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Investigation of post-thermal annealing on material properties of Cu-In-Zn-Se thin films

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Journal of Semiconductors 2017年第12期38卷 26-31页

作者： H.H.Güllü m.Parlak Central Laboratory Middle East Technical University(METU)Ankara 06800Turkey Department of Physics Middle East Technical University(METU)Ankara 06800Turkey Center for Solar Energy Research and Applications(GUNAm) METUAnkara 06800Turkey

The Cu-In-Zn-Se thin film was synthesized by changing the contribution of In in chalcopyrite CulnSe2 with Zn. The XRD spectra of the films showed the characteristic diffraction peaks in a good agreement with the quaternary Cu-In-Zn-Se compound. They were in the polycrystalline nature without any post-thermal process, and the main orientation was found to be in the （112） direction with tetragonal crystalline structure. With increasing annealing temperature, the peak intensities in preferred orientation became more pronounced and grain sizes were in increasing behavior from 6.0 to 25.0 nm. The samples had almost the same atomic composition of ***2. However, EDS results of the deposited films indicated that there was Se re-evaporation and/or segregation with the annealing in the structure of the film. According to the optical analysis, the transmittance values of the films increased with the annealing temperature. The absorption coefficient of the films was calculated as around 105 cm-1 in the visible region. moreover, optical band gap values were found to be changing in between 2.12 and 2.28 ev depending on annealing temperature. The temperature-dependent dark- and photo-conductivity measurements were carried out to investigate the electrical characteristics of the films.

关键词： annealing Cu-In-Zn-Se thin film

Effect of diode size and series resistance on barrier height and ideality factor in nearly ideal Au/n type-GaAs micro Schottky contact diodes

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Chinese Physics B 2010年第10期19卷 477-484页

作者： m. A. Yeganeh Sh. Rahmatallahpur A. Nozad R. K. mamedov Faculty of Physics Baku State University Academic Zahid Xlilov Küsi-23 AZ 1148 Iran material Research School POB 55515196 Binab Iran

Small high-quality Au/n type-GaAs Schottky barrier diodes （SBDs） with low reverse leakage current are produced using lithography. Their effective barrier heights （BHs） and ideality factors from current-voltage （I-V） characteristics are measured by a Pico ampere meter and home-built I-V instrument. In spite of the identical preparation of the diodes there is a diode-to-diode variation in ideality factor and barrier height parameters. measurement of topology of a surface of a thin metal film with atomic force microscope （AFm） shows that Au-n type-GaAS SD consists of a set of parallel-connected micro and nanocontacts diodes with sizes approximately in a range of 100-200 nm. Between barrier height and ideality factor there is an inversely proportional dependency. With the diameter of contact increasing from 5 μm up to 200 μm, the barrier height increases from 0.833 up to 0.933 ev and its ideality factor decreases from 1.11 down to 1.006. These dependencies show the reduction of the contribution of the peripheral current with the diameter of contact increasing. We find the effect of series resistance on barrier height and ideality factor.

关键词： Schottky barrier diodes conducting probe-atomic force microscope barrier height andideality factor

Electrical and Optical Properties of GaSe Thin Films

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Journal of materials Science & Technology 1997年第4期13卷 299-301页

作者： m. Ohyama(Dept. of Electrical Engineering, Tokyo National College of Technology, Tokyo, Japan) Dept. of Electrical Engineering Tokyo National College of Technology Tokyo Japan

The structure, electrical transport, and optical properties of GaSe films fabricated by means of radio-frequency (RF) magnetron sputtering in Ar were investigated. The as-sputtered GaSe films were amorphous, and their optical energy gap Eg are 1.9～2.6 ev. The effect of the synthesis conditions on the optical and electrical properties of the GaSe films has also been studied

关键词： Thin GaSe Electrical and Optical Properties of GaSe Thin Films

Gallium bismuth halide GaBi-X2 （X = I, Br, CI） monolayers with distorted hexagonal framework： Novel room- temperature quantum spin Hall insulators

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Nano Research 2017年第6期10卷 2168-2180页

作者： Linyang Li Ortwin Leenaerts Xiangru Kong Xin Chen mingwen Zhao Francois m. Peeters Department of Physics University of Antwerp Groenenborgerlaan 171 B-2020 Antwerp Belgium International Center for Quantum materials Peking University Beijing 100871 China School of Physics and State Key Laboratory of Crystal materials Shandong University Jinan 250700 China

Quantum spin Hall （QSH） insulators with a large topologically nontrivial bulk gap are crucial for future applications of the QSH effect. Among these, group III-V monolayers and their halides, which have a chair structure （regular hexagonal framework）, have been widely studied. Using first-principles calculations, we formulate a new structure model for the functionalized group III-V monolayers, which consist of rectangular GaBi-X2 （X = I, Br, C1） monolayers with a distorted hexagonal framework （DHF）. These structures have a far lower energy than the GaBi-X2 monolayers with a chair structure. Remarkably, the DHF GaBi-X2 monolayers are all QSH insulators, which exhibit sizeable nontrivial band gaps ranging from 0.17 to 0.39 ev. The band gaps can be widely tuned by applying different spin-orbit coupling strengths, resulting in a distorted Dirac cone.

关键词： quantum spin Hall (QSH)insulators,first-principles calculations,GaBi-X2 (X = L Br Cl)monolayers,distorted hexagonal framework,distorted Dirac cone

Advances in moS_2-Based Field Effect Transistors(FETs)

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Nano-micro Letters 2015年第3期7卷 203-218页

作者： Xin Tong Eric Ashalley Feng Lin Handong Li Zhiming m.Wang Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China

This paper reviews the original achievements and advances regarding the field effect transistor(FET) fabricated from one of the most studied transition metal dichalcogenides: two-dimensional mo S2. Not like graphene, which is highlighted by a gapless Dirac cone band structure, monolayer mo S2 is featured with a 1.9 e V gapped direct energy band thus facilitates convenient electronic and/or optoelectronic modulation of its physical properties in FET structure. Indeed,many mo S2 devices based on FET architecture such as phototransistors, memory devices, and sensors have been studied and extraordinary properties such as excellent mobility, ON/OFF ratio, and sensitivity of these devices have been exhibited. However, further developments in FET device applications depend a lot on if novel physics would be involved in them. In this review, an overview on advances and developments in the mo S2-based FETs are presented. Engineering of mo S2-based FETs will be discussed in details for understanding contact physics, formation of gate dielectric, and doping strategies. Also reported are demonstrations of device behaviors such as low-frequency noise and photoresponse in mo S2-based FETs, which is crucial for developing electronic and optoelectronic devices.

关键词： mo S2FETs engineering Low-frequency noise Optical properties mo S2sensors mo S2memory devices

Phase transformation from cubic ZnS to hexagonal ZnO by thermal annealing

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Journal of Semiconductors 2015年第3期36卷 19-22页

作者： K.mahmood m.Asghar N.Amin Adnan Ali Department of Physics GC University Faisalabad Department of Physics The Islamia University of Bahawalpur

We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. The ZnS thin films were grown on Si （001） substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction （XRD）, photoluminescence （PL）, four-point probe, scanning electron microscope （SEm） and energy dispersive X-ray diffraction （EDX）. The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a two- step process：（1） high-energy O atoms replaced S atoms in lattice during annealing process, and （2） S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log （resistivity） was found to be 3.1 ev. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 ev of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 ev and 2.5 ev respectively. SEm and EDX measurements were additionally performed to strengthen the argument.

关键词： ZnS phase transformation EDX XRD PL

含有并表达人乙型肝炎病毒表面抗原基因的转基因猪的制备

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实验动物与比较医学 1991年第1期22卷 65-65页

作者： Vasil ev I m.

本文阐述含有人乙型肝炎病毒表面抗原基因的转基因猪的制备,该基因可分泌在血清中。

关键词：转基因猪生物学活性

Benchmark Integral Cross Sections for Electron Impact Excitation of the n=2 States in Helium

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Plasma Science and Technology 2010年第3期12卷 348-352页

作者： m.HOSHINO H.KATO D.SUZUKI H.TANAKA I.BRAY D.V.FURSA S.J.BUCKmAN O.INGLFSSON m.J.BRUNGER Department of Physics Sophia University Centre for Antimatter-matter Studies Curtin University of Technology Centre for Antimatter-matter Studies Australian National University Department of Chemistry University of IcelandScience Institute Centre for Antimatter-matter Studies Flinders University

In this paper, we present integral cross sections （ICS） for electron impact excitation of the n = 2 levels in helium in the impact energy range of 23.5 ev to 35 ev. The ICS of each final state, 2^3S, 2^1S, 2^3P and 2^1P, has been determined by integration of the angular differential cross sections （DCS） over all of 0° to 180°, where those DCS were obtained from both our previous experiments and the extrapolation using the convergent close coupling calculation. The present experimental ICS for the optically allowed 21P transition state are also compared with those obtained from the BE f-scaling method. Very good agreement between the experimental and BE f-scaled 21P ICSs is generally found in the measured impact energy region.

关键词： low energy electron impact electronic excitations helium

Synthesis, Surface Characterization and Photocatalytic Activity of TiO_2 Supported on Almond Shell Activated Carbon

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Journal of materials Science & Technology 2014年第9期30卷 894-902页

作者： A.Omri S.D.Lambert J.Geens F.Bennour m.Benzina Laboratory of Water-Energy-Environment (LR35 Code: AD-10-02 National School of Engineers of SfaxUniversity of SfaxBP W 3038 Sfax Tunisia Laboratory of Chemical Engineering B6a University of LiègeB-4000 Liège Belgium Tunisian Chemical Group Sfax -Tunisia B.P 393/3018 Tunisia

Three types of photocatalysts were synthesized by metal organic chemical vapor deposition and impregnation methods using the almond shell activated carbon as support. These photocatalysts denoted by （TiO2/ASAC （V）, TiO2/ASAC （11） and TiO2/ASAC （12）） were characterized by scanning electron microscopy （SEm）, X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, diffuse reflectance spectroscopy （DRS） and nitrogen adsorption-desorption isotherms. SEm observation shows that TiO2 was deposited on activated carbon surface. XRD results confirm that TiO2 existed in a mixture of anatase and rutile phases. The DRS spectra show the characteristic absorption edge of TiO2 at approximate 380 nm corresponding to the optical band gap of 3.26 ev. Besides, FTIR spectrum indicated the presence of （Ti-O） groups. The specific surface area of photocatalysts decreased drastically in comparison with the original activated carbon. The catalysts were very efficient for the photodegradation of total organic carbon （TOC） from industrial phosphoric acid solution under UV irradiation. The kinetics of photocatalytic TOC degradation was found to follow a pseudo- first-order model. The prepared TiO2/ASAC showed high photoactivity for the photodegradation of TOC in the following order： TiO2/ASAC （V）〉 TiO2/ASAC （11）〉 TiO2/ASAC （12）〉 ASAC 〉 TiO2 （P25）.

关键词： Almond shell activated carbon Photocatalyst Vapor deposition Impregnation Total organic carbon