HgCdTe分子束外延薄膜的应变弛豫

STRAIN AND RELAXATION OF MBE-HgCdTe FILMS

对不同衬底上外延生长的HgCdTe薄膜进行了倒易点二维图测试 ,分析了外延层与衬底之间的结构取向关系以及晶格常数的失配现象 .通过测定Cd1-yZnyTe衬底上的HgCdTe外延层的应变弛豫状况 ,获得了晶格匹配条件时衬底Zn组分的准确值 .实验结果还表明 :HgCdTe外延层与晶格失配的衬底之间存在着倾角 ,该倾角随失配度的增大而增大 ;当衬底失配度较小时 ,非对称倒易点二维图显示外延层并不处于全应变状态 ,而是处于应力部分释放状态 ;相反 ,当外延层晶格失配产生的应力全部释放时 ,外延层包含着较大的失配位错 ,摇摆曲线半峰宽展宽较大 .

The tilt relation and lattice misfit phenomenon between MBE-HgCdTe layers and different substrates were studied by employing reciprocal lattice mappings technology. The precise fit zinc composition in Cd1-yZnyTe substrates was determined by analyzing the elastic deformation in MBE-HgCdTe layers. The result shows that MBE-HgCdTe epitaxial layers and substrates are tilted with respect to each other, and the tilt angle increases with the lattice mismatch. In the case of little mismatch between substrate and layer, the layer is strained with partially relaxation of stress. While the layer is full relaxed, the lattice mismatch becomes large. In this case, the HgCdTe layers have more misfit dislocations and larger width of half maximum.