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  Subjects -> PHYSICS (Total: 780 journals)
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PHYSICS (565 journals)            First | 1 2 3 4 5 6 | Last

Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
Noise Notes     Full-text available via subscription   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 8)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 11)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 1)
Nuclear Receptor     Full-text available via subscription   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 4)
Open Journal of Microphysics     Open Access  
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 5)
Optofluidics, Microfluidics and Nanofluidics     Open Access   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 4)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 12)
Papers in Physics     Open Access  
Particle Physics Insights     Open Access   (Followers: 2)
Particuology     Hybrid Journal  
Pattern Recognition in Physics     Open Access   (Followers: 2)
Pergamon Materials Series     Full-text available via subscription  
Phase Transitions and Critical Phenomena     Full-text available via subscription   (Followers: 1)
Philosophical Magazine     Hybrid Journal   (Followers: 2)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 6)
Philosophy and Foundations of Physics     Full-text available via subscription  
Physica B: Condensed Matter     Hybrid Journal   (Followers: 6)
physica status solidi (a)     Hybrid Journal   (Followers: 1)
physica status solidi (b)     Hybrid Journal   (Followers: 1)
physica status solidi (c)     Hybrid Journal   (Followers: 1)
Physica Status Solidi - Rapid Research Letters     Hybrid Journal   (Followers: 1)
Physical Communication     Hybrid Journal   (Followers: 2)
Physical Review C     Full-text available via subscription   (Followers: 19)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 7)
Physical Sciences Data     Full-text available via subscription   (Followers: 1)
Physics - spotlighting exceptional research     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 2)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 2)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 3)
Physics and Materials Chemistry     Open Access  
Physics Essays     Full-text available via subscription  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 10)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
Physics Letters A     Hybrid Journal   (Followers: 9)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 26)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 6)
Physics of the Dark Universe     Open Access  
Physics of the Solid State     Hybrid Journal   (Followers: 3)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics Procedia     Partially Free   (Followers: 1)
Physics Reports     Full-text available via subscription   (Followers: 2)
Physics Research International     Open Access   (Followers: 1)
Physics Today     Hybrid Journal   (Followers: 34)
Physics World     Full-text available via subscription   (Followers: 3)
Physics-Uspekhi     Full-text available via subscription  
Physik in unserer Zeit     Hybrid Journal   (Followers: 1)
Physik Journal     Hybrid Journal  
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 3)
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Pramana     Open Access   (Followers: 9)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 453)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 21)
Progress in Planning     Hybrid Journal   (Followers: 1)
Progress of Theoretical and Experimental Physics     Open Access  
Quantum Electronics     Full-text available via subscription   (Followers: 3)
Quantum Measurements and Quantum Metrology     Open Access  
Quantum Studies : Mathematics and Foundations     Hybrid Journal   (Followers: 1)
Quarterly Journal of Mechanics and Applied Mathematics     Hybrid Journal   (Followers: 3)
Radiation Effects and Defects in Solids     Hybrid Journal   (Followers: 1)
Radiation Measurements     Hybrid Journal   (Followers: 2)
Radiation Physics and Chemistry     Hybrid Journal   (Followers: 1)
Radiation Protection Dosimetry     Hybrid Journal   (Followers: 2)
Radiation Research     Full-text available via subscription   (Followers: 3)
Radio Science     Full-text available via subscription   (Followers: 3)
Radiological Physics and Technology     Hybrid Journal   (Followers: 1)
Reflets de la physique     Full-text available via subscription  
Reports on Mathematical Physics     Full-text available via subscription  
Reports on Progress in Physics     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Physics     Full-text available via subscription  
Research in Drama Education     Hybrid Journal   (Followers: 12)
Research Journal of Physics     Open Access  
Results in Physics     Open Access   (Followers: 1)
Reviews in Mathematical Physics     Hybrid Journal  
Reviews of Accelerator Science and Technology     Hybrid Journal  
Reviews of Geophysics     Full-text available via subscription   (Followers: 20)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 17)
Revista Boliviana de Física     Open Access  
Revista Colombiana de Física     Open Access  
Revista Mexicana de Astronomía y Astrofísica     Open Access  
Revista Mexicana de Física     Open Access  
Revista mexicana de física E     Open Access  
Rheologica Acta     Hybrid Journal   (Followers: 3)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal  

  First | 1 2 3 4 5 6 | Last

Journal Cover   physica status solidi (c)
  [SJR: 0.471]   [H-I: 31]   [1 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1862-6351 - ISSN (Online) 1610-1642
   Published by John Wiley and Sons Homepage  [1610 journals]
  • Cover Picture: Phys. Status Solidi C 6/2015
    • Abstract: Cu2ZnSnS4 (CZTS) based material possesses highly suitable optical properties if it is used as an absorber layer of thin film solar cells (TFSCs). The main two reasons behind its suitability are as follows: optimal band gap energy of 1.5 eV, which is essential for the absorber layer and an absorption coefficient of over 104 cm–1 which covers a large portion of UV–visible light. In addition, CZTS is rare‐earth metal free and contains non‐toxic elements. Because of these significant features, CZTS is believed to be one of the promising materials for application in TFSCs. In the paper of Han Sung Yang and coworkers (pp. 708–712), Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells were fabricated using direct current sputtered Cu/Sn/Zn metallic layered precursors. A rapid thermal annealing process has been performed for sulfo‐selenization process of precursor under a sulfur and selenium atmosphere using S powder and Se pelltes. X‐ray diffraction and Raman spectroscopy investigations showed the formation of CZTSSe absorber layer without any secondary phase. X‐ray fluorescence spectroscopy showed a stoichiometric absorber layer being formed which is suitable for use in solar cells. The best thin film solar cell of CZTSSe showed a photovoltaic performance of 5.2% efficiency (Voc: 585.0 mV, Jsc: 17.0 mA/cm2 and FF: 52.0%). This is the highest efficiency reported for CZTSSe prepared from sputtered Cu/Zn/Sn precursors followed by sulfo‐selenization using powder sources.
      PubDate: 2015-06-18T05:14:50.406632-05:
      DOI: 10.1002/pssc.201570086
       
  • Issue Information: Phys. Status Solidi C 6/2015
    • PubDate: 2015-06-18T05:14:46.239808-05:
      DOI: 10.1002/pssc.201570087
       
  • Thermal decomposition of tungsten hexacarbonyl: CVD of W‐containing
           films under Pd codeposition and VUV assistance
    • Authors: Vladislav V. Krisyuk; Tatyana P. Koretskaya, Asiya E. Turgambaeva, Sergey V. Trubin, Ilya V. Korolkov, Olivier Debieu, Thomas Duguet, Igor K. Igumenov, Constantin Vahlas
      Abstract: Experiments on chemical vapor deposition of W(CO)6‐derived films on silicon substrates were carried out at total pressure of 5‐10 Torr within the temperature range of 250‐350 °C; in Ar or H2 flow. Metallic, carbide and oxide phases composed the obtained films. Deposition in presence of hydrogen results in the increase of the metal content in the film. Sublimed palladium hexafluoracetylacetonate Pd(hfa)2 was used for Pd catalytic promotion of the deposition process. Codeposition with Pd(hfa)2 in hydrogen increases W‐metal fraction and oxygen content while the Pd content is up to 10 at.%. Influence of vacuum ultraviolet (VUV) radiation from Xe excimer lamp (λ ∼172 nm) on the quality of the obtained films was investigated. It was found that VUV irradiation can reduce the oxygen‐content in the film while W‐metal fraction slightly increases. In all films, oxygen was in the form of WO3 and carbon was mainly incorporated as a graphite metastable phase. The influence of other chemical additives is discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:11.457133-05:
      DOI: 10.1002/pssc.201510020
       
  • Iron deposition on multi‐walled carbon nanotubes by fluidized bed
           MOCVD for aeronautic applications
    • Authors: Pierre Lassègue; Laure Noé, Marc Monthioux, Brigitte Caussat
      Abstract: The fluidized bed MOCVD process has been studied in order to uniformly deposit iron nanoparticles on the outer surface of multi‐walled carbon nanotubes (MWCNTs) tangled in balls of 388 µm in diameter. Using ferrocene as organometallic precursor at atmospheric pressure, various reactive atmospheres of deposition (under N2, air and H2) and an ozone O3 surface pre‐treatment of MWCNTs were tested. Around 10 g Fe/100 g MWNCTs were deposited during each run. Under N2 at 650 °C on the raw MWCNTs, nanoparticles formed of Fe and Fe3C were deposited which have catalyzed the formation of carbon nanofibers (CNFs). 20 h of ozone (O3) pre‐treatment improved the number and distribution of iron nanoparticles but without increasing the surface coverage of nanotubes. A more intense amorphous carbon deposit also appeared. Under H2 at 550 °C, the amorphous carbon was partly eliminated but fewer iron nanoparticles were present. Under air at 450 °C, a part of the MWCNTs was lost and a Fe2O3 shell covered each remaining MWCNTs ball. New works are in progress to increase more markedly the surface reactivity of MWCNTs and to deposit pure iron. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:10.320753-05:
      DOI: 10.1002/pssc.201510036
       
  • PEALD AlN: Controlling growth and film crystallinity
    • Authors: Sourish Banerjee; Antonius A. I. Aarnink, Robbert van de Kruijs, Alexey Y. Kovalgin, Jurriaan Schmitz
      Abstract: We report on the growth kinetics and material properties of aluminium nitride (AlN) films deposited on Si(111), with plasma enhanced atomic layer deposition (PEALD). Tri‐methyl aluminium (TMA) and NH3‐plasma were used as the precursors. The ALD window was identified in terms of the process parameters, and it showed that a 0.1 s of TMA pulse, 8 s of NH3‐plasma pulse, and 350 °C were the optimal conditions for ALD to occur. In‐situ spectroscopic ellipsometry (SE), using a Cauchy optical model, was used to monitor the film growth in real time. The composition of the as‐grown AlN films were determined by X‐ray photoelectron spectroscopy (XPS), which revealed Al/N compositions of approximately 46% and 53%, also with low impurity (O, C) levels. The film crystallinity, measured with grazing incidence X‐ray diffraction (GIXRD), showed polycrystalline hexagonal (wurtzitic) crystalline planes. Finally, several techniques were employed to influence the film crystallinity. These included: ALD at different plasma powers and temperatures, in‐situ treatment of the Si(111) wafer with different plasma parameters (composition, power, duration) prior to deposition, and ALD on Si(100) and SiO2 substrates. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:09.20925-05:0
      DOI: 10.1002/pssc.201510039
       
  • Problems of hydrogen high‐temperature activation by chemical vapor
           deposition of diamond films
    • Authors: Alexey Rebrov; Ivan Yudin
      Abstract: The presented study is the original analysis of hydrogen flow in channels with heterogeneous physical‐chemical reactions. It provides the possibility to evaluate, calculate and predict unknown constants of heterogeneous reactions, using experimental data on dissociation at low pressures. It can be the base of conclusive data for computational modelling of CVD, using high velocity gas mixture flows. Till now there was no way to calculate the flow of hydrogen in tungsten channels in regimes of diamond deposition. The presented research allows formulate the problem of studies the heterogeneous reactions not only for diamond deposition. In the result of precise measurements of fragment fluxes behind heat‐resistant capillaries from refractory metals or ceramics at low pressure and direct statistical simulation of gas mixture flows one can determine collisional constants for simple molecules. Such approach is more preferential than expensive and sophisticated molecular beam methods. So possibilities of CVD can be extended. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:08.319473-05:
      DOI: 10.1002/pssc.201510042
       
  • A computational view on vapour phase coagulation of nanoparticles
           synthesized by atmospheric pressure PECVD
    • Authors: Maxim V. Mishin; Kirill Y. Zamotin, Vera S. Protopopova, Andrey A. Uvarov, Leonid A. Filatov, Marina V. Baryshnikova, Irina K. Boricheva, Sergey E. Alexandrov
      Abstract: The article covers the computational framework providing an insight on vapour phase coagulation of nanoparticles synthesized by atmospheric pressure PECVD in an RF capacitive discharge. The proposed model is based on the solution of motion equations for neutral and charged nanoparticles in the plasma downstream area featuring a nonuniform distribution of electric potential. Within the model particles collisions are accounted by an O'Rourke derived stochastic method, reduction of computational time is attained by division of the nanoparticle stack into parcels. We argue that nanoparticles are mainly synthesized in the plasma downstream area. Size distribution of the particles is governed by their uneven motion in the nonuniform electric field. We demonstrate that particles of tens of nanometer in diameter result from coagulation of neutral nanoparticles, whereas the larger nanoparticles result from coagulation of charged particles. The model shows that charged particles trapped in the potential well in the vicinity of the discharge electrode grow up to micron size. The proposed model is validated by the experimental results of silicon dioxide nanoparticles synthesis; it may be extended to a vast range of materials provided certain modifications of the particles motion equations are done. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:07.19109-05:0
      DOI: 10.1002/pssc.201510044
       
  • AACVD synthesis of catalytic gold nanoparticle‐modified cerium(IV)
           oxide thin films
    • Authors: Meghan Evans; Francesco Di Maggio, Chris Blackman, Gopinathan Sankar
      Abstract: Co‐deposition of Ce(dbm)4 and NH4AuCl4 precursors in acetone at 500 °C via AACVD results in deposition of crystalline CeO2 thin films containing/decorated with metallic gold. These particles are estimated to be ∼ 70 nm in size via optical methods. Preliminary testing of catalytic activity showed the materials were surprisingly catalytically active given the very small amounts of gold present and the large estimated particle size, although the presence of smaller catalytically active particles could not be discounted. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T06:10:06.081978-05:
      DOI: 10.1002/pssc.201510055
       
  • Atomic redistribution of implanted Fe and associated defects around moving
           SiO2/Si interfaces
    • Authors: Anthony De Luca; Nelly Burle, Alain Portavoce, Catherine Grosjean, Stéphane Morata, Michaël Texier
      Abstract: The behaviour of Fe atoms at the Si/SiO2 interface, as a modelisation of an involuntary Fe contamination before or during the oxidation process has been studied in Fe‐implanted wafers. As‐implanted and oxidized wafers were characterized by SIMS, APT, HR‐TEM and STEM‐HAADF. Successive steps of Fe segregation, iron‐silicide precipitation and dissolution were identified. As expected for such a temperature range, the iron‐silicide precipitates adopt the FeSi2 structure. Fe enriched phases were also identified in an advanced step of precipitation. Dynamic mechanisms are proposed, taking into account the competitive oxidizing of precipitates and silicon matrix, to understand the different steps and precipitation phases observed in the samples during the non‐equilibrium conditions due to the oxide layer growth. The correlation between the formation of characteristic pyramidal defects at the SiO2/Si interface and the presence of the Fe‐rich precipitates is explained. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:47.512159-05:
      DOI: 10.1002/pssc.201400233
       
  • Oxygen‐related defects: minority carrier lifetime killers in
           n‐type Czochralski silicon wafers for solar cell application
    • Authors: I. Kolevatov; V. Osinniy, M. Herms, A. Loshachenko, I. Shlyakhov, V. Kveder, O. Vyvenko
      Abstract: Many authors (Haunschild et al., Phys. Status Solidi RRL 5, 199–201 (2012) [1]) reported about areas in Cz‐Si with an extremely low lifetime of minority carriers after high temperature stages of solar cell manufacture. In such regions the minority carrier lifetime may be fallen 100 times after annealing, what leads to a considerable drop in the solar cell efficiency. In present work the electrical and structural properties of phosphorus doped Bosch Cz‐Si wafers with degrading areas were studied by means of photoluminescence, deep level transient spectroscopy, transmission electron microscopy, electron energy loss spectroscopy and Fourier transform infrared spectroscopy. Based on these data it is concluded that the dominant recombination channel in the degrading areas is related to strained oxygen precipitates. We found electronic states of traps which may cause their formation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:44.594012-05:
      DOI: 10.1002/pssc.201400293
       
  • Optical properties and core state of AlN‐BN ternary compound by ab
           initio calculations
    • Authors: Masashi Yamashita; Noriaki Hamada, Hiroki Funashima, Masato Yoshiya
      Abstract: By ab initio calculation using the ABCAP code, energy shifts of core levels and optical properties of B‐incorporated AlN (AlBN) were examined through comparison with experimental spectra measured from the thin film. Good agreements of complex refractive indices, n and k, with experiment were obtained for pure AlN and pure BN. However, when B content is increased in AlBN, substantial disagreement is found between experiment and calculation that assumed either wurtzite or graphite‐like structure for clarity. These results suggest that AlBN with ca. 30% is neither complete solid solution nor grain‐level mixture of graphite like BN and AlN. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:43.592773-05:
      DOI: 10.1002/pssc.201400325
       
  • Effects of surface nature of different semiconductor substrates on the
           plasma enhanced atomic layer deposition growth of Al2O3 gate dielectric
           thin films
    • Authors: Emanuela Schilirò; Giuseppe Greco, Patrick Fiorenza, Cristina Tudisco, Guglielmo Guido Condorelli, Salvatore Di Franco, Fabrizio Roccaforte, Raffaella Lo Nigro
      Abstract: In this work, we present a systematic study on the effects of surface nature of two different substrates such as Si(100) and AlGaN/GaN (0001) before atomic layer deposition (ALD) growth of Al2O3 thin films. The Si and AlGaN/GaN surfaces were treated either with: H2O2:H2SO4 (1:3 piranha solution) for 10 minutes and H2O:HF (10:1) for 5 minutes. After surface pretreatment, Al2O3 was immediately deposited at 250 °C by Plasma Enhanced ALD from trimethylaluminum precursor. The film thicknesses were measured to be 28 nm using transmission electron microscopy and different structural evolution has been observed under electron beam analysis, rearraging from amorphous as‐deposited films to epitaxial films depending on the substrate type. Surface morphology obtained by atomic force microscopy in tapping mode shows scattered three‐dimensional nucleation of Al2O3 thin films on Si(001) substrate, while deposition on AlGaN/GaN(0001) resulted in smooth Al2O3 layers. Moreover, X‐ray photoelectron spectroscopy investigation demonstrated a different interfacial interaction between the Al2O3 films and the two different substrates. However, analogous dielectric properties have been evaluated for both films deposited on the two Si(100) and AlGaN/GaN (0001) substrates. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:39.365014-05:
      DOI: 10.1002/pssc.201510016
       
  • Enhanced optical performance of APCVD zinc oxide via post growth plasma
           treatment at atmospheric pressure
    • Authors: John L. Hodgkinson; Heather M. Yates, David W. Sheel
      Abstract: The use of atmospheric pressure (AP) CVD to produce highly developed Transparent Conducting oxides (TCO) for thin film photovoltaic systems has significant potential to reduce manufacturing costs and increase the product scope via in‐line processing compared to off‐line, low pressure techniques. A further advantage of APCVD is the ability control surface morphology via growth parameters, a key factor in controlling the distribution of scattered light at the TCO/absorber interface. The nano‐scale features may be further optimised via post growth etching, for example, to round sharp vertices or induce or exaggerate texture in a film material that is intrinsically smooth. This is normally achieved via low pressure plasma treatments or wet chemical processes, hence the presented novel AP plasma approach here offers reduced capital costs combined with ease of scalability and process integration. In this work we describe the multi‐scale manipulation of an APCVD grown ZnO via surface morphological modification, achieved by the application of an atmospheric pressure plasma etch system. The modified surfaces are evaluated for optical and morphological properties. Initial research has shown that under the correct plasma etch conditions, optical haze can be increased by as much as 20%, with the crucial additional ability to also tailor the film surface features. The use of audio frequency and sub‐microsecond pulsed plasmas for etching are compared in terms of activity and control. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:38.398108-05:
      DOI: 10.1002/pssc.201510011
       
  • Structural studies of Al thin layer on misoriented GaAs(100) substrate by
           transmission electron microscopy
    • Authors: M. V. Lovygin; N. I. Borgardt, I. P. Kazakov, M. Seibt
      Abstract: A thin Al layer has been grown on a misoriented GaAs(100) substrate by molecular beam epitaxy and its structure has been studied by means of transmission electron microscopy. The metal layer is formed as grains of three orientations Al(100), Al(110) and Al(110)R. Digital analysis of dark‐field micrographs made it possible to obtain their grain sizes and relative coverage areas. By comparison with an Al layer grown on an exactly oriented GaAs(100) substrate it has been found that on the vicinal surface the relative coverage area and grain size of the Al(110)R orientation increase and the Al(100) relative coverage area decreases. This is attributed to surface atomic steps, which have been visualized in high‐resolution micrographs. The edge misfit dislocation system at the Al/GaAs interface has been revealed, which is insensitive to the substrate misorientation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:37.390678-05:
      DOI: 10.1002/pssc.201400357
       
  • Turbostratic pyrocarbon structure study by means of exit wave
           reconstruction from high‐resolution transmission electron microscopy
           
    • Authors: A. S. Prikhodko; N. I. Borgardt, M. Seibt
      Abstract: This paper reports results of turbostratic pyrolytic carbon structure study using high‐resolution electron microscopy techniques. We obtained a through‐focus series of images and noted that domain‐like contrast features were varied depending on defocus of the objective lens. Since these features are commonly explained in terms of the domain model of pyrocarbon structure we carried out exit wave reconstruction to obtain the phase map. The visual appearance of the map indicates that the ribbon‐like model more appropriately describes the pyrocarbon structure in comparison to the domain model. In the context of the ribbon‐like model we constructed a test carbon structure using the recovered phase map and molecular dynamics modeling. After determination of atomic positions we simulated high‐resolution images of the structure. Our calculations demonstrated that high‐resolution micrographs showing domain‐like image features can be obtained without carbon domains presented in the actual structure. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:36.385021-05:
      DOI: 10.1002/pssc.201400363
       
  • Two‐energy‐scale model for description of the thermal
           quenching of photoluminescence in disordered Ga(As,Bi)
    • Authors: M. K. Shakfa; M. Wiemer, P. Ludewig, K. Jandieri, K. Volz, W. Stolz, S. D. Baranovskii, M. Koch
      Abstract: The thermal quenching of the photoluminescence (PL) intensity in Ga(As,Bi)/GaAs heterostructures is studied experimentally and theoretically. We observed an anomalous plateau in the PL thermal quenching at intermediate temperatures under low excitation conditions. Our theoretical analysis based on a well‐approved theoretical approach shows that this peculiar behavior of the temperature‐dependent PL intensity cannot be interpreted assuming a single‐scale monotonously energy‐dependent density of localized states (DOS). Experimental data clearly point at a non‐monotonous DOS with at least two energy scales. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:35.334395-05:
      DOI: 10.1002/pssc.201400369
       
  • In‐situ observation of chemical vapor deposition using SiHCl3 and
           BCl3 gases
    • Authors: Ayumi Saito; Kento Miyazaki, Misako Matsui, Hitoshi Habuka
      Abstract: The lowest temperature for initiating the film deposition was evaluated by in situ monitoring using a highly sensitive langasite crystal microbalance (LCM) in order to produce a thin boron doped silicon film using trichlorosilane gas and boron trichloride gas at low temperatures. The thin films of silicon, boron and boron‐doped silicon were individually formed from the trichlorosilane gas, boron trichloride gas and their gas mixture, respectively, on the LCM. The silicon film deposition occurred between 570 and 600 °C, while the boron film deposition occurred between 470 and 530 °C. The film deposition from both gases occurred at temperatures higher than 530 °C. Based on secondary ion mass spectrometry measurements, the boron‐doped silicon film was determined to be formed on the silicon substrate at 570 °C. Thus, the LCM could be useful for developing a thin film formation process including that for doping. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:34.349122-05:
      DOI: 10.1002/pssc.201510002
       
  • Alumina thin films prepared by direct liquid injection chemical vapor
           deposition of dimethylaluminum isopropoxide: a process‐structure
           investigation
    • Authors: Loïc Baggetto; Jérôme Esvan, Cédric Charvillat, Diane Samélor, Hugues Vergnes, Brigitte Caussat, Alain Gleizes, Constantin Vahlas
      Abstract: The development of a new process to obtain amorphous alumina thin films is presented. We show for the first time the direct liquid injection chemical vapor deposition (DLI CVD) of alumina thin films using dimethylaluminum isopropoxide (DMAI) precursor in two oxidizing atmospheres. At high process temperature (500‐700 °C), the film growth takes place in the presence of O2 whereas at low temperature (150‐300 °C) H2O vapor is used. The materials characteristics, such as the surface morphology and roughness (SEM and AFM), crystal structure (XRD), composition (EPMA) and chemistry (XPS) are discussed in detail. Very smooth films, with typical roughness values lower than 2.0 nm are obtained. The thin films are all composed of an amorphous material with varying composition. Supported by both EPMA and XPS results, film composition evolves from a partial oxyhydroxide to a stoichiometric oxide at low deposition temperature (150‐300 °C) in the presence of H2O. At higher growth temperature (500‐700 °C) in the presence of O2, the composition changes from that of a stoichiometric oxide to a mixture of an oxide with aluminum carbide. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:50:33.183598-05:
      DOI: 10.1002/pssc.201510009
       
  • Structural, electrical and luminescent properties of ZnO:Li films
           fabricated by screen‐printing method on sapphire substrate
    • Authors: L. Khomenkova; V. I. Kushnirenko, M. M. Osipyonok, O. F. Syngaivsky, T. V. Zashivailo, G. S. Pekar, Yu. O. Polishchuk, V. P. Kladko, L. V. Borkovska
      Abstract: Undoped and Li‐doped ZnO thick films were fabricated by a screen‐printing technique on sapphire substrate. The effect of sintering temperature (TS = 800, 900 and 1000 °C) and Li content ([Li] = 0.003, 0.03 and 0.3 wt%) on the photoluminescence (PL), electrical and structural properties of the films was investigated. The X‐ray diffraction shows that all the films are polycrystalline with a wurtzite structure. It is found that both high sintering temperature and low Li content favour formation of the low‐resistive films with an enhanced UV emission. The high Li content stimulates an appearance of semi‐insulating behaviour of the films and deteriorated PL properties. It is shown that the effect of Li‐doping on light‐emitting properties of the films consists mainly in the modification of the film crystallinity and the engineering of the concentration of intrinsic defects. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:40:18.406098-05:
      DOI: 10.1002/pssc.201400232
       
  • Control of extended defects in cast and seed cast Si ingots for
           photovoltaic application
    • Authors: Takashi Sekiguchi; Karolin Jiptner, Ronit R. Prakash, Jun Chen, Yoshiji Miyamura, Hirofumi Harada, S. Nakano, Bin Gao, Koichi Kakimoto
      Abstract: We discuss the defect evolution in conventional cast and seed cast Si ingot growths for photovoltaic application. Three different cast Si ingots were grown in one directional solidification furnace. The two extremes are the seed cast ingots (mono‐Si), where growth starts from monocrystalline silicon seeds, and the multicrystalline silicon grown from small randomly oriented grains. The conventional multicrystalline (mc‐) cast Si ingots are grown without any seeds and have grain structures in between the two extremes. It was found that in mc‐Si the evolution of grain boundaries take place in several steps. On the other hand, the major defects in mono‐Si are dislocations and are generated by stress due to thermal gradient in the ingot. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:40:17.44391-05:0
      DOI: 10.1002/pssc.201400230
       
  • EBIC and LBIC investigations of dislocation trails in Si
    • Authors: O. V. Feklisova; V. I. Orlov, E. B. Yakimov
      Abstract: The recombination properties of dislocation trails formed behind moving dislocations in plastically deformed Si have been investigated by the electron beam induced current and laser beam induced current methods. It is found that for dislocations moving with a velocity lower than 10–5cm/s the contrast of dislocation trails does not noticeably depend on the velocity value. It is shown that the dislocation type is not unique parameter determining the recombination activity of defects in the dislocation trails. A dislocation bending in near surface layers is found also to affect the defect formation in the dislocation trails. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:40:16.185628-05:
      DOI: 10.1002/pssc.201400223
       
  • Impact of bismuth incorporation into (Ga,Mn)As thin films on their
           structural and magnetic properties
    • Authors: K. Levchenko; T. Andrearczyk, J. Z. Domagala, T. Wosinski, T. Figielski, J. Sadowski
      Abstract: Structural and magnetic properties of thin films of the (Ga,Mn)(Bi,As) quaternary diluted magnetic semiconductor grown by the low‐temperature molecular‐beam epitaxy technique on GaAs substrates have been investigated. High‐resolution X‐ray diffraction has been applied to characterize the structural quality and misfit strain in the films. Ferromagnetic Curie temperature and magneto‐crystalline anisotropy of the films have been examined by using SQUID magnetometry and low‐temperature magneto‐transport measurements. Post‐growth annealing treatment of the films has been shown to reduce the strain in the films and to enhance their Curie temperature. Significant increase in the magnitude of magneto‐transport effects caused by incorporation of a small amount of Bi into the films is interpreted as a result of enhanced spin‐orbit coupling in the (Ga,Mn)(Bi,As) films. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:40:14.989456-05:
      DOI: 10.1002/pssc.201400219
       
  • Extended defects in MBE‐grown CdTe‐based solar cells
    • Authors: Karolina Wichrowska; Tadeusz Wosinski, Sławomir Kret, Michał Rawski, Oksana Yastrubchak, Sergij Chusnutdinow, Grzegorz Karczewski
      Abstract: Extended defects in the p ‐ZnTe/n ‐CdTe heterojunctions grown by the molecular‐beam epitaxy technique on two different substrates, GaAs and CdTe, have been investigated by deep‐level transient spectroscopy (DLTS) and transmission electron microscopy (TEM). Four hole traps, called H1 to H4, and one electron trap, called E3, have been revealed in the DLTS spectra measured for the heterojunctions grown on the GaAs substrates. The H1, H3, H4 and E3 traps have been attributed to the electronic states of dislocations on the ground of their logarithmic capture kinetics. The DLTS peaks associated with the H1 and E3 traps were not observed in the DLTS spectra measured for the heterojunction grown on the CdTe substrate. They are most likely associated with threading dislocations generated at the mismatched interface with the GaAs substrate. Cross‐sectional TEM images point out that they are dislocations of the 60°‐type. In both the types of heterojunctions the H4 trap was observed only under forward‐bias filling pulse, suggesting that this trap is associated with the CdTe/ZnTe interface. In addition, TEM images revealed also the presence of intrinsic and extrinsic stacking faults in the CdTe layers, which may considerably affect their electronic properties. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-05T05:40:09.253278-05:
      DOI: 10.1002/pssc.201400217
       
  • Process‐structure‐properties relationship in direct liquid
           injection chemical vapor deposition of amorphous alumina from aluminum
           tri‐isopropoxide
    • Authors: Pierre‐Luc Etchepare; Loïc Baggetto, Hugues Vergnes, Diane Samélor, Daniel Sadowski, Brigitte Caussat, Constantin Vahlas
      Abstract: We propose a method to apply amorphous alumina films on the inner surface of glass containers aiming to improve their hydrothermal barrier property. We have carried out alumina deposition on Si substrates as a function of deposition temperature to determine the physico‐chemical properties of the thin film materials, and on glass containers to evaluate the influence of post‐deposition hydrothermal ageing on the films properties. Film preparation has been achieved by metal‐organic chemical vapor deposition (MOCVD), using tri‐isopropoxide aluminum (ATI) dissolved in anhydrous cyclohexane as precursor, in a temperature range between 360 °C and 600 °C. A direct liquid injection technology is used to feed the reactor in a controlled and reproducible way. The amorphous alumina films have been characterized by several techniques such as XRD, EPMA, XPS, SEM, AFM and scratch‐test method. Films are amorphous and hydroxylated at 360 and 420 °C and close to stoichiometric at 490 and 560 °C. Hydrothermal ageing simulated by a standard sterilization cycle modifies the adhesion and surface morphology of the alumina film on glass containers to a rough, porous and non‐adhesive layer. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T12:51:45.89562-05:0
      DOI: 10.1002/pssc.201510037
       
  • MOCVD growth of Pt films using a novel Pt(IV) compound as a precursor
    • Authors: Svetlana I. Dorovskikh; Galina I. Zharkova, Ludmila N. Zelenina, Igor P. Asanov, Danila B. Kal'nii, Vasily V. Kokovkin, Yuri V. Shubin, Tamara V. Basova, Natalia B. Morozova
      Abstract: The Me3Pt(acac)Py compound, trimethyl(pentane‐2,4‐dionato)platinum(IV)pyridine, is synthesized and, for the first time, characterized by physico‐chemical methods to determine its chemical composition (elemental analysis, IR‐spectroscopy) and thermal behavior (thermogravimetric (TG), differential thermal analyses (DTA), differential scanning calorimetry (DSC), tensometric flow method). Due to its good volatility ln(p/p°) = 16.47–9699/T(K) at moderate temperatures (393–414 K) the compound is offered as a promising precursor for growth of Pt films by metal‐organic chemical vapour deposition (MOCVD). The Pt films deposited on various substrates including Si(100), Ta, Ti substrates, cathodes and anodes of the electrodes for pacemakers are investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). The electrochemical characteristics of Pt films are also determined. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:14.053394-05:
      DOI: 10.1002/pssc.201510045
       
  • Titania‐based photocatalytic coatings on stainless steel hospital
           fixtures
    • Authors: S. Krumdieck; S. S. Miya, D. Lee, S. Davies‐Talwar, C. M. Bishop
      Abstract: A scaled‐up pulsed‐pressure MOCVD system was used to deposit TiO2 coatings from tetra‐isopropoxide precursor solution on stainless steel substrates and on 3‐D objects. The objective of the work is the production of antimicrobial coatings for handles in health care facilities. Antimicrobial coatings are sought to manage the transmission of hospital acquired infections (HAI's), which are reported to cost around one million pounds per annum in the UK alone. Titania is a promising material for this application due to the photocatalytic production of reactive oxygen species that are crucial for the destruction of organic pathogens. TiO2 coatings of 0.2 to 13 µm thickness were deposited at temperatures between 375 °C and 475 °C. The crystallite size and photocatalytic activity are influenced by deposition temperature. No dependence of stoichiometry on the deposition temperature has been observed. The films on stainless steel exhibit reasonably good photocatalytic performance. The photocatalytic performance and the stoichiometry improve with the film thickness. A three dimensional object (door handle) was coated with good conformity. The reactor scale‐up for coating production on door handles is proposed for future wear and hygiene performance testing. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:12.974158-05:
      DOI: 10.1002/pssc.201510040
       
  • Electrical characteristics of vapor deposited amorphous MoS2
           two‐terminal structures and back gate thin film transistors with Al,
           Au, Cu and Ni‐Au contacts
    • Authors: Dimitrios N. Kouvatsos; George Papadimitropoulos, Thanassis Spiliotis, Maria Vasilopoulou, Davide Barreca, Alberto Gasparotto, Dimitris Davazoglou
      Abstract: Amorphous molybdenum sulphide (a‐MoS2) thin films were deposited at near room temperature on oxidized silicon substrates and were electrically characterized with the use of two‐terminal structures and of back‐gated thin film transistors utilizing the substrate silicon as gate. Current‐voltage characteristics were extracted for various metals used as pads, showing significant current variations attributable to different metal‐sulphide interface properties and contact resistances, while the effect of a forming gas anneal was determined. With the use of heavily doped silicon substrates and aluminum backside deposition, thin film transistor (TFT) structures with the a‐MoS2 film as active layer were fabricated and characterized. Transfer characteristics showing a gate field effect, despite a leakage often present, were extracted for these devices, indicating that high mobility devices can be fabricated. SEM and EDXA measurements were also performed in an attempt to clarify issues related to material properties and fabrication procedures, so as to achieve a reliable and optimized a‐MoS2 TFT fabrication process. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:11.900312-05:
      DOI: 10.1002/pssc.201510025
       
  • Formation of hydroxylapatite on CVD deposited titania layers
    • Authors: Marina Baryshnikova; Leonid Filatov, Maxim Mishin, Anastasia Kondrateva, Sergey Alexandrov
      Abstract: Bioactive coatings on medical implants can be prepared from titanium dioxide due to its ability to induce the formation of hydroxylapatite (HA) from physiological solutions. In this study TiO2 layers were formed by chemical vapor deposition at different substrate temperatures in order to controllably change their structure from amorphous to consisting of preferentially oriented anatase crystallites. To evaluate the influence of phase composition and surface morphology of the deposited layers on their ability to form HA titania samples were immersed in Dulbecco's phosphate‐buffered saline (DPBS). The obtained results showed that structure of TiO2 layers determines the structure of HA formed on their surface. Polycrystalline titania layers with random orientation of anatase crystallites are the most favorable for intensive nucleation and formation of continuous HA coatings in DPBS solution. The textured TiO2 layers with smooth surface enhanced formation of HA deposits which consisted of sparsely distributed large separate grains. On the basis of the experimental results it was proposed that formation of hydroxylapatite nuclei on the surface of titania layers occurs by a mechanism of epitaxial growth. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:10.483646-05:
      DOI: 10.1002/pssc.201510015
       
  • First‐principles study on alkali‐metal effect of Li, Na, and K
           in Cu2ZnSnS4 and Cu2ZnSnSe4
    • Authors: Tsuyoshi Maeda; Atsuhito Kawabata, Takahiro Wada
      Abstract: The substitution energies and migration energies of the alkali‐metals of Li, Na, and K atoms in Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) were investigated by first‐principles calculations. The migration energies of Li, Na, and K atoms in CZTS and CZTSe are obtained by a combination of linear and quadratic synchronous transit (LST/QST) methods and a nudged elastic band (NEB) method. For CZTS and CZTSe, the substitution energies of NaCu and NaZn are much smaller than that of NaSn. The substitution energy of NaZn is comparable to that of NaCu, indicating that NaCu and NaZn are easily formed in CZTS and CZTSe. The substitution energies of the LiCu and LiZn atoms are smaller than those of NaCu and NaZn, while substitution energies of KCu and KZn atoms are much larger than those of NaCu and NaZn. Therefore, it is difficult to form KCu and KZnin CZTS and CZTSe. The theoretical migration energies of Na atom at Cu site to the nearest Cu vacancy (NaCu→VCu) and Na atom at Zn site to the nearest Cu vacancy (NaZn→VCu) are much smaller than those of (NaSn→VCu). The migration energies of (NaCu→VCu) and (NaZn→VCu) in CZTS and CZTSe are comparable to that of Na atom at Cu site to Cu vacancy (NaCu→VCu) in CIS. The mechanism for the alkali‐metal effect of Li, Na, and K in the Cu2ZnSn(S,Se)4 films during the post‐deposition treatment of LiF, NaF, and KF is discussed on the basis of the calculated substitution and migration energies. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:09.204619-05:
      DOI: 10.1002/pssc.201400345
       
  • Si‐co‐doped CuAlS2:Mn conductive phosphor thin films prepared
           by electron beam evaporation using phosphor powder pellets
    • Authors: Hideki Kawaguchi; Tadashi Ishigaki, Takayoshi Adachi, Yuki Oshima, Koutoku Ohmi
      Abstract: Si‐codoped CuAlS2:Mn thin films have been prepared by EB evaporation using the phosphor powder as evaporation source pellets. The selective substitution of Mn centers for both Cu and Al has been first achieved for thin film samples. A currently obtained maximum quantum efficiency is about 9% for an orange emission due to Mn centers substituted for Cu, and 3% for a red emission due to Mn centers substituted for Al. It has been found that the conductivity predominantly depends on the Al/Cu compositional ratio of the thin films. The origin of carriers is considered to be the Cu‐Al mutual substitution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-26T05:40:08.209394-05:
      DOI: 10.1002/pssc.201400326
       
  • Chemical vapor deposition and analysis of thermally insulating ZrO2 layers
           on injection molds
    • Authors: Burak Atakan; Victoria Khlopyanova, Simon Mausberg, Frank Mumme, Adrian Kandzia, Christian Pflitsch
      Abstract: High quality injection molding requires a precise control of cooling rates. Thermal barrier coating (TBC) of zirconia with a thickness of 20‐40 µm on polished stainless steel molds could provide the necessary insulating effect. This paper presents results of zirconia deposition on stainless steel substrates using chemical vapor deposition (CVD) aiming to provide the process parameters for the deposition of uniform zirconia films with such a thickness. The deposition was performed with zirconium (IV) acetylacetonate (Zr(C5H7O2)4) as precursor and synthetic air as co‐reactant, which allows deposition at temperatures below 600 °C. The experiments were carried out in a hot‐wall reactor at pressures between 7.5 mbar and 500 mbar and in a temperature range from 450 °C to 600 °C. Important growth parameters were characterized and growth rates between 1 and 2.5 µm/h were achieved. Thick and well adhering zirconia layers of 38 µm could be produced on steel within 40 h. The transient heat transfer rate upon contact with a hot surface was also evaluated experimentally with the thickest coatings. These exhibit a good TBC performance. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-19T05:30:13.425646-05:
      DOI: 10.1002/pssc.201510033
       
  • Investigation of structural, morphological and electrical properties of
           APCVD vanadium oxide thin films
    • Authors: Georgios Papadimitropoulos; Ioannis Kostis, Stelios Trantalidis, Athanasios Tsiatouras, Maria Vasilopoulou, Dimitris Davazoglou
      Abstract: Vanadium oxide films were chemically vapor deposited (CVD) on oxidized Si substrates covered with CVD tungsten (W) thin films and on glass substrates covered with indium tin oxide (ITO) films, using vanadium(V) oxy‐tri‐isopropoxide (C9H21O4V) vapors. X‐ray diffraction (XRD) measurements showed that the deposited films were composed of a mixture of vanadium oxides; the composition was determined mainly by the deposition temperature and less by the precursor temperature. At temperatures up to 450 °C the films were mostly composed by monoclinic VO2. Other peaks corresponding to various vanadium oxides were also observed. X‐ray microanalysis confirmed the composition of the films. The surface morphology was studied with atomic force microscopy (AFM) and scanning electron microscopy (SEM). These measurements revealed that the morphology strongly depends on the used substrate and the deposition conditions. The well‐known metal‐insulator transition was observed near 75 °C for films mostly composed by monoclinic VO2. Films deposited at 450 °C exhibited two transitions one near 50 °C and the other near 60 °C possibly related to the presence of other vanadium phases or of important stresses in them. Finally, the vanadium oxide thin films exhibited significant sensory capabilities decreasing their resistance in the presence of hydrogen gas with response times in the order of a few seconds and working temperature at 40 °C. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-19T05:30:12.049143-05:
      DOI: 10.1002/pssc.201510029
       
  • Growth mechanism of planar or nanorod structured tungsten oxide thin films
           deposited via aerosol assisted chemical vapour deposition (AACVD)
    • Authors: Min Ling; Chris Blackman
      Abstract: Aerosol assisted chemical vapour deposition (AACVD) is used to deposit tungsten oxide thin films from tungsten hexacarbonyl (W(CO)6) at 339 to 358 °C on quartz substrate. The morphologies of as‐deposited thin films, which are comprised of two phases (W25O73 and W17O47), vary from planar to nanorod (NR) structures as the distance from the inlet towards the outlet of the reactor is traversed. This is related to variation of the actual temperature on the substrate surface (ΔT = 19 °C), which result in a change in growth mode due to competition between growth rate (perpendicular to substrate) and nucleation rate (parallel to substrate). When the ratio of perpendicular growth rate to growth rate contributed by nucleation is higher than 7.1, the as‐deposited tungsten oxide thin film forms as NR. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:40:11.242767-05:
      DOI: 10.1002/pssc.201510047
       
  • Intermolecular interaction between rare earth and manganese precursors in
           metalorganic chemical vapor deposition of perovskite manganite films
    • Authors: Toshihiro Nakamura
      Abstract: The gas‐phase reaction mechanism was investigated in liquid delivery metalorganic chemical vapor deposition (MOCVD) of praseodymium and lanthanum manganite films. We studied the gas‐phase behavior of praseodymium, lanthanum, and manganese precursors under actual CVD conditions by in situ infrared absorption spectroscopy. The rate of the decrease of the infrared absorbance due to Pr(DPM)3 was almost constant even if Mn(DPM)3 was added, indicating that the intermolecular interaction between Pr and Mn precursors in the gas phase is relatively weak in MOCVD of praseodymium manganite films. On the other hand, the temperature dependence of the infrared absorption indicates that the thermal decomposition of La(DPM)3 was promoted in the presence of Mn(DPM)3. The significant intermolecular interaction occurs between La and Mn precursors in the gas phase in MOCVD of lanthanum manganite films. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:40:07.260177-05:
      DOI: 10.1002/pssc.201510030
       
  • Hot‐wire vapor deposition of amorphous MoS2 thin films
    • Authors: Georgios Papadimitropoulos; Nikolaos Vourdas, A. Kontos, Maria Vasilopoulou, Dimitrios N. Kouvatsos, Nicolas Boukos, Alberto Gasparotto, Davide Barreca, Dimitrios Davazoglou
      Abstract: Amorphous, as shown by X‐ray diffraction measurements, MoS2 films (a‐MoS2) were deposited by heating a molybdenum wire at temperatures between 500 and 700 °C in H2S at 1 Torr. As shown by Scanning Electron Microscopy measurements, the morphology of samples depends significantly on the filament temperature; at low temperature samples are homogeneous and smooth, at intermediate temperatures they exhibit a granular microstructure and at high temperatures a columnar one. X‐ray photoelectron spectroscopy measurements have shown S/Mo ratios in films varying between 2.5 and 1.5 dependent on filament temperature. Films also contain oxygen at atomic contents of 8 to 12 %. As shown by XPS and Raman spectroscopy, at a filament temperature of 600 °C films are mainly composed of MoS2 also containing oxygen at an atomic ratio of 8%. Spectroscopic ellipsometry measurements made on a‐MoS2 films have shown that their band gap is of the order of 1.4 eV, slightly higher than that for the bulk crystalline material. Photoluminescence spectroscopy measurements have shown that samples exhibit a doublet of peaks at 2.8 and 3 eV blue shifted relatively to MoS2 samples composed of one or two mono‐layers. The above indicate that the electronic structure of crystalline atomic‐layer thick MoS2 is preserved in a‐MoS2 films. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:40:06.027588-05:
      DOI: 10.1002/pssc.201510031
       
  • Diamond crystals deposited from interacting jets
    • Authors: Aleksey Rebrov; Aleksey Emelyanov, Sergey Kosolobov, Ivan Yudin
      Abstract: This paper describes the advancement of hot wire or hot filament CVD methods of diamond synthesis through the use high velocity gas flow activation by multiple collisions with a lengthy hot surface instead of activation by single collisions with hot wires. The possibility of synthesis of diamond crystals from a neutral gas with a high growth rate and a future solution of engineering scaling problems promise that this method will become competitive with others. Interacting jets of hydrogen and mixture of hydrogen with methane were used to synthesize diamond crystals on a molybdenum substrate. The growth rate of crystals about 20 μm/h was attained, which is much higher than in the case of a hot filament CVD. The increase of CH4 concentration essentially increases the diamond crystal growth rate. Depending on local conditions of the interaction of jets with substrates in different points, a completely different morphology of deposit is observed: from a compact film to isolated coarse crystals mostly icosahedral form. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:40:04.666374-05:
      DOI: 10.1002/pssc.201510043
       
  • Electronic structure of threading dislocations in wurtzite GaN
    • Authors: I. Belabbas; J. Chen, G. Nouet
      Abstract: We have carried out atomistic simulations, based on density functional theory, to investigate the atomic and electronic structures of the three types of prismatic threading dislocations in hexagonal gallium nitride. Screw and mixed threading dislocations were demonstrated to introduce both deep and shallow gap states, while most of core configurations of the edge dislocation introduce solely shallow states. The higher electrical activity of both screw and mixed dislocations, compared to the edge one, is correlated with the high dispersion of their energy levels, within the GaN bandgap. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:30:13.232276-05:
      DOI: 10.1002/pssc.201400215
       
  • Impact of dopants and silicon structure dimensions on {113}‐defect
           formation during 2 MeV electron irradiation in an UHVEM
    • Authors: J. Vanhellemont; S. Anada, T. Nagase, H. Yasuda, A. Schulze, H. Bender, R. Rooyackers, A. Vandooren
      Abstract: When processing Si nanowire based Tunnel Field Effect Transistors (TFETS's), a significant reduction of B diffusion with decreasing nanowire diameter is observed and attributed to reduced transient enhanced diffusion close to the nanowire surface caused by the recombination and out‐diffusion of excess self‐interstitials. In this study, Ultra High Voltage Electron Microscopy (UHVEM) is used to study in situ the formation of self‐interstitial clusters in nanowire based TFET containing samples prepared by Focused Ion Beam (FIB) thinning. Si nanowires with diameters ranging from 40 to 500 nm are irradiated in an UHVEM using different fluxes of 2 MeV electrons at temperatures between room temperature and 375 °C. A strong dependence of defect formation on nanowire radius and on dopant concentration and type is observed. The UHVEM observations are compared with simulations based on quasi‐chemical reaction rate theory and with two dimensional dopant concentration distributions determined with high‐vacuum Scanning Spreading Resistance Microscopy (SSRM). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:30:12.095424-05:
      DOI: 10.1002/pssc.201400222
       
  • Effect of O2 flow rate on the electrochromic response of WO3 grown by
           LPCVD
    • Authors: Konstantinos Psifis; Dimitris Louloudakis, Dimitra Vernardou, Emmanuel Spanakis, George Papadimitropoulos, Dimitris Davazoglou, Nikolaos Katsarakis, Emmanuel Koudoumas
      Abstract: Tungsten trioxide coatings were grown on fluorine doped tin dioxide glass substrate at 465 oC by low pressure chemical vapor deposition. Monoclinic tungsten oxide with low crystallinity containing agglomeration of grains was obtained irrespective of the O2 flow rate utilized. It was only observed an increase of grain size to 75 from 25 nm as the O2 raised to 100 from 25 sccm. In addition, the current density was similar among the samples irrespective of the growth conditions performed. Finally, the coloration efficiency was estimated to be 83 cm2 C‐1 at 670 nm, which is higher than other grown samples using greater deposition temperatures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:30:11.06208-05:0
      DOI: 10.1002/pssc.201510004
       
  • Effect of O2 flow rate on the thermochromic performance of VO2 coatings
           grown by atmospheric pressure CVD
    • Authors: Dimitris Louloudakis; Dimitra Vernardou, Emmanouel Spanakis, Spyros Dokianakis, Marianthi Panagopoulou, Giannis Raptis, Elias Aperathitis, George Kiriakidis, Nikolaos Katsarakis, Emmanouel Koudoumas
      Abstract: This paper reports the atmospheric pressure chemical vapor deposition of vanadium oxide coatings using vanadyl (IV) acetylacetonate at 500 oC. The as‐grown samples for 0.8 L min‐1 O2 flow rate showed an (022)‐oriented single vanadium dioxide monoclinic phase of low crystallinity. The narrowest hysteresis width is observed for the particular flow rate indicating a dependency on the shape of the grown crystallites. Regarding the difference in transmittance is determined by the enhanced presence of short‐ and long‐range bond ordering of the samples. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:30:09.955649-05:
      DOI: 10.1002/pssc.201510005
       
  • Investigation of the kinetics of the chemical vapor deposition of aluminum
           from dimethylethylamine alane: experiments and computations
    • Authors: Ioannis G. Aviziotis; Thomas Duguet, Khaled Soussi, George Kokkoris, Nikolaos Cheimarios, Constantin Vahlas, Andreas G. Boudouvis
      Abstract: Experiments and computations are performed for the metalorganic chemical vapor deposition (MOCVD) of aluminum (Al) from dimethylethylamine alane (DMEAA). The deposition rate as a function of the substrate temperature and the evolution of the deposition rate along the radius of the susceptor are experimentally determined, in a vertical, warm wall MOCVD reactor operating at 10 Torr, in the temperature range 139 °C‐240 °C. Following previously published mechanism for the decomposition of DMEAA, a predictive 3D model of the process is built, based on the mass, momentum, energy and species transport equations with the aim to simulate the process. Taking into account experimental results it is demonstrated that a volumetric and a surface reaction are responsible for the deposition of Al from DMEAA. For both reactions, first order Arrhenius kinetics are implemented and the kinetic parameters are determined through fitting to the experimental data. The results show satisfactory agreement between experiments and computations for almost the whole temperature range examined. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-13T04:30:08.887113-05:
      DOI: 10.1002/pssc.201510023
       
  • Peculiarities of defect generation under injection current in LEDs based
           on A3N nanostructures
    • Authors: Natalia Shmidt; Evgeniia Shabunina, Alexander Usikov, Anton Chernyakov, Sergey Kurin, Hikki Helava, Yuri Makarov
      Abstract: It has been demonstrated that, along with well‐known mechanisms of defect generation (DG) under injection current in fabricated UV‐ and commercial blue‐LED chips based on A3N nanostructures, other defect generation mechanisms are possible in local regions. Aging experiments performed simultaneously with analysis of evolution of I‐V characteristics at U < 2 V and spectral noise density dependences on current density, revealed DG with participation of multi‐phonon recombination of carriers in an extended defect system and local regions of random alloy fluctuations enriched by metallic atoms (Ga or In). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-11T06:10:32.205478-05:
      DOI: 10.1002/pssc.201400218
       
  • EBIC investigations of dislocations in ELOG GaN
    • Authors: E. B. Yakimov; A. Y. Polyakov
      Abstract: Dislocations in the ELOG n‐GaN films have been studied by the Electron Beam Induced Current (EBIC) method. The effect of dopant concentration and diffusion length values on the dislocation EBIC profile is revealed. It is shown that the width of dislocation image in the EBIC mode decreases with a diffusion length decrease and the dopant concentration increase. In the crystals with the submicron diffusion length the individual dislocations can be separated in the EBIC images up to the dislocation densities higher that 109cm‐2. The radius of dislocation related defect cylinder was found to increase with the dopant concentration decreasing that could be explained under an assumption that dislocations in GaN are charged. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-11T06:10:31.257827-05:
      DOI: 10.1002/pssc.201400220
       
  • About dislocation and oxygen related luminescence of Si around 0.8 eV
    • Authors: M. Kittler; T. Arguirov, M. Reiche, C. Krause, D. Mankovics
      Abstract: In conjunction with the two‐level model the temperature behaviour of the dislocation‐related D1‐peak follows the T‐behaviour of the band gap. Based on luminescence observations in our laboratory and on literature data we propose a ∼30 meV wide domain of the D1 peak. Altogether, the D1‐peak position ranges between about 0.76 eV at 300 K and nearly 0.84 eV at a few K. It was shown that the energetic shift for a certain temperature is caused by external electric fields, by excitation level, that affects the intrinsic dislocation field, and by elastic stress. The luminescence of oxygen‐related defects / precipitates might be described by a line at ∼ 0.77 eV (P‐line) that does not depend on temperature. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-11T06:10:30.379016-05:
      DOI: 10.1002/pssc.201400231
       
  • Materials characterization and device analysis for evaluation of
           semiconductor processes by highly‐sophisticated photoelastic stress
           measurement technique
    • Authors: Martin Herms; Matthias Wagner, Alexander Molchanov, Pinyen Lin, Ingrid De Wolf, Ming Zhao
      Abstract: SIRD (Scanning Infrared Depolarization Imager) and SIREX (Scanning Infrared Stress Explorer) are measurement systems to evaluate and visualize the stress distribution in semiconductor materials and devices. Some main fields of application are crystal growth, high temperature processing of silicon wafers as well as the 3D‐structuring of silicon‐based microelectronic devices. The used strategies of measurement are different. SIRD and SIREX are equipped with versatile software packages that allow to separate defect‐related stress states of interest, for instance slip‐lines in GaN‐overgrown silicon. Micro‐holes fabricated for wafer marking and 3D TSV (through silicon vias) structures have been analyzed with micrometer resolution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-11T06:10:29.508895-05:
      DOI: 10.1002/pssc.201400356
       
  • A calculation method of deposition profiles in chemical vapor deposition
           reactors using bio‐inspired algorithms
    • Authors: Takahiro Takahashi; Taeka Inagaki, Shingo Nariai, Junichi Kodama, Masamoto Arakawa, Yoshinori Ema
      Abstract: Estimating the predicted results of experimental data by a simulator is one of the most important processes in deciding the performance of the automatic modeling system of reaction mechanisms in chemical vapor deposition (CVD). Therefore, we developed a novel calculation method, in which robust and accurate calculations along with reduced computing cost were achieved, to reproduce deposition profiles in the specific types of reactors. In order to improve the performance of the calculation method, we developed the method by use of the novel optimization algorithms, which are biologically inspired. We adopted real‐coded genetic algorithms (GAs) and artificial bee colony (ABC) as the bio‐inspired algorithms (BIAs). Boundary value problems for estimating diffusion‐reaction equations by iterations of numerical integrations were changed into problems of finding the linear combinations consisted of a few “basis functions”, which are ideally inherent in the reactors. The coefficients of the linear combinations were optimized by the BIAs. We demonstrate the improved performance of the simulator by the BIAs using the batch‐type reactor with round‐shaped substrates. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:23:55.696331-05:
      DOI: 10.1002/pssc.201510056
       
  • Gaseous ternary chromium‐aluminium complexes as precursor for
           chemical vapour deposition
    • Authors: Mario Lessiak; Roland Haubner, Reinhard Pitonak, Arno Köpf, Ronald Weissenbacher
      Abstract: Research on high‐performance CVD coatings follows the target to increased hardness and oxidation resistance. Such coatings and coating systems are required for machining tools to optimize the manufacturing parameters for new materials and new processes. The use of chromium‐containing coatings is requested because of its feature to increase the corrosion resistance. The production of various chromium‐containing coatings is already shown by PVD, but for industrial scale CVD processes there are problems with the chromium precursors. Especially the chromium chlorides have a low vapour pressure and therefore high temperatures are needed for evaporation. To overcome the disadvantages of CrCl3 the relatively good evaporation of halide complexes was reported, showing potential for new CVD processes. Numerous metal compounds form gaseous complexes with Aluminium chloride but also Cr. Based on this characteristic the transport reaction of CrCl2/Al2Cl6 as chromium tetrachloraluminate is investigated. The focus of this work lies in the preparation of the chromium precursors as well as in the optimization of the transport reaction which required various changes in the conventional experimental CVD‐setup. To measure the amount of transported chromium the gas phase was condensed and their Cr‐content was analyzed. For the CVD deposition of Cr containing coatings, this precursor gas flow can be used directly. Further the interaction between aluminum chloride and the chromium precursor, different process parameters, as well as existing difficulties regarding the transport reaction are discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:37.004106-05:
      DOI: 10.1002/pssc.201510007
       
  • Kinetic study of MOCVD of NiO films from bis‐(ethylcyclopentadienyl)
           nickel
    • Authors: A. S. Kondrateva; M. Mishin, A. Shakhmin, M. Baryshnikova, S. E. Alexandrov
      Abstract: NiO films were grown by metal‐organic chemical vapor deposition (MOCVD) using bis‐(ethylcyclopentadienyl) nickel [(EtCp)2Ni] and oxygen or ozone as precursors. The kinetic regularities of MOCVD processes were experimentally studied in the deposition temperature range 600‐820 K for the reaction systems: (EtCp)2Ni–O2–Ar and (EtCp)2Ni–O3–O2–Ar. The results obtained show that the deposition processes in the temperature range 600‐700 K are controlled by kinetics and the value of activation energy of the processes is 80±5 kJ·mol−1 in both cases. The growth process in the temperature region 700–840 K is controlled by mass transport. An introduction of ozone in the reaction gas phase led to nearly twofold decrease of deposition rate probably because of homogeneous reactions with (EtCp)2Ni. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:35.98742-05:0
      DOI: 10.1002/pssc.201510014
       
  • CVD synthesis and catalytic combustion application of chromium oxide films
    • Authors: Jing Liang; Guan‐Fu Pan, Shi‐Bin Fan, Wei‐Liang Cheng, Zhen‐Yu Tian
      Abstract: Chromiumoxide (Cr2O3) thin films were controllably synthesized by pulsed‐spray evaporation chemical vapor deposition (PSE‐CVD) for deep oxidation of propene. The effect of substrate temperature on the growth kinetics and morphology of the films was investigated. The prepared samples were comprehensively characterized with respect to structure, morphology and surface composition with XRD, SEM and XPS, respectively. An in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was involved to reveal the surface mechanism occurred on Cr2O3. The growth rate exhibited a linear behavior when the temperature increase from 300 to 450 °C. The structural analysis indicated that a pure phase of Cr2O3 was obtained at 425 °C. The catalytic tests showed that Cr2O3 films prepared on flexible substrates exhibited advantages for the catalytic oxidation of C3H6. Based on the DRIFTS observations, the Langmuir‐Hinshelwood (L‐H) mechanism was proposed for C3H6 over Cr2O3 films. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:35.103864-05:
      DOI: 10.1002/pssc.201510019
       
  • CVD nanographite films covered by ALD metal oxides: structural and field
           emission properties
    • Authors: Rinat R. Ismagilov; Feruza T. Tuyakova, Victor I. Kleshch, Ekaterina A. Obraztsova, Alexander N. Obraztsov
      Abstract: Nanographite films produced by direct current plasma enhanced chemical vapour deposition technique were covered by metal oxides TiO2 and Al2O3 using atomic layer deposition. Nanographite films are composed of few‐layer graphene nanowalls and nanoscrolls, which are mostly oriented perpendicular to the silicon substrate surface. The nanographite and nanographite‐metal oxide composite film materials, with oxide layer thickness between 50 nm and 250 nm, were characterized by scanning electron microscopy, energy dispersive X‐ray analysis, thermal gravimetric analysis, and Raman spectroscopy. We demonstrate that the metal oxide deposit homogenously covers graphene nanowalls and forms individual spherical particles on the surface of needle‐like nanoscrolls. Field emission properties of the samples were measured in a flat vacuum diode configuration. It was found that the metal oxide layers thinner than 200 nm do not significantly affect the field emission characteristics of the nanographite. At the same time, metal oxides form a passivation shell which may improve the nanographite film performance as cold cathode in vacuum electronic devices. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:34.09799-05:0
      DOI: 10.1002/pssc.201510022
       
  • Effect of substrate temperature on initiated plasma enhanced chemical
           vapor deposition of PHEMA thin films
    • Authors: Mehmet Gürsoy; Mustafa Karaman
      Abstract: Poly(2‐hydroxyethyl methacrylate) (PHEMA) thin films were deposited on silicon wafers by initiated plasma enhanced chemical vapour deposition (i‐PECVD) method at different substrate temperatures. Di tert‐butyl peroxide (TBPO) was used as an initiator, and all deposition experiments were performed at 3:1 monomer to initiator flow ratio. Deposition rates up to 44 nm/min were observed at relatively low plasma power depending on the deposition conditions. The high deposition rates at low plasma powers were attributed to the usage of the initiator. Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS) analyses of the deposits indicated very high retention of hydroxyl and carbonyl functionalities especially for the polymers deposited at low plasma powers. Water contact angle measurements were carried out to determine the wettability of as‐deposited PHEMA surfaces. This study indicated that the substrate temperature is an important parameter determining the polymerization rate. Being a dry, low‐cost, reliable and environmentally friendly process, the i‐PECVD technique developed in this study can be used to deposit other functional polymers. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:33.227986-05:
      DOI: 10.1002/pssc.201510034
       
  • Time‐scale analysis of atomic layer deposition processes: Predicting
           the transition from mass‐transfer to kinetically limited regimes
    • Authors: Raymond A. Adomaitis
      Abstract: The relative rates of adsorption and irreversible reaction are modeled for a prototypical atomic layer deposition (ALD) system. Surface species balance modeling equations are processed through a reaction factorization procedure to eliminate redundant dynamic modes. The resulting singular perturbation problem then is used to develop a criterion that distinguishes between mass‐transfer and kinetically‐limited deposition regimes for this dynamic process. Detailed simulations of a TMA/water alumina ALD process are used to evaluate our analysis approach and to demonstrate the dominance of mass‐transfer limitations for this system during both precursor exposure periods. Our analysis shows the increasing likelihood of encountering mass‐transfer limitations at reduced temperatures, a finding opposite of what might be expected. We find that the ALD dynamics evolve on a manifold defined by the balancing of adsorption and irreversible reaction rates, further reducing the dynamic dimension of the deposition dynamics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:32.139295-05:
      DOI: 10.1002/pssc.201510048
       
  • The automatic experimental design for modeling the reaction mechanisms of
           chemical vapor deposition processes
    • Authors: Takahiro Takahashi; Yoshinori Ema
      Abstract: The identification of an appropriate reaction model (reaction mechanism) that indicates the reaction paths from source gases to films is one of the most important facets for developing chemical vapor deposition (CVD) processes. Previously, we developed a system that automatically identifies the kinetic models of reaction mechanisms involved in experimental results by the CVD processes using genetic algorithms (GAs). However, in order to automate the entire process of CVD development, it is necessary to automate the other processes associated with the reaction‐modeling process. Therefore, in this study, we proposed the method to automate the experimental design to determine more appropriate the reaction models. In addition, we developed the automatic system to design the experiments for the models. We demonstrated the feasibility and validity of the method using a simplified and synthetic CVD process. The system automatically and appropriately designed the experiments from the information of the reaction model candidates without using the knowledge of reaction engineering directly. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:31.242865-05:
      DOI: 10.1002/pssc.201510052
       
  • Ab‐initio study of ferromagnetism in Mn‐doped ZnSnAs2
    • Authors: Vusala Jafarova; Suma Huseynova, Guseyn Orudzhev, Naotaka Uchitomi, Kazuki Wakita, Nazim Mamedov
      Abstract: The electronic and magnetic properties of pure as well as Mn‐doped chalcopyrite semiconductor ZnSnAs2 were studied by the DFT+U ab initio method within the spin generalized gradient approximation. The band structure and DOS calculations resulted in a direct gap scenario for semiconducting ZnSnAs2. The energy gap of 0.34 eV occurs at the center of the Brillouin zone and linearly increases with increasing Mn concentration x at a rate of 2.05 eV for x < 0.03. The total energy calculations for a number of supercells showed that a ferromagnetic rather than antiferromagnetic ordering is favorable in Mn‐doped ZnSnAs2 when Mn replaced Sn. The energy deficient substitution of Zn by Mn led to the antiferromagnetic ordering. The magnetic moment per Mn atom, together with contribution of each atom into the total moment of ZnSnAs2: Mn was determined. The contributions from Mn and As are dominant but have opposite signs. Besides, the As atoms chemically bounded to Mn dopant were found to be most contributive. At last it was shown that the vacancies such as V(Zn), V(Sn), and V(As) affect the magnetic properties and may even strengthen the magnetization of Mn‐doped ZnSnAs2. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:29.991945-05:
      DOI: 10.1002/pssc.201400355
       
  • Luminescent property and mechanism of ZnAl2O4 ultraviolet emitting
           phosphor
    • Authors: Takeaki Ishinaga; Taku Iguchi, Hiroko Kominami, Kazuhiko Hara, Mamoru Kitaura, Akimasa Ohnishi
      Abstract: ZnAl2O4 ultraviolet (UV) emitting phosphor has been studied for next‐generation ultraviolet emission device. In this work, to investigate the mechanism of ZnAl2O4, the phosphor was evaluated and analyzed using various methods. It is thought that the optimum ratio of source materials to obtain the single phase of ZnAl2O4 is 0.975. UV emission peak of ZnAl2O4 was changed from around 250 nm to 270 nm and the absorption edge was shifted to lower energy as increase the ratio of source materials. It is thought that bandgap of ZnAl2O4 became narrower as increase the ratio of source materials. From the results of annealing in active carbon, it became clear that the UV emission from ZnAl2O4 was caused oxygen vacancy. Additionally, from the results of sterilization examination, it is thought that the properties of ZnAl2O4 are promising for using it as candidate for sterilization. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:28.817776-05:
      DOI: 10.1002/pssc.201400317
       
  • Growth of β‐gallium oxide films and nanostructures by
           atmospheric‐ pressure CVD using gallium and water as source
           materials
    • Authors: Tomoaki Terasako; Hikaru Ichinotani, Masakazu Yagi
      Abstract: Films and nanostructures of β‐Ga2O3 were successfully grown by atmospheric‐pressure CVD (AP‐CVD) using metal Ga and H2O as source materials. It was confirmed that highly (‐201) oriented polycrystalline β‐Ga2O3 films can be obtained on c ‐plane sapphire (c ‐Al2O3) substrates by optimizing growth temperature (Tg) and source supply ratio of H2O to Ga. The optical gap energy of the β‐Ga2O3 film with a relatively flat surface was estimated to be ∼4.9 eV. Photoluminescence (PL) measurements for the β‐Ga2O3 films revealed the existence of at least three emission bands with their peaks at ∼370 nm, ∼440 nm and ∼520 nm. Various shapes of quasi 1D nanostructures, such as nanowires (NWs), nanorods (NRs), tapered NRs and nanobelts (NBs), were obtained on the c ‐Al2O3 substrates coated with the Au films by utilizing vapour‐liquid‐solid (VLS) growth mechanism. The diversity of the quasi 1D nanostructures is probably due to the contribution of vapour‐solid (VS) growth mechanism and/or the coalescence between the neighbouring Au metal particles before initiating the NW (or NR) growth. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-07T03:13:27.86977-05:0
      DOI: 10.1002/pssc.201510012
       
  • Bismuth‐doped Cu(In,Ga)Se2 absorber prepared by multi‐layer
           precursor method and its solar cell
    • Authors: Jakapan Chantana; Daisuke Hironiwa, Taichi Watanabe, Seiki Teraji, Kazunori Kawamura, Takashi Minemoto
      Abstract: Bismuth (Bi)‐doped Cu(In,Ga)Se2 (CIGS) films were prepared by the so‐called “multi‐layer precursor method”, obtained by depositing them onto Bi layers with various thicknesses on Mo‐coated soda‐lime glass (SLG) substrates. Material composition (Cu, In, Ga, and Se) profiles of the CIGS films are almost identical, whereas sodium (Na) is reduced, when Bi thickness is increased. Moreover, the incorporation of Bi into the CIGS film is enhanced with thicker Bi layer. With Bi thickness from 0 to 70 nm, the 2.4‐μm‐thick CIGS absorbers demonstrate the increase in CIGS grain size, carrier lifetime, and carrier concentration, thus improving their cell performances, especially open‐circuit voltage (VOC). With further increase in Bi thickness of above 70 nm, the CIGS films show the deterioration of CIGS film quality owing to the formation of Bi compounds such as Bi, BiSe, and Bi4Se3. Consequently, Bi‐doped CIGS absorber with thickness of 2.4 μm, prepared with the 70‐nm‐thick Bi layer on Mo‐coated SLG substrate, gives rise to the improvement of photovoltaic performances, especially VOC. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T08:10:39.569338-05:
      DOI: 10.1002/pssc.201400239
       
  • Thin film growth of Cd1‐xZnxTe and its application to X‐ray
           sensor
    • Authors: K. Mochizuki; J. Takahashi, N. Nakamura
      Abstract: Cd1‐xZnxTe (x∼0.5) thin films with less than 300μm are grown on ITO/glass substrate by Hot‐wall and PVT methods, one of the sublimation methods. In order to obtain the films with high resistivity and good quality for X‐ray sensor, three attempts have been tried in the experiments. The one is stoichiometry control of CZT (x = 0.04) films, which were grown under controlled Cd vapor pressure. The second is excess chlorine doping to the films (x = 0.04) by controlling CdCl2 vapor pressure during growth process. The third is to change composition x = 0.04‐0.50, which increases band gap. Through these methods, best films with good X‐ray response was obtained for the third case of the films with the composition x = 0.20. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T08:10:38.736196-05:
      DOI: 10.1002/pssc.201400264
       
  • Effect of preheating time on uniformity of electrodeposited Cu2ZnSnS4 thin
           films studied by carrier lifetime and photoluminescence measurements
    • Authors: T. Hamada; A. Fukuyama, F. Jiang, S. Ikeda, T. Ikari
      Abstract: Cu2ZnSnS4 (CZTS) is paid attention to the low‐cost and nontoxic solar cell material. In this study, CZTS thin film was deposited by using an electrodeposition technique followed by a sulfurization after preheating the deposited metallic precursor layer. We investigated the film properties of CZTS thin films for understanding the effect of preheating time on the photovoltaic properties such as carrier lifetime and recombination mechanism by using a microwave photoconductivity decay (μ‐PCD) and a photoluminescence (PL) measurement. The results of the μ‐PCD measurements showed that carrier lifetime increased with increasing the preheating time and longer carrier lifetime was observed in a part of deposited thin film. The PL measurements showed the peak energy shift to lower energy region by a surface position of the sample preheated for 150 min. We found the CZTS crystal quality improved but the homogeneity worsened with increasing the preheating time. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T08:10:37.428163-05:
      DOI: 10.1002/pssc.201400283
       
  • Preparation and characterization of Cu2Six Sn1‐xS3
    • Authors: Kotoba Toyonaga; Hideaki Araki
      Abstract: Cu2SnS3 is a promising compound for use as an absorber layer in thin film solar cells because it is made up of low‐cost and abundant elements, and has a high optical absorption coefficient. However, the band gap energy of monoclinic Cu2SnS3 is less than the value required for absorber layers in single‐junction solar cells. On the other hand, the band gap energy of Cu2SiS3 was reported to be approximately 2.5 eV, which is sufficiently large for this purpose. Therefore, in the present study, an attempt was made to synthesize Cu2Six Sn1‐xS3, which is a solid solution between Cu2SnS3 and Cu2SiS3. In X‐ray diffraction patterns from the synthesized compounds, the diffraction peaks were found to shift to higher 2θ values with increasing x, indicating a decrease in the lattice constants. In addition, the estimated band gap energy increased from 0.85 to 2.56 eV with increasing x. Cu2Six Sn1‐xS3 is therefore a potential candidate for use as the absorber layer in thin film solar cells because its band gap energy can be adjusted simply by varying its composition. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:45.917093-05:
      DOI: 10.1002/pssc.201400296
       
  • Growth and characterization of Ga doped ZnSnAs2 thin films on InP
           substrates
    • Authors: Takahiro Kato; Takashi Uchiyama, Hideyuki Toyota, Naotaka Uchitomi
      Abstract: We have grown Ga doped ZnSnAs2 thin films on InP substrates using all‐solid source MBE technique. Using the optimum substrate temperature of 340 ºC and Zn:Sn:As4 beam equivalent pressure ratio (BEPR) of 24:1:52, samples were prepared with different Ga concentration achieved by changing the Ga flux. Compositional analysis was performed using electron microprobe microanalysis (EMPA). We found that Ga concentration on the cation sites is 20.9% and 8.7%. XRD patterns of Ga doped samples showed only assignable to ZnSnAs2:Ga and InP substrate. The lattice constant decreases linearly from 0.5862 to 0.5829 nm with decreasing Ga concentration. The observed concentration dependence indicates that the lattice constant of the thin films can be controlled by Ga doping concentration. Hall coefficient and resistivity of Ga 8.7 % doped sample can be well explained by the impurity band model. We were able to resolve the experimentally obtained carrier concentration pexp and mobility μexp into valence band carrier concentration pv with mobility μv and acceptor band carrier concentration pa with mobility μa. The computed apparent values papp and μapp are in good agreement with pexp and μexp, respectively. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:44.528067-05:
      DOI: 10.1002/pssc.201400295
       
  • Fabrication of 5.2% efficient Cu2ZnSn(S,Se)4 solar cells using
           DC‐sputtered metal precursors followed by sulfo‐selenization
    • Authors: Han Sung Yang; Ganesh Agawane, Seung Wook Shin, Sharadrao Vanalakar, Woo Lim Jung, Jin Hyeok Kim
      Abstract: In this study, we report Cu2ZnSn(S,Se)4 (CZTSSe) thin films synthesized by using a rapid thermal annealing process of direct current sputtered precursors under a sulfur and selenium atmosphere. X‐ray diffraction and Raman spectroscopy investigations showed formation of CZTSSe absorber layer without any secondary phase. X‐ray fluorescence spectroscopy showed a stoichiometric absorber layer has been formed which is suitable for use in solar cells. The best thin film solar cell of CZTSSe showed a photovoltaic performance of 5.2% efficiency (Voc: 585.0 mV, Jsc: 17.0 mA/cm2 and FF: 52.0%). This is the highest efficiency reported for CZTSSe prepared from sputtered Cu/Zn/Sn precursors followed by sulfo‐selenization using powder sources. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:43.603596-05:
      DOI: 10.1002/pssc.201400287
       
  • Control of extended defects in cast multicrystalline silicon using
           polycrystalline template
    • Authors: Ronit R. Prakash; Karolin Jiptner, Jun Chen, Yoshiji Miyamura, Hirofumi Harada, Takashi Sekiguchi
      Abstract: Extended defects were controlled using polycrystalline silicon as a template for cast‐growth of multicrystalline silicon. At the initial stage of growth, small randomly oriented grains with a high density of random type grain boundaries were obtained. With growth, the grain size increased and the fraction of random grain boundaries decreased. Electrical activity of defects was investigated and it was found that with growth, network of small angle grain boundaries became the most electrically active defects. This network of small angle grain boundaries were found to have a tilt angle less than 3° and were mainly found in elongating grains. The density of these highly electrically active grain boundaries increased with growth. This can be attributed to propagation and agglomeration of dislocations into small angle grain boundaries. The high density of random grain boundaries in this ingot may suppress dislocation propagation between grains, however they do not intersect elongating grains enabling dislocation propagation in elongated grains. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-24T03:30:05.844509-05:
      DOI: 10.1002/pssc.201400299
       
  • Modeling micromechanical response to thermal history in bulk grown
           aluminum nitride
    • Authors: Payman Karvani; Antoinette M. Maniatty
      Abstract: A thermal‐elastic‐viscoplastic model suitable for modeling aluminum nitride (AlN) during crystal growth is presented. A crystal plasticity model that considers slip along crystallographic slip systems and the evolution of mobile and immobile dislocations on the prismatic and basal slip systems is developed. The model has been implemented into a finite element framework, and a sublimation growth process is modeled to demonstrate the model capability. The dislocation density, which characterizes the crystal quality, and the maximum tensile stress on the cleavage planes (m ‐planes), which leads to cracking, are computed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-18T08:10:22.937267-05:
      DOI: 10.1002/pssc.201100189
       
  • Contents: Phys. Status Solidi C 6/2015
    • Pages: 475 - 483
      PubDate: 2015-06-18T05:14:57.709555-05:
      DOI: 10.1002/pssc.201570088
       
  • Ternary and Multinary Compounds
    • Authors: Nozomu Tsuboi; Kazuki Wakita, Akira Yamada, Sho Shirakata, Takahiro Wada, Shigeru Niki, Mitsuru Imaizumi, Kazuhiko Hara, Naotaka Uchitomi
      Pages: 485 - 488
      Abstract: The 19th International Conference on Ternary and Multinary Compounds (ICTMC‐19) was held on 1–5 September 2014 at Toki Messe, Niigata, Japan. This conference, part of the series of conferences that began in 1973 in Bath, was held traditionally as an interdisciplinary forum for the exchange of information and experience in the exciting field of materials science of ternary and multinary compounds. It was then held in Strasbourg (1975), Edinburgh (1977), Tokyo (1980), Cagliari (1982), Caracas (1984), Snowmass (1986), Kishinev (1990), Yokohama (1993), Stuttgart (1995), Salford (1997), Hsin‐chu (2000), Paris (2002), Denver (2004), Kyoto (2006), Berlin (2008), Baku (2010), and Salzburg (2012). The conference brought together researchers for the discussion of the latest developments and achievements in the field of these complex materials. The scientific program included two plenary talks, 20 invited talks, 13 symposium talks, 50 oral presentations, and 112 poster presentations from the following 15 countries: Japan, Taiwan, Azerbaijan, Germany, Korea, Thailand, USA, Philippines, France, Belgium, China, Mexico, Moldova, Turkey, and UK. Of the papers, 95 are included in the present proceedings volumes of physica status solidi. The Conference covered physics, chemistry, materials science, device engineering, and the growth and theory of various ternary and multinary compounds: chalcopyrite‐type (I–III–VI2, II–IV–V2), kesterite‐type (I2–II–IV–VI4), sphalerite‐type and wurtzite‐type (III–V, II–VI, etc.), perovskite‐type, skutterudite‐type, complex‐oxides, complex‐nitrides, and so on. Three symposiums in the conference were focused on new photovoltaic materials superior to CIGS, advanced characterization of solar cells, and mulitinary materials in the next generation. The Program Committee picked up three young members as the winners of the “Best Young Scientists Award” for their excellent presentations. The winners are Galina Gurieva, Ayaka Kanai, and Tsuyoshi Maeda. The Guest Editors wish to express their gratitude to the members of the International Advisor Committee, the Program Committee, the sponsors, the Japanese Professional Group of Multinary Compounds and Solar Cells in the Japanese Society of Applied Physics, and thank all those who have contributed to this conference for their support and advice. We are very grateful to the referees for their contributions during the editorial process. The next anniversary conference of ICTMC‐20 will be held in Germany, chaired by Prof. Roland Scheer. We convey our best wishes to the organizers for a successful meeting. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-06-18T05:14:50.936499-05:
      DOI: 10.1002/pssc.201570089
       
  • Fundamentals and R&D status of III‐V compound solar cells and
           materials
    • Authors: Masafumi Yamaguchi
      Pages: 489 - 499
      Abstract: The III‐V compound multi‐junction solar cells have high efficiency potential of more than 50% due to wide photo response, while limiting efficiencies of single‐junction solar cells are 31‐32%. In order to realize high efficiency III‐V compound multi‐junction (MJ) solar cells, understanding and controlling imperfections (defects) are very important. This paper reviews fundamentals for major losses of III‐V compound materials and solar cells, key issues for super high‐efficiency MJ solar cells and recent R&D status of III‐V compound MJ solar cells. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:09.97663-05:0
      DOI: 10.1002/pssc.201400216
       
  • A mild hydrothermal route to synthesis of CZTS nanoparticle inks for solar
           cell applications
    • Authors: S. A. Vanalakar; G. L. Agwane, M. G. Gang, P. S. Patil, J. H. Kim, J. Y. Kim
      Pages: 500 - 503
      Abstract: Cu2ZnSnS4 (CZTS) is a promising thin film absorber material for low cost solar cell applications. Its absorption coefficient (∼ 104 cm‐1), crystal structure and band gap energies (∼1.5 eV) are similar to those of Cu(In,Ga)Se2 (CIGS), one of the most studied and flourishing thin film solar cell absorber materials. However, unlike CIGS, which requires the expensive and rare elements; In and Ga, CZTS is composed of reasonably priced and abundant elements like Zn and Sn. In the present investigation, kesterite CZTS nanoparticle inks were obtained by a hydrothermal process using Cu, Zn and Sn chlorides, and Na sulfide. The synthesized CZTS nanoparticles were characterized using optical absorption, X‐ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), micro‐Raman spectroscopy, high‐resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS). The optical and morphological properties demonstrated that the prepared nanoparticles have strong absorption in 300−550 nm range with band gap energy of 1.55 eV with an average particle size of 20 nm. The X‐ray and micro‐Raman analysis revealed that the synthesized CZTS nanoparticles have the phase pure kesterite structure. We believe that our synthetic method will be helpful for low‐cost and efficient thin film photovoltaic technology. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:05.46824-05:0
      DOI: 10.1002/pssc.201400261
       
  • Fabrication of transparent CuxZnyS/ZnS heterojunction diodes by
           photochemical deposition
    • Authors: Masaya Ichimura; Yosuke Maeda
      Pages: 504 - 507
      Abstract: A CuxZnyS/ZnS transparent pn heterostructure was successfully fabricated by the photochemical deposition (PCD) from aqueous solutions. In PCD, the substrate was immersed in the solution to a depth of about 2‐3 mm from solution surface, and irradiated with the light of an ultra‐high‐pressure mercury arc‐lamp through a lens. The growth solution of CuxZnyS contained 5 mM CuSO4, 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. The growth solution of ZnS contained 1 mM ZnSO4, 600 mM Na2S2O3, and 3 mM Na2SO3. p‐type conduction of CuxZnyS and n‐type conduction of ZnS were confirmed by the photoelectrochemical measurement. Both the films had high optical transmission (>70%) in the visible range. The CuxZnyS/annealed‐ZnS heterostructure showed rectification properties and photoresponse to AM1.5 irradiation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:15.450535-05:
      DOI: 10.1002/pssc.201400229
       
  • The growth of AgGaTe2 layers on glass substrates with Ag2Te buffer layer
           by closed space sublimation method
    • Authors: Aya Uruno; Ayaka Usui, Yuji Takeda, Tomohiro Inoue, Masakazu Kobayashi
      Pages: 508 - 511
      Abstract: The AgGaTe2 layer growth was performed by the closed space sublimation method on the Mo/glass substrate. The Ag2Te buffer layer was inserted between AgGaTe2 and Mo layers, to improve the quality of grown layers. Crystallographic properties were analyzed by x‐ray diffraction (XRD), and the surface morphologies were analyzed by scanning electron microscopy (SEM). The Ag2Te layer grown on the Mo/glass exhibited a membrane filter structure from the SEM observation. XRD spectra of layers grown with and without the buffer layer were compared. The AgGaTe2 layer with the Ag2Te buffer layer exhibited peaks originating from AgGaTe2, and a very strong diffraction peak of 112 was observed. On the other hand, it was cleared that the layer grown without the buffer layer exhibited no strong peaks associated with AgGaTe2, but Ga‐Te compounds. From this, crystallographic properties of the AgGaTe2 layer were drastically improved by the insertion of the Ag2Te buffer layer. Moreover, the surface morphology exhibited a smooth surface when the Ag2Te buffer layer was inserted. The nucleation site density of AgGaTe2 was probably increased since the membrane filter structure exhibited numbers of kinks at the edge. Chemical reaction between Ga and Mo was also eliminated. It was cleared that the insertion of the buffer layer and its surface morphology were an important parameter to grow high quality AgGaTe2 layers. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:28.403448-05:
      DOI: 10.1002/pssc.201400267
       
  • Low‐temperature heteroepitaxial growth of InAlAs layers on
           ZnSnAs2/InP(001)
    • Authors: Hiroto Oomae; Akiko Suzuki, Hideyuki Toyota, Shin'ichi Nakamura, Naotaka Uchitomi
      Pages: 516 - 519
      Abstract: We studied the epitaxial growth of InAlAs on ZnSnAs2 thin films to establish magnetic heterostructures involving ferromagnetic Mn‐doped ZnSnAs2 (ZnSnAs2:Mn) thin films. These heterostructures were successfully grown at temperatures around 300 °C to maintain room‐temperature ferromagnetism in ZnSnAs2:Mn. Reflection high‐energy electron diffraction, X‐ray diffraction measurements and cross‐sectional transmission electron microscopy revealed that the InAlAs layers were pseudomorphically lattice‐matched with ZnSnAs2, even at the low temperature of 300 °C. We attempted to prepare magnetic quantum well structures from the InAlAs/ZnSnAs2:Mn magnetic multilayer structure. We found that InAlAs layers heteroepitaxially grown on ZnSnAs2 and ferromagnetic ZnSnAs2:Mn films are suitable for preparing InP‐based magnetic semiconductor quantum structures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:18.206596-05:
      DOI: 10.1002/pssc.201400246
       
  • Bulk crystal growth and characterization of ZnSnP2 compound semiconductor
           by flux method
    • Authors: Shigeru Nakatsuka; Hiroshi Nakamoto, Yoshitaro Nose, Tetsuya Uda, Yasuharu Shirai
      Pages: 520 - 523
      Abstract: ZnSnP2 is a promising candidate for solar absorber materials from the viewpoint of high absorption and earth‐abundant constitution elements. In this paper, we fabricated ZnSnP2 crystals by flux method based on the phase diagram of Sn‐ZnP2 pseudo‐binary system and investigated their properties for an application to photovoltaics. The crystal growth experiments with the cooling rate of 0.7 and 12 °C/h were carried out and we successfully obtained ZnSnP2 crystals with the diameter of 8mm and the thickness of a few mm by a slow cooling rate. The structure of grown crystals studied by X‐ray diffraction was indicated to be chalcopyrite‐type ZnSnP2. In addition, the decrease of the degree of order was observed with the increase of cooling rate. The lattice constants of a and c axes are 5.649 and 11.295 Å, respectively. The composition of grown crystals is a near stoichiometric ratio of ZnSnP2 by EDX analysis. The bandgaps of ZnSnP2 crystals obtained by cooling rate of 0.7 and 12 °C/h were estimated to be 1.61 and 1.48 eV, respectively, which is caused by the difference of the degree of order. The hall‐resistivity measurement showed that ZnSnP2 crystals with a slow cooling rate has a p‐type conduction. The resistivity, the hole concentration and the mobility are 10∼70 Ωcm, 6·1016∼2·1017 cm‐3, and 1∼3 cm2V‐1s‐1. The obtained properties are suitable for an absorber of photovoltaics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:12.061845-05:
      DOI: 10.1002/pssc.201400291
       
  • Effect of arsenic cracking on In incorporation into MBE‐grown InGaAs
           layer
    • Authors: Hiromu Iha; Yujiro Hirota, Masatsugu Yamauchi, Nao Yamamoto, Takahiro Maruyama, Shigeya Naritsuka
      Pages: 524 - 527
      Abstract: The effect of arsenic cracking on In incorporation in MBE‐grown InGaAs selective growth was systematically studied with changing the cracking cell temperature. Incorporation of In was greatly enhanced by the use of As2 molecular beam during the selective growth at 600 °C. On the other hand, almost no In was incorporated into the grown layer by the use of a conventional As4 molecular beam. The relation between InAs mole fraction and the cracking cell temperature was found to monotonously increase with the cracking cell temperature. It is probably because the ratio of As2 molecules increases with the cracking cell temperature. Not only at 600 °C but also at 580 °C, a selective growth was also successfully performed using As2 molecular beam by the formation of the “denuded zone”, with the InAs mole fraction of 10%. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:15.94053-05:0
      DOI: 10.1002/pssc.201400286
       
  • Deposition of Cl‐doped CdTe polycrystalline films by
           close‐spaced sublimation
    • Authors: Tamotsu Okamoto; Kohei Takahashi, Sho Akiba, Nao Yasuda, Satoshi Tokuda, Hiroyuki Kishihara, Akina Ichioka, Takahiro Doki, Toshiyuki Sato
      Pages: 532 - 535
      Abstract: The effects of Cl‐doping on the CdTe layers by the close‐spaced sublimation (CSS) deposition were investigated. Cl‐doped CdTe polycrystalline films were deposited on graphite substrates by CSS method using a mixture of CdTe and CdCl2 powder as a source. In X‐ray diffraction (XRD) patterns of the obtained films with various deposition times, many diffraction peaks other than CdTe peaks were observed in the deposition times lower than 10 min. These diffraction peaks were probably due to the formation of chlorides of Cd, Te and C, such as CdCl2, TeCl4, Te3Cl2 and C10Cl8. X‐ray fluorescence (XRF) and secondary ion mass spectrometry (SIMS) analyses revealed that a large amount of chlorine was contained in the films with the deposition times lower than 10 min, and that Cl concentration decreased with increasing the deposition time above 3 min. These results indicate that the films containing the chlorides of Cd, Te and C in addition to CdTe are formed in the initial stage of the CSS deposition using a mixture of CdTe and CdCl2 powder as a source. Cross‐sectional images revealed that the grain size was decreased by the effect of Cl‐doping. Furthermore, current‐voltage (I ‐V) characteristics of the CdTe/graphite structures were measured, and it was found that the resistivity of the Cl‐doped CdTe layer was much higher than that of the undoped CdTe layer. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:17.009612-05:
      DOI: 10.1002/pssc.201400257
       
  • Optimization of preparation technology of ZnO and ZnO: Al thin films for
           solar cell applications
    • Authors: Elnur Bagiyev; Narmina Balayeva, Yegana Aliyeva, Afet Kerimova, Rusif Valiyev, Zamin Mamiyev, Nagi Gasimov, Ayaz Bayramov
      Pages: 536 - 539
      Abstract: ZnO and ZnO: Al thin films of about 100 nm thicknesses were deposited by magnetron sputtering method at 200‐400 °C substrate temperatures under oxygen/argon gas mixture with different O/Ar ratio (0‐6%O2). The higher crystallinities for ZnO: Al and ZnO films are achieved at 400 °C substrate temperature under 0% and 4% (O/Ar) mixture ratios, respectively. The films were characterized by X‐ray diffraction (XRD), spectroscopic ellipsometery (SE), photoluminescence spectroscopy, and atomic force microscopy (AFM) methods. Electrical, optical, and luminescent properties depending on crystallinities of the obtained films were studied. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:22.542009-05:
      DOI: 10.1002/pssc.201400364
       
  • Band gap and optical transmission in the Fibonacci type
           one‐dimensional A5B6C7 based photonic crystals
    • Authors: Sevket Simsek; Husnu Koc, Selami Palaz, Oral Oltulu, Amirullah M. Mamedov, Ekmel Ozbay
      Pages: 540 - 544
      Abstract: In this work, we present an investigation of the optical properties and band structure calculations for the photonic crystal structures (PCs) based on one‐dimensional (1D) photonic crystal. Here we use 1D A5B6C7(A:Sb; B:S,Se; C:I) based layers in air background. We have theoretically calculated photonic band structure and optical properties of A5B6C7(A:Sb; B:S,Se; C:I) based PCs. In our simulation, we employed the finite‐difference time domain (FDTD) technique and the plane wave expansion method (PWE) which implies the solution of Maxwell equations with centered finite‐difference expressions for the space and time derivatives. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:17.21244-05:0
      DOI: 10.1002/pssc.201400244
       
  • Epitaxial growth of chromium nitride thin films with addition of silicon
    • Authors: Kazuma Suzuki; Tsuneo Suzuki, Toshiyuki Endo, Tadachika Nakayama, Hisayuki Suematsu, Koichi Niihara
      Pages: 545 - 548
      Abstract: Epitaxial Cr‐Si‐N thin films were prepared on MgO (100) substrates with a misfit of ‐1.7% with respect to CrN, by pulsed laser deposition. The Si content in the thin films were controlled by varying the ratio of target surface area of Si for Cr. X‐ray diffraction and microstructure observation showed that the thin films were epitaxially grown with the Si contents up to 10 mol% and no grain boundary could be observed. It was considered that the epitaxial thin films consisted of (Cr,Si)N phase, which was synthesized by partial replacement of Cr in CrN lattice with Si. The thin films with the Si contents above 11 mol% formed the polycrystalline. The hardness of the epitaxial Cr‐Si‐N thin films increased with increasing the Si content and the thin films showed the maximum hardness value of 51 GPa. It was considered that the hardening was caused by dissolution of Si in CrN. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:49.071633-05:
      DOI: 10.1002/pssc.201400281
       
  • Crystallization mechanism of sol‐gel synthesized spinel LiMn2O4
    • Authors: K. Kushida; K. Kuriyama
      Pages: 549 - 552
      Abstract: Crystallization mechanism of sol‐gel synthesized spinel LiMn2O4 is studied by a differential scanning calorimetry (DSC) method. Lithium acetate and manganese acetate are dissolved in methanol in the atomic ratio of 1:2 (Li:Mn) with citric acid as a chelating agent, leading to a sol solution. A Li‐Mn gel precursor is obtained by partly evaporating the sol solution. A large exothermic reaction of the Li‐Mn gel starts at 280 °C, indicating that the combustions of C and H atoms released from the gel occur above 280 °C. After the rise in temperature to 290 °C, the exothermic reaction of the gel continues at the constant temperature of 290 °C, indicating that the rearrangement of Li, Mn and O atoms for the crystallization into the spinel structure mainly occurs at 290 °C. This suggests that annealing the Li‐Mn gel precursor above 290 °C is necessary to obtain spinel LiMn2O4. During the exothermic reaction, Mn atoms released from the gel occupy the octahedral sites in the spinel framework of O, and Li atoms also released are inserted into the tetrahedral sites. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:11.073234-05:
      DOI: 10.1002/pssc.201400289
       
  • Semiconducting asphaltene thin films: preparation and characterization
    • Authors: Ibrahim M. Nassar; Zamin Mamiyev, Khuraman Khalilova, Eldar Mammadov, Yegana Aliyeva, Oktay Alekperov, Ayaz Bayramov, Nazim Mamedov
      Pages: 553 - 555
      Abstract: Asphaltene thin films of 100‐500 nm thicknesses were deposited on soda lime glass substrates from toluene solution by spray pyrolysis method. Atomic force microscopy (AFM), photoluminescence (PL), spectroscopic ellipsometry (SE), and electron paramagnetic resonance (EPR) methods were used for characterization of the films. The obtained films were found to be broad band semiconducting material with band gap energy ∼ 3.1 eV and exhibited n‐type conductivity with resistivity ρ ∼ 8·102Ω·cm. Concentration of free radicals and g‐factor were about of ∼ 1018 spin/g and 2.00307, respec­tively. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:20:10.17852-05:0
      DOI: 10.1002/pssc.201400365
       
  • Morphological and structural modifications of chemically‐prepared
           emeraldine polyaniline and zinc oxide in PAni‐ZnO composite
    • Authors: Reynaldo M. Vequizo; Filchito Renee G. Bagsican, Majvell Kay G. Odarve
      Pages: 556 - 559
      Abstract: In this paper, the characteristic changes on the surface morphology and structure of both emeraldine polyaniline (PAni) and ZnO films in the chemically‐prepared PAni‐ZnO composite are presented. The PAni‐ZnO composite on amorphous glass substrate was fabricated utilizing chemical bath deposition technique. The ZnO films were first synthesized using appropriate amounts of zinc sulphate and ammonium hydroxide. Emeraldine form polyaniline films were then grown on as‐prepared ZnO films using appropriate amounts of aniline hydrochloride and ammonium peroxydisulphate. The formation of zinc hydroxychloride hexagonal‐plate structures in the composite film resulted to morphological and structural modifications of PAni and ZnO composite films. The highly‐crystalline emeraldine polyaniline became amorphous when deposited as part of the composite while increased tensile strain was observed for ZnO in the composite due to stretching‐effect caused by zinc hydroxychloride along the outward‐planar direction. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:47.985294-05:
      DOI: 10.1002/pssc.201400311
       
  • Effects of Zn‐dopant on structural properties and electrochromic
           performance of sol‐gel derived NiO thin films
    • Authors: Russameeruk Noonuruk; Wanichaya Mekprasart1, Wisanu Pecharapa
      Pages: 560 - 563
      Abstract: Zn‐doped NiO thin films were prepared by sol‐gel spin‐coating method onto transparent conducting substrates using nickel acetate tetrahydrate and zinc acetate dehydrate as starting precursors. Effects of zinc doping content on the structural, optical and electrochromic properties of NiO films were investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, field emission‐scanning electron microscope, atomic force microscopy, UV‐VIS spectrophotometer and cyclic voltammetry. The results reveal that Zn doping has significant influence on crystallinity deterioration, surface topography alternation and electrochromic performance of the films. The expansion of active surface area due to reduced crystallinity of the films resulting to the increase of charge transfer in the electrochemical reaction. It is indicated that electrochromic performance of sol‐gel derived NiO films can be ameliorated by the incorporation of Zn additive at specific content. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:14.641078-05:
      DOI: 10.1002/pssc.201400303
       
  • Study of the synthesis of self‐ assembled tin disulfide
           nanoparticles prepared by a low‐cost process
    • Authors: Arturo Méndez‐López; Arturo Morales‐Acevedo, Yuliana de Jesús Acosta‐Silva, Hironori Katagiri, Yasuhiro Matsumoto, Orlando Zelaya‐Angel, Mauricio Ortega‐López
      Pages: 564 - 567
      Abstract: Oleylamine‐capped tin disulfide nanoparticles were prepared by the hot‐injection method using tin (II) chloride (SnCl2.5H2O) and thioacetamide as tin (II) and sulfur precursors, respectively. The as‐prepared nanoparticles were rinsed with ethanol or toluene, and their structural and morphological were assessed by X‐ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The obtained nanoparticles were single‐phase SnS2 with hexagonal structure. These nanoparticles self‐assembled to produce spherical 40‐50 nm nanostructures after ethanol evaporation, whilst rhombohedral‐shaped nanostructures or round‐edge nanoribbons were produced after the toluene evaporation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:26.654532-05:
      DOI: 10.1002/pssc.201400271
       
  • Growth and characteristics of amorphous silica‐modified polyaniline
           films for ammonia sensor application
    • Authors: Majvell Kay Odarve; Reynaldo Vequizo
      Pages: 568 - 571
      Abstract: The characteristic properties of the nanostructured polyaniline (PAni) films synthesized via chemical oxidative polymerization of aniline on glass substrates using amorphous cristobalite silica (SiO2) as structural growth director are presented in this study. The change in the resistance of the sample was monitored upon exposure to ammonia gas using two‐probe method for two cycles, 40 min each. The structural and morphological property of the PAni/SiO2 samples were studied and compared to PAni samples alone using FTIR spectroscopy and scanning electron microscopy. It was found out that PAni/SiO2 films have higher and uniform response to ammonia with good repeatability during the two cycles and recovery upon removal of ammonia source. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:13.148346-05:
      DOI: 10.1002/pssc.201400318
       
  • Synthesis and characterization of nanocrystalline hydroxyapatite and
           biphasic calcium phosphate using Ca(OH)2 and (NH4)H2PO4
    • Authors: Romnick Unabia; Joy Cristy Piagola, John Robert Guerrero, Reynaldo Vequizo, Jess Gambe, Majvell Kay Odarve, Bianca Rae Sambo
      Pages: 572 - 575
      Abstract: In this study, nanocrystalline hydroxyapatite and biphasic calcium phosphate prepared via wet chemical precipitation technique in an isolated N2 environment that utilizes calcium hydroxide and ammonium dihydrogenphosphate as main precursors, is presented. Formation of predominantly hydroxyapatite with increasing crystallinity from 39.6 to 88.3% with corresponding crystallite sizes of ∼20.6 and ∼46.6 nm were found for the as‐grown and the annealed powders, respectively. Partly phase transition of hydroxyapatite to β‐TCP phase forming biphasic calcium phosphate was observed in the 900 oC annealed powders. Aggregated structures with nanopores were depicted on the surface of the as‐grown sample while interconnected worm‐like structures with voids forming nanopores were found for the sample annealed at 900 oC. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:46.894894-05:
      DOI: 10.1002/pssc.201400319
       
  • Effect of supercritical carbon dioxide treatment on the polarons of
           HCl‐doped polyaniline films
    • Authors: J. G. Fernando; R. M. Vequizo, M. K. G. Odarve, B. R. B. Sambo, R. M. Malaluan, L. A. M. Malaluan
      Pages: 576 - 579
      Abstract: In situ HCl‐doped polyaniline films were synthesized on glass substrates via chemical oxidative polymerization of aniline using ammonium peroxydisulfate as oxidant. The films were treated with supercritical carbon dioxide (SC‐CO2) at 30 MPa and 40 °C for 30 minutes. The physico‐chemical and electrical properties of the films were determined to establish the effect of supercritical carbon dioxide treatment on the polaron structures of polyaniline films. The treatment removed limited number of polarons which affected the properties of polyaniline. The treated films remained conducting despite that the conductance decreased substantially. The treatment enhanced the quinoid character of the films and altered the HOMO‐LUMO transitions. In addition, SC‐CO2 treatment was unable to remove the PANI precipitations adhering on the surface of the films. A mechanism on the effect of SC‐CO2 interaction to HCl‐doped PANI films was proposed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:06.432144-05:
      DOI: 10.1002/pssc.201400262
       
  • Properties of in situ HCl‐doped emeraldine polyaniline on n
           ‐Si(100) substrates for diode application
    • Authors: J. P. B. Ontolan; P. A. M. Alcantara, R. M. Vequizo, M. K. Odarve, B. R. B. Sambo
      Pages: 580 - 583
      Abstract: In this study, the characteristic physicochemical and electrical properties of HCl‐doped polyaniline (PAni) films grown via oxidative chemical polymerization of aniline on n ‐Si(100) are presented. Two exothermic processes were found for 0.2 M HCl solution during aniline polymerization while all others underwent one exothermic process only. All polyaniline films were of emeraldine salt form that exhibited connected rod‐like to agglomerated grains and dendritic surface morphologies on top of wetting layer with increasing hydrochloric acid concentration. Rectifying behaviour of p‐ PAni/n ‐Si(100) heterojunctions were also found indicating the formation of p‐n junction between p ‐PAni and n ‐Si(100). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:43.715708-05:
      DOI: 10.1002/pssc.201400328
       
  • Deep absorption band in Cu(In,Ga)Se2 thin films and solar cells observed
           by transparent piezoelectric photothermal spectroscopy
    • Authors: Sho Shirakata; Akiko Atarashi, Masakazu Yagi
      Pages: 584 - 587
      Abstract: The photo‐acoustic spectroscopy (PAS) using a transparent piezoelectric photo‐thermal (Tr‐PPT) method was carried out on Cu(In,Ga)Se2 (CIGS) thin films (both CIGS/Mo/SLG and CdS/CIGS/Mo/SLG) and solar cells (ZnO/CdS/CIGS/Mo/SLG). Using the Tr‐PPT method, the high background absorption in the below gap region observed in both a microphone and a conventional transducer PAS spectra was strongly reduced. This high background absorption came from the CIGS/Mo interface. This result proves that the Tr‐PPT PAS is the surface sensitive method. In the below‐band region, a bell‐shape deep absorption band has been observed at 0.76 eV, in which a full‐width at the half‐maximum value was 70‐120 meV. This deep absorption band was observed for both CdS/CIGS/Mo/SLG and ZnO/CdS/CIGS/Mo/SLG structures. The peak energy of the absorption band was independent of the alloy composition for 0.25≤Ga/III≤0.58. Intensity of the PA signal was negatively correlated to the Na concentration at the CIGS film surface. The origin of the 0.76 eV peak is discussed with relation to native defects such as a Cu‐vacancy‐related defect (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:13.253569-05:
      DOI: 10.1002/pssc.201400284
       
  • Structural characterisation of Cu2.04Zn0.91Sn1.05S2.08Se1.92
    • Authors: G. Gurieva; M. Dimitrievska, S. Zander, A. Pérez‐Rodríguez, V. Izquierdo‐Roca, S. Schorr
      Pages: 588 - 591
      Abstract: Quaternary Cu2ZnSn(S1‐xSex)4 compounds are promising semiconductor materials for absorber layer in thin film solar cells. Record efficiency devices (12.6%) exhibit an off‐stoichiometric composition of the absorber layer. These deviations from stoichiometry cause intrinsic point defects, which determine the electronic properties of the semiconductor significantly. A structural analysis of a nearly C‐type off‐stoichiometric Cu and Sn rich and Zn poor Cu2ZnSn(S1‐xSex)4 mixed crystal with x=0.48 by a neutron diffraction investigation was performed. The average neutron scattering length method was applied, showing that the mixed crystal adopts the kesterite type structure. A detailed cation distribution analysis revealed the occurrence of ZnCu(2a) and SnZn anti‐site point defects additional to the Cu‐Zn disorder in the planes at z=1/4 and 3/4. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:23.574279-05:
      DOI: 10.1002/pssc.201400307
       
  • Spectroscopic ellipsometry studies of as‐prepared and annealed CdS:O
           thin films
    • Authors: Khuraman Khalilova; YongGu Shim, Ilham Hasanov, Ryo Asaba, Kazuki Wakita, Nazim Mamedov
      Pages: 592 - 595
      Abstract: Cadmium sulfide thin films on soda lime substrates were obtained by rf‐magnetron sputtering in argon‐oxygen atmosphere. As‐prepared and vacuum annealed films were then studied by spectroscopic ellipsometry at room temperature over photon energy range from 0.5 to 6 eV. The obtained ellipsometric data were treated using optical dispersion models based on Gaussian type oscillators. Dielectric function of oxygen‐free films, as well as those obtained under 3% of O/Ar partial pressure was reliably restored. At the same time, dielectric function obtained for 5% CdS:O can be regarded only as an average over several materials since our XPS examination disclosed presence of several compounds in thin films deposited at O/Ar ratios higher than 3%. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:41.579987-05:
      DOI: 10.1002/pssc.201400272
       
  • High‐performance AlGaN/AlN/GaN high electron mobility transistor
           with broad gate‐to‐source operation voltages
    • Authors: Jung‐Hui Tsai; Chung‐Cheng Chiang, Fu‐Min Wang
      Pages: 596 - 599
      Abstract: In this article, a high‐performance AlGaN/AlN/GaN high electron mobility transistor (HEMT) with broad gate‐to‐source operation voltages is fabricated and demonstrated. The experimental results exhibit a maximum extrinsic transconductance of 94.2 mS/mm at VGS = ‐2.58 V and a threshold voltage of ‐3.68 V at drain output current of 1 mA/mm.The insertion of an AlN interfacial layer can enhance the carrier confinement ability in channel and extend the gate operation voltage to +5 V. Furthermore, the effect of gate recess on device performance is investigated by two‐dimensional simulation. The simulated results show that the AlGaN/AlN/GaN HEMT with gate recess structure has higher equivalent Schottky barrier height, larger electron concentration in channel, larger drain output current and transconductance as compared with the device without gate recess structure. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:16.398381-05:
      DOI: 10.1002/pssc.201400241
       
  • Depolarization effect in rare‐earth doped Y2O3 films in blue and UV
           spectral range
    • Authors: Naghi Gasimov; Eldar Mammadov, Anne L. Joudrier, Sardar Babayev, Irada Mamedova, Christian Andriamiadamanana, Nazim Mamedov, Negar Naghavi, Jean F. Guillemoles
      Pages: 600 - 604
      Abstract: The 200 to 300 nm thick, Er and Er,Yb doped Y2O3 films deposited onto silicon substrate by spin coating have been studied by spectroscopic ellipsometry over the 192‐1680 nm spectral range at room temperature. All samples have been found to be strongly depolarizing in the blue and UV part of the spectrum. Complimentary examination of the sample surfaces, using confocal photoluminescence microscopy has disclosed the non‐uniform distribution of the rare‐earth dopants. The depolarization effects have then been modeled and found to be best reproduced by taking the thickness non‐uniformity as the main source of depolarization. The optical constants of the studied films have been determined after four‐step modeling with sequential decrease of the mean square error. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T12:10:34.102847-05:
      DOI: 10.1002/pssc.201400301
       
  • Temperature dependent spectroscopic ellipsometry of Ag2Se and Ag2S with
           phase transitions from ionic to superionic conductivity state
    • Authors: O. Alekperov; N. Gasimov, Kh. Khalilova, Y. Shim, R. Paucar, N. Abdulzade, O. Samedov, Z. Jahangirli, E. Nakhmedov, K. Wakita, N. Mamedov
      Pages: 605 - 609
      Abstract: Temperature dependent infrared (IR) and optical spectroscopic ellipsometry methods are used to investigate peculiarities of the transitions from the ionic conductivity to the superionic conductivity states in Ag2S and Ag2Se compounds. The structural phase transitions (SPTs), known as β→α transition in these semiconductors, are investigated also with spectroscopic ellipsometry methods. The electronic band structure of Ag2S at the SPT changes sharply from the monoclinic to the bcc phase, which occurs at T = 453 K in the super ionic conductivity state, where all the interband transitions in optic region, corresponding to the monoclinic structure of β‐phase, disappear. The α‐phase of Ag2S is characterised with new lines in the dielectric functions ε1 and ε2, which arise at 5‐6.5 eV. The interband transitions do not change in the SPT from the orthorhombic to the bcc in Ag2Se, which occurs at T > 406 K. In IR ellipsometry for the degenerated Ag2Se, the free carriers' plasma energy is displaced abruptly from ħω=0.075 eV at T=300 K to ħω=0.125 eV at T=338 K. The same effect is seen in the IR ellipsometry for Ag2S, where negative ε1 appears at T=434‐440 K. These facts indicate a drastic increase of the free carriers concentrations in both of the semiconductors at temperatures before the β→α SPT. In Ag2S the second abrupt shift of the free carriers plasma energy from 0.035eV to 0.1 eV occurs at T=453 K, corresponding to β→ α SPT. The second shift is due to the electronic band structure change of Ag2S. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:37.67887-05:0
      DOI: 10.1002/pssc.201400367
       
  • Impedance spectroscopy study of phase transitions to ionic and superionic
           conductivity states in Ag2S and Ag2Se
    • Authors: O. Alekperov; O. Samedov, R. Paucar, N. Abdulzade, E. Nakhmedov, A. Nadjafov, K. Wakita, N. Mamedov
      Pages: 610 - 614
      Abstract: The percolation threshold (PT) temperatures Tc1,c2 of two non‐equivalent Ag+1,2 ions in Ag2S and Ag2Se lattices were determined from the temperature dependence of low‐frequency (25‐106Hz) impedance spectroscopy measurements. At PT temperatures Tc1≈200 K and Tc2≈ 334 K, an abrupt increase of the dielectric function ε1(ω) of Ag2Se crystal from a very large negative value, ε1 ≈‐109, to a very large positive value ε1≈ 106 was observed, which is assumed to result from the dipole relaxation. The strong peaks of the dielectric losses ε2(ω), tgδ(ω) and impedance Z in Ag2Se were also determined at Tc1,c2. Two significant peaks in ε1(ω), ε2(ω)and tgδ(ω) were observed at Tc1≈ 312‐320 K. and Tc2≈ 380‐430 K in the temperature dependences of these parameters. The measured parameters decreased significantly with increasing frequency, confirming the long relaxation times. The drastic decrease at T > 430 K of ε1from a very large positive value 109to a very large negative one ‐108 is in accordance with infrared (IR) ellipsometry measurements; this indicates that electrons of Ag+‐ ions are ionized because of the high dielectric function screening of lattice sites before the known β→α structural phase transition from monoclinic to a body‐centered cubic (bcc) structure. In addition, the activation energies of Ag+1,2 ions were estimated for Ag2S and Ag2Se crystals. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-24T03:30:08.269573-05:
      DOI: 10.1002/pssc.201400366
       
  • EPR and SPM studies of Zn‐Ni ferrites
    • Authors: Sh. N. Aliyeva; Y. N. Aliyeva, A. I. Nadjafov, I. S. Hasanov, E. K. Huseynov, T. R. Mehdiyev
      Pages: 615 - 619
      Abstract: Electron paramagnetic resonance studies have been carried out over 3.7‐300 K on micropowders of Ni1‐xZnxFe2O4 ferrites, obtained by high temperature synthesis and preliminary characterized by X‐ray diffraction and differential scanning calorimetry in a wide range of tempera‐tures. Complimentary, scanning probe microscopy, compris‐ing atomic and magnetic force microscopies has been applied to polycrystalline Ni1‐xZnxFe2O4thin films. The correlation between X‐ray and differential scanning calorimetry data has been observed. Deconvolution of the obtained paramagnetic resonance spectra into Gaussian components and their further analysis have allowed retrival of the compensation points of the magnetc momenta of the sublattices of Ni1‐xZnxFe2O4, as well as of superparamagnetism effect and g‐factors dispersion verified by studies on polycrystalline thin films. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:08.151943-05:
      DOI: 10.1002/pssc.201400273
       
  • Electronic structure of YbNiX3 (X =Si, Ge) studied by hard X‐ray
           photoemission spectroscopy
    • Authors: Hitoshi Sato; Yuki Utsumi, Junichi Kodama, Heisuke Nagata, Marcos A. Avila, Raquel A. Ribeiro, Kazunori Umeo, Toshiro Takabatake, Kojiro Mimura, Satoru Motonami, Hiroaki Anzai, Shigenori Ueda, Kenya Shimada, Hirofumi Namatame, Masaki Taniguchi
      Pages: 620 - 623
      Abstract: lectronic structure of the Kondo lattices YbNiX3 (X =Si, Ge) has been investigated by means of hard x‐ray photoemission spectroscopy (HAXPES) with hν = 5.95 keV. From the Yb 3d HAXPES spectra, the Yb valence in YbNiSi3 is estimated to be ∼ 2.92, which is almost temperature‐independent. On the other hand, the valence in YbNiGe3 is estimated to be 2.48 at 300 K, showing significant valence fluctuation, and gradually decreases to 2.41 at 20 K on cooling. The Ni 2p3/2 and Yb3+ 4f peaks exhibit opposite energy shifts amounting to ∼ 0.6 eV between YbNiSi3 and YbNiGe3. We propose a simple model for the electronic structure of YbNiX3 based on the HAXPES results. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:12.315085-05:
      DOI: 10.1002/pssc.201400312
       
  • Characterization and effect of calcination temperature on structural
           properties of spinel zinc aluminate synthesized via Co‐precipitation
           process
    • Authors: Wanichaya Mekprasart; Suchada Worasawat, Thanit Tangcharoen, Wisanu Pecharapa
      Pages: 624 - 627
      Abstract: Zinc aluminate (ZnAl2O4) nanopowders were synthesized by co‐precipitation method using zinc chloride and aluminum chloride as starting precursors. The calcination temperature which was a crucial preparation factor was varied and its influence on relevant physical properties of the product was investigated. Structural properties of synthesized nanoparticles were investigated by X‐ray diffraction, X‐ray absorption spectroscopy, scanning electron microscope, and Raman spectroscopy. The results suggest that that ZnAl2O4 in spinel structure with high crystallinity can be obtained after calcination beyond specific temperature affirmed by XRD results. Raman result indicates the correlated chemical bonding relating to the formation of ZnAl2O4 structure. Meanwhile, the Zn K‐edge X‐ray absorption near‐edge structure (XANES) spectra of these samples with different calcination temperature obtained from the synchrotron X‐ray absorption spectroscopy measurement show the existence of accurate oxidation state for zinc ion (Zn2+) in the spinel crystal structure. Moreover, it is revealed that the calcination temperature has significant effect on the local environment of the zinc absorbing atoms through the interesting change of white line appearance. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T12:10:36.314966-05:
      DOI: 10.1002/pssc.201400292
       
  • IR ellipsometry of silk fibroin films on Al nanoislands
    • Authors: Oktay K. Gasymov; Arzu Aydemirova, Oktay Alekperov, Rasim B. Aslanov, Khuraman Khalilova, Nagi Gasimov, Nazim Mamedov, Irada Mamedova, Sardar Babayev, Namig Gasanov
      Pages: 628 - 630
      Abstract: Infrared spectroscopic ellipsometry (IRSE) is a powerful tool for the characterization of various types of organic and inorganic films. In application to protein films, IRSE can be utilized to detect structural changes, orientation of specific group, etc. Because of sensitivity, enhanced IRSE will be very useful to study protein thin films. Here we show that fibroin films on Al mirror display surface‐enhanced infrared spectroscopic ellipsometry (SEIRSE). AFM data indicate that nanoislands on the Al mirror are responsible for the plasmon‐enhanced mechanism. SEIRSE for fibroin films shows non‐uniform enhancement across the spectrum. Possible mechanisms of such enhancement are provided. Evidently, as proposed previously, at least two mechanisms, the electromagnetic (EM) and chemical, are expected to contribute to the enhancement. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:34.065021-05:
      DOI: 10.1002/pssc.201500005
       
  • Numerical analysis of Cu(In,Ga)Se2 solar cells with high defect density
           layer at back side of absorber
    • Authors: Naoki Ashida; Masashi Murata, Daisuke Hironiwa, Jakapan Chantana, Hikaru Uegaki, Takashi Minemoto
      Pages: 638 - 642
      Abstract: The 2‐µm‐thick Cu(In,Ga)Se2 (CIGS) absorber is divided into two areas, low defect density layer (front side) and high defect density layer (back side). In this paper, the optimized thickness of the low defect density layer and the high defect density layer is estimated for high cell performance. The optimization is performed by using device simulator. As a result, the high defect density layer (back side) has no influence on cell performance in the case of CIGS with high optical‐absorption coefficient owing to almost no photocarriers, which are generated in the high defect density layer. In addition, the necessary thickness for absorbing all light to obtain high conversion efficiency is considered. CIGS with graded band profile can be thinner than that with flat band profile for high cell performance owing to the aid of back surface field. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:50.039268-05:
      DOI: 10.1002/pssc.201400242
       
  • Advancement in treating some features of CIGS thin film solar cells during
           manufacturing
    • Authors: Poonam Sharma; Zhongli Li, Hsueh Hsin Chang, Arya Jagadhamma Letha, Lexi Shao, Yafei Zhang, Huey Liang Hwang
      Pages: 643 - 646
      Abstract: In‐line sputtering and selenization have become the industrial standard, but it is difficult to predict and control the local chemical composition of the film. The present communication reports on the material design, device design and process design. These designs use parameters that are closely related to their chemical compositions, as a variation in composition leads to modification of the Poisson equation, current equation and continuity equation. Therefore, there is a need to build a model that relates the optoelectrical properties and device structural parameters that will be loaded into the process simulation, to obtain the complete set of process control parameters. The detailed optical and electrical properties are also investigated for the development of an analytical solar cell simulator. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-24T03:30:06.90874-05:0
      DOI: 10.1002/pssc.201400315
       
  • Mechanical, electronic, and optical properties of the A4B6 layered
           ferroelectrics: ab initio calculation
    • Authors: Husnu Koc; Sevket Simsek, Selami Palaz, Oral Oltulu, Amirullah M. Mamedov, Ekmel Ozbay
      Pages: 651 - 658
      Abstract: We have performed a first principles study of the structural, elastic and electronic properties of orthorhombic SnS and GeS compounds using the density functional theory within the local density approximation. The second‐order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, Debye temperature, and hardness have also been estimated in the present work. All of the calculated modulus and Poisson's ratio for SnS were less than the same parameters for GeS. Our calculations have discovered the large anisotropy of elastic parameters in the (100) and (010)‐planes for both compounds. The band structures of orthorhombic SnS and GeS have been calculated along high symmetry directions in the first Brillouin zone (BZ). The calculation results for the band gap of Sn(Ge)S gave Eg = 0.256 eV (0.852 eV) and has an indirect character for an interband transition. The real and imaginary parts of dielectric functions and (by using these results) the optical constant such as energy‐loss function, the effective number of valance electrons and the effective optical dielectric constant were calculated. All of the principal features and singularities of the dielectric functions for both compounds were found in the energy region between 2 eV and 20 eV. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:36.016366-05:
      DOI: 10.1002/pssc.201400245
       
  • Interaction of methyl radical (CH3) with C60 fullerene: Density functional
           theory (DFT) study
    • Authors: Hiroto Tachikawa; Tetsuji Iyama
      Pages: 659 - 663
      Abstract: The addition reaction of methyl radical (CH3) to fullerene (C60) surface has been investigated by means of density functional theory (DFT) method. The DFT calculation showed that the CH3 radical binds directly to the carbon atom of C60 and a strong C‐C single bond is formed. The binding energy of CH3 to C60was calculated to be 35.1 kcal/mol at the CAM‐B3LYP/6‐311G(d,p) level. The potential energy curve plotted as a function of a distance of CH3 from the C60 surface showed that the CH3 radical can approach to the carbon atom with very low activation barrier: the barrier height was calculated to be 2.8 kcal/mol. The electronic states of CH3‐C60 complex were discussed on the basis of theoretical results. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:38.696866-05:
      DOI: 10.1002/pssc.201400354
       
  • Ab initio calculations of phonon dispersion and lattice dynamics in
           TlGaTe2
    • Authors: Vusala Jafarova; Guseyn Orudzhev, Raul Paucar, Oktay Alekperov, YongGu Shim, Kazuki Wakita, Nazim Mamedov, Nadir Abdullayev, Arzu Najafov
      Pages: 664 - 667
      Abstract: This work reports the results of DFT‐based calculations of phonon spectra of TlGaTe2. The dispersion of phonon bands was calculated along the directions of Brillouin zone (BZ) that include symmetry points. The calculated phonon frequencies at the centre of BZ were compared with those obtained by Raman spectroscopy with the aid of a confocal laser microscopy system. A fairly good agreement between the calculated and experimental data was found. Complimentary, molar heat capacity at constant volume and Debye temperature were calculated in the range 5÷500 K on the base of the obtained phonon density of states. The obtained temperature dependencies were compared with available experimental data.The results of comparison were satisfactory. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:39.969455-05:
      DOI: 10.1002/pssc.201400351
       
  • Band structure and vacancy formation in β‐Ag2S: Ab‐initio
           study
    • Authors: Oktay Alekberov; Zakir Jahangirli, Raul Paucar, Suma Huseynova, Nigar Abdulzade, Anver Nakhmedov, Kazuki Wakita, Nazim Mamedov
      Pages: 672 - 675
      Abstract: Electronic band structure, together with formation energy of native point defects has been studied for β‐Ag2S superionic material. The density‐functional full‐potential calculations have been carried out for perfect crystal and defect structure. In latter case a 96‐atom supercell has been composed and account of structural relaxation around a vacancy has been taken up to second nearest neighbor. Formation energies of point defects have been obtained and compared. According to comparison, cation vacancies are the dominant intrinsic defects in β‐Ag2S and transition into a state with high ionic conductivity is probably related with their abrupt concentration increase with increasing temperature. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:42.671878-05:
      DOI: 10.1002/pssc.201400335
       
  • Optimization of CIGSe bottom cell for spectral splitting device
           application
    • Authors: Z. Jehl‐Li‐Kao; Hirofumi Fukai, Isamu Matsuyama, T. Nakada
      Pages: 676 - 679
      Abstract: We investigate on narrow bandgap CIGSe solar cells for tandem application in a spectral splitting devices. Numerical simulations using SCAPS are performed to optimize the Ga content throughout the absorber layer, depending on the illumination condition (AM 1.5 and tandem conditions using two different splitting filters; 620 nm and 880 nm). The simulations show a strong dependence of the efficiency on the minimum bandgap of the absorber, but not on the depth of the narrow bandgap region. Narrow bandgap CIGSe solar cells are experimentally realized and electrically characterized. A similar trend as what was deduced from the simulation is observed on the experiments when the solar cells are characterized in the tandem conditions. For the 880 nm splitting filter, an efficiency of 5.5% is experimentally obtained with a minimum bandgap of 1.05 eV. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:35.001401-05:
      DOI: 10.1002/pssc.201400308
       
  • Synthesis of Cu(In,Ga)Se2 crystals using a crank ball mill
    • Authors: Suzuka Yamada; Hideki Noji, Tomoichiro Okamoto, Yoji Akaki
      Pages: 684 - 687
      Abstract: Cu(In,Ga)Se2 (CIGS) crystals were synthesized by a mechanochemical (MC) process using a crank ball mill. The molar ratios of starting materials were Cu:In:Ga:Se=1:1‐x:x:2 (0≤x≤1) and Cu:In:Ga:Se=1:0.7:0.3:y (2≤y≤3). The reaction time reduced with decreasing Se and Ga molar ratios. The collection rate decreased with longer reaction times. From XRD patterns, we confirmed that the CuInSe2 and/or CuGaSe2crystals were successfully grown when the powders reacted. Although the crystals grown with a selenium molar ration of 2 were Se‐poor, those grown at a molar ratio of 3 were Se‐rich. When Se increasing molar ratio, Cu, In, and Ga were away from the stoichiometric. With a molar ratio of Cu:In:Ga:Se=1:0.7:0.3:2.5∼2.7, their composition became stoichiometric. Crystal morphology was varied. CIGS crystals were thus successfully synthesized using a crank ball mill. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-05-05T07:40:42.472061-05:
      DOI: 10.1002/pssc.201400327
       
  • RF magnetron sputtering deposition of amorphous Zn–Sn–O thin
           films as a buffer layer for CIS solar cells
    • Authors: Shao‐Wei Chang; Kaoru Ishikawa, Mutsumi Sugiyama
      Pages: 688 - 691
      Abstract: Amorphous Zn–Sn–O (α‐ZTO) layers were deposited by RF magnetron sputtering to provide an alternative n‐type buffer layer for CuInSe2 solar cells. Electrical properties, such as the carrier density, mobility, and resistivity were adjusted by controlling the Sn/(Sn+Zn) ratio of the α‐ZTO layer and by regulating the oxygen partial pressure during sputtering. Valence band discontinuities of α‐ZTO/CuInSe2 were determined using photoelectron yield spectroscopy. The band discontinuity at the interface has “spikes” in the conduction band offset. Further, the short circuit current of a CIGS solar cell that uses an α‐ZTO layer was marginally higher compared to one that used a CdS layer. These results represent a step toward developing a safer, cheaper solar cell with higher performance by using an α‐ZTO film instead of a traditional CdS film. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:30.536287-05:
      DOI: 10.1002/pssc.201400255
       
  • Excitonic emission on CuInS2 epitaxial films by pulse laser deposition
    • Authors: Ryo Yoshida; Tseng Po‐Han, Yong‐Gu Shim, Kazuki Wakita
      Pages: 692 - 695
      Abstract: Thin films of epitaxial CuInS2 were deposited on a GaAs substrate at a temperature of 500 ºC by the pulse‐laser‐deposition method. Surface and cross‐section scanning electron microscopy (SEM) images were taken for all the films, with thicknesses estimated to range between 0.5‐1 μm. X‐ray diffraction (XRD) and Raman scattering confirmed the chalcopyrite structure of the films. For a film deposited by a pulse of energy density 0.8 J/cm2, free exciton and bound exciton emissions at 77 K were observed using photoluminescence (PL). The exciton emissions appear only at specific points in a PL‐intensity mapping. In addition, for the points with excitonic emission the composition ratio of the Cu and In was found to be very close to unity compared to other areas without emissions. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:23.95739-05:0
      DOI: 10.1002/pssc.201400352
       
  • Characterization of CuInS2‐Cu2ZnSnS4 crystals grown from the melt
    • Authors: Koichiro Oishi; Kenta Nakamura, Makoto Yamazaki, Shota Fukai, Takuya Shigeno, Hironori Katagiri
      Pages: 696 - 699
      Abstract: Cu2(2.00‐x)((2In)y (ZnSn)(1.00‐y))x S4 crystals were grown from the melt. 23 samples with different x and y values were synthesized by heating constituent elementary Cu, In, S and Zn‐Sn alloy at 1,250 °C for 10 hours in each evacuated fused‐quartz ampule. All samples were characterized by powder X‐ray diffraction analysis. Two peaks are seen at the 112 diffraction positions in 0.3 ≤ y ≤ 0.9. The FWHM of the 112 diffraction peak broadened in 0.2 ≤ y ≤ 0.7. Lattice constants were obtained by Rietveld method using two tetragonal structure models simultaneously in the refinement. Both a and c obtained as CuInS2 phase changed almost linearly in y ≥ 0.7; therefore the existence of CuInS2 phase solid solution containing Zn and Sn was indicated in this region. The miscibility gap was also suggested as the region of 0.2 ≤ y ≤ 0.7 in our results because of the shape and the broadening of the 112 diffraction peaks. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T12:10:32.030877-05:
      DOI: 10.1002/pssc.201400306
       
  • Crystallographic and optical properties of (Cu, Ag)2ZnSnS4 and (Cu,
           Ag)2ZnSnSe4 solid solutions
    • Authors: Weiyan Gong; Takahiro Tabata, Koji Takei, Masaru Morihama, Tsuyoshi Maeda, Takahiro Wada
      Pages: 700 - 703
      Abstract: (Cu1‐xAgx)2ZnSnS4 (CAZTS) and (Cu1‐xAgx)2ZnSnSe4 (CAZTSe) solid solutions with 0 ≤ x ≤ 1.0 were synthesized. Their crystal structures were analyzed by Rietveld refinement of X‐ray diffraction data. The refined lattice constants a of the kesterite‐type CAZTS and CAZTSe increase with Ag content (x) increasing, while their lattice constants c slightly decrease. Therefore, by increasing x, the c /a ratio decreases from 2 for Cu‐based compounds to a value lower than 1.9 for Ag‐based compounds. The band‐gap energies (Eg) of CAZTS and CAZTSe solid solutions were determined by their diffuse reflectance spectra. The reflectance edges of the CAZTS and CAZTSe shifted to the longer wavelength side with Ag content increasing at 0.0 ≤ x ≤ 0.2, while they shifted to the shorter wavelength side at 0.2 ≤ x ≤ 1.0. By increasing x, the Eg of CAZTS decreases from 1.49 eV (x=0.0) to 1.47 (x=0.2) and then increases to 2.01 eV (x=1.0); and the Eg of CAZTSe decreases from 0.98 eV (x=0.0) to 0.95 (x=0.2) and then increases to 1.34 eV (x=1.0). There is small bowing in the band gaps of the CAZTS and CAZTSe systems. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:41.450258-05:
      DOI: 10.1002/pssc.201400343
       
  • Improvement of Cu2ZnSn(S,Se)4 solar cell efficiency by surface treatment
    • Authors: Kento Furuta; Noriyuki Sakai, Takuya Kato, Hiroki Sugimoto, Yasuyoshi Kurokawa, Akira Yamada
      Pages: 704 - 707
      Abstract: Surface treatments for the purpose of contamination elimination and surface passivation were performed to as‐deposited CZTSSe thin films before CdS buffer layer deposition. It was found that HCl etching treatment removes contaminations such as sulfide and oxide on CZTSSe surface and helps enhancement of thiourea treatment carried out after HCl etching. Thiourea treatment drastically improves solar cell characteristics, especially FF and JSC, and it would have the effect of surface passivation, although surface sulfuration does not occur. The improvement of characteristics seems to be due to improvement of the film quality and increase in the width of a depletion layer. As a result, conversion efficiency of CZTSSe solar cells was improved from 6.3% to 10.3% with sequential treatment of HCl etching and thiourea treatment. 10.5% was achieved by air anneal after fabrication with both treatments.
      PubDate: 2015-04-21T05:10:19.329902-05:
      DOI: 10.1002/pssc.201400309
       
  • A 5.1% efficient kesterite Cu2ZnSnS4 (CZTS) thin film solar cell prepared
           using modified sulfurization process
    • Authors: Myeng G. Gang; Kishor V. Gurav, Seung W. Shin, Chang W. Hong, Jung H. Min, Mahesh P. Suryawanshi, Sharad A. Vanalakar, Dong S. Lee, Jin H. Kim
      Pages: 713 - 716
      Abstract: Cu2ZnSnS4 (CZTS) absorber thin films are prepared by sulfurization of sputtered Cu/Sn/Zn (CZT) stacked metallic precursor. The modified sulfurization process is adapted to prepare photovoltaic quality CZTS films. Specifically, sputtered CZT precursor films are sulfurized in sulfur powder contained graphite box using rapid thermal processing furnace at 580 °C for 10 min, in N2(95%) + H2S (5%) atmosphere. The Cu‐poor CZTS films with various Cu/(Zn+Sn) ratio are prepared by varying Cu layer deposition time. The effect of Cu/(Zn+Sn) ratio on the properties of CZTS films is investigated. The CZTS thin film solar cells with Cu/(Zn+Sn)=0.76 shows best conversion efficiency of 5.1% (Voc: 573 mV, Jsc: 18.38 mA/cm2, FF: 0.48%, and active area: 0.31 cm2). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:14.501619-05:
      DOI: 10.1002/pssc.201400285
       
  • Optical properties and electronic energy‐band structure of Cu2ZnSnS4
    • Authors: Shunji Ozaki; Keiji Hoshina, Yuji Usami
      Pages: 717 - 720
      Abstract: Optical properties of the quaternary Cu2ZnSnS4 semiconductor have been studied by optical absorption, photoluminescence, photoreflectance, and thermoreflectance measurements. Optical absorption measurements suggest that Cu2ZnSnS4 is a direct‐gap semiconductor having the band gap of ∼1.46 eV at 11 K. The photoreflectance and thermoreflectance spectra reveal distinct structures at energies of the critical points in the Brillouin zone. By performing the band‐structure calculation, these critical points are successfully assigned to specific points in the Brillouin zone. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:17.349331-05:
      DOI: 10.1002/pssc.201400254
       
  • Impact of water‐rinse treatment on Cu2ZnSnS4 studied by X‐ray
           absorption near‐edge structure analysis
    • Authors: Toshihiko Toyama; Takafumi Konishi, Ryotaro Tsuji, Ryuichiro Maenishi, Akiko Arata, Shinji Yudate, Sho Shirakata
      Pages: 721 - 724
      Abstract: Cu2ZnSnS4 (CZTS) thin‐film solar cells are considered promising for terawatt‐scale production. It has been established that in the fabrication process of CZTS thin‐film solar cells, a water‐rinse treatment for the CZTS surface yields a great improvement in conversion efficiency. We studied the mechanism of the water‐rinse treatment on an aged crystalline‐CZTS sample, using the X‐ray absorption near‐edge structure (XANES) technique, which is highly sensitive for oxidation states of sulfur. The sulfur K‐edge XANES spectra revealed a dramatic change at around 2480 eV after a 3‐min water‐rinse treatment. By comparison with the spectra of reference samples, we posit the removal of surface sulfate cations as a possible source for this behavior. From further comparison with the spectrum of a thin‐film sample, we discuss the use of this short 3‐min treatment time in actual device‐fabrication procedures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:18.726221-05:
      DOI: 10.1002/pssc.201400265
       
  • Fabrication of Cu2ZnSnSe4 thin films by selenization of precursor using
           Cu2ZnSnSe4 compound for photovoltaic applications
    • Authors: M. Nakashima; T. Yamaguchi, K. Kusumoto, S. Yukawa, J. Sasano, M. Izaki
      Pages: 729 - 732
      Abstract: Cu2ZnSnSe4 ingot was synthesized and then used it and Na2Se powder as evaporation materials to prepare a precursor for selenization process in order to fabricate Cu2ZnSnSe4 thin films for solar cell applications. From EPMA analysis, the Sn content in the thin films was approximately constant with increasing Sn mole ratio and the Se content was under 50 at.% in the first experiment. The Se content in the thin films increased to around 50 at.% by the addition of Se layer in second experiment. XRD study showed that the thin films had a kesterite phase in Cu2ZnSnSe4. The Se layer addition enhanced to grow thin films having a close‐packed structure and columnar grains. Cu2ZnSnSe4 thin film solar cells demonstrated Voc= 282 mV, Isc= 3.00 mA/cm2. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:10.003037-05:
      DOI: 10.1002/pssc.201400279
       
  • Cu2ZnSnS4 thin film deposited by pulse laser deposition
    • Authors: Yusuke Watanabe; Hiroki Miura, Yong‐Gu Shim, Kazuki Wakita
      Pages: 733 - 736
      Abstract: In this work, bulk Cu2ZnSnS4 (CZTS) poly‐crystals which were used as a target of the pulse laser deposition (PLD) method were grown using the solid‐phase method. The CZTS poly‐crystals were then investigated using X‐ray diffraction (XRD), Raman spectroscopy, and compositional analyses. It was observed that impure crystal phases were reduced with increasing heat growth duration, and they almost completely disappeared in the crystals grown for 96 h at 980 °C. The lattice constants of the a and c axes were estimated from the XRD data and found to be 5.4307 Å and 10.8680 Å, respectively, which are in good agreement with the standard values of 5.4340 Å and 10.8560 Å, as according to JCPDS Card 01‐075‐4122. Our results indicate that the CZTS poly‐crystals have either a kesterite or a stannite structure. Raman spectra confirmed the existence of CZTS without any secondary phases in the form of binary or ternary sulfides. CZTS poly‐crystals were found to be nearly stoichiometric, and they possessed a uniform composition. CZTS thin films were deposited using the PLD method, and were evaluated using X‐ray diffraction (XRD), composition analysis, and field emission scanning electron microscopy (FE‐SEM). Very few additional impurity phases were detected in CZTS thin films deposited at a pulse energy density of 5 mJ/mm2. Finally, the composition of the CZTS thin films was not consistent with that of the CZTS poly‐crystals as a target of PLD method. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:20:05.325903-05:
      DOI: 10.1002/pssc.201400349
       
  • The effect of dextrin addition during Cu2ZnSnS4 thin film preparation by
           photochemical deposition
    • Authors: Katsuhiko Moriya; Hikaru Shimotsuma, Kunihiko Tanaka, Hisao Uchiki
      Pages: 737 - 740
      Abstract: Cu2ZnSnS4 (CZTS) thin films were prepared by annealing films of Cu2S, ZnS, and SnS2 precursors deposited on a soda‐lime glass substrate by photochemical deposition (PCD) from an aqueous solution containing CuSO4, ZnSO4, SnSO4, and Na2S2O3. This paper discusses the effect of adding dextrin as a titrant during the PCD preparation of CZTS thin films. We investigated the effects of dextrin addition on the surface morphology of the resulting films. The surfaces of films prepared with added dextrin were composed of uniformly sized grains. The results also demonstrate that the surface morphology of photochemically deposited CZTS films can be smooth if the proper additives are employed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:12.205831-05:
      DOI: 10.1002/pssc.201400280
       
  • Surface etching of CZTS absorber layer by Br‐related solution
    • Authors: H. Miyazaki; M. Aono, H. Kishimura, H. Katagiri
      Pages: 741 - 744
      Abstract: Cu2ZnSnS4 (CZTS) material has many advantages for high‐efficiency thin‐film solar cell absorber layer. A detailed study of the surface of the CZTS and the hetero‐interface of the CZTS/buffer layer is important to improve the conversion efficiency of CZTS thin film solar cells. We investigated the surface condition of the CZTS films by carrying out the surface treatment using bromine solution. The activation energy of the etching using bromine solution was estimated from the slope of the line fitting the graph of the temperature dependence of the etching rate. The activation energy is about 0.35 eV. This value suggests that etching mechanism of CZTS using bromine solution is diffusion‐limited process. There were no significant changes in the structural characteristics after surface treatment by X‐ray diffraction and Raman spectroscopy. From the results of X‐ray photoelectron spectroscopy measurements, a relative surface composition was shifted to Cu‐ and Zn‐rich phase after surface treatment. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:24.804012-05:
      DOI: 10.1002/pssc.201400274
       
  • Effect of surface treatment of CZTS absorber layer by ammonia solution
    • Authors: H. Miyazaki; M. Aono, H. Kishimura, H. Katagiri
      Pages: 745 - 748
      Abstract: In this work, we investigated the effect of surface treatment of the Cu2ZnSnS4 (CZTS) thin films using ammonia solution. CZTS thin films were prepared by RF sputtering using single CZTS target with sulfurization process. In order to study the effect of surface treatment using ammonia solution, solution temperature was varied. Structural properties of the samples are almost same with and without ammonia surface treatment measured by XRD and Raman spectroscopy. From the measurement of the chemical composition, the Zn is dissolved by ammonia solution. In addition, the removal rate of oxygen and sodium is different between deionised water and ammonia solution. Ammonia could have prevented their removal from the surface to solution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:22.704809-05:
      DOI: 10.1002/pssc.201400275
       
  • Effects of preferential etching treatment of CZTS absorber layer by
           deionized water
    • Authors: H. Miyazaki; M. Aono, H. Kishimura, H. Katagiri
      Pages: 749 - 752
      Abstract: Cu2ZnSnS4 (CZTS) is one of the promising materials for high efficiency thin film solar cells. Here we report on the chemical and structural characterization of the CZTS thin films before and after the surface treatment using deionized water. X‐ray diffraction and Raman scattering spectroscopy results showed that the deionized water treatment did not affect the bulk characterization. Copper chemical composition ratio increases and sulphur composition ratio decreases with increasing deionized water treatment temperature on the film surface. In the case of the sample treated at 353 K, the surface composition changes to Cu‐rich composition. However, the chemical composition ratio of the bulk still remained before deionized water (DIW) surface treatment. The change in the CZTS surface composition according to the DIW surface treatment temperature, we think these results may help to be studied in CZTS surface in more detail. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-07T11:51:11.043396-05:
      DOI: 10.1002/pssc.201400276
       
  • Investigation of the sulfurization process of Cu2SnS3 thin films and
           estimation of band offsets of Cu2SnS3‐related solar cell structure
    • Authors: Soichi Sato; Hiroki Sumi, Guannan Shi, Mutsumi Sugiyama
      Pages: 757 - 760
      Abstract: The morphological and structural transition of Cu2SnS3 (CTS) thin films during sulfurization was investigated. The surface morphology and re‐evaporation of CTS films strongly depend on the sulfurization temperature. Low temperature sulfurization enables the films to be sulfurized and form CTS without re‐evaporation. Subsequently, the high‐temperature annealing improves the grain size of the CTS film. In addition, the energy band diagrams of the CTS‐related solar cell structures that use various n‐ type oxide semiconductors, such as CdS, ZnO:In2O3(IZO), ZnO, SnO2, and ZnO:SnO2(ZTO) were examined by photoelectron yield spectroscopy. The band diagrams of IZO/CTS, ZnO/CTS, SnO2/CTS, and ZTO/CTS have a TYPE‐I heterostructure known as a “spike” conduction band offset structure, essential for high‐efficiency solar cells. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-21T05:10:21.237337-05:
      DOI: 10.1002/pssc.201400294
       
  • Cu2SnS3 thin film solar cells prepared by thermal crystallization of
           evaporated Cu/Sn precursors in sulfur and tin atmosphere
    • Authors: M. Nakashima; T. Yamaguchi, H. Itani, J. Sasano, M. Izaki
      Pages: 761 - 764
      Abstract: Cu2SnS3 thin films were prepared by crystallization in sulfur and tin mixing atmosphere from the stacked Cu/Sn precursors deposited by sequential evaporation of Sn and Cu elements. From EPMA analysis, the composition of the thin film was approximately constant regardless changing Sn mole ratio in the precursor. However, the composition of inside of the thin films and Mo layer had gradation. The Raman analysis showed that the spectrum corresponded to monoclinic Cu2SnS3. Cu2SnS3 thin films were applied to the fabrication of Cu2SnS3 solar cells. The values of Voc and Isc increased with decreasing Sn mole ratio in the precursor. The largest Voc of 247.5 mV was achieved in sample of Cu/Sn mole ratio of 2/1.2, which is comparable with early reported value of Voc. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:07.574195-05:
      DOI: 10.1002/pssc.201400269
       
  • Effects of H2S annealing on Cu‐Sn‐S thin films prepared from
           vacuum‐evaporated Cu‐Sn precursor
    • Authors: Yuji Miyata; Shigeyuki Nakamura, Yoji Akaki
      Pages: 765 - 768
      Abstract: In this work, Cu‐Sn‐S thin films were prepared from a vacuum‐evaporated Cu‐Sn precursor via annealing in H2S from 200 to 500 °C for 1 h. Cu2SnS3 thin films with monoclinic and tetragonal structures were observed by X‐ray diffraction when the annealing temperature exceeded 325 °C. In addition, the SnS phase was observed when the annealing temperature exceeded 275 °C. The surface of the Cu‐Sn‐S thin film annealed at 500 °C was uneven due to the re‐evaporation of SnS. The absorption coefficient of the Cu‐Sn‐S thin films was above 104 cm‐1 with energies above 1.0 eV. The band gap of these films was estimated from transmission and reflection apectra using UV‐visible‐NIR spectrophotometry to be between 0.88‐1.0 eV when the annealing temperature exceeded 450 °C. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:17.372572-05:
      DOI: 10.1002/pssc.201400310
       
  • Improvement of In2S3/ZnCuInS2 interfaces for wide‐gap solar cells
    • Authors: Teruaki Yamamoto; Takayuki Negami, Koji Matsubara, Shigeru Niki
      Pages: 769 - 772
      Abstract: We have fabricated superstrate In2S3/ZnCuInS2 (Zn2xCu1‐xIn1‐xS2, ZCIS) solar cells as the top cell of multi‐junction solar cells. The ZCIS and In2S3 thin films were deposited by spray pyrolysis deposition (SPD) and an efficiency of 4.4% was achieved with bandgap of 1.8 eV. However, in the structure of superstrate type solar cells, interdiffusion have been caused between the buffer layer and the ZCIS layer. In order to suppress the interdiffusion, we have fabricated In2S3/ZCIS substrate type solar cells. The thickness of the interdiffusion region decreased from 70 nm of the superstrate cell to 15 nm of the substrate cell. As a result, the substrate cell with bandgap of 1.8 eV showed VOC of 0.71 V and FF of 0.55 higher than those of the superstrate cells. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:18.33856-05:0
      DOI: 10.1002/pssc.201400313
       
  • Electrical performance of the InGaP solar cell irradiated with low energy
           electron beams
    • Authors: Yasuki Okuno; Shuichi Okuda, Takeo Kojima, Takashi Oka, Shirou Kawakita, Mitsuru Imaizumi, Hiroaki Kusawake
      Pages: 773 - 776
      Abstract: The investigation of the radiation degradation characteristics of InGaP space solar cells is important. In order to understand the mechanism of the degradation by radiation the samples of the InGaP solar cell were irradiated in vacuum and at ambient temperature with electron beams from a Cockcroft‐Walton type accelerator at Osaka Prefecture University. The threshold energies for recoil were obtained by theoretical calculation. The energies and the fluences of the electron beams were from 60 to 400 keV and from 3×1014 to 3×1016 cm‐2, respectively. The light‐current‐voltage measurements were performed. The degradation of Isc caused by the defects related to the phosphorus atoms was observed and the degradation was suppressed by irradiation at an energy higher than the threshold energy for recoiling Indium atoms. At an energy of 60 keV, where the recoil does not occur, the Voc was degraded. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:44.782389-05:
      DOI: 10.1002/pssc.201400322
       
  • Graphene transparent electrode for thin‐film solar cells
    • Authors: Ryousuke Ishikawa; Yasuyoshi Kurokawa, Shinsuke Miyajima, Makoto Konagai
      Pages: 777 - 780
      Abstract: Transparent electrode is a key component in the multi‐junction solar cells, working as window and intermediate electrodes. It requires high transparency for wide range and suitable electrical junctions. Graphene, a single atomic layer of sp2 graphitic carbon, is one of alternative materials. We demonstrated a‐Si thin film solar cells with high‐quality graphene grown by chemical vapor deposition. The graphene‐cell showed higher open‐circuit voltage compared with conventional transparent conductive oxide. It might be a contribution of lower Schottky barrier at graphene/p‐layer interface. Our experimental results demonstrated a high potential of graphene transparent electrode not only for a‐Si solar cells but also for multi‐junction solar cells.
      PubDate: 2015-04-09T04:43:45.860732-05:
      DOI: 10.1002/pssc.201400320
       
  • Structure and optical properties of CdS:O films by cathode sputtering
    • Authors: Masahiro Nakajima; Ryo Asaba, Akinori Suzuki, Yong‐Gu Shim, Kazuki Wakita, Kh. Khalilova, Nazim Mamedov, Ayaz Bayramov, Emil Huseynov
      Pages: 781 - 784
      Abstract: We have studied the structure and optical properties of CdS:O films deposited on SLG (soda lime glass) substrates by cathode sputtering in the atmosphere of oxygen/argon gases. According to X‐ray diffraction (XRD) and confocal Raman scattering data, the films annealed in vacuum at temperatures above 300 °C exhibited crystalline structure of CdS. On the other hand, XRD, confocal Raman scattering, AFM (atomic force microscopy) and TEM (transmission electron microscopy) data indicated amorphous structure nano‐crystallization in CdS:O films annealed in vacuum at 400 °C. For the films, the emissions located at 3.35 eV were evident from photoluminescence measurements. The origin of this energy gap is discussed by taking into account redistribution of electronic density of states in the amorphous phase and quantum‐size effect. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:14.194475-05:
      DOI: 10.1002/pssc.201400347
       
  • Fabrication of visible‐light transparent solar cells composed of
           NiO/NixZn1‐xO/ZnO heterostructures
    • Authors: Daisuke Kawade; Kazuma Moriyama, Fumika Nakamura, Shigefusa F. Chichibu, Mutsumi Sugiyama
      Pages: 785 - 788
      Abstract: Visible‐light transparent solar cells were fabricated using p ‐type NiO and n ‐type ZnO by conventional RF reactive sputtering with NiZnO alloy as an intrinsic interlayer. The energy band diagrams of NiO/NiZnO/ZnO heterojunctions were revealed by photoelectron yield spectroscopy, and the band gap energies were estimated to be 1.2 eV for NiO/Ni0.4Zn0.6O and 0.6 eV for Ni0.4Zn0.6O/ZnO heterojunctions. By using In2O3:Sn (ITO) as a transparent electrode in NiO‐based visible‐light transparent solar cells, a small but noticeable photovoltaic effect was obtained. The short‐circuit current density (Jsc) increased from 4 μA/cm2 to 12 μA/cm2 due to the insertion of Ni0.4Zn0.6O interlayer. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:18.086297-05:
      DOI: 10.1002/pssc.201400256
       
  • Variable range hopping conductivity at low temperatures in CuGaS2 single
           crystals
    • Authors: N. A. Abdullayev; Kh. V. Aliquliyeva, I. Qasimoglu, T. G. Kerimova, I. A. Mamedova
      Pages: 789 - 792
      Abstract: Charge transport mechanism in the CuGaS2 single crystals in a wide temperature range 4.3‐300 K are investigated. In the high temperature range 100‐300 K, the electrical conductivity is predominantly provided by thermally excited impurity charge carriers in the allowed energy band. The activation energy for impurity charge carriers in this temperature range is equal to 12 meV. In the low temperature range (T < 100 K), the electrical conductivity occurs through charge carrier hopping between localized states lying in a narrow energy band near the Fermi level (so called Mott conductivity). The density of localized states near the Fermi level, the width of the optimum energy band of localized levels, concentration of localized states and the average carrier‐hopping distances are estimated for different temperatures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:21.491314-05:
      DOI: 10.1002/pssc.201400339
       
  • Synthesis of SrGa2S4:Eu green emitting phosphor using liquid phase process
    • Authors: Hiroko Kominami; Yoichiro Nakanishi, Kazuhiko Hara
      Pages: 801 - 804
      Abstract: The synthesis process of sulfide phosphors using liquid phase reaction was investigated to aim at fine particle. SrGa2S4:Eu green emitting phosphor was prepared using chlorides and sodium sulfide as source materials. After chemical reaction of acid and alkali, obtained sediments were fired in sulfur atmosphere. The powders were determined at SrGa2S4 single phase by X‐ray diffraction measurement, and the obtained phosphor showed green emission of SrGa2S4:Eu excited by 325 nm of He‐Cd laser and EB excitation. It indicates that it is possibility of new synthesis method for fine‐particle sulfide phosphors. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:15.877114-05:
      DOI: 10.1002/pssc.201400282
       
  • Preparation and photoluminescence properties of Mn‐doped deep red
           emitting phosphor under blue to near ultraviolet excitations
    • Authors: Shoma Kawakita; Hiroko Kominami, Kazuhiko Hara
      Pages: 805 - 808
      Abstract: Preparation method and photoluminescence properties of Mg2(Ti0.99‐x ‐y, Gex, Siy)O4:Mn phosphor for white LED was studied. The obtained powders showed deep red emission around 670 nm under blue light excitation. The PL intensity depended on the ratio of IV atoms, and PL spectra depended on the IV atom consisted in the phosphors. It was found that the ternary or multinary compounds showed higher luminescence. It indicates that the properties of Mg2(Ti0.99‐x, Gex)O4:Mn might much improve by preparation of completed alloy. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:10.833397-05:
      DOI: 10.1002/pssc.201400323
       
  • Blue phosphor synthesized with Eu‐containing strontium aluminate by
           reaction on single crystalline magnesia
    • Authors: Keiji Komatsu; Atsushi Nakamura, Ariyuki Kato, Shigeo Ohshio, Hidetoshi Saitoh
      Pages: 809 - 813
      Abstract: The luminescence properties of strontium aluminate (Sr‐Al‐O) phosphors change strongly depending on the starting metal composition ratio of strontium oxide (SrO) and alumina (Al2O3). In this study, the starting metal composition effect on blue Sr‐Al‐O:Eu2+ phosphor synthesized on single crystalline magnesia (MgO) was investigated. The crystal structure and the emission property of the obtained Sr‐Al‐O:Eu2+ blue phosphors, were independent of the Al2O3/SrO ratio in the raw material. In addition, the obtained emission phases were not contained Al atom. These results indicated the correct starting metal composition for the blue phosphor synthesized on MgO is SrO:Eu. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:10:13.478997-05:
      DOI: 10.1002/pssc.201400304
       
  • First‐principles study of doping properties in ZnSnAs2
    • Authors: Masato Ishikawa; Takashi Nakayama
      Pages: 814 - 817
      Abstract: Doping properties in ZnSnAs2 compound semiconductors were studied by the first‐principles spin‐polarized calculation. We have shown that the Ga doping into Zn site produces an ideal n‐type system with small effective mass, not sensitive to the doping concentration, which feature merits the optical isolator application. On the other hand, the Mn doping into Sn site induces a large spin moment around S=1, which merits the spintronics application. When the Mn concentration is increased, however, Mn atoms prefer to locate nearby and the spin moment decreases by the anti‐ferromagnetic interaction between Mn atoms. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:30:08.788846-05:
      DOI: 10.1002/pssc.201400277
       
  • Electronic structure of BaFeO3 studied by X‐ray spectroscopy
    • Authors: Masaichiro Mizumaki; Hitoshi Fujii, Kenji Yoshii, Naoaki Hayashi, Takashi Saito, Yuichi Shimakawa, Takayuki Uozumi, Mikio Takano
      Pages: 818 - 821
      Abstract: We investigated the electronic structure of BaFeO3 by using HAXPES and XAS measurements and first principle studies. The experimental and theoretical results indicated that BaFeO3 is a negative charge transfer compound. We concluded that the on‐site Coulomb energy and the strong hybridization between Fe‐3d and O‐2p orbitals play a very important role of emergence of negative charge transfer. And we found the new structure in the Fe‐2p XPS spectrum and concluded this structure is originated from non‐local screening. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:10.652037-05:
      DOI: 10.1002/pssc.201400252
       
  • Metallic conductivity and weak antilocalization in Bi2Te2.7Se0.3 thin
           films
    • Authors: Nadir A. Abdullayev; Afet M. Kerimova, Khayala V. Aliquliyeva, Yong Gu Shim, Kojiro Mimura, Kazuki Wakita, Oktay Z. Alekperov, Nazim T. Mamedov, Vladimir N. Zverev
      Pages: 822 - 825
      Abstract: Submicron thin films of Bi2Te2,7Se0,3 solid solution is synthesized by thermal vacuum evaporation. The films are then subjected to after‐growth vacuum annealing and characterized using X‐ray diffraction and confocal laser microscopy techniques. Electron transport in the synthesized films is studied over the temperature range of 1.4‐300 K at magnetic fields up to 8 T. Electron localization due to electron‐electron interaction, along with weak anti‐localization effect at weak magnetic fields and temperatures below 8 K is observed. The latter effect is commonly encountered in thin films of topological insulators grown by molecular beam epitaxy and has therefore been ascribed to the manifestation of the topological surface states. Finally, phase coherence length is estimated.
      PubDate: 2015-04-22T05:30:20.305072-05:
      DOI: 10.1002/pssc.201400338
       
  • Temperature dependence of low‐frequency optical phonons in TlInS2
    • Authors: Raul Paucar; YongGu Shim, Kazuki Wakita, Oktay Alekperov, Nazim Mamedov
      Pages: 826 - 829
      Abstract: The unpolarized Stocks component of the Raman spectra of the layered ternary thallium dichalcogenide, TlInS2 was studied with the aid of a Raman confocal microscope system in the low‐frequency region of 35‐150 cm‐1 over the temperature range that embraced the region of the successive phase transitions in this crystal. The observed spectra were deconvoluted into Lorentzian peaks to single‐out the contribution of each Raman mode. The temperature dependence of the Raman frequency and broadening associated with each mode was then obtained. The irregular temperature behaviour of most modes was disclosed in the proximity of phase transitions. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:16.347173-05:
      DOI: 10.1002/pssc.201400350
       
  • Excitonic emission of TlGaSe2
    • Authors: Masashi Hagiwara; Raul Paucar, YongGu Shim, Kazuki Wakita, Oktay Alekperov, Arzu Najafov, Nazim Mamedov
      Pages: 830 - 833
      Abstract: Photoluminescence (PL) spectra in the band‐edge region of bulk single‐crystals of layered ternary chalcogenide TlGaSe2 were examined at low temperature using confocal microscopy. Obvious PL emission near the band‐edge region appeared only when the excitation light travelled in the direction normal to the c axis of the crystal structure of TlGaSe2. The observed PL spectra were resolved into two Gaussian peaks, A and B, located at 2.01 and 2.10 eV, respectively. By analyzing the excitation intensity dependence of the PL intensity, we assigned peak B to proper free excitons, whereas peak A seems to represent free excitons derived from the distorted crystal structure of TlGaSe2. This is the first observation of free excitons in TlGaSe2 by PL measurement. We also examined the temperature dependence of the PL intensity. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-09T04:43:51.068226-05:
      DOI: 10.1002/pssc.201400348
       
  • Phonon‐phonon interaction in CdGa2Se2 single crystals
    • Authors: T. G. Kerimova; N. A. Abdullayev, L. Y. Kengerlinski, I. A. Mamedova, N. I. Ibragimov
      Pages: 834 - 836
      Abstract: Raman scattering spectra of CdGa2Se4 single crystals were measured in temperature range 8‐300 K. From the temperature dependence of optical phonons of B (196 cm‐1) and E (246 cm‐1) symmetry type, the lattice deformation and phonon‐phonon interaction contributions to the temperature coefficient of phonon shift were calculated. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-14T06:20:06.305425-05:
      DOI: 10.1002/pssc.201400344
       
  • Preparation of europium‐doped GaN and AlGaN films grown by
           radical‐nitrogen‐assisted compound‐source MBE
    • Authors: Shinji Yudate; Yuki Koyama, Sho Shirakata
      Pages: 837 - 840
      Abstract: By the compound‐source molecular beam epitaxy (CS‐MBE), GaN:Eu and AlGaN films grown on both Al2O3(0001) and GaAs(100) substrates were prepared. Under RHEED observation, streak RHEED patterns from GaN were observed. This result shows that the surface of the film grown by CS‐MBE is atomically flat. From the XRD measurements, for GaN:Eu/Al2O3(0001), the film was oriented to c‐axis. On the other hands, for GaN:Eu/GaAs(100), the layer includes both the hexagonal and cubic phases. From the PL measurements, the PL spectra of both GaN:Eu/Al2O3 and GaN:Eu/GaAs(100) showed PL peaks related to Eu3+ ion. For GaN:Eu/GaAs(100), it is possible that part of Eu atom incorporates cubic‐GaN site (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-04-22T05:30:19.298999-05:
      DOI: 10.1002/pssc.201400330
       
  • Elemental substitution effects in multiferroic R Fe2O4 (R: rare earths)
    • Authors: Kenji Yoshii; Takashi Funae, Masaichiro Mizumaki, Hiroki Ejiri, Naoshi Ikeda, Hiroyuki Saitoh, Daiju Matsumura
      Pages: 841 - 844
      Abstract: We report the effects of elemental substitutions in multiferroic R Fe2O4 (R: Y, Ho‐Lu, In). The substitution by nonmagnetic Ga3+ at the Fe site, which has not been reported so far, shows a drastic decrease in the ferrimagnetic transition temperature (TN). This is plausibly owing to the suppression of magnetic interactions between Fe ions, based on our previous results of other substituted systems such as R FeCoO4. Dielectric constants near room temperature were comparable to those of R Fe2O4. The suppression of dielectric loss in this system is suitable to application. The R ‐site substitution was also attempted by the large R3+ ions such as Dy3+. The solubility limit was up to ∼10% of R ions. TN was raised by 5‐10 K for Dy3+ substitution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:18.986054-05:
      DOI: 10.1002/pssc.201400250
       
  • Optical band gap of Li8SiN4 with disordered structure as a cathode
           material of lithium secondary batteries
    • Authors: T. Yamashita; S. Kuwano, K. Kuriyama, K. Kushida
      Pages: 845 - 848
      Abstract: The band gap of and disordered structure in Li8SiN4 (lattice constant: a = 10.148 Å, c = 9.567 Å) are studied by optical absorption, photoacoustic spectroscopy, X‐ray diffraction, and Raman scattering spectroscopy. Li8SiN4 is a semiconductor with a band gap of 2.4 eV, suggesting the transition from the N‐2p valence band to the conduction band mainly consisting of Si‐3s and/or ‐3p orbitals. A broad Raman peak is observed at 586 cm–1, indicating the homogenously random distribution of Li and Si atoms. Li8SiN4 crystallizes in a superstructure of eight face‐centered N sublattices. In each sublattice, one Li and one Si atom are randomly and diagonally occupied at two tetrahedral sites next to N, while six Li atoms reside at the other sites next to N. The possible locations of one remaining Li atom are also discussed. Li8SiN4 is a direct transition, which is slightly larger than the d‐d electron transitions in the typical cathode materials LiMn2O4 and LiCoO2. For a 5 × 5 mm2 sized lithium secondary battery with the Li8SiN4 + acetylene black cathode/propylene carbonate + LiClO4 electrolyte/Li anode structure, the capacity for the discharge current of 10 µA is between 2.44 µAh/cm2 and 3.56 µAh/cm2 for a potential range between 2.8 V and 3.8 V. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-03-30T02:20:14.57373-05:0
      DOI: 10.1002/pssc.201400214
       
  • Numerical analysis of light elements transport in a unidirectional
           solidification furnace
    • Authors: Koichi Kakimoto; Bing Gao, Satoshi Nakano
      Abstract: Quantitative study of light elements such as carbon and oxygen in multi‐crystalline silicon for solar cells is required to grow crystals with high quality. The transport of both carbon and oxygen is one of the critical issues to increase efficiency of solar cells made of silicon materials. Concentrations of carbon and oxygen in a furnace affect each others, therefore it is important to control mass transfer of carbon and oxygen in a furnace. Numerical calculation with a chemical reaction between carbon and oxygen was carried out to study how both light impurities are incorporated into crystals through the melt and gas during solidification process. The effects of flow rate and pressure on the impurities were examined. An increase in the flow rate can reduce both carbon and oxygen impurities in the crystal, though the reduction of carbon is more obvious. An increase in gas pressure can also obviously reduce the oxygen impurity but has only a small effect on the carbon impurity (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2010-11-15T04:22:05.648279-05:
      DOI: 10.1002/pssc.200900117
       
 
 
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