HgCdTe／CdZnTe晶格失配与X光衍射貌相的关系研究

文章采用富Te水平推舟液相外延工艺在CdZnTe衬底上生长了HgCdTe外延薄膜。研究了外延薄膜／衬底晶格失配度、X光衍射貌相、红外焦平面器件探测率三者之间的关系。对于HgCdTe外延层的X光衍射貌相我们将其大致分为五类，分别是Crosshatch貌相、混合貌相、均匀背景貌相、Mosaic貌相以及由衬底质量问题引起的沟壑状貌相，采用Crosshatch貌相和混合貌相材料所制备的红外焦平面器件，平均来说其探测率(D*)较高。X射线双轴衍射的实验结果表明，当外延层与衬底的晶格失配度为～0.03％时，外延层会呈现明显的Crosshatch貌相；而当失配度减小时，会逐渐呈现出混合貌相、均匀背景貌相、直至失配度为负值时呈现Mosaic貌相。因此，对于特定截止波长的HgCdTe焦平面器件，可以通过控制HgCdTe／CdZnTe之间的失配，生长出符合我们要求的貌相的碲镉汞外延材料，从而来提高焦平面器件的性能。

Relationship between Lattice Mismatching and X ray Topography of HgCdTe/CdZnTe

The HgCdTe layers were grown by Te rich liquid phase epitaxy in a horizontal slider system. The relationship among the lattice mismatching of HgCdTe/CdZnTe, the X ray topography and the detectivity(D*) of the IRFPA was studied. For HgCdTe layer of X ray diffraction topography,we will classify it roughly into five categories: Crosshatch pattern, mixing pattern, uniform background pattern, mosaic pattern as well as by the quality of the substrate induced ravine topography, the Crosshatch pattern and the mixing pattem materials prepared for IRFPA have higher detectivity on average. The results of X ray diffraction show that when the lattice matching of HgCdTe/CdZnTe about 0.03% ,the Crosshatch pattern appears clearly;When the lattice matching of HgCdTe/CdZnTe reduced, the Crosshatch pattern become into mixing pattern, uniform background pattern gradually and when the epilayer lattice parameter is smaller than that of the substrate(negative mismatch),the Crosshatch changes into a Mosaic structure. Therefore, for the specific cutoff wavelength devices, if we want to enhance the detectivity of the IRFPA, we can control the lattice matching of HgCdTe/CdZnTe in order to grown the epitaxy materials of meeting our requirements.