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  Subjects -> PHYSICS (Total: 793 journals)
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PHYSICS (572 journals)            First | 1 2 3 4 5 6 | Last

Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 22)
Natural Science     Open Access   (Followers: 9)
Nature Communications     Open Access   (Followers: 88)
Nature Materials     Full-text available via subscription   (Followers: 58)
Nature Physics     Full-text available via subscription   (Followers: 29)
NDT & E International     Hybrid Journal   (Followers: 25)
Neutron News     Hybrid Journal  
New Journal of Physics     Open Access   (Followers: 5)
Niels Bohr Collected Works     Full-text available via subscription  
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: 11)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 3)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 9)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 5)
Open Journal of Microphysics     Open Access  
Open Physics     Open Access   (Followers: 2)
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 7)
Optofluidics, Microfluidics and Nanofluidics     Open Access   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 5)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 13)
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: 5)
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: 20)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 9)
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: 3)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 1)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 2)
Physics and Materials Chemistry     Open Access   (Followers: 1)
Physics Essays     Full-text available via subscription   (Followers: 1)
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: 11)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 30)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 7)
Physics of the Dark Universe     Open Access   (Followers: 1)
Physics of the Solid State     Hybrid Journal   (Followers: 2)
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: 38)
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: 2)
Plasma Physics Reports     Hybrid Journal   (Followers: 1)
Pramana     Open Access   (Followers: 10)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 471)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 22)
Progress in Planning     Hybrid Journal  
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: 2)
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: 4)
Radiological Physics and Technology     Hybrid Journal   (Followers: 2)
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: 19)

  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  [1597 journals]
  • Constructive feedback for the growth of laser‐induced periodic
           surface structures
    • Abstract: We study the formation and growth of laser‐induced periodic surface structures (LIPSSs) with the finite‐difference time‐domain (FDTD) method. We use a recently proposed inter‐pulse feedback method to account for the evolution of the surface morphology between each laser pulse sent to the surface of the processed material. This method has been used with an ablation‐like mechanism, by removing material exposed to a light intensity higher than a given threshold. We propose an inverse mechanism, an expansion‐like mechanism, able to grow structures that the ablation‐like process cannot. This allows us to introduce the notions of constructive and destructive feedback and explains a strong contradiction between the standard Sipe‐Drude theory and the experimental observations, i.e. the formation on metals of structures usually linked to wide band gap dielectrics.
      PubDate: 2016-01-29T05:30:23.030817-05:
      DOI: 10.1002/pssc.201510146
       
  • Stabilization of silicon nanoparticles in colloidal solutions
    • Abstract: Silicon nanoparticles, apart from their potential use in optoelectronics or photovoltaics, are very promising also for biological applications. Typical requirements for such nanoparticles used in biological research differ from that for optoelectronics ‐ the aim is to prepare aqueous or isotonic (such as phosphate buffered saline ‐ PBS) colloidal solutions of stable, uniform and strongly luminescing nanoparticles, with sizes suitable for the process of cell endocytosis, ideally in the range of tens to hundreds of nanometers. We have prepared colloidal solutions of luminescing porous silicon nanoparticles (size around 100 nm) obtained by electrochemical etching of silicon wafers. Adding hydrogen peroxide to the etching bath results in oxidized nanoparticle surface and hydrophilic behavior. However, the as‐prepared samples agglomerate – the dynamic light scattering revealed the increase of the agglomerates size from 60 nm in fresh samples to 400 nm in one‐month‐old samples. The tendency to agglomerate was confirmed by zeta‐potential measurements. The first attempt to steric stabilization by bovine serum albumin, glycine, glutamic acid and dextran is presented, where the increased stability was observed in the glycine‐ terminated samples. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:22.143788-05:
      DOI: 10.1002/pssc.201510217
       
  • Study of threshold voltage instability in E‐mode GaN MOS‐HEMTs
    • Authors: Ferdinando Iucolano; Antonino Parisi, Santo Reina, G. Meneghesso, Alessandro Chini
      Abstract: In this work, the threshold instability in E‐mode GaN MOS‐HEMTs was investigated. In particular, the shift of VTH as a function of the applied positive gate voltage during device characterization was monitored, resulting in positive VTH shifts up to 1 V. A complete VTH recovery required more than one day of unbiased storage, but a partial recovery of the observed VTH shift was observed after few seconds. These results could be related to different positions of trap states: fast states, localized at the dielectric/GaN interface and slow states, the traps inside the dielectric layer. Moreover, VTH shift of 0.2 and 0.8 V for fast and slow states, respectively, was obtained. To gain insight into the physical mechanism involved in the observed phenomena, numerical simulation were also carried out. A VTH shift was obtained adding the interface states. Moreover, three different distributions of traps were compared. In particular, the concentration of filled traps was monitored to understand the impact of the distribution on the electrical behaviour. An increment in filled trap concentration at the increasing of the applied VGS, which in turns correlates with experimentally evaluated device behaviour, was obtained if the distribution of traps states is also above the GaN conduction band energy. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:21.177644-05:
      DOI: 10.1002/pssc.201510191
       
  • Investigation of breakdown properties in the carbon doped GaN by
           photoluminescence analysis
    • Authors: Deqiu Zhou; Yiqiang Ni, Zhiyuan He, Fan Yang, Yao Yao, Zhen Shen, Jian Zhong, Guilin Zhou, Yue Zheng, Liang He, Zhisheng Wu, Baijun Zhang, Yang Liu
      Abstract: The electrical and optical properties of the carbon doped GaN grown on Si substrate by metal‐organic chemical‐vapor deposition are investigated. Carbon impurity doping can improve the breakdown voltage effectively. However excess carbon in contrast depresses the breakdown voltage. This result is correlated with the carbon dopant behaviour in GaN which can be observed by analyzing the photoluminescence (PL) spectra. It is explained that the carbon impurity favours the formation of CN (carbon substitution of nitrogen) which acts as a deep level acceptor. The acceptor compensates the n‐type background impurities, which may resulting in suppressing the leakage current at high electric field, and leads to the improvement of the breakdown voltage. However, with excess carbon doping level, a significant amount of CGa (carbon substitution of gallium) form in GaN. The CGa, acting as the donor, compensates the CN and hence impairs the concentration of the deep level acceptor. In a result, the compensation of the n‐type background impurities by the deep level acceptor is curbed by the CGa‐CN self‐compensation effect, which leads to the decrease of the breakdown voltage. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:20.144927-05:
      DOI: 10.1002/pssc.201510176
       
  • Growth of compressively‐strained GaN films on Si(111) substrates
           with thick AlGaN transition and AlGaN superlattice buffer layers
    • Authors: Lei Pan; Xun Dong, Jinyu Ni, Zhonghui Li, Qiankun Yang, Daqing Peng, Chuanhao Li
      Abstract: In this paper, crack‐free GaN films with step‐graded AlGaN transition layer and AlGaN superlattice layer as buffer layers were grown on Si(111) substrate by metal‐organic chemical vapor deposition(MOCVD). The combination of both buffers effectively improves the properties of GaN layer. With the optimization of the buffer structures, high quality compressively‐strained GaN layers with thickness up to 3.6 μm have been obtained on Si(111) substrates (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:18.769418-05:
      DOI: 10.1002/pssc.201510175
       
  • Threshold voltage engineering in GaN‐based HEMT by using La2O3 gate
           dielectric
    • Authors: Minhan Mi; Yunlong He, Bin Hou, Meng Zhang, Jincheng Zhang, Chong Wang, Xiaohua Ma, Yue Hao
      Abstract: In this paper, we presented AlGaN/GaN MIS‐HEMT with a 6‐nm ALD La2O3 as gate insulator. The gate leakage current had been greatly reduced at both positive and negative bias by using La2O3 gate dielectric. Threshold voltage for MIS‐HEMT moved +1 V toward positive direction compared with the Schottky gate HEMT (HEMT) demonstrating the negatively fixed charges at La2O3/AlGaN interface. Besides, the transconductance of MIS‐HEMT was not degraded. The stability of fixed and trap state introduced by La2O3 gate dielectric was discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:17.823511-05:
      DOI: 10.1002/pssc.201510174
       
  • Effect of an ITO current spreading layer on the performance of InGaN MQW
           solar cells
    • Authors: J. Bai; M. Athanasiou, T. Wang
      Abstract: InGaN‐based solar cells have been investigated through fabrication with and without using an indium‐tin‐oxide (ITO) current spreading layer (CSL). For the devices with a planar top surface, utilization of the ITO CSL leads to enhanced performance under 1 sun air‐mass 1.5 global spectrum illumination. In contrast, when surface‐texturing is applied to significantly improve the light absorption, the efficiency of the device without using the ITO CSL is higher compared to the one with the ITO. Furthermore, measurements on reflectance of the corresponding surfaces and transmission of the ITO CSL are carried out. The influence of the ITO CSL has been discussed in terms of surface reflection, the light loss due to the ITO CSL shading and the power loss associated with the absence of the ITO CSL. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:16.951925-05:
      DOI: 10.1002/pssc.201510171
       
  • Modulation of the domain mode in GaN‐based planar Gunn diode for
           terahertz applications
    • Abstract: This paper reports the modulation of the domain mode in the 2DEG channel of GaN HEMT‐like Gunn diodes by adjustment the electron concentration of the 2DEG near the cathode side. The enhancement of the electron concentration near the cathode side promotes the fast formation of the dipole domain layer and greatly reduces the dead zone length, which increases the RF output power. The employment of the recess layer near the cathode reduces the electron concentration of the 2DEG beneath it, which acts as a notch‐doped layer as in the bulk vertical diode. The reduction of the electron concentration of the 2DEG near the cathode promotes the formation of dual‐domain in one oscillation circle, which aims to enhance harmonic components of Gunn oscillation so as to minimize the use of frequency multipliers for SMMW and THz operation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-29T05:30:16.036956-05:
      DOI: 10.1002/pssc.201510158
       
  • MOCVD growth of DH‐HEMT buffers with low‐temperature AlN
           
    • Authors: Ming Zhao; Hu Liang, Prem Kumar Kandaswamy, Marleen Van Hove, Rafael Venegas, Evi Vranken, Paola Favia, Annelies Vanderheyden, Danielle Vanhaeren, Yoga Nrusimha Saripalli, Stefaan Decoutere, Robert Langer
      Abstract: In this work, we have systematically investigated the technique of low‐temperature AlN interlayer in MOCVD growth of double heterojunction high‐electron‐mobility transistors buffer stacks on 200 mm Si (111) substrates. We have demonstrated that a continuous compressive stress can be maintained by insertion of interlayers which compensated a large tensile stress during cooling for a thick buffer. This eventually led to a low wafer bow and a good surface quality that enabled wafers with full device stack meeting the specifications for processing in our 200 mm CMOS pilot line. We also demonstrated at both forward and reverse bias conditions a significantly improved vertical buffer breakdown voltage (which is defined at a leakage current of 1 µA/mm2 in the present work) of >500 V at 25 °C and >300 V at 150 °C, respectively. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:12.021243-05:
      DOI: 10.1002/pssc.201510280
       
  • Semi‐polar (11‐22) GaN grown on patterned (113) Si substrate
    • Authors: Xiang Yu; Yaonan Hou, Shuoheng Shen, Jie Bai, Yipin Gong, Yun Zhang, Tao Wang
      Abstract: An epitaxial growth technic has been developed to synthesize semi‐polar (11‐22) GaN on (113) Si substrate with inverted‐pyramid patterns. The reaction between Ga and Si substrate has been successfully solved by simply depositing a thin SiO2 layer on selective regions of the substrate before growth. High quality semi‐polar (11‐22) GaN‐on‐Si with a smooth surface has been obtained after delicately tuning growth conditions. Based on the scanning electron microscopy and x‐ray diffraction characterizations, a model has been well established to illuminate the growth process. Due to the very low density of defects confirmed by transmission electron microscopy, our sample demonstrates an excellent optical property, which is promising for efficient optoelectronic devices using GaN‐on‐Si configuration. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:10.97402-05:0
      DOI: 10.1002/pssc.201510209
       
  • Temperature dependence of GaN MOS capacitor characteristics
    • Authors: Zhibo Guo; Ke Tang, T. Paul Chow
      Abstract: GaN MOS capacitors on both as‐grown and dry/wet‐etched GaN surfaces are characterized by C‐V and G‐ω measurements at elevated temperatures. The nature of GaN/SiO2 interface traps are determined in detail by extracting interface trap density, surface potential fluctuation, trap time constant and capture cross‐section. When temperature increases, trap time constant decreases so that more traps become active and contribute to observed higher interface trap density, especially for traps at deeper energy levels. The deeper trap levels activated at higher temperatures also induce corresponding temperature‐dependent surface potential fluctuation variations. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:10.047019-05:
      DOI: 10.1002/pssc.201510201
       
  • Comparison of silicon, SiC and GaN power transistor technologies with
           breakdown voltage rating from 1.2 kV to 15 kV
    • Authors: Sauvik Chowdhury; Zhibo Guo, Xueqing Liu, T. Paul Chow
      Abstract: In recent years, different power transistors have been developed in silicon carbide (SiC) and gallium nitride (GaN) as replacements for silicon based IGBTs. This paper presents a simulation comparison of the static and dynamic performance of silicon IGBTs with different SiC and GaN based lateral and vertical power transistors (HEMT, MOSFET and IGBT) with breakdown voltage ratings between 1.2 kV to 15 kV. The strengths and weaknesses of different technologies which make them suitable at different voltage levels have been discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:09.141018-05:
      DOI: 10.1002/pssc.201510200
       
  • Model of photoluminescence temperature dependence in GaN/AlN quantum dot
           structures
    • Authors: Ivan A. Aleksandrov; Vladimir G. Mansurov, Vladimir I. Vdovin, Konstantin S. Zhuravlev
      Abstract: Temperature dependence of photoluminescence intensity and lifetime of GaN/AlN quantum dots have been investigated and compared a theoretical model. Experimental photoluminescence lifetime is mainly determined by radiative process at low temperatures, but somewhat differs from the calculated radiative lifetime at room temperature. This difference corresponds to decrease in the nonradiative lifetime with temperature. Dependence of the nonradiative lifetime in GaN/AlN quantum dots on temperature and emission wavelength has been described by calculations assuming that the nonradiative recombination is caused by tunneling of carriers from quantum dots to nonradiative recombination centers. The tunneling probability has been calculated in the configuration coordinate model using the zero‐radius potential approximation. Temperature dependence of photoluminescence intensity of quantum dots does not follow the temperature dependence of the ratio of the photoluminescence lifetime to the radiative lifetime. Nonradiative recombination of carriers generated in a wetting layer has been taken into account to describe the temperature dependence of the photoluminescence intensity. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:08.227658-05:
      DOI: 10.1002/pssc.201510199
       
  • Theoretical analysis of the influence of band tail defects on PIN InGaN
           solar cells
    • Authors: Baozhu Wang; Yan Feng, Lizhi Meng, Min Wang, Hongling Xiao, Xiaoliang Wang
      Abstract: InGaN solar cells have higher conversion efficiency than traditional Si based solar cells. However, efficiency of experimental InGaN solar cell is lower than expected. There are still several problems, such as the structure design of InGaN solar cells, the quality of InGaN materials, need to be discussed and solved. Thus, the researches of structure design and defect effects are important for the implications of InGaN solar cells. The performance of p‐GaN/i‐InxGa1–x/n‐GaN solar cells with different In content is simulated by AMPS‐1D. It is found that the optimum efficiency of p‐GaN/i‐InxGa1–xN/n‐GaN solar cells is 8.9% when the In content is 0.26. The p‐GaN/i‐In0.26Ga0.74/n‐GaN solar cells with band tail defects are simulated. The simulated results show the efficiency decreases with the increase of the E‐character. And the efficiency decreases sharply from 8.30% to 7.19% when the capture cross section is 10–14 cm–2. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:40:07.095308-05:
      DOI: 10.1002/pssc.201510198
       
  • High‐resistance GaN‐based buffer layers grown by a
           polarization doping method
    • Authors: Lian Zhang; Yun Zhang, Hongxi Lu, Junxi Wang, Jinmin Li
      Abstract: A high‐resistance buffer layer is critical for GaN‐based high electron mobility transistors (HEMTs) to suppress the drain leakage current and pre‐mature device breakdown. A typical method to obtain the HR buffer layers is the acceptor impurity doping that is able to provide holes to compensate the background electrons in the buffer layers. However, the intentional doped acceptor impurities such as Mg, Fe and C will result in current collapse in GaN‐based HEMTs. To address this issue, in this work, we employed a polarization doping method of holes by Al‐composition grading instead of the acceptor impurity doping. The sheet resistance of the GaN‐based buffer layer significantly increased due to the holes generated by the polarization field. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:30:08.801667-05:
      DOI: 10.1002/pssc.201510181
       
  • Room temperature PL efficiency of InGaN/GaN quantum well structures with
           prelayers as a function of number of quantum wells
    • Abstract: We report on the effects of varying the number of quantum wells (QWs) in an InGaN/GaN multiple QW (MQW) structure containing a 23 nm thick In0.05Ga0.95N prelayer doped with Si. The calculated conduction and valence bands for the structures show an increasing total electric field across the QWs with increasing number of QWs. This is due to the reduced strength of the surface polarisation field, which opposes the built‐in field across the QWs, as its range is increased over thicker samples. Low temperature photoluminescence (PL) measurements show a red shifted QW emission peak energy, which is attributed to the enhanced quantum confined Stark effect with increasing total field strength across the QWs. Low temperature PL time decay measurements and room temperature internal quantum efficiency (IQE) measurements show decreasing radiative recombination rates and decreasing IQE, respectively, with increasing number of QWs. These are attributed to the increased spatial separation of the electron and hole wavefunctions, consistent with the calculated band profiles. It is also shown that, for samples with fewer QWs, the reduction of the total field across the QWs makes the radiative recombination rate sufficiently fast that it is competitive with the efficiency losses associated with the thermal escape of carriers. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-27T02:30:07.492639-05:
      DOI: 10.1002/pssc.201510180
       
  • Cover Picture: Phys. Status Solidi C 1/2016
    • Abstract: The authors present in their paper on pp. 8–12 the recrystallization of polycrystalline SnS in different molten salts CdI2, SnCl2 and KI as flux materials. The recrystallization and growth of polycrystalline material in molten salts produces unique SnS monograin powders usable in monograin layer solar cells. The compositional and structural analysis showed that single phase SnS monograin powder can be obtained at 740 °C in KI and at 500 °C in SnCl2. Recrystallization of SnS in molten CdI2 resulted in multiphase mixture of SnS, Sn2S3 and CdS crystals due to chemical interactions between the compounds. The morphology of crystals was controlled by the nature of the used flux materials: needle‐like Sn2S3 together with round edged crystals of CdS were grown in CdI2. Smooth flat crystals of SnS in SnCl2 and well‐formed SnS crystals with rounded edges in KI had been gained. Thermal analyses revealed that phase transition from α‐SnS to β‐SnS occurs in the temperature region 592–596 °C depending on the used flux.
      PubDate: 2016-01-26T06:15:09.456251-05:
      DOI: 10.1002/pssc.201670109
       
  • Issue Information: Phys. Status Solidi C 1/2016
    • PubDate: 2016-01-26T06:15:08.802869-05:
      DOI: 10.1002/pssc.201670110
       
  • Diamond‐SAW devices: a reverse fabrication method
    • Abstract: Surface acoustic wave (SAW) devices are key components in modern wireless communication systems. Besides being used as reflective delay lines, filters or resonators, SAW devices can be used as sensors and fixed‐code identification tags. Due to their high‐acoustic velo‐city, diamond films can be combined with piezoelectric materials to fabricate diamond‐based SAW devices with potential for high frequency applications. This paper presents results of coating commercial SAW delay lines with diamond films. The films were deposited on lithium niobate under different conditions in a hot filament chemical vapour deposition system. Seeding was performed using 6‐12 μm diamond grit and 20‐30 nm nano‐diamond particles based suspensions. After tuning the deposition conditions, dies of 74 MHz delay lines were coated with diamond. The quality, morphology and conformability of the coatings were evaluated by scanning electron microscopy (SEM) and Raman spectroscopy. The integrity of the interdigitated transducers (IDTs) after deposition was evaluated by SEM. S‐parameters of as‐bought and diamond‐coated dies were measured using a network analyser. Although the frequency response is attenuated after diamond deposition, integrity of the IDTs and the operating principle of the devices are kept intact. These preliminary results open the door to a simplified fabrication procedure of diamond‐based SAW devices. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-08T06:10:28.235738-05:
      DOI: 10.1002/pssc.201510313
       
  • pss – taking legacy to the future
    • Authors: Sabine Bahrs; Nadezda Panarina, Stefan Hildebrandt
      Pages: 3 - 4
      Abstract: Dear readers, 2016 has a special anniversary coming up for physica status solidi (pss): Its most‐ever‐cited article “Optical Properties and Electronic Structure of Amorphous Germanium” by J. Tauc, R. Grigorovici, and A. Vancu (then Prague and Bucharest) was published half a century ago [1]. Printed about two months after receipt of the manuscript on June 1st 1966, it is a witness of the impressively fast publication times of pss back then. The article went online 40 years later in 2006, when Wiley had the pre‐internet‐era content scanned. Citations (right axis) and cumulative citations (left axis) to “Optical Properties and Electronic Structure of Amorphous Germanium” by J. Tauc et al., pss (1966) [1] versus year (Data from Web of Sci‐ence SCI, Dec 2015). Beyond the reach of contemporary journal‐usage metrics, it has been collecting citations throughout 50 years, and recently we even saw a pronounced acceleration due to renewed interest in amorphous materials, with groups analyzing and developing the method proposed by Tauc et al. further [2]. pss proudly continues to provide, promote, and safeguard this valuable piece of information, and to accompany it through the changing times of its lasting legacy for the solid state physics research community. All the while, we are working with our authors, reviewers, board members, and guest editors to add content to the journal that has the potential for a similarly impressive career in scientific literature. Much of pss ' most interesting content is attracted by specially compiled, topical publications in collaboration with guest editors these days, and we can mention only a few of them here. Prominently in 2015, pss leaned in on the recent physics Nobel Prize topic again with a double issue on Nitride Semiconductors [3], and also the January issue of pss (b) in 2016 is dedicated to the specific challenges of Polarization‐Field Control in Nitride Light Emit‐ters [4]. Regarding long‐lasting topics we should mention the “20 Years of Science for Diamond” issue in pss (a) [5], and on the contemporary device physics line both “Transparent Conductive Oxides – Fundamentals and Applications” [6] and the issue dedicated to “Advanced Materials and Nano‐ technology for Photovoltaics” [7]. Reflecting the intense activity in the field and its impact on the world energy economy, photovoltaics based on inorganic as well as organic electronics have been increasingly prominent throughout the pss journal family, also resulting in the pss (RRL) standing topical section “RRL solar”. pss (b) has a very interesting collection on the physics of low‐dimensional structures, including graphene, nanotubes, and transition‐metal dichalcogenides, in “Electronic Properties of Novel Materials: Molecular Nanostructures” [8]. Venturing into more inter‐ disciplinary areas, pss (b) also published “Auxetics and Other Systems of ‘Negative’ Characteristics” with 32 contributions from physics, mathematics, and engineering perspectives [9] and pss (a) had “Engineering of Functional Interfaces” [10]. This year we are looking forward to “Carbononics – Integrating Electronics, Photonics and Spintronics with Graphene Quantum Dots” [11], a Focus Issue in pss (RRL), and many other interesting projects. In 2015, physica status solidi (c) – current topics in solid state physics joined the other pss family journals on the editorial platform Editorial Manager. With system data on a new level of transparency, we may report for the year that pss published 1172 articles, worked with 71 guest editors and received approximately 4400 reviewer reports (including re‐reviews). As is obvious from these numbers, the journal family flourishes due to its lively interaction and the lasting strong support from the solid state researcher community. We would like to convey our sincere gratitude to all board members, guest editors, reviewers, and authors for the time and work they invest. And of course, we remain open for your future suggestions, and we will observe closely which topic may be poised to become the next pss evergreen. With best wishes for a prosperous year 2016, Sabine Bahrs, Nadezda Panarina, and Stefan Hildebrandt Editors physica status solidi
      PubDate: 2016-01-26T06:15:09.354418-05:
      DOI: 10.1002/pssc.201670111
       
  • Contents: Phys. Status Solidi C 1/2016
    • Pages: 5 - 6
      PubDate: 2016-01-26T06:15:09.510515-05:
      DOI: 10.1002/pssc.201670112
       
  • Earth abundant and emerging solar energy conversion materials
    • Pages: 7 - 7
      Abstract: This proceedings volume of physica status solidi contains research presented at the 2015 Spring European Materials Research Society Meeting in Lille, France. The papers were peer‐reviewed and selected for the proceedings. This meeting was a follow‐on from Symposium E from the Spring 2014 MRS Meeting in San Francisco (“Earth‐Abundant Inorganic Solar‐Energy Conversion”), and will be followed in 2016 with Symposium EE1 at the Spring MRS Meeting in Phoenix (“Emerging Materials and Phenomena for Solar Energy Conversion”). The symposium focused specifically on materials outside of the commercial realm (Si, CdTe and CIGS). All of the topics covered related to earth‐abundant and emerging materials, some of which include metal‐organic perovskite solar cells, novel inorganic solar absorbers, computational design for photovoltaics, defect analysis of absorber materials, interface and surface properties, and novel materials for solar fuel devices. The papers contributed to these Proceedings represent a cross‐section of some of the diverse topics covered during the symposium. We would like to thank all of the many invited and contributed speakers in the symposium, as well as those who presented posters at the meeting. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2016-01-26T06:15:09.256725-05:
      DOI: 10.1002/pssc.201670113
       
  • Two carrier localizations in GaN/AlGaN multiquantum wells investigated by
           temperature dependent photoluminescence
    • Authors: Feng Wu; Yang Li, Wu Tian, Jun Zhang, Shuai Wang, Jiangnan Dai, Zhe Chuan Feng, Changqing Chen
      Abstract: Carrier localization effect has been observed in GaN/AlGaN multiquantum wells (MQWs) by analyzing the temperature dependent photoluminescence (PL) results. Specifically, two neighbouring peaks can be seen in the PL spectra with an abnormal variation when increasing the temperature. A conduction band model with two minimal potentials corresponding to two carrier localizations is proposed to explain the PL spectra. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:20.157462-05:
      DOI: 10.1002/pssc.201510178
       
  • Comparative study on MAPbI3 based solar cells using different electron
           transporting materials
    • Abstract: This paper presents a comparative study on organometal halide perovskite based solar cells using two different transparent conducting oxides such as TiO2 and ZnO as electron transporting materials. Simulation is an interesting tool for studying the behavior of every component of a solar cell device as well as for analyzing the performance of the full device. Solar cell capacitance simulator (SCAPS)‐1D has been the tool used for numerical simulation of such devices. Influences of thickness of absorber and ETMs, interface trap density of states and dopant concentration of ETMs on the performance of photovoltaic solar cells are studied. Comparable efficiencies of 22.35% and 22.49% for PV devices made of spiro‐MeOTAD/MAPbI3/TiO2 and spiro‐MeOTAD/MAPbI3/ZnO, respectively, with 400/400/90 nm thicknesses under 1 Sun illumination are observed. The performance of both devices indicates the replacement of the TiO2 by a ZnO layer. It could be a good option to reduce the cost and increase the mobility of ETM for this type of solar cells. Generally, increase in thickness of MAPbI3 perovskite up to around 700 nm results into increase in the power conversion efficiency (PCE) of the solar cells. On the other hand, TiO2 and ZnO layers thicker than 90 nm results into decrease in the efficiency of the devices. Furthermore, the increase in interface trap density is found to reduce the efficiency of the devices. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:19.380683-05:
      DOI: 10.1002/pssc.201510078
       
  • Design of GaN‐based surface plasmon LEDs to enhance the modulation
           bandwidth and light output
    • Authors: Lei Liu; Lixia Zhao, Shichao Zhu, Zhiguo Yu, Pingbo An, Chao Yang, Chunhui Wu, Jinmin Li
      Abstract: Gallium nitride based light emitting diodes have shown their advantages in the application of visible light communication (VLC) besides general illumination. However, the modulation bandwidth of current commercial GaN based LEDs still cannot meet daily application of VLC. It has been reported that the modulation bandwidth can be enhanced by the surface plasmon due to the coupling between the surface plasmon and the active region of LEDs. However, the light output may be decreased. In this study, we designed a GaN‐based surface plasmon LEDs using lateral coupling to both increase the light output and the modulation bandwidth. The finite difference time domain method was utilized to investigate the modulation bandwidth of the GaN‐based surface plasmon LEDs as well as the light output. Simulation results show that the modulation bandwidth was estimated to be ∼2.3 GHz with 2.5 times enhancement of the light output compared with conventional LED structure. This design of surface plasmon LEDs will be useful for applications in high frequency visible light communication. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:18.490358-05:
      DOI: 10.1002/pssc.201510287
       
  • Structural and optical characterization of hybrid ZnO/polymer
           core‐shell nanowires fabricated by oxidative chemical vapour
           deposition
    • Abstract: Polycrystalline (pc) n‐doped ZnO layers and n‐doped ZnO nanowires are coated with the p‐doped organic poly‐mers polypyrrole and poly(3,4‐ethylenedioxythiophene) (PEDOT) by oxidative chemical vapour deposition. The structural characterization of the polypyrrole‐coated pc‐ZnO layer shows that the thickness and homogeneity of the polymer shell depends on the amount of the oxidizing agent FeCl3. Electrical measurements of the formed pn‐junction prepared with 0.1 g and 0.3 g FeCl3, show ideality factors of η = 1.7 and η = 4, representing the quality of the formed diode (ideal case η = 1), which is decreasing with increasing amount of oxidizing agent. Structural studies of the hybrid core‐shell nanowires reveal that a thin and homogeneous coating of the nanowires is achieved by using 0.1 g FeCl3. Energy dispersive X‐ray measurements confirm that chlorine is incorporated into the polymer shell. Optical characterization of the hybrid structures via photoluminescence measurements show a broadening of the exciton lines of the ZnO nanowires after polymer coating (especially for PEDOT) which is attributed to etching processes of the wire surface occurring during the application of FeCl3, whereas, the general optical properties of ZnO are not affected. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:17.658789-05:
      DOI: 10.1002/pssc.201510250
       
  • Green laser diodes with low operation voltage obtained by suppressing
           carbon impurity in AlGaN: Mg cladding layer
    • Authors: Aiqin Tian; Jianping Liu, Liqun Zhang, Masao Ikeda, Shuming Zhang, Deyao Li, Xiaowang Fan, Kun Zhou, Pengyan Wen, Feng Zhang, Hui Yang
      Abstract: Electrical properties of Al0.07Ga0.93N: Mg samples with different carbon impurity concentrations were investigated by Hall measurements. By reducing carbon impurity concentration from 2×1018 cm‐3 to 5×1016 cm‐3, the resistivity of p‐Al0.07Ga0.93N decreases from 7.4 Ω·cm to 2.2 Ω·cm. By applying the growth conditions of low‐temperature AlGaN: Mg with low carbon incorporation to cladding layer of green LD structure, we have obtained green LDs with series resistance as low as 2.4 Ω and operation voltage of 4.9 V at 4 kA/cm2. The green LDs lased at 508 nm with a threshold current density of 8.5 kA/cm2and a slope efficiency of 0.22 W/A. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:16.35217-05:0
      DOI: 10.1002/pssc.201510186
       
  • Quasi‐one‐dimensional gold grating with Si3N4 cap layer as
           optical coupler for AlGaN/GaN quantum well infrared photodetector
    • Authors: Shuai Wang; Feng Wu, Jun Zhang, Hanling Long, Zheng Gong, Jiangnan Dai, Changqing Chen
      Abstract: Quasi‐one‐dimensional gold grating with Si3N4 cap layer has been studied to enhance the optical coupling of AlGaN/GaN quantum well infrared photodetector (QWIP) by finite element method (FEM). The averaged Ez 2 across the whole quantum well region reaches 1.49 (V/m)2 when the electric field intensity ( E0 2) of normal incidence is 1 (V/m)2 at 4.6 μm, showing 1.9 times increase compared with that obtained via bare gold grating. The results show that Si3N4 cap layer plays an indispensable role in inducing the electric field component Ez perpendicular to multi‐quantum wells (MQWs) via not only decreasing the Fresnel reflection but also exciting stronger plasmonic resonance on the upper surface of the quasi‐one‐dimensional gold grating. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:15.630484-05:
      DOI: 10.1002/pssc.201510179
       
  • Collinear and degenerate polariton pair emission via
           biexciton‐resonant hyper‐parametric scattering
    • Authors: Hayate Shimizu; Goro Oohata, Yasuo Yamamoto, Kohji Mizoguchi
      Abstract: We report on the efficient generation of the collinear and degenerate polariton pair via biexciton‐resonant hyper‐parametric scattering (RHPS) in a CuCl single crystal using the non‐collinear and two‐color excitation method. By using this excitation method, a strong emission peak is observed at one‐half of the biexciton energy (Ebx/2). The strong emission obtained at Ebx/2 originates from the collinear and degenerate scattered polariton pair generated through the RHPS process. Furthermore, it is found that the energies of the scattered polaritons are split and deviated from Ebx/2, when the energies of the two excitation pulses are changed. We discuss the variation of the scattered polariton energies with changing the energies of the two excitation pulses on the basis of the phase matching condition for the RHPS process. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:14.756115-05:
      DOI: 10.1002/pssc.201510150
       
  • Phototransport in colloidal nanoplatelets array
    • Abstract: Colloidal nanocrystals are promising materials for achieving low cost optoelectronic devices. In this paper, we focus on the transport and photo transport properties of 2D nanoplatelet thin films and their use for photodetection. We present evidence that improved performances relies on good trap passivation as well as overcoming the inherent large exciton binding energy of the 2D NPL. This can be achieved using a phototransistor configuration with transport at the single particle scale (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-22T02:40:13.932175-05:
      DOI: 10.1002/pssc.201510165
       
  • Luminescent activity of two‐level molecule with population inversion
    • Authors: Ryosuke Hata; Hiroshi Ajiki, Nobuhiko Yokoshi, Hajime Ishihara
      Abstract: A novel technique for up‐converted luminescence generation from a two‐level molecule via population inversion is studied using the quantum toy model; this model is used to represent a coupled‐molecule and metallic nano‐antenna system sustaining a localized surface plasmon polariton (LSPP). The metallic nano‐antenna is assumed to have anharmonicity, reflecting experimentally observed results. The system is driven by a strong, offresonant, and Gaussian pulse laser so that the LSPP exhibits a Mollow triplet spectrum. When the two‐level molecular resonance is tuned to the upper Mollow triplet sideband, the molecular‐level population is inverted. We discuss the population dynamics, the Purcell effect, and the up‐converted luminescence activity of the two‐level molecule. These results indicate the potential applications of the present system in novel coherent light sources. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:18.120388-05:
      DOI: 10.1002/pssc.201510157
       
  • InN/GaN short‐period superlattices as ordered InGaN ternary alloys
    • Authors: Kazuhide Kusakabe; Daichi Imai, Ke Wang, Akihiko Yoshikawa
      Abstract: Coherent (InN)1/(GaN)n short‐period superlattices (SPSs) were successfully grown through dynamic atomic layer epitaxy (D‐ALEp) mode by RF‐plasma molecular beam epitaxy (MBE), where GaN layer thicknesses n were thinned down to 4 monolayer (ML). After this achievement, we demonstrated quasi‐ternary InGaN behavior in their photoluminescence (PL) spectra for the first time. It was found interestingly that GaN layer thickness of n = 4 ML was the criterion both for structural control and continuum‐band formation. Although highly lattice‐mismatched InN/GaN interfaces easily introduce relaxation in (InN)1/(GaN)4 SPSs during growth depending on the dynamic surface stoichiometry condition, this problem was overcome by precise control/removal of fluid‐like residual In/Ga metals on the growth front with in‐situ monitoring method. The (InN)1/(GaN)n SPSs with n ≥ 7 ML showed a constant PL peak energy around 3.2 eV at 12 K, reflecting discrete electron/hole wavefunctions. On the other hand, the (InN)1/(GaN)4 SPSs indicated the red‐shifted PL peak at 2.93 eV at 12 K, which was attributed to the continuum‐band state with increasing in the overlap of electrons/hole wavefunctions. This result is concluded that the (InN)1/(GaN)4 SPSs can be considered as ordered InGaN alloys. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:17.322577-05:
      DOI: 10.1002/pssc.201510306
       
  • Growth and optical properties of gallium nitride film on glass substrates
    • Authors: Pingbo An; Lixia Zhao, Shuo Zhang, Lei Liu, Ruifei Duan, Xuecheng Wei, Hongxi Lu, Junxi Wang, Jinmin Li
      Abstract: In this study, gallium nitride (GaN) films were grown on the quartz glass substrates using metal organic chemical vapor deposition with AlN buffer layer. The AlN layer was deposited using rf‐magnetron sputtering. Although the direct nucleation of GaN on quartz glass substrate is difficult, with AlN as the nucleation layer, a large‐area polycrystalline GaN film can be obtained. The structural and optical properties were investigated. The results show that the GaN film has a preferential orientation along (0002). There are mainly three emission regions in the photoluminescence spectra, including the band‐edge, green (2.45‐2.55eV) and yellow (2.0‐2.35 eV) emission regions. The origin and temperature dependence of the peak position, full‐width of half‐magnitude and intensity were also discussed. The findings may help to understand the growth and improve the properties of GaN film grown on amorphous glass substrates. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:16.332933-05:
      DOI: 10.1002/pssc.201510207
       
  • Deep ultraviolet lasing from AlGaN multiple‐quantum‐well
           structures
    • Authors: Jianchang Yan; Yingdong Tian, Xiang Chen, Yun Zhang, Junxi Wang, Jinmin Li
      Abstract: We report our research work on AlGaN/Al(Ga)N multiple‐quantum‐well (MQW) DUV laser structures. Two types of MQW structures, that is, AlxGa1‐xN/AlyGa1‐yN MQW (Sample A) and AlzGa1‐zN/AlN MQW (Sample B), were grown on sapphire substrates by Metal‐organic chemical vapour deposition. Optically pumped lasing at room temperature has been achieved from both structures. For Sample A, the main lasing emission wavelength is 288 nm along with some parasitic longer wavelength peaks. Numerical simulation results indicate that the optical confinement factor in Sample A is very low, less than 0.5%. This resulted in the high lasing threshold and short lasing lifetime of Sample A. The optical confinement factor of Sample B is greatly increased to more than 10%. This effectively improved the lasing performance of Sample B. Its lasing threshold is estimated to be 523 kW/cm2 and the lasing spectra peaked at around 281 nm. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:15.54824-05:0
      DOI: 10.1002/pssc.201510192
       
  • Below‐gap emission bands in undoped GaN and its excitation density
           dependence
    • Authors: M. Julkarnain; T. Fukuda, N. Kamata, Y. Arakawa
      Abstract: The below‐gap emission bands of undoped GaN grown by MOCVD on sapphire substrate have been investigated by photoluminescence technique. The intensity of yellow luminescence decreases due to the saturation of deep states with increasing excitation power that reflects the contribution of deep states at actual device operating condition. The excitation induced blue‐shift of emission energy rationalizes the DAP characteristics. The integrated photoluminescence intensity of each band is analysed experimentally and theoretically by a power law model, and the reasonable agreement between experiment and model calculation justify our model consideration. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:14.755262-05:
      DOI: 10.1002/pssc.201510190
       
  • Photoluminescence from exciton‐electron inelastic scattering in a
           GaAs/AlAs multiple‐quantum‐well structure
    • Authors: Saeka Nakanishi; Yoshiaki Furukawa, Masaaki Nakayama
      Abstract: We have investigated the characteristics of photoluminescence (PL) from exciton‐electron inelastic scattering in a GaAs (5.1 nm)/AlAs (5.1 nm) multiple‐quantum‐well structure. The excitation power dependence of PL spectra was measured in a wide temperature region from 10 to 285 K. We detected a PL band which appears with a threshold‐like nature at each temperature. In a low temperature region below ∼80 K, the energy spacing between the threshold‐like appearance PL band and heavy‐hole exciton almost agrees with the exciton binding energy. This indicates that the PL band originates from well‐known exciton‐exciton inelastic scattering. In contrast, in a high temperature region above ∼90 K, the energy spacing continuously increases with an increase in temperature. The temperature dependence of the energy spacing is explained by a theoretical model for exciton‐electron inelastic scattering considering energy and momentum conservation in the scattering process. Thus, it is concluded that the mechanism of the threshold‐like appearance PL band related to exciton inelastic scattering changes with temperature. In addition, we confirmed that the exciton‐electron inelastic scattering produces an optical gain using a variable stripe length method for PL measurements. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:14.001504-05:
      DOI: 10.1002/pssc.201510126
       
  • Photoexcited d ‐electron dynamics in transition metal oxide MnO
           studied by optical pump‐THz probe measurements
    • Authors: Junichi Nishitani; Takayuki Kurihara, Akifumi Asahara, Takeshi Nagashima, Mikk Lippmaa, Tohru Suemoto
      Abstract: Optical pump‐THz probe (OPTP) measurements allow us to investigate the dynamic response of photoconductivity in materials by observing the transient change of THz transmittance after optical excitation. In this study, the THz response of d ‐electrons in various photoexcited states in MnO was investigated by pump‐energy‐tunable OPTP measurements to elucidate the photoexcited d ‐electron dynamics in a transition metal oxide. At room temperature, photoexcited d ‐electrons induced by a d ‐d transition to the lowest excited d ‐state showed the longest relaxation time. The relaxation time decreased drastically below the antiferromagnetic transition temperature of 120 K. This decrease was accompanied by the emergence of magnetic‐excitation‐assisted photoluminescence from a self‐trapped exciton (STE) state. This suggests that photoexcited d ‐electrons relax to the STE state below the transition temperature. These findings shed new light on the photoexcited d ‐electron dynamics, contrasting with the behavior of photoexcited carriers generated in the upper excited d ‐states that have been shown in a previous study to relax into trap states through carrier scattering. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-12-09T03:50:13.234256-05:
      DOI: 10.1002/pssc.201510086
       
  • AgSb(SxSe1‐x)2 thin films by rapid thermal processing of
           Sb2S3‐Ag‐Se thin films for photovoltaic applications
    • Authors: Dorian Leonardo Rodriguez Vela; Bindu Krishnan, Josue Amilcar Aguilar Martinez, Shadai Lugo Loredo, Sadasivan Shaji
      Abstract: Silver antimony sulfoselenide thin films have been investigated for photovoltaic applications. In the present work, we report preparation of AgSb(SxSe1‐x)2 by a rapid thermal processing of pre‐annealed Sb2S3/Ag/Se/Ag/Se layered structures. Sb2S3thin films were deposited by chemical bath deposition and Ag by thermal evaporation. Silver (Sb2S3/Ag) layered precursors were dipped in Na2SeSO3 solution followed by annealing and then rapid thermal processing. Also, photovoltaic structures were prepared using AgSb(SxSe1‐x)2 thin films as absorber and CdS as window material. The effects of rapid thermal processing on the structure, morphology and properties of these thin films were studied. Characterization of the absorber materials was done using X‐ray diffraction, X‐ray photoelectron spectroscopy, Atomic force microscopy, Optical absorption spectroscopy and Current‐voltage characteristics. Analysis of J ‐V characteristics of the photovoltaic structures under AM1.5 illumination before and after rapid thermal treatment showed Voc in a range of 457 to 473 mV and Jsc of 5.8 to 7.2 mA/cm2. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-26T06:10:05.395802-05:
      DOI: 10.1002/pssc.201510117
       
  • Enhancement of emission intensity of LaVO4:RE3+ luminescent solar light
           absorbers
    • Authors: V. Chornii; O. Chukova, S. G. Nedilko, S. A. Nedilko, T. Voitenko
      Abstract: The investigated La1–xRExVO4 (RE = Eu, Sm) solid solutions are characterized by intensive emission of the RE ions that is excited from the wide spectral range including UV region of intrinsic transitions in the vanadate host. We have carried out comparable analysis of characteristics of the La1–xRExVO4 compounds synthesized by three different methods: solid state reaction, co‐precipitation and sol‐gel synthesis. The investigation revealed differences in luminescence and excitation spectra of samples obtained by different methods. Spectra of the samples with lower activator concentrations have a more complicated character. They contain exceed number of lines that is caused by formation of two types of RE3+ emission centers. Spectral exhibitions of the second (“at surface”) type of centers are observed up to x = 0.05, 0.1 and 0.3 for samples synthesized by solid state, co‐precipitation and sol‐gel methods, respectively. The presence of the “at surface” type of centers leads to essential increasing of total intensity of emission. Differences in excitation spectra give us a possibility to suppose that enhancement of luminescence intensity is also due to expanded excitation range caused by “at surface” centers in UV region. Therefore, “at surface” centers satisfy better absorption of UV light. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-26T05:10:18.901541-05:
      DOI: 10.1002/pssc.201510116
       
  • Photoluminescence dynamics of formation of electron‐hole droplets in
           a GaAs/AlAs type‐II superlattice
    • Authors: Yoshiaki Furukawa; Masaaki Nakayama
      Abstract: We report photoluminescence (PL) dynamics at 10 K in a GaAs/AlAs type‐II superlattice, in which electrons (holes) are confined in the AlAs (GaAs) layer, focusing on dynamical formation of electron‐hole droplets (EHDs) from electron‐hole plasma (EHP) in a gas phase. It was found from systematic time‐resolved PL (TRPL) spectra that only a broad PL band attributed to the EHP is observed in an initial time region within ∼0.4 ns, whereas the exciton‐ and biexciton‐PL bands appear and grow with time after ∼0.7 ns. In the time region after ∼14 ns, the line shape of the broad PL band hardly depends on time; namely photogenerated carriers are in quasi‐thermal equilibrium. The stability energy of the EHD was estimated to be ∼3.1 meV relative to the biexciton energy from the line‐shape analysis of the TRPL spectrum at 30 ns. Consequently, the above temporal changes of the line shape of the broad PL band demonstrate the dynamical transition from the EHP to the EHD during the PL decay process. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-26T05:10:17.390591-05:
      DOI: 10.1002/pssc.201510121
       
  • Gas phase silanization for silicon nanowire sensors and other
           lab‐on‐a‐chip systems
    • Authors: Annina M. Steinbach; Tanja Sandner, Boris Mizaikoff, Steffen Strehle
      Abstract: Designing a microfabrication process for lab‐on‐a‐chip systems can at times be challenging, and the need to integrate a chemical surface modification reaction into this process can limit the options. Therefore, a robust set‐up and protocol for the gas phase modification has been developed that can be variably integrated into microfabrication processes. The main improvement compared to similar methods is, besides easy and versatile sample handling, the integration of a continuous argon flow percolating through the liquid organosilane, and impinging directly the surface tobe modified. This measure reduces the argon consumption drastically compared to current reaction schemes, while keeping short reaction periods. Silicon substrates were modified using 3‐mercaptopropyltrimethoxysilane (MPTMS) and 3‐aminopropyltrimethoxysilane (APTMS), thoroughly studied for different reaction stages, and compared to surfaces modified via a common solvent‐based procedure from isopropanolic solution. Water contact angle measurements, infrared spectroscopy, X‐ray photoelectron spectroscopy, and atomic force microscopy verified the successful deposition of the alkylsilane. Additionally, silicon nanowires were assembled, exemplary for a lab‐on‐a‐chip system, in a liquid gate field‐effect‐transistor configuration, and electrically characterized. The devices showed the expected response to applied liquid gate potentials before and after the modification and exhibited characteristic changes in the transconductance curve. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-19T06:50:22.672789-05:
      DOI: 10.1002/pssc.201510211
       
  • The zero phonon line revisited
    • Authors: Mark C. A. York
      Abstract: We treat the exciton–thermal acoustic phonon interaction as a coupling to a (not necessarily classical) stochastic background, in turn applying a Luttinger–Ward style of resummation to self–energy diagrams and leading to a non–perturbative resolution of the exciton spectral density. Such an approach is useful in settings where higher order corrections are not small, e.g. finite temperature and certain processes involving optical phonons. Our main observations lend a promising outlook for applications with quantum wires, quantum dots and localized states as well as a similar non–perturbative description of optical phonon relaxation/emission processes. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-19T06:50:21.492144-05:
      DOI: 10.1002/pssc.201510073
       
  • Evidence for formation of self‐trapped excitons in a
           β‐Ga2O3 single crystal
    • Authors: Suguru Yamaoka; Masaaki Nakayama
      Abstract: We have investigated photoluminescence (PL) and absorption properties of a β‐Ga2O3single crystal from the viewpoint of the stability of self‐trapped excitons (STEs). A broad PL band with a large Stokes shift, which is conventionally assigned to the STE, was observed. To reveal the stability of the STE, we precisely measured the temperature dependence of the Urbach tails in absorption spectra. It was confirmed that the Urbach tails at all temperatures converge into a specific point, which verifies the validity of the treatment of the Urbach tail. We analysed the temperature dependence of the exponential slope, the so‐called steepness constant, of the Urbach tail and evaluated the exciton‐phonon coupling constant g, which defines the stability of the STE, to be g = 5.4. Based on a previously reported theory for exciton‐phonon interactions, g > 1 generally results in that the STE is a stable state relative to a free exciton. Consequently, the above large g factor demonstrates that the STE formation is stable in β‐Ga2O3. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-12T03:52:17.799699-05:
      DOI: 10.1002/pssc.201510124
       
  • Tailoring the ultrafast control of quantum dot excitons using optical
           pulse shaping
    • Authors: Reuble Mathew; Kimberley C. Hall
      Abstract: Femtosecond pulse shaping provides a means to tailor the interaction of light with matter, enabling the optimization of optical control processes and the achievement of a target final quantum state of the matter system. While this approach has found widespread application in the control of atomic and molecular systems, its use for solid state quantum systems remains in its infancy. This review covers our application of this approach to the manipulation of the quantum states of excitons in semiconductor quantum dots (QDs). The achievement of simultaneous π, 2π rotations on excitons in two different QDs using a single engineered infrared pulse illustrates the flexibility of the pulse shaping approach for solid state quantum systems. This versatility is further explored through simulations that show the feasibility of arbitrary SU(2) control of several quantum dots. Shaping of femtosecond infrared control pulses enables the demonstration of adiabatic rapid passage in a single QD on a subpicosecond time scale, representing a substantial speedup and an important step towards the realization of dynamical decoupling. The dependence of the exciton inversion efficiency on the sign of pulse chirp confirms the role of (and ability to control) phonon‐related dephasing. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-09T05:10:07.86105-05:0
      DOI: 10.1002/pssc.201510152
       
  • Spray pyrolysed thin films of copper antimony sulfide as photovoltaic
           absorber
    • Authors: Jose Agustin Ramos Aquino; Dorian Leonardo Rodriguez Vela, Sadasivan Shaji, David Avellaneda Avellaneda, Bindu Krishnan
      Abstract: Copper antimony sulfide (CuSbS2) thin films have been gained interest recently as an emerging light absorbing material for photovoltaic applications. In this work we report synthesis and characterization of spray pyrolised CuSbS2 thin films. The precursor solution consisted of SbCl3, CuCl2 and NH2CSNH2 dissolved ethanol. The substrate temperature was kept at 200 °C. Samples were prepared at different molar ratios of Cu:Sb:S. These thin films were characterized using X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, UV‐visible spectroscopy, photocurrent and Hall effect measurements. P‐type CuSbS2 thin films of orthorhombic structure were formed and the films showed photocurrent response. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-11-09T04:50:21.695263-05:
      DOI: 10.1002/pssc.201510102
       
  • Comparative study of SnS recrystallization in molten CdI2, SnCl2and KI
    • Abstract: In the present study, the recrystallization of polycrystalline SnS in different molten salts CdI2, SnCl2 and KI as flux materials are presented. The recrystallization and growth of polycrystalline material in molten salts produces unique SnS monograin powders usable in monograin layer solar cells. XRD and Raman analysis revealed that single phase SnS powder can be obtained in KI at 740 °C and in SnCl2 at 500 °C. Long time heating of SnS in molten CdI2 was accompanied by chemical interaction between SnS and CdI2 that resulted in a mixture of CdS and Sn2S3 crystals. SEM images showed that morphology of crystals can be controlled by the nature of the flux materials: needle‐like Sn2S3 together with round edged crystals of CdS in CdI2, flat crystals of SnS with smooth surfaces in SnCl2 and well‐formed SnS crystals with rounded edges in KI had been formed. The temperatures of phase transitions and/or the interactions of SnS and flux materials were determined by differential thermal analysis. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:16.694713-05:
      DOI: 10.1002/pssc.201510082
       
  • Tin sulfide films by spray pyrolysis technique using L‐cysteine as a
           novel sulfur source
    • Authors: Svetlana Polivtseva; Ilona Oja Acik, Atanas Katerski, Arvo Mere, Valdek Mikli, Malle Krunks
      Abstract: Tin sulfide films were deposited by spray pyrolysis method using aqueous solutions containing tin chloride (SnCl2) and L‐cysteine (HO2CCH(NH2)CH2SH) as a novel source of sulfur instead of commonly used thiourea. L‐cysteine prevents SnCl2 from hydrolysis due to a complex formation as confirmed by Fourier Transformed Infrared Spectroscopy studies. The solution that contained SnCl2 (Sn) and L‐cysteine (S) at molar ratios of Sn:S=1:1, 1:2 and 1:4 was sprayed onto glass substrates at varied temperatures between 200 °C and 370 °C. Films were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and UV‐Vis spectroscopy. Accord‐ ing to XRD, spray of the 1:1 solution results in films that are composed of SnS as a main crystalline phase. An unidentified crystalline phase was present independent of the growth temperature. Single phase SnS films with bandgap value of 1.7 eV could be grown using the 1:2 solution at deposition temperature of 370 °C. Films grown from 1:4 solutions are amorphous using deposition temperatures below 370 °C, and composed of a mixture of SnS and Sn2S3 phases when grown at 370 °C. EDX study shows that SnS films contain high amount of carbon and oxygen containing residues independent of the deposition temperature and precursors' molar ratio in the spray solution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:14.910578-05:
      DOI: 10.1002/pssc.201510098
       
  • Synthesis of MAPbBr3‐iYi (Y=I, Cl and i=0, 1, 2, 3) thin film
           perovskites
    • Abstract: Methylammonium lead halide perovskites with different halides (iodide, bromide and chloride) have been synthetized from methylamine, lead nitrate and the corresponding hydroX acid (X = I, Br, Cl) precursors. Subsequently MAPbBr3‐iYi (Y = I, Cl; i=0, 1, 2, 3) perovskites were deposited as thin films onto FTO substrates by spin coating or dipping. Thin film perovskites were then characterized by X‐Ray Diffraction, elemental analysis and optical spectrometry. Crystallites' sizes are between 100‐600 nm depending on the synthesis temperature. All synthetized MAPbX3‐iYi perovskites crystallized in the same cubic phase irrespective of the X and Y components and a unique phase is observed. Elemental analysis shows that in all cases the atomic components meet the expected stoichiometric formulae. The bandgap of thin film MAPbX3‐iYi perovskites were inferred from transmittance and reflectance spectral measurements. It is found that the onset of the absorption edge for thin film MAPbX3 perovskites is about 1.66, 2.55 and 3.37 eV for X= I, Br, Cl, respectively and it reaches intermediate values for mixed MAPbX3‐iYi perovskites. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:12.97447-05:0
      DOI: 10.1002/pssc.201510107
       
  • Energy transfer between Tl+‐type impurities in NaCl crystals
    • Authors: Akitoshi Iguchi; Taketoshi Kawai, Kohji Mizoguchi
      Abstract: We have investigated the energy transfer from Tl+ centers to In+ centers at RT in co‐doped NaCl:Tl+, In+ crystals by measuring absorption, photo‐excitation, luminescence and time‐resolved spectra. The A' luminescence band of the In+ centers is observed under excitation at the absorption band of the Tl+ centers. The A' luminescence band of the Tl+ centers measured at a forward configuration exhibits a dent structure at 4.2 eV corresponding to the A absorption band of the In+ centers. The facts indicate the existence of the energy transfer from the Tl+ to In+ centers through the emission‐reabsorption mechanism. On the other hand, the A' luminescence of the Tl+ centers shows a non‐exponential decay profile. As the concentration of the In+ centers increases, the non‐exponential decay profile becomes faster. The resonance energy transfer giving the non‐exponential decay profile is discussed on the basis of the dipole‐dipole interaction. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:12.032028-05:
      DOI: 10.1002/pssc.201510149
       
  • Study of intersystem crossing mechanism in organic materials
    • Authors: David Ompong; Jai Singh
      Abstract: Intersystem crossing rate from singlet excited state to triplet excited state of an organic molecule has been derived using exciton‐spin‐orbit‐molecular vibration interaction as a perturbation operator. Incorporation of heavy metal atom enhances the spin‐orbit interaction and hence the intersystem crossing rate because it depends on the square of the heaviest atomic number. We found that in the presence of heavy atom the singlet‐triplet energy difference still plays an influential role in the intersystem crossing process. The derived exciton‐spin‐orbit‐molecular vibration interaction operator flips the spin of the singlet exciton to triplet exciton after photoexcitaion from the singlet ground state with the assistance of molecular vibrational energy. From this operator an expression for the intersystem crossing rate is derived and calculated in some organic solids. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:10.966785-05:
      DOI: 10.1002/pssc.201510128
       
  • Cu2SnS3 based solar cell with 3% efficiency
    • Authors: R. Chierchia; F. Pigna, M. Valentini, C. Malerba, E. Salza, P. Mangiapane, T. Polichetti, A. Mittiga
      Abstract: Cu2SnS3 is an earth abundant material suitable for photovoltaic applications. Unfortunately, the material still suffers of a low diffusion length of the carriers due to the presence of spurious phases, voids, defects and small grain size. In order to improve the quality of our samples, the influence of the deposition parameters on its structural properties has been studied. The solar cell obtained with the optimized Cu2SnS3 has shown an external quantum yield larger than 80% around 500 nm a conversion efficiency in the order of 3%, a Jsc of 26 mA and a Voc of 240 mV, one of the world best result obtained with a Cu2SnS3 based solar cell. Furthermore the external quantum yield at wavelength larger than 1200 nm is still around 30% making this material interesting for IR detectors also. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-29T03:10:10.116056-05:
      DOI: 10.1002/pssc.201510115
       
  • Comparative contributions of singlet and triplet excitons in the
           performance of organic devices
    • Authors: Jai Singh; Monishka R. Narayan, David Ompong
      Abstract: The properties of singlet and triplet excitons are compared in organic materials for applications in optoelectronic organic solar cells (OSCs) and organic light emitting devices (OLEDs). It is found that by managing the organic material designs both singlet and triplet excitons can be beneficially used in OSCs and OLEDs equally well. A model of dissociation of excitons excited in the acceptor material of the bulk heterojunction organic solar cells is presented. It is shown that the dissociation of acceptor excitons also can contribute to the photovoltaic performance of OSCs. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-26T06:10:31.014892-05:
      DOI: 10.1002/pssc.201510127
       
  • Polariton dispersion relations under condensation in a CuBr microcavity
    • Authors: Masaaki Nakayama; Katsuya Murakami, DaeGwi Kim
      Abstract: We have investigated the exciton‐polariton condensation in a CuBr microcavity with HfO2/SiO2 distributed Bragg reflectors, focusing on condensation effects on polariton dispersion relations. The polariton distribution as a function of in‐plane wave vector k// under illumination was measured with angle‐resolved photoluminescence (PL) spectroscopy. In addition, we characterized the intrinsic polariton dispersion relations as reference data from analysis of the results obtained using angle‐resolved reflectance spectroscopy. It was found that the polariton condensation causes a large blueshift of the lower polariton branch (LPB) and a flat dispersion relation around the ground state at k//=0. The renormalized dispersion relation of the LPB under the polariton condensation was quantitatively analysed using a theory for a diffusive Goldstone mode peculiar to nonequilibrium condensation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-26T06:10:25.553577-05:
      DOI: 10.1002/pssc.201510076
       
  • Modeling of transient photocurrent in X‐ray detectors: application
           to a‐Se
    • Authors: Sinchita Siddiquee; M. Z. Kabir
      Abstract: A mathematical model for transient photocurrent in X‐ray imaging detectors has been developed by considering charge carrier trapping under exponentially distributed carrier generation across the photoconductor. The model for the transient and steady‐state carrier distributions and hence the photocurrent has been developed by solving the carrier continuity equation for both holes and electrons. The model is applied to amorphous selenium (a‐Se) detectors for both chest radiography and mammography. We analyze the transient rise and decay of the photocurrent profile as a function of time. The quick rise and decay parts, and then the slow rise and decay parts of the photocurrent profile are due to the hole and electron transports, respectively. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
      PubDate: 2015-10-12T08:41:30.41137-05:0
      DOI: 10.1002/pssc.201510129
       
  • 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
       
  • 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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