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用改进型垂直布里奇曼法(VMB)生长出的Cd_(1-x)Zn_xTe (X=0.04)梨晶,切成具有单晶的薄片面积大达10～12cm~2,本文还对它代替CdTe用作液相外延生长HgCdTe的衬底,作了评价。与典型的CdTe晶体相比,CdZnTe晶体的缺陷密度较低、机械强度较好,并大大改善了在CdZnTe上生长的HgCdTe液相外延层的宏观与微观形态。CdZnTe衬底上生长的液相外延层的表面形貌表明,它与取向的关系,比在CdTe衬底(取向接近于{111}的平面)上生长的外延层与取向的关系更小。Zn加到CdTe晶格中可以使共价性增加,离子性降低,这样就抑制了范性形变和位错的产生。这些因素的组合能把晶格常数调整到两个极值范围内的任何所需要的值,这样就可以生长高性能红外探测器阵列所要求的低缺陷密度的HgCdTe外延层。通过缺陷腐蚀、红外显微镜检查、X射线摆动曲线分析和X射线形貌测量,对衬底和外延层的质量作了评定。
The Cd_ (1-x) Zn_xTe (X = 0.04) pear crystals grown by the modified vertical Bridgman method (VMB) were cut into single-crystal sheet areas up to 10 ~ 12cm ~ 2. Instead of using CdTe as a substrate for liquid-phase epitaxial growth of HgCdTe, evaluation was made. Compared with typical CdTe crystals, CdZnTe crystals have lower defect density and better mechanical strength, and greatly improve the macroscopic and microscopic morphology of HgCdTe liquid phase epitaxial layers grown on CdZnTe. The surface morphology of the liquid phase epitaxial layer grown on the CdZnTe substrate shows that the orientation of the epitaxial layer grown on the CdTe substrate (the plane oriented {111}) is less dependent on the orientation. The addition of Zn to the CdTe lattice increases covalentness and ionicity, thus inhibiting the formation of the normal deformation and dislocation. The combination of these factors allows the lattice constant to be adjusted to any desired value in both extrema so that the HgCdTe epitaxial layer of low defect density required for high performance infrared detector arrays can be grown. The quality of the substrate and the epitaxial layer was assessed by defect corrosion, infrared microscopy, X-ray rocking curve analysis and X-ray topography.