共查询到20条相似文献,搜索用时 15 毫秒
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K. D. Glinchuk A. V. Prokhorovich F. M. Vorobkalo 《Crystal Research and Technology》1998,33(5):833-839
An analysis is made of the effect of the copper diffusion into semi-insulating undoped GaAs crystals on the intensity of the intrinsic luminescence. It is shown that the copper diffusion into semi-insulating undoped GaAs crystals could lead both to an increase and to a decrease in the intrinsic luminescence intensity. Analytical expressions connecting the value and the sign of the effect observed with the recombination parameters of crystals pointed and also with the intensity of luminescence excitation are obtained. 相似文献
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Atomic absorption spectroscopy (AAS) is used to determine the Ge concentration in Ga1–xInxAs and GaAs. The orientation dependence of Ge incorporation in (111)A-and (111)B oriented samples has been studied. The distribution coefficients for both the orientations were determined to be kGe(111)A = 2.6 · 10−2 and kGe(111B = 1.4 · 10−2 for Ga1–xInxAs with 0 ≦ x ≦ 0.13. The differences between the two orientations are explained with the aid of the band bending model. Doping gradients in thick epitaxial layers and along crystal length of polycristalline TGS-grown GaAs ingots have been investigated too. In Ga1–xInxAs layers any Ge concentration gradient couldn't be observed, but in TGS compact crystals Ge concentration increases with crystal length because the melt composition changes significantly during solidification. The results are compared with those of electrical measurements. 相似文献
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本文首先简要介绍了晶体的重要性和过去几十年来中国晶体材料研究取得的代表性成果.正文主要以我们课题组开展的工作为例,介绍了激光晶体、非线性光学晶体、磁光晶体、声光晶体、半导体晶体、有机晶体、有机-无机复合晶体、二维晶体、单晶光纤、药物结晶、微纳米晶体等方面的研究进展.这些研究实例的维度已覆盖体块-二维-一维-零维,晶体材料已在国防、经济建设、人类健康和科学技术发展的许多领域,发挥了重要作用并仍将是关键材料. 相似文献
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The silicon doped GaAs single crystals were grown by means of a horizontal Bridgman method. The relation between the free carrier concentration and silicon concentration determined by chemical analysis was examinated. 相似文献
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Crystallography Reports - The influence of a dc magnetic field on the motion of growth dislocations with a density of (0.7–7.0) × 104 cm–2 and the electron density in the range of... 相似文献
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V. A. Antonov P. A. Arsenev B. A. Baranov N. D. Barinova E. F. Kustov I. G. Linde 《Crystal Research and Technology》1974,9(12):1403-1410
An information is given on the kinetics of developing ionization defects by γ-radiation, as well as on the destroying of these defects as a result of thermal treatment in oxidizing atmosphere at different temperatures. The presence of several types of ionization defects developing by γ-radiation is found out. Values of diffusion factor for each type of defects are given. 相似文献
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用电阻加热提拉法生长了一系列较大尺寸,组分离子均匀性较好的铌酸钾锂晶体.利用X射线荧光光谱法测量了不同配比的熔体中生长出的晶体组成,用同步辐射X射线测量了晶体结构,结果表明随晶体组成变化,晶体的晶格常数发生了变化.根据晶体组分离子浓度与折射率的关系研究了晶体折射率变化情况,结果表明用本方法生长的大尺寸KLN晶体,寻常折射率no在测量误差范围内没有变化,非寻常折射率ne的变化率在820nm仅为1.22×10-4/mm,在410nm仅为1.93×10-4/mm.晶体的干涉条纹证明了晶体有良好的光学均匀性.结合晶体生长实验,探讨了改进晶体组分离子浓度分布均匀性的方法,结果表明采用籽晶和坩锅向相同方向旋转可以改善晶体生长界面处组分离子浓度的波动,提高晶体组分离子均匀性.晶体的缺陷研究表明晶体结构完整性较好,位错形状与晶体结构相一致,密度为7.5×104,[001]轴是晶体的极化轴.晶体对890~960nm波长范围的cw-Ti:sapphire激光倍频结果表明晶体有良好的倍频性能. 相似文献
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铌酸锂晶体的缺陷及其控制 总被引:1,自引:0,他引:1
针对铌酸锂晶体中的缺陷研究,本文总结了国内外学者提出的不同晶体缺陷模型及各自的特点,并介绍了我们提出的铌位依赖、锂位敏感模型.在分析晶体缺陷研究的基础上提出了对铌酸锂晶体进行缺陷控制的意义及理论依据,指出缺陷控制的主要任务是保护锂格位.本文还简要概括了铌酸锂晶体缺陷控制的主要手段,并建议从反映铌酸锂晶体性能的角度来研究缺陷结构. 相似文献
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通过物理气相传输(PVT)法在石墨系统中制备了绿色、无色和琥珀色氮化铝(AlN)单晶,在金属系统中制备了琥珀色AlN单晶.晶体中杂质含量测试结果表明石墨系统中琥珀色的AlN晶体比绿色和无色AlN晶体C、Si杂质含量低1~2个数量级,金属系统中琥珀色AlN晶体杂质含量最低,C、Si、O元素含量均在1018 cm-3级别.AlN晶体的吸收图谱和光致发光图谱的分析结果表明,AlN晶体存在着位于4.7 eV、3.5 eV、2.8 eV、1.85 eV的4个吸收峰,其中4.7 eV和3.5 eV的吸收峰导致了AlN吸收截止边的红移,该吸收峰分别源于碳占氮位(CN)的点缺陷和VAl与O杂质的复合缺陷,2.80 eV的吸收峰导致了AlN晶体的琥珀色,该吸收峰是C元素和O元素共同导致的,1.85 eV的吸收峰导致了AlN晶体的绿色,该吸收峰是Si元素和C元素导致的. 相似文献
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Crystalline defects in Sn-doped LEC indium phosphide have been revealed by chemical etching and analyzed by TEM. Grown-in dislocations, various kinds of defect clusters and colonies of microdefects were found. The symmetrical defect clusters are shown to equate mostly with larger dislocation loops exhibiting shear components and/or other dislocation arrangements generated by a stress source which is positioned in the centre of the dislocation cluster. Those centres are often formed by a plate-like agglomeration composited of tiny inclusions and very small faulted dislocation loops. Such planarly arranged accumulations of microdefects lie on {111} planes. The direct vicinity of single threading grown-in dislocations is always enriched with tiny perfect dislocation loops and precipitates. Additionally, very large isolated interstitial-type perfect dislocation loops with b = a0/2 〈110〉 have been found by TEM experiments. Mostly, the {110} habit plane of such loops is decorated with an high number of small dislocation loops and precipitates as a consequence of dislocation climb. 相似文献
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The nature of the main electron trap, EL2, in undoped semiinsulating GaAs crystals have been studied both qualitatively and quantitatively. It has been shown that point defects which, most probably, are responsible for the EL2 level are antisite AsGa defects or (Asi VGs) complexes which are indistinguishable from the thermodynamic standpoint. The enthalpy and entropy of AsGa formation according to the reaction AsAs + VGa ⇄ AsGa + VAs are equal to 0.5 eV and −7k, respectively. 相似文献
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Wafers of commercially available semi-insulating (SI) Czochralski-grown GaAs crystals have been annealed at temperatures near the melting point (> 1100 °C) both for relatively short and long time and then rapidly quenched into cold water. Heat-treated crystals have been investigated by X-ray transmission diffraction topography. Cellular structure pattern of the as-grown sample is replaced by images of precipitates spread out over whole sample. This suggests that the excess arsenic condenses as As precipitates with nucleation sites not correlated with cell walls. 相似文献
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H. Neumann P. A. Jones H. Sobotta W. Hrig R. D. Tomlinson M. V. Yakushev 《Crystal Research and Technology》1996,31(1):63-74
Optical absorption spectra in the photon energy range from 0.03 to 1.1 eV and photoreflectance spectra in the range of the fundamental edge are measured on p-type CuInSe2 single crystals. Besides a dominant contribution to the absorption coefficient due to intervalence band transitions below about 0.75 eV the spectra revealed five additional structures that can be ascribed to defect induced optical transitions with characteristic energies between 0.48 and 0.72 eV. Based on a comparison of the near-edge optical absorption and photoreflectance spectra a shallow defect (donor or acceptor) with an ionisation energy of about 46 meV was identified. 相似文献
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