In_(0.25 )Ga_(0.75)As/GaAs应变异质结的离子沟道分析

Ion Channeling Analysis of In_(0.25)Ga_(0.75)As/GaAs Strained Heterojunction

本文采用Li离子作为背散射-沟道实验的分析束来研究In_(0.75)Ga_(?)As/GaAs应变异质结的结构.沟道效应和角扫描的实验表明,由于晶格失配,异质结的点阵发生应变,晶格常数在生长方向产生～0.04A的拉伸或压缩,于是离子沟道在<110>倾斜方向发生0.9°的扭折,导致沿这个方向的严重退道.对较厚外延层的样品,除应变结构外,在生长过程中还形成失配位错结构及其他点阵缺陷,从而产生附加的退道。

The structure of In_(0.25)Ga_(0.75)As/GaAs strained heterojunction is investigated by meansof Li ion beam analysis.Channeling and an gular scan measurements suggest that latticestrain occurs in the interface because of the lattice mismatch between the lattice constants ofIn_(0.25)Ga_(0.75)As and GaAs.There is an expansion and contraction of the equilibrium latticeconstant of about 0.04 A in the interface,these stresses cause tetragonal distortions of 0.9°. Ab-normally high dechanneling is observed due to the presence of this lattice strain.Lattice-defects in the epitaxial layer also give rise to a significant dechanneling.