碲锌镉晶体中存在着各种典型晶体缺陷, 其缺陷研究一直倍受关注, X射线衍射形貌术是一种非破坏性地研究晶体材料结构完整性、均匀性的有效方法.采用反射式X射线衍射形貌术对碲锌镉衬底的质量进行了研究, 并将衬底的X射线衍射形貌与Everson腐蚀形貌进行了对比分析, 碲锌镉衬底的X射线衍射形貌主要有六种特征类型, 分别对应不同的晶体结构或缺陷, 包括均匀结构、镶嵌结构、孪晶、小角晶界、夹杂、表面划伤, 对上述特征类型进行了详细的分析.目前, 衬底的X射线衍射形貌主要以均匀结构类型为主, 划伤和镶嵌结构缺陷基本已消除, 存在的晶体缺陷主要以小角晶界为主.通过对比分析碲锌镉衬底和液相外延碲镉汞薄膜的X射线衍射形貌, 发现小角晶界等晶体结构缺陷会延伸到外延层上, 碲锌镉衬底质量会直接影响碲镉汞外延层的质量, 晶体结构完整的衬底是制备高质量碲镉汞外延材料的基础.

Many kinds of typical crystal defects can be observed in the Cadmium Zinc Telluride (CdZnTe) single crystals. X-ray diffraction topography is a powerful method for investigating the structural integrity and homogeneity of single crystals. In this paper, the defects of CdZnTe substrate and Mercury Cadmium Telluride (MCT) epitaxial layer grown by liquid phase epitaxy (LPE) were investigated by X-ray diffraction topography in reflection. The X-ray diffraction topography and etched surface morphology of the same substrate were compared to characterize the defects. Six types of X-ray diffraction topography of defects in the CdZnTe substrate were observed including perfect structure, mosaic structure, twin crystals, low-angle grain boundary, inclusions/precipitates, and scratches. At present, most of the X-ray diffraction topographies of the samples show perfect structure of the CdZnTe substrates, free of scratches and mosaic structure defects. Low-angle grain boundary is the major type of defects in the CdZnTe substrates. Comparing the X-ray diffraction topography of CdZnTe substrate and MCT epitaxial layer grown on the same substrate by LPE, the low-angle grain boundary defects on the substrate were also observed on the MCT epitaxial layer. These results suggested that the quality of MCT epitaxial layer was closely related to the defects of CdZnTe substrate. The substrate with perfect structure was the foundation for the growth of MCT epitaxial layer with high quality.