2019 Fall Meeting
INFORMATION AND COMMUNICATION TECHNOLOGIESD
Materials for nanoelectronics and nanophotonics
This symposium will cover:
- Materials Synthesis: From 0D to 3D functional nanomaterials including hybrids.
- Properties: Electronics, optical, photonics, luminescent (experimental, analytical, modelling).
- Applications: Electronics, sensing, photonics, plasmonics, luminescent, optoelectronics, energy.
Nanostructures, particularly from inorganic materials, ceramics, carbon, etc. family, are very important candidates because of their extremely high surface-to-volume and morphology-dependent extraordinary properties suitable for many advanced technologies. The ongoing deployments in the direction of confined nanostructures (0D, 1D, 2D) and their porous interconnected 3D networked materials have further become very relevant towards various applications. The porous 3D network material built out of nanoscale building blocks, offers very lot of utilization simplicities and simultaneous easy accessibility of nanoscale features make them very excellent candidates for applications, especially towards electronics and optics. Due to their compact synthesis forms, they can be easily handled or integrated in the desired manner in nanoelectronics devices or sensors. The confined nanostructures from noble metals (Au, Ag, Cu, etc.) have found immense applications in electronics, optoelectronics, sensing, photonics, and waveguides, etc. Nanostructures from metal oxides have been very interesting (fundamental as well applied) materials due to interesting bandgap values (intermediate between metals and insulators), suitable for various advanced electronic, optical, optoelectronic and sensing technologies. When these metal oxides and metals are combined together in nanohybrids, they become further very relevant in terms of understanding the properties and accordingly electronics and optoelectronics applications. The carbon nanostructure family, i.e., fullerenes, carbon nanotubes, graphene, graphene oxide, etc., have shown very strong potentials in terms of fundamental properties as well as advanced electronics and optical applications and hence have been the subject of huge research attention in the last couple of decades. Recent developments in the direction of 3D carbon based networked materials have opened many new avenues in the direction of electronics and optics fields. The research on metal oxide nanostructures based three dimensional interconnected ceramics networks is currently in the main focus because they can be utilized as unique backbone for developing hybrid nanomaterials. The nanostructures from inorganic, metal oxide and carbon, etc. materials can be easily integrated in form of hybrid 3D networks which involves new structure dependent electronic and optical features for advanced nanoelectronics and nanophotonics related applications.
Appropriate growth strategies of different confined nanostructures using simple methods, understanding their different properties, and applications of these pure and hybrid nanomaterials in the direction of nanoelectronics and nanophotonics are key fundamental issues to which this proposed symposium in EMRS Fall 2019 is going to briefly address. Researchers with interdisciplinary expertizes could easily help each other to realize the materials growth and corresponding structure-property relationships. In this proposal it is aimed to bring: (i) synthesis groups for developing different nanostructures, (ii) theoretical/modelling scientists, (iii) experts from electronics and photonics fields who can accordingly utilize these materials in various applications, together to develop a discussion platform with the theme ‘materials for nanoelectronics and nanophotonics’ at European Materials Society Fall meeting in 2019 in Warsaw, Poland. Over the last few years, halide perovskite nanocrystals have gained significant attentions from electronics and photonics aspects. They have been intensively explored for light emission and photovoltaic applications. Recent developments towards synthesis, theoretical and applications of these perovskite nanocrystals will also be covered in this symposium during EMRS Fall 19 in Warsaw.
Hot topics to be covered by the symposium:
- Hybrid nanomaterials: Synthesis, Characterizations, Structure-property relations, Analytical and simulation studies, Applications: Nanoelectronics, Sensing, Nanophotonics, Optics, Luminescent, etc.
- Nanoelectronics: Electronics, Sensing, Energy, Photovoltaics, Piezoelectric, Piezotronics, etc.
- Nanophotonics: Optics, Photonics, Plasmonics, Tera Hz optics, Luminescent, Waveguides, Whispering gallery modes, Light emitting diodes, Lasers, Imaging, Advanced lightening technologies, etc.
- Nano optoelectronics: UV and photodetection, Photovoltaics, Solar cells, Piezophototronics, etc.
List of invited speakers:
- Janas Dawid, Silesian University of Technology, Poland
- Neretina Svetlana, University of Notre Dame, USA
- Hughes Robert, University of Notre Dame, USA
- Spivak Yulia, Saint Petersburg State Electrotechnical University "LETI", Russia
- Goswami Sreetosh, NUS, Singapore
- Birowska Magdalena, University of Warsaw, Poland
- Mishra Shashank, Claude Bernard University of Lyon 1, France
- Rana Vikas, Forschungszentrum Jülich, Germany
- Pertsev Nikolay A., Ioffe Institute, St. Petersburg, Russia
Tentative list of scientific committee members:
- Rainer Adelung, Germany
- Franz Faupel, Kiel, Germany
- Lorenz Kienle, Germany
- Carsten Ronning, Germany
- Horst-Günter Rubahn, Denmark
- Jørgen Schou, Denmark
- Cordt Zollfrank, Germany
- Jörg Hübner, Denmark
- Ayodhya Nath Tiwari, Switzerland
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Plasmonics and Nanophotonics : Jost Adam, Yogendra Mishra
Authors : Svetlana Neretina, Robert Hughes, Spencer Golze, Sergei Rouvimov
Affiliations : University of Notre Dame, Notre Dame, IN, United States
Resume : The architectural diversity realized by plasmonic nanostructures is in large part due to seed-mediated colloidal growth modes that are seeded, not only by single-crystal seeds, but by seeds with a well-defined internal defect structure. Multi-twinned seeds have, for example, been used to generate colloids with icosahedral and decahedral structures while seeds with planar defects realize nanoplate geometries. Recently, we demonstrated a nanofabrication route that synergistically combines nanoimprint lithography, directed assembly, and liquid-phase epitaxy to obtain periodic arrays of complex noble metal nanostructures over a square centimeter area. This benchtop process leverages a synthetic strategy in which seed-mediated liquid-phase growth modes are carried out on substrate-immobilized seeds. While the strategy has led to the generation of substrate-based structures with considerable architectural diversity, it is fundamentally limited by the inability to fabricate seeds with the same internal defect structure as those routinely used in colloidal chemistry. Here, we demonstrate a large-area processing route for generating substrate-based Au seeds lined with stacking faults and use them to synthesize arrays of epitaxially aligned Au nanoplates using a plasmon-mediated growth mode. The work advances the possibility of bringing an exciting nanoplate chemistry to the substrate surface and, in doing so, provides the building blocks needed to enable on-chip plasmonic devices.
Authors : Elżbieta Karolina Sobolewska(1), Tomasz Kawalec(2), Horst-Günter Rubahn(1), Jost Adam(1), Jacek Fiutowski(1)
Affiliations : 1: Mads Clausen Institute, NanoSYD, University of Southern Denmark, Alsion 2, DK-6400 Sønderborg, Denmark; 2 Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. prof. Stanisława Łojasiewicza 11, 30-348 Krakow, Poland
Resume : Developing micro- and nano-scale systems with defined active elements acting as local sources of surface plasmons polaritons (SPPs) is crucial for future plasmonic circuitry. We demonstrate excitation of SPPs, exploiting fluorescent light from crystalline organic para-hexaphenylene nanofibers. The fibers were fabricated utilizing two scenarios, epitaxial growth on crystalline substrate and random growth directly on a metal surface. The excited SPPs are characterized using angle-resolved leakage radiation spectroscopy, in the excitation wavelength range 420 – 675 nm, corresponding to nanofibers photoluminescence band. To support experimental results, we developed a theoretical model based on finite-difference-time-domain (FDTD) method, where we introduced the excited nanofibers as polarized electric dipole sources on the dielectric/silver interface. We characterized the influence of the angular position of the dipoles to asymmetrical excitation of SPPs, which are related to fibre molecular alignment and possible changes due to the transfer process. These results were compared to LRS signals from randomly oriented p-6P nanofibers grown directly on Ag surface. Directly grown nanofibers reveal optical properties very similar to the transferred ones, while demonstrating polarization-insensitive plasmonic excitation and very good agreement with theoretical models. This opens a new way of integrating organic nanofibres into optoelectronic applications by direct deposition of the p-6P material onto desired substrates and avoids distortion of the fibre structure and introducing impurities during a transfer process.
Authors : Johannes Frueh, Julie Probst, Guangyu Qiu, Jing Wang
Affiliations : Harbin Institute of Technology, Institute of Micro- Nanotechnology research ETH Zürich, Institut für Umweltingeneurswissenschaften
Resume : Gold nanoparticles are ubiquitous in engineering, biological and medical research. The fluorescence of these particles is based on electrons which were excited from D band to above the Fermi level that fall back to the d-band. Fluorescence spectra are shown to be significantly influenced on the plasmon states and interparticle diameter. These excited electrons additionally strongly interact with surface chemicals, which influences the fluorescence spectra significantly. The dependence of the fluorescence intensity shows significant stochastical light intensity fluctuation over time in relation to different surface chemicals. These fluctuations are explained with electrons stochastically interacting with surface chemicals, compared to those falling back within the core of the particle. Potential uses of these effect are presented as well.
Authors : Alasdair AM Brown,[1,2,3] Xin Yu Chin, Thomas JN Hooper,[3,4] Parth Vashishtha, Annalisa Bruno,[c] Suan Hui Pu, Liudi Jiang, Ju Nie Tey, Bahulayan Damodaran,[c] Nripan Mathews,[3,4] and Subodh G. Mhaisalkar.[3,4]
Affiliations :  School of Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ;  Agency for Science and Technology Research (A*STAR) Singapore Institute of Manufacturing Technology (SIMTech), 73 Nanyang Drive, Singapore 637662;  Energy Research Institute at NTU (ERI@N), Research Techno Plaza, X-Frontier Block Level 5, 50 Nanyang Drive, Singapore 637553;  School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798;
Resume : Phosphonic acids have recently shown promise as surface-capping ligands for cesium lead bromide nanocrystals (CsPbBr3 NCs)[1,2]. The replacement of oleic acid with octylphosphonic acid in the CsPbBr3 NC synthesis has been found to provide significantly more robust passivation and polar solvent resistance . However, the mechanism behind this apparently tighter binding remains unexplained. It is crucial to understand the basis for tight ligand binding to all-inorganic perovskite NCs, in order to guide rational development of ligand system which can enable more stable, highly efficient LEDs. Through post-synthetic ligand exchange we reveal that octylphosphonates self-assemble in an extensive inter-ligand hydrogen-bonding network on the surface of CsPbBr3 NCs. We utilize 2D solid-state 31P−1H NMR, to demonstrate that octylphosphonate ligands bind preferentially in a monodentate mode through P−O−, leaving polar P=O and P−OH groups free to form inter-ligand hydrogen bonds. The strong passivation afforded by this ligand network yielded a purified CsPbBr3 NC ink with PLQY of 62 %, over 3 times higher than untreated NCs. This enabled highly-efficient LEDs, with maximum external quantum efficiency and luminance of 7.74 % and 1022 cd m-2 respectively, which is comparable with state-of-the-art all-inorganic perovskite NC LEDs. We anticipate that this self-assembled octylphosphonate passivation network could be beneficial across a breadth of halide perovskite optoelectronic applications.
Authors : Shigeru Kubota(a), Yoshiki Harada(a), Takenari Sudo(b), Kensaku Kanomata(a), Bashir Ahmmad(a), Jun Mizuno(b), and Fumihiko Hirose(a)
Affiliations : (a) Graduate School of Science and Engineering, Yamagata University, Japan, (b) Research Organization for Nano and Life Innovation, Waseda University, Japan
Resume : Organic photovoltaics (OPVs) are expected to be low-cost, flexible, and large-area power generation devices in the near future. OPVs are also suggested to be efficient indoor photovoltaic devices, because their fill factor is relatively high even for low light intensities. A key factor limiting the performance of OPVs is the fact that their active layer is as thin as ~100 nm, which makes it difficult to fully absorb incident light. To enhance the photocurrent generation, it is important to develop excellent light trapping technique adequate for OPVs. In this study, we propose an optical design of OPVs which can improve the refractive index profile within the device using high-refractive-index (high-n) glass substrate and nanotextured surface. We first numerically analyze the performance of various device configurations with changing the refractive index of the glass substrate. We show that the OPV performance is significantly improved by integrating the high-n glass substrate with the hybrid antireflection structure, which combines moth eye nanostructure and two-layer interference coating. We also show that the proposed device is effective to realize broad angle performance under both indoor and outdoor light sources and is robust against the variations in the geometric pattern of nanostructure. Finally, we experimentally measure the spectral dependence of photocurrent generation to verify the effectiveness of the proposed device design.
Authors : D.V. Yurasov, N.A. Baidakova, V.A. Verbus, N.S. Gusev, E.E. Morozova, A.V. Nezhdanov, E.V. Skorohodov, D.V. Shengurov, A.N. Yablonskiy and A.V. Novikiov
Affiliations : Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, Russia; National Research University Higher School of Economics, Nizhny Novgorod, Russia; Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603950, Russia
Resume : Germanium is the very attractive material for creation of Si-compatible light source due to full compatibility with CMOS technology and suitable direct-gap emission wavelength of 1.55 m. However due to indirect nature of Ge it emits light inefficiently. Application of tensile strain could lower the difference between direct and indirect gaps of Ge and even convert Ge to the direct semiconductor at high strains. Achievement of required strain levels in Ge is challenging for continuous films but such strains could be achieved in local areas of Ge film. In this work locally strained Ge structures of various geometries were fabricated using stress concentration approach [Nat. Photon. 7, 466 (2013)]. However this method leads to the formation of structures that are suspended in air which results in poor heat dissipation from them. In this work heat sink of such structures was significantly improved with the help of adhesion effect caused by capillary forces of liquid. Fabricated locally strained Ge microstructures have shown the nearly 10-fold enhancement of PL intensity along with the emission redshift which is accordance with theoretical predictions. These structures were embedded into micro-cavities of various types in order to ensure the confinement of light. Cavities based on Bragg reflectors and photonic crystals were implemented for such kind of active medium. Optical properties of tensile strained Ge microstructures embedded into such cavities were investigated.
Authors : Beatrice Roberta Bricchi, Luca Ornago, Cristina Mancarella, Matteo Ghidelli, Carlo S. Casari, Andrea Lucotti, Andrea Li Bassi
Affiliations : Beatrice Roberta Bricchi Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy; Luca Ornago Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy; Cristina Mancarella Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy; Matteo Ghidelli Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy; Carlo S. Casari Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy Center for Nanoscience and Technology – IIT@Polimi, via Giovanni Pascoli 70/3, 20133, Milano, Italy; Andrea Lucotti Department of Chemistry, Materials, and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy; Andrea Li Bassi Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133, Milano, Italy Center for Nanoscience and Technology – IIT@Polimi, via Giovanni Pascoli 70/3, 20133, Milano, Italy.
Resume : Transparent conductive oxides (TCOs) are doped oxides that have recently demonstrated tuneable optical properties from the visible to the mid-IR range, and are currently investigated both for the possibility to tune their plasmonic properties and to extend the application range of traditional plasmonic metallic materials. In this work, the synthesis of Tantalum-doped TiO2 (Ta:TiO2) thin films is performed via Pulsed Laser Deposition (PLD), enabling a fine control of the composition and nanostructure by changing the synthesis parameters. Specifically, the Ta content (5-10%) and oxygen stoichiometry have been varied, resulting in a fine control of the electrical, optical as well as plasmonic properties. In addition, we show that conductive ultrathin Ta:TiO2 films can be successfully obtained down to a thickness of 10 nm. We then investigate the integration of Au nanoparticles (NPs) in TCO films in different configurations, in order to tune the visible plasmonic frequency of Au NPs by changing the dielectric constant of the surrounding TCO matrix, which depends in turn on stoichiometry and nanoscale morphology. The plasmonic behavior of TCO films and Au NPs-integrated systems can thus be varied in the near-IR and visible range, respectively, by exploiting the carrier concentration control. The potential of this approach opens perspectives for the development of innovative optical metamaterials and active-modulated TCO-based plasmonic devices.
Authors : Dmitrii V. Shuleiko (1), Mikhail N. Martyshov (1), Danila V. Orlov (1), Stanislav V. Zabotnov (1), Denis E. Presnov (2,1), Andrey G. Kazanskii (1), Pavel K. Kashkarov (1)
Affiliations : (1) Lomonosov Moscow State University, Faculty of Physics, 1/2 Leninskie Gory, Moscow, 119991, Russia; (2) Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, 1/2 Leninskie Gory, Moscow, 119991, Russia
Resume : Modification of amorphous hydrogenated silicon (a-Si:H) by high-power femtosecond laser pulses allows to achieve anisotropy of their structural, electrical and optical properties due to formation of laser-induced periodic surface structures (LIPSS) . Such modified material can possess conductivity anisotropy  and dichroism , which can be used in thin-film photovoltaics and optoelectronics. In this work we experimentally observed formation of LIPSS with the period close to the wavelength of laser pulses (1250 nm). The orientation of such structures is parallel or perpendicular to the laser radiation polarization depending on the pulse number used during irradiation. According to the theoretical modeling , the observed structural changes were caused by different concentrations of nonequilibrium electrons excited by various numbers of high-power femtosecond laser pulses, which leads to variation of the dielectric constant real part of photoexcited a-Si:H film from negative to positive during the laser processing. The threshold values of the nonequilibrium electrons concentration required for turning the LIPSS direction were calculated. The work was supported by the Russian Foundation for Basic Research (project 19-32-70026).  Shuleiko D. V., Potemkin F. V., Romanov I. A., et al. Laser Phys. Lett. 15:056001 (2018)  R. Drevinskas, M. Beresna, M. Gecevičius, et al. Appl. Phys. Letters 106:171106 (2015)  J. Bonse, M. Munz, H. Sturm. J. Appl. Phys. 97:013538 (2005)
Authors : Manish Kumar1,2*, Marian Chapran3, L. Pereira1
Affiliations : 1 Department of Physics and i3N – Institute for Nanostructures, Nanomodulation and Nanofabrication, University of Aveiro, 3810-193 Aveiro, Portugal; 2 CeNTI – Centre for Nanotechnologies and Smart Materials, R. Fernando Mesquita, 2785, 4760-034 Vila Nova de Famalicão, Portugal; 3 Department of Molecular Physics, Technical University of Łódź, Żeromskiego 116, 90-924 Łódź, Poland
Resume : The efficiency of solution processed organic light emitting diodes is limited by the fabrication parameters such as thickness, spin-speed of organic layers and solvent. To investigate the solvent effectiveness, herein, we demonstrate the fabrication of highly efficient red-orange organic light emitting diodes based on thermally activated delayed fluorescence 2-[4-(diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA) emitters via solution processed. The devices were fabricated in a polymer host matrix with different wt.% of emitter in different solvents and their characteristics were studied. The device performance is compared with different solvents i.e. chlorobenzene, 1-2 dichlorobenzene, and chloroform. By optimizing the mixed ratio of EML, a solution processed, highly efficient, red-orange-emitting OLED of TXO-TPA TADF emitter fabricated with hole-transport layer (HTL) of poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS), which turn on a low voltage at 5V, with an excellent external quantum efficiency (ƞEQE) of 18%,%, current efficiency of 36.71 cd/A and power efficiency of 14.74 lm/W for the 8% emitter concentration. An explanation about the physical process is provided, considering both carrier injection/transport limits and involving the host: guest molecular interaction, as one the fundamental key for a successful device. AFM morphology of the thin film in different solvents also discussed to understand the molecular orientation for the efficient device. Further pathways to improve large area OLEDs efficiency are also discussed. Acknowledgments The authors are grateful for the financial support from the “EXCILIGHT” Project from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 674990
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Plasmonics and Nanophotonics : Jost Adam, Rosaria Puglisi
Authors : Andreas Seifert
Affiliations : CIC nanoGUNE Tolosa Hiribidea, 76, 20018 Donostia - San Sebastián, Spain
Resume : Plasmonic sensing, particularly plasmonic biosensing, has become an established method for rapid detection of biomolecules with low limit of detection and high sensitivity. Commercial instruments making use of surface plasmon resonances (SPR) are available within a very large price and performance range. In many cases, plasmonic resonances can be used as label-free technique for highly sensitive real-time sensing. Standard SPR instruments are operated in so-called Kretschmann configuration where the analyte or sample under test is in contact with a thin layer of a noble metal that is deposited on a dielectric. To match the dispersion conditions between exciting photons and sensing electrons, generally a dielectric prism or diffractive structures are used as coupling media. There is still no answer where the limits of plasmonic sensing are, since SPR as an integrated instrument includes many aspects more than merely the physical phenomenon of resonant coupling between light and electrical charges. Plasmonic sensing can be modified by introducing metallic nanostructures for generating localized surface plasmon resonances (LSPR). By using nanoparticles, similar and further localized phenomena can be introduced. The Nanoengineering Group at CIC nanoGUNE investigates improvements of plasmonic sensing techniques by utilizing metallic nanostructures, fabricated by electron-beam lithography, and by employing periodic arrays of self-assembled gold nanoparticles. Due to periodic structures, in both cases diffraction effects can be coupled with intrinsic plasmonic properties to enhance the signals by Rayleigh anomalies or Fano effects. Apart from introducing periodic structures, we demonstrate that Gaussian beam shaping improves the sensing performance, and sensitivity can be increased even more just by data analysis, by exploiting multiple features of the resonance curves via multivariate analysis methods. Looking at the method in a systemic way, as a fully integrated vehicle, further technological factors become decisive and help to improve the performance. Suitable biofunctionalization of the metal layer or particles will help to enhance sensitivity as well as specificity. In combination with microsystems engineering, multiplexing becomes possible for analyzing complex analytes in a single run. Optimized microfluidic platforms will help to minimize analyte volumes and allow for the determination of dynamic changes, resulting in better quantification. The ultimate goal of the presented research is the establishment of a fast and reliable liquid biopsy for the detection of various biomarkers, as for example exosomes, and the creation of a sensing platform for food quality control in terms of bacteria, toxicity, fraud, nutritional ingredients and maturity.
Authors : P. Gaffuri 1 2, M. Salaün 1, I. Gautier-Luneau 1, E.Appert 2, V.Consonni 2, A. Ibanez 1
Affiliations : 1 Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France 2 Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France.
Resume : White Light Emitting Diodes (wLEDs) recently dominated the lightning market due to their energy efficiency, stability, and easy integration into smart lighting technologies. However, the use of rare earth elements (Y, Ce…) in commercial phosphor-converted wLEDs raises environmental and geopolitical concerns, while their relatively narrow emission spectra require the use of several phosphors to obtain warm-white lightings. Recently, we synthetized yttrium-aluminum borate phosphors without any lanthanide as dopant using the polymeric precursor method 1. Their photoluminescence (PL) emission in the whole visible range arises from molecular clusters, trapped in a stable amorphous oxide matrix during the elaboration process. This was evidenced by coupling thermal analyses (DTA, thermogravimetry, mass spectrometry), PL spectroscopy, NMR and EPR measurements 2-3. Here we present our most recent works on the substitution of yttrium cations, initially introduced as glass matrix modifiers, by zinc cations. This new rare-earth-free phosphor produces broad and intense PL emissions when excited by near-UV LEDs, with high internal quantum yields (around 60%), and very good color rendering indexes (CRI > 90). Moreover, the PL emission is easily tunable in the visible, from warm- to cold-white light by simply adjusting the calcination temperature. Thus, these efficient and stable phosphors, only constituted by abundant and non-toxic elements opens the way for the development of rare-earth-free single phosphor LEDs for warm white lighting. 1 V. F. Guimarães et al., J. Mater. Chem. C, 2015, 3, 5795–5802. 2 P. Burner et al. Angew. Chemie - Int. Ed., 2017, 56, 13995–13998. 3 A. D. Sontakke et al. J. Phys. Chem. Lett., 2017, 8, 4735–4739.
Authors : Chukova O.1, Nedilko S.A.1, Nedilko S.G.1, Slepets A.1, Voitenko T.1, Androulidaki M.2, Manousa A.2, Papadopoulos A.2, Savva K.2, Stratakis E.2
Affiliations : 1 - Taras Shevchenko National University of Kyiv, Volodymyrska Str., 64/13, Kyiv 01601, Ukraine. E-mail: firstname.lastname@example.org; 2 - Institute of Electronic Structure & Laser (IESL) of Foundation for Research & Technology Hellas (FORTH), Heraklion 711 10 Crete, Greece
Resume : A wide range of possible applications of vanadate nanoparticles have attracted significant research efforts to development of new vanadate compositions with improved characteristics depending on requirements of various practical tasks. Study of the Eu3 -activated LaVO4 vanadate nanoparticles, has revealed increase of emission intensity in 10 times under some conditions. Also we have developed vanadate nanoparticles with enchanced light harvesting from violet spectral range using heterovalence substitutions of RE ions. The next important task is to to save the obtained high optical characteristics of nanoparticles under their deposition onto various substrates. In the present work we report results of experiments on deposition of thin films with vanadate nanoparticles on glass and silicon substrates. The films were applied by three different methods and compared. There are pulsed laser deposition, spin-coating and chemical drop evaporation methods. Morphology of the films was studied using optical, atomic force and scanning electron microscopy. It was shown that films made from the same compositions but under different procedures possess different morphology. Influence of procedure on structure and luminescence characteristics of films has been discussed. This work has received funding from Ministry of Education and Science of Ukraine and from the EU-H2020 grant No 654360 within the framework of the NFFA-Europe Transnational Access Activity.
Authors : K N Prajapati1, K Bandopadhyay2, and J. Mitra1
Affiliations : 1School of Physics, IISER Thiruvananthapuram, Kerala 695551, India 2 Institute of Electronic Materials Technology (ITME), Warsaw, Poland
Resume : Rational design of hybrid nanostructures by incorporating semiconducting nanorods with metal nanoparticles (NPs) and quantum dots (QDs) has proven a useful way to tune their existing functionalities, even elicit newer response (1, 2). Here we explored the emission properties of hybrids of ZnO nanorods with plasmonic metal (Au/Ag) NPs and semiconducting (CdSe) QDs. The NPs and QDs having absorption resonances between 430-550 nm. Results show that attaching metal NPs to ZnO selectively enhances the latter’s band-edge luminescence while quenching the visible emission (associated with the defect states). This selective band-edge enhancement mechanism can be understood by the plasmon-exciton, plexcitonic interaction in the hybrid (3). For QD-ZnO hybrids though ZnO’s band-edge emission enhances or quenches depending on the position of conduction band edge of the QDs used, which dictate the nature of the ZnO-CdSe junction. Thus even though the NPs and the QDs both show absorption resonances within 100 nm, the resulting excited state interacts with ZnO very differently which stems from the collective excitation nature of the plasmons in the metal NPs and dominantly single electron excitation in the QDs – the physics of which is discussed in this investigation. Finally we showcase a novel application of the Au NP–ZnO nanorods hybrid system to design a hierarchical surface enhanced Raman spectroscopy substrate where ZnO nanorods grown selectively on micron-scale hexagonal patterned substrates are decorated with Au NPs. This disordered system not only enhances Raman signal of rhodamine blue and fluorescein making them detectable in nanomolar concentrations but further does so selectively at the ZnO nanorod sites restricting the enhancement to the hexagonally patterned region. This spatial segregation of Raman activity within a predesignated pattern then paves the way for obtaining Raman microscopy images forging a new route for Raman analysis. References 1. Lee M-K, Kim TG, Kim W, Sung Y-M. Surface Plasmon Resonance (SPR) Electron and Energy Transfer in Noble Metal−Zinc Oxide Composite Nanocrystals. The Journal of Physical Chemistry C. 2008;112(27):10079-82. 2. Eley C, Li T, Liao F, Fairclough SM, Smith JM, Smith G, et al. Nanojunction‐Mediated Photocatalytic Enhancement in Heterostructured CdS/ZnO, CdSe/ZnO, and CdTe/ZnO Nanocrystals. Angewandte Chemie International Edition. 2014;53(30):7838-42. 3. Sun J, Hu H, Zheng D, Zhang D, Deng Q, Zhang S, et al. Light-Emitting Plexciton: Exploiting Plasmon-Exciton Interaction in the Intermediate Coupling Regime. ACS Nano. 2018;12(10):10393-402.
Authors : Bartosz Janaszek, Marcin Kieliszczyk, Paweł Szczepański
Affiliations : Warsaw University of Technology; Warsaw University of Technology; Warsaw University of Technology, National Institute of Communication
Resume : The concept of constructing functional structures at subatomic level has brought new avenues in shaping macroscopic response at will. One of the most promising class of structures in terms of tailoring electromagnetic response are so called metamaterials. In particular, hyperbolic metamaterials (HMMs), a special class of metamaterials revealing extreme anisotropy, has gather a lot attention, due to their unique properties and potentially high feasibility Hyperbolic metamaterials have already proven their usability in terms of sensing, imaging, waveguiding and quantum engineering. Quoted applications, as well as many others, are consequence of unclosed surface in wavevector space, known as hyperbolic dispersion. In this work, we present properties of hyperbolic metamaterials arising from effective nonlocality of the structure. By combination of various analytical and numerical methods, we explore capabilities of HMMs within range of extremely high values of wave vector. In particular, our efforts are dedicated to exploiting and tailoring electromagnetic response of nonlocal hyperbolic metamaterial for passive and active optical components.
Authors : V.Yu.Timoshenko (a,c,d), S.P. Rodichkina (a,b), A. I. Efimova (a), E.A. Lipkova (a), A.A.Eliseev (a), L.A.Golovan (a), A.V. Pavlikov (a), T. Nychyporuk (b), V. Lysenko(b,c)
Affiliations : (a) Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (b)University of Lyon, INSA de Lyon, INL, UMR CNRS 5270, Lyon, France; (c) National Research Nuclear University MEPhI, Kashirskoye Sh. 31, 115409 Moscow, Russia; (d)Lebedev Physical Institute of RAS, Leninskiy Prospekt 53, 119991 Moscow, Russia
Resume : Silicon nanowires (SiNWs) are promising for photonics, optoelectronics, thermoelectric and sensor applications, which require fast and convenient methods to control and monitor the electrical properties of SiNWs. However, the standard approach based on electrical contact measurements is hardly applicable to SiNWs prepared by wet chemical approach due to their complex morphology and heterogeneity. In contrast to the electrical methods, the optical spectroscopy is contactless and can be applied to nanostructures of different morphologies. In this work we propose to determine the free charge carrier concentration in SiNWs of p- and n-type by using the Raman scattering and Fourier transform infrared (FTIR) spectroscopy in attenuated total reflection (ATR) mode. By means of the Raman and FTIR-ATR diagnostics we determine the free carrier concentration in SiNWs fabricated by metal-assisted chemical etching of c-Si wafers followed by additional doping with Boron and Phosphorous impurities via thermal stimulated diffusion. The carrier concentrations in doped SiNWs are found to be of the order of 10^18…10^20 cm-3 for different preparation conditions. The developed optical methods of charge carrier diagnostics seem to be easily incorporated into technologies of fabrication of doped SiNWs for various applications.
Plasmonics and Nanophotonics : Jacek Fiutowski, Svetlana Neretina
Authors : Robert Hughes, Arin Preston, and Svetlana Neretina
Affiliations : University of Notre Dame, Notre Dame, IN, United States
Resume : The stability and durability of plasmonic materials is a subject of fundamental importance that can decide whether a technology is viable, reliable, and sustainable. Such considerations become amplified for plasmonic applications requiring that the nanostructures operate at elevated temperatures. With plasmonics being a field of study that is powered by the ability to shape- and size-engineer metals at the nanoscale, the tendency for these same structures to oxidize and morphologically reconfigure when heated can disrupt or destroy properties that were so carefully engineered in the first place. Here, we report on a strategy capable of yielding substrate-based plasmonic nanostructures that are robust to oxidation, etchants, and high temperatures. It is reliant on the formation of substrate-immobilized single-crystal nanostructures to which an ultrathin protective cladding is applied. It will be shown that suitably clad Au structures with far from equilibrium geometries are able to maintain their shape at temperatures as high as 800 °C. Using the same cladding, Cu structures are resistant to oxidation in air at temperatures as high as 600 °C. In both cases, the plasmonic properties, while modified by the application of the cladding, remain unchanged when heated. Together, the work provides a fundamental understanding of high-temperature diffusion processes occurring for clad metals and advances the processing science needed to manufacture durable plasmonics.
Authors : F. Ruffino, R. Grillo, V. Torrisi, M. Zimbone, M. G. Grimaldi
Affiliations : F. Ruffino, R. Grillo, V. Torrisi, M. Zimbone, M. G. Grimaldi Dipartimento di Fisica ed Astronomia "Ettore Majorana"-Università di Catania, via S. Sofia 64, 95123 Catania, Italy and IMM-CNR, via S. Sofia 64, 95123 Catania, Italy M. Zimbone IMM-CNR, via S. Sofia 64, 95123 Catania, Italy V. Torrisi BRIT (Bio-nanotech Research Innovation Tower), Università di Catania, via S. Sofia 89, 95123 Catania, Italy
Resume : Nanoporous Au attracts great technological interest as a promising candidate for optical and electrochemical sensors. The present literature is focused on fabrication, characterization, and application of nanoporous Au leafs and films. Recently, however, interest was attracted by nanoporous Au micro- and nano-structures due to much higher surface-to-volume ratio. In this work we report on the development of simple, versatile, cost-effective approaches for the production of nanoporous Au micro- and nano-structures directly on surfaces. The following procedures were developed: nanoscale-thick Au/Ag bilayers were deposited on SiO2 or FTO substrates; then, the alloying and dewetting processes of the bilayers were induced by furnace annealing of the bilayers on SiO2 or by nanosecond-pulsed laser irradiations of the bilayers on FTO. The alloying and dewetting processes were observed to result in the formation of AuxAgy alloy sub-micron particles; finally, the AuxAgy alloy particles were dealloyed in HNO3 solution to selectively etch Ag resulting in the formation of nanoporous Au particles. We discuss on: a) the dependence of size and shape of the particles on the dewetting process (solid-state on SiO2, molten-state on FTO); b) the dependence of particles porosity on the typology of the alloying process (32% for the solid-state and 45% for molten-state dewetted particles). Perspectives on the exploitation of these systems in plasmonic-based sensors are, finally, outlined.
Authors : Mathias Charconnet,a,b Cristiano Matricardi,c Agustín Mihi,c Jost Adam,d Luis M. Liz-Marzánb,e and Andreas Seiferta,e
Affiliations : a CIC nanoGUNE, Nanoengineering Group, Donostia-San Sebastián, Spain b CIC biomaGUNE, Bionanoplasmonics Laboratory, Donostia-San Sebastián, Spain c Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Nanooptener Group, Bellaterra, Spain d University of Southern Denmark, Mads Clausen Institute, Sønderborg , Denmark e IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
Resume : Metallic nanoparticles (NPs) are known for their plasmonic properties allowing them to confine electric fields to nanometric volumes. The strong confinement of the electric field creates very large electric fields in close proximity of the NP, also known as hotspots. The size, shape and material of the NP specifically defines the wavelength, at which light is absorbed due to interaction with the metal electrons, and hence, the properties of the electric field enhancement. One way to increase the absorption of NPs is to create periodic structures. These periodic structures feature so-called Rayleigh anomalies, which occur when the incident light is diffracted in-plane. The diffraction follows the well-known grating equation that depends on the wavelength and lattice period. The diffracted waves can either propagate in the substrate or in the superstrate, thereby increasing the interaction of light with the nanoparticles at the interface. If the lattice NPs comprise a plasmonic resonance at the Rayleigh anomaly wavelength, their absorption increases remarkably, giving rise to so-called lattice plasmons. Generally, periodic nanostructures featuring lattice plasmons are fabricated by electron beam lithography. Our strategy, however, consists of a bottom-up approach for creating periodic structures of gold nanoparticles. We present here a process for capillary-assisted self-assembly of differently shaped NPs into superlattices.
Authors : Viraj Bhingardive1,3, Avichai Marcovici1,3, Guillaume Le Saux1,3, Pazit Rukenstein2,3, Kobi Flomin2,3, Karam shreteh2,3, Taleb Mokari2,3, Mark Schvartzman1,3
Affiliations : 1 Department of Materials Engineering, 2 Department of Chemistry, 3 Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel
Resume : One dimensional semiconductor (1D) nanomaterials are promising building blocks for future nanodevices and nanosystems. Yet, controlled and uniform assembly of these 1D nanostructure with precise location and orientation is still a major challenge towards their integration into functional nano scale devices. To address this challenge, Mokari et al reported synthesis of semiconductor nanorods with metallic tips, which can serve as natural anchors. However, the concept of controlled assembly of metal-tipped nanorods has been unexplored since then. Recently, we demonstrated controlled assembly of Au tipped CdS nanorods (nanodumbbells) onto nanopatterned anchoring functionalities. The functionalities are made of nanoimprinted Au nanodots with immobilized thiol molecules. Here, we report detailed mechanism of Au-CdS-Au nanodumbbell assembly, by demonstrating two types of nanodumbbell anchoring. In the first type, one nanodumbbell anchors to one functionalized dot. In this case, many neighboring nanodumbbells are connected to each other with their free edges, either by side-by-side parallel connection due to antiparallel coupling between permanent dipole moments along the rod axis or van der Waals forces, or by end-to-end connection due to solvent evaporation. In the second type, a nanodumbbell is anchored to a pair of nanodots whose spacing matches the nanodumbbell length. Also, we used AFM to find that the anchored nanodumbbells, while chemically attached to the nanodots, lay on the surface, and are not suspended. Finally, we have studied the effect of assembly time and different solvents with various polarities on the assembly process. Our study provides an important insight onto the fundamental mechanism of the controlled assembly at the nanometer scale, and opens a pathway to the bottom-up realization of nanosystems with a structural and functional complexity unachievable nowadays.
Authors : K. Rubešová, D. Mikolášová, J. Havlíček, T. Hlásek, V. Jakeš, P. Nekvindová, R. Kučerková, M. Nikl, J. Oswald
Affiliations : Department of Inorganic Chemistry, University of Chemistry and Technology, Technicka 5, 166 28 Prague 6, Czech Republic (K. Rubešová; D. Mikolášová; J. Havlíček; T. Hlásek; V. Jakeš; P. Nekvindová) Institute of Physics of the Czech Academy of Sciences, Cukrovarnicka 10, 16200 Prague, Czech Republic (R. Kučerková; M. Nikl; J. Oswald)
Resume : Thin films are a special group of materials applicable in optical, optoelectronic or sensor technology. Apart from vacuum-requiring techniques (PLD, CVD etc.) and the growth from melt (LPE), there are solution-based methods that are advantageous especially in the stage of research of new materials. To keep the benefit of a cheap and easy feasible method, the homogeneity of films with sufficient microstructure (low porosity and surface roughness) must be ensured. In the case of sol-gel methods, problems appear when multi-cation oxides are prepared. The different rate of hydrolysis and/or behaviour with the pH change can be a complication. Another challenge occurs when oxides contain a cation of a high valence - to stabilize such a cation in a water solution is not an easy task. In this presentation, thin films prepared by a sol-gel based method utilizing spin-coating will be presented. We have used water-soluble polymers (polyethyleneglycol, polyvinylpyrrolidone) to stabilize present cations; two group of materials have been deposited - Er3 /Yb3 doped oxides and Ce3 doped garnet structures. The erbium doped thin films are applicable as optical waveguides, so thin films not only with appropriate photoluminescence properties but also with sufficient microstructure had to be prepared. In the latter case, homogeneous thin films of YAG with a high concentration of Ce will be presented. Such films are applicable in scintillator technology - especially in scintillation imaging.
|15:30||Coffee / Tea Break|
Nanomaterials and Memory Devices : Yogendra Mishra, Jean-Claude Grivel
Authors : Sreetosh Goswami, T. Venkatesan
Affiliations : National University of Singapore, National University of Singapore
Resume : Handling ‘big data’ demands major technological breakthroughs in computing and storage that can provide high data density with reduced power dissipation. ‘Mem-elements’ such as memristors and memcapacitors could enable this. However, while the last decade has seen an explosion in publications on memristive devices, experimental observations, and mathematical theorems demonstrate that non-volatile memristors have continuous conductance states, optimal for emerging analog, but not digital computing. Digital electronics constitutes the backbone of modern computing and is likely to remain so for the foreseeable future. Hence, successful implementation of emerging technologies like artificial intelligence and the internet of things in existing computing platforms demands the invention of devices that can enable multi-state, energy-efficient digital computing. In this presentation, I will talk about a memristor with three discrete conductance states using a film of a Ru-complex with an azo-aromatic ligand. Electric-field driven transitions between three different molecular redox-states yield three conductance plateaus that are non-volatile, robust (from 173-773K), functionally stable (>10^5s), enduring (>10^10cycles) with fast and sharp transitions (switching time <30ns, <5mV/decade) consuming very little energy (~200aJ) – optimal for high-density and energy efficient digital computing. Our device concurrently exhibits a binary memcapacitance, facilitated by a field-driven electronic symmetry breaking in our film. The electronic ground state of the film is characterized by charge disproportionation (CD), the formation and disruption of which is determined by a field-controlled displacement of counterions w.r.t. the organo-metallic molecules. Fundamentally, our results offer two significant advances: first, without violating the mathematical framework of memristors, we show that non-volatile memristive states can be functionally discrete and so memristors can be optimally designed for multi-state digital platforms and secondly, in contrast to its usual condition specific occurrences, by achieving CD at ambient conditions using an applied field, we achieve a long-sought goal in condensed matter physics providing an unprecedented material route to design a discrete memcapacitor. Ref: 1. Goswami, Sreetosh, et al. "Robust resistive memory devices using solution-processable metal-coordinated azo aromatics." Nature materials 16.12 (2017): 1216. 2. Valov, Ilia, and Michael Kozicki. "Non-volatile memories: Organic memristors come of age." Nature materials 16.12 (2017): 1170.
Authors : L. Prazakova, E. Nolot, E. Martinez, D. Morel, N. Rochat, D. Rouchon, C. Sabbione, M. Bernard, M. C. Cyrille, G. Navarro
Affiliations : CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
Resume : Phase-Change Memory (PCM) is considered the most mature among the emerging Non‑Volatile Memory technologies. Indeed, optimized Ge‑rich Ge‑Sb‑Te (GST) phase‑change materials proved their compliance with the strict reliability requirements at high temperature demanded by automotive applications . Recently, it has been reported that N‑doping in Ge-rich alloys can enable a further improvement of the device reliability performances [2, 3]. However, a structural evaluation of N‑doped Ge‑rich GST system and the understanding of the bonding rearrangement followed by N addition in this alloy remain a big challenge. Thanks to physicochemical characterization, in particular Infrared and Raman spectroscopy, we investigate the interaction between N and Ge‑rich GST compound by comparing the spectra of undoped and doped samples, considering also single elements analyses. Moreover, the structural evolution of the compound at high temperature, moving towards the material crystallization, is highlighted by significant changes of the spectra.  P. Zuliani et al., IMW 2019.  H. Y. Cheng et al., IEDM 2012.  G. Navarro et al, IMW 2016.
Authors : Cara-Lena Nies, Suresh Kondati Natarajan, Michael Nolan
Affiliations : Tyndall National Institute, UCC, T12 R5CP Cork, Ireland
Resume : With ever decreasing transistor size, materials that combine both diffusion barrier and liner material properties are needed to successfully electroplate Cu and thus beat the current interconnect bottleneck. In order to facilitate coating of high aspect ratio vias, the material should be as thin as possible. One possibility to achieve this is presented in this study, where we investigate through density functional theory, the behavior of Cu on Ru-doped and Ru passivated ε-TaN (1 1 0). Initially, the adsorption, diffusion and association of one and two Cu atoms on the different surfaces was studied in order to probe the early stages of film growth. This showed that, while surface diffusion of atoms was more favourable on the Ru-passivated surface, the Ru dopant acts as a nucleation site for Cu, with atoms preferentially diffusing towards it. In order to understand the mechanism of film growth on this surface in more detail and to fine-tune the barrier and liner properties of the material, the effect of different percentages of TaN surface doping with Ru were studied. Further, the behavior of Cu13 and Cu29 structures on different doped surfaces and on the passivated surfaces was investigated. In particular, the study focused on the pathways toward agglomeration as well as the associated activation energies. We find that on a Ru doped surface the atoms agglomerate spontaneously to form a two-layer film, whereas they remain in a monolayer on Ru-passivated TaN (1 1 0).
Authors : Jianbo Sun, Alessandro Grillo, Maurizio Passacantando, Antonio Di Bartolomeo, Jose Caridad and Luca Camilli
Affiliations : Department of Physics, Technical University of Denmark; Department of Physics, University of Salerno; Department of Physical and Chemical Sciences, University of L'Aquila; Department of Physics, University of Salerno; Department of Physics, Technical University of Denmark; Department of Physics, Technical University of Denmark;
Resume : Group IV-V compound two-dimensional materials, such as germanium phosphide (GeP), germanium arsenide (GeAs) and silicon arsenide (SiAs), are promising to enable novel electronics and optoelectronics in light of their strong in-plane electrical and optical anisotropy , . Here we present a systematic study on the carrier transport behavior of few-layer GeAs. The temperature-dependent conductivity exhibits a transition between thermal activation at high temperatures and variable range hopping (VRH) at low temperatures, which implies the presence of the abundant localized states along the channel. The extracted carrier mobility is around 10 cm2V-1s-1 at room temperature and decreases as the temperature decreases, which suggests that the carrier transport is dominated by the ionized impurity scattering. Interestingly, these localized states could serve as recombination center, as evidenced by the abnormal decreasing of the carrier concentration as a function of the temperature from 80 K to 200K. The carrier transport behavior of GeAs in magnetic field was also studied. These data will be useful for designing new devices based on these novel group IV-V compound 2D materials. Reference:  J. Guo et al., Adv. Mater., vol. 30, no. 21, pp. 1–6, 2018.  S. Yang et al., Adv. Funct. Mater., vol. 28, no. 16, pp. 1–10, 2018.
Authors : Daniele Spucches, Sebastiano Caccamo, Enza Fazio, Fortunato Neri, Giovanni Mannino, Silvia Scalese, Antonino La Magna, Rosaria A. Puglisi
Affiliations : CNR Institute for Microelectronics and Microsystems Strada VIII n.5, Zona industriale, 95121 Catania, Italy; Dipartimento Scienze Matematiche ed Informatiche, Scienze Fisiche e Scienze della Terra, Università degli Studi di Messina, F. Stagno d’Alcontres, 31, 98166 Messina, Italy
Resume : Silicon nanowires (SiNWs) represent the subject of an extensive literature thanks to their exceptional physical properties, such as for example quantum confinement effects. These are expected when the SiNWs mean diameter is less than the size of free exciton (the Bohr radius of about 5 nm) of bulk silicon. The synthesis of NWs with diameters in this range of size represents a considerable technological challenge. One common approach to synthesize SiNWs is based on the metal-induced chemical etching. Even if this method allows to obtain very small SiNWs, however they present high surface roughness with consequent surface recombination effects of the electrical carriers. Furthermore, it is not easy to implement this synthesis technique within the production lines because it is based on methods and instruments that are not currently present in the industries. Other approaches propose the possibility of oxidizing SiNWs obtained by more standard methods. In this case, the oxidation process consumes silicon, making the SiNWs thinner. However, this approach has several disadvantages such as the formation of a rough and defective surface and local defects in the crystalline structure. In this paper, we present the possibility to synthesize small SiNWs down to 5 nm in diameter, through chemical vapor deposition (CVD), a controlled technique already present in the semiconductor industries. The growth is induced by nanostructures working as catalysts. By an appropriate modulation of the surface tension obtained by changing the CVD chamber pressure, it is possible to find the favourable thermodynamic conditions for the nucleation of nanostructures as small as 5 nm in diameter.
Poster Session : Jost Adam, Jean-Claude Grivel, Yogendra Mishra, Rosaria Puglisi
Authors : Yatao Zou, Baoquan Sun*
Affiliations : Institution of Functional Nano & Soft Materials, Soochow University, China
Resume : Organometal halide perovskites (OHP) are promising materials for low-cost, high-efficiency light-emitting diodes. In films with a distribution of two-dimensional OHP nanosheets and small three-dimensional nanocrystals, an energy funnel can be realized that concentrates the excitations in highly efficient radiative recombination centers. However, this energy funnel is likely to contain inefficient pathways as the size distribution of nanocrystals, the phase separation between the OHP and the organic phase. In addtion, inbalanced charge carrier injection in light emitting diodes (LEDs) could decrease the radiative recombiantion, which is one of the main challenge to further improve the efficiency and stability of perovskite LEDs. Here, we demonstrate that the OHP crystallite distribution and phase separation can be precisely controlled by adding a molecule that suppresses crystallization of the organic phase. We use these improved material properties along with an optimized devcie structure to achieve OHP light-emitting diodes with an external quantum efficiency of 15.5%. Our results demonstrate that through the addition of judiciously selected molecular additives, sufficient carrier confinement with first-order recombination characteristics, and efficient suppression of non-radiative recombination can be achieved while retaining efficient charge transport characteristics.
Authors : Myungwoo Son, Moon-Ho Ham
Affiliations : Photonic Energy Research Center, Korea Photonics Technology Institute, Gwangju, 61007, Republic of Korea; School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
Resume : There is significant interest in synthesizing large-area graphene films at low temperatures by chemical vapor deposition (CVD) for nanoelectronic and flexible device applications. In addition, the modulation of electronic properties of graphene is of great technological importance and can be achieved by Fermi level shift by electron acceptor/donor doping. For practical applications, substitution of carbon atoms with other atoms, e.g. nitrogen, in graphene is one of the most suitable doping methods in terms of doping stability. However, this typically involves high-temperature growth or annealing processes in the presence of nitrogen sources such as ammonia because substitutional doping is related to covalent bonding. In this study, we demonstrate a two-step chemical vapor deposition technique for the production of continuous nitrogen-doped graphene films from pyridine at low temperatures under ambient pressure. In this method, we added the second growth step with higher carbon concentration for facilitating lateral growth of graphene. This led to continuous nitrogen-doped graphene films with full surface coverage and excellent quality.
Authors : P.V. Galiy1, T.M. Nenchuk1, A. Ciszewski2, P. Mazur2, O.R. Dveriy3
Affiliations : 1 Electronics and Computer Technology Dept., Ivan Franko Lviv National University, Lviv, Ukraine; 2 Institute of Experimental Physics, University of Wroclaw, Wroclaw, Poland; 3 Chair of Electromechanics and Electronics, National Academy of Land Forces, Lviv, Ukraine
Resume : In4Se3 as two-dimensional van der Waals semiconductor is a promising material for novel functional device applications. Particularly, transition metal trichalcogenides, like MX3 (M=Ti, Zr, Hf; X=S, Se, Te) and In4X3 (X=Se, Te), are possible candidates for a semiconductor channel with high carriers mobility of a field effect transistor on the nanoscale. In4Se3 crystal is also a suitable material for thermoelectric applications related to its two-dimensionality. The surface of these crystals have suggested no indication of surface reconstruction and thus is an ideal natural topographical template for nanosystems self assembling. Our work covers some scientific and technological aspects related to the material properties of In4Se3 layered semiconductor and formation of deposited indium nanostructures onto its 2D surface, such as nanodots and nanowires, in the view of directed self-assembly of ordered metallic structures. Thus obtained metallic nanoobjects on 2D semiconductor might be useful for nanoelectronics through their integration in various functional devices. In this case the precise control of such parameters of nanostructures as shape and size and, what is the most critical for nanoelectronics, the feasibility to form ordered arrays of metallic 0D and 1D structures on semiconductor substrate are essential.
Authors : Jukwan Na, Jun Shik Choi, Juyoung Kwon, Yong-beom Lim, Heon-Jin Choi
Affiliations : Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, South Korea
Resume : The research area of a biosensor for self-healthcare has been expanded, then the various type of biosensors has been invented and the market of a biosensor also has been grown accordingly. On the wearable biosensor area, the developed biosensors are only able to detect physical changes of a body or few of physiological ions from the sweat and tears. However, disease markers such as biomolecules and heavy metal ions are contained in the blood. Therefore, disease markers in blood should be detected by a new type of advanced biosensor for early-diagnosis of diseases with self-healthcare. Herein, we reported a 3D Si micropillar array (SiMPA) called a 3D hybrid device which is designed invasive type to puncture the skin and detect disease markers in blood without a skin incision. The DRIE (Deep Reactive-Ion Etching), wet etch and CMOS (Complementary Metal-Oxide Semiconductor) process was applied to fabricate SiMPA. The DRIE process was used to make SiMPA with a height of 600 μm on the Si substrate. After that, SiMPA were etched by KOH solution to be sharpened after the DRIE process. Finally, the CMOS process was applied to construct an electrical circuit that made each pillar work as an individual electrode. The surface electrode of SiMPA was coated with peptides that can selectively and sensitively bind with disease markers for real-time diagnosis and prevention of disease. The 3D hybrid device was connected to flexible-PCB (printed circuit board) and PCB to minimize noise and to contact the skin easier. The performance test of the 3D hybrid device was carried out by 1.optimization of the circuit of the device (we called “comprehensive circuit”), 2.in-vitro test to confirm the performance of the device in the human blood serum, and 3.in-vivo test to verify the feasibility of the device in the blood circulation system. The results of the in-vitro and in-vivo test showed the change of circuit by peptides which bound with disease markers. The in-vivo test was progressed by intravascular injection of disease markers with placed the device on the skin, as a result, the 3D hybrid device was verified its feasibility that it can detect disease marker in the real blood circulation system on the skin. This 3D hybrid device showed it can be used as a new type of platform as a real-time wearable biosensor with high sensitivity and high selectivity.
Authors : Li Zheng, Wen Zhou, Wenjia Zhou, Zhijun Ning, Xinhong Cheng, Yuehui. Yu
Affiliations : 1. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China 2. School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
Resume : N, S co-decorated graphene integrated with PbS colloidal quantum dots (CQDs) has been performed to fabricate a hybrid phototransistor. It demonstrates a gate-tunable ambipolar feature with a low gate bias of less than 3.3 V at room temperature in ambient. Broadband spectra from visible to short wave infrared (SWIR) light can be detected with ultrahigh gain value of 1e5 and fast response of 3 ms. Upon SWIR light at 1550 nm, the phototransistor exhibits ultrahigh responsibility (1e4 A/W) and specific detectivity (1e12 Jones) with a low driving voltage of 1 V. This decorated hybrid architecture illustrates the potential of graphene and CQDs to be integrated with silicon integrated circuits and open new path for ambipolar photodetectors fabrications.
Authors : Dong-Hwan Jun, Dong Hak Kim, Junhyun Kang, Jin Dong Song, and Il Ki Han
Affiliations : Korea Advanced Nano Fab Center, 109, Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16229, Korea; Korea Advanced Nano Fab Center, 109, Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16229, Korea; Korea Institute of Science and Technology, 5 Hwarang-ro, 14-gil, Seongbuk-gu, Seoul, 136-791, Korea; Korea Institute of Science and Technology, 5 Hwarang-ro, 14-gil, Seongbuk-gu, Seoul, 136-791, Korea; Korea Institute of Science and Technology, 5 Hwarang-ro, 14-gil, Seongbuk-gu, Seoul, 136-791, Korea;
Resume : One of the most beneficial material for infrared quantum cascade lasers (QCLs) is InGaAs/InAlAs due to the large conduction band offsets which minimizes the leakage current of QCLs and enables room temperature operations. Increasing(decreasing) the In mole fractions of InGaAs(InAlAs) layer enables increment of the conduction band offsets, thereby the loss of thermal effect of the QCLs could be still more minimized. On the contrary, the In mole fraction of InGaAs(InAlAs) also changes the lattice constants of each layers and leads to lattice mismatch between InP and the core layers; it usually incurs strain and strain induced defects. Therefore, in order to minimize the strain, symmetric In mole fraction for InGaAs and InAlAs have been generally designed and fabricated. However, significant strains could be remained because of the asymmetric thicknesses of InGaAs and InAlAs layers and strain induced defects could be incurred; thus characteristics of QCLs could be degraded. We proposed and fabricated QCLs having 55%-asymmetric InGaAs/InAlAs structures which could compensate the effect of asymmetric thicknesses of InGaAs and InAlAs layers and thereby strain induced defects could be effectively minimized. Characteristics of the fabricated asymmetric InGaAs/InAlAs QCLs were compared with those of fabricated lattice matched QCLs. Characteristics of the lattice matched and strained QCLs having the double channel waveguide structures were measured. It should be noted that the asymmetric strained QCL exhibited very robust temperature dependent wavelength characteristics compared with those of the lattice matched QCLs. Detailed structures and characteristics will be presented. Acknowledgement: This work was supported by the technology Innovation Program (10077700 and 10053010) funded by the Ministry of Trade industry & Energy(MI, Korea).
Authors : Madhav Kumar1*, Praveen Kumar2 and Harish Bhaskaran3
Affiliations : 1) Université Grenoble Alpes, CEA, LETI, 38000 Grenoble, France. (madhav.KUMAR@cea.fr); 2) Université Grenoble Alpes, INAC-MEM-LEMMA, CEA, 38000 Grenoble, France 3) Department of Materials, University of Oxford, Oxford, United Kingdom
Resume : Mono-atomic thick layer graphene being extremely stiff and low mass makes it an ideal candidate for Nanoelectromechanical systems (NEMS). In the past two decades, extensive research has been done to exploit its electromechanical properties. However, it has been extremely challenging to fabricate graphene-based resonator such as a cantilever and multiple clamped suspended structures (to reduce the clamping area). Here, we report the fabrication and characterization of various monolayer suspended graphene structure such as free-standing cantilever, folded and other suspended beam which has been extremely difficult to fabricate. We have used electron beam lithography and plasma etching process to design our structure. To release the graphene structure, we use hydrofluoric acid etchant followed by critical point drying process to avoid suspended structure being collapsed. We have also observed free-standing graphene ribbon as large as 20 micron wide and more than 1 mm long. We partially etch the underneath substrate (Silicon dioxide) along the length (1 mm) of the graphene ribbon. It detaches from the substrate due to charging effect while imaging under electron beam. However, the non-etched part of the graphene ribbon stays intact to the substrate due to Van der Waals forces. Interestingly, we have observed 1 mm long monolayer graphene ribbon which was vertically oriented due to charging effect overcoming the weak Van der Waals force.
Authors : Takuya Tsuda, Andreas Fery
Affiliations : Leibniz-Institut für Polymerforschung Dresden e. V., Hohe Str. 6. 01069 Dresden, Germany Technische Universität Dresden, 01062 Dresden, Germany
Resume : One dimensional nanotubes and nanowires have attracted much attention as next-generation components of organic electronics devices for their unique properties: controlled morphology and dimensions, flexibility and large surface to volume ratio. Recently semiconducting polymer nanotubes and their application to electronic devices such as organic field-effect transistors (OFETs) have been developed. However, there is intrinsic performance limitation of pure polymer nanotubes. In this study, in order to overcome this limitation, we developed novel composite nanotubes and investigated their optoelectronic characteristics. The nanotubes are fabricated with commercial anodic aluminium oxide (AAO) templates by simple sequential spin coating method. The diameter of nanotubes (200 nm and 60 nm) is defined by pore size of the AAO and the length (10 um) is controlled by solution deposition conditions. Composite nanotubes are made of semiconducting P3HT polymer and 35 nm ZnO nanoparticles that improve the photosensitivity. SEM and TEM confirm the homogeneous distribution of the ZnO nanoparticles in the polymer nanotubes. The randomly deposited composite nanotubes on gold electrodes show more than 10 times higher photosensitivity than nanotubes made of pure polymer. These nanotubes are promising novel functional building blocks for advanced flexible or stretchable photo-sensing devices.
Authors : Karolina Piętak (1,2), Ewelina Rozbiegała (1,3), Sebastian Złotnik (1), Paweł Michałowski (1), Mariusz Rudziński (1)
Affiliations : 1. Łukasiewicz Research Network - Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw 2. Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw 3. Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw
Resume : III-nitride materials, GaN-based, with a direct band gap are widely used in optoelectronic and high-power devices such as light emitters, transistors, etc . One of the methods for obtaining III-N epilayers is Metalorganic Chemical Vapor Deposition (MOCVD), which, despite its many advantages, such as good quality and thickness control, also has its disadvantages. The main problem is the presence of remaining carbon, oxygen and hydrogen. Moreover, AlGaN compounds are known to possess increased content of oxygen due to high chemical affinity of Al for oxygen. The oxygen impurity plays a significant role in n-type Si-doped AlGaN, enhancing the effect of the intentional Si doping. However, it has to be noted here that once incorporated into the crystal lattice, the substitutional oxygen acts as a shallow donor in GaN. In our previous work we proved that oxygen improve the diffusion rate of Mg dopant in p-type AlGaN structure . Moreover, O is crucial in defects formation and consequently for electrical characteristics of GaN . In this work, a dependence between the amount and type of impurities present in the obtained undoped and p-type doped AlGaN epilayers, namely carbon and oxygen, and important electrical parameters, i.e. the conductivity for a specific type, mobility, resistance, is investigated. Here, a comprehensive characterization of structural, chemical and electrical parameters is performed by Raman Spectroscopy, X-ray diffraction (XRD) and Hall effect measurements. Additionally, Secondary Ion Mass Spectroscopy (SIMS) is used to determine the amount of impurities in the as-grown heterostructures.  Oka, T., Jpn. J. Appl. Phys, 58 (2019) SB0805.  Michałowski, P. P. et al., Phys. Chem. Chem. Phys., 20 (2018) 13890.  Zlotnik, S. et al., Cryst. Growth Des., submitted (2019). Acknowledgment This work was supported by National Science Centre (NCN) within the project OPUS10 2015/19/B/ST7/02163.
Authors : Harim Oh, Minseok Seo, Jaeyong Kim, Junho Lee, Myeongkyu Lee
Affiliations : Yonsei university
Resume : This article studies the effects of film and substrate on the laser-induced dewetting of metal thin films. Ag and Au films, both 10 nm in thickness, were deposited onto glass and Si substrates and dewetted using a single pulse from a nanosecond-pulsed Nd:YAG laser at lamda = 1,064 nm. The Ag film was completely dewetted into nanoparticles at a pulse energy density of about 70 mJ/cm2 on the glass substrate while an energy density over 390 mJ/cm2 was needed for the Si substrate. This is attributed to the fact that Si has a much higher thermal conductivity than glass and that the laser energy absorbed by the film significantly dissipated into the Si substrate rather than being solely used to heat the film. The Au film required slightly more laser energy in comparison to the Ag film. The energy densities of a laser pulse required to dewet the Ag and Au films were theoretically derived using one-dimensional heat conduction equations and thermodynamic data.The difference between the experimental and calculated pulse energies was more significant for the Si substrate. This indicates that lateral thermal diffusion occurred considerably on the Si substrate even with a nanosecond pulse duration. We demonstrate both experimentally and theoretically that as the thermal conductivity of the substrate increases, the film area dewettable by a laser pulse is decreased.
Authors : Harim Oh, Minseok Seo, Jaeyong Kim, Junho Lee, Myeongkyu Lee
Affiliations : Yonsei university
Resume : Plasmonic color laser printing has several advantages over pigment-based technology, including the absence of ink and toner and the production of nonfading colors. However, the current printing method requires a template that should be prepared via nanofabrication processes, making it impractical for large-area color images. In this study, we show that laser-induced dewetting of metal thin films by a nanosecond pulsed laser can be effectively utilized for plasmonic color printing. Ag, Au, and their complex films deposited on a glass substrate were dewetted into different surface structures such as droplets, rods, and ripples, depending on the incident laser energy. The resulting morphological evolutions could be explained by Rayleigh and capillary instabilities. For a bimetallic film comprising Ag nanowires coated on an Au layer, a few different plasmonic colors were generated from a single sample simply by changing the laser fluence. This provides a possible method for implementing plasmonic color laser printing without using a pre-patterned template.
Authors : Yesul Jeong, Michael C Petty, Jang-Hee Yoon
Affiliations : Korea Basic Science Institute (KBSI), Busan 46742, Republic of Korea Department of Engineering and Centre for Molecular and Nanoscale Electronics, Durham University, South Road, Durham DH1 3LE, United Kingdom
Resume : The thin film, especially those fabricated by solution processing, with a thickness of < 20 nm, are too thin to allow the formation of a continuous conductive path through the bulk of the film. Two dominant factors probably determine the conductivity of these films: surface and bulk defects. Many studies argue that exposure to ambient air causes the degradation of electrical properties, resulting from reactions with surface defects. Since most studies of the conductivity mechanisms are focused on vacuum-processed films, an investigation into the effects of exposure of solution-processed films to different environments is required. In this study, the electrical conductivity of solution processed ZnO films under different measurement conditions has been studied. A dry oxygen environment leads to degradation of the conductivity, possibly due to the absorption of negatively charged oxygen molecules. In contrast, the conductivity was enhanced in an air environment. These results may be related to unreacted hydroxyl groups remaining in the solution-processed films due to the low processing temperature. The hydroxyl groups could be removed by hydrogen plasma treatment; the hydrogen radicals in the plasma react with the hydroxyl groups, followed by vaporisation in the form of water, leaving oxygen vacancies.
Authors : Grzegorz Matyszczak, Sławomir Podsiadło, Emilia Polesiak, Małgorzata Sobieska
Affiliations : Warsaw University of Technology, Faculty of Chemistry
Resume : A large interest in semiconductors is observed due to their applications in electronics and renewable energy harvesting. 2D layered chalcogenides, such as tin(IV) sulphide, have attracted great research interests due to their potential usage in nanoelectronics and nanophotonics. This study presents ultrasound assisted synthesis of SnS2 micro- and nanopowders from solutions of tin(II) and tin(IV) chlorides and thioacetamide in ethanol. Composition of the obtained materials have been determined with powder X-ray diffraction and energy-dispersive X-ray spectroscopy. Size of particles have been determined from scanning electron microscopy images and using the Scherrer equation. Band gaps of the obtained materials have been estimated with Tauc method.
Authors : L. Borkovska1, N. Korsunska1, A. Rachkov2, T. Kryshtab3
Affiliations : 1V. Lashkaryov Institute of Semiconductor Physics of the NAS of Ukraine, Kyiv, Ukraine 2Institute of Molecular Biology and Genetics of the NAS of Ukraine, Kyiv, Ukraine 3Instituto Politécnico Nacional – ESFM, Av. IPN, Ed.9 U.P.A.L.M., 07738, Ciudad de Mexico, Mexico
Resume : The Cu-In-S nanocrystals (NCs) are characterized by direct band gap, high absorption coefficient and intense defect-related photoluminescence (PL) in the visible spectral range. The NCs also show low toxicity and attract increased attention for applications in solar energy conversion, photodetectors, light emitting devices and bio-labeling. In this work, the PL properties of CuxIn4S7 NCs (x=0.3-4.0) synthesized in aqueous media and embedded in gelatin film have been examined. The PL spectra of the NCs demonstrate PL band in the yellow-red spectral range with maximum shifted from 645 to 700 nm as the x increased from 0.3 to 1.2. The PL excitation spectra show a clear shoulder at 550-600 nm, ascribed to optical transitions via defect states. The PL peak position changes on up to 80 meV as the excitation energy varies within this shoulder. The PL excitation spectra are found to be similar to optical absorption spectra. The increase of x from 1.2 to 4.0 does not change PL peak position but results in the decrease of integrated PL intensity indicating that Cu-rich NCs are low-emissive. In turn, the PL spectra of Cu-deficient NCs (x=0.3-0.5) demonstrate an additional band in the range of 500-600 nm that overlapped spectrally with the shoulder in the PL excitation spectra. The core-shell CuInS/CdS and CuInS/ZnS NCs demonstrate larger PL intensity as compared with the bare ones; the PL peak being shifted to the red in CdS coated NCs and to the blue in ZnS coated ones. The largest PL intensity is found for the NCs with x=0.5-1.0. The composites do not change their optical properties under visible light irradiation confirming that they are quite suitable for optical applications.
Authors : Kyung Seok Woo, Yongmin Wang, Jihun Kim, Yumin Kim, Young Jae Kwon, Jung Ho Yoon, Woohyun Kim, and Cheol Seong Hwang
Affiliations : Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University
Resume : A true random number generator (TRNG) based on the stochastic delay and relaxation times of the threshold switching (TS) behavior in a Pt/HfO2/TiN (PHT) memristor is proposed. This device not only has a stochastic delay time before it reaches the ON state when it is being switched on but also has a stochastic relaxation time in the process of switching back to the OFF state. The stochasticities of this device are attributed to its electron trapping and detrapping processes. This electronic-switching-based memristor exhibits several advantages, such as low power consumption and high reliability. A new circuit is designed to improve the simplicity, miniaturization, and lifetime of TRNG. The bitstreams collected from this TRNG pass the National Institute of Standards and Technology randomness tests without post-processing, verifying the feasibility of adopting the memristor in hardware security applications. The bit generation rate in this work is sufficient for encryption applications requiring low power and low speed.
Authors : V.A. Gamaliy, V.V. Butskii, S. Piskunov, I.Isakovica, A.I. Popov, N.V. Krainyukova
Affiliations : B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Kharkiv, Ukraine; Institute of Solid State Physics, University of Latvia, Riga, Latvia
Resume : Nowadays SrTiO3 thin films are used in tunable high temperature superconductor microwave filters, as substrates for epitaxial growth of high temperature superconductors, in catalysis, and so on. Therefore, understanding and control of perovskite surface properties is very important for many (nano)electronic applications. The SrTiO3 low index surfaces impose their own symmetry, which strongly affects the orientations of the oxygen octahedra in the first outermost surface layers. It results in the change of rotation angles and thus in surface reconstruction, leading to the surface properties different from that of the bulk. In our study we have applied the RHEED method to study the SrTiO3 (001) surface structure. We report an increase of the surface lattice parameters along with decrease of the temperature from 300 K down to 6 K. Moreover, the lattice constants of the 2D unit cell increase with respect to their bulk values moving closer to the surface in a stepwise way from layer to layer. We describe such a change of surface morphology as a result of rotations of metal-centered oxygen octahedra around the axes normal to the (001) surface, that is presumably due to the specific character of the low-temperature phase transitions imposed by the surface symmetry. The experimental observation is supported by our ab initio calculations performed on modified SrTiO3 (001) surface. Influence of atomic reconstruction on the surface electronic properties is thoroughly discussed.
Authors : Abhishek Anand and Mukesh Chander Bhatnagar
Affiliations : Department of Physics, Indian Institute of Technology, New Delhi – 110016
Resume : Flexible polymer based piezoelectric nanogenerator have much more attention due to mechanical flexibility, lower fabrication cost and energy harvesting from sources such as vibration, mechanical load, human motion and waste heat. Here, we report a flexible piezoelectric nanogenerator with different kinds of nanofiller such as reduced graphene oxide and bismuth aluminate Bi2Al4O9 ceramic in Poly(vinylidene fluoride) (PVDF) matrix. The structural and morphology properties of nanocomposite films are examined by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). In this work, the fraction of beta- phase enhance from 53 to 76 % with incorporation of these nanofillers has been analyzed by Fourier transform infrared spectroscopy (FTIR). The nanocomposite film of PVDF/Bi2Al4O9/RGO showed maximum value of remnant polarization (Pr) is 0.01897 microC/cm2 at an electric field of 165 kV/cm. The value of electric output voltage and current generated from nanocomposite films is to be maximum 5.92 V and 0.76 microA for PVDF/Bi2Al4O9/RGO based nanocomposite. The PVDF/Bi2Al4O9/RGO based nanocomposite generated a maximum output power density of 0.457 microW/cm2 at 12 MOhms resistance which is around 20 times more than that of bare PVDF film.
Authors : M.N. Shamis1, P.V. Makushko1, T.I. Verbytska1, S.I. Sidorenko1, G. Beddies2, N.Y. Safonova2, M. Albrecht2, and Yu. N. Makogon1
Affiliations : 1 Igor Sikorsky Kyiv Polytechnic Institute, Department of Physics of Metals, Peremogy av. 37, 03056, Kyiv, Ukraine 2 University of Augsburg, Institute of Physics, Universitätsstraße 1, D-86159, Augsburg, Germany *E-mail: email@example.com
Resume : FePd thin films are of interest as a material for data storage of ultra high density. Annealing atmosphere considerably influences the L10 structure formation and magnetic properties of FePd thin films. The aim of this study was to investigate the phase composition, structure and magnetic properties of FePd thin films with Au underlayer after annealing in vacuum and hydrogen atmosphere in the temperature range of 600 oC-700 oC. FePd/Au films were deposited on SiO2/Si(001) substrates at room temperature by magnetron sputtering. As-deposited and annealed films were analyzed by XRD, AFM, and SQUID-VSM. It was observed that the L10 phase in FePd(4.7 nm)/Au(0.3 nm) bilayers was formed after annealing for 20 h in vacuum at 600 oC and 650 oC, respectively. These films reveal hard magnetic properties with coercive fields of 1.1 kOe and 1.33 kOe when applying in-plane magnetic fields, correspondingly. Annealing in hydrogen leads to a strong modification of the film structure, accelerates the L10 ordering process and considerably improves the magnetic properties in comparison with annealing in vacuum. In a film with Au(0.3 nm) underlayer, the ordered L10 phase is formed at 650 oC( annealed for 1 h) and the film reveals perpendicular magnetic anisotropy. The increase in Au underlayer thickness to 0.9 nm or rise in annealing temperature to 700 oC results in chemical disordering and decrease in saturation magnetization, becoming even non-magnetic. However, a rather smooth film morphology is obtained for films annealed in hydrogen compared to annealing in vacuum, which is an important factor for practical use of this material.
Authors : Jae-Ho Jang, Hee Jung Park, Jeong Yong Park, and Do-Hoon Hwang*
Affiliations : Pusan National University
Resume : Red phosphorescent iridium(III) complexes, (TPIQ)2Ir(acac) and (TPIQ)2Ir(ppy), based on 1-(4-(trimethylsilyl)phenyl)isoquinoline (TPIQ) as the cyclometalated main ligand and either acetylacetone (acac) or 2-phenylpyridine (ppy) as an ancillary ligands, were synthesized for solution-processed organic light-emitting diodes (OLEDs). The Ir(III) complex, (PIQ)2Ir(acac), which consists of 1-phenylisoquinoline (PIQ) as the main ligand and acac as the ancillary ligand, was also synthesized as a reference. The photophysical, electrochemical, and electroluminescent (EL) properties of Iridium(III) complexes were investigated. Red OLED using (TPIQ)2Ir(ppy) as an emitter exhibited significantly more improved a full-width at half-maximum (FWHM) by introduction of ppy as an ancillary ligands. The EL spectrum of (TPIQ)2Ir(ppy) exhibited emission maximum at 640 nm with a full-width at half-maximum (FWHM) of 113 nm and Commission Internationale de L’Eclairage (CIE) coordinates of (0.68, 0.32) at 1000 cd/m2. The device with 7 wt% doping concentration of (TPIQ)2Ir(ppy) exhibited maximum luminance of 6,296 cd/m2, maximum luminous efficiency of 15.93 cd/A, power efficiency of 5.26 lm/W, and external quantum efficiency of 5.45 %, respectively.
Authors : Violeta Dediu, Ileana Cernica, Octavian Ionescu, Silviu Vulpe Oana Tutunaru, Cosmin Romanitan
Affiliations : National Institute for Research and Development in Microtehnologies, Bucharest, Romania
Resume : Different nanostructures based on ZnO and SiO2 combination prepared through chemical and physical methods, were investigated for ammonia surface acoustic wave microsensors. ZnO nanorods (NR) with diameters under 50 nm were obtained through solvothermal method and then decorated with gold nanoparticles through chemical reduction. Combinations consisting of ZnO (NR) and SiO2 (obtained by RF sputtering and chemical methods) were deposited on langasite or quartz SAW structures and used as sensitive layer materials. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) were used to investigate the morphology and structure of the obtained nanostuctures. The sensing behaviour of nanostructures towards ammonia was investigated. The gas response of these complex nanostructures was superior compared with those of single ZnO layer reported in the literature. The tested materials have proven good sensitivity and stability, reversibility at room temperature. Also, the mechanism of ammonia sensing is discussed.
Authors : Maria Vasilopoulou, Dimitris Davazoglou
Affiliations : Institute of Nanoscience and Nanotechnology, National Center for Scientific Research, Athens, Greece
Resume : Metal oxides possess a high potential as new high-performance charge transport materials in organic optoelectronic devices due to their appropriate electronic configuration (valence and conduction band positions). However, low conductivity, related to high iconicity in metal–oxide bonds, acts as major roadblocks for using metaloxide as highly efficient charhe transport materials. Here, we first disclose a novel strategy to design metal oxide materials of high conductivity for use as electron transport materials. The incorporation of F leads to substantial increase of the n-type conductivity, which is beneficial for boosting electron transport capability.
Authors : Chihun Sung1,2, Jisu Han1,2, Juhee Song1, Chil Seong Ah1, Seong M. Cho1, Joo Yeon Kim1, Chi-sun Hwang1, Jeong-IK Lee1 and Tae-Youb Kim1,2*
Affiliations : 1Reality Device Research Division, ICT Materials & Components Research Laboratory, Electronicsand Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea, Tel.:82-42-860-5267, E-mail: firstname.lastname@example.org ; 2Next generation display Lab., ICT(Advanced Device Technology), University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
Resume : Reflective displays present information that use external light such as sunlight and internal light. Therefore, outdoor visibility is good and the light can be reflected through the reflector at the back of the screen. In addition, no backlight is needed that leads to reduce the power consumption and light reflection. Owing to these characteristics, various reflective displays have been researched such as reversible electrodeposition(RED) devices, electrowetting display and electrophoretic display. Especially, RED devices which effectively control the reflectance and transmittance of external light and minimize the absorption of light are most attended candidate for reflective displays. RED devices are consisted of two transparent electrodes and electrolyte. It is activated with the deposition or dissolution of metal such as Ag, Cu, and Bi onto one of the electrodes that shows reflection or transparent states. However, in order to apply it to a display, color implementation can be considered as a important factor. To induce the color in display device, ITO thin film interference has been studied. YANBIAO LYU et al. demonstrated multi-color modulation of solid-state display by adjusting of properties for instance thickness, refractive index and absorption coefficient depending on ITO thickness and annealing temperature. The multiple colors are appeared on the Pt coated silicon substrate by thin film interference effect. However, there is no color RED device which has ITO thin film interference. In this study, a color-switchable RED device was fabricated by using ITO interference effect. Different thickness of ITO thin films was involved to realize red, green and blue colored mirror. Device is shown RGB colored mirror, transparent and Ag mirror state by applying voltages.
Authors : Honggi Min, Boseok Kang, BongSoo Kim, Jeong Ho Cho*
Affiliations : Yonsei university; Sungkyunkwan University; UNIST;
Resume : Fluorinated polyimides gate dielectric based on 6FDA-BisAAF-PI and 6FDA-TFDB-PI were synthesized to use as a gate dielectric to fabricate high performance organic field-effect transistors (OFETs). The fluorine substituted into polyimide chain was improved the efficiency of solution-process to make uniform film. These fluorinated polyimide make it possible to fabricate transparent devices. Especially, OFETs based on 6FDA-TFDB-PI which has low surface energy have high-performance because defect density formed by grain boundary is lowest. The OFETs based on 6FDA-TFDB-PI gate dielectric have high carrier mobility (1.83 cm2V-1s-1 for the p-type pentacene FETs and 0.56 cm2V-1s-1 for the n-type PTCDI-C8 FETs) and a high on/off ratio exceeding 106. And, we check that the devices have excellent electrical stability from measured bias stress experiment. The 6FDA-TFDB-PI film was used to fabricate complementary inverters that have high gain value. Lastly, the logic gate circuit (NAND, NOR) were successfully fabricated using 6FDA-TFDB-PI gate dielectric.
Authors : N. Enea1, N.D. Scarisoreanu1, V. Ion1, F. Andrei1, D. Manica1, M. Dinescu1, A. Moldovan1 and I. Boerasu1
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, RO-077125, Magurele, Romania;
Resume : Lead-free ceramic materials such as (Ba1−xCax)(ZryTi1−y)O3 have high piezoelectric coefficient, high dielectric constant, good electromechanical coupling coefficient and are useful in applications such as piezo transducers and sensors. At the same time, due to their nature they are rigid materials and cannot be used in applications involving flexible devices. On the other hand, polymeric piezoelectric materials such as Polyvinylidene Fluoride have low piezoactivity and low dielectric constant but are flexible and find their applicability in areas such as flexible electronics. Combining ceramic and polymeric materials, piezoelectric composites with high coupling coefficients, average dielectric constant, medium cost and can be used in applications requiring flexibility, such as pressure sensors or bio-compatible devices. Thin film of PVDF/BCZT were deposited on Pt-kapton substrate by Matrix Assisted Pulsed Laser Evaporation technique. Thin films of BCZT have been deposited by PLD for comparison purposes. Piezoforce microscopy measurements on PVDF/BCZT/Pt/Kapton films revealed high values of the d33 coefficient and good switching behavior, as shown by phase variation under electric field. The out-of-plane PFM response shows strong domain contrast, indicating that the material is polar with a polarization vector oriented mainly along the c-axis. The good piezoelectric properties of the PVDF/BCZT films indicate the possibility to employ these structures as piezoactive elements.
Authors : Won Seok CHOI, Jeong Eun PARK, Jae Joon JANG, Donggun LIM.
Affiliations : Korea National University of Transportation.
Resume : Divided cell of c-Si solar cells using laser can get more high voltage and efficiency than 6 inch cells. In this paper, we fabricated divided cells using nanosecond green laser and analyzed structural characteristics. The experiment conditions were fixed in laser power 90% (9 W) and the number of laser scribing 5 numbers. And, the conditions were changed with a laser frequency of 100 to 700 ㎑ and a laser speed of 50 to 200 ㎜/s. As a result of the laser frequency experiments, it was not possible to fabricate divided cells under 300 ㎑ or less frequency conditions. Sufficient processing depth of about 60 ㎛ was formed under the conditions of 500 to 700 ㎑ and a divided cell was fabricated. However, Heat Affected Zone(HAZ) of about 80 ㎛ width was occurred in conditions of 700 ㎑ or more of the frequency due to excessive lasers processing. Therefore, in order to minimize the HAZ, the frequency of the laser was fixed at 500 ㎑. In conditions of laser speed of 150 to 200 ㎜/s, it was not proceeded to obtain a sufficient cell depth due to the fast laser processing. On the other hand, a sufficient processing depth of about 60 ㎛ was formed under the conditions of 50 to 100 ㎜/s and a divided cell was fabricated. However, HAZ width of about 90 ㎛ was generated by the excessive laser processing under the conditions of 50 ㎜/s or less of the speed. As a result, we confirmed a suitable process condition to obtain divided cells in the laser frequency of 500 ㎑, laser speed of 100 ㎜/s.
Authors : Eun Ji Bae, Jeong Eun Park, So Mang Park, Seon Wol Jeon, Donggun Lim
Affiliations : Korea National University of Transportation
Resume : Currently, solar cells have low output due to the space between modules. On the other hand, ECA bonding cell can arrange more cells and expecting higher output. In this study, CIGS thin film solar cell using a stainless steel substrate was bonded with ECA materials and the cell characteristics were analyzed. ECA materials for the bonding cell were used and it was called as ECA 1, ECA 2 and ECA 3. Experimental conditions were changed to curing time of 30 ~ 180 sec and curing temperature of 120 ~ 210 ℃ with ECA material. As a result of the curing time experiment, the efficiency difference from single cell of ECA 1 was -0.5% at 150 sec, ECA 2 was +0.7% at 150 sec, and ECA 3 was +1.5% at 60 sec. As a result of the curing temperature experiment, the efficiency difference from single cell of ECA 1 was 0% at 180 ℃, ECA 2 was +0.8% at 120 ℃, and ECA 3 was +1.5% at 150 ℃. It is confirmed that as the curing temperature increases, the lubricating oil was smoothly decomposed and had high conductivity. As a result, ECA 3 material showed the best efficiency change at curing time of 60 sec and curing temperature of 150 ℃. It was confirmed that the electrical characteristics of the ECA bonding cell were improved by the increase of the F.F was 13.9% and parallel resistance was 32.38 Ω than single cell.
Authors : Daniel J. Jastrzebski (1), Anna Rydzkowska (2), Oskar Sadowski (2), Pawel Pęczkowski (3), Cezariusz Jastrzębski (2)
Affiliations : (1) Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland (2) Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland (3) 1 Cardinal Stefan Wyszyński University, Faculty of Mathematics and Natural Sciences. School of Exact Sciences, Department of Physics, K. Wóycickiego 1/3 Street, 01-938 Warsaw, Poland
Resume : Gallium sulphide (GaS) belongs to the group of materials with a layer structure. It has an oblique energy gap of value 2.55 eV. An optical energy gap is greater by approx. 0.45 eV . In the GaS case, we do not observe the effect of straightening the gap as the thickness of the sample decreases. GaS monolayers are connected relatively weak van der Waals forces, which allows to obtain thin GaS samples as a result of micromechanical exfoliation. The perspective applications of GaS result from its very high absorption coefficient in the range of blue and near UV light and efficient electroluminescence in the blue-green range. Good mechanical and thermal properties make GaS appropriate for nano-devices, manufactured on flexible substrates. GaS has a high resistance to doping by different atoms . In this work the influence of magnetic ion on Raman scattering in these materials was studied. The magnetic atoms (Fe, Mn, Ni, Co) has been added in the GaS CVT crystal growth process. The doped GaS samples were pre-characterized using XRD, SEM and EDX methods. The Raman studies were conducted for different excitation wavelengths of the laser and in the temperature range from 80 to 300 K. The influence of doping with magnetic atoms on Raman scattering processes were analyzed. 1. C. H. Ho and S. L. Lin, Optical properties of the interband transitions of layered gallium sulfide, J.Appl. Phys. 100, 083508 2006, http://dx.doi.org/10.1063/1.2358192. 2. Hui Chen, Yan Li, Le Huang, and Jingbo Li, Influential Electronic and Magnetic Properties of the Gallium Sulfide Monolayer by Substitutional Doping, J. Phys. Chem. C, 2015, 119 (52), pp 29148–29156, DOI: 10.1021/acs.jpcc.5b09635T.
Authors : Tuan Anh Vuong, Soohyuk Yang, Jongsun Kim, Hyungtak Kim
Affiliations : Hongik University
Resume : As hydrogen is a very promising source of energy for automotive or fuel cell applications, there has been the demanding need of hydrogen sensors that can operate at high temperature over 300 oC at which hydrogen can become a serious threat. Normally-on GaN HEMT shows more stable characteristics with lower output conductance with zero-gate bias as compared to a floating gate. We have fabricated 2-terminal HEMT-type gas sensors with source-gate connected on AlGaN/GaN-on Si substrate and characterized hydrogen sensing performance with 4 %-hydrogen in Ar. The hydrogen sensitivity of the S-G connected sensors was increased from 13 to 20 % at 200 oC as compared to the floating-gate sensors. The AlGaN barrier layer below the Pt-gate area was partially etched by the dry-etching process to enhance the sensitivity further. The S-G connected sensor with 9 nm-AlGaN barrier demonstrated the hydrogen sensitivity of 85 %. The sensing performance was still demonstrated with the sensitivity of 35 % at 500 oC.
Authors : Doludenko I.2,1, Zagorskiy D.1, Frolov K.1, Perunov I.1, Kanevski V.1, Muslimov A.1, Panov D. 2,1
Affiliations : 1 Center of Crystallography and Photonics of RAS, Moscow, Russia 2 National Research University Higher School of Economics, Moscow, Russia
Resume : Using the method of matrix synthesis, it is possible to obtain arrays of nanowires (NWs) from alloys of magnetic metals. Similar structures can be applied in different areas of microelectronics. In this work, NWs samples consisting of FeNi and FeCo alloys with different amounts of Fe were obtained. The deposition was carried out in a pre-prepared matrix based on track membranes (Pore diameter – 100 nm, pore length – 12 μm , pores density – 8,9*10**8 cm**-2). After electrodeposition, the samples were examined using X-ray structural analysis. The results showed the presence of two phases (FeNi / FeCo and Ni / Co) in samples with low Fe concentration. Samples were studied using SEM with elemental analysis. Elemental analysis showed that the concentration of Fe atoms in FeNi NWs is higher than thesame in the electrolyte. This effect is different: for samples with the lowest concentration of Fe it si approx. 10%; for samples with the highest concentration of Fe -35%. For the case of FeCo, differences in concentrations are observed only in the case of a high Fe content. It increases with increasing concentration of Fe in the electrolyte, the maximum is 11%. The Mossbauer spectra for these samples were investigated: obtained data (dependence of magnetization of pores diameter and NWs composition) are presented and discussed. Acknowledgements. Synthesis of NWs was supported by RFBR grant No.18-32-01066, SEM measurements- by the State Task of FNIC “Crystallography and Photonics” of RAS.
Authors : Cherkasov D.1, Doludenko I.1, Khaibulin R.2, Bedin S.1, Zagorskiy D.1
Affiliations : 1 Center of Crystallography and Photonics of RAS, Moscow, Russia 2 Kazan Institute of Physics and Technology. E. K. Zavoisky Kazan Scientific Center of RAS, Kazan, Russia
Resume : One of the most important parameters of metallic nanowires (NW) are their magnetic properties. The possibility to change the deposition process and the properties of obtained NWs by applying the external field was investigated. Electrodeposition of iron-group metals into the pores of the track etched membrane (TM), was carried out in the electrochemical cell. The magnetic field was varied from 0 to 0.3 T by applying external magnet. Single and multi-component samples – cobalt and FeNi alloy NWs, as well as Cu/Ni layered NWs were deposited. During pore filling, the time dependence of the current was recorded. The pore filling time was determined by a sharp increase in the current associated with the exit of the growth zone to the surface of the TM. It was shown that the pore filling time in the presence of a magnetic field is lower by 10%. Since the experiment uses a permanent magnet with dimensions comparable or smaller than the galvanic cell. This effect can be associated with a panderomotive force- it could be explained by inhomogeneous magnetic field. Samples were examined using a scanning electron microscope. It was shown that magnetic field slightly affects on the topography of homogeneous NWs, while effect on heterostructural NWs was much higher – the formation of the cavities was detected. The X-ray research showed a change in the relative intensities of reflexes in the application of MF, which could be explained by the appearance of texture. Magnetometry was also performed, which showed a weak dependence of magnetic properties on the applied magnetic field. The nature of this effect is discussed.
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Nanomaterials and Memory Devices : Jean-Claude Grivel, Yogendra Mishra
Authors : N. A. Pertsev
Affiliations : Ioffe Institute, St. Petersburg, Russia
Resume : This invited talk presents an overview of the most important experimental and theoretical results on electrically induced spin dynamics in ferromagnetic nanostructures mechanically coupled to ferroelectric substrates. In such multiferroic hybrids, the substrate serves as a piezoelectric transducer converting an electrical input signal into a mechanical stimulus acting on the ferromagnetic overlayer. Under appropriate piezoelectric deformations, the overlayer magnetization loses stability against precessional motion owing to the magnetoelastic coupling between spins and substrate-induced strains. Depending on the input signal and the device design, a strain pulse, bulk elastic wave, or surface acoustic wave is created in the ferromagnetic heterostructure. As a result, the electrically excited magnetic dynamics can have the form of a steady precession, spin reorientation transition, magnetization switching, or a spin wave. This remarkable feature makes ferromagnetic-ferroelectric hybrids promising for the development of advanced spintronic devices with ultralow power consumption. In particular, hybrids comprising magnetic tunnel junctions can be employed as electric-write magnetoresistive nonvolatile memory cells. Furthermore, efficient spin injectors based on dynamically strained ferromagnet/normal metal bilayers could be developed. Other discussed applications include logic elements utilizing elastically generated spin waves and electrostatically tunable microwave devices.
Authors : Hasan Abbas Jaffery1 Jung Jongwan1* Sajjad Hussain1*
Affiliations : 1Graphene Research Institute, Sejong University, Seoul 143-747, Republic of Korea: Department of Nanotechnology & Advanced Materials Engineering and Graphene Research Institute, Sejong University, Seoul 143-747, Republic of Korea
Resume : Metal–oxide semiconductors are widely used to fabricate metal–oxide–semiconductor field effect transistors  (FETs), solar cells, and photodiodes . IGZO has drawn more attention from researchers due to its high field-effect mobility, low threshold voltage, transparent and low-temperature deposition.  In spite of this, IGZO has been known that the optical bandgap is Eg = 3.2 eV, which indicates that it could not be activated on the condition of UV wave length greater than 400 nm . This problem can be reduced by coupling n-IGZO with p-type material. In this research, p-GeSe/n-IGZO van der Waals heterojunctions were fabricated on a SiO2/Si substrate to study the electrical and electronic properties. GeSe has an indirect bandgap of 1.08 eV in bulk and a direct bandgap of ~1.7 eV in monolayers [5,6]. It has been reported that GeSe has a high photo responsivity along the a3 (perpendicular to the plane) direction.  The IGZO (In–Ga–Zn = 1:1:1) layer of 30 nm thickness was deposited on SiO2/Si with 50W power for 1200 Seconds with 3% oxygen at 0.5 Pa in ambient argon. The film was deposited by means of RF Magnetron sputtering. The deposited IGZO was then annealed at 400°C for 1 h to improve the crystal structure and stability of the IGZO. After annealing, few layers of GeSe was exfoliated and transferred on IGZO Hall bar to make a hetro-junction. Au/Ti (50 nm/5 nm) contacts were deposited over GeSe by Ebeam Lithography. References 1) Kurokawa, Y et al. Applications of Crystalline Indium-Gallium-Zinc-Oxide Technology to LSI: Memory, processor, image sensor, and field programmable gate array, Fifth Asia Symposium on Quality Electronic Design (ASQED 2013), 2013, 26-28, pp 66-71. 2) Jariwala, D. et al. Gate-tunable carbon nanotube–MoS heterojunction p-n diode. Proceedings of the National Academy of Sciences, 2013, 110 (45), 18076-18080. 3) Zhang, J. et al., A. Flexible indium–gallium–zinc–oxide Schottky diode Operating Beyond 2.45 GHz. Nature Communications, 2015, 6, 7561. 4) Chen, W. T. et al. High-performance light-erasable memory and real-time ultraviolet detector based on unannealed indium-gallium-zinc-oxide thin-film transistor. IEEE. Elec. Dev. Lett. 2012, 33, 77–79 (2012). 5) Makinistian, L. et al. A. J Phys-Condens Mat 2007, 19, (18). 6) Gomes, L. C. et al.Phys Rev B, 2016, 94, (15). 7) Mukherjee, B. et al. Acs Appl Mater Inter 2013, 5, (19), 9594-9604
Authors : Hussain Muhammad1 Jung Jongwan1* Sajjad Hussain1 *
Affiliations : 1Graphene Research Institute, Sejong University, Seoul 143-747, Republic of Korea: Department of Nanotechnology & Advanced Materials Engineering and Graphene Research Institute, Sejong University, Seoul 143-747, Republic of Korea
Resume : Metal-2 dimension semiconductor Schottky-barrier diodes with forward and reverse I‐V characteristics have been fabricated using asymmetric metal contacts. In this research work, a p-type Germanium selenide (p-GeSe) was fabricated. p-GeSe belongs to the family of IV-VI layered chalcogenide semiconductors with orthorhombic structure (Pnma)  and band gap, 1.07 eV . A single unit cell contains eight atoms situated in two adjacent double layers along the z-axis. The atoms in each double layer are bonded to their three nearest neighbors in a zig-zag fashion. The neighboring Ge atoms surrounding the Se atoms. The van der Waals force between the adjacent layers makes the crystal cleavable along its x-y plane . Single crystalline flakes of p-GeSe were mechanically exfoliated by using 3M scotch tab  and the Deterministic dry transfer method was used to transfer the good quality of few layers flakes onto the Si/SiO2 . Electrodes were designed in desired geometry over p-GeSe flakes by Electron Beam Lithography. The Schottky-barrier has been made due to the asymmetry of ultra-low Palladium/Gold (Pd/Au) and high resistive Chromium/Gold (Cr/Au) metal contacts. The Schottky diode has performed an explicit rectifying behavior with an on/off ratio of ̴103. References  Makinistian L and Albanesi E A 2007 Ab initio calculations of the electronic and optical properties of the germanium selenide J. Phys.: Condens. Matter 19 186211 References  Eymard R and Otto A 1977 Optical and electron-energy-loss spectroscopy of GeS, GeSe, SnS, and SnSe single crystals Phys. Rev. B 16 1616  K. S. Novoselov , D. Jiang , F. Schedin , T. J. Booth , V. V. Khotkevich , S. V. Morozov , A. K. Geim , Proc. Natl. Acad. Sci. USA 2005 , 102 , 10451 .  Yi, M., & Shen, Z. (2015). A review on mechanical exfoliation for the scalable production of graphene. Journal of Materials Chemistry A, 3(22), 11700–11715. doi:10.1039/c5ta00252d  Castellanos-Gomez, A., Buscema, M., Molenaar, R., Singh, V., Janssen, L., van der Zant, H. S. J., & Steele, G. A. (2014). Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping. 2D Materials, 1(1), 011002. doi:10.1088/2053-1583/1/1/011002
Authors : Jisu Han1,2, Chihun Sung1,2 Juhee Song1, Chil Seong Ah1, Joo Yeon Kim1, Seong Mok Cho1, Hojun Ryu1, Chi-Sun Hwang1, Jeong-Ik Lee1 and Tae-Youb Kim1,2*
Affiliations : 1 Reality Device Research Division, ICT Materials & Components Research Laboratory, Electronics and Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea; 2 Next generation display Lab., ICT(Advanced Device Technology), University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
Resume : Active using of display at both indoor and outdoor condition is one of the challenges in display technology. The transflective display which uses backlight at indoor and external light at outdoor is fabricated for this purpose. Nevertheless, the transparent part and mirror part is separated that cannot be control the degree of application of mirror or transparency. Reversible electrodeposited devices have transparent and mirror state which can apply to the transflective devices. It is activated by electrochemical reaction of ions and electrons which make deposition/dissolution of Ag on the working electrode. Hence, it is adjusted the degree of mirror or transparent state. However, bi-stability of deposited Ag thin films is low due to the existence of dissolution agent, 〖Cu〗^ and 〖Br〗^- ions in electrolyte. The 〖Cu〗^ ions help clear dissolution of Ag when bleaching mechanism, however, it is a main reason of erasing process of Ag thin films. Therefore, elimination of 〖Cu〗^ ions from electrolyte can effectively improve the bi-stability of devices. Furthermore, the counter electrode is needed as mediator of electrochemical reaction to prevent reaction of 〖Br〗^- ions which is a self-erasing agent. TiO2 thin films is a candidate for counter electrode which can store and release both electrons and ions when their reduction/oxidation processes. In this study, we fabricated the reversible electrodeposited devices based on the TiO2 mediator which can effectively limit the reaction of self-erasing process. Layered TiO2 thin films were investigated to find suitable charge balance with working electrode. Moreover, the starting redox reaction balance between working and counter electrodes were achieved by pre-deposited Ag thin films.
Authors : Sandeep Munjal and Neeraj Khare
Affiliations : Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016, India
Resume : We report deterministic conversion of write once read many times (WORM) resistive switching (RS) memory to a volatile and non-volatile RS memory in a simple Ag/CoFe2O4/Pt devices via tuning the compliance current (ICC). The ICC = 10-1 A causes a WORM type resistive switching behavior with a large resistance ratio (~106). The WORM type RS behaviors could be attributed to the formation of a thick and stable conducting filament formed of oxygen vacancies and Ag ions. A simultaneous magnetization and resistive switching confirm the multifunctional behavior of the WORM device and suggests the presence of valance change mechanism of resistive switching. With the controlled application of ICC, the reversible volatile and non-volatile resistive switching can be obtained. For the smaller ICC the device exhibit the volatile RS behavior with atomically sized conducting filament showing the quantum conductance. An intermediate ICC causes the non-volatile bipolar RS behavior in the Ag/CoFe2O4/Pt devices, which could be originated from formation and rupture of filament consisting of Ag ions. The device shows a low resistance state (LRS) and a high resistance state (HRS), which are stable with time and reproducible in RS cycles. Endurance characteristics of the present RS device (> 500 switching cycles) show no noticeable degradation, and the ultimate resistance ratio always remains ~ 103, which ensures reproducibility, reversibility and controllability of the RS features of the present device. The HRS of the device shows semiconducting conduction mechanism, whereas the LRS was found Ohmic in nature. The temperature dependent resistance studies revealed that the electrochemical metallization plays an important role during the switching process in volatile and non-volatile modes of resistive switching of present device. The compliance current controlled resistive switching modes with a large memory window make the present device a potential candidate to pave the path for future resistive switching devices.
Authors : V. Diez-Cabanes*, A. Galanti , M. Souto , Q. Wang , I. Ratera , N. Koch , J. Veciana , P. Samorì , J. Cornil 
Affiliations :  Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, B-7000 Mons, Belgium. email@example.com  Université de Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, 67000, Strasbourg, Fance  Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain  Institut fur Physik & IRIS Adlershof Humboldt-Universitat zu Berlin Brook-Taylor-Str. 6, 12489 Berlin, Germany
Resume : Molecular switches have attracted a great attention in the field of Nanotechnology due to their ability to reversibly switch between several states by means of external stimuli (such as light or electrical current), and thus to display several functions and mixing electronic with optical, magnetic or sensing properties. In order to achieve such multi-functionality, we can introduce molecular switches as building blocks in order to form responsive components and interfaces to be integrated into electronic devices to gain a dynamic control of their properties. In our work, several theoretical approaches and characterization methods were employed to characterize various switchable architectures. In a first stage, Molecular Mechanics and Dynamics (MM/MD) simulations were used to evaluate the different forces driving the self-assembled patterns obtained with a multi-state compound formed by three azobenzene groups, which could be employed as building blocks of responsive host-guest systems or organic frameworks. Ultraviolet Photoemission Spectroscopy (UPS) measurements were then confronted to Density Functional Theory (DFT) calculations to shed light on the change in the electrode surface properties upon adsorption of switchable Self-Assembled Monolayers (SAMs) based on diarylethene (DAE) molecules, which can be exploited to dynamically tune the amount of current injected in devices such as organic field-effect transistors (OFETs) and light-emitting diodes (OLEDs). Finally, the transmission through Donor-Acceptor (D-A) dyad based switchable junctions, where the perchlorotriphenylmethyl (PTM) radical acts as electron acceptor (A), was analyzed with the Non-Equilibrium Green Function method coupled to DFT (NEGF-DFT) calculations in order to develop new functional rectifiers.
Authors : Priya Darshni Kaushika, M. Rodner, G. Greczynski, D.K. Avasthi, Jens Erikssona, Mikael Syväjärvi, Rositsa Yakimova. G. Reza Yazdi
Affiliations : Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden
Resume : We have use ion irradiation as a tool to tailor the surface of epitaxial graphene (EG) on SiC for sensing application. EG was irradiated with 30 keV and 100 MeV silver (Ag-) ion at fluences range of 5× 1012 - 5× 1014 ions/cm2 and 6.6× 1011 - 2× 1013 ions/cm2, respectively. Structural modifications were studied through Raman and XPS while morphological modifications were investigated using AFM. Raman spectra shows decrease in 2D with increase in fluence for both low and high energy samples. We also observed an initial increase in the intensity of D peak with increase in fluence up to 1× 1013 ions/cm2 and 5× 1013 ions/cm2 fluence in low and high energy samples, respectively; after which, the D peak starts decreasing with increase in fluence. For irradiated samples we systematically investigate structural changes in SiC substrate as well as EG. Raman spectroscopy results shows that at low fluence, point defects are generated and formation of amorphization nuclei and coalescence of amorphous domain occurs at higher fluence. In addition, ion irradiation did not result in structural phase transformation since signature of any other SiC polytype was not observed. We observed carbon nanodots in both irradiated samples. In case of 30 keV silver irradiated sample, we have observed maximum concentration of carbon nanodots at fluence 1× 1013 ions/cm2. In case of high energy irradiated samples, we have observed also wrinkles and folding in the EG, which was not observed in low energy irradiated samples. Further, we have done gas sensing on the samples in ppb and ppm range of NH3 and NO2 gas, preliminary results show an increase in gas sensing and the work is currently in progress. This study opens a new platform for tailoring surface of EG for various sensing applications.
Authors : Vikas Rana1 and Rainer Waser1,2
Affiliations : 1Peter Grünberg Institute-7, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany 2IWE II, RWTH Aachen University, 52074 Aachen, Germany
Resume : Redox-based resistive random access memory (ReRAM) has shown low power consumption, fast switching speed and ultra-dense integration capability . However, one time electroforming process, that is required to initiate the switching process, consumes more power than that of switching cycles. The higher power consuming step makes these devices incompatible to low-voltage CMOS technology. Therefore, it is important to have forming-free ReRAM devices. In this talk, we show the impact of ion-implantation process on the forming voltage and other resistive switching properties. The Forming-free ReRAM devices can be obtained by the ion-implantation of different dopants in binary metal-oxide thin-film during the device fabrication process. These forming free devices show very high endurance and retention . Besides their potential as memory, the ReRAM devices in crossbar configuration offer implementation of memory-intensive computing paradigm and adds an extra edge to this technology. With multi-level switching capability, an intrinsic modular arithmetic using a ternary number system will be presented. This opens up the computing space beyond traditional binary values . References . R. Waser, V. Rana, S. Menzel and E. Linn, “Energy-efficient Redox-based Non-Volatile Memory Devices and Logic Circuits,” 3rd Berkeley Symposium on Energy Efficient Electronic Systems, vol., pp. 1-2, 2013. . W. Kim, A. Hardtdegen, C. Rodenbücher, S. Menzel, D. J. Wouters, S. Hoffmann-Eifert, D. Buca, R. Waser and V. Rana, “Forming-Free Metal-Oxide ReRAM by Oxygen Ion Implantation Process,” 2016 IEEE International Electron Devices Meeting (IEDM), San Francisco, USA, December 3-7, 2016, 2016, pp. . W. Kim, A. Chattopadhyay, A. Siemon, E. Linn, R. Waser and V. Rana, “Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic,” Sci. Rep., vol. 6, pp. 36652, 2016
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Catalytic Nanomaterials : Jost Adam, Rosaria Puglisi
Authors : Shashank Mishra
Affiliations : Claude Bernard University of Lyon1, IRCELYON, 2 Avenue A. Einstein, 69626 Villeurbanne, France
Resume : Industrial development of chemical solution and vapor routes to inorganic nanomaterials (e.g., sol-gel, MOD, MOCVD…) is strongly dependent on the molecular engineering that involves design of tunable metal-organic precursors having desirable properties. These molecular precursors are usually the starting point of the processes that influence the micro- & nano-structure and, therefore, the nature and the properties of the obtained materials.1-4 The use of well-defined precursors and isolation of molecular intermediates during molecules-to-nanoparticles transformation also allows to establish relationships between precursors and the final material and, therefore, to get some insight in to their transformation. This presentation will address different concepts of the ‘bottom-up’ approach of the synthesis of inorganic nanomaterials with a special emphasis placed on the design of homo or heterometallic (‘single-source’) precursors should have (i) a formulation that matches well with that of the final materials, particularly stoichiometry of metals for multimetallic materials, (ii) appropriate physicochemical properties (solubility, thermal stability, volatility…), (iii) the required chemical functionalities (coordination sphere with an appropriate set of ligands), and (iv) a clean, low temperature conversion into nanomaterials with minimized undesired residues in the end. Different catalytic applications of the obtained nanomaterials will be described. Keywords: molecular precursor, nanomaterials, Sol-Gel, metal-organic decomposition, metal oxide, metal selenide nanoparticles, metal fluoride composites, photocatalysis REFERENCES  S. Mishra, S. Daniele, Metal-organic derivatives with fluorinated ligands as precursors for inorganic nanomaterials, Chem. Rev. 2015, 115, 8379-8448.  a) S. Mishra, F. Morfin, V. Mendez, P. N. Swamy, J.-L. Rousset, S. Daniele, Nanometric NaYF4 as an unconventional support for Gold catalysts for oxidation reactions, ACS Omega, 2019, 4, 5852−5861; b) Y. Chen, S. Mishra, G. Ledoux, E. Jeanneau, M. Daniel, J. Zhang, S. Daniele, Direct synthesis of hexagonal NaGdF4 nanocrystals from a single-source precursor: Upconverting NaGdF4:Yb3+,Tm3+ and its composites with TiO2 for near-IR-driven photocatalysis. Chem. Asian J., 2014, 9, 2415‒2421.  a) S. Gahlot, E. Jeanneau, F. Dappozze, C. Guillard, S. Mishra, Precursor-mediated synthesis of Cu2-xSe nanoparticles and its composites with TiO2 for improved photocatalysis, Dalton Trans. 2018, 47, 8897–8905; b) S. Mishra, D. Du, E. Jeanneau, F. Dappozze, C. Guillard, J. Zhang, S. Daniele, A facile molecular precursor-based synthesis of Ag2Se nanoparticles and its composites with TiO2 for enhanced photocatalytic activity, Chem. Asian J. 2016, 11, 1658-1663.  a) S. Mishra, E. Jeanneau, S. Mangematin, H. Chermette, M. Poor Kalhor, G. Bonnefont, G. Fantozzi, S. Le Floch, S. Pailhese, S. Daniele, A convenient and quantitative route to Sn(IV)–M [M = Ti(IV), Nb(V), Ta(V)] heterobimetallic precursors for dense mixed-metal oxide ceramics, Dalton Trans., 2015, 44, 6848–6862; b) S. Mishra, V. Mendez, E. Jeanneau, V. Caps, S. Daniele, A single source precursor route to group 13 homo- and heterometal oxides as highly active supports for gold catalyzed aerobic epoxidation of t-stilbene, Eur. J. Inorg. Chem., 2013, 500‒510.
Authors : Luigi Ranno, Stefano Dal Forno, Johannes Lischner
Affiliations : Imperial College London
Resume : Computational design can accelerate the discovery of new materials with tailored properties, but applying this approach to plasmonic nanoparticles with diameters larger than a few nanometers is challenging as atomistic first-principles calculations are not feasible for such systems. To overcome this challenge, we have developed a novel material-specific approach that combines effective mass theory for electrons with a quasistatic description of the localized surface plasmon to identify promising bimetallic core-shell nanoparticles for hot-electron photocatalysis. Specifically, we have calculate hot-carrier generation rates of 100 different core-shell nanoparticles and find that systems with an alkali-metal core and a transition-metal shell exhibit high figures of merit for water splitting and are stable in aqueous environments. Our analysis reveals that the high efficiency of these systems is related to their electronic structure, which features a two-dimensional electron gas in the shell. Our calculations further demonstrate that hot-carrier properties are highly tunable and depend sensitively on core and shell sizes. The design rules resulting from our work can guide experimental progress towards improved solar energy conversion devices.
Authors : Benedykt R. Jany, Arkadiusz Janas, Franciszek Krok
Affiliations : Institute of Physics, Jagiellonian University, Lojasiewicza 11, PL30384 Krakow, Poland
Resume : Scanning Electron Microscope (SEM) is nowadays basic accessible tool for materials characterization at nanoscale. SEM microscope is usually equipped with Energy Dispersive X-ray Spectroscopy (EDX) system which is used for quantitative chemical analysis. Due to the electron beam interaction with matter the X-ray generation volume is of the order of micrometer, which limits the spatial resolution of EDX. In the presentation the results of quantitative chemical analysis of metallic nanostructures resulted from thermally induced self-assembly of thin Au layer (few monolayers) deposited on various semiconductor surfaces i.e. Ge(001), InSb(001) will be shown. This leads to formation of Au-rich nanostructures with size of ~50nm. For each surface morphology hyperspectral EDX data were collected, where in each pixel full EDX spectrum was recorded. Next by using Machine Learning Blind Source Separation the EDX signal coming from nanostructures was separated from the signal of bulk semiconductor. This allowed for chemical composition quantification of formed nanostructures by EDX ZAF method [1,2]. The presented approach breaks the spatial limit of the EDX method and allows for chemical composition quantification of various nanomaterials by using affordable and accessible SEM/EDX instead of TEM measurements.  B.R. Jany et al., Nano Lett., 2017, 17 (11), pp 6520–6525  B.R. Jany et al., Collected SEM EDX data at nanoscale together with analysis program, doi:10.13140/RG.2.2.19558.93763
Authors : Sawsan Almohammed [a, b], Sebastian Tade Barwich [c], Andrew K. Mitchell [a], Brian J. Rodriguez [a, b], and James H. Rice [a]
Affiliations : a School of Physics, University College Dublin, Belfield, Dublin 4, Ireland b Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland c School of Physics, Trinity College Dublin, Dublin 2, Ireland
Resume : The development of new catalysts for oxidation reactions is of central importance for many industrial processes. Plasmonic catalysis involves photoexcitation of templates/chips to drive and enhance oxidation of target molecules. Raman-based sensing of target molecules can also be enhanced by these templates. This provides motivation for the rational design, characterization, and experimental demonstration of effective template nanostructures. In this work, we study a template comprising of silver nanoparticles present on aligned peptide nanotubes, contacted with a microfabricated chip in a dry environment. This template enables efficient plasmonic catalysis activated and controlled by application of an electric field. Raman detection of biomolecules are also dramatically enhanced by the template. We demonstrate that this optoelectrical device enhances photocatalytic conversion for model oxidation reactions exploiting the facile field-activated trans-template charge transfer. We also demonstrate that this same approach can be used to enhance the strength of Raman scattering from low Raman cross-section molecules such as glucose and DNA-based molecules, establishing the potential of our template design for sensitive detection and analytics. Reference Enhanced photocatalysis and biomolecular sensing with field-activated nanotube-nanoparticle templates. Nature communications, in press.
Authors : O. Diwald1, J. Schneider1, A. Ziegler1, T. Berger1, P. Dzik2;
Affiliations : 1: Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, A-5020 Salzburg; 2: Fakulta Chemická, VUT v Brně, Brno University of Technology, Czech Republic
Resume : The efficient functionalization of metal oxide nanostructures with organic dyes is a prerequisite to achieve hybrid materials for dye-sensitized solar cells, sensors or photocatalytic devices. The stability of these materials in the ambient, e.g. in the presence of ubiquitous gaseous water, plays an important role during production and operation. Starting from gas-phase grown TiO2 anatase nanoparticles (~12 nm) we produced thin TiO2 films by inkjet printing. Powders and thin films were functionalized with 2H-Tetraphenylporphyrin (2HTPP) in the gas phase under high vacuum conditions. In the course of these experiments we added gaseous water before or after porphyrin adsorption. The influence of surface hydroxyls on the porphyrin adsorption process and the stability of the hybrid material in aqueous environment was addressed by tracking porphyrin adsorption and consecutive surface reactions by UV/Vis absorp-tion and photoluminescence emission spectroscopy. Significant crystal modification related differences in porphyrin adsorption can be observed for the anatase and ru-tile samples. Furthermore, the surface protonation reactions of adsorbed porphyrin molecules upon formation of 4HTPP2 species was observed, while 2HTPP adsorp-tion on hydroxylated TiO2 surfaces shows no significant change.[2,3] Literature:  Ardo, S., Meyer, G.J. Chem. Soc. Rev., 2009, 38, 115  Schneider, J., et al. ACS Appl. Mater. Interfaces 2018, 10, 16836  Schneider, J., et al. in preparation
Authors : C. X. Zheng, K. Hannikainen, Y. R. Niu, J. Tersoff, J. Pereiro, D. Gomez, and D. E. Jesson
Affiliations : ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Clayton, Victoria, Australia; School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom; School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom; IBM T. J. Watson Research Center, Yorktown Heights, New York, USA; School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom; School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom; School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom;
Resume : We combine droplet epitaxy with low energy electron microscopy imaging techniques to map the surface phase diagram of GaAs(001). The droplet epitaxy phase patterns produced are interpreted using a simple model which links the spatial coordinates of phase boundaries to free energy. It is thereby possible to gain important new information on surface phase stability, based on the observed sequential order of the phases away from the droplet edge. This can be used to improve existing phase diagrams generated by density functional theory calculations. We establish the existence of a (3x6) phase and confirm, that the controversial (6x6) is thermodynamically stable over a narrow range of chemical potential.
Authors : Doludenko I.1, Zhigalina O.1, Khmelenin D.1, Kanevski V.1, Zagorskiy D.1, Cherkasov D., Biziaev D.2, Khaibullin .R2, Shatalov A.1
Affiliations : 1 Center of Crystallography and Photonics of RAS, Moscow, Russia 2 Kazan Institute of Physics and Technology. E. K. Zavoisky Kazan Scientific Center of RAS, Kazan, Russia
Resume : Layered nanowires (NWs), consisted of alternating layers of magnetic and nonmagnetic metals, seems promising for GMR, elements for microelectronics and spintronics. Track membranes (PET films, pores diameter 50-200 nm and density 10 8) were used as templates. Layered NWs Ni/Cu and Co/Cu were obtained using the solutions of corresponding salts and pulsed deposition. TEM measurements were made: thickness and elemental compositions of NWs were determined. It was shown that copper layers consist of pure Cu (Fm3m), while Ni layers (Fm3m) or Co layers (hex.) always include Cu admixture (up to 15-20%). Two fractions of crystallites were found (size 5-10 nm and up to 100 nm). (These data was in accordance with X-rays investigations). Passed-charge control gave better homogeneity of layers that pulse-time control. It was also shown that reduction of layer’s thickness is effective down to 20 nm. For “thinner” layers interfaces between them became irregular and metal distribution between layers became irregular. Another result of reducing the deposition time was formation of “core-stick” structure. Magnetic measurements demonstrate that NWs with thick layers (higher than 100 nm) demonstrate high magnetic anisotropy, while NWs with thin layers (50-100 nm) were isotropic. Magnetic Force microscopy of the single NW were carried out in two geometries – for NW’s top and for horizontal NW. The effect of external magnet (16 mT) on magnetization reversal was demonstrated. The influence of NWs on each other was also shown – only part of NWs could change their magnetization Another approach - “double-bath” method was also used and compared with commonly used “single-bath” technique. Acknowledgements. State Task of FNIC “Crystallography and Photonics” of RAS.
Perovskite Nanomaterials : Rosaria Puglisi, Jean-Claude Grivel
Authors : Quentin Micard, Gugliemo G. Condorelli, Graziella Malandrino
Affiliations : Dipartimento di Scienze Chimiche, Università degli Studi di Catania, INSTM UdR Catania Catania 95125, Italy
Resume : Inorganic perovskites are key materials for many technologies going from high Tc superconductors, to high-k dielectrics, from piezoelectric to colossal magnetoresistance materials, from ionic conductors to multiferroics. Perovskites are compounds with ABX3 formula where the anion X form together with A a cubic compact packing, thus A is twelve coordinated, while B, occupying the octahedral holes, has a six-coordination. The countless potentialities of perovskites arise from the possibility to dope both the A and B sites giving rise to a great variety of compositions and properties. In this presentation, a simple synthetic strategy based on metal organic chemical vapor deposition (MOCVD) for the fabrication of inorganic perovskite thin films will be presented. Depositions have been realized in a customized hot wall reactor, employing argon as a carrier gas and oxygen as a reactant gas. Multicomponent mixtures consisting of appropriate β-diketonates have been used as precursor sources. Films have been grown on conventional and conducting substrates of 10 mm x 10 mm surface. Some case studies will be reported with particular attention to the ferromagnetic manganites and the piezoelectric/ferroelectric bismuth ferrite. Part of this work is supported by the European Community under the Horizon 2020 Programme in the form of the MSCA-ITN-2016 ENHANCE project, Grant Agreement N.722496.
Authors : Duong Nguyen Minh, Youngjong Kang
Affiliations : Department of Chemistry, Research Institute for Natural Sciences, Institute of Nano Science and Technology, Hanyang University
Resume : On account of their exceptional electronic and optical properties, organometal halide perovskite materials have been extensively explored in the various optoelectronic applications for last few years. Recently, alkylammonium lead halide perovskite nanoparticles also received considerable attention as active materials for LEDs. In the LED applications, alkylammonium lead halide perovskite nanoparticles exhibit superior optical properties such as high color purity with narrow band width, broad color tunability covering entire visible region either by varying halide composition or particle size, and almost unity photoluminescence quantum yield (PLQY). However their practical applications are often hindered by the poor stability of perovskite materials against water and polar solvents. Additionally, patterning technology of perovskite materials is highly demanded for creating the high resolution pixels. As a way of addressing above mentioned problems, perovskite nanoparticle composite films have been fabricated by using size-exclusive mass-flow lithography Perovskite nanoparticle composite films with capability of high-resolution patterning (≥ 2 µm) and excellent resistance to various aqueous and organic solvents have been prepared by in situ photosynthesis of acrylate polymers and formamidinium lead halide (FAPbX3) nanoparticles. Both positive- and negative-tone patterns of FAPbX3 nanoparticles are created by controlling the size-exclusive flow of nanoparticles in polymer networks. The position of nanoparticles is spatially controlled in both lateral and vertical directions. The composite films show high PLQY (up to 44%) and broad color tunability in visible region (λpeak = 465-630 nm).
Authors : Emanuele Smecca, Ajay Jena, Ioannis Deretzis, Gyu Min Kim, Yohuei Numata, Giovanni Mannino, Corrado Bongiorno, Antonino La Magna, Tsutomu Miyasaka and Alessandra Alberti.
Affiliations : CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy; Toin University of Yokohama, Graduate School of Engineering, 1614 Kuroganecho, Aoba, Yokohama, 225-8503, Japan; CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy; Toin University of Yokohama, Graduate School of Engineering, 1614 Kuroganecho, Aoba, Yokohama, 225-8503, Japan;Toin University of Yokohama, Graduate School of Engineering, 1614 Kuroganecho, Aoba, Yokohama, 225-8503, Japan; CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy; CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy; CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy; Toin University of Yokohama, Graduate School of Engineering, 1614 Kuroganecho, Aoba, Yokohama, 225-8503, Japan; CNR-IMM Zona industriale, Strada VIII 5, 95121, Catania, Italy;
Resume : It is undoubted that organic-inorganic hybrid perovskites have been representing a scientific breakthrough in the photovoltaic field since 2009 when they were applied to replace photoactive dyes in hybrid solar cells. Further development has been highly boosted by a large and enthusiastic effort of the worldwide scientific community to improve the response to sun light. The current certified maximum efficiency is 23.7%. The exceptionality of this class of materials resides in their soft nature. The long diffusion lengths of the photo-generated carriers, the wide absorption range, the direct and tunable bandgap are mainstays. It is equally true that the low structural stability of the hybrid perovskites, primary MAPbI3, risks to severely retard their wide-range applications in low cost/high yield devices. A large effort is consequently needed to frame the instability sources and degradation mechanisms in relationship with the operation conditions, including temperature, illumination, humidity, contaminants and boundary materials in the final architecture. One of the most used strategies is this perspective is the changing or mixing different cations, (MA+, FA+ and Cs+) to improve the lattice stability. Although the overall scenario is brighter than years ago, reliable and long-lasting solutions to avoid back-reaction of perovskites to the starting organic and inorganic components and indeed to extend cell durability are under spotlight. For the market uptake, moreover, device architectures, to be produced via simple and sequential steps, being free of contaminants and at low environmental impact, are warmly encouraged to catch the interest of investors. A critical analysis of the available data indicates that degradation under ambient conditions is a defect-generation process that is highly localized on surfaces and interfaces, while it is further enhanced above the tetragonal-cubic transition at ∼54 °C. Within this context, we discuss the conservative role of N2 and propose strategies for the emergence of industrially viable hybrid photovoltaics. The paper will thus frame strengths and weaknesses of hybrid perovskites for next-generation photovoltaics in view of their extended use and dissemination in daily life.
Authors : ShinYoung Jeong, Soon-kyu Cha, Byeoung-Kwon Ju and IlKi Han
Affiliations : Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul, Korea; Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul, Korea; School of Electrical Engineering, Korea University, Seoul, Korea; Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul, Korea
Resume : As displays and imaging technologies become more sophisticated, advances in sensor technology that make up the camera also have become indispensable. Recently, as the importance of image sensors used for automatic driving in automobile industry becomes more important, not only the resolution but also the response speed of the sensor has become an issue to be surely improved. In this study, we fabricated quantum dot (QD) based vertical type photodiodes by using ZnO and MoOx as electron and hole transport layers, respectively. Rising and falling times were measured to be τr = 28.8 ± 8.34ns and τf = 40 ± 9.81ns. Comparing with previous results with the transit time of 300 ns, our QD photodiodes show practical potential for applications. Such high-speed operation is due to metal oxide and ligands which make easier to extract carriers at interface between ZnO and QDs and will be presented in more details. This work was supported by Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (NRF-2013M3C1A3065033) and the Future Resource Program (2E29300) of Korea Institute of Science and Technology (KIST).
Authors : R.I. Eglitis, A.I. Popov, J. Purans, R. Jia
Affiliations : Institute of Solid State Physics, University of Latvia, 8 Kengaraga str., Riga LV1063, Latvia
Resume : The atomic displacement magnitudes of nearest neighbor atoms around the (001) surface F-center in ABO3 perovskites are considerably larger than the related displacement magnitudes of nearest neighbor atoms around the bulk F-center. In the ABO3 perovskites the electron charge is considerably better localized inside the bulk F-center than in the (001) surface F-center, where the oxygen vacancy charge is more delocalized over the nearest neighbor atoms than in the bulk F-center case. The (001) surface F-center formation energy in the ABO3 perovskites is smaller than the bulk F-center formation energy, which triggers the F-center segregation from the ABO3 perovskite bulk towards its (001) surfaces. In most cases the (001) surface F-center induced defect level in the band gap of ABO3 perovskites is located closer to the (001) surface conduction band bottom than the bulk F-center induced defect level to the bulk conduction band bottom [1-3]. In contrast to ABO3 perovskite bulk and (001) surface F-centers, the CaF2, BaF2 and SrF2 bulk and surface F-center charge is very well localized inside the fluorine vacancy. The atomic relaxation magnitudes around both bulk and surface F-centers in CaF2, BaF2 and SrF2 crystals, as a rule, are considerably smaller than the relevant atomic relaxation magnitudes around bulk and (001) surface F-centers in ABO3 perovskites [4,5]. References: 1. R.I. Eglitis and A.I. Popov, J. Nano-Electron. Phys. 11, 01001 (2019) 2. R.I. Eglitis and S. Piskunov, Comput. Condens. Matter 7, 1-6 (2016) 3. M. Sokolov, R.I. Eglitis, S. Piskunov, Y.F. Zhukovskii, Int. J. Mod. Phys. B 31, 1750251 (2017) 4. H. Shi, R.I. Eglitis, G. Borstel, Phys. Rev. B 72, 045109 (2005) 5. H. Shi, R. Jia, R.I. Eglitis, Solid State Ionics 187, 1-7 (2011)
|15:30||Coffee / Tea Break|
Perovskite Nanomaterials : Yogendra Mishra, Malandrino Graziella
Authors : Maria Vasilopoulou
Affiliations : Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Terma Patriarchou Grigoriou, 15310, Agia Paraskevi, Greece
Resume : Inserting suitable interfacial materials between the photoactive layer and the selective contacts in organic semiconductor (OSC) and perovskite (PeSC) materials based solar cells has become one of the most important strategies to enhance charge extraction and suppress charge recombination in both types of solar cells. Here, we systematically engineer the cathode interfaces of OSCs and PeSCs by using molecular materials such as porphyrins, pyrenes, polyoxometalates and others all bearing functional groups, including carboxyl, amine, isopropyl, phenethyl and tert-butyl-phenethyl groups, and study their electron extracting/surface passivation capability. The main outcome of this study is that the judicious control of the interaction between organic semiconductor/perovskite surface and molecules can realize effective electron extraction through the reduction of the electron extraction barrier and surface passivation both leading to significant device performance.
Authors : R. Gegevičius a), A. Devižis a), A. Fakharuddin b), A. Kadaschuk c), V. Gulbinas a)
Affiliations : a) Center for Physical Sciences and Technology, Saulėtekio av.3, LT-10257 Vilnius, Lithuania; b) Imec, Kapeldreef 75, 3001, Leuven, Belgium; c) Institute of Physics, Prospect Nauky 46, 03028 Kyiv, Ukraine
Resume : Metal halide perovskites, initially emerged as effective materials for solar cells, are currently also attempted to use for other devices such as photodetectors and light emitting diodes, lasers. However, despite many unique advantages perovskites also have some undesirable features which still limit their applications. Performance of both photovoltaic and electroluminescent devices suffers from non-radiative recombination losses related to carrier traps. The trapping influence has been demonstrated to be reduced in perovskite nanocrystals, or in hybrid quasi-two-dimensional (2D) perovskites, due to the spatial carrier confinement. Here, by using ultrafast spectroscopy and transient electroluminescence (EL) techniques, we addressed charge carrier dynamics in 2D perovskite-based LEDs. In particular we demonstrate that 3D domains present in 2D perovskite rapidly trap carriers of one type preventing trap-assisted nonradiative recombination in host 2D material. EL dynamics under device pumping by short electrical pulses, revealed importance of spatial electron and hole distributions within perovskite layer in determining the EL efficiency. Weak overlap of electron and hole distributions diminish radiative carrier recombination rate, and are partly responsible for the efficiency roll-off of perovskite LEDs at high current densities. Strong EL pulse, known as EL overshoot, was observed after voltage switch-off. The overshoot effect suggests an unconventional way to achieve high-pulsed electroluminescence intensity with a low current density, which opens new prospects towards optical gain and implementation of electrically pumped lasers.
Authors : Bin Xin†, Naresh Alaal†, Somak Mitra†, Ahmad Subahi‡, Yusin Pak†, Norah Alwadai†,§, Iman S. Roqan†*
Affiliations : † Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia ‡ King Saud Bin Abdulaziz University for Health Sciences, Jeddah 22384, Saudi Arabia § Department of Physics, College of Sciences, Princess Nourah bint Abdulrahman University (PNU), Riyadh 11671, Saudi Arabia
Resume : Perovskite has been emerged as an active layer for such devices, due to its low cost, low-temperature solution processing, and outstanding performance. The beneficial characteristics of perovskite is high illumination, highly sensitive response to visible/UV light prevents perovskite use as an active material for X-ray detectors due to the interference with UV/visible light as indirect semiconductor is the typical material for X-ray detector to avoid such noise. In this work, we explore indirect bandgap perovskite, for the first time, that it is not suitable for light absorption in contrast of other perovskites, however, it is ideal for practical perovskite based x-ray as it does not have light interference noise, allowing to detect x-ray only with higher sensitivity than that of commercial ones. We used theoretical studies and several experimental investigations using time-resolved spectroscopy to demonstrate the bandgap structure. Different inorganic perovskites of four CsPbX3 (X = I, Br) nanocrystals are synthesized by novel method. Their XRD measurements imply that the direct bandgap CsPbBr3 cubic phase and the CsPbI3 orthorhombic yellow δ-phase. No other phases are shown, confirming high structural quality. Transmission electron microscopy is used to confirm the structural properties of the materials. The X-ray detector based on the indirect bandgap CsPbI3 perovskite reaches a sensitivity of 83.6 μCGyair-1cm-2 (which is superior compared to commercial x-ray detectors) using a very thin (6.6 μm) active layer, which is essential for device miniaturization. The devices based on indirect bandgap CsPbI3 show very weak performance under visible light compared to the direct bandgap CsPbBr3, eliminating the interference noise.
Authors : Il-Wook Cho and Mee-Yi Ryu
Affiliations : Department of Physics, Kangwon National University, Chuncheon, Korea
Resume : Methylammonium lead halide perovskites (CH3NH3PbX3, where X = Cl-, Br-, I-) have attracted attention as prospective materials for optoelectronic devices due to the many advantages such as tunable bandgap, high electron/hole mobilities, and low-cost solution processing. However, solution processed perovskite (PS) holds defect states such as grain boundaries and/or film surface, and the instability of PS films in humidity remains the most important issue to be overcome. Therefore, suppressing these defect states and improving stability are key factors for development of PS-based devices with high-performance and long-term stability. Surface passivation is a general solution for reducing charge traps induced by structural defects and for protecting surface from moisture in air. In this paper, we present the charged carrier transport (CT) phenomenon in surface-passivated PS films by CdSe/ZnS quantum dots with different dot sizes. The CT process between mixed halide PS and CdSe/ZnS core-shell quantum dots (QDs) has been investigated by using photoluminescence (PL) and time-resolved PL. The diameter of QDs used in this studywas varied from 2.7 to 6.5 nm. The QD/PS hybrid structure samples exhibited much stronger PL intensities and longer PL decay times compared with that of pristine PS sample. The enhanced PL intensity and lengthened decay time in QD/PS hybrid structureare attributed to the CT from QDs to PS. As a core diameter of CdSe/ZnS QDs decreases from 6.5 to 2.7 nm, the CT efficiency in QD/PS hybrid structures also varied from 5 % to 56 % due to the enhancement of CT rate caused by the control of energy-level alignment of QDs. These results allow us to understand the fundamental mechanism such as CT process from QDs to PS as a function of size of QDs.
Authors : Zh.V. Smagina (1), V.A. Zinovyev (1), E.E. Rodyakina (1,2), A.V. Nenashev (1.2), M.V. Stepikhova (3), A.N. Yablonskiy (3), A.V. Novikov (3), A.V. Dvurechenskii
Affiliations : 1) Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia. 2) Novosibirsk State University, 630090 Novosibirsk, Russia. 3) Institute for Physics of Microstructures Russian Academy of Sciences, 603950 Nizhny Novgorod, Russia.
Resume : Ge/Si heterostructures with self-assembled quantum dots (QDs) are considered as one of the possible means for creating silicon-based light-emitting devices. Advantages of these structures are a relative simplicity of their formation and a room-temperature luminescence in the range 1.3?1.6 ?m. However, a significant disadvantage of such light-emitting structures is low efficiency of radiative recombination. This problem can be resolved by embedding GeSi QDs into microresonators, including those based on two-dimensional photonic crystals (PhCs). We consider various approaches to integrating ordered GeSi QD arrays into resonators based on two-dimensional photonic crystals and present the luminescent properties of the structures obtained. We used the Ge/Si structures with QDs grown on the pre-patterned surface. Creation of ordered arrays of QDs solves the problem of amplification of the emission from QDs by precise embedding them into microcavities, based on PhCs, where the quantum dots are located in positions of maximum concentration of the electric field. For structures with PhCs formed on arrays of ordered QDs, an increase in the PL intensity at room temperature in the range 0.9 ÷ 1.2 eV was detected, which is associated with the interaction of the structure radiation with the modes of the PhCs. Parameters of the PhCs are experimentally determined for the interaction of the QDs radiation with the radiation modes of the PhC itself as well as the microcavity created in the PhC.
Authors : Liang Hu, Yu-Jia Zeng, Juanmei Duan
Affiliations : Shenzhen Key Laboratory of Laser Engineering, College of Physics and Optoelectronic Engineering, Shenzhen University, Nanhai Avenue 3688, 518060 Shenzhen, P. R. China (L. Hu, Y. Zeng); Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany (J. Duan)
Resume : Semiconductors with low dimensional feature can display remarkably optical, electrical and magnetic advantages over their bulk counterparts. Within the scope of low dimensions (0D, 1D and 2D), the control of doping, assembly and stability of materials appears more challenging, if possible, which can better serve us to understand some abnormal physical and chemical phenomenon and further explore novel application ways in nanoelectronics and nanophotonics. In this talk, for different application scenarios, popular VA-group 2D elemental semiconductors (mainly phosphorene and antimonene) are employed to demonstrate the possibility of tailoring their functional properties. Similar to graphene, the elements from the VA-group (or pnictogen group) can also form 2D materials. Black phosphorus (BP) has an orthorhombic and layer-dependent direct band structure, which lead to the development of several thinning strategies including micro-mechanical and liquid exfoliation. However, the oxidation of BP can easily happen and is often considered as a synergistic role of oxygen and water. In general, the chemical functionalization is an effective way to overcome such a problem but cannot keep for a long time. Herein, we have first utilized inorganic semiconductor zinc oxide (ZnO) to fabricate type-I and -II heterostructures and compared different stabilization mechanisms. Based on a flexible self-assembly strategy, different 0D/0D and 0D/1D combinations composed by ZnO and BP can be formed and contribute to distinct device performances including photodetection, resistive memory and surface enhanced Raman scattering (SERS). Compared to BP, rhombohedral structured antimony exhibits a stronger interlayer covalent interaction and a significant disadvantage in single and few-layer material synthesis. On the other aspect, its monolayer type (antimonene) has an indirect band structure and has not been experimentally utilized to develop transistor device. So in this talk, we will introduce an electrochemical exfoliation and synchronous doping technique to prepare them. By choice of Na and F doping elements, direct bandgap and magnetic antimonene can be obtained, respectively, shielding light on its potential for optoelectronic and spintronic applications. References:  Liang Hu, Yu-Jia Zeng,* et al. Black Phosphorus Quantum Dots with Tunable Memory Properties and Multilevel Resistive Switching Characteristics, Advanced Science 2017, 4, 1600435.  Liang Hu, Yu-Jia Zeng,* et al. Phosphorene/ZnO Nano-Heterojunctions for Broadband Photonic Nonvolatile Memory Applications, Advanced Materials 2018, 30, 1801232.  Liang Hu, Yu-Jia Zeng,* et al. Charge Transfer Doping Modulated Raman Scattering and Enhanced Stability of Black Phosphorus Quantum Dots on a ZnO Nanorod, Advanced Optical Materials 2018, 6, 1800440.  Liang Hu, Yu-Jia Zeng,* et al. Robust Above-Room-Temperature Ferromagnetism in Few-Layer Antimonene Triggered by Nonmagnetic Adatoms, Advanced Functional Materials 2019, 29, 1808746.
Authors : K. Shportko, E. Venger.
Affiliations : V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine, Kyiv, Ukraine
Resume : (GeTe)x(Sb2Te3)1-x alloys belong to the class of phase-change materials are among the most promising functional materials for new data storage and data visualization concepts. In (GeTe)x(Sb2Te3)1-x the optical dielectric constant is 70–200% larger for the crystalline than for the amorphous phases. These materials provide evidence for a disorder-driven metal–insulator transition. Furthermore, crystallization in these materials can be extremely rapid and can occur in less than 100 ns. In the present work, we studied the fluctuations of the absorption around the fundamental absorption edge in some (GeTe)x(Sb2Te3)1-x alloys. This study is aimed to reveal the correlation between the structure and optical properties of studied alloys in this range. We studied the absorption edge fluctuations that are linked to the variations of the bandgap, the width of localised electronic states, the Tauc parameter, and average halfwidth of Raman bands in some (GeTe)x(Sb2Te3)1-x alloys.
Poster Session : Yogendra Mishra, Jean-Claude Grivel, Jost Adam, Rosaria Puglisi
Authors : Jean-Claude Grivel
Affiliations : Technical University of Denmark
Resume : Mg, Cu and/or rare-earth elements doped ZnO films were prepared on glass substrates using water based coating solutions. Their efficiency in view of water purification by means of photocatalysis was evaluated on various industrial dyes including methyl violet, brilliant blue, methylene blue, malachite green, brilliant green, phenol red, rhodamine B and crocein scarlet. The solutions were based on either demineralised water or natural seawater. Besides using a UV lamp as an irradiation source, direct solar illumination was also studied as a preliminary test for field applications. Regeneration of the films after several runs was investigated using heat treatments coupled with studies of the thermal decomposition process of the dyes and their degradation products.
Authors : D. Kuhness(1), J. Sattelkow(1), R. Winkler(1), H. Plank(1,2,3)
Affiliations : 1) Christian Doppler Laboratory - DEFINE, Graz University of Technology, 8010 Graz, Austria; 2) Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, 8010 Graz, Austria; 3) Graz Centre for Electron Microscopy, 8010 Graz, Austria
Resume : In the last decade, the area of nano-plasmonics has attracted increasing interest for real applications such as directed nano-emitters or high-performance sensors. While traditional fabrication, such as electron beam lithography, provides very high lateral resolution, they are often limited to flat surfaces. To overcome this limitation, additive direct-write methods are ideal candidates, although techniques for reliable sub-100 nm fabrication are only few. Focused electron beam induced deposition (FEBID) is one of the promising technologies, which not only meets the resolution requirements but also allows true 3D nano-printing on almost any material and surface morphology. In a previous study, we used FEBID for fabrication of plasmonically active, freestanding 3D architectures with sub-30 nm branch diameters composed of pure gold. Although gen-erally successful, we found two aspects, which require further research to exploit the full potential of this approach. First, individual branches revealed a certain side wall roughness and slightly conical shapes. Second, the required purification step after ini-tial fabrication affects the antenna morphology even further, which leads to a reduced plasmon resonance performance compared to traditionally fabricated nano-structures. Based on this situation, we here present our latest activities towards highest shape fi-delity of 3D nano-pillars including the material transfer into pure Au nano-antennas for high-performance 3D nano-plasmonics.
Authors : Nataliia Kurgan, Volodymyr Karbivskyy
Affiliations : G.V. Kurdyumov Institute for Metal Physics NAS of Ukraine
Resume : In this work shows the results of producing nanowires based on tobacco mosaic virus (TMV) and gold nanoparticle, which are perspective object for nanotechnology . New method was developed for nanowires preparation based on citrate method synthesis of metal nanoparticles and includes the preparing of the metal source and reductant stock solutions and the gold recovery process through several cycles of mixing solutions, in the presence of the purified and modified TMV. A study of the physicochemical properties and the morphology of the nanowires were carried out by atomic force microscopy and X-ray photoelectron spectroscopy. The hybrid bio-inorganic virally-gold structure was about 50 nm in diameter and 150-400 nanometers in length. Uncoated gold TMV virions were not detected. It was found that the nanowires prefer to cluster ordering. Its interaction with the substrate is characterized by С–N bond, while the bond N-C=O is characterized by binding virions with each other. The electronic Au 4f core levels demonstrate shift towards lower binding energy at nanowires formation. It has been established that the obtained nanowires have optical activity with a maximum at 540 nm. The studies will be perspective to produce nanomaterials based on plant viruses and metal nanoparticles for nanoelectronics. . X.Z.Fan et al. Tobacco mosaic virus: A biological building block for micro/nano/bio systems // J. Vac. Sci. Technol. A 31, 050815 (2013).
Authors : N. Nepomniashchaia, D. Chvostova, V. Vetokhina, A. Dejneka, M. Tyunina
Affiliations : Institute of Physics of the Czech Academy of Sciences, Na Slovance 2,182 21 Prague 8, Czech Republic and Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Technicka 2, 166 27 Prague 6, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Na Slovance 2,182 21 Prague 8, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Na Slovance 2,182 21 Prague 8, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Na Slovance 2,182 21 Prague 8, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Na Slovance 2,182 21 Prague 8, Czech Republic and Microelectronics Research Unit, University of Oulu, P.O. Box 4500, FI-90014, Oulu, Finland
Resume : One of the key points in development of thin film-based devices for optical applications is accurate knowledge of the properties of substrates, on top of which the films are deposited. Lanthanum aluminate (LaAlO3 or LAO) is widely used as a substrate enabling epitaxial growth of numerous materials including such important perovskite oxides as ferroelectrics, metal-insulator-transition oxides, magnetoresistive oxides, and others. The optical properties of LAO are not well documented, especially at low temperatures. In this work, the optical properties of a 1 mm thick epitaxially polished (001)LAO substrate (MTI Corp.) were investigated by spectroscopic ellipsometry in the temperature range of 10-300 K. Spectra of the ellipsometric angles ψ and Δ were measured by a J.A.Woollam VUV-WASE ellipsometer. The optical constants were extracted using WASE software. The modeling parameters and the obtained optical constants will be presented. The refraction, extinction, and absorption coefficients will be shown in the spectral range of 0.8-8.8 eV at different temperatures of 10, 50, 100, 150, 200, 250 and 300 K. It is found that the direct bandgap is 6.1 eV at 300 K and monotonically increases to 6.7 eV on cooling to 10 K. This behavior complies with that known in many semiconductors. In contrast to the profound changes of the bandgap, the refraction coefficient from the visible spectral range is remarkably stable with temperature. The high transparency in the broad spectral range and thermal stability of refraction make the LAO substrate attractive for research and potential applications.
Authors : T. Bentrcia12,*, F. Djeffal2 and H. Ferhati2
Affiliations : 2 LEPCM, University of Batna 1, Batna 05000, Algeria. 1 LEA, Department of Electronics, University of Batna 2, Batna 05000, Algeria. * Corresponding author: E-mail: firstname.lastname@example.org.
Resume : Our objective in this work is focused on the investigation of an adaptive neuro-fuzzy inference system for predicting the ageing of Double Gate (DG) TFET devices. Such trend is expressed by assessing the degradation of some performance criteria due to the presence of interface traps. In this context, the ION to IOFF ratio, the swing factor and small signal parameters are adopted to reveal the ageing phenomenon. The employment of ATLAS 2-D simulator allows the elaboration of the dataset to be used for the training of the neuro-fuzzy system. The obtained simulation outcomes show the good performance of the developed system for predicting the ageing degradation of the considered TFET design. Moreover, the proposed approach can play an important role to investigate TFET-based nanoelectronic circuits including the ageing-related degradation effects.
Authors : Mourad Souibgui 1,*, Hosni Ajlani 1, Antonnela Cavanna 2, Ali Madouri 2, Meherzi Oueslati 1, Abdelaziz Meftah 1
Affiliations : 1 University of Tunis El Manar, Faculty of Sciences of Tunis, Unit of Research Nanomaterials and Photonic, 2092, Tunis, Tunisia 2 CNRS/C2N, Route de Nozay, F-91460, Marcoussis, France * email@example.com
Resume : Historically, Raman studies have played an important role in optical characterization of carbon allotropes and have also become a powerful tool for understanding the phonons in graphene. Different properties including strains, defects, doping and the force type between graphene-substrate could be deduced from Raman spectra and are strongly investigated theoretically and experimentally. The graphene is obtained by high-quality chemical vapor deposition (CVD) and transferred to the h-BN substrate. We focus our attention on annealing effect at 1040 C on single graphene layer (SGL) and bilayer graphene (BLG) on an h-BN substrate using Raman spectroscopy. The Raman spectroscopy study of BLG heterostructure shows that the two layers of graphene have different orientations. Before annealing, the analysis of the Raman cartography of the graphene bands, G and 2D, shows the presence of angles that depend on the spacing between the two layers of graphene. After annealing, the analysis of Raman spectra reveals the presence of uni-axial stresses induced by h-BN. Since the possibility of controlling the angle formed by the orientations of the two graphene layers, in a rotated graphene bilayer, will make it possible to produce new devices, we were interested in the way in which the angles change of value following the annealing based on the intra-layer and inter-layer processes. This makes it possible to change the structure of the graphene electronic band.
Authors : Alma Dauletbekova1*, Rakhima Balakhayeva1, Zein Baimukhanov1, Artem Kozlovskii2, Lyudmila Vlasukova3, Abdirash Akilbekov1, Sholpan Giniyatova1 and Maxim Zdorovets2,4
Affiliations : 1)Faculty of Physics and Technical Sciences, L.N. Gumilyov Eurasian National University, Nur-Sultan 010008, Kazakhstan, 2) Nur-Sultan Branch of Institute of Nuclear Physics, Nur-Sultan 010008, Kazakhstan 3)Scientific Research Laboratory of Materials and Device Structures, Belarus State University, Minsk 220064, Belarus 4)Ural Federal University, Yekaterinburg 620002, Russia
Resume : The purpose of this research is to obtain CdTe nanocrystals by electrochemical deposition in a-SiO2/Si -n track template. A conventional electrolytic cell was used for electrochemical deposition. The voltage on the electrodes was 1.5V, t = 5 min. electrochemical deposition of CdTE was carried out on two different solutions. An X-ray structural analysis showed to form cadmium telluride nanocrystals of the hexagonal phase (wurtzite) together with the amorphous phase. The use of chloride and sulphate electrolytes leads to the formation of the dominant amorphous phase of CdTe over the crystalline hexagonal phase. Subsequent annealing leads to the dominance of CdTe nanocrystals.
Authors : Šárka Havlová*†, Michal Novotný*†, Přemysl Fitl*†, Jan Remsa*, Jan Fara*†, Sergii Chertopalov*, Martin Vondráček*, Morgane Poupon*, Lenka Volfová*, Ladislav Fekete*, Valter Kiisk‡, Raivo Jaaniso‡, Martin Vrňata†
Affiliations : * Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic † University of Chemistry and Technology, Prague, Czech Republic ‡ University of Tartu, Tartu, Estonia
Resume : We present here the use of the pulsed laser annealing (PLA) method to improve (or activate) optical properties of nanostructured oxides doped with rare-earth metals. Depending on operating conditions of PLA (e.g. laser wavelength, laser fluence, number of shots, ambient pressure), a material structure changes and subsequently optical properties are affected. In this work, we prepared Eu doped Lu2O3, Y2O3 and ZnO thin films by pulsed laser deposition (PLD). They were deposited on fused silica substrates at room temperature in an oxygen atmosphere at a pressure of 1 and 2 Pa. Optical and structural properties of the films (both as-prepared and laser-annealed) were studied as well as their chemical composition and film morphology. The film morphology was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), the chemical composition was determined by x-ray photoelectron spectroscopy (XPS) and the structure was characterized using x-ray diffraction (XRD) and by XPS. UV-VIS ellipsometry, spectrophotometry and photoluminescence were used to analyze optical properties.
Authors : Hee Su Kim, Do-Hoon Hwang
Affiliations : Pusan National University
Resume : First, a thienylene-vinylene-thienylene (TVT) derivative with cyano groups in the 3- and 3'- positions was synthesized as a building block of semiconducting polymers for high mobility organic field effect transistors (OFETs). (E)-1,2-Di-(3-cyanothiophen-2-yl)ethene (2CNTVT) was copolymerized with diketopyrrolopyrrole (DPP) units via Stille coupling reaction to give 2DPP-2CNTVT and 7DPP-2CNTVT. The properties of these two polymers were compared with those of the corresponding polymers without cyano groups in TVT (2DPP-TVT and 7DPP-TVT). The effects of CN groups and branched alkyl position were found to have a significant influence on the optical, electrochemical, morphological, and charge transporting properties of the polymers. The average hole mobilities of OFETs fabricated with 2DPP-TVT and 7DPP-TVT OFETs were 1.63 and 2.2 cm2 V–1 s–1, respectively, and the average electron mobility for both 2DPP-2CNTVT and 7DPP-2CNTVT OFETs was 1.2 cm2 V–1 s–1. Second, semiconducting polymers consisting of TVT derivatives and benzo[1,2-b:4,5-b']dithiophene with conjugated thiophene side chains (BDTT) were designed and synthesized to investigate the effect of fluorine and cyano groups in the 3-position of the thiophene ring in TVT on the photovoltaic properties. The corresponding PBDTT-TVT, PBDTT-FTVT, and PBDTT-CNTVT copolymers containing TVT, di-fluoro TVT (FTVT), and di-cyano TVT (CNTVT), respectively, demonstrated considerable variations in optical, electrochemical, morphological, and charge transporting properties. PBDTT-FTVT showed suitable frontier orbital energy levels, favorable face-on orientation, and a well-mixed and smooth morphology in the blends with 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) and [6,6]-phenyl-C71-butyric acid methyl ester (PCBM). In contrast, PBDTT-CNTVT showed unfavorable frontier orbital energy levels and bimodal orientation in the thin film state, which interrupted efficient charge transport in organic photovoltaic devices. The device fabricated using PBDTT-FTVT exhibited the highest power conversion efficiency (PCE) of up to 6.50% with ITIC and a slightly lower PCE of 6.35% with PCBM.
Authors : Jong-Woon Ha, Do-Hoon Hwang*
Affiliations : Pusan National University
Resume : Our group has reported donor-acceptor type copolymers based on thieno[3,4-c]pyrrole-4,6(5H)-dione (TPD) linked with alkyl substituted-thieno[3,2-b]thiophene as π-bridge for highly efficient organic photovoltaic cells. In this work, we developed and synthesized a bi-TPD as acceptor moiety linked with alkyl substituted-thieno[3,2-b]thiophene as π-bridge to control the optical and electrical properties. Synthesized bi-TPD components with two different side alkyl chains were polymerized with benzodithiophene as donor miety to give PBDT-biTPD(BO) and PBDT-biTPD(HD). Compared to that of a polymer composed of mono-TPD, PBDT-biTPD series displayed red-shifted absorption spectra with deep highest occupied molecular energy level because bi-TPD, which consists of two TPD components and, possess longer conjugation length and stronger electron withdrawing characteristic than mono-TPD with improved solubility. The synthesized polymers were able to offer high device performance when blended with both fullerene derivative (PC71BM) and non-fullerene derivative (IT-4F). From grazing incidence X-ray scattering measurements, both neat polymer and blended films exhibited preferential face-on orientation, which is beneficial for vertical charge transport in the OPVs. Consequently, fullerene based OPV devices displayed power conversion efficiency (PCE, 8.65 and 8.99 %) for PBDT-biTPD(BO):PC71BM and PBDT-biTPD(HD):PC71BM, respectively. Comparison with the fullerene based devices, the device of PBDT-biTPD(HD):IT-4F achieved the best PCE of 9.65 % with a significantly increased short circuit current because IT-4F unit is able to more harvest absorption spectra to 800 nm compared to that of PC71BM. It is demonstrated that bi-TPD component is a promising accepting building moiety for highly efficient OPVs.
Authors : Pham Tien Hung, Vu Xuan Hien, Phung Dinh Hoat, Sangwook Lee, Byoung-Seong Jeong, Joon-Hyung Lee, Jeong-Joo Kim, Young-Woo Heo*
Affiliations : School of Materials Science and Engineering, Kyungpook National University (KNU), Daegu 41566, Korea
Resume : Tin methylammonium iodide (MASnI3) is a p-type semiconductor with excellent optical versus electrical properties. This work introduces a stable process for growing high-purity MASnI3 thin films via thermal evaporation. The growth process was proposed and discussed. The gas sensing properties of the MASnI3 thin film were investigated at room temperature with/without illumination. The film exhibited the highest selectivity toward NO2 (limit of detection: 25 ppb). Furthermore, the highest response of the film (i.e., slightly >40) toward 1000 ppb NO2 was realized after three measurement days. The gas sensing mechanism of the device was discussed and illustrated in a three-dimensional model.
Authors : Fang-I Lai, Jui-Fu Yang, Shou-Yi Kuo
Affiliations : Electrical Engineering Program C, Yuan-Ze University, 135 Yuan-Tung Road, Chung-Li, 32003, Taiwan Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Taoyuan 333, Taiwan. Department of Urology, Chang Gung Memorial Hospital, Linkou, No.5, Fuxing Street, Kwei-Shan, Taoyuan 333, Taiwan
Resume : Our dependence on fossil fuels has increased continuously since the Industrial Revolution. Currently, nearly 80% of the world’s energy comes from coal, oil, and natural gas. However, petrochemical fuels have contributed significantly to global warming because they release large amounts of carbon dioxide when burned to generate energy. This has led to extensive efforts in recent years all over the world to develop alternative energy sources in order to reduce the dependence on oil and coal. These alternative sources include biomass, geothermal and marine sources, and wind and solar energies. Among these, solar energy, a renewable form of energy that can be developed sustainably, shows the greatest promise. At present, the solar cells available can be categorised as follows: those based on (i) crystalline silicon substrates, (ii) thin films, and (iii) compound semiconductors. Despite this variety, the market is currently dominated by silicon-semiconductor-based solar cells, which have a conversion efficiency of approximately 25%. However, these solar cells can be expensive and have long production times. Further, the substrate used poses several limitations. As a result, they are impractical for use in domestic situations or in regions with harsh environments. This has led researchers to study other types of solar cells as alternatives. Dye-sensitised solar cells (DSSCs) have attracted a lot of attention because of the simplicity of their manufacturing process, low manufacturing cost, environmental friendliness, and commercial potential. The successful operation of DSSCs depends on minimising the recombination processes that occur at the injected electron/oxidised dye or electrolyte interface and ensuring efficient electron transport and subsequent electron collection. There have been several studies since 1991 on the use of TiO2 nanoparticles as photoelectrode materials in DSSCs, whose use has led to a conversion efficiency greater than 10%. The main focus has been to increase the surface area and hence the dye-adsorption capability. However, it has proven difficult to increase the efficiency further because of phenomena that occur within the grain boundaries, namely, charge trapping/detrapping events. Furthermore, the long-term stability and carrier mobility of TiO2 are also low. Some researchers have investigated the possibility of using SnO2, ZnO, or other metal oxides for producing semiconductors that can be used as photoelectrode materials, in an attempt to improve the charge-transport characteristics of DSSCs. ZnO has attracted significant attention because its wide bandgap (3.37 eV), which is similar to that of TiO2. Furthermore, its electron mobility, which is approximately 2–3 orders of magnitude higher than that of TiO2. Hence, the use of one-dimensional (1D) ZnO nanostructures (NSs) has great potential to improve the performance of DSSCs. However, the conversion efficiency of DSSCs based on these NSs is less than desirable and their photoelectric conversion efficiency also remains low. It has been reported that this is attributable to the insufficient light adsorption by the photoelectrode owing to its low surface area, and various methods have been proposed for improving the surface adsorption properties and quality of ZnO NSs. These include using the chemical solution method to fabricate the nanostructures, as this method has the advantages of being low cost, easy to control, and suitable for large-scale fabrication. Most studies on the use of ZnO NSs as photoelectrode materials in DSSCs have attempted to evaluate the dye-adsorption capabilities of various types of NSs, and very few have analysed the effects of their optical properties on DSSC performance. In this study, photoelectrodes for use in DSSCs were prepared using two types of ZnO NSs, which were fabricated using the low-temperature chemical solution method. The morphologies and optical properties of the ZnO NSs were evaluated in detail. The 2D ZnO NFs exhibited better dye adsorption properties and a higher haze value than did the 1D ZnO NRs. Simulations were performed using the FDTD method, and the results were found to be consistent with those of actual light-scattering measurements. Moreover, the results of transmittance measurements performed over a range of incidence angles indicated that the attenuation of incident light was not as pronounced in the 2D ZnO NFs, owing to which the DSSCs prepared using them exhibited higher photoelectric conversion efficiency. In addition, their light-scattering ability resulted in improved light trapping during the variable-angle I–V measurements. With the decrease in the cell efficiency with increases in the incident light angle being only 12% for the devices with the 2D ZnO NFs. Thus, DSSCs based on 2D ZnO NFs should be suitable for wide-angle applications.
Authors : Baolin Zhao ,*, Bastian Gothe , Marco Sarcletti and Marcus Halik
Affiliations : University Erlangen-Nürnberg, Organic Materials & Devices – OMD, Interdisziplinären Zentrums für Nanostrukturierte Filme, Cauerstraße 3, 91058 Erlangen, Germany e-mail: firstname.lastname@example.org
Resume : Organic molecules enable the fabrication of large-area and flexible electronics with low energy consumption . In organic field-effect transistors (FETs), the characteristics depend heavily on the thickness of the device and the charge transport at the dielectric-organic interface . To improve the devices performance, the optimization of dielectric properties and the orientation of semiconductor molecules are crucial. Herein, we present the method of self-assembled monolayers (SAMs) as functional layers in FETs, which combine dielectric and semi conductive properties in one molecular layer with full control of surface coverage and high reliability in layer formation from solution. The newly designed organic molecules with specific anchor groups and molecular design as a toolbox for p- and n-type self-assembled monolayer field-effect transistors (SAMFETs) are shown . We will demonstrate SAMFET devices based on small molecules as an integration concept, which enable the fabrication of organic complementary FETs as well as the realization of integrated circuits. The CMOS inverter using photolithography process with region selective deposition of p-/n- type SAMs in the channels, successfully operate at a low supply voltage and a high signal gain of 48. These results are expected to contribute greatly to the development of integrated circuits with high-speed operation with SAMFETs.  Wang, Sihong, et al. Nature 555 (2018) 83-88.  Yokota, Tomoyuki, et al. Nature nanotechnology 13.2 (2018): 139.  T. Schmaltz, et al. ACS Nano, 11 (2017) 8747–8757.
Authors : Hanwhuy Lim and Baek-Jin Kim (present author)
Affiliations : Hanwhuy Lim, Baek-Jin Kim; Korea Institute of Industrial Technology (KITECH), Green Chemistry Materials and Process R&D Group
Resume : Flexible and Stretchable electrodes are intensively studied because of their attraction along with the development of wearable devices, flexible displays and soft electronics. Conventional electrodes are mainly made of metal oxide or printed metal wires so that they have very low ductility and elastic deformability. To replace such rigid electrode, new materials are intensely studied such as metal nanowires, graphene, metal meshes, carbon nanofiber or conductive polymers. For the advanced electronics applications, the complex of metal nanoparticles and carbon nanotube (CNT) were developed to have both flexibility and conductivity at the same time. And we also employed the 3roll mill and planetary mixer to well dispersed hybrid of chemically modified CNT and Ag paste. Furthermore, the EA gripper including metal-CNT flexible electrode was demonstrated its feasibility and the electrostatic field generation wase verified according to the applied voltage and its mechanical behavior.
Authors : C. Guillaume(1), J.L. Frieiro(2), O. Blázquez(2), C. Labbé(1), B. Garrido(2), S. Hernández(2), C. Frilay(1), F. Lemarié(1) and X. Portier(1)
Affiliations :  Normandie Université, ENSICAEN, UNICAEN, CEA, UMR CNRS 6252, CIMAP, 6 Boulevard du Maréchal Juin, 14050 Caen, France;  MIND-IN2UB, Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franquès 1, E-08028, Barcelona, Spain.
Resume : ZnO is a well-known wide band-gap (3.3-3.4 eV) semiconductor suitable for many applications in optoelectronic industry for optical sensors and light emitting diodes (LEDs). In the present work, a white LED structure based on rare earths (RE) doped ZnO materials is considered. A complete preliminary study of the effect of post annealing treatment on the structural and optical properties of Tb-Eu doped ZnO is presented. The doped films (about 150 nm thick) were grown by radiofrequency magnetron sputtering on (100) Si substrates. They were then annealed at various temperatures (up to 1100°C) for 1h under a nitrogen flow. Transmission electron microscopy observations revealed a diffusion process of the REs toward the film/substrate interface for annealing temperatures up to 700°C. For higher temperatures, the annealing treatment led to the appearance of silicate phases (Zn2SiO4 phase) at the bottom of the film. For the extreme temperature values, new phases (RE silicates) appeared giving rise to high PL emissions from Eu suggesting an energy transfer from Tb towards Eu. An attempt to explain the origin and the evolution of the PL emissions is presented. By mixing different colors coming from the RE emissions, a white LED structure has been tempted and the first electroluminescence data on Ce, Tb and Tb-Eu doped ZnO multilayers (about 65 nm thick) annealed at 700°C are reported.
Authors : M.A. Pietrzyk1, E. Zielony2, M. Stachowicz1, A. Wierzbicka1, R. Szymon2, E. Popko2, A. Kozanecki1
Affiliations : 1 Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46 PL-02668, Warsaw, Poland; 2 Department of Quantum Technologies, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
Resume : Alloying of ZnO with CdO leads to the gradual reduction of the bandgap, which results in tuning of luminescence from UV to VIS region. Thus, ZnO/CdO heterostructures can be used of light emitting and laser diode sources operating from UV to green/blue wavelengths. The subject of investigations were ZnO/CdO multilayer that had been fabricated on a (111) Si substrate. The optical properties were analyzed by PL and the structural studies by AFM, SEM, XRD and micro-Raman spectroscopy. The micro-Raman spectra show phonon modes originating from the Si substrate and the ZnO layer. A significant broadening of the A_1^LO ZnO line with comparison to the one observed for pure ZnO layers, can indicate the formation of a ZnCdO alloy. The near resonant Raman measurements exhibit phonon modes characteristic only for the ZnO layer, namely the A_1^LO peak and its two replicas. For both excitation wavelengths the Raman spectra present a significant shift of the A_1^LO ZnO. The shift of the A_1^LO Raman line has been observed in the case of Zn1-xCdxO films. It was assigned to the inhomogeneous micro-strains. We can conclude about the existence of ZnCdO layer in the investigated samples, formed by incorporation of Cd into the crystal lattice of ZnO during the growth of ZnO/CdO multilayers. XRD measurements reveal the structure is polycrystalline with dominant orientation in the (0001) crystallographic direction. For the lower values of 2θ angles XRD signal is coming from ZnCdO and the next one from ZnO, confirming the formation of ZnCdO layer.
Authors : Young-Ju Kwon1, Joon-Sung Kwon1, Beom-Rae Noh1, Eun-Kyung Chu1, Kwang-Gyun Im1, Eung Hyuk Lee3, and Kyoung-Kook Kim1, 2*
Affiliations : 1Dept. of Advanced convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si,Gyeonggi-do 15073, Republic of Korea ; 2Dept. of Nano Optical Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea ; 3Dept. of Electronic Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea *E-mail: email@example.com
Resume : III-nitride ultraviolet (UV) emitters have an expansive application potential for polymer curing, air purification, solid-state lighting, and sterilization. However, high external quantum efficiency and low forward voltage of UV emitters are very challenging due to poor light extraction efficiency and high contact resistance. The prevailing structure for high power emitters is flip chip emitters with Al electrode which has high reflectance in UV range than Ag electrode. However, the Al electrode causes the degradation of electrode due to high contact resistance. Thus, it is essential to develop an electrode for high efficiency UV emitter that has a high reflectance and a stable ohmic contact between metal and p-AlGaN layer. In this study, we demonstrated the ITO nanograins between p-AlGaN layer and Al electrode to solve the ohmic contact problem by lowering the Schottky Barrier Height. We fabricated the various micro-hole arrays of dia. 4, 6, 8, and 10 μm with 25 μm-pitch and 75 nm depth on top of p-AlGaN layer. The 15 nm ITO layer for ITO nanograin was deposited on the patterned p-AlGaN layer. The Al electrode embedded with ITO nanoparticles has the high reflectivity of 77 % at 365 nm and low contact resistance of 7.9 ×10-4 Ω·cm2. Due to the improvement of these properties, the output power of the UV emitter was improved by 72 % compared to the UV emitter with single Al electrode.
Authors : Jeong Eun Park, Won Seok Choi, Jae Joon Jang, Donggun Lim
Affiliations : Korea National University of Transportation
Resume : The shingled module method using conductive adhesive (ECA) can be processed at a low temperature of 120 to 180°C, the efficiency is improved by reducing thermodynamic stress on c-Si. In this paper, we fabricated the c-Si cutting cells using green laser and then cell bonding was performed by using ECA for module fabrication. As experiment conditions, curing time was changed from 30 to 120 sec and curing temperature was changed from 130 to 210°C. The number of curing were changed 1-3 times and the efficiency was measured after module fabrication with various conditions. As a result, the bonding between the cutting cells did not proceed smoothly when the curing time was very short. The silver(Ag) particles, which are the main component of ECA, were not formed densely and the connection between the conductive particles was broken. As a result, the highest efficiency of 20.27% was obtained in the condition of the curing time of 60 seconds, and it was judged that a electric current path was formed due to the densely formed surface structure of the Ag particles. It was 20.27% in the primary curing times, 19.67% in the secondary curing times and 19.58% in the tertiary curing times, and showed the highest efficiency in the primary curing times. It was considered that the crack occurred due to the deterioration phenomenon in the conditions after the secondary curing times and the efficiency was gradually lowered. As a result, it was found that the highest efficiency was 20.27% at curing time of 60 seconds, curing temperature of 150°C and primary curing times. The efficiency after module fabrication increased by about 2.67% compared with the conventional cutting cell efficiency.
Authors : Ye-Bin Im1, Si-Won Kim1, Gyu-Jae Yohn1, So-Yeon Park2, Suyeon Son1, Eung Hyuk Lee3, and Kyoung-Kook Kim1,2,*
Affiliations : 1 Dept. of Advanced convergence Technology, and Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea ; 2 Dept. of Nano Optical Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea ; 3 Dept. of Electronic Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 15073, Republic of Korea *E-mail address: firstname.lastname@example.org
Resume : Because ZnO basically has n-type property due to oxygen vacancies and interstitial Zn as the point defects, it is difficult to make p-type ZnO (p-ZnO) thin films with high reliability. In addition, the capacity of the acceptor is low and the self-compensation effect is high. Nevertheless, ZnO has attractive advantages such as a large free-exciton binding energy (60 meV), relatively low costs, and direct bandgap (3.37 eV). To realize these applications such as transparent conductive electrodes (TCEs), gas sensor, and ultraviolet LEDs, stable p-ZnO growth is essential. It is necessary to understand that has a crucial effect on the structural and electrical properties for realization of the p-ZnO having excellent features and high reproducibility. The p-ZnO can be made by doping with group-V elements such as nitrogen, phosphorus, arsenic, and antimony. When a group-V element is used as a dopant for ZnO and p-ZnO can be produced because an acceptor level is formed by substitution of a group-V element in the oxygen sites. In this study, we demonstrated to grow group-V element doped ZnO using radio frequency (RF) magnetron sputtering and annealing process for a high quality p-ZnO thin film. A buffer layer was applied to decrease defects as donors. Therefore, we confirmed the electrical and optical properties of the p-ZnO thin film grown by RF sputtering. The ZnO showed the hole concentration of over 1017/cm3 after dopant activation by annealing process.
Authors : Ewa Dumiszewska1, Piotr Caban1, Piotr Knyps1, Dariusz Czołak1, Iwona Jóźwik1, Jakub Kierdaszuk2, Aneta Drabińska2, Andrzej Wysmołek2, Jarosław Gaca1, Marek Wójcik1
Affiliations : 1. Institute of Electronic Materials Technology, Wolczynska 133, 01-919, Warsaw, Poland 2, Faculty of Physics, University of Warsaw, Pasteura 5, Warsaw, Poland
Resume : Semiconductor nanowires have become very important material for optoelectronic applications. Recently, free-standing semiconductor nanowires have considerable attention in applications involving photovoltaic devices. The efficiencies of solar cells on nanowires have increased and have reached up to about 20 %. High electrical conductivity (∼104 Ω−1 cm−1), electron mobility of 15000 cm2⋅V−1⋅s−1 and high transparency (97.7% transmittance in the visible spectrum) have been recognized in monolayer graphene and predestine it for various applications, including solar cells, flexible electronics, transparent electrodes and energy storage. Here in this work we wanted to integrate graphene and nanowire technologies together. InP nanowires on epitaxial graphene on SiC substrates were grown. The growth was carried out without gold nanoparticle catalyst in a metalorganic vapour phase epitaxy (MOVPE) an AIX 200 reactor. The source gases were TMIn and PH3. The quality of nanowires was studied by means of SEM, PL and Raman Spectroscopy.
Authors : A. Radu, C. Berbecaru, S. Iftimie, V.-A. Antohe, L. Ion, S. Antohe, and D. Dragoman
Affiliations : University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125, Magurele, Ilfov, Romania
Resume : We study the behavior of electrical permittivity and mobility of ferroelectric HfO2 and HfZrO2 grown by atomic layer deposition and, respectively, of graphene/ferroelectric structures. The aim is to gain insight into phenomena at graphene/ferroelectric and ferroelectric/substrate interfaces and to extract useful information for nanoelectronic applications. The capacitance and loss tangent of ferroelectric HfO2 and HfZrO2 layers on Si/SiO2 were measured as a function of temperature and frequency. For each temperature, in heating-cooling cycles between 30 and 300oC, measurements were performed at several frequencies in the 42 Hz-5 MHz range. The heterostructures stabilize starting from the second cycle, but the capacitance and losses depend on the contact types (Au/Cr or Ag) and on the SiO2 thickness. The capacitance decreases steadily as the frequency increases, the frequency dependence of losses being more complex. At high frequencies, the capacitance is minimal at a temperature at which losses are maxima. The mobility was determined from direct Hall Effect measurements at room temperature and below for a graphene/ferroelectric layer configuration. Whether essential in nanoelectronics, mobility estimation is not straightforward. Besides Hall effect, it can be extracted from drain current-drain voltage or transconductance measurements of graphene/ferroelectric field-effect-transistor configurations. A comparison between these mobility values shows that the value extracted from transconductance significantly underestimates this parameter. ACKNOWLEDGMENTS: This work was supported by a grant of Romanian National Authority for Scientific research, CNCS-UEFISCDI, Project PN-III-P4-ID-PCCF-2016-0033.
Authors : Jae Joon Jang, Jeong Eun Park, Won Seok Choi, Donggun Lim
Affiliations : Korea National University of Transportation
Resume : The screen printing method is widely used for silicon solar cell electrode formations. However, it has a disadvantage of having high contact resistivity between wafers and electrodes. Laser-doped selective emitters (LDSE) technology can reduce contact resistivity and increases efficiency of solar cells. In this study, the selective emitter was formed to reduce contact resistivity after laser optimization experiment. We used nanosecond green laser and doped c-Si wafers with sheet resistance of 100 Ω/□ for LDSE process. The laser conditions were changed with laser power of 25 ~ 45% (2.5 W ~ 4.5 W) and laser speed of 30 ~ 60 mm/s. As a result of laser power variable experiment, the process was not performed due to low energy density under 25% or less power conditions and the process was changed from 30% or more power conditions. At 40% or more of the power, it was determined that the heat affected zone (HAZ) was gradually occurred, affecting LDSE formation. The HAZ occurs as the laser remains on the wafer for a long time, which reduces the efficiency of the solar cell. At 35% laser power, we obtained about 7 mΩ·cm2 contact resistivity and power was fixed for optimization of the LDSE process. In the laser speed variable experiment, the formation of HAZ was small and low contact resistivity about 4.8 mΩ·cm2 was obtained in the condition of laser speed of 40 mm/s. As a result, we confirmed LDSE formation and low contact resistivity in laser power of 35% and laser speed of 40 mm/s.
Authors : A.I. Popov (1), C. Balasubramanian (2), H.Klym (3), O.I. Aksimentyeva (4), E. Elsts (1), A.Moskina (1)
Affiliations : (1) Institute of Solid State Physics, University of Latvia, Latvia (2) Institute for Plasma Research, Bhat, Gandhinagar, 382 044. India (3) Lviv Polytechnic National University, 12 Bandera St., Lviv, 79646, Ukraine (4) Ivan Franko National University of Lviv, 79017 Lviv, Ukraine
Resume : Aluminium Nitride (AlN) nanostructures – nanotubes, nanowires and nanoparticles have been successfully synthesised by using a high temperature, highly non-equilibrium DC arc plasma method and investigated with different methods, including XANES, FTIR, neutron powder diffraction and inelastic neutron scattering [1-3]. Here we report the results of the cathodoluminescence studies of the AlN nanotubes and nanoparticles, which have been measured between 80 K and room temperature (RT) under electron irradition with 10 keV energy. Low-temperature CL spectra of nanostructured AlN have been compared with those of the commercially available AlN powder. The significant difference between emission spectra of the three investigated samples has been established. Commercial AlN has been found to emit a band peaked at 3.47 eV which is commonly ascribed to oxygen impurities. Emission of the AlN nanoparticles is centered around 3.66 eV while CL spectrum of AlN nanotubes show complex character with at least three peaks at 2.2, 3.0 and 3.5 eV in the photon energy range of 1.8 – 3.8 eV. CL intensity of the nanostructured samples has been found to decrease significantly at RT, most probably due to a combination of non-irradiative relaxations at the surface, electron-phonon interactions and the reabsorption of the emitted light. CL of AlN-nanotube/CsI-scintillator composites has been also studied. Energy transfer via luminescence emission from CsI scintillator to AlN nanotube is demonstrated. Luminescence properties AlN nanotube/polymer composites were also studied and compared with those obtained for AlN nanotubes and nanoparticles. References: . Balasubramanian C., et al. Journal of Physics: Condensed Matter 18 (2006): S2095. . Bellucci S., Popov A.I. et al. Radiation Measurements 42 (2007): 708-711. . Bellucci S., Balasubramanian C., Ivanov A., Popov A., Schober H. J. Neutron Research, 14(2006); 287-291.
Authors : LUU Thi Thuy Hoa(1,2) , Zixian JIA (1,2) , , Luc MUSEUR(1) 1. LPL, Laboratoire de Physique des Lasers, Université Paris 13, Sorbonne Paris Cité, 93430 Villetaneuse, France 2. LSPM-CNRS, Laboratoire des Sciences des Procédés et des Matériaux, Université Paris 13, Sorbonne Paris Cité, 93430 Villetaneuse, France
Affiliations : Mamadou TRAORE(2), Andrei KANAEV(2)
Resume : The photosensitive pHEMA-TiO2 hybrid material based on organic poly-hydroxyethyl methacrylate (pHEMA) network and titania nanoparticles, are photochrome and photorefractive bulk solids exhibiting a large electrons storage capacity [1, 2]. Their high photonic sensitivity results from an efficient separation of the photoinduced charges at the organic-inorganic interface. These materials open the potential applications of laser-induced polymerization in many fields as optics, electronics, optoelectronics, protective coatings, sensors, etc. In the present communication, we report on the synthesis of pHEMA-TiO2 hybrids by photopolymerization. The polymerization kinetics of pure 2-hydroxyethyl methacrylate (HEMA) and HEMA-TiO2 hybrid solutions under UV irradiation is monitored in situ by Raman spectroscopy. The changes of propagation and termination rate constants along the reaction are determined from the evolution of the rate of polymerization with time. The influence of UV laser intensity and photoinitiator concentration on the reaction kinetics are analyzed. The effects of TiO2 nanoparticles loading on polymerization of HEMA are also discussed. 1. P. Gorbovyi, et al., "Alkoxysilane effect in hybrid material: A comparison of pHEMA-TiO2 and pMAPTMS-TiO2 nanoparticulate hybrids," Mater. Res. Bull., 114, 130-137 (2019). 2. A. Uklein, P. Gorbovyi, M. Traore, L. Museur, and A. Kanaev, "Photo-induced refraction of nanoparticulate organic-inorganic TiO2-pHEMA hybrids," Opt. Mater. Express, 3(5), 533-545 (2013).
Authors : So Mang Park, Jeong Eun Park, Seon Wol Jeon, Eun Ji Bae, Donggun Lim
Affiliations : Korea National University of Transportation
Resume : The CdS buffer layer is has a disadvantage of causes environmental pollution. Therefore Cd-free buffer layer such as ZnS, ZnSe, Zn (Se, OH), Zn (O, OH), Sn (S, O) and Zn (O, S) is actively being developed. In this paper, the characteristics of thin films according to various complexing agents in ZnS buffer layer fabrication using solution reuse were analyzed. The ZnS thin films were deposited on the ITO substrate using EDTA, trisodium and HMTA as complexing agents. The experimental conditions varied from 0.0125 ~ 0.2 M of EDTA, 0.0125 ~ 0.1 M of trisodium and 0.0125 ~ 0.1 M of HMTA. Also, the experiment was conducted by reusing the solution up to six times through filtering. As a result, ZnS thin film was uniformly formed at all concentrations of trisodium, but the ratio of Zn ion to S ion was measured to be closest to 1:1 at 0.025 M. After trisodium was fixed at 0.025 M, solution reuse experiment was conducted. It was confirmed that the particles of ZnS thin film were uniformly deposited up to three times. EDTA confirmed the most dense and uniform film at 0.1 M. EDTA was fixed at 0.1 M and solution reuse experiment was conducted. As a result, it was confirmed that pin-holes were formed on the surface after four times of solution reuse. HMTA was uniformly grown up to 0.025 M, but the pinhole was formed on the surface from 0.05 M. HMTA was fixed at 0.025M and solution reuse experiment was conducted. As a result, it was confirmed that the particles were grown small form the experiment of solution reuse three times. However, thin films were deposited without cracks or pinholes up to six times reuse. Finally, all the complexing agents were reused up to 2 ~ 3 times, and it was confirmed that a uniform ZnS thin film was deposited.
Authors : Bonjin Koo, Yong Suk Yang, Sung Hoon Hong
Affiliations : Electronics and Telecommunications Research Institute (ETRI)
Resume : The lightweight sensory device has gained popularity in the application of correlating the effect of environmental climate on health, growth, and photosynthesis process of plants. In this study, we report a leaf-mountable strain sensor for plant growth monitoring with the sandwich configuration of Ecoflex as a biocompatible base material and CNT-Ecoflex composite as a sensing material. The strain transduction was achieved by two different structures monitoring resistance(R) and capacitance(C). With R-type strain sensors, the linearity R2=0.945 has achieved in semi-logarithmic scale with gauge factor(GF) over 50 at strain greater than 50%. Hysteresis and drift due to the nature of CNT network in viscoelastic materal were investigated in R-type. C-type strain sensors were fabricated as in-plane interdigitated electrodes shape and demonstrated the linearity of R2=0.978 in linear scale and the sensitivity(GF) of 0.4 along the lateral strain range from 0% to 100%. Hysteresis and drift performance were greatly improved since the capacitance was purely governed by geometry deformation. The fabricated sensors were integrated with RFID sensor tag device and remote data acquisition of strain signal was successfully measured.
Authors : Jae-Hyun Lee, Akpeko Gasonoo, Min-Hoi Kim, Yoonseuk Choi
Affiliations : Hanbat National University, Republic of Korea
Resume : There is a wide range of barrier requirements for flexible passivation thin films depending on the application. Alternating inorganic and organic layers are proven to be a good technique for developing multilayer passivation films for flexible applications. For instance, commercial application of multilayer passivation thin films in flexible organic light emitting displays require ultra-high barrier properties such as high resistance to water vapor and oxygen and high optical transmittance. However, their broad adoption has been impeded by delays and interruptions introduced by fabrication in multi-deposition chambers. Most of these conventional approaches are not only expensive and complex, but also require long process time and high deposition temperatures. In this presentation, we investigated poly-para-xylylene (parylene) and Aluminium Nitride (AlN) multilayer passivation thin film, fabricated within a single chamber at room temperature. A fast deposition rate was achieved for the thick parylene layer after optimizing the cracking chamber with an internal structure. We obtained the high optical transmittance of 90% and flat surface roughness of 3.16 nm (root mean square) for PEN/parylene/AlN film. The barrier properties were analyzed in terms of water vapor transmission rate using the analysis of electrical resistivity of evaporated metal thin film.
Authors : T. Leißner, Shailesh Kumar2, Martin Thomaschewski2, J. Adam, S. Chiriaev, J. Fiutowski, Sergey I. Bozhevolnyi2, H.-G. Rubahn
Affiliations : 1Center NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, DK-6400 Sønderborg, Denmark 2Center Nano Optics, Mads Clausen Institute, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
Resume : Nanotechnology requires both characterisation methods, that can look at the nanoscale and monitor processes and a scale that is typically not accessible by optical techniques, and nanofabrication methods, that can modify the local surface structure and chemistry in a well-defined manner. In this contribution, we will show recent advantages in focussed ion beam lithography (FIB) utilizing three different ion beams, namely Helium, Neon and Gallium and particularly their combination. In FIB the surface is modified through sputtering and no mask or resist is required. In contrast to electron beams at similar beam energies, ion beams travel in a much straighter fashion and allow e.g. the fabrication of high-aspect ratio structures. While relatively large structures (100 x 100 µm2) can be fabricated in reasonable time using Gallium ions, Neon and Helium ions allow very precise structuring of individual objects and polishing of structures and surfaces. We could show, that latter aspect is relevant to fabricate smooth and effective plasmonic waveguides and circuit elements.
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|09:00||Plenary Session (Main Hall)|
Nanomaterials based Photovoltaics : Jost Adam, Yogendra Mishra
Authors : Seweryn Morawiec1 and Isodiana Crupi2
Affiliations : 1 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziadzka 5, 87-100 Torun, Poland 2 Engineering Department, University of Palermo, Viale delle Scienze, Ed. 9, I-90128 Palermo, Italy
Resume : Metallic nanoparticles (NPs), sustaining localized surface plasmon resonances, are currently of great interest for enhancing light trapping in thin film solar cells. To be directly applicable in the photovoltaic industry, the NPs fabrication needs to be simple, reliable, low-cost and scalable. As such, self-assembly processes are most commonly used, and Ag is the preferred material, due to its high radiative efficiency and low imaginary permittivity. After exploring the correlation between structural and optical properties of Ag NPs fabricated by solidstate dewetting process on various substrates, we identified the fabrication conditions in which desirable NPs are obtained, but we also evidenced unexpectedly high parasitic absorption, main obstacle for photovoltaics. Thus, we introduced a novel spectroscopic method which enables the quantification of absorption enhancement and parasitic losses and demonstrated that the optical losses in the NPs are insignificant in the wavelength range of interest, while the NPs provides up to 90% useful absorption enhancement, which can be attributed to both the random front surface texture, originated from the conformal growth of the material over the NPs and to the scattering of light by the plasmonic NPs. Our optimized plasmon-enhanced thin film solar cell shows a pronounced broadband enhancement of external quantum efficiency and remarkably high short circuit current density in comparison to those reported in the literature.
Authors : E Przeździecka1, a, S. Chusnutdinow1, A. Wierzbicka1, M. Guziewicz2, S. Prucnal3, M. Stachowicz1, W. Zaleszczyk4, S. Zhou3, A. Kozanecki1
Affiliations : 1Polish Academy of Sciences, Institute of Physics, Al. Lotników 32/46, Warszawa 2Institute of Electron Technology, Al. Lotników 32/46, Warszawa 3Institute of Ion Beam Physics and Materials Research Bautzner Landstrasse 400, 01-328 Dresden, Germany 4 International Research Centre MagTop, Polish Academy of Sciences, Institute of Physics, Al. Lotników 32/46, Warszawa
Resume : The diode structure consist of ZnO:N grown by MBE on SiC (6H) n-type substrates. The turn-on voltage is at about 3.5 V under forward bias and the reverse breakdown voltage is higher than 5 V. The forward to reverse current ratios are at about 2x10^2. Forward biasing characteristics show four regions, indicating different conduction mechanism at this stages. At low voltage the slope of log(I)-log(V) plot is close to 1 - Ohmic region, at higher voltage the plot obey the relationship characteristic for recombination-tunneling, multistep-tunneling or multi-tunneling capture-emission current and next space charge limited current comes SCLC to play a role. The injection current is dominated by the injected electrons under the forward voltage and the single-carrier current forms because the barrier is higher for the holes than that for the electrons. The diffusion lengths of minority carriers, extracted from the EBIC line scan, are 130 nm for holes in n-SiC and 74 nm for electrons in p-ZnO regions. The maximum of electroluminescence EL is located at ~ 500 nm and initiated at ~-6V; the EL intensity began to increase rapidly together with the electrical current for heterojunction LEDs, indicating that the EL emission is a result of carrier transport through the p–n heterojunction. The electrical parameters was supplemented by XRD and optical analysis. Obtained results demonstrate that a high quality heterojunction between ZnO:N and SiC has been achieved.
Authors : Sebastiano Caccamo, Corrado Bongiorno, Giuseppe Fisicaro, Giovanni Mannino, Antonino La Magna, Rosaria A. Puglisi
Affiliations : CNR Institute for Microelectronics and Microsystems, Strada VIII n.5, Zona Industriale, 95121 Catania, Italy
Resume : Systems composed of organic molecules grafted on silicon nanowires promise new landscapes towards the design of materials with controlled features and functions. Possible applications span in physics, chemistry, engineering and life science. The organic molecule chosen for this experiment, the diethyl 1-propylphosphonate (DPP), presents the advantage to self-assemble by forming one monolayer onto the Si surface making this hybrid material the ideal platform to be studied by high resolution microscopy techniques. Another characteristics is that upon thermal annealing the molecule decomposes providing phosphorous atoms which diffuse inside Si where they work as dopant sources. For this reason, this approach can be used as an efficient doping method for 3-dimensional Si nano-architectures. We conformally deposit a single DPP layer over silicon nanowires and for the first time observe them by scanning Transmission Electron Microscopy at high resolution. We complement the results with numerical simulations on the molecule/silicon interaction mechanisms.
Authors : Deepak Kumar Dubey, Sudam Chavhan, Fu-Ching Tung, and Jwo-Huei Jou*
Affiliations : Deepak Kumar Dubey, Sudam Chavhan and Jwo-Huei Jou Department of Materials Science and Engineering, National Tsing-Hua University, 101 Sec2 Kuang -Fu Road, Hsinchu -30013 Taiwan Fu-Ching Tung Mechanical and Mechatronics Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan, R.O.C.
Resume : Numerous medical studies highlighted that frequent exposure to improper light, such as intensive white light or light consisting of strong blue emission considerably suppresses the secretion of melatonin (MLT) [1-4]. When such lights are rapidly utilized at night, the lack of MLT secretion disturbs the human circadian rhythm including sleep-wake behavior, cell function, and gene expression, jeopardizing human health. Moreover, circadian disruption by light-at-night markedly increases the risk of various types of cancers, including breast-, colorectal-, and prostate- cancers. The reason behind this may be a light source with high color-temperature or short wavelength light that has a remarkably high suppression effect on the secretion of the oncostatic hormone, MLT [1-4]. Amongst all the lighting sources available in the market, candles, and oil lamps are currently the friendliest lighting source to human eyes, physiology, ecosystems, artifacts, environment, and night skies due to their blue light-less emission [5-6]. Unfortunately, these hydrocarbon-burning based lighting measures suffer from several disadvantages such as energy-inefficient, fire hazard, flickering nature, greenhouse gas releasing, and hard to tune or dim. Besides, they also release fine particles of PM2.5, which leads to the risk of lung cancer, the most common type of cancer occurred all over the world [5-6]. In response to the solution for the above-mentioned issues, here, we demonstrate the design and fabrication of electric driven low color temperature candlelight style solid state lighting source based on OLED technology, which is blue hazards free, besides being energy saving and physiologically friendly. The reason why OLED technology is preferred is because of its high degree of freedom in chromaticity design, besides showing plane-light, being soft, glare-free, thin, flexible, transparent, fully dimmable, and printable, etc . Furthermore, all the OLED devices were fabricated by cost-effective solution process and thermally activated delayed fluorescence mechanism enabling exciplex forming co-host systems were used to precise confinement of charge carriers and excitons in the desired recombination zone, which are highly essential to improve device performance. The resulting 1,976 K candlelight OLED can reach a maximum brightness of 47,000 cd/m2, equivalent to 51,900 candlelight in one square meter, and its efficacy is 180 times that of the candle (~0.27±0.03 lm/W) and 3.6 times that of an incandescent bulb (~15 lm/W). Additionally, the designed light source delivers a sensationally pleasant and warm environment and attracts fewer insects after dusk. Its deep-blue light-less nature makes it less hazardous to night skies and artifacts. References:  S. M. Pauley, Med. Hypotheses, 2004, 63, 588–596.  P. R. Mills, S. C. Tomkins and L. J. Schlangen, J. Circadian Rhythms, 2007, 5, 1–9.  R. G. Stevens, G. C. Brainard, D. E. Blask, S. W. Lockley and M. E. Motta, Ca-Cancer J. Clin., 2014, 64(3), 207–218.  S. Davis, D. K. Mirick and R. G. Stevens, J. Natl. Cancer Inst., 2001, 93, 1557–1562.  J. H. Jou, Y. T. Su, S. H. Liu, Z. K He, S. Sahoo, H. H. Yu, S. Z. Chen, C. W. Wang and J. R. Lee, J. Mater. Chem. C, 2016, 4, 6070  J. H. Jou, H. H. Yu, F. C. Tung, C. H. Chiang, Z. K. He and M. K. Wei, J. Mater. Chem. C, 2017,5, 176-182  J.H. Jou, S. Sahoo, D. K. Dubey, R. A. K. Yadav, S. S. Swayamprabha and S. D. Chavhan J. Mater. Chem. C, 2018,6, 11492
Authors : Daria Miliaieva, Petra Matunova, Jan Cermak, Stepan Stehlik, Adrian Cernescu, Zdenek Remes, Pavla Stenclova, and Bohuslav Rezek.
Affiliations : Daria Miliaieva: Institute of Physics of the Czech Academy of Sciences Faculty of Electrical Engineering of the Czech Technical University in Prague; Petra Matunova: Institute of Physics of the Czech Academy of Sciences Faculty of Electrical Engineering of the Czech Technical University in Prague Walter Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4a, D-85748 Garching, Germany; Jan Cermak: Institute of Physics of the Czech Academy of Sciences; Stepan Stehlik: Institute of Physics of the Czech Academy of Sciences; Adrian Cernescu: Neaspec GmbH,Bunsenstrasse 5,82152 Planegg,Germany; Zdenek Remes: Institute of Physics of the Czech Academy of Sciences; Pavla Stenclova: Institute of Physics of the Czech Academy of Sciences; Bohuslav Rezek: Institute of Physics of the Czech Academy of Sciences Faculty of Electrical Engineering of the Czech Technical University in Prague.
Resume : Nanoscale composite of detonation nanodiamond (DND) and polypyrrole (PPy) as an organic dye is explored as a novel concept for energy generation, using nanodiamond as an inorganic electron acceptor. We present a technology for the composite layer-by-layer synthesis that is suitable for solar cell fabrication. The formation, pronounced material interaction, and photovoltaic properties of DND-PPy composites are characterized down to nanoscale by atomic force microscopy, infrared spectroscopy, Kelvin probe and electronic transport measurements. The data show that DNDs with different surface terminations (hydrogenated, oxidized, poly-functional) assemble PPy oligomers in different ways. This leads to composites with different optoelectronic properties. Tight material interaction results in significantly enhanced photovoltage and broadband (1 - 3.5 eV) optical absorption in DND/PPy composites compared to pristine materials. Combination of both oxygen and hydrogen functional groups on the nanodiamond surface appears to be the most favourable for the optoelectronic effects. Theoretical DFT calculations corroborate the experimental data. Prototype hybrid solar cell demonstrates the functionality of the concept.
Authors : F. Ehré(1), C. Dufour(1), F. Gourbilleau(1), X. Portier(1), J. Cardin(1), P. Marie(1), C. Frilay(1), B. Garrido(2), O. Blazquez(2), W. M. Jadwisienczak(3), David C. Ingram(4), C. Labbé(1)
Affiliations : (1) CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France (2)MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, Martí i Franquès 1, E 08028, Barcelona, Spain. (3)School of Electrical Engineering and Computer Science, Ohio University, Stocker Center, Athens, OH 45701, USA (4)Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA
Resume : Rare earth (RE) doped silicon host matrices have been broadly investigated to develop light emitting sources for Light Emitting Devices (LEDs). Among all REs, Cerium (Ce) has a high absorption cross section coupled with the 5d-4f transition resulting in an intense blue emission. In the past, Ce3 ions emission has been observed in SiO2 host matrix. However, such a matrix suffers from low Ce3 solubility as well as of aging effect after several current injections. On the other hand, the Si3N4 host matrix is known for its RE higher solubility and has a good electrical current injection due to its smaller band gap than its oxide counterpart. The purpose of this study is to elaborate MOS-LED structure based on Ce3 doped SiOxNy films. The SiOxNy: RE layers are deposited on silicon substrates by using RF magnetron sputtering technique under N2 reactive flow, with a typical thickness of 20-50 nm. A deep investigation is performed to obtain an intense photoluminescence signal according to the Ce and N concentrations. Up to 6 at. % of Ce3 , no saturation of the PL intensity has been observed, demonstrating the absence of Ce clusters and/or silicate phase formation thanks to the nitrogen content. The effect of the matrix composition on current injection in fabricated SiOxNy: RE MOS-LED structures will be presented and the electroluminescence (EL) properties including I-V characteristic and EL spectra will be analyzed. The influence of the nitrogen content on observed EL signal is studied through the conduction mechanisms.
Authors : Daniele Scirè, Yilong Zhou, Paul Procel, Guangtao Yang, Salvo Mirabella, Luca Spitaleri, Antonino Gulino, Olindo Isabella, Miro Zeman, Isodiana Crupi
Affiliations : Università degli Studi di Palermo, Dipartimento di Ingegneria; Delft University of Technology, Photovoltaic Materials and Devices group; Delft University of Technology, Photovoltaic Materials and Devices group; Delft University of Technology, Photovoltaic Materials and Devices group; Università degli Studi di Catania, Dipartimento di Fisica e Astronomia; Università degli Studi di Catania, Dipartimento di Scienze Chimiche; Università degli Studi di Catania, Dipartimento di Scienze Chimiche; Delft University of Technology, Photovoltaic Materials and Devices group; Delft University of Technology, Photovoltaic Materials and Devices group; Università degli Studi di Palermo, Dipartimento di Ingegneria
Resume : Silicon-based heterojunction technology (HJT) is one of the most promising candidates for high performance and low cost solar cells with world-record efficiency close to 27% in IBC architecture . The HJT exploits the excellent passivation properties of hydrogenated amorphous silicon (a-Si:H); although, the use of doped a-Si:H has drawbacks such as parasitic absorption and low-thermal budget to cope with back-end metallization. Replacing the p-type a-Si:H with molybdenum oxide (MoOx) is a viable alternative. Optimizing this hole-selective layer is needed; however information on the defect density of states (DOS), linked to oxygen vacancies  is still lacking. Layers of MoOx have been deposited by thermal evaporation and post-deposition annealed (PDA). Ellipsometry and RBS analysis confirmed the aimed thicknesses. Photodeflection spectroscopy measurements highlight a peak around 1.5 eV. We associate this phenomenon to polaron absorption . The DOS has been extracted from the deconvolution of the absorption spectra , including the polaron contribution. Results reveal a sub-band defect centered 1.1 eV below the conduction band. Albeit the intensity of such peak linearly increases with the PDA temperature, XPS analysis shows oxygen vacancies do not increase with the PDA.  K. Yoshikawa et al., Nat. Energy, 2, 2017  K. Kanai et al., Org. Electron., 11, 2010  M. B. Johansson et al., J. Phys. Chem. C, 121, 2017  M. Vaněček et al., Sol. Energy Mater., 8, 1983
Authors : L. Khomenkova, C. Labbé, C. Frilay, J. Cardin, X. Portier, F. Gourbilleau
Affiliations : CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 6 Boulevard Maréchal Juin 14050 Caen Cedex 4, France
Resume : Nowadays, silicon solar cells (Si-SCs) dominate the photovoltaic market. It is important to extend the absorption energy range of the Si-SCs and to cover completely the solar spectrum energy range. Among different solutions considered today, the use of frequency conversion layers is most attractive. In this work, we report on the effect of deposition conditions and post-deposition processing on the structural and optical properties of Er-doped Al2O3 thin films aiming at their up-conversion application. The films were grown on Si substrates kept at 300°C by thermal atomic layer deposition using Er(CpMe)3 and TMA as Er and Al precursors, respectively. The films were subsequently annealed at T=500-1000°C for 10-60 min in nitrogen flow and was studied be means of spectroscopic ellipsometry, FTIR, AFM, TEM and photoluminescence (PL) methods. It was observed that as-deposited and annealed at T<800°C films were found to be amorphous and chemically stable. Annealing at 900°C resulted in the formation of crystallite-like structure that becomes more pronounced after annealing at higher temperatures. Along with this, the formation of Er-silicate phase was observed for some samples. High-temperature annealing enhanced the PL emission from Er3+ ions and quenched PL emission related to host defects (as oxygen vacancies or their complexes). The effect of Er content on Er3+ PL emission as well as the fabrication conditions allowing the chemical composition of Er-doped Al2O3 films to be stabilized are discussed.
|15:30||Coffee / Tea Break|
New Materials and Approaches : Jost Adam, Jean-Claude Grivel
Authors : Chawki Awada*, Adil Alshoaibi, Abdullah Aljaafari
Affiliations : Physics Department, College of Science, King Faisal University, Hofuf, AL-Hasa 31982, Kingdom of Saudi Arabia.
Resume : Mesoporous Germanium (Ge) nanostructures have attracted rapidly increasing attention over the last few years. Due to its unique optical properties related to its near-infrared (NIR) and visible light emissions, mesoporous crystalline Ge opened up new opportunities for next generation optoelectronic and biomedical applications. The samples were fabricated by bipolar electrochemical etching of Ge wafer in HF-based electrolytes. In our previous work, high resolution scanning transmission electron microscopy (HRSTEM) provided strong evidence that NIR originates from the size reduction of the nanocrystallites. However, there are still many questions to be revealed concerning the size-related emission of the nanocrystallites. In this work, we will show some results obtained by Raman spectroscopy. This one is a very sensitive technique that allows studying the physical properties of nanostructures. Among these properties, we will focus on the study of the size effects of the nanocrystallites of Ge and their distribution on the phonon modes, a new phonon-confinement model was developed to extract the size of the core and the crystallites for different etched times. The results were compared with the atomic force microscopy and Scanning transmission electron microscopy measurements.
Authors : Lei Zhu, John Buckeridge, Alexey A. Sokol, Richard A. Catlow
Affiliations : Department of Chemistry, University College London (UCL)
Resume : Group-III (Al, In & Ga) nitrides and their doped alloys are engineered into various energy profiles and super-lattices for optimizing material’s performance and improving efficiencies. Our work is based on QM/MM methodologies (developed at Daresbury in collaboration with UCL) to model the electronic structures of native defects and impurity centres in III-nitride materials and their interfaces. At this stage, two-body interatomic potentials are used and intrinsic point defect energies of AlN, as well as Schottky and Frenkel defect energies, are calculated for the system. Our results agree well with earlier work, upon which we will build by applying DFT and quantum mechanics calculations for further modelling on the system. This work is extended to study the properties of elementary defects and their complexes in solid solutions of these nitrides and their interfaces with a view of gaining insights into the work of relevant optoelectronic devices.
Authors : Stanislav Cichoň, Jarmila Balogová, Michal Rameš, Radek Ješko, Jan Vlček, Ján Lančok, Joris More-Chevalier
Affiliations : Institute of Physics of the Czech Academy of Sciences Na Slovance 1999/2 Prague 18221 Czechia
Resume : Rh-Mn-Sb and Ir-Mn-Sb ternary systems are expected to present half-metallic magnetic Heusler alloys attractive for spintronics and magnetoelectronics. So far, there have been limited experimental investigations in these systems. In this study, Rh2MnSb, Mn2RhSb and their Ir analogues were prepared as epitaxial thin films by sputtering and their growth, structure, morphology and magnetic properties were investigated and compared employing a wide range of complementary characterization techniques. The films were prepared on MgO(001) substrates at temperatures up to 750°C in an Ar plasma at 2 Pa in an UHV chamber with two types of thickness; 20 nm and 500 nm. In terms of resulting structure, morphology and properties, they manifested a remarkably tight relation to growth temperature. Up to 400°C, prepared samples of all types of compositions displayed a nanocrystalline multiphase structure with indistinct morphology. On the other hand, above 400°C every temperature increase by 100°C resulted in formation of a particular material. Also, it seems that the Sb melting temperature, 630.5°C, represented an important threshold with regard to the growth temperature. Rh2MnSb and Ir2MnSb showed well defined ferromagnetic behavior with Curie temperatures spanning between 300 and 350 K. In the Mn2RhSb and Mn2IrSb case, their magnetic character was more complex and deserves further attention and investigation.
Authors : Stefan Tappertzhofen, S. Bette
Affiliations : aixACCT Systems GmbH, Aachen, Germany
Resume : Research on novel lead-free pyroelectric thin films is triggered by their promising integrability in CMOS processes and application in environmental friendly infra-red sensors. High precision characterization of such materials is a key challenge in development of new pyroelectric materials. In this study, we report on the characterization of pyroelectric thin films and piezo-composites, in particular the analysis of the pyroelectric response and micro- and nanoscale thermal analysis, by using an advanced laser-based stimulation technique. We identified wide band gap semiconductor thin films fabricated by PVD and CSD processes, including Aluminum nitride and Scandium doped Aluminum nitride, as model materials for pyroelectric sensors due to their excellent dielectric properties and CMOS compatibility. We will report on the physical origin of the pyroelectricity in AlScN. By high frequency stimulation of a quantum cascade infrared-laser we measured with high spatial resolution through thickness polarization of integrated samples similar to the Laser Intensity Modulation Method. These results are complemented by thermal simulation for fundamental thermal analysis down to the nanoscale. Our novel laser-based measurement system is an essential step forward for precise material characterization in research, and quality control on industrial scales for optimized device reliability.
Authors : E. Trifonofa, S. Marenkin, A. Ril, I. Fedorchenko, O. Rabinovich, S. Didenko
Affiliations : Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Science NUST MISIS
Resume : Components that form an eutectic composition and have low inter solubility are more preferred for a magneto-granular structure in semiconductor-ferromagnet systems. In that case simultaneous components crystallization of an eutectic melt during the cooling takes place. This leads to the specific fine-dispersed structure creation. The ultra-high alloy supersaturation leads to a significant supercooling of all phases, and causes metastable crystallization. These factors leads to a synergistic effect, contributing to nanostructuring for granular structure creation. In this work the interaction in the CdAs2 ? MnAs system is investigated. CdAs2 is a semiconductor with a band gap 0.9 eV (1.14 eV at 0 K), and has considerable anisotropic of optical and electric properties. It is crystallized in the tetragonal structure (space group I4122) with the unit cell parameters: a=7.954 Å, c=4.678 Å. In order to choose optimal compositions and synthesis parameters for grained structures, we have studied phase equilibrium in the CdAs2 ? MnAs system using a set of physicochemical methods. CdAs2?MnAs system was investigated by X-ray powder diffraction (XRD), differential thermal analysis (DTA), optical and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) of the samples was carried out in a Q20 system (TA Instruments) at heating and cooling rates from 6 to 18 °/min in temperature interval 0-100 °C. The DSC curves showed the structural transformation effect from hexagonal to orthorhombic modification of the ??? MnAs. The curve clearly shows the reversible thermal effect. CdAs2?MnAs system phase diagram was investigated by DTA, X-ray and SEMThe eutectic coordinates are 94 mol.% CdAs2 and 6 mol.% MnAs, with Tmelt=614 °C. This work received financial support from the Ministry of Education and Science of the Russian Federation (Subsidy Grant Agreement no. 075-02-2018-210 dated November 26, 2018, unique identifier of the agreement RFMEFI57818X0266).
Authors : J. S. Cabaço, J. P. Araújo, E. Alves, S.Magalhães
Affiliations : IFIMUP, Departamento de Física e Astronomia da Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal; IPFN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal;
Resume : The ability to have a tunable band-gap that extends part of the ultraviolet (UV) region makes group-III nitrides, and in particular Al_(1-x) Ga_x N, suitable for many applications. Some of which are the production of blue LEDS and lasers, as well as high-electron mobility transistors. The resistance to radiation is of utmost importance in the semiconductor industry. In this work we explored the channeled along the c-axis implantation of Argon, an inert element, in ~500 nm thick films of AlGaN grown on c-Al2O3 substrates. By increasing the energies of implantation the strain of the implanted volume, suggested as being the driving force for crystallographic defects, can be evaluated as function of depth using high resolution X-ray diffraction (XRD). Calling upon computer simulations based on the dynamical theory, combined (0002), (0004) and (0006) 2theta-omega radial symmetrical reflections show that increasing implantation energy results in increased lattice-parameters in the implanted region. The thicker strained regions arising from higher energies of implantation are, therefore, followed by higher density of defects. Comparison between channeled and random implantation directions is also discussed in terms of accumulated strain and crystal damage .
Authors : Wlodzimierz Kutner,1,2; Katarzyna Bartold,1; Agnieszka Pietrzyk-Le,1; Karolina Golebiewska,1; Wojciech Lisowski,1; Tan-Phat Huynh,1,4; Zofia Iskierko,1; Marta Sosnowska,1,4; Krzysztof Noworyta,1; Silvia Cauteruccio,3; Emanuela Licandro,3; and Francis D’Souza4
Affiliations : 1Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland; 2Faculty of Mathematics and Natural Sciences, School of Sciences, Cardinal Stefan Wyszynski University in Warsaw, Wóycickiego 1/3, 01-938 Warsaw, Poland; 3Department of Chemistry, University of Milan, Via Golgi 19, I-20133 Milan, Italy; 4Department of Chemistry, University of North Texas, 1155 Union Circle, No. 305070, Denton, Texas 76203-5017, United States.
Resume : By molecular imprinting in polymers, we prepared chemical sensorsfor selective determination of genetically significant oligonucleotides. These included 5’ TATAAA 3’ (T thymine and A – adenine)  and 5’ GCGGCGGC 3’ (G-guanine, C-cytosine)  hexa- and octanucleotide, respectively. For that, by electrochemical polymerization we synthesized and simultaneously deposited on electrodes molecularly imprinted polymer (MIP) films rich in sequence-defined hexakis- and octakis(2,2’-bithien-5-yl) hybridizing probes. With the density functional theory (DFT) modeling, synthetic procedures developed, and isothermal titration calorimetry (ITC) quantifying, the A-, C-, G- or T-substituted 2,2’-bithien-5-yl functional monomers capable of Watson-Crick pairing with the template consisting of the target oligonucleotide or its peptide nucleic acid (PNA) analog of pre-programmed nucleobase sequences were designed. For transduction of oligonucleotide recognition into a useful analytical signal, we applied piezoelectric microgravimetry (PM), capacitive impedimetry (CI), and surface plasmon resonance (SPR) spectroscopy under either stagnant-solution or flow-injection analysis (FIA) conditions. The hexakis- and octakisnucleotide chemosensors discriminated one- and two-nucleotide-mismatched oligonucleotides, respectively at room temperature. Using EIS, we determined the target oligonucleotide with the 200 pM limit of detection. With the EIS determined apparent impact factor of ca. 4.0, the octakis chemosensor discriminated 5’ GCGGCGGC 3’ from Dulbecco’s modified Eagle’s medium interferences. 1. Bartold, K., et al., ACS Appl. Mater. Interfaces 2017, 9, 3948. 2. Bartold, K., et al., ACS Appl. Mater. Interfaces 2018, 10, 27562.
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Carbon Nanomaterials (1D-3D) : Yogendra Mishra, Jean-Claude Grivel
Authors : Magdalena Birowska, Jens Kunstmann
Affiliations : University of Warsaw, Faculty of Physics, Pasteura 5, 02-093 Warsaw, Poland; Department of Chemistry and Food Chemistry TU Dresden, 01062 Dresden, German
Resume : Atomically thin, magnetic materials have recently gained a lot of attention in the field of two-dimensional (2D) materials . Single magnetic layers with critical temperature above room-temperature are extremely attractive for fundamental studies and could potentially be the basis for a new class of information storage. Probing the magnetic order of the 2D systems by conventional experimental means is very challenging. However, it is well known, that even in the single layer limit, semiconducting two-dimensional materials strongly absorb light. Therefore, optical spectroscopy is a good method for their characterization. In order to shed light on the intriguing phenomena of 2D magnetism, we present theoretical investigations of the optical properties of the layered material MnPS3, which is one important example from the large family of transition metal phosphorus trisulfide (MPS3). Our study reveals, that the interband absorption spectrum, which is proportional to the imaginary part of the dielectric function, is very similar for different possible magnetic order of MnPS3. On the other hand, the calculated effective masses of electrons and holes do depend on the magnetic order, which is reflected in the binding energy of excitons in the studied systems. In addition, our studies reveal that the Hubbard correction (U) in the DFT U approach can have a crucial impact on the prediction of the optical and electronic properties of the investigated structures. MB is funded by the NCN grant no. UMO-2016/23/D/ST3/03446.  M. Gibertini et al., Nat.Nanot. vol. 14, p. 408 (2019).  M. Evain et al., J. of Solid State Chem. vol. 7, p. 244 (1987).
Authors : Weifang Lu1*, Nanami Goto1, Naoki Sone1,3, Kazuyoshi Iida1,4, Atsushi Suzuki1, Hedeki Murakami1, Mizuki Terazawa1, Masaki Ohya1,4, Motoaki Iwaya1, Tetsuya Tekeuchi1, Satoshi Kamiyama1, and Isamu Akasaki 1,2
Affiliations : 1Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku-ku, Nagoya, 468-8502, Japan 2Akasaki Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 460-8601, Japan 3Koito Manufacturing CO., LTD. 4 Toyoda Gosei CO., LTD.
Resume : GaN based nanowires has been intensively investigated for their promising potential in high-efficiency lightning technologies. As the advantages of being dislocation and strain-free, zero quantum-confined stark effect on m-planes, and improved light extraction efficiency, core-shell InGaN/GaN multi-quantum well (MQS) have been demonstrated on GaN nanowires for LEDs and laser applications . Nevertheless, the point defects incorporated in GaN core can migrate and further be incorporated into InGaN/GaN quantum-wells . Here, we report the luminescent properties of core-shell structures of InGaN/GaN MQS grown on GaN-based nanowires with AlGaN undershell. The GaN core nanowires growth was performed by using continuous-flow mode in metal organic chemical vapor deposition (MOCVD). An AlGaN shell was coaxially grown on the GaN nanowires by MOCVD, followed by five pairs of InGaN/GaN quantum shells. For comparison, samples without and with low In incorporation (3%) of InGaN undershell were prepared with the same growth conditions, respectively. Cathodoluminescence (CL) was used to probe the emission at different penetration depths and positions of the nanowires to assess the luminescent properties. The photoluminescence (PL) spectra of the nanowires show an obvious degradation of the defect-related yellowish emission by using AlGaN undershells. The CL maps evidence a significant improvement of the emission intensity along the nanowire, which is ascribed to the reduction of point defects incorporation into the InGaN/GaN MQS structures. This comprehensive investigation has shown that the coaxial InGaN/GaN MQS with AlGaN undershell grown on GaN nanowires can provide a promising approach for realizing highly efficient nanowire-based optoelectronic devices.
Authors : Ewelina Rozbiegała (1,2), Sebastian Zlotnik (1), Karolina Piętak (1,3) and Mariusz Rudziński (1)
Affiliations : (1) Łukasiewicz Research Network - Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland; (2) Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw; (3) Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw;
Resume : Graphene transferred onto spatial, three-dimensional (3D) structures is a new approach for improving the efficiency of optoelectronic and photovoltaic devices. Spatial structure enlarges active surface for optical or chemical phenomena relative to bulk, conventional substrates. Furthermore, such spatial structures also enable graphene’s modification from both sides. We investigated the novel three-dimensional AlGaN-based microcolumns as a substrate for transferred graphene. These spatial structures are analogous to the nanowires, however they are stable and stiff, with controllable shape, length and distance between them. This features eliminate the high rate of defect observed in graphene deposited on inhomogeneous nanowires . For these reasons, it is possible to avoid such high level of graphene degradation. Moreover, allows to determine graphene’s behaviour, such as strain presence, and quality characteristics in two cases, i.e. when graphene is free-standing layer on the microcolumn surfaces and when is freely suspended between them. In this work, graphene was grown by chemical vapor deposition (CVD) and transferred onto 3D AlGaN-based microcolumns which in turn were grown by metalorganic vapor phase epitaxy (MOVPE). Quality of graphene was revealed by Raman spectroscopy and electron microscopy (SEM) observations. Hall measurements were investigated in order to evaluate the electrical properties. Raman spectroscopy showed close dependence between distance and tips (conical or flat) type of microcolumns and properties of graphene.  Kierdaszuk et al., Carbon N. Y. 128 (2018). Acknowledgments: This work was supported by National Science Centre (NCN) within the OPUS10 2015/19/B/ST7/02163 project.
Authors : Jaeyoung Lim, Dongmok Whang
Affiliations : SAINT Sungkyunkwan University
Resume : Twisted bi-layer graphene(tBG) is different physical properties depending on the twisting angle, therefore accurate angle control and clean interlayer are essential to fabricate tBG. Generally, methods of fabricating tBG is by stacking two exfoliation graphene flakes from HOPG. Although using CVD synthetic tBG is effective to research and develop devices of tBG, it is very difficult to directly synthesize tBG of desired twist angle. When fabricating tBG by transferring two CVD synthetic single layer graphene, the polymer support layer used in the transfer process is trapped and interferes with interlayer interaction. We report the direct transfer of CVD synthesized graphene from catalysts for twisted bi- and multi-layer graphene with accurate twist angle and clean interlayer. As a result of our previous research, graphene synthesized on hydrogen-terminated germanium is the single crystal and extremely weak adhesion between graphene and underlying substrate. So we can easily pick up graphene from the catalyst by placing materials, which have moderate adhesion with graphene on graphene. The van der Waals interactions between 2D materials such as graphene and graphene or hBN and graphene are sufficient adhesion to pick up graphene from the catalytic substrate. Thus, we were able to fabricate twisted bi-layer graphene with varying twist angles by placing graphene at a controlled angle onto synthesized graphene. In addition, through repeated pick and place, we can fabricate the twisted multi-layer graphene. Moreover, through pick and place using hBN instead of graphene, we easily fabricated van der Waals heterostructure of hBN encapsulated graphene. This approach can be a suitable method for fabricating controlled twist angle van der Waals heterostructures.
Authors : Choon-Gi Choi1,2
Affiliations : 1Graphene Research Lab. Electronics and Telecommunications Research Institute (ETRI), Daejeon, Korea 2School of ETRI (ICT-Advanced Device Technology), University of Science and Technology (UST), Daejeon, Korea Email address of presenting author: email@example.com
Resume : Wearable and flexible pressure-strain sensors that are attachable on human skins or body has extended their applications of conventional pressure sensors to a much wider range such as monitoring of physiological signals, electronic skin, human–machine interactions, artificial limb implants. To be applicable in such broader spectrum, a wearable strain-pressure sensor should be able to accurately detect subtle body signals from external stimuli in an extensive sensing range from pulse signals to knee joint bending. Furthermore, they must exhibit high reliability and reproducibility after repeated mechanical strain. Herein, flexible and wearable pressure-strain sensors for human motion detection are introduced. Two sensors are based on graphene composites such as rGO (Reduced Graphene Oxide)-SWCNT composite coated fabrics and MoS2/Graphene foam/Ecoflex hybrid nanostructures. Sensing performance and reliability at different points such as fingertip, finger joint and wrist for electronic gloves are presented. Sleepiness prevention test at eye rims and nape is also presented. The fabricated sensors showed potential in practical applications such as a human motion sensor to detect drowsiness and an array type tactile sensor. These sensors can be applicable for personalized physiological monitoring, prosthetic hand and leg, car securities, smart shoes and chairs, etc. In addition, a multifunctional EMI shielding skin with excellent EMI shielding effectiveness (SE) and pressure sensing performance are also introduced.
Authors : Azmira Jannat, Jian Zhen Ou
Affiliations : School of Engineering, RMIT University, Melbourne, Australia
Resume : Two dimensional (2D) post-transition metal chalcogenides is an emerging group of promising materials for high-performance electronic and optoelectronic devices [1-2]. However, the synthesis of this group of 2D materials with a lateral dimension of > 50 µm has been a challenge [3-4]. In this work, we present a simple way to synthesis 2D indium sulfide (In2S3) from sulfurization of the surface oxide layer of melted indium metal. 2D In2S3 is determined to feature p-type semiconducting behavior with a direct bandgap of ∼2.9 eV, potentially offering the broad detection range from UV to visible blue light region. The 2D In2S3 based photodetector exhibits a very high photoresponsivity of 8364.4 AW-1 with an excellent external quantum efficiency of 3.7067×104% and a detectivity of 4.4205 × 1010 Jones. The synthesis technique is facile, scalable, and holds promise for creating atomically thin semiconductors at wafer scale. Furthermore, the impressive optoelectronic properties of 2D In2S3 represent it as a suitable candidate for future generation optical and electronic devices.
Authors : Jianbo Sun, Maurizio Passacantando, Luca Camilli
Affiliations : Department of Physics, Technical University of Denmark; Department of Physical and Chemical Sciences, University of L'Aquila; Department of Physics, Technical University of Denmark.
Resume : The physical properties of two-dimensional (2D) materials depend strongly on the number of layers , . Hence, methods for controlling their thickness with atomic layer precision are highly desirable, yet still too rare, and demonstrated for only a limited number of 2D materials . Here we present a simple and scalable method for the continuous layer-by-layer thinning that works for a large class of 2D materials, notably the germanium-based 2D materials. It is based on a simple oxidation/reduction process, which selectively occurs on the topmost layer. Through a combination of atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction experiments, we demonstrate this layer-by-layer thinning method on germanium arsenide (GeAs), germanium sulfide (GeS) and germanium disulfide (GeS2). Our strategy, which we believe could be applied to other classes of 2D materials upon proper choice of the oxidation/reduction reagent, could pave the way for the realization of 2D material-based devices, such as electronic or opto-electronic ones, where a precise control over the number of layers (hence over the material’s physical properties) is needed.  S. Z. Butler et al., ACS Nano, vol. 7, no. 4, pp. 2898–2926, 2013.  X.-L. Li et al., Adv. Funct. Mater., vol. 27, no. 19, p. 1604468, 2017.  Y. Liu et al., ACS Nano, vol. 7, no. 5, pp. 4202–4209, 2013.
Authors : M. Stachowicz1, J. M. Sajkowski1, A. Pieniazek1, S. Kryvyi1, M. Kozubal2, A. Kozanecki1
Affiliations : 1Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46 PL-02-668 Warsaw, Poland; 2Institute of Electron Technology, Al. Lotników 32/46 PL-02-668 Warsaw, Poland
Resume : Two types of photonic structures grown by MBE on c-ZnO substrates were studied. The first one is composed of 5 pairs of ZnO/ZnMgO layers (60/50 nm), the central ZnO microcavity (300 nm) and 5 bilayers on top. The second one is a superlattice (SL) structure composed of 80 pairs of thin ZnO/ZnMgO layers (1.5/1 nm). Layer thicknesses were checked using cross-sectional Scanning Electron Microscope (SEM) mapping. The Mg contents in the ZnMgO layers has been determined to ~40% in the SL using Rutherford backscattering spectrometry and numerical simulations of the spectra. The Mg contents in the thick photonic structure were ~15%. High-Resolution X-ray Diffractions measurements revealed that both studied structures are wurtzite without precipitates of foreign phases. Their crystallographic quality is perfect as satellite lines up to the 8th order confirmed the existence of highly periodic superlattices. Reciprocal space mapping allowed to calculate the lattice constants and revealed that the structures are strained, however, partial relaxation has been found in the case of the SL with high Mg contents. The observed spatial distribution of the emission in low-temperature SEM-CL maps revealed transient regions between the substrate and strained ZnMgO/ZnO structures of quenched emission due to generation of misfit defects. Acknowledgements. The work was supported by the NCN project DEC-2018/28/C/ST3/00285 and also DEC-2014/15/B/ST3/04105
Carbon Nanomaterials (1D-3D) : Jost Adam, Rosaria Puglisi
Authors : Dawid Janas
Affiliations : Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 4, 44-100 Gliwice, Poland
Resume : Due to their unique electrical, thermal, mechanical, optical and other properties, carbon nanotubes have attracted attention of scientists from every part of the world. For instance, the ability to conduct thermal or electrical energy in a significantly more efficient way than copper made us believe that we have finally created materials able to follow the rapid pace of the development of the civilization. Silicon and other classical materials operate close to their theoretical limits, therefore their successors have to step in shortly for us to continue the technological progress. Unfortunately, the promising performance of individual carbon nanotubes has been found to be not easily scalable and their macroscopic networks present inferior properties. One of the key underlying reasons is that these ensembles are formed from a plethora of carbon nanotubes of different types. To tackle this problem, these carbon nanotube blends have to be sorted first into highly-defined fractions. Recently, a range of sorting methods have been developed for this purpose, but most of them either require expensive infrastructure or they have a very tedious and iterative nature . Herein, we would like to present our results how this can be achieved in a much more convenient way that is based on a single step aqueous two-phase extraction method [2,3]. To demonstrate the application potential of these sorted materials, we will also show how to make thin free-standing films from them based on any type of nanocarbon [4,5].  D. Janas, Towards monochiral carbon nanotubes: a review of progress in the sorting of single-walled carbon nanotubes, Materials Chemistry Frontiers 2 (2018) 36-63.  E. Turek, T. Shiraki, T. Shiraishi, T. Shiga, T. Fujigaya, D. Janas, Single-step isolation of carbon nanotubes with narrow-band light emission characteristics, Scientific Reports 9 (2019) 535.  E. Turek, B. Kumanek, S. Boncel, D. Janas, Manufacture of networks from large diameter single-walled carbon nanotubes of particular electrical character, Nanomaterials 9 (2019) 614.  D. Janas, M. Rdest, K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Materials & Design 121 (2017) 119-125.  D. Janas, G. Stando, Unexpectedly strong hydrophilic character of free-standing thin films from carbon nanotubes, Scientific Reports 7 (2017) 12274.
Authors : Chungwon Lee, Jun min Suh, Ho Won Jang
Affiliations : Seoul National University
Resume : In recent days, taste sensing have been an important issue in terms of, detecting food quality or sensing various chemical substances from specific materials. This kind of taste sensor mainly uses 2-Dimensional materials such as graphene for sensing rather using lipids or other biological substances. The aim of using 2D materials rather lipids is for longer use; bio-substance based taste sensors have very high selectivity and sensitivity but the life span of the device is short and it is sensitive to external atmosphere. For long term use and daily usage, 2D material based sensors have the advantage to bio-based sensors. Here in, we report graphene based taste sensors graphene decorated with gold for glucose sensing and nafion spin coating on graphene for pH sensing. Graphene is the main source of sensing and the decorated materials help to enhance selectivity by absorbing or penetrating the target material. Gold is well known to have selectivity to glucose and nafion has the ability to selectively penetrate cations. Gold is decorated with e-beam deposition; which thickness is about 2nm. On the other hand, nafion is spin coated onto a graphene transferred substrate.
Authors : Siva Reddy Assaf Ya'akobovitz
Affiliations : Faculty of Engineering Sciences Ben-Gurion University of the Negev, Israel
Resume : Three-dimensional (3D) graphene is a porous structure comprised of multilayers of graphene. In this work, we study the feasibility of chemical vapor deposition grown 3D graphene to operate as a resonating nanoelectronic device. The electrostatic operation of 3D graphene is first demonstrated under steady electrostatic field, followed by its dynamic excitation. Our analysis show that electrostatic operation of 3D graphene results in highly compliant mechanical behavior due to sliding of the graphene layers under the influence of the electrostatic field. We also found that the electrostatic dynamic excitation of the 3D graphene yields wide bandwidth frequency response due to significant energy dissipation. As a results, 3D graphene is highly attractive material for high-end nanoelectronics applications, such as resonating sensors (e.g., accelerometers and force sensors), electronic components (e.g., electromechanical band pass filters), micro/nano-electromechanical (MEMS/NEMS) resonators, and more.
Nanodevices and Sensors : Yogendra Mishra, Rosaria Puglisi
Authors : Yulia Spivak
Affiliations : Saint-Petersburg Electrotechnical University “LETI”
Resume : In this talk, we will review the composites based on porous silicon functionalized with Ag or Ni with a variety of morphology of the guest phase (0D-3D) obtained by electrochemical methods and its applications in sensors, optoelectronics and biomedicine. Some features and problems of detecting and characterizing a guest phase in a porous matrix will be highlighted, as well as the ways to solve it. The possibilities of design the morphology of metal clusters on the por-Si surface by controlling the properties of it (morphology, porosity and wettability) are shown using Ag as a guest material. Silver clusters of various dimensions were obtained depending on the characteristics of por-Si: 0D - spherical, triangular clusters, 1D - filled by metal pore channels, 2D - layers, 3D - dendrites, and also fractal aggregates). Our findings showed that the composition of adsorption centers on the por-Si surface (adsorption centers exhibiting the properties of an acid or a base of Lewis or Brønsted) strongly depends on the technological conditions and may significantly affect on the nature of the interaction with the “guest” substance. A proposed technological approach allows obtaining a composite material “Ag-por-Si” with a designed morphology of silver clusters in one cycle of electrochemical processing of single-crystal Si. The influence of the synthesis conditions of introducing Ni into por-Si on electrical properties of "Ni-por-Si" composite and its changes under special gas atmosphere by impedance spectroscopy is discussed.
Authors : Yonatan Calahorra1, Anke Husmann1, Alice Bourdelain2, Wonjong Kim3, Jelena Vukajlovic-Plestina3, Chess Boughey1, Qingshen Jing1, Anna Fontcuberta i Morral3, Sohini Kar-Narayan2
Affiliations : 1 Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UNITED KINGDOM 2 Ecole Centrale de Lyon, Ecully, Rhône-Alpes , FRANCE 3 Ecole Polytechnique Federale de Lausanne, Institut des Materiaux, BM 2138 (Batiment BM), Station 17, CH-1015 Lausanne, Lausanne, SWITZERLAND
Resume : The combination of semiconducting and piezoelectric properties in materials e.g. ZnO, III-Ns and other III-Vs, has given rise to unique physical phenomena such as controlling the characteristics of a semiconductor device with applied stress. This was coined as the piezotronic effect. Piezotronic sensors exhibit strain gauge factors orders of magnitude larger than piezoresistive sensors. Here we demonstrate an extremely high piezotronic sensing capability of GaAs NW ensemble Schottky diodes. The measured piezotronic sensitivity of our device, i.e. the Schottky barrier height change with pressure, was about 7800 meV/MPa. This is an order magnitude higher than record numbers obtained with optimized structures of ZnO – a material 10 times more piezoelectric than GaAs. We explore the underlying device physics and explain the high sensitivity. We identify three main contributors, related to the nanoscale characteristics and growth method of the NWs: i) pressure focusing – the nanowire ensemble geometry results in pressure applied to the top electrode to be focused/enhanced in the nanowires, thus increasing the actual stress acting on them; ii) the nanowires are mostly depleted, a result of geometry and nominally undoped growth. This means that the entire length of the NW becomes piezo-active and susceptible to exhibit the piezotronic effect; iii) our analysis suggests that current is flowing primarily through the top facet of the nanowires, which is piezo-active, and therefore no competing current routes which are not-piezo-active are holding back performance. We believe that these analysis and results will serve as future guidelines for designing superior pressure sensors through established semiconductor technology.
Authors : Merve OZPIRIN, Ozgenc EBIL
Affiliations : Department of Chemical Engineering, Izmir Institute of Technology
Resume : Functional polymeric coatings have recently attracted much attention for sensor applications due to their tunable chemical and physical properties, and their ability to be deposited on low-cost substrates. Conventional wet process that involves solvents films suffer from wetting and material compatibility issues, limitation of solid flat substrates. As a subset of Chemical Vapor Deposition (CVD) methods, initiated-CVD (iCVD) overcomes many of these limitations, enable the use of any materials with complex geometries as substrates with a fine control of film properties during deposition. In this study we investigate the applicability of polymer film functionalization by binding of selected fluorescent nanoparticles using various pre- and post-polymerization methods that are compatible with iCVD technique for biological and chemical sensing applications. Here, we present fabrication of copolymer coatings via iCVD using poly(glycidyl methacrylate) (pGMA) as the main functional polymer which was selected due to epoxy group in its structure. Functionalization is achieved via epoxy ring opening reactions which can be done pre- and post-polymerization to incorporate fluorescent nanoparticles including various dyes and quantum dots (CdSe, CdTe etc.) to either monomers or polymers. By detailed structural and optical characterization of fabricated functional polymer films, the feasibility and effectiveness of various pre-and post-polymerization functionalization methods are reported.
Authors : Kunmo Chu, Yoonchul Sohn, Jai Kwang Shin
Affiliations : Samsung Advanced Institute of Technology; Chosun University; Samsung Advanced Institute of Technology
Resume : Human skin allows us to perceive various shapes and textures, changes in temperature, and varying degrees of contact pressure. An artificial skin with such sensory capabilities is often referred to as sensitive skin, smart skin, or electronic skin (e-skin). Significant progress in the development and advancement of e-skin has been achieved in recent years, in which particular emphasis has been placed on mimicking the mechanically compliant yet highly sensitive properties of human skin. Important considerations for the development of e-skin are the choice of materials used in its fabrication and the ability to confer the mechanical properties of human skin (low modulus, stretchability and flexibility) into its artificial counterpart. Recently developed nano-materials have been tried to apply for the fabrication of the devices mimicking E-skin. Among those are carbon nanotube, graphene, and organic based materials such as conducting small molecules and conductive polymers. While naturally occurring human skin has the ability to repair itself after incurring mechanical damage, this property has yet to be fully realized in e-skin. For artificial skin, the ability to repair both mechanical and electrical damage would be highly advantageous for practical applications. In this study, highly conductive and reversible conductor structure is formulated by combining Ga-based liquid metal, especially the eutectic alloy (EGaIn: 75 wt.% Ga, 25 wt.% In) on the matrix of Ag nanowires (NWs). With this structure, conductivity of 630 S/cm is maintained with no applied strain. The hybrid conductor showed high mechanical flexibility, with the percentage change in its resistance being small (12.5 % at bending radius: 0.5 mm). This percentage change in the resistance was much smaller that for the conductor without Ag-NWs (25.4 %). Moreover, the hybrid conductor showed excellent bending recovery performance at 50°C for 10 mins.
Authors : Sumanta Kumar Karan, Bhanu Bhusan Khatua
Affiliations : Materials Science Centre, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
Resume : Energy harvesting by nature-driven bio-compatible and bio-degradable materials responding to biomechanical activities has received great attention to develop an alternative energy source for next generation portable biomedical devices . Among various energy harvesting materials, piezoelectric nanogenerators (PNGs) are considered as the best renewable green energy sources for harvesting mechanical/bio-mechanical energy into electricity. Organic or inorganic materials based PNGs are very much incompatible and, considered as e-wastes for their high toxicity and complex synthesis methods . Spider silk (SS) fibers having remarkable protein sequence structure contain nature’s most outstanding mechanical properties and unrivalled elasticity along with biocompatibility and biodegradability. Here, using piezoresponse force microscopy (PFM), we report for the first time structure-dependent piezoelectric response of the SS at the molecular level and confirm that SS fiber shows vertical piezoelectric coefficient of ~0.36 pm/V. The fabricated SS based bio-piezoelectric nanogenerator (SSBPNG) provides excellent output performance and high energy conversion efficiency ~66%. The fabricated SSBPNG generates an output voltage of ~21.3 V and output current of ~0.68 μA, with instantaneous peak power density of ≈4.56 μW/cm2 under cyclic external mechanical pressure. The SSBPNG device is bio-compatible and ultra-sensitive towards physiological signal monitoring such as arterial pulse, coughing, swallowing responses which can further be useful for various possible potential e-health care monitoring applications. Keywords: Spider silk, Vertical piezoelectricity, Bio-piezoelectric nanogenerator, Self-powered, Biomedical sensor. References 1. Z. L. Wang, et. al, Science 312, 242-246 (2006). 2. S. K. Karan et. al, Nano Energy 49, 655-666 (2018).
Authors : Changyoon Jeong, Young-Bin Park*
Affiliations : UNIST (Ulsan National Institute of Science and Technolog)
Resume : Flexible sensors are essential components in electronic devices in various applications. High-performance, self-powered sensor is a highly interesting topic for a wide range of applications in artificial intelligence, prosthetics, automotive, and human-machine interactions. Triboelectric devices can be used as self-powered sensors for detecting mechanical stimuli. Self-powered sensors using triboelectric effect have been developed, but they have shown limitations such as bulky spacers, arch shapes and 3D structures, impeding flexible and thin structures. Here, we propose zinc oxide nanorods (ZnO NRs) grown on microscale curvature surfaces of carbon-fiber-reinforced plastics (CFRPs) having large surface areas for developing spacer-free, ultrathin, highly sensitive, and flexible triboelectric sensor (TESs), that is, mechanical sensors that allow measurement of deformations using triboelectrically-generated voltages. By fabricating hierarchical micro-nanostructures using novel methods, the TESs proposed are highly sensitive and ultrathin owing to maximized surface area and space-saving design. CFRPs having flexibility and microscale curvature surfaces can also detect tensile strains and have impact-sensing capability. Therefore, the self-powered TESs using CFRP composite with hierarchical micro-nanostructures are expected to find numerous applications in various fields.
Authors : Francesca Monforte (1,2), Mario Falsaperna (2), Anna Lucia Pellegrino (2), Corrado Bongiorno (1), Giovanni Mannino (1), Guglielmo Guido Condorelli (2)
Affiliations : 1: CNR-IMM, Strada VIII n°5 Zona Industriale, 95121 Catania, (Italy) 2: Dipartimento di Scienze Chimiche, Università di Catania and INSTM UdR Catania, Viale Andrea Doria 6, 95125, Catania, (Italy)
Resume : Metal Organic Frameworks (MOFs) are promising materials for a wide range of applications (like optics, electronics, gas sensing and energy storage) because of their high surface area, versatility, and chemical stability. MOFs are hybrid porous systems in which periodic arrangements of metal clusters are connected by organic ligands. Among all MOFs, MIL-101 and MIL-88 are two framework isomers built from the same precursors a trivalent metal center (mainly Cr) and a terephthalate ligand but with different connectivity. There are few examples of MIL films, which were carried out either through deposition techniques like Langmuir Blodgett and spin-coating, or through the solution growth (4 - 11 days of reaction) on gold substrates prefunctionalizated with self-assembled monolayers. This contribution proposes a fast synthetic route for the direct growth on Si of Fe-MIL films with different morphology, crystallinity and surface coverages depending on the experimental conditions. Isolated crystals of MIL-101 were directly grown from solution whereas carboxylates-based SAMs were used to obtain homogenous film consisted of MIL-88 crystals embedded in a Fe2O3 matrix. Thermal desorption experiments proved that isolated MIL-101 crystals are able to distinguish nitrobenzene from toluene. Finally, reported results showed that it is possible to integrate 3D porous MIL networks on Si surfaces to develop hybrid devices suitable for sensing applications.
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