Hg_(1-x)Cd_xTe分子束外延薄膜晶格参数与组分关系的研究

Relationship between lattice parameters and compositions of molecular beam epitaxial Hg_(1-x)Cd_xTe films

高分辨率x射线衍射技术被应用于Hg1-xCdxTe分子束外延薄膜晶格参数的测量及其晶格应变状态的研究,研究发现Hg1-xCdxTe分子束外延薄膜内既存在正应变也存在剪切应变.通过应用晶体弹性理论,对Hg1-xCdxTe分子束外延薄膜的应变状态进行了定量的分析与计算,获得了Hg1-xCdxTe分子束外延薄膜在完全弛豫状态下的晶格参数,从而得到了Hg1-xCdxTe分子束外延薄膜晶格参数与组分的关系,该关系符合Vegard’s定律,而不是早期研究所给出的Higgins公式.研究还发现,根据对称衍射测量所得到的(224)晶面间距,可直接计算出Hg1-xCdxTe分子束外延薄膜晶格参数,并用Vegard’s定律确定组分的方法,可作为估算Hg1-xCdxTe分子束外延材料组分的常规技术,其组分的测量误差在0·01左右.

High-resolution x-ray diffraction technology. is applied to the measurement of lattice parameters and the study of strain for Hg1-xCdxTe films grown by molecular beam epitaxy. The results show that there exist both perpendicular strain and shear strain in Hg1-xCdxTe films. Based on crystal elastic theory, strain states in Hg1-xCdxTe films are analyzed and calculated, and the lattice parameters of Hg1-xCdxTe films at the relaxation state are obtained. It is found that the relationship between lattice parameters and compositions of Hg1-xCdxTe films agrees with Vegard' s law, rather than Higgins formula proposed in earlier research. It is also found that the lattice parameters can be derived from the measured data of (224) plane spacing, and that the compositions of Hg1-xCdxTe films can also be evaluated by using Vegard' s law with an error about 0. 01.