AlN原料的钨网炉高温提纯

商品氮化铝粉料中含有高浓度的氧、碳及金属杂质,需经过高温提纯处理后才能用于物理气相法氮化铝晶体生长。与感应加热相比,钨网电阻加热可有效避免碳、氧等的二次沾污,势必具有良好的提纯效果。本文采用钨网炉对AlN原料进行高温烧结提纯处理,通过X射线能谱仪(EDS)、气体分析技术(IGA)和辉光放电质谱仪(GDMS)对烧结处理后AlN的杂质含量进行了测试分析,结果表明经钨网炉高温烧结处理后,AlN原料中杂质含量明显降低,其中的氧、碳去除效果显著。还进一步分析了杂质挥发、原料损耗随温度、时间变化的规律。     

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。     

Structural and magnetic properties of Yb-implanted GaN

N-type,p-type and unintentionally-doped GaN were implanted with Yb ions by double energy ion implantation and the samples were annealed at 900℃.The structural and magnetic properties of the samples have been studied by high-resolution X-ray diffraction(HRXRD),Raman scattering and with a superconducting quantum interference device(SQUID).No second phase has been observed and implantation induced defects can not be completely removed by rapid thermal annealing.The annealed samples show magnetic anisotropy and clear ferromagnetic behavior at room temperature.P-,u- and n-GaN:Yb samples show an effective magnetic moment of 1.60,1.24 and 0.59μ_B/Yb,respectively.