ong, G.H. Lee, G.W. Ho, Nanotechnology, 22 (2011) 235701. [3] D. Nunes, A. Pimentel, P. Barquinha, P.A. Carvalho, E. Fortunato, R. Martins, Journal of Materials Chemistry C, (2014).

N.NIII.6
 
Oxides ionic conductivity, photoactivity, sensing and electrochemical properties (I) : T. Yamamoto
16:00
Authors : Stephen Skinner
Affiliations : Imperial College London, Department of Materials, Exhibition Road, London, SW7 2AZ, UK

Resume : In the search for efficient and durable solid oxide fuel cells there is an increasing interest in the application of thin films as both model systems and micro devices in an effort to reducing operating temperature and enhance transport properties. Much of the controversy regarding the nature of conduction in thin films has stemed from the indirect nature of the measurements. Our recent studies have focussed on developing our understanding of the ionic conduction in model thin film systems on insulating substrates, deposited by PLD, and in developing new modulated structures that exploit alternative conduction mechanisms. Here we will discusss the oxygen transport in two systems: oriented La4Ni3O10 and single crystal CeNbO4.25.

N.NIV.1
17:00
N.N.PI.2
17:00
Authors : Kushnirenko V.I. (1), V.S. Khomchenko (1), P.V. Demydiuk (2), O.S. Lytvyn (1), T.V. Zashivailo (3)
Affiliations : (1) V.Lashkarev Institute of Semiconductor Physics, NASU, Pr. Nauki 45, Kiev 03028, Ukraine; (2) Institute of Materials Science Problems, NASU, Krzhizhanovskogo 3, Kiev 03680, Ukraine; (3) National Technical University of Ukraine “КРI”, Pr. Pobedi 37, Kiev 03056, Ukraine

Resume : We report an influence of Ag-doping and post-growth hydrotermal annealing on structural and luminescent properties of ZnO thin films. The ZnO films were prepared by reactive rf-magnetron sputtering of zinc targets onto different types of substrates (Si, Al2O3). For Ag doping of the ZnO films, the close space sublimation method (CSS) was used at atmospheric pressure in air at temperatures of 500°C and of 570°C for 1 h. For the ZnO film doped at temperature of 500°C, the Ag concentration makes 0.03 at% and, for the temperature of 570°C, it makes 0.3 at%. After CSS processing, the undoped ZnO and ZnO:Ag films were annealed at temperature of 600°C in a wet media for 1 h. Obtained ZnO:Ag samples as well as reference undoped ZnO films were studied by X-ray diffraction (XRD) technique, atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy at room temperature. XRD results indicated that all the ZnO films have a polycrystalline hexagonal structure. The PL spectra of the films consist of UV band and visible (VIS) bands. The former corresponds to near band edge (NBE) excitonic emission, and these latter are due to the structural defects and impurities. Presented samples have different defects that are generated at the growth and/or treatment, and this is reflected in the visible defect-related PL spectra. After Ag doping, the intensity of UV band increased and the full width at half maximum (FWHM) for this band is narrowed as compared to their reference films, and the wide VIS bands are suppressed. The better UV emission was obtained for the ZnO films grown on sapphire substrate. Origin of observed emission bands is discussed.

N.N.PI.3
17:00
Authors : A. Hadri1, C. Nassiri1, FZ. Chafi, M.Loghmarti1, T. Slimani Tlemҫani1 and A. Mzerd1*
Affiliations : 1University Mohammed V-Agdal, Faculty of Sciences, Physics Department, LPM, B.P. 1014, Rabat, Morocco.

Resume : In the present work pure ZnO, In doped ZnO (IZO) and In, F co-doped ZnO (IFZO) films were successfully synthesized on glass substrates by the chemical spray technique at 350°C, without any additional surfactant or catalytic agent. The effect of dopant concentration ratio on the structural, optical and electrical properties was studied. X-ray diffraction analysis indicates that the films have polycrystalline nature and some differences in the intensity of the peaks and preferential growth, depending on the doping ratios, were observed. The Raman spectra confirm the hexagonal structure of the deposited films, and demonstrated an enhancement of the vibrational mode of (2LA) of doped and co-doped films as compared to undoped films.No extra phases involving zinc, indium and fluorine compounds were observed. The grain size of the films decreased from 49.1 nm for pure ZnO to 31.5nm for In, F co-doped films. The deposited films showed an average transmittance above 70 %, in the wavelength range of 450-700 nm. A minimum electrical resistivity, in the order of 5.0×10-2 Ω.cm was obtained. Moreover, the electrical properties of doped and co-doped films were enhanced after annealing at 350 °C. It was found that annealed thin films showed a decrease of one order of magnitude of the resistivity values. Such a transparent and conducting thin film can be suitable for optical and electrical applications owing to their low resistivity combined with high transmittance in the visible range.

N.N. PI.4
17:00
Authors : P. Fuchs*, J. Steinhauser, H. Hagendorfer, Y.E. Romanyuk, A.N. Tiwari
Affiliations : Laboratory for Thin Films and Photovoltaics, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Duebendorf, Switzerland

Resume : Aluminium doped zinc oxide (ZnO:Al) thin films were prepared by a low temperature (T<150 °C at any step) chemical bath deposition method. The conductivity of the as-deposited films improves by a factor of 10^3-10^4 after ultraviolet (UV) light exposure. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements were conducted to monitor chemical changes upon UV exposure, which include the desorption of chemisorbed oxygen species (CO_2, O_2, OH) and, possibly, the photolysis of the ZnO lattice. The behavior of UV treated samples in different atmospheres was characterized by FTIR, transmittance and Hall measurements. Highly transparent (transmittance >80% in the visible range) Zn:Al thin films with resistivities down to 3.5*10^(-3) Ωcm were integrated as front electrodes in thin film CIGS solar cells. *corresponding author: peter.fuchs@empa.ch, phone: +41 58 765 6124

N.N. PI.8
17:00
Authors : A.U. Abuova1, E.A. Kotomin2, Yu. A. Mastrikov2, T.M. Inerbaev1, A.T. Akilbekov1
Affiliations : 1L.N. Gumilyov Eurasian National University,Mirzoyan str.2, Astana, Kazakhstan; 2Institute of Solid State Physics, University of Latvia, Kengaraga str. 8, Riga, Latvia;

Resume : Solid oxide fuel cells (SOFC) are of great technological interest as they offer high efficiency for energy conversion in a clean way. Because of their diversity in structures, chemical composition, and high stability, transition metal perovskite oxides are widely used in SOFC components. In order to find optimal materials, ab initio density functional theory (DFT) is currently used to design new materials and catalysts for intermediate temperature oxygen reduction reaction. In particular, the catalytic role of Ag in oxygen adsorption and dissociation on oxide/perovskite surfaces so far is not clear. We present and discuss the results of GGA+U calculations of the atomic and molecular oxygen adsorption on the LaMnO3 (001) surface, which serves as a model material for SOFC cathode, in the presence of Ag adsorbate with different coverages. The bond length and bond population of adsorbed O2 molecules indicate that Ag induces O2 dissociative adsorption. The most energetically favourable adsorption sites on both MnO2- and LaO-terminations have been determined, the electron charge transfer between the O2 , Ag and LMO surface has been analyzed.  

N.N. PI.9
17:00
Authors : William Chamorro, Aotmane En Naciri, Yann Battie, Patrice Miska, David Horwat,
Affiliations : Université de Lorraine, Institut Jean Lamour, UMR7198, Nancy, F-54011, France LCP-A2MC, Institut Jean Barriol, Université de Lorraine, 1 Bd Arago, 57070 Metz, France

Resume : ZnO thin films are often used in optoelectronic devices as luminescent films or transparent electrodes due to optical properties as a large exciton energy (nearly 60 meV) a large bandgap energy (E_g) in the near UV region. However, there exists a wide dispersion of the ZnO E_g values reported in the literature. The variation could be due to the determination technique or the experimental conditions during the ZnO thin films growth. However, there is so far no clear understanding for this deviation. This work presents the synthesis of ZnO thin films by reactive magnetron sputtering and their characterization. The films have been synthesized with different O2 percentage in the Ar:O2 reactive gas mixture. From ellipsometric measurements, strong variations of Eg are observed with the synthesis conditions. Under zinc-rich conditions the presence of zinc interstitial introduces shallow donor (electrically active) defects below the conduction band modifying the absorption energy (Eg-abs) and the emission energy (Eg-em) near the band edge as probed by ellipsometry and photoluminescence, respectively. It was possible to establish an empirical relationship to relate Eg-em and Eg-abs and the Urbach energy for all experimental conditions. Thereby, it is possible to rationalize the bandgap energy dispersion in two electrostatic interaction regimes: exciton-defect or exciton-phonon interaction dominates in films with a large or low density of shallow donor defects, respectively.

N.N. PI.10
17:00
Authors : Alina Matei (1,2), Vasilica Tucureanu (1), Ileana Cernica (1), Bogdan Bita (1), Mihai Danila (1), Iuliana Mihalache (1), Lucia Dumitrescu (2)
Affiliations : (1) National Institute for Research and Development in Microtehnologies IMT-Bucharest, Romania (2) Transilvania University of Brasov, Research Centre Renewable Energy Systems and Recycling, Brasov, Romania

Resume : Zinc oxide (ZnO) powder is a versatile material due to inherent properties and their potential applications in industrial and high-technology areas. In this paper, ZnO was prepared by the chemical method, followed by annealing at different temperatures ranging from 400 ºC to 800ºC for 60 minutes in air atmosphere. The effect of the annealing temperature on the structural properties of nanocrystalline ZnO powders were analysed by using Fourier transformed infrared (FTIR), field emission scanning electronic microscopy (FE-SEM), X-ray diffractometry (XRD), while optical properties were studied by photoluminescence (PL) measurements. FE-SEM images indicate an increasing size of ZnO nanoparticles when the annealing temperature varied from 400ºC to 800ºC. Also, the XRD analysis reveals the formation of single phase ZnO with wurtzite structure, and size of crystallite in the range of 9-37nm. The PL measurements were carried out at room temperature and displays one emission peak in UV region (∼380nm) due to exciton emission, along with peaks in visible spectral region due to Zn or oxygen vacancies (defects), the intensity of each bands depends on the annealing conditions. The results was confirmed that the annealing temperature has significant influence on the average particle size, degree of crystallinity and optical properties.

N.N.PI.11
17:00
Authors : S. Boscarino 1,2*, G. Torrisi3, I. Crupi2, A. Alberti4, S. Mirabella2, F. Ruffino1,2, F. Simone1, A. Terrasi1,2
Affiliations : 1) Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania, Italy 2) MATIS IMM-CNR, via S. Sofia 64, 95123 Catania, Italy 3) Distretto Tecnologico Sicilia Micro e Nanosistemi, via Strada VIII 5, 95121 Catania, Italy 4CNR-IMM, via Strada VIII 5, 95121 Catania, Italy

Resume : We present a study on the ion irradiation effects in Al doped-ZnO (AZO) thin films (100 nm). Samples, grown by sputtering on glass or plastic substrates, were irradiated with Ar+ and O+ at 30 keV (ions stopped into the AZO) or 350 keV (ions stopped into the substrate), and 3x1015 to 3x1016 cm-2 fluencies. Thermal treatments up to 400 °C were performed. We found an increase of the crystalline domain size and relief of the lattice strain in all the irradiated films. A huge decrease (more than 2 orders of magnitude) of the resistivity was measured after O+ at 350 keV or Ar+ at 30 keV, while a strong increase is found for O+ at 30 keV. Similar modifications were obtained on as grown samples only after thermal processes at 400 °C. Optical transmission (80%, UV-IR range) and band gap are not deteriorated by ion irradiation. Our data show as all ion irradiations produce structural improvements similar to a high T thermal a annealing, while only for O+ at 30 keV detrimental effects on the electrical properties are observed. Two main results emerge from our study: 1) the role of oxygen is predominant with respect to the structural quality (grain size and strain) in controlling the electrical properties of the AZO; 2) irradiation with passing O+ or implanted Ar+, is a suitable and efficient alternative to high temperature thermal processes to get performing AZO thin films, especially for plastic flexible substrates where thermal processes higher than 150 °C are forbidden.

N.N. PI.13
17:00
Authors : L. Khomenkova1, A. Ziani2, C. Frilay2, Yu. Polishchuk1, O. Kolomys1, V. Kladko1, X. Portier2
Affiliations : 1) V. Lashkaryov Institute of Semiconductor Physics, 45 Pr. Nauky, Kyiv 03028, Ukraine; 2) CIMAP/ENSICAEN, 6 Blvd. Maréchal Juin, 14050 Caen cedex 4, France

Resume : Pure and doped ZnO films have attracted considerable attention due to their micro-, photovoltaic and optoelectronic applications. In present work we studied structural and light emitting properties of Tb-doped ZnO by means of X-ray diffraction, Raman scattering and photoluminescence methods versus annealing treatment. The films were grown on different substrates (silicon, fused quartz and sapphire) and annealed at 600 and 900°C for 1 h in air. It was observed that as-deposited films are stressed and polycrystalline with the grains with the preferable orientation in (002) direction. Their sizes were estimated to be about 11 nm (sapphire), 20 nm (Si) and 27 nm (quartz). An anneal treatment stimulates the increase of ZnO grain sizes with temperature, keeping the same trend versus type of substrate. Analysis of PL properties showed that as-deposited films have a weak emission in UV spectral range corresponding to exciton recombination in ZnO. An annealing causes its enhancement and simultaneous appearance of visible broad PL band in the range of 540-600 nm. The highest emission was detected for the films grown on quartz substrate that can be correlated with the observation of larger ZnO grains. The emission of Tb ions was quenched due to their possible agglomeration, confirmed by the appearance of Tb2O3 grains with (222) orientation and with an average size of about 30 nm upon annealing at 900°C.

N.N. PI.14
17:00
Authors : F. CISSE (1,2), Y. CORREDORES (1), A. LE FEBVRIER (2), X. CASTEL (1), R. SAULEAU (1), S. DEPUTIER (2), V. BOUQUET (2), R. BENZERGA (1), M. GUILLOUX-VIRY (2)
Affiliations : (1) IETR, UMR 6164/IUT de Saint-Brieuc/Université de Rennes 1, 18 rue Henri Wallon, 22004 SAINT-BRIEUC, et 263 avenue du Général Leclerc, 35042 RENNES, FRANCE, Phone: +33 296 609 653, Fax: +33 296 609 652, e-mail: xavier.castel@univ-rennes1.fr; (2) ISCR, UMR 6226/Université de Rennes 1, 263 avenue du Général Leclerc, 35042 RENNES, FRANCE

Resume : Ferroelectric oxide films are promising candidates to build miniaturized and reconfigurable planar devices at microwaves since their dielectric permittivity can be tuned under an external DC electric field. The KTa1-xNbxO3 (KTN) ferroelectric oxide exhibits one of the highest tunability (in terms of permittivity) under moderate biasing, ensuring both size reduction and reconfigurability of the microwave devices printed thereon. However intrinsic KTN dielectric loss contributes to significant insertion loss of such devices. In this work, two routes are investigated to reduce the losses in the devices. The first one is an intrinsic route consisting in doping the KTN material with MgO. Doped and undoped KTN films are grown by pulsed laser deposition on sapphire substrate and characterized by XRD and SEM. After patterning the coplanar waveguide devices (transmission lines and stub resonators), KTN dielectric constants are retrieved from microwave measurements between 1 GHz and 20 GHz, and discussed. Frequency agility and insertion loss of the resonators are compared with those of undoped films. The second route to further enhance the loss reduction consists in confining the KTN material only in efficient regions of the devices and to remove it in ‘non-critical’ areas. An original fabrication process based on UV-laser local microetching is implemented for this purpose. Microwave measurements are performed on resonators patterned on the confined doped films, compared and discussed.

N.N. PI.16
17:00
Authors : Matthew R. Farrow, John Buckeridge, C.Richard A. Catlow, Louis F.J. Piper, David O. Scanlon, Scott M. Woodley, and Alexey A. Sokol
Affiliations : Department of Chemistry, University College London;Department of Chemistry, University College London;Department of Chemistry, University College London; Department of Physics, Binghamton University, (NY); Department of Chemistry, University College London and Diamond Light Source Ltd., Harwell Science and Innovation Campus, Diamond House, Didcot, UK;Department of Chemistry, University College London;Department of Chemistry, University College London

Resume : La doped BaSnO3 is a promising n-type semiconductor with a very high number of electron carriers and, from the modeller’s point of view, has a great advantage in its structural simplicity; the material being a straightforward cubic perovskite. As it is also a wide-gap material, it is an excellent transparent conducting oxide. Insight into its electronic properties will be of fundamental importance for the whole field. The majority of current theories for this class of material are either based on near-free electron approximation and neglect the actual atomic structure or employ ab-initio periodic techniques which are limited to relatively high carrier concentrations. Our recently developed atomistic approach maps the electronic structure of the material on an atomically resolved model and includes polarisation-screening coupled to interatomic interactions. We apply this method to explore the electron distribution in La-doped BaSnO3 and use it to derive distributions of the electrostatic potential in the system, which controls the band alignment. The band offsets thus obtained are in good agreement with experiment. Building on this development we have undertaken an investigation into defect properties of this material using hybrid QM/MM embedded cluster calculations with the ChemShell code. The focus has been on vacant and interstitial sites in all three sublattices as well as Sn and La doping into the Ba sub lattice.

N.N. PI.17
17:00
Authors : S.H. Mousavi, E. Koushki, S.A. Jafari
Affiliations : Department of Physics, Shahrood University of Technology, Shahrood, Iran

Resume : A simple method was used to deposit the aluminium oxide thin films. The thin films were prepared by reactive magnetron sputtering on soda glass substrate and the effect of growth condition on optical properties of thin films was studies. Structural and optical properties of thin films were characterized and their optical constants were measured. Results revealed formation of cubic aluminium oxide phase. The average grain size of 25 nm was observed by scanning electron microscopy images. Optical spectra of thin films are measured. The refractive index and extinction coefficient of the thin films are also measured where the thin films exhibited refractive indexes more than 1.65 at visible wavelengths. The properties exhibited by the aluminium oxide thin films could be useful for high refractive index transparent coatings.

N.N.PI.21
17:00
Authors : M. Nasui, T. Petrisor Jr., R.B. Mos, M.S. Gabor, A. Mesaros, L. Ciontea, T. Petrisor
Affiliations : Technical University of Cluj–Napoca, Str. Memorandumului 28, 400114, Cluj-Napoca, Romania

Resume : The environmentally friendly fluorine-free propionate chemical solution deposition route has been developed for the epitaxial growth of YBa2Cu3O7-x (YBCO) superconducting films. In the present work, metal acetates are used as reagents to prepare a YBCO fluorine-free precursor solution. In order to determine the thermal decomposition behavior, the precursor powder obtained by drying the precursor solution was investigated by thermogravimetric analysis coupled with mass spectrometry and differential thermal analyses. The precursor films were deposited on SrTiO3 single crystal substrates by spin coating and subjected to a single–step thermal treatment. Fourier Transformed Infrared spectroscopy was used to study the decomposition of the films. The films have been structurally and morphologically characterized by X-ray diffraction and atomic force microscopy, respectively, and the superconducting properties have been measured by SQUID. The film composition was investigated by Auger electron spectroscopy. The as-deposited YBCO films show a sharp texture and good superconducting transport properties with Tc = 90 K (R=0) and Jc = 0.8 MA/cm2, respectively. Acknowledgements The research leading to these results has received funding from the EU-FP7/2007-2013 under No. 280432, EUROTAPES project and from Post‐Doctoral Programme POSDRU/159/1.5/S/137516, project co‐funded from European Social Fund through the Human Resources Sectorial Operational Program 2007‐2013.

N.N. PI.24
17:00
Authors : D. Caffrey. I.V. Shvets, K.Fleischer
Affiliations : Trinity College Dublin, AMBER

Resume : Aluminated ZnO (AZO) is a widely used TCO for thin film solar cells and other optoelectronic devices. Depending on doping, the band gap of AZO is found around 3.4 eV limiting the amount of UV light actually transmitted into thin film solar cells or UV sensors with an AZO front contact. Mg inclusion above x=0.2 in form of Zn1-xMgxO:Al has proven to be an effective way to increase the band gap. More important the refractive index of the material is substantially lowered, making it a good candidate for internal anti-reflective layers in solar cells or photo detectors [1]. However, the high Mg content is detrimental to the electrical properties of the material as the scattering at the Mg sites leads to a reduction in carrier concentration and mobility [2, 3]. AZO/MgO superlattices are being investigated as a means to overcome this limitation. Individual layer thickness is low in comparison to the wavelength of visible and UV light resulting in the superlattice behaving as an effective medium. Samples are grown from AZO and MgO targets via magnetron sputtering. The refractive index, bandgap, mobility and conductivity are discussed in terms of crystallographic and structural properties. Results are compared to previously deposited ternary Zn1-xMgxO:Al. [1] K. Fleischer; E. Arca, et al., Sol. Energy Mater. Sol. Cells 101, (2012), 262 [2]J. G. Lu; S. Fujita, et al., Appl. Phys. Lett. 89, (2006), 262107 [3] K. Fleischer; E. Arca, et al., Appl. Phys. Lett. 101, (2012), 121918

N.N. PI.25
17:00
Authors : Viktor Strelchuk, Andrii Nikolenko, Kateryna Avramenko, Рetro Lytvyn, Pierre Tronc, Chan Oeurn Chey, Omer Nur, MagnusWillander
Affiliations : Viktor Strelchuk; Andrii Nikolenko; Kateryna Avramenko; Рetro Lytvyn - V. Lashkaryov Institute of Semiconductor Physics National Academy of Sciences of Ukraine Pierre Tronc - Centre National de la Recherche Scientifique, Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris Chan Oeurn Chey; Omer Nur; MagnusWillander - Department of Science and Technology, Link?ping University

Resume : This report represents the results of structural and optical studies of Mn-doped ZnO nanorods (NRs) synthesized by aqueous chemical growth at nominal Mn concentrations of 10, 15 and 30%. The investigated samples represent arrays of straight and well-aligned ZnO NRs with clear hexagonal facets and average diameter varied from 50 to 500 nm depending on the nominal Mn content. Raman and XRD measurements showed that the investigated ZnO NRs have wurtzite structure with high crystal quality. Successful incorporation of Mn into the host lattice of ZnO is evidenced by the appearance of additional Raman modes and confirmed by EDS measurements. Energetics of the incorporated Mn ions relative to the band structure of ZnO is studied using photoluminescence (PL) and optical absorption spectroscopy. Formation of secondary tetragonal spinel phase of ZnMn2O4 in the NRs grown at nominal Mn content xMn ≥ 15% is found by the corresponding phonon modes in the Raman spectra. Spatial distribution of both structural phases coexisting along the individual ZnO NRs is studied for the first time. The investigated ZnO:Mn NRs showed clear magnetic contrast in magnetic force microscopy (MFM) experiments, providing the evidence of in-plane ferromagnetic magnetization in individual ZnO:Mn NRs at room temperature. Thus, we report simple and easy way of synthesis of high-quality dilute magnetic semiconductor nanostructures based on ZnO to be used in spintronic applications. This work was supported by NATO SfP Grant 984735.

N.N.PI.27
17:00
Authors : A. Waroquet, V. Demange, S. Députier, V. Bouquet, M. Guilloux-Viry
Affiliations : Institut des Sciences Chimiques de Rennes, UMR 6226-UR1, Rennes, France

Resume : Lead-free thin films of the potassium niobate KNbO3 have attracted attention in microelectronic and electro-optic fields due to its ferroelectric and optical properties (high electro-optic and non-linear optic coefficients). This work deals with the study of epitaxially grown KNbO3 thin films synthetized by pulsed laser deposition from targets prepared with different potassium contents and at different temperatures on (100) SrTiO3 and R-sapphire substrates. Unexpected results are evidenced from the comparison between stoichiometric and non-stoichiometric films in particular in term of stabilized KNbO3 phases. The results also show a change in color, in lattice parameters and, for some cases, in orientation relationships with the substrate. Formation of the layered K4Nb6O17 phase is also observed under some conditions. Films were characterized by x-ray diffraction, x-ray mapping of the reciprocal space, scanning and transmission electron microscopy, and energy dispersive spectroscopy.

N.N.PI.31
17:00
Authors : A. Mariscal(1), A. Quesada(2), I. Camps(1), J.F. Fernández(2), R. Serna(1)
Affiliations : (1) Laser Processing Group, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain; (2) Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, Madrid 28049, Spain

Resume : Europium oxide films have received large attraction for their use in the fields of microelectronics, spintronics, magnetism and photonics. The fabrication of crystalline high quality pure Eu-oxide thin films is challenging, growth under oxide gas environment and high temperature processing are usually necessary. However, such processing can lead to the formation of Eu-silicides when Si substrates are used. [1] In this work, we report the growth of Eu-oxide thin films (200 nm) in vacuum by pulsed laser deposition, from a pure sintered Europium oxide bulk target at room temperature on Si substrates. In order to avoid the reaction of the Eu-oxide film with the Si substrate, a buffer layer of amorphous Al2O3 was deposited previously on the substrate. For comparison a reference film with no buffer layer was deposited. Post-deposition annealing treatments where performed under different conditions. As result, according to the analysis of Raman and X-ray Diffraction (XRD) measurements, crystalline films are formed, where both cubic and monoclinic phases can be identified. No silicide formations have been seen. Photoluminescence has been studied under laser excitation at 355 nm. All the films show intense and narrow peaks that are attributed to the intra 4f-transitions of Eu3+ ion in a crystalline host. However, clearly different emission spectra are observed as a function of the specific crystalline phases present. Changes in the magnetic hyperfine 5D0 – 7F0 transition at 612 nm confirm the crystal field effect and its influence over energy level splitting. The relationship of the photoluminescence emission spectra and the crystal structure will be discussed, as well as the possibility of the reduction of the Eu oxidation state. [1] G. Bellochi et al., Optics Express 20, 5501 (2012)

N.N.PI.33
17:00
Authors : Vytautas Stankus, Aleksandras Iljinas
Affiliations : Department of Physics, Kaunas University of Technology

Resume : ABO3-type perovskite are widely investigated because of their interesting applications in many fields. Oxides of this type display a wide spectrum of physical properties, such as ferroelectricity, piezoelectricity, semiconductivity, metallic conductivity, ferromagnetism, etc.; they are important in modern technology. BiFeO3 (BFO) has been considered as an important material for the development of multifunctional devices because of its distinctive ferroelectric, magnetic, piezoelectric, and optical properties. The BiFeO3 oxide thin films were deposited on platinized silicon substrate by reactive magnetron layer by layer deposition in O2 gas environment (p = 1.33 Pa) at various substrate temperature (400-700 oC). Multilayer system Pt/Ti/SiO2/Si was used as substrate with the thickness of Pt, TiO2 and SiO2 layer of 100 nm, 50 nm, and 1 µm, respectively. The deposition of lead titanate was realized using substrate periodic and parallel to cathodes motion over the magnetrons (layer by layer). Bi2O3 and Fe2O3 deposition rates were constant 18 nm/min and 14 nm/min respectively. The samples were analyzed using SEM (RAITH-e-LiNE, Raith GmbH). The crystallographic structure of thin films was investigated by XRD (Bruker D8 Advance) using monochromatic Cu Kα radiation with Bragg-Brentano geometry. Sawyer and Tower method for polarization–electric field (P-E) loop measurements was used for hysteresis loops measurements. The results show that the crystalline nature of BiFeO3 thin films strongly depends on the substrate material and the substrate temperature. The XRD patterns of deposited thin films at 400-650oC substrate temperatures are shown several peaks corresponding to BFO phase. The highest quality perovskite structure thin films were deposited at 550 oC substrate temperature using 10 nm thickness Ti seed layer. Seed layers increase nucleation centers and therefore the density of grains, crystallites and therefore the adhesion. The roughness of BiFeO3 thin films were less than 10 nm. The best results was got using Ti(10nm) seed layer, which let to form dense grained BFO thin film with small nanocrystal structure, good adhesion, remnant polarization (60 μC/cm2) and coercive field (140 kV/cm).

N.N.PI.34
17:00
Authors : N. Korsunska1, T. Stara1, Yu. Polishchuk, O. Kolomys1, K. Michailovska1, V. Strelchuk1, M. Kharchenko2, O. Gorban2, L. Khomenkova1
Affiliations : 1)V. Lashkaryov Institute of Semiconductor Physics, 45 Pr. Nauky 03028 Kyiv Ukraine; 2) O.O.Galkin Institute for Physics and Engineering, 72 R. Luxemburg str., Donetsk 83114, Ukraine

Resume : Light emitting ability of pure and Y-doped ZrO2 (Y-ZrO2) materials offer their photonic application. In this work the effect of Cu doping and phase transformation in (Y,Cu)-ZrO2 powders on their photoluminescence (PL) spectra was studied. The powders with 3mol% of Y and 1-8 mol% of Cu were produced by a co-precipitation technique from Zr, Y and/or Cu nitrates and calcined at Tc=500-1000°С for 2 h, and investigated by means of Raman scattering and PL methods. Raman scattering spectra revealed the t-ZrO2 phase only in all Y-ZrO2 powders. The (Y,Cu)-ZrO2 samples sintered at Tc=500-800°C also showed the presence of this phase predominantly, whereas the further Tc increase results in appearance of significant contribution of m-ZrO2 demonstrating the t-m phase transformation. This latter is dominant in codoped powders sintered at 1000°C. The higher Cu content in the powders, the higher Tc of t-m phase transition was observed. The analysis of PL spectra of the samples showed that along with two main PL components peaked at 550 and 640 nm observed for Y-ZrO2 samples, Cu incorporation stimulates an appearance of PL band peaked at ~515 nm. The PL intensity shows non-monotonous behavior with the Tc rise. Its increase up to the value of t-m transformation leads to the PL quenching, whereas the rise of m-ZrO2 phase contribution causes the PL enchancement, the 515-nm PL component increasing mainly. This PL behavior of codoped samples is discussed in terms of coloration centers formation.

N.N.PI.37
17:00
Authors : F. Dumas-Bouchiat1, C. Goldner-Constantinescu1, S. Quignon1, P. Marchet1, C. Champeaux1 M. Rammal2, L. Huitema2, A. Crunteanu2, D. Passerieux2, D. Cros2, T. Monédière2, V. Madrangeas2 L. Nidelcu3, L. Trupina3, G. Banciu3, M. Cernea3
Affiliations : 1SPCTS UMR 7315 CNRS/Université de Limoges, Centre Européen de la Céramique, 12 rue Atlantis, 87068 LIMOGES France 2XLIM UMR 6172 CNRS/Université de Limoges 123 Av. A. Thomas, 87060 LIMOGES Cedex France 3 NIMP, 077125 MAGURELE, ILFOV, Romania

Resume : New technologies for information and communication require integration of passives components of smaller size with increasing performances. In the case of compact antennas, one way to achieve this objective (1) is the integration of tunable capacitors (metal/ferroelectric/metal (MFM) or interdigitated (IDC)) using ferroelectric materials. Indeed, their tunability materials with an applied electrical bias, with convenient dielectric losses, as (Ba,Sr)TiO3 (BST) materials, could be an attractive solution (2,3). BST thin films are fabricated by Pulsed Laser Deposition (KrF =248 nm) on MgO(100) or on Iridium electrode on MgO(100). The influence of processing parameters on structural properties (orientation, grain size…) of BST is studied. The dielectric properties in the RF range (2-13GHz) are extracted from a combination of measurements using a resonant cavity method and electromagnetic simulations of the capacitors (4). The BST films present permittivity in the range 500-1300 with losses of about 7.10-2 at 12GHz and show an agility of 28% at 2GHz up to 40% at 11GHz. The design and performances of agile antennas integrating these tunable BST-films will be presented and discussed. (1) L. Huitema, Progress in compact antennas, Intech, 2014. (2) N. K. Pervez et al., Applied Physics Letters, 85, 4451-4453, 2004. (3) T. Delage et al., Thin Solid Films 453-454, 273-278, 2004. (4) P. Queffelec et al., J. Appl. Phys., 115, 024103, 2014.

N.N.PI.39
17:00
Authors : I. Fina[1,2], M. Gich[3], A. Morelli[1], F. Sánchez[3], M. Alexe[2], J. Gàzquez[3], J. Fontcuberta[3], A. Roig[3]
Affiliations : [1] Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), D-06120, Germany; [2] Department of Physics, University of Warwick, Coventry CV 4 7AL, United Kingdom; [3] Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra 08193, Spain

Resume : The quest for magnetoelectric multiferroics is driven by the promise of a novel generation of devices combining the best characteristics of ferromagnetic and ferroelectric materials. These cherished applications require materials displaying a substantial magnetization and electric polarization which are coupled and coexist well above room temperature. These properties are not commonly fullled found by in a single phase materials and candidates for thepropelling the development of these technologies are still sought required. In this contribution, we will report on epitaxial epsilon-Fe2O3 thin films grown by Pulsed Laser Deposition on (111) SrTiO3 and present recent data on its structural, magnetic and dielectric characterization. The films are ferromagnetic and ferroelectric at room temperature and display magnetization and polarization values at remanence of about 50 emu/cm3 and 1u C/cm2 with a long retention. A magnetocapacitive response has also been detected suggesting a sizeable coupling between both ferroic orders. The chemical simplicity of epsilon-Fe2O3 represents a major advantage to overcome the challenges of stoichiometry and phase purity control that might be cumbersome in all other known room-temperature multiferroics. [1] M. Gich, I. Fina, et al., Advanced Materials 26, 4645(2014).

N.N.PI.41
17:00
Authors : D. A. C. Albuquerque, J. R. R. Bortoleto, M. Chaves, , S. F. Durrant, J. H. D. da Silva, T. F. Smith
Affiliations : 1 São Paulo State University (UNESP) – Av.3 de Março 511, Sorocaba, SP, Brazil; 2 São Paulo State University (UNESP) – Av. Eng. Luiz Edmundo Carrijo Coube, Bauru, SP, Brazil; 3 São Paulo University (USP) – Rua do Matão, trav. R,187, São Paulo, SP, Brazil

Resume : Aluminum zinc oxide (AZO) has been used as transparent and conducting oxide film in solar cells and electrochromic devices. Also, AZO thin films have great potential for applications in flexible display technology. In this work, nucleation and final texture of ZnO:Al (5%at) polycrystalline films grown by reactive RF magnetron sputtering at temperatures lower than 250oC have been investigated. Surface morphology was measured with atomic force microscopy (XE-100, Park Instruments) operating in air. All AFM images of the films were analyzed using fractal and scaling concepts. The orientation and size of crystallites were estimated using X-ray diffraction (D/MAX-2100/PC, Rigaku). Optical transmittance was performed using Uv-Vis-NIR spectrometer (Lambda 750, Perkin Elmer) ranging from 190 nm to 3300 nm. The chemical composition and density of films were obtained by Rutherford backscattering spectroscopy (RBS) with 2.2 MeV He ions. Electrical resistivity was measured by the four-po int probe method. In order to study the growth evolution, different ZnO films with thickness ranging from 0 up to 1250 nm were deposited. Our results indicate the formation of an AZO amorphous layer during the early growth stages. The surface roughness is driven by non-local shadowing mechanism. Furthermore, depending on temperature, surface diffusion between planes and between grains are comparable and a polycrystalline film with a misalignment final texture is produced.

N.N.PI.42
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09:45
Authors : S. Iwahashi (1), S. F. Chichibu (1), K. Furusawa (1) , Y. Yamazaki (1), K. Kojima (1), A. Uedono (2)
Affiliations : IMRAM-Tohoku Univ. (1); IAP-Univ. Tsukuba (2)

Resume : Metalorganic vapor phase epitaxy and molecular beam epitaxy are exclusively used for fabricating semiconductor quantum structures, although they require large amounts of capital cost. Conversely, sputtering is a cost-effective approach for depositing large-area amorphous or polycrystalline thin films. We have been developing a novel epitaxial growth technique by combining the virtues of these technologies: helicon-wave-excited-plasma sputtering epitaxy (HWPSE) [Chichibu et al., JAP 91, 874 (2002)] so that large-area epitaxial growth can be realized in a simple system at low cost. In this presentation, HWPSE of reduced donor concentration Zn-polar (0001) ZnO homoepitaxial films exhibiting a step-and-terrace surface structure with the terrace width as wide as 0.85μm and a monolayer height of 0.26 nm will be demonstrated. Using a crystalline ZnO target prepared by the hydrothermal technique, instead of the target synthesized by the chemical vapor transport, residual concentrations of B, C, Cr, Li, and Si in the epilayers underran the detection limits of secondary-ion-mass spectrometry. Because the present target do not contain Ga or In, low temperature photoluminescence (PL) spectra were dominated by sharp emission peaks originating from the recombination of free excitons and excitons bound exclusively to a neutral Al, of which concentration was 2x10^16 cm-3. The full-width at half-maximum value of the near-band-edge emission at room temperature became as narrow as 65 meV

N.NV.3
11:15
Authors : I. Fina[1,2], X. Mart?[3,4], J.H. Lee[2], D. Preziosi[2], A. Quindeau[2], H. Deniz[2], D. Kriegner[5], M. Ziese[6], F. Bern[6], G. Apachitei[1], P. Ferrer[7], C. Nicklin[7], E. Pippel[2], Y.H. Kim[8], D. Hesse[2], M. Alexe[1]
Affiliations : [1] Department of Physics, University of Warwick, Coventry CV 4 7AL, United Kingdom. Mail: ignasifinamartinez@gmail.com; [2] Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Saale), Germany; [3] Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University; 12116 , Praha 2 , Czech Republic; [4] Centre d?Investigacions en Nanociencia I Nanotechnologia (CIN2) CSIC-ICN, Bellaterra 08193, Barcelona, Spain; [5] Department of Condensed Matter Physics, Faculty of Mathematics and, Physics, Charles University, CZ-121 16 Prague 2, Czech Republic; [6] Institute for Experimental Physics II, University of Leipzig, Linn?trasse 5, D-04103 Leipzig, Germany; [7] Diamond Light Source, Harwell Science and Innovation Campus, Chilton, Didcot OX11 0DE, United Kingdom; [8] Korea Research Institute of Standards and Science, Daejeon 305?304 , Republic of Korea.

Resume : In the field of multiferroic (MF) materials several systems have shown the coexistence of electric and magnetic order with coupling between them. However, direct evidences of spintronic functionalities in presence of magnetoelectric coupling are still not systematically reported. We present direct demonstration of spintronic functionalities: anisotropic magnetoresistance (AMR) and tunnel magnetoresistance (TMR) in several MF systems. We will focus on the occurrence of AMR at the ferroelectric domain walls of an archetypical MF, i.e. BiFeO3 (BFO), showing that BFO conductive domain walls display hysteretical AMR. This effect results from the ferromagnetic nature of domain walls magnetically coupled to the antiferromagnetic domains of BFO. [1] We have also studied a MF La1-xSrxMnO3 (LSMO)/ PZT epitaxial bilayer. We have observed that the electronic doping of LSMO is modified by the electric field generated by the adjacent ferroelectric, and that it produces significant changes on AMR stemming from the change on LSMO magnetic properties. [2] Focusing on TMR effects on MF structures, we have found that spin valve functionality naturally appears in a MF LSMO/PbTiO3/Co magnetic tunnel junction. This implies that the system shows memory functionality on top of the TMR effect, upgrading the junction performance. [3] [1] J. H. Lee, I. Fina, et al. Adv. Mat. 26, 7078 (2014). [2] D. Preziosi, I. Fina, et al. Phys. Rev. B 90, 125155 (2014). [3] A. Quindeau, I. Fina, et al. Submitted.

N.NVI.3
11:45
Authors : Martin Hoffmann, Victor N. Antonov, Lev V. Bekenov, Arthur Ernst, Waheed Adeagbo, Wolfram Hergert, Kalevi Kokko
Affiliations : Institute of Physics, Martin Luther University Halle-Wittenberg, German & Max Planck Institute of Microstructure Physics, Halle, Germany; Institute for Metal Physics, Kiev, Ukraine; Institute for Metal Physics, Kiev, Ukraine; Max Planck Institute of Microstructure Physics, Halle, Germany; Institute of Physics, Martin Luther University Halle-Wittenberg, German; Institute of Physics, Martin Luther University Halle-Wittenberg, German; Department of Physics and Astronomy, University of Turku, Finland & Turku University Centre for Materials and Surfaces (MatSurf), Finland;

Resume : The double perovskite Sr2FeMoO6 (SFMO) is one of the interesting compounds for spintronic applications due to the high Curie temperature (TC > 400 K) and the half-metallic character. We grew well ordered SFMO films of varying thicknesses on SrTiO3 with pulsed laser deposition and determined the lattice parameters and thereby the epitaxial strain of the films from the X-ray diffraction data. The TC and the saturation magnetization (Msat) were determined with a SQUID magnetometer. The experimental results show that in comparison with the bulk, TC and Msat of the films were strongly reduced (ΔTC=80K) and the changes coming from the imposed epitaxial strain of the substrate were not sufficient to explain these large changes alone. For a further microscopic understanding, we used first-principle calculations to systematically investigate the electronic and magnetic properties. The calculations confirm the small changes in TC due to the epitaxial strain. On the other hand, defects (anti-site swaps and oxygen vacancies) are very likely. Their formation energy is altered for different lattice constants and the simulation of TC showed larger changes. In addition, we simulated X-ray absorption spectra and compared them with former experimental results. A good agreement was only obtained by considering a contribution of Fe2 and oxygen vacancies. So, lattice defects represent a possible explanation for the experimentally observed discrepancies in the magnetic properties.

N.NVI.5
14:45
Authors : H. Makino1,2; H. Song1; S. Kishimoto3; J. Nomoto1; T. Yamamoto1
Affiliations : 1Res. Inst. of Kochi Univ. of Tech; 2Systems Engineering, Kochi Univ. of Tech.; 3Kochi National Coll. of Tech.

Resume : Ga-doped ZnO (GZO) is promising candidate as sensing materials for hydrogen sensor operated at low temperature. In semiconductor gas sensors, adsorption and desorption at surface or grain boundary have been considered as operation mechanisms. In this paper, we report characterization of surface and bulk chemical state of GZO films with focused on influences of thermal annealing. The GZO films were deposited by ion-plating with DC arc discharge under the oxygen gas flow rate of 5 (GZO5) and 25 sccm (GZO25), respectively. Considering gas sensing temperature, the films were annealed in nitrogen gas atmosphere. After the annealing, the carrier concentration increased in the GZO25, while it did not change in the GZO5. From the Zn 2p and O 1s spectra measured by surface sensitive soft x-ray photoemission spectroscopy, we only observed desorption of hydroxyl groups and other adsorbate species from surface by annealing in the both GZO films. On the other hand, in the Zn 2p spectra measured by bulk-sensitive hard x-ray photoemission spectroscopy, we observed clear change in the Zn 2p spectra corresponding to decrease of carrier concentration in the GZO25, and nearly no change in the GZO5. These observations are consistent with change of carrier concentration caused by the annealing. From detailed analysis on angle resolved photoelectron spectroscopy on the O 1s, it was suggested that the change of carrier concentration were caused by desorption of chemically adsorbed oxygen.

N.NVII.3
15:00
Authors : Gabriel Socol1, Sophie Le Caër2, Doina Craciun1, Aurelian C. Galca3, Catalin Martin4, Valentin Craciun1
Affiliations : 1National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania; 2Institut Rayonnement Matière de Saclay, France; 3National Institute for Materials Physics, Magurele, Romania; Ramapo College of New Jersey, NJ, USA

Resume : Amorphous oxide thin-film transistors (TFTs) have been extensively studied in the last decade due to their better properties compared to amorphous-silicon TFTs. They could be manufactured at low temperatures on inexpensive, light weight and flexible polymer substrates, opening the possibility for space applications. There have been very few studies about their performance and reliability under radiation. We deposited amorphous indium zinc oxide thin films having different In/(In+Zn) compositions by the pulsed laser deposition (PLD) technique. The deposited IZO films exhibited good optical properties in the visible and near infrared range, low resistivity and high mobility. After deposition, the films were submitted to gamma radiation from a 137Cs source up to a dose of 20 kGy (1 Gy = 1 J.kg-1) at a dose rate of 5 Gy/min. The experiments were performed under argon atmosphere and also under air for the sake of comparison. X-ray reflectivity and diffuse scattering investigations were performed to accurately measure the thickness and estimate changes induced by gamma radiation on the mass density and surface and interface roughness. Spectroscopic ellipsometry and optical reflectivity investigations were used to assess changes induced by the irradiation on the optical and electrical properties of the films. The results showed that amorphous films could tolerate higher doses than polycrystalline layers without a marked decrease of their properties.

N.NVII.4
16:45
Authors : Emile HAYE, Fabien CAPON, Silvère BARRAT
Affiliations : Institut Jean Lamour UMR 7198, Parc de Saurupt, FRANCE

Resume : Perovskite materials with ABO3 formula present interesting properties depending on their composition, and have been studied for their potential applications as gas sensors, fuel cells or catalyst. Perovskite ABO3 based on Rare Earth cation associated with 3d transition metal (A= La, Pr, Nd, Sm, and B=Co, Ni, Mn, Fe) can present thermochromic properties, it means a reversible change of optical and electrical properties with temperature. This transition, where a semiconducting behavior is observed at low temperature while metallic state is observed at high temperature, is directly dependent of the 3d element electronic structure, and the A cation size. The electronic structure of anion plays also a key role in structural and physical properties, and oxygen substitution by nitrogen can lead to modification of these properties. Due to higher energy of nitrogen 2p orbital, it gives thus an additional way to tune perovskite properties. In this work, several perovskites deposited by reactive magnetron sputtering are studied. Rare earth (RE= La, Pr, Nd, Sm) cobaltites (RECoO3) and Rare earth ferrite (REFeO3) films are deposited on (100) undoped Si single crystal and fused silica substrates, from two metallic targets RE and Fe or Co. The RE and Fe contents inside the growing films were controlled by the current applied to the targets. Oxygen or Oxygen/Nitrogen mixture is used as reactive atmosphere to form corresponding oxide or oxinitride. The chemical stoechiometry of the deposited material was checked by energy dispersive X-ray analyses. The amorphous films were then annealed to crystallize the perovskite, and the corresponding crystallized structure was checked by XRD measurements. Optical measurements were performed in UV, Visible and IR range (determined by UV-Visible and FTIR spectroscopy), and resistivity was determined by four probes methods at different temperatures (from 25°C up to 600°C), thanks to Linkam® heating device. This work presents the link between cation and anion elements and their direct influence on the perovskite properties.

N.NVIII.3
17:00
Authors : C. Hebert1.2, N. Jedrecy1.2, M. Nistor3, E. Millon4
Affiliations : 1Sorbonne Universites, UPMC Univ Paris 06, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris, France; 2CNRS, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris, France; 3National Institute for Lasers, Plasma and Radiation Physics, L22 P.O.Box MG-36, 77125 Bucharest, Romania; 4Univ. Orleans, UMR CNRS 7344, GREMI, 14 Rue Issoudun, F-45067 Orleans 2, France

Resume : Spinel zinc ferrite ZnxFe3-xO4 (0.1

N.N. PII.6
17:00
Authors : D. Louloudakis1,2*, D. Vernardou1, E. Spanakis3, M. Panagopoulou4, Y. Raptis4, G. Kiriakidis2,5, N. Katsarakis1,5,6, E. Koudoumas1,6
Affiliations : 1Center of Materials Technology & Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece; 2Department of Physics, University of Crete 711 00 Heraklion, Crete, Greece; 3Department of Materials Science & Technology, University of Crete 711 00 Heraklion, Crete, Greece; 4School of Applied Mathematical and Physical Sciences, National Technical University of Athens, GR 157 80, Zografou Campus, Athens, Greece; 5Institute of Electronic Structure & Laser, Foundation for Research & Technology- Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete, Greece; 6Department of Electrical Engineering, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece

Resume : Chemical vapor deposition (CVD) is a simple, low cost and easily transferred method to large scale for the growth of various deposition layers. In addition, deposition parameters such as the kind and the amount of precursors, deposition time and temperature, can simply be controlled. However, a small change in one of the above parameters can lead to different vanadium oxidation states with consequently different properties. In this paper, vanadium oxide coatings were fabricated using a chemical vapor deposition at atmospheric pressure (APCVD) on SnO2 pre-coated glass substrates using vanadyl (IV) acetylacetonate as vanadium precursor at 500 oC and O2, 2-propanol and ethanol as oxygen sources. The samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron Microscopy (SEM), UV-Vis-NIR spectroscopy measurements at temperatures below and above Tc, transmittance measurements as a function of temperature at an incident radiation of 1500 nm and cyclic voltammetry. The effect of oxygen source through the reactor on the properties of the samples is discussed.

N.N. PII.8
17:00
Authors : I.C. Vasiliu1, I. Ionita2, A. Matei3 , M.Elisa1, R. Iordanescu1, I. Feraru1, A. Emandi1
Affiliations : 1INOE 2000 - National Institute for Optoelectronics, 409 Atomistilor Str., Magurele RO-077125, Bucharest, Romania, icvasiliu@inoe.inoe.ro 2UB - University of Bucharest, 405 Atomistilor Str., Magurele RO-077125, Bucharest, Romania 3INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele, RO-077125 Bucharest, Romania

Resume : The demand for protection of various types of optical sensors from laser-beam pulses has resulted in the search for optical limiting devices that have the property of being transparent at low intensity of light (normal light), but no transparent towards high intensity (laser) light. Organic material that displays nonlinear optical (NLO) properties as reverse saturable absorption and two-photon absorption can be used for optical limiting with the advantage of a very fast response and self-activating, that is, there is no need for externally controlled switching to obtain optical limiting. On the other hand for device applications oxide thin films as host for organic NLO compounds offer the unique opportunity. A promising approach in the fabrication of such new thin films by low cost / easy use deposition methods for second-order nonlinear optics is sol-gel technique. The present paper reports on the sol-gel synthesis of some pyrazolone derivative doped SiO2-P2O5 smooth and homogenous films (Root mean square roughness (Rq) =1,3 nm ) using as precursors tetraethylorthosilicate (TEOS) and phosphoric acid (H3PO4). The structure of the deposited azo-derivatives doped thin films was examined by Fourier transform infrared spectroscopy, and atomic force microscopy and their optical properties by UV-VIS spectroscopy. The nonlinear optical efficiencies due to the interaction of the NLO-active chromophores with the inorganic matrix has a significant influence on the second harmonic generation capabilities that was measured using a femtosecond Ti:sapphire laser. The properties of the films were investigated and correlated with the concentration of the organic dopant and the thermal treatment temperature.

N.N. PII.9
17:00
Authors : Peep Uudeküll 1, Liis Seinberg 2, Joosep Link 2, Jekaterina Kozlova 1, Olesja Bondarenko 2, Kaja Kasemets 2, Anne Kahru 2, Raivo Stern 2, Tanel Tätte 1, Aile Tamm 1
Affiliations : 1 Institute of Physics, University of Tartu, Ravila 14c, EE-50411 Tartu, Estonia 2 National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn, Estonia

Resume : The synthesis and characterization of magnetic metal nanoparticles (NP) have received a broad attention of scientists because of their applications in magnetically guided therapies [1]. To prevent oxidation of highly reactive nanoscale metal particles, atomic layer deposition (ALD) of thin amorphous TiO2 film on their surface has been proposed [2]. In this work, we synthesized the NP by using a versatile, convenient, and nontoxic solvothermal method, using benzyl alcohol as the liquid phase (known as the benzyl alcohol method) and metal acetylacetonates as the source of metal. Process was carried out in order to prepare Fe, Co, Mn and Ni in form of metal or metal oxide NPs. Fe and Ni as magnetic particles (from 60 nm to 2000 nm and 300 nm to 500 nm in size, respectively) were selected out from the bunch of obtained materials in order to deposit a 10 nm thick TiO2 layer on their surface with ALD. Deposition was carried out from TiCl4 and H2O at 300°C. The characterization of NPs, done by using SEM, XRD, VSM-PPMS and EDX analysis, indicated that nanostructured Fe-oxide in form of Fe3O4 as well as pure nickel show up to 10% lower saturation magnetization than their coated counterparts. We propose the oxidation protected metal particles for medical use and plan to carry out their safety tests (in vitro toxicity assays) as a next step of our studies. 1. G.F. Goya et. al., MRS Bull. 39, 2014, 965-969 2. S.D. Standridge et, al., Langmuir 25, 2009, 2596-2600

N.N. PII.14
17:00
Authors : V. P. Tsikourkitoudi 1,2 G. C. Bourantas 3, P. N. Gavriliadis 4, G. Lolas 5, S. P. A. Bordas 3,6, T. Zhang 1
Affiliations : 1 Faculty of Science, Engineering and Computing, Kingston University London, SW15 3DW, United Kingdom; 2 Technological Centre LUREDERRA, Área Industrial Perguita, Calle A, no1, 31210, Los Arcos, Navarra, Spain; 3 Faculty of Science, Technology and Communication, University of Luxembourg, Campus Kirchberg, 6, rue Richard Coudenhove-Kalergi L-1359, Luxembourg; 4 Department of Naval Architecture and Marine Engineering, National Technical University of Athens, Heroon Polytechniou 9, GR-157 73 Zografos, Athens, Greece; 5 Center for Advancing Electronics Dresden, Technische Universität Dresden, 01062, Dresden, Germany; 6 School of Engineering, Cardiff University, The Parade, CF24 3AA Cardiff, United Kingdom

Resume : Lithium titanate (Li4Ti5O12, LTO) is a promising anode material for the next generation of lithium ion batteries. Its physical properties and morphology (which consequently affect its electrochemical performance) highly depend on its synthesis method. FSP is an attractive process for the controlled one-step synthesis of functional multicomponent oxides from low cost precursors1. During FSP the liquid precursor is sprayed and dispersed into the flame zone with the aid of an oxidizing gas, combusted and converted into nanoparticles through droplet evaporation, nucleation, sintering and agglomeration. The main aim of this study is to control the growth process of LTO in order to maintain the desired particle properties. LTO nanoparticles of different sizes are synthesized by variation of the FSP processing conditions and characterized accordingly. By varying the O2 dispersion gas flow rate (20-50l/min), LTO nanoparticles’ size decreases from 21 to 14nm due to decrease of droplet concentration in the flame. However, as the interaction of the aforementioned physical processes is hard to investigate only by experiments2, numerical simulations based upon computational fluid dynamics techniques are implemented in order to examine the process steps and the effect of the FSP processing conditions on the particle size. 1 H.Torabmostaedi, T.Zhang, Chem. Eng. Res. Des. 92, 2470, 2014. 2 A.J.Gröhn, S.E.Pratsinis, A.Sánchez-Ferrer, R.Mezzenga, K.Wegner, Ind. Eng. Chem. Res. 53, 10734, 2014

N.N. PII.16
17:00
Authors : M. Nistor, F.Gherendi, N.B.Mandache
Affiliations : National Institute for Lasers, Plasma and Radiation Physics (NILPRP), L22 P.O. Box. MG-36, 77125 Bucharest-Magurele, Romania

Resume : Owing to their specific optical and electronic properties, ZnO thin films offer a promising alternative to indium tin oxide for applications in photovoltaics and transparent electronics. ZnO thin films were grown at room temperature by pulsed electron beam deposition under different growth parameters. Dense and smooth films are formed on SiO2 / Si wafer, large area glass or flexible substrates, and their stoichiometry and physical properties were controlled by the deposition geometry, nature and pressure of the gas during deposition. Electrical and optical properties of these large area ZnO thin films were mapped in each point by four point probes, optical transmittance in UV-visible-near infrared region and photoluminescence spectroscopy. Large variations of the O/Zn ratio were evidenced over a range of several centimeters thus allowing for the above mentioned measurements to be performed for various compositions. Transparent ZnO thin films show tunable resistivity and carrier density up to few orders of magnitude, making them interesting for low-cost transparent electronics, such as single step fabrication of thin film transistors or resistive random access memory devices.

N.N. PII.17
17:00
Authors : Georges Al Makdessi, Malek Tabbal
Affiliations : Department of Physics, American University of Beirut, Bliss St. P.O. Box:11-0236, Beirut, Lebanon 1107 2020

Resume : The aim of this work is to investigate the expansion of an oxygen low-pressure microwave plasma. By measuring electron density and electron temperature, using Langmuir probe, we search the optimal parameters such as pressure and microwave power, to use in titanium and manganese films oxidation and surface modification. Titanium and manganese films were grown on Si (100) substrates by sputtering of a metallic titanium target and Pulsed Laser Deposition of a manganese target respectively. The effect of operating parameters such as substrate temperature, chamber pressure and plasma activation on the oxidation of these films was studied using GIXRD technique. We find that the electron density increases with the injected power into the plasma while the electron temperature keeps a constant value. In addition, the two quantities show a decrease when the plasma expands in the reactor. Moreover, electron density shows maximum value at low pressure (5mTorr – 20 mTorr) and high microwave power (300 – 400W) which led us to work at these conditions in the remote plasma assisted oxidation of titanium and manganese films. At a substrate temperature of 500 C and without plasma activation, we got a multiphase titanium oxide film with a predominantly TiO2 anatase phase. With plasma activation at this temperature, a pure phase of anatase was formed. In parallel, the exposure of manganese films to oxygen remote plasma led to the formation of a mixture of two phases of manganese dioxide (Ramsdellite and Pyrolusite), while the exposure to an oxygen gas without plasma activation led to the formation of Hausmanite (Mn3O4).

N.N. PII.21
17:00
Authors : Z.R. Kudrynskyi (1,2), V.M. Katerynchuk (2), M.Z. Kovalyuk (2), V.V. Khomyak (3), V.V. Netyaga (2), B.V. Kushnir (2)
Affiliations : (1) School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD, United Kingdom; (2) Institute for Problems of Materials Science, The National Academy of Sciences of Ukraine, Chernivtsi Department, Chernivtsi 58001, Ukraine, (e-mail: kudrynskyi [at] gmail.com); (3) Chernivtsi National University, Chernivtsi 58012, Ukraine

Resume : The van der Waals surfaces (0001) of InSe and GaSe layered semiconductors were for the first time used as substrates for growing Zn0.5Cd0.5O oxide films. It is shown that surface morphologies of the nanostructured oxide films deposited by means of radio-frequency magnetron sputtering onto InSe and GaSe substrates are different. The n-Zn0.5Cd0.5O/p-InSe heterojunctions showed diode-like behaviour. The atomic force microscopy characterization of the oxide films revealed that the nanostructures have domelike shapes and are distributed uniformly over the surface. Their lateral density is relatively high (~10^10 cm^-2) and they are the centres of light scattering. It was established that the nanostructurization of the oxide surface results in emergence of an additional photosensitivity band of the heterojunctions in infra-red region. The oxide films under investigation have defects caused by mechanical strain at the heterointerface. It was revealed that these defects induce shunt currents of the heterojunctions. We demonstrated that vacuum annealing of the samples can be successfully used to decrease the influence of the shunt currents. The changes in electrical properties were investigated by analyzing temperature and frequency dependences of current-voltage and capacitance-voltage characteristics, respectively. In addition, we established that vacuum annealing affects the band-structure of Zn0.5Cd0.5O and the band-gap-energy can be tuned by a value in the range of ~0.14 eV.

N.N. PII.25
17:00
Authors : H. L. Meyerheim (1), A. Ernst (1), K. Mohseni (1), C. Tusche (1), W. A. Adeagbo (2), I. V. Maznichenko (2), W. Hergert (2), G. R. Castro (3), J. Rubio-Zuazo (3), A. Morgante (4), N. Jedrecy (5), I. Mertig (2), and J. Kirschner (1,2)
Affiliations : (1) Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany (2) Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany (3) ESRF, B.P. 220, F-38043 Grenoble Cedex, France (4) TASC-INFM National Laboratory, I-34012 Basovizza, Italy (5) Institut des Nano Sciences de Paris, UPMC-Sorbonne Universites, CNRS-UMR7588, 75005 Paris, France

Resume : Using surface x-ray diffraction in combination with ab-initio calculations we have studied the atomic structure of ultra thin ZnO films deposited on Fe(110). In contrast to expectation that ZnO adopts the "graphitic" hexagonal Boron-nitride structure the Wurtzite (WZ) structure is observed. Its formation is related to oxygen impurities in Fe(110) hollow sites inducing an anisotropic charge redistribution within the film which is characterized by a metallic surface. Our results provide a deeper understanding of depolarization mechanisms in ultra thin polar films at the atomic scale.

N.N. PII.26
17:00
Authors : Albert Juma, Abayomi Oluwabi, Ilona Oja Acik, Malle Krunks
Affiliations : Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia

Resume : Chemical spray pyrolysis (CSP) is a solution based deposition method that allows precursors to be mixed in varied ratios before deposition giving a wider degree of freedom in doping thin films for different applications. Doping TiO2 with zirconium improves the gate dielectric properties and its stability with a silicon substrate for metal-oxide-semiconductor based technologies. Zr-TiO2 films with different Zr concentrations (0 ? 40 mol%) were deposited at 450 oC onto quartz and Si substrates by CSP; followed by annealing at temperatures between 500 and 900 oC. The structural, morphological, optical and electrical properties of sprayed Zr-TiO2 films were studied. As-deposited Zr-TiO2 films showed an increase in smoothness and a decrease in the thickness, while the optical band gap (Eg) increased from 3.1 to 3.4 eV with increasing Zr amount. As-deposited TiO2 films exhibited anatase phase while the Zr-TiO2 samples were amorphous and anatase structure formed by annealing at 500 oC. Upon annealing at 600 oC, the mean crystallite sizes of Zr-TiO2 remain between 28 and 22 nm while the Eg increased to 3.4 eV irrespective of the Zr amount. Zr-TiO2 films annealed at 900 oC showed a mixture of anatase and rutile phases and decrease in Eg from 3.2 to 3.0 eV with increasing the Zr amount. The electrical properties of Zr-TiO2 were investigated in the metal-oxide-metal configuration, showing a strong dependence on the doping level.

N.N. PII.31
17:00
Authors : Kazbek Baktybekov, Aliya Baratova
Affiliations : U.M. Sultangazin Research Space Institute, Munaitpassov str. 3, 010008, Astana, Kazakhstan; L.N. Gumilyov Eurasian National University, Kazhymukan str. 13, 010008, Astana, Kazakhstan

Resume : Research of external action influence processes on the evolution of materials structures is one of the fundamental tasks with important applied significance. There are nonlinear processes in real systems. One of the perspective methods for description of such structures is the method of fractal analysis. The calculations of fractal parameters based on the geometric characteristics of the system, therefore spatial pictures of investigated structures can be obtained by the computer modeling of the nonlinear processes by the usage of cellular automata. The structure of solid describes its physical and chemical properties, any changes in material structure affect its mechanical, optical, electrical and other properties. In this work the influence of fractality of clusters forming on the heterogeneous surface of silicium oxide SiO2 on the photophysical processes are studied. General information about photoprocesses mechanisms are obtained based on model system investigation, for example, luminescent dye molecules applying on a solid surface. The components of system were organic dye Bengal Rose (BR) and aromatic Hydrocarbon Anthracene (An). Dye molecules are sorbed from spirit solution on the surface of SiO2 adding An dissolved in hexane. After laser irradiation electronic subsystem of BR molecules is exciting, particles of BR become donors of triplet energy and molecules An become acceptors. As a result of donor-acceptor interaction annihilation delayed fluorescence (ADF) is observed. The methods of computer modeling and multifractal analysis are used for study of the change of two-component system properties. The character of luminescence kinetics on the SiO2 surface depends on the interacting particles distribution at the initial moment of time. At the modeling of energy transfer processes confirmed that the multifractal structure can be formed as a result of accidental chaotic structure destruction. The phenomenon of ?burning out? of chaos occurs at accidental chaotic distribution of reagents molecules on the SiO2 at initial moment of time. The analysis of experimental results of kinetic processes on the SiO2 surface based on the multifractal formalism allows to establish the correlations between fractal properties of system and efficiency of electron excitation energy transfer. The ratio of the reagents molecules concentrations and the temperature of SiO2 surface are control parameters of processes occurring in the system. In the region of low temperatures the system tends to maintain its multifractal parameters independently from the concentration of donors and acceptors. The increase of the matrix temperature leads to loss of the system stability, to the change of the mechanism of energy transfer.

N.N. PII.34
17:00
Authors : E.A. Kotomin, M.M. Kuklja, D. Fuks, Yu. A. Mastrikov, J. Maier
Affiliations : Max Planck Institute for Solid State Research,Stuttgart, Germany, Institute for Solid State Physics, University of Latvia, Univ. Maryland, College Park, USA Ben Gurion University, Beer Sheva, Israel

Resume : Among advanced materials for clean energy, non-stoichiometric BaxSr1−xCo1−yFeyO3−δ (BSCF) and LaxSr1−xCo1−yFeyO3−δ (LSCF) are considered as promising materials for cathodes in solid oxide fuel cells (SOFC) and oxygen permeation membranes. BSCF exhibits the best oxygen exchange performance among similar materials, mixed ionic and electronic conductivity, high oxygen vacancy concentration, and low diffusion activation barrier, which largely define the oxygen reduction kinetics. However, it tends to decompose at low temperatures into a mixture of cubic and hexagonal perovskite phases, which strongly affects its practical applications. To understand the mechanism(s) of this unwanted process, the first principles quantum mechanical calculations of BSCF and LSCF crystals with different non-stoichiometry were performed and possible decomposition scenarios were studied. It is shown that formation energies of oxygen vacancies in the cubic and hexagonal phases of BSCF differ considerably and also behave in quite different ways depending on non-stoichiometry; in fact, it is the oxygen non-stoichiometry that makes the cubic phase more stable than the hexagonal phase. In comparison, LSCF is shown to be much more stable with respect to both the phase transformation and phase decomposition. The first principles calculations are accompanied with a thermodynamic analysis of the conditions under which a cubic phase is stable, in good agreement with experimental data.

N.N. PII.35
17:00
Authors : O. Benabdallah1, F. Cherkaoui El Moursli1*, Z.Edfouf 2, F.Hajji1 , E.B. Benameur3 and M. Abd-Lefdil3
Affiliations : 1 Laboratoire des Matériaux, Nanotechnologies et Environnement, Department of chemistry, University of Mohammed V, Faculty of Science, Rabat-Morocco; 2Morrocan foundation for Advanced Science, Innovation and Research MAScIR, Rabat, Morocco; 3Laboratory of Materials Physics, University of Mohammed V, Faculty of Science, Rabat-Morocco;

Resume : Zinc oxide has various interesting applications in many different fields, such as diodes, biosensors and transparent conducting film destined for solar-cell devices. However, its properties and applications are crucially dependent on size, orientation, morphology, aspect ratio and even the nanowire density. The effect on the structural quality of transition metals doping semiconductors is of considerable importance. In this work, we report the direct growth of Zn1−xFexO thin films (0.00≤x≤0.30) by single step electrodeposition method on ITO glass substrates. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for structural and morphological characterisations. X-ray diffractions reveals hexagonal würtzite structure with light shift of peaks according to the iron concentration, probably due to the insertion of the iron in the crystalline structure. All SEM micrographs show Zn1−xFexO nanowires perpendicular to the substrate.

N.N. PII.36
17:00
Authors : L. Khomenkova, V.I. Kushnirenko, M.M. Osipyonok, O.F. Syngaivsky, G.S. Pekar, K.A. Avramenko, V.V. Strelchuk, Yu.O. Polishchuk, V.P. Kladko, L.V. Borkovska
Affiliations : V. Lashkarev Institute of Semiconductor Physics, NAS of Ukraine, Pr. Nauki 45, 03028 Kiev, Ukraine

Resume : Zinc oxide is considered as a promising conductive oxide for photovoltaic and photonic applications due to its wide bandgap, mechanical stability and intense UV and green-orange emission. At the same time, the doping of ZnO with rare-earth (RE) ions offers fine monitoring light absorbing and emitting properties of the materials in required spectral range. In this work, screen-printed ZnO films doped with Sm3+ and/or Ho3+ ions were studied by means of photoluminescence (PL), Raman scattering and X-ray diffraction methods versus sintering conditions and doping level. All the films were found to be polycrystalline of a wurtzite structure. The increase of sintering temperature caused the enlargement of ZnO grains. The films sintered at temperatures below 700°C showed the UV emission only, whereas the films fabricated at higher temperatures also demonstrate the visible (540-600 nm) defect-related PL band. The doping of ZnO films with Sm ions resulted in broadening of the defect-related PL band towards the red spectral range, whereas the doping with Ho ions stimulated its widening towards the blue spectral range. Simultaneous codoping with both these ions caused the quenching of the UV and “native” visible PL bands as well as an enhancement of Sm3+ - and Ho3+ - related emission. The effect of RE doping on PL and PL excitation spectra is discussed in terms of energy transfer from ZnO host to RE ions as well as the formation of RE complexes.

N.N. PII.37
17:00
Authors : Petr Novák, Pavol Šutta, Marie Netrvalová
Affiliations : New Technologies - Research Centre, University of West Bohemia

Resume : Sputtered ZnO thin films mostly exhibit a strong preferred orientation of crystallites in the [001] direction perpendicular to the substrate surface (c-axis orientation). The preferred orientation of crystallites in the [100] direction (a-axis orientation) is obtained when the sufficient substrate voltage is applied during the deposition. Nevertheless, ions accelerated by voltage of tens or hundreds Volts damage the growing film and thus the post-deposition annealing is needed. We report about structural analysis of sputtered a-axis ZnO films annealed up to 900°C. The film structure was primarily observed by X-Ray Diffractometr equiped with high temperature vacuum chamber. We focus on the effect of the annealing temperature on the size, quality and preferred orientation of crystallites. We found that, while at up to 500°C the ratio between a-axis and c-axis phase is almost constant and only the structure is enhanced, at temperature higher then 500°C transformation from a-axis to c- axis orientation occurs.

N.N. PII.41
17:00
Authors : Eran Mishuk, Igor Lubomirsky
Affiliations : Department of Materials and Interfaces; Weizmann Institute of Science

Resume : Gd-doped ceria (GDC), one of the most studied oxygen ion conductors, was recently shown to exhibit electrostriction of 6.5?10-18 [m2/V2]. GDC is completely inert with respect to Si, which makes it very attractive for integrated MEMS applications. Using only Si-compatible processes, we fabricated large area (3-4 mm2) self-supported films (300-500 nm) of GDC with top and bottom Al contacts. We have developed a simple process to achieve complete strain relaxation in the GDC films, which permitted fine control of the buckling type and mode in the self-supported structures. Application of alternating voltage (AV) induces electromechanical response at the double frequency, which is typical for electrostriction. The amplitude of the vertical displacement is a few ?m and, surprisingly, the response persists till at least 1 MHz. Applying 2.5 AV (50 kV/cm) @ 100 kHz for a period of 17 hour (~6?109 cycles) does not cause to detectable degradation or fatigue. Using a proximity sensor, we determined that the amplitude of the displacement at the 2nd harmonic is linearly proportional to the applied electric field squared at least till 200kV/cm. This implies that the saturation field for GDC is above this value. Our results strongly suggest that GDC is a very promising material for electromechanical actuation in MEMS, in particular for mechanical switches and tunable capacitors.

N.N. PII.42
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Piezoelectric, thermoelectric, thermochromic, photoelectric and photonic applications (II) : N. Jedrecy, R. J. Gaboriaud
10:30
Authors : Francesco Scotognella, Alessandro Chiasera, Luigino Criante, Stefano Varas, Giuseppe Della Valle, Roberta Ramponi, Maurizio Ferrari
Affiliations : Francesco Scotognella1,2, Alessandro Chiasera3, Luigino Criante2, Stefano Varas3, Giuseppe Della Valle1, Roberta Ramponi1, Maurizio Ferrari3 1 Politecnico di Milano, Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie CNR, Piazza Leonardo da Vinci 32, 20133 Milano 2 Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133, Milan, Italy 3 CNR-IFN CSMFO Lab, Via alla Cascata 56/C, Povo, 38123 Trento, Italy

Resume : Disordered materials (with modulation of the refractive index comparable with wavelength of light) are deeply studied in order to achieve a better understanding of light transport in photonic media. Here we study the light transmission properties of one dimensional photonic structures in which the disorder is due to a random variation of the layer thickness. The photonic structures, made by silicon dioxide and titanium dioxide, have been fabricated by radio-frequency sputtering and characterized by spectrophotometry and electron microscopy. The light transmission properties of the disordered structure has been simulated by taking into account the dielectric constant dispersion of silicon dioxide and titanium dioxide, resulting in a very good agreement between the simulations and the experimental data. With respect to a periodic photonic crystal, the transmission of the photonic structure, in the range 300 – 1200 nm, is significantly lower [1]. Such study envisages the use of disordered one dimensional photonic structures for the modelization and realization of broad band filters. [1] A. Chiasera, F. Scotognella, L. Criante, S. Varas, G. Della Valle, R. Ramponi, M. Ferrari, Science of Advanced Materials, DOI: 10.1166/sam.2015.2249

N.NX.1
10:45
Authors : A. Stolz (1), A. Melhem (1), I. Petsagourakis (2), A. Petit (1), G. Fleury (2), G. Hadziioannou (2), G. Guegan (3), C. Boulmer-Leborgne (1), N. Semmar (1)
Affiliations : 1) GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2, France ; 2) Laboratoire de Chimie des Polymères Organiques, Université de Bordeaux – CNRS UMR 5629 – ENSCPB, Pessac Cedex, France ; 3) ST-Microelectronics, 37071 Tours Cedex 2, France

Resume : For years, materials are competing for the best thermoelectric properties through the enhancement of the figure of merit ZT. After metals and semiconductors, oxides and polymers are today in the front. In the same time, the way to evaluate the ZT property is often a problem because of the plural techniques and systems of measurement. The last development in the laboratory consists in a complete setup for the simultaneous evaluation of the Seebeck coefficient, electrical and thermal properties of the thermoelectric material, that we call ZT-meter. With this microscale device, we performed a deeply analysis of the thermoelectric behaviour of concerned materials. Evolving in a national project, called Tours2015, we are actually studying different sputtered PEDOT-Tos polymer thin films deposited on silicon, in order to correlate the growth parameters with the thermoelectric properties. With ZT values expected above 0.2, these materials could be serious candidates to be used later on as a new micro-source of energy.

N.NX.2
11:00
Authors : R. Moalla1, Q. Liu1, J. M. Vila-Fungueiriño2, A. Carretero-Genevrier1, B. Rivas-Murias2, G. Saint-Girons1, B. Vilquin1, N. Baboux3, G. Sebald4, C. Dubourdieu1, R. Bachelet1
Affiliations : 1 INL-CNRS, Ecole Centrale de Lyon, Ecully, France; 2 CIQUS, Campus Vida, USC, 15782-Santiago de Compostela, Galicia, Spain; 3 INL-CNRS, INSA de Lyon, Villeurbanne, France; 4 LGEF, INSA de Lyon, Villeurbanne, France

Resume : Due to the waste heat in ever more compact microelectronic devices, the harvesting of thermal energy has become interesting for self-powering small devices. Pyroelectric materials, which couple a change in temperature to a change in electrical polarization, can be used for the conversion of the thermal energy to an electric energy [1]. According to recent reports, single-crystalline pyroelectric films should provide an enhanced conversion energy efficiency with respect to bulk or polycrystalline materials [2]. Here, we show the monolithic integration of flat single-crystalline pyroelectric complex oxides (Ba1-xSrxTiO3 and PbZr1-xTixO3) on silicon via a thin SrTiO3 buffer layer grown by molecular beam epitaxy. In order to obtain a MIM heterostructure, an epitaxial bottom electrode (SrRuO3 or La0.7Sr0.3MnO3 layer) is used between the buffer layer and the pyroelectric film. Ferroelectric hysteresis loops at different temperatures give pyroelectric coefficients slightly higher than the bulk value (~400 µC.m-2.K-1 for PbZr0.52Ti0.48O3), and provide an estimation of the harvested pyroelectric energy (~50 mJ.cm-3.cycle-1). Effects of the different structures and compositions on lattice parameters, remnant polarization and pyroelectric coefficients will be discussed. The pyroelectric efficiency of single-crystalline films will be also compared to that of poly-crystalline ones. [1] S.B. Lang, Phys. Today 58, 31 (2005) [2] G. Sebald et al., Smart Mater. Struct. 18, 125006 (2009)

N.NX.3
11:15
Authors : Xinqiang Pan,1 Yao Shuai,1 Wenbo Luo,1 Huizhong Zeng,1 Ping Zhang,1 Chuangui Wu,1 Wanli Zhang,1 Heidemarie Schmidt2
Affiliations : 1. State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China; 2. Technische Universität Chemnitz, Department of Materials for Nanoelectronics, Faculty of Electrical Engineering and Information Technology, Chemnitz 09126, Germany

Resume : Resistive switching has been intensively investigated in oxide thin films, and it has been proved that oxygen vacancies (OVs) play important roles in the switching. However, OVs are always inevitably introduced into the oxide thin films during the deposition. That raises challenges in terms of the precise control of switching properties. Moreover, the coexistence of grain and grain boundaries in the polycrystalline oxide thin films grown on metal bottom electrodes makes it complicated to explore the transport behavior during the switching, which remains a large obstacle to understand the fundamental mechanism of the resistive switching. In the present work, ion-exfoliated single crystalline LiNbO3 (LNO) thin films with a thickness of 600 nm was bonded to Pt/SiO2/LNO substrates, and circular Au top electrode was sputtered to form Au/LNO/Pt capacitor structures. PFM results indicate that the thin film has a single domain structure without any domain boundaries or grain boundaries. The pristine LNO thin film shows high resistivity of Giga ohm, and no I-V hysteresis has been observed. However, after a vacuum annealing with a pressure of 1×10-3 Pa for 3 hours a forming step has been observed at a voltage of +24 V, and the thin film shows resistive switching behavior in the subsequent voltage cycles. This can be ascribed to the oxygen vacancies generated by annealing, which form conductive filaments in the LNO thin film. This work excludes the influence of randomly introduced OVs by traditional thin films deposition techniques, which benefits to a better control of the filaments formation and to a deep understand of the underline mechanism of the resistive switching in oxide thin films in the future work.

N.NX.4
14:30
Authors : S. Schamm-Chardon1,3, C. Magen2,3, L. Mazet4, R. Cours1, R. Bachelet4, G. Saint-Girons4, M. H?tch1,3, and C. Dubourdieu4
Affiliations : 1- CEMES-CNRS, Universit? de Toulouse, 31055 Toulouse, France 2- LMA-INA, Universidad de Zaragoza and Fundaci?n ARAID, 50018 Zaragoza, Spain 3- Transpyrenean Associated Laboratory for Electron Microscopy, CEMES?INA, CNRS?University of Zaragoza, Spain 4- INL, UMR CNRS 5270, Ecole Centrale de Lyon, 69134 Ecully, France

Resume : Ferroelectric oxides integrated on semiconductor substrates are of particular interest for various silicon-based electronic and photonic devices. Among them, the perovskite BaTiO3 is an attractive candidate for integrated photonics and low power logic devices. The control of the crystalline orientation of the ferroelectric tetragonal cell (c- versus a-axis orientation) as a function of the processing parameters is a key issue. In order to support the MBE growth strategy on SrTiO3-buffered Si of epitaxial BaTiO3 thin films with the desired orientation, high-resolution transmission electron microscopy (HRTEM) and high angle annular dark-field (HAADF) atomic structure images of various films were acquired and treated quantitatively using geometric phase analysis. Different deposition conditions were investigated (temperature, oxygen pressure, annealing). In this work, maps of the strain in the BaTiO3 films with respect to the Si substrate are determined at the nanometric scale (1-2nm) to evidence the local tetragonality (orientation and c/a ratio) of the BaTiO3 films. Correlations with the local cation composition are also proposed on the basis of electron energy loss spectroscopy (EELS) performed at the atomic scale. HRTEM work is performed on an image corrected Hitachi HF3300S microscope (I2TEM-Toulouse) and HAADF-EELS on a FEI Titan Low-Base 60-300 (Zaragoza).

N.NXI.3
15:00
Authors : D.Aureau1, A.Fouchet2, B. Bérini², Yves Dumont²,M.Bouttemy1,J.Vigneron1, N. Keller², A.Etcheberry1,
Affiliations : 1 Institut Lavoisier, UMR 8180 CNRS-UVSQ, Versailles, France 2 Groupe d’Étude de la Matière Condensée (GEMaC) UMR 8635 CNRS-UVSQ, Versailles, France.

Resume : Chemical characterization of surface and interface are crucial in materials science in order to understand the underlying physical properties. This is particularly true for strongly correlated electron systems like perovskite based materials where electronic correlations, structure, strain, intermixing, oxygen deficiency, surface reconstructions, are the means to control the properties of oxide thin films and heterostructures. XPS spectroscopy gives information about the chemical composition and the chemical environment of the atoms situated at surfaces and is a direct measurement of band offsets. Nevertheless , surface contaminants (water, adsorbed molecules) at the surface could provide a non-negligible contribution which modifies the analysis. In order to obtain clean surface, ion bombardment is used to clean and profile the surfaces. Nevertheless, the traditional ion etching with mono-atomic argon ions tends to modify the materials, challenging the analysis. We will present a new method for surface cleaning and profiling with cluster ion gun where the energy per atom is much less important. Consequently, this last etching appears to be much more gentle for any surfaces and doesn’t seem to change binding energies of the elements. The capacity to remove only the carbon contamination and then to control a progressive etching atoms by atoms is really promising to investigate various ultrathin films. First results based on model system based on SrTiO3 will be presented.

N.NXI.5
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09:15
Authors : J. Lopez-Sanchez(1), A. Serrano(2), M. Abuin(1,3), A. del Campo(2), J. de la Figuera(4), J.F. Marco(4), N. Carmona(1), O. Rodriguez de la Fuente(1)
Affiliations : (1) Dpto. de Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid; (2) Instituto de Ceramica y Vidrio, CSIC, 28049 Madrid; (3) CEI Campus Moncloa, UCM-UPM, 28040 Madrid; (4) Instituto de Quimica-Fisica "Rocasolano", CSIC, 28006 Madrid

Resume : The study of epsilon-Fe2O3 nanoparticles has aroused significant attention in recent years due to their promising properties such as giant coercive field (around 2T at room temperature), magneto-resistance or millimeter wave ferromagnetic resonance (FMR) [1]. Thus, epsilon-Fe2O3 nanoparticles are good candidates for the development of applications in fields as electronics, RF devices, hydrogen production [2] or new magnetic materials. In the present work we describe different synthesis routes of epsilon-Fe2O3 particles embedded in SiO2 films on Si(100) by an easy one-pot sol-gel method. We were able to modify the size and morphology thanks to addition of Barium nitrate, CTAB and Glycerol. Also, a Raman spectrum of a single epsilon-Fe2O3 nanoparticle without additional contributions from other iron oxides phases is presented for the first time. Moreover, low-temperature Raman study and output laser dependence have been performed in the range from 80 K to 600 K, observing anomalies in the intensity, bandwidth and band position when undergoing a ferromagnetic - paramagnetic transition located around 500 K. References [1] L. Machala, J. Tucek, and R. Zboril, Chem. Mater., 23, 3255?3272 (2011). [2] G. Carraro, C. Maccato, A. Gasparotto, T. Montini, S. Turner, O. I. Lebedev, V. Gombac, G. Adami, G. Van Tendeloo, D. Barreca, and P. Fornasiero, Adv. Funct. Mater. 24, 372?378, (2014)

N.N. XII.2
09:30
Authors : Dr Steve Dunn
Affiliations : Materials Research Institute, School of Engineering and Materials Science, Queen Mary University of London

Resume : In the last 10 years there has been growing interest in investigating the impact of non-centrosymmetry of piezo or ferroelectric materials for energy harvesting devices. The range of devices that are being investigated include those that can convert kinetic energy into electrical energy and the conversion of sunlight into fuels, known as solar fuels, or produce electrical energy such as in a photovoltaic device. The fundamental principle and area of interest, behind these energy conversion processes are related to the breaking of crystal symmetry that is found in a piezo or ferroelectric material. This breaking of the crystal symmetry intimately influences the physical properties within the material and leads to some very specific behaviour. In this talk I will show how the domain structure of a ferroelectric material effectively separates photoinduced carriers. This leads to regio-specific photochemistry where oxidation and reduction occur on predefined areas of the photocatalyst surface, separated by tens to hundreds of nanometres. We will then discuss how the dipole of the ferroelectric crystal lattice can be used to produce enhanced photocatalytic efficiency and how these dipoles can retard the recombination of photoinduced carriers. We have recently measured carrier lifetimes in BaTiO3 using transient absorption spectroscopy at 1-2 seconds without any external applied field, which exceeds values for traditional semiconductors under a strong applied electric field. The same fundamental phenomena is responsible for the 50% increase in power conversion efficiency in a ZnO based photovoltaic device when music is played and also enables us to effectively convert vibration into an electrical output. I’ll end by drawing a picture of how the breaking of crystal symmetry may influence energy conversion in the future.

N.N. XII.3
10:45
Authors : Aline Fluri, Daniele Pergolesi, Alexander Wokaun, Thomas Lippert
Affiliations : Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland

Resume : The influence of the strain on the oxygen-ion conductivity is investigated for ways to enhance the ionic conduction. Within the currently most accepted scenario, tensile strain is expected to lead to a decrease in the activation energy. Crystalline thin films are used as model systems to evaluate this effect, but reports are highly controversial. Doped ceria is a typical oxygen ion-conductor used as electrolyte in solid oxide fuel cells. Pulsed laser deposition allows the very controlled growth of epitaxial films. Tensile strain is induced in 15% samarium doped ceria by using a growth platform which provides a lattice mismatch of 1.4% and which is also suitable for electrical characterisations. This platform consists of a buffer layer of SrTiO3 on BaZrO3 on a MgO substrate. A Multi-beam Optical Stress Sensor is employed as a valuable tool to monitor the stress in situ via the substrate curvature during growth of such films. Simultaneously, the growth mode is monitored with Reflective High Energy Electron Diffraction. This so far unique combination can lead to a better understanding of the stress evolution during the growth. The strain is characterised additionally ex situ with x-ray diffraction and the tensile strain values are in agreement with the in situ stress measurement. Electrical characterisations of strained and relaxed films will be presented and the observed stress evolution will be compared with established models for thin films.

N.N. XIII.2
11:15
Authors : Y. Wang1, J. F. Pierson1, J. Ghanbaja1, S. Bruyère1, D. Horwat1, F. Soldera2, F. Mücklich,2
Affiliations : 1 Institut Jean Lamour, UMR 7198-CNRS, Université de Lorraine, Nancy F-54011, France. 2 Department for Materials Science, Functional Materials, Saarland University, Saarbrücken D-66123, Germany

Resume : NiO has great potential applications in organic photovoltaics and catalysts. The performance strongly depends on the orientation of NiO, as the discrepant electronic structures in polar {111} and non-polar {100} surfaces. This presentation aims to investigate the controlling growth orientations of NiO thin films on glass substrates by reactive magnetron sputtering at room temperature. In the first part, the influence of total sputtering pressure and oxygen flow rate on the structure, crystallization and growth orientation of single layer NiO thin films is presented. Since the internal stress decreases with the increase of the total pressure, an improvement of the NiO crystallinity is evidenced. Then, a two-step deposition procedure (growth of bilayer thin film) is shown to tune the film growth orientation independently of the deposition conditions. It is observed that the growth orientation of the top layer is determined by that of the bottom layer. For instance, a < 100> oriented NiO seed layer will set the top layer to be < 100> orientation, regardless of its intrinsic growth conditions. Moreover, highly < 111> oriented NiO thin films on glass substrates have been attained by using a < 111> textured Cu2O seed layer. This growth behavior is detailed by high resolution transmission electron microscopy (HRTEM) analyses. The well-matched atomic structures between NiO {111} and Cu2O{111} planes may be the driving force to promote the growth of < 111> oriented NiO.

N.N. XIII.4
11:30
Authors : E. G. Barbagiovanni, V. Strano, G. Franzò, I. Crupi, S. Mirabella
Affiliations : MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania, Italy

Resume : Sensing by ZnO nanostructures is a growing research field due to the promising properties of this semiconductor. However, the complicated surface defect landscape and thus surface functionalization are not well understood. We consider this problem for the case of low cost ZnO nanorods (NRs) prepared by chemical bath deposition on a seed layer. Photoluminescence (PL) measurements identified two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (Vo). A transient behaviour in the PL intensity of the Vo states was found to be sensitive to the ambient environment and to NR post-growth treatment. For annealing in an O2 environment, the transient behavior was suppressed, because of a reduced number of surface Vo states. A similar result holds for NRs measured in vacuum where there is no available O2 to affect the depletion region. While in air, a large transient was found in samples dried on a hot plate, with a PL intensity decay time, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient indicating a clear role of atmospheric O2 on the surface defect states. A new model for a transient in the ionization state of the surface Vo due to band bending with respect to the Fermi level is proposed. The results have implications for sensing and photovoltaic applications of ZnO NRs.

N.N. XIII.5
14:30
Authors : N. Jaber (1), J. Wolfman (1*), C. Daumont (1), B. Négulescu (1), A. Ruyter (1), G. Feuillard (1), M. Bavencoffe (1), T. Sauvage (2), B. Courtois (2), H. Bouyanfif (3), J.L. Longuet (4), P. Andreazza (5),C. Autret-Lambert (1), F.Gervais (1).
Affiliations : 1GREMAN lab., UMR7347 CNRS, Université François Rabelais, Parc de Grandmont, 37200 Tours, France; 2 CEMHTI lab., UPR3079 CNRS, 1D Av. De la Recherche Scientifique, 45071 Orléans, France; 3 LPMC lab., UPJV, 33 route de Saint Leu 80039 Amiens, France; 4 CEA, DAM, Le Ripault, F-37260 Monts, France 5ICMN lab., UMR7374 CNRS, Université d’Orléans, 1bis rue de la Férollerie 45071 Orléans, France

Resume : The most efficient multifunctional piezoelectric materials are lead-based (PZT [(PbZrO3)1-x(PbTiO3)x] and PMN-xPT [(PbMg1/3Nb2/3O3)1-x(PbTiO3)x] and therefore are about to be banned by European RoHS directive. Their piezoelectric coefficients peak in the vicinity of the so-called morphotropic phase boundary (MPB) separating two ferroelectric phases with different structures : one is rhombohedral (once poled for PMN-xPT) and the other is tetragonal [1,2]. Thus alternative lead-free materials are required and an obvious direction is to look for MPBs in other ferroelectric solid solutions. BiFeO3 (BFO) being a ferroelectric (TC~1100K) with record polarization (100µC.cm-2) and a rhombohedral structure is a good starting point. Indeed MPBs have been found in ceramic solid-solutions of BFO with tetragonal ferroelectric perovskite phases with a strong increase of d33 (up to 140 pm/V for BaTiO3) [3]. However, MPBs can also be induced by chemical substitution in new systems for which the end member of the phase diagram does not need to be a ferroelectric perovskite. In this work, we report the exploration of the (BiFeO3)1-x(GaFeO3)x system, where GaFeO3 is piezoelectric and crystallizes in a non-perovskite orthorhombic structure. Composition spread epitaxial Ga-doped BFO (BGFO-x) films were pulsed laser deposited onto La0.8Sr0.2MnO3 electrodes. Composition gradients were characterized by WDX, RBS and XPS while structure and phase analysis was realized by X-Ray micro-diffraction and TEM. Piezoelectric properties were characterized at various length scales with PFM and laser interferometry. All compositions were found to exhibit typical hysteretic ferroelectric behavior with a slight reduction of ferroelectric domain sizes upon Ga doping. A change of symmetry associated with rapid lattice parameters variation has been evidenced just below 6% of Ga doping and is correlated with a sharp enhancement of d_33^eff , probably resulting from the presence of a MPB. The maximum〖 d〗_33^eff (55pm/V for a film thickness of 135nm) shows no extrinsic domain wall contribution and compares to the best PZT value for the same film thickness.

N.N. XIV.2
15:00
Authors : K.Fleischer, O. Mauit, I.V. Shvets
Affiliations : School of Physics, Trinity College Dublin, Ireland

Resume : Ultrathin films of Fe3O4 have been grown epitaxially on nearly lattice matched MgO(001). The stability of 4 nm thick films in ambient air and under annealing in an oxygen atmosphere at 570K has been studied. By magneto optical (MOKE) and Raman measurements, we can confirm the presence of the Fe3O4 phase and the formation of a maghemite top layer, passivating the magnetite thin film. In a second step, we are able to demonstrate that this top layer oxidation in ambient air can be prevented by a 2 nm thick magnesium ferrite passivation layer, while a thicker 20 nm MgO layer prevents oxidation even at elevated temperatures. First results of employing the ultrathin Fe3O4/MgFe2O4 layers as building blocks for novel magnetic nanolaminate materials will be presented.

N.N. XIV.4
 
Doping effects and related applications (II) : N. Laidani, M. L. Grilli
16:00
Authors : Philipp Gutruf, Sumeet Walia, Charan Manish Shah, Sharath Sriram, and Madhu Bhaskaran
Affiliations : Functional Materials and Microsystems Research Group, School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia.

Resume : The demand for stretchable electronics has increased drastically in recent years, owing to the growing popularity of wearable and compact devices such as smart watches and fitness gear. However, these devices use conventional rigid technology in a flexible housing. Here, we demonstrate precursors for fully stretchable devices by integrating high quality oxide thin films into a rubber substrate. We show a universal process for transferring planar, transparent indium tin oxide (ITO) thin films on to elastomeric polydimethylsiloxane (PDMS) substrates. This process overcomes the challenge of incorporating high-temperature-processed crystalline oxide materials with low-temperature organic substrates by using the weak adhesion at the platinum-silicon interface. We demonstrate control over film thickness and show feature sizes down to 2.5 µm by using standard micro fabrication techniques. Counterintuitively, the ITO thin film electrodes on PDMS are shown to withstand uniaxial strains of 15%. We explore the capabilities of the electrodes by characterising the devices using resistance vs. strain measurements and in situ scanning electron microscopy, revealing a novel surface structure called micro-tectonics which is responsible for the high stretchability of the oxide thin films. We show that the ITO layer forms overlapping plates that can move independently from each other forming a fully functional stretchable surface. Reference: P. Gutruf et al. "Transparent functional oxide stretchable electronics: micro-tectonics enabled high strain electrodes." NPG Asia Materials 5 9 e62 (2013).

N.N. XV.1
16:15
Authors : Gun-Hwan Lee, Jung-Huem Yun, Sung-Hoon Lee
Affiliations : Korea Institute of Materials Science(KIMS)

Resume : The development of flexible substrates that are based on polymer films is of critical importance to display and photovoltaic applications. Flexible substrates offer the advantages of mechanical flexibility, design freedom, optical transparency, lightweight, and cost-effectiveness. A number of inorganic functional coatings on polymers have critical properties such as water impermeability and electronic conductance, which are required for display, electrochromics and photovoltaic applications. In this study hybrid transparent conductive oxide films which had the structure of TCO/ AgOx /TCO and TCO/Ag nano wire layers were deposited on a flexible substrate as a function of inter layers thickness and chemical status by using DC roll-to-roll magnetron reactive sputtering system. The influences of the inter layer thickness and oxygen partial pressure on the microstructure, optical properties, flexibilities and electrical properties were studied. The high quality hybrid ITO films were deposited at RT with a resistivity of 1.05x10-4Ωcm and the transparency of batter than 89%. Change of electrical and optical properties according to the inter layers and plasma conditions was also observed with XRD, TEM, and XPS. TCO films deposited at RT showed nanocrystalline phases evolved on the amorphous TCO layer. Very flat surface roughness could be obtained at RT, while surface roughness of the films was increased due to the formation of grains over than 70℃. Consequently, high quality hybridTCO films could be prepared by DC roll-to-roll sputtering with high deposition rate and at low deposition temperature; a specific resistivity of 1.05x10-4Ωcm, and Rp-vand Rrms values of surface roughness about less than 4 nm and 0.5 nm. The mechanical failure of brittle oxide and TCO coatings on flexible polymers is a serious issue. The formation of defects, such as cracks and debonding in TCO films may be inevitable in situations in which bend geometries are required, because of the large difference between the elastic properties of TCO and polymers. The initiation and subsequent developments of defects mainly depend on the coating material, thickness, and interfacial adhesion. Thus, it is important to have a clear understanding of the failure behavior of coatings in the case of bend geometries, in order to prevent the destruction of devices in which they are used. Flexibility of hybrid TCO films was measured as functions of the bending radius and bending cycle in bend geometries and then shown an excellent flexibility. It will be considered that these experimental results can be applied to the TCO substrate of flexible display devices.

N.N. XV.2
16:45
Authors : C. Davesnne, Ph. Marie, C. Labb?, C. Frilay, and X. Portier
Affiliations : CIMAP, CEA/UMR CNRS 6252/ENSICAEN/Université de Caen Basse Normandie 6, Boulevard Maréchal Juin, 14050 Caen, France

Resume : Zinc oxide (ZnO) is a II-VI semiconductor material possessing remarkable electronic and optical properties for optoelectronic applications. Rare earth doping of ZnO is investigated for the fabrication of white LEDs. For instance, the green light can be produced by terbium ions (Tb3 ) and the red emission can be achieved by europium ions (Eu3 ). The contributions of these two rare earth emissions in addition to that of ZnO lead to a white light. The case of Eu doping in a ZnO matrix is interesting since two electronic configurations of ions are generated in ZnO: Eu2 and Eu3 . It results a much lower luminescence efficiency of the Eu3 than expected. In the present study, Eu doped ZnO (Eu:ZnO) films were grown on (100) silicon substrates by radiofrequency (RF) magnetron sputtering using a pure ZnO target. Doping was obtained by arranging calibrated Eu oxides (Eu2O3) pellets on the surface of the ZnO target. Using characterization techniques such as X-ray diffraction, X-ray photoemission spectroscopy, transmission electron microscopy, spectroscopic ellipsometry and photoluminescence spectroscopy, the present work aims at studying the effect of the doping rate on the film structure and its photoluminescence properties. The goal is also to cinfirm the presence of Eu2 and Eu3 in the films and to investigate their localization in the ZnO film. In addition, electrical properties and their evolution with the europium doping rate are reported.

N.N. XV.4
17:00
Authors : A. Mesaros, R. B. Mos, M. Nasui, T. Petrisor Jr, Mihai Gabor, B. S. Vasile, L. Ciontea, T. Petrisor
Affiliations : Technical University of Cluj-Napoca, Romania; University "Politehnica" from Bucharest, Romania

Resume : Ultra-small superparamagnetic Ga1.1Fe1.9O4 nanoparticles have been successfully synthesized using a facile and efficient one-pot solvothermal method. This approach is based on the thermal decomposition of Ga(C5H7O2)3 and Fe(C5H7O2)3 in triethyleneglycol, which acts as both solvent and, capping ligand. The structure, morphology and magnetic properties of the ultra-small superparamagnetic Ga1.1Fe1.9O4 nanoparticles have been investigated by X-ray diffraction, FT-IR, HRTEM, SAED, VSM and SQUID. The XRD investigations reveal the formation of the cubic spinel structure, while TEM images show non-agglomerated spherical nanoparticles with an average particle size range between 4.5 to 9 nm. Magnetization vs temperature, M(T), measurements, performed by SQUID, have demonstrated that the resulting nanoparticles show high saturation magnetization and superparamagnetic behaviour at room temperature. Moreover, ligand exchange has been also carried out in order to produce stable dispersions of Ga1.1Fe1.9O4 nanoparticles in polar media. The preliminary studies on using of as-obtained Ga1.1Fe1.9O4 nanoparticles as magnetic pinning centers in YBa2Cu3O7 thin films are performed. Acknowledgments: This work was supported by the EU - FP7/2007-2013 - Grant Agreement No. 280432, EUROTAPES project and by the Post‐Doctoral Programme POSDRU/159/1.5/S/137516, project co‐funded from European Social Fund through the Human Resources Sectorial Operational Program 2007‐2013 and CNCSIS-UEFISCSU.

N.N. PIII.10
17:00
Authors : C. Baratto, E. Comini, M. Donarelli, F. Rigoni, G. Faglia, G. Sberveglieri
Affiliations : CNR-INO SENSOR Lab. and University of Brescia, Dept. of Information Engineering, Via Valotti, 9 25133 Brescia, Italy

Resume : In the past decade semiconductor nanowires have emerged as promising building blocks for nanoscale optoelectronic devices. One of the most interesting materials used for nanostructure fabrication is the wide-bandgap semiconductor ZnO, which is a very attractive candidate for blue and UV optoelectronics. ZnO prepared by evaporation condensation technique in the form of high aspect ratio nanowires and microwires. The photoluminescence emission properties of the nanostructures were analyzed as a function of the surface treatment (plasma etching) and as a function of the nanowire diameter. Nanowires were analyzed both as deposited as a mesh on silicon substrate and dispersed over glass and Si substrate, and single nanowires were precisely designated by mean of EBL. Waveguiding properties have been demonstrated to be dependent on the wire dimensions (microwires) and on the laser wavelength. The ZnO nanowires may be applied as PL optical gas sensor and evanescent optical gas sensor, and in heterojunction with p-type material, for LED applications. The research leading to these results has received funding from the European Communities 7th Framework Programme under the grant agreement NMP3-LA-2010-246334, ‘‘ORAMA’’.

N.N. PIII.11
17:00
Authors : M.L. Grilli1, F.R. Lamastra2, F. Menchini1, T. M. Dikonimos1, A. Mittiga1, P. Nunziante3, A. Piegari1, F. Nanni4
Affiliations : 1 ENEA, CR Casaccia, Via Anguillarese 301, 00123 Roma; 2 Italian Interuniversity Consortium on Materials Science and Technology (INSTM), Research Unit Roma Tor Vergata, Via del Politecnico 1- 00133 Rome, Italy; 3 Department of Chemical Sciences and Technologies, University of Rome "Tor Vergata", Via della Ricerca Scientifica 00133, Rome, Italy; 4 Department of Enterprise Engineering, University of Rome Tor Vergata, Via del Politecnico 1-00133 Rome, Italy.

Resume : Nickel oxide (NiO) attracts considerable interest for its photocatalytic properties in applications as battery, electrochromic, chemical sensing, etc. and for its potential applications as p-type transparent semiconductor. High conductivity p type NiO films were fabricated by radio frequency sputtering starting from a Ni target in different Ar+O2 pressures. The effect of the different growth parameters on the structural, chemical, optical and electrical properties of the films was investigated. Film resistivity decreased by increasing the oxygen partial pressure in the sputtering gas and reached the value of 1.6x10-2 Ohmcm for films grown in pure oxygen atmosphere. NiO fibers were produced by electrospinning starting from a solution prepared by dissolving 1 g of polyvinylpyrrolidone (PVP) and 1.5 g of Ni (II) acetate tetrahydrate in 15 ml of ethanol. Fibers were deposited on different substrates, including NiO and Ni thin films grown on quartz substrates. Electrospun mat calcined in air at 600°C consisted of randomly oriented fibers with diameters ranging between 40-100 nm. Phase analysis performed by XRD showed the presence of a crystalline NiO phase. Hybrids NiO fibers/NiO films were fabricated to take advantage of the different microstructure properties and enhance electrodes performances.

N.N. PIII.12
17:00
Authors : Zied Othmen , Kais Daoudi1, Riad Othmen , Ali Madouri, Meherzi Oueslat, and B.rahim Dkhil
Affiliations : Unité Nanomatériaux et Photonique, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092, Tunis, Tunisie. Department of Applied Physics, College of Sciences, University of Sharjah, P.O. Box 27272, Sharjah, United Arab Emirates. CNRS/LPN, Route de Nozay, F-91460 Marcoussis, France. Laboratoire Structures, Propriétés et Modélisation des Solides, CNRS-UMR 8580, Ecole Centrale Paris, France.

Resume : Since the discovery of graphene [1] a huge interest has been devoted to this material in view of its integration in various technological applications ranging from nonmetric electronic devices to large scale solar cells. So far, the deposition of a thin monolayer of graphene has been achieved using various techniques on various substrates materials [2]. In order to extend our knowledge and benefit from the amazing electronic properties of this material we have here successfully transferred a graphene layer on top of a La0.7 Sr0.3CoO3 (LSCO) thin filmusing chemical vapor deposition (CVD) technique and studied its consequence on the Co spin state and local structure distortions. Indeed, LSCO cobaltites [3] are known to be mixed-valence systems (Co3+/Co4+ ) characterized by rich and complex physical properties. The Co-ions (Co3+ ) and (Co4+ ) are able to take three different spin states: low-spin (LS), intermediate-spin (IS) and high-spin (HS) states. The predominant spin state in 20nm-thick film of LSCO grown on LaAlO3 substrate is the LS state where Jahn-teller (J-T) lattice distortions are inactive in contrast to the IS state. Using Raman spectroscopy we unambiguously show that the J-T active Raman modes are induced in the Graphene/LSCO nanostructure which drastically differs to the situation of LSCO without graphene. This observation is attributed to a charge transfer from graphene to LSCO promoting the IS states which in turn activates the Raman modes associated to the J-T distortions.

N.N. PIII.15
17:00
Authors : Anna Białous, Maria Gazda, Katarzyna Grochowska, Joanna Reszczyńska, Adriana Zaleska, Gerard Śliwiński
Affiliations : Anna Białous, Katarzyna Grochowska, Gerard Śliwiński: Polish Academy of Sciences, The Szewalski Institute, Photophysics Dept, 14 Fiszera St., 80-231 Gdańsk, Poland; Maria Gazda: Gdańsk University of Technology, Faculty of Applied Physics and Mathematics, 11/12 Narutowicza St., 80-233 Gdańsk, Poland; Joanna Reszczyńska, Adriana Zaleska: Gdańsk University of Technology, Faculty of Chemistry, 11-12 Narutowicza St., 80-233 Gdańsk, Poland

Resume : In recently reported works the performance improvement of dye-sensitized solar cells (DSSC) assembled with use of Ti/TiO2 interface is ascribed to its low charge transfer resistance and low recombination rate of charge carriers. It refers to DSSC devices on metal foil substrates where the porous TiO2 electrode is produced using the doctor blade method followed by sintering. However, the production process preceded by sputtering of the Ti film on preheated metal substrate and synthesis of the Ti/TiO2 interface seem too complicated, time consuming and associated with a number of process parameters to be controlled. In this work the nanoporous TiO2 films forming the TiO2-Ti junction obtained by a one-step synthesis using pulsed laser deposition (PLD) at atmospheric pressure are reported. It is shown that reliable interconnection of the film with Ti foil can be produced in air under conditions of standard temperature and pressure and without thermal pre-and post-treatment. Observations performed with both the scanning electron and confocal microscopes confirm the presence of porous TiO2 films. Data on the film composition and crystalline phases obtained from the XRD, EDX and Raman measurements indicate on the relatively high anatase/rutile ratio (>75%) with a small amount of TimNn in dependence on the film preparation conditions. AB and KG acknowledge the National Science Centre of Poland for financial support via grants 2012/07/N/ST5/02134 and 2012/07/N/ST5/02139.

N.N. PIII.16
17:00
Authors : M. Purica1, E. Budianu1, A. Dinescu1, V.Musat2, Florin Comanescu1
Affiliations : 1National Institute for R&D in Micro technologies, Bucharest, Romania 2Centre of Nanostructures and Functional Materials, “Dunarea de Jos” University, Galati, Romania

Resume : One-dimensional ZnO nanostructures are multifunctional nanomaterials with high potential applications in the field of optoelectronics, photovoltaics, sensing due to their properties and their easy synthesis in the form of nanowires using low-temperature hydrothermal process. We report a method which combines e-beam lithography (EBL) and a low temperature (<100 oC) hydrothermal method to achieve localized growth of ZnO nanowires(ZnO NWs) and microroads on wide range of patterned substrates such as glass, quartz, Si and SiO2/Si and ITO/glass. Our method for ZnO NWs patterned growth consists of the three stages: (1) configuration interdigitated metallic electrodes from Cr/Au of 20/150 nm thickness with distance between electrodes in the range of 1.5 -6 µm using laser photolithography ; (2) coating with PMMA ( hydrophobic polymer layer which inhibits growth) by spinning and defining the growth region using electron-beam lithography ( EBL) ; (3) seeding the substrate with discontinuous dispersed ZnO nanoparticles and growth of ZnO nanowires in aqueous solution of zinc nitrate hydrate and hexamethylenetetramine ([Zn2+]:HMT] =1:1) at 90 oC . The quality of the ZnO NWs synthesized through the hydrothermal process has been characterized by SEM, Raman spectroscopy and XRD. The obtained 1D nanostructures are nanorods and nanowires types, with aspect ratio (length/diameter) ranging from 5 to 50, and well crystallized with Wurtzite-type hexagonal pattern and <002> preferential orientation and electrical connected the two adjacent gold electrodes through forming complex interconnected nanowire networks. Current-voltage characteristics showed a photoconductive behavior and UV radiation and gas sensitivity

N.N. PIII.18
17:00
Authors : Qin Wei Wei, Gao Zhi Qiang, Li Ta0, Hu Xue Feng, Huang Shengming, and Wei Zhang
Affiliations : State Key Laboratory of Material-oriented Chemical Engineering and School of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China

Resume : ZnO nanogenarator, to utilize the environmental mechanical energy, which is available from irregular vibrations and human activity with a wide spectrum of frequencies and time-dependent amplitudes, have demonstrated to produce micro-watt power output and to drive micro-sensor. .However so far the power output from NW nanogenarator based on chemical synthesis ZnO nanowire is still far away from a milli-power output source , which requested by most applications of individual sensor. Physical vapor deposition of ZnO can largely improve the crystal graphical property of the grown ZnO but limit with small growth area. To achieve good ZnO piezoelectric property and grow large area with high power output is desirable. In this paper, Sol-gel technology was used to prepare ZnO thin film on Si substrate, the characteristic of the samples was measured by XRD, AFM, and SEM. The XRD patterns showed that ZnO thin film had a high (002) orientation with compact hexagonal wurtzite structure. The AFM and SEM microphotograph showed ZnO thin film had a smooth and dense surface, the thickness of the sample was approximately 80 nm. The grain size gradually increased with annealing temperature. Sol-gel grown ZnO film are then patterned into a micro power source. The power output from ZnO micro-power sourse can reach upto 3mW.

N.N. PIII.21
17:00
Authors : A. Carretero-Genevrier *1, Judith Oró-Solé 2, Jaume Gázquez 2, Teresa Puig 2, Xavier Obradors2, Clément Sanchez3, Etienne Ferain4, Juan Rodríguez-Carvajal5, Narcís Mestres*2
Affiliations : 1 Institut des Nanotechnologies de Lyon (INL) CNRS- Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France; 2 Institut de Ciència de Materials de Barcelona ICMAB, Consejo Superior de Investigaciones Científicas CSIC, Campus UAB 08193 Bellaterra, Catalonia, Spain; 3 Laboratoire Chimie de la Matière Condensée, UMR UPMC-Collège de France-CNRS 7574. Collège de France, 11 place Marcelin Berthelot, 75231 Paris, France; 4 it4ip sa, 1 avenue Jean-Etienne Lenoir, 1348 Louvain-la-Neuve, Belgium; 5 Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France

Resume : Manganese oxides octahedral molecular sieves (OMS) with mixed valence frameworks have been widely used as bulk material in catalysis, semiconductor industry, and batteries. Monolithic direct integration of OMS with vertically oriented crystals on a semiconductor platform is challenging due to difficulties on preserving epitaxy, crystalline phase, and composition. Here, we developed a new strategy to produce vertical epitaxial single crystalline manganese oxide OMS nanowires thin films with tunable composition and enhanced ferromagnetic properties on Si substrates by using a chemical solution deposition approach [1]. The nanowire growth mechanism involves the use of track-etched nanoporous polymer templates combined with the controlled growth of quartz thin films at the Si surface, which allowed the epitaxial stabilization and crystallization of OMS nanowires. α-quartz layers were obtained by thermally activated devitrification of the native amorphous silica surface layer assisted by a heterogeneous catalysis driven by alkaline earth cations (Sr2+, Ba2+ or Ca2+) present in the precursor solution [2]. Therefore, the combination of soft-chemistry and epitaxial growth opens new opportunities for the effective integration of novel technological functional complex oxides nanomaterials on Si substrates [3]. 1. A. Carretero-Genevrier et al Chem.Soc.Rev 43, 2042 (2014) 2. A. Carretero-Genevrier et al Science 340, 827 (2013) 3. A. Carretero-Genevrier et al Chem. Mater 26 1019 (2014)

N.N. PIII.22
17:00
Authors : Philipp Gutruf, Sumeet Walia, Eike Zeller, Sharath Sriram and Madhu Bhaskaran
Affiliations : Functional Materials and Microsystems Research Group, RMIT University, GPO Box 2476, Melbourne, Victoria, Australia.

Resume : Recently many functionalities only associated with rigid electronics have been demonstrated on a flexible substrate, indicating that flexible devices have a high potential to operate on par with rigid electronics. Furthermore, flexible electronics offer a distinct advantage by organically conforming to irregular surfaces, this enables a new class of electronics that seamlessly integrates with the human body. Fully stretchable electronics pose a challenge for material science and micro fabrication to create devices with the ability to operate impeccably under various mechanically-stressed states. Here, we introduce a distinctive micro-tectonic effect to enable oxygen-deficient, nano-patterned zinc oxide (ZnO) thin films on an elastomeric substrate to realize large area, stretchable, transparent, and ultra-portable sensors. We harness the unique surface structure to create stretchable gas and ultra-violet light sensors, both of which outperform their rigid counterparts under room temperature conditions. The sensors show a high sensitivity to flammable and toxic gases as well as radiation in the UV-A and B band. We characterise the device performance in undeformed and strained states using customised in situ techniques. We demonstrate full functionality under strain as well as an increased sensitivity through micro-tectonic surfaces by comparison to their rigid counterparts. Additionally we show excellent control over dimensions by embedding nanometre ZnO features in an elastomeric matrix which function as tunable diffraction gratings, capable of sensing displacements with nanometer accuracy.

N.N. PIII.25
17:00
Authors : M. Coeler (a), T. Nestler (c), U. Wunderwald (a), J. Friedrich (a,b), T. Leisegang (c), D. C. Meyer (c)
Affiliations : (a) Fraunhofer THM, D-09599 Freiberg, Germany (b) Fraunhofer IISB, D-91058 Erlangen, Germany (c) TU Bergakademie Freiberg, Institut für Experimentelle Physik, D-09596 Freiberg, Germany

Resume : Rechargeable solid state battery systems with alternative ion-conductive systems are of great interest in research on novel mobile energy storage concepts. For the promising aluminium ion system the spinel structure of λ-MnO2 offers the appropriate 3D channels for intercalation cathodes. As the chemical synthesis of AlMn2O4 has not been established yet, the compound is formed by electrochemically loading of λ-MnO2 spinel with aluminium ions. The synthesis of metastable λ-MnO2 is attained not on a direct way but through delithiation of spinel LiMn2O4 similar to Xue et al.[1]. Commercial LiMn2O4 powder was etched with 18M H2SO4 at 40 °C. Powder XRD measurements report the lithium reduced spinel structure Li0,04Mn2O4. The quantitative analysis of residual Li content via ICP-OES confirmed a Lithium decrease of a factor of about 10. For the future, cyclic voltammetry measurements in aluminium half cells as well as the aluminium intercalation to produce AlMn2O4 as cathode material are going to be evaluated. In addition to that, further experiments will be conducted to evaluate materials suitably for high-energy-density aluminium ion batteries. [1] Y. Xue et al. – Material Letters, 62, 2008, 3884-3886.

N.N. PIII.27
17:00
Authors : Kashif Safeen1,2, V. Micheli2, R. Bartali2, G. Gottardi2 and N. Laidani2
Affiliations : 1 University of Trento, Department of Physics, Via Sommarive 15, 38123 Povo, Trento, Italy 2 Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo, Trento, Italy

Resume : Low temperature growth of various structural phases of TiO2 is particularly significant for practical applications. In this work, the deposition conditions for the growth of anatase and rutile phase at low temperature (≤ 300 °C) were optimized. TiO2 films were deposited by RF sputtering of a TiO2 target in argon and argon-oxygen plasma (20 % O2) at various substrate temperatures (Tsub = RT-400 °C). The plasma properties were investigated using OES in wide range values of gas composition (0-50 % O2 in Ar discharge). The structural, optical and chemical properties were studied by mean of XRD, UV-visible-NIR spectroscopy and XPS. The XRD results show the formation of anatase phase for the films grown in Ar-O2 plasma over the whole range of temperature. In contrast, the films deposited in argon discharge largely persist in amorphous phase at temperature ≤ 200 °C and revealed the formation of single rutile phase at ≥ 300 °C. The oxygen vacancies detected by XPS analysis for the films deposited in Ar plasma facilitate the growth of rutile phase at low temperature (∼300 °C). The anatase films have interesting optical characteristics such as high transmittance (∼ 85 %) and wider optical band gap (∼3.25 eV) compared with rutile films (∼78 % and 3 eV). Our results demonstrate that oxygen negative ions, oxygen vacancies and surface energy conditions at the substrate are the key parameters controlling the phase and hence the optical properties of the prepared films at low temperature.

N.N. PIII.28
17:00
Authors : N. Cioatera 1, M. Florea 2, G. Epurescu 3, R. Birjega 3, S. Somacescu 4, B. Mitu *3
Affiliations : 1 University of Craiova, Calea Bucuresti 107I, Craiova, Romania 2 University of Bucharest, Faculty of Chemistry, Bucharest, Romania 3 National Institute for Laser, Plasma and Radiation Physics, Magurele - Bucharest, Romania 4“Ilie Murgulescu”, Institute of Physical Chemistry, Bucharest, Romania

Resume : Intermediate Temperature-Solid-oxide Fuel Cells (IT-SOFCs) has a high potential in the application of clean and efficient electric power generation. Major problems in the field can be addressed by decreasing the operation temperature. In this work the symmetrical cells were developed in order to assess the cathodes performance. The materials with perovskite structure synthesized by “citrate” method were used as targets for thin films deposition by RF assisted pulsed laser deposition system (RF-PLD). The compositions of the targets are as following: Nd0.6Sr0.4Co0.8Cu0.2O3-δ,(NSCC), Pr0.5Ba0.5Cu0.8Fe0.2O5+δ (PBSC) and La0.5Sr0.5Co0.8Fe0.2O3-δ (LSCF), respectively. The electrochemical testing of these materials as cathodes in solid oxide fuel cells were carried out using ceramic disc-shaped electrolytes based on YSZ (8% mol. Y2O3 doped ZrO2). Additionally, Ce0.9Gd0.1O2-δ (CGO) synthesized from hydrated nitrate precursors via a modified Pechini method was used as buffer layer between cathodes and electrolyte. The compatibility of the different cathodes and the electrolyte was investigated by SEM and AFM. Studies on structural properties and surface chemistry were performed by XRD, Raman and XPS techniques. It was found that the porous texture of the films is strongly dependent on the deposition method and composition. The electrochemical tests were performed by impedance spectroscopy (EIS) using systematic variation of temperature in the range 600-900 ºC and O2 partial pressure.

N.N. PIII.29
17:00
Authors : Jolita Sakaliūnienė(a), Viktoras Grigaliūnas(a), Tomas Šalkus(b), Brigita Abakevičienė(a,c), Sigitas Tamulevičius(a)
Affiliations : (a) Institute of Materials Science of Kaunas University of Technology, K. Baršausko str. 59, LT-51438 Kaunas, Lithuania; (b) Faculty of Physics, Vilnius University, Saulėtekio av. 9/3, LT-10222 Vilnius, Lithuania; (c) Department of Physics, Kaunas University of Technology, Studentų str. 50, LT-51368 Kaunas, Lithuania

Resume : The aim of this research is to find out platinum electrode geometrical effects on ionic conductivity of yttria stabilized zirconia (YSZ) thin films (thickness of 600 nm). YSZ films were deposited using electron beam (e-beam) evaporation technique. As a source material for e-beam evaporation of electrolyte, the synthesized yttria stabilized zirconia ceramic powders containing 8 mol % of Y2O3 was used. Conventional YSZ ceramics are used in solid oxide fuel cells (SOFC) as electrolyte. μ-SOFC challenge is to miniaturized SOFC system to “micro” size. By reducing the electrolyte layer thickness, the diffusion path length of the oxygen ions can be decreased, what reduces operating temperature of the cell. Conventionally, electrolyte thin films impedance measurements are carried out covering platinum paste on the surface, as well as physical evaporation techniques are used for the electrode formation on the electrolyte surface. The major disadvantage of such sample preparation technique is inaccurate results, because it is difficult to separate the different impedance contributions. Lower distance (as close as possible to the thickness of thin film) between Pt electrodes on the YSZ surface allows a separation of bulk and grain boundary impedances in thin YSZ films. In this research an optimized Pt electrode geometry is offered to characterize thin ion conducting films by impedance spectroscopy, applying magnetron sputtering, lithography and etching processes.

N.N. PIII.31
Start atSubject View AllNum.
 
Microstructure, stress and defects in oxide nanostructures and interfaces and nanotechnology (III) : H. L. Meyerheim
09:00
Authors : K. Bouras1*, J.- L. Rehspringer2, G. Schmerber2, D.Ihiawakrim2, C.Leuvrey2, S. Colis2, T.Fix1, Ferblantier1, A. Dinia2 and A. Slaoui1
Affiliations : 1ICube, CNRS-Universite de Strasbourg, 23 rue du Loess, BP 20 CR, 67037 Strasbourg Cedex 2, France 2IPCMS, CNRS-Universite de Strasbourg, UMR7504, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France

Resume : Tin dioxide is one of the most attractive materials studied in the last decade due to its several applications such as optoelectronic devices, gas sensors, and solar cells. It is n- type semiconductor with a wide band gap (around 3.6 eV for bulk material at 300 K). Doping SnO2 films with rare earth (RE) elements (such as Yb, Pr, Tb, Nd) can enhance their photoluminescence properties thanks to the optical transitions involving the 4f shell of the dopant. However, the transparency and structural properties of the RE doped SnO2 films should not be affected. In this work, we have synthesized undoped SnO2 and Yb doped SnO2 (Yb:SnO2) powders by the sol gel method in order to understand the insertion process of Yb in SnO2 matrix and to produce luminescent materials for photon shifting purpose. SEM and TEM micrographs show that the grain size is homogenous for Yb:SnO2 powders. The crystallinity, structure and particles size of the powders were determined using XRD measurements. We found that the crystalline tetragonal rutile phase is achieved upon an annealing temperature of 700?C. Furthermore, a slight diffraction angle shift toward higher angles is observed with increasing Yb content, indicating Yb incorporation. No secondary phases like Yb oxides are detected. The optical properties were studied by the UV-Visible-NIR spectroscopy and revealed Yb related absorption band in the NIR region. Moreover, a decrease of the absorption threshold energy with respect to the Yb content was observed. The intensity of Raman peaks decreases gradually as the Yb content increases. Finally, the investigation of the photoluminescence properties under a 325 nm laser excitation show intense emission at 980 nm attributed to a transition in the Yb energy level. such strong PL signal indicates that the trivalent Yb3 ions are successfully inserted and optically active. An efficient energy transfer might occur from the SnO2 host to Yb3 ions.

N.N. XVI.1
09:15
Authors : C. Lefevre, A. Demchenko, F. Roulland, V. Favre-Nicolin, N. Viart
Affiliations : Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), Strasbourg ; Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), Strasbourg ; Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), Strasbourg ; CEA, INAC-SP2M & Univ. Grenoble Alpes, F-38000 Grenoble ; Institut de Physique et Chimie des Matériaux de Strasbourg (UMR 7504), Strasbourg

Resume : Magnetoelectric materials open the way toward new applications through controlling magnetic or electric polarization with electric or magnetic field, respectively. Ga2-xFexO3 (GFO) compounds are predicted to be magnetoelectrics with non-zero magnetization at room temperature. High quality GFO thin films with quite similar physical properties as bulk materials have been recently elaborated. Gallium and Iron are distributed in four non-equivalent cationic sites in the structure. The determination of the cationic distribution within the structure is a key point for the knowledge of these phases but extremely tricky to determine owing to the relatively small amount of material to probe. One of the many benefits of synchrotron radiation is the ease of energy adjustment of the X-ray beams that allows discriminating the cations contribution in different sites. Diffraction Anomalous Near Edge Structure experiments have been recorded at the gallium and iron edges using the BM02 beamline of the ESRF. A software, “FitREXS”, has specially been developed for this purpose using the Python language and may be easily adapted to any system. Results clearly demonstrate the efficiency of the method for the determination of sites occupancies. Additional parameters such as the orientation of the cells along the growth direction have also been taken into account and will be discussed

N.N. XVI.2
10:45
Authors : Dario Neri, Silvia Leonardi, Francesco Fumagalli, Fabio Di Fonzo
Affiliations : Center for Nano Science and Tecnology @PoliMi, Istituto Italiano di Tecnologia; Center for Nano Science and Tecnology @PoliMi, Istituto Italiano di Tecnologia; Center for Nano Science and Tecnology @PoliMi, Istituto Italiano di Tecnologia; Center for Nano Science and Tecnology @PoliMi, Istituto Italiano di Tecnologia

Resume : SnO2-based Transparent Conductive Oxides (TCO) are currently widely used in different applications, e.g. as electrodes for photovoltaic, water splitting and fuel cells, for their high performances in terms of carrier density and mobility, low costs, non-toxicity and high transparency in the visible spectrum. To maximize the performances a proper balance between surface-to-volume ratio, to enhance the active surface, and crystallinity grade, to improve the carriers transport, is required. Despite some SnO2-based TCO porous films have been already realized, hierarchical nanostructured contacts has not been done yet. In this work Pulsed Laser Deposition technique has been adopted for this purpose. The resulting tree-like nanostructured film can be tuned in a wide range of porosity, maintaining excellent electrical properties. Electrodes performances have been analyzed from electrical, electrochemical and optical points of view. A gold contact evaporated on the top of the films has been used to determine the conductive performances. With Electrochemical Impedance Spectroscopy we monitored their behavior in electrochemical cells. UV-vis measurements have proved that the optical path can be engineered altering the porosity of the film. These films are suitable for subsequent doping or functionalization. In the present work a novel thermal doping process with Fluorine precursor has been performed as an efficient and facile technique to produce hierarchical nanostructured FTO films.

N.N. XVII.2
11:15
Authors : S. Fabert (a,b), R. Meunier (a,b), P.Y. Thoulon (a), P.Y. Jouan (b), M. Carette (b), M. Ricci (a), M.P. Besland (b)
Affiliations : (a) Crosslux S.A. Avenue Georges Vacher 13790 Rousset (FRANCE);
(b) IMN - Institut des Matériaux Jean Rouxel UMR 6502 44322 Nantes (FRANCE)

Resume : Among solar cells of 2nd generation, i.e. based on thin films, CIGSe solar cells have recently reached a world record above 20 %. CIGSe solar cells are often considered as the most promising alternative to Si-based solar cells, thanks to their intrinsic characteristics. A standard CIGSe-based photovoltaic cell is a stacked-layered hetero-structure on a glass substrate: Mo back contact, CIGSe absorber layer, buffer layer (usually CdS obtained by CBD) and the upper ZnO window layer. In the framework of CIGS solar cell industrialization fully fabricated by magnetron sputtering [1], our buffer layer is constituted by Zn(O,S) instead of CdS. Zn(O,S) is deposited by sputtering from a ZnS target in a reactive Ar-O2 plasma. In this study, Zn(O,S) films were deposited on glass substrate by RF magnetron sputtering and DC pulsed magnetron sputtering. The properties of both types of Zn(O,S) films, i.e. chemical, structural, morphological and optical properties, were investigated by XPS, XRD, SEM, ellipsometry and UV-visible spectroscopy and will be presented. In particular, a minimum energy band gap value of 2.6 eV has been obtained for an S/S+O atomic ratio of 0.4 and an average transmittance close to 90%. Such values appear thus very attractive for photovoltaic applications as part of a window layer [2][3]. [1]R. Meunier et al, submitted; oral communication at COFMER'01 and AVS' 61 (2014) [2]A. Grimm et al, Thin Solid Films (2011) [3]B.K. Meyer et al, Applied Physics Letters (2004)

N.N. XVII.4

No abstract for this day


Symposium organizers
Nadhira BENSAADA LAIDANI (Main)Fondazione Bruno Kessler

Centro Materiali e Microsistemi, 18 Via Sommarive, 38123 Trento, Italy

laidani@fbk.eu
Zoe BARBERUniversity of Cambridge

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

+44 1223 334326
zb10@cam.ac.uk
Nathalie JEDRECYUPMC-Sorbonne Universités - INSP

4 Place Jussieu, 75252 Paris Cedex 05, France

jedrecy@insp.jussieu.fr
Holger L. MeyerheimMax-Planck-Institut f. Mikrostrukturphysik - Weinberg 2

Halle Germany

+49 345 5582 633
+49 345 5511223
hmeyerhm@mpi-halle.mpg.de
Tetsuya YamamotoKochi University of Technology

185 Miyanokuchi, Tosayamada-cho, Kami-shi Kochi 782-8502 Japan

+81-887 57 2180
+81-887 57 2181
yamamoto.tetsuya@kochi-tech.ac.jp