用高分辨透射电镜对MOCVD生长的ZnSe1-xSx-ZnSe应变超晶格结构的研究

本文利用高分辨电子显微镜(TEM)从原子尺度对MOCVD生长的ZnSe_1-xS_x-Znse应变超晶格的精细结构进行了细致观察.通过对缺陷的种类、分布的分析提出缺陷的产生原因与过渡层质量有直接关系,通过改善过渡层的成份及各层间的厚度可制备出结构较完整以及较平整的超晶格薄层材料.

THE STUDY OF LATTICE STRAIN AND STRUCTURE ON ZnSe-ZnS STRAINED-LAYER SUPERLATTICES USING HIGH RESOLUTION TRANSMISSION ELECTRON MICROSCOPY

Fine structural properties of ZnSe1-xS2-ZnSe strained-layer superlattices grown onGaAs (100) substrates by MOCVD were investigated by high resolution transmission electron microscope. Examination of the type and distribution of the defects has revealed that the appearance of defects has relation with the quality of buffer layer. The superlat-tices material that have smooth structure has been prepared by improving the composition of the buffer layer and the thickness of each layer of the superlattice.The superlattice quality was intensely dependent on the substrate surface and buffer layer surface. The superlattice grown on smooth buffer layer has smooth surface, and grown on poor buffer layer has poor quality ,and has more defects.The critical layer thickness of ZnS epitaxy grown on smooth GaAs substrate is 2nm,it is slightly bigger than that theortically.The crystalline defects are found to be concentrated in the ZnS layers. It is found that mainly, the ZnS lattice constants change to match with the ZnSe lattice.The imperfection of superlattice structure also shows that there exists a great number of interface steps that make sublattices suspended.In atmospheric pressure growth the interface of ZnSe and ZnS layer exists some deep mutual diffused layer that makes the interface lattice image vague and, indistinct.