Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B₂O₃ encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters.     

硫化铵钝化锑化镓表面的化学与电学性质研究

本文利用X射线光电子能谱（XPS）,飞行时间二次离子质谱（TOF-SIMS）和电流-电压特性（I-V）对不同硫化铵溶液（(NH4)2S）钝化后的锑化镓（GaSb）表面化学性质进行了研究。通过对比,发现中性(NH4)2S S溶液对GaSb表面的钝化能力要优于纯(NH4)2S溶液和碱性(NH4)2S S溶液。碱性(NH4)2S S溶液在有效去除GaSb表面氧化物的同时形成硫化物产物以改善器件性能。TOF-SIMS测试结果从另一方面证实纯(NH4)2S溶液钝化也会形成硫化物产物,但该产物在纯(NH4)2S溶液中是可溶的,以至于很难稳定地存在。3D光学轮廓仪测试结果显示中性(NH4)2S S溶液钝化的GaSb表面具有最低的粗糙度。I-V测试结果表明中性(NH4)2S S溶液钝化能显著提高GaSb基肖特基二极管的电学性能。综上所述,中性(NH4)2S S溶液的钝化效果在改进GaSb表面性质方面具有最优的结果。     

液晶显示材料标准化发展建议

液晶显示是半导体显示技术的代表，是当前及未来一段时间内的主流显示技术。随着5G、AR/VR等新市场的兴起，显示技术作为信息技术的载体还将有更广阔的发展空间，同时对显示技术在色彩表现、响应速度、尺寸形状、能耗寿命等方面的要求也越来越高。显示技术的发展依赖于材料体系的创新，液晶显示材料呈体系化创新是显示技术创新发展的重要驱动力。标准化可以规范市场行为，推动建立最佳秩序，是促进科技成果转化为生产力的重要桥梁，也是催动贸易发展的纽带。在液晶显示材料创新成果固化、质量稳定性提升、规范市场健康发展等方面，标准化发挥了重要作用。本文从系统梳理液晶显示材料产业体系和标准现状出发，科学规划了液晶显示材料标准体系，并结合我国液晶显示标准化发展的问题和趋势，给出了标准体系重点建设的思路和建议。     

Anomalous luminescence efficiency enhancement of short-term aged GaN-based blue light-emitting diodes

The origin of anomalous luminescence efficiency enhancement of short-term aged GaN-based blue light-emitting diodes was studied. We found that the intensity of the electroluminescence and photoluminescence spectra were both increased in the very beginning period of aging. With the help of a rate-equation model, we concluded that this kind of luminescence efficiency enhancement is a joint effect of the defect reduction in active layers and the changes out of active layers, for example the Mg acceptor annealing.