摘要
ＣｄＴｅ／ＧａＡｓ是ＨｇＣｄＴｅ分子束外延的重要替代衬底材料。用Ｘ双晶衍射和光致发光测试研究了分子束外延生长的ＣｄＴｅ（２１１）Ｂ／ＧａＡｓ（２１１）Ｂ的晶体结构质量，表明外延膜晶体结构完整，具有很高的质量。用高分辨率的透射电镜研究其界面特性，观察到ＣｄＴｅ（２１１）Ｂ相对于ＧａＡｓ（２１１）Ｂ向着［１１１］方向倾斜一个小角度（约３°），界面的四面体键网发生扭曲，由于晶格失配，在界面存在很高的失配位错密度。用二次离子质谱分析仪分析了ＧａＡｓ衬底中的Ｇａ和Ａｓ向ＣｄＴｅ外扩散的情况。结果表明：如果要在ＧａＡｓ衬底上生长ＨｇＣｄＴｅ外延膜，必须先生长一层具有一定厚度的ＣｄＴｅ来阻止Ｇａ和Ａｓ向ＨｇＣｄＴｅ的外扩散和失配位错的延伸。
CdTe/GaAs is an important alternative substract for HgCdTe MBE epitaxy.CdTe(211)B epitaxies have been grown on GaAs(211)B substrates by MBE. The crystal structure quality and perfection were examined by double crystal rocking curve and photo-luminescence measurment.The results showed that the CdTe(211)B epilayers grown under optimized condition could have high quality. High resolution transmitted electron microscope observation of CdTe(211)B/GaAs(211)B interface was carried out.The CdTe(211)B epilayer was found to be tilted with respect to the GaAs(211)B by about 3°toward [111]. The tetrahedral bond network at the interface is distorted.Due to the lattice mismatch.there is g high density of misfit dislocation at the interface.The Ga and As out-diffusion from the GaAs substrate was measutred by SIMS. In or-der to grow the HgCdTe on the GaAs . it is necessary to epitaxy a CdTe baffer layer with a suibable thickness.
关键词
碲化镉
砷化镓
双晶衍射
光致发光
透射电镜
CdTe/GaAs epilayer Double crystal rocking curve Photo lumimscence Transmitted electron microscope SIMS
