Growth of high quality CdZnTe (133) epilayers on GaAs (211) substrate with Zn1−xCdxTe/ZnTe buffer layer by close spaced sublimation

Abstract

The Cd0.96Zn0.04Te (211) crystal is widely recognized as the optimal substrate for epitaxy growth of HgCdTe material. However, its further application is significantly hindered by size and cost limitations. CdZnTe films grown on GaAs substrates by close spaced sublimation may present a promising substrate for epitaxial HgCdTe. In this work, we successfully prepared high quality CdZnTe (133) films on GaAs (211) substrate. The results of scanning transmission electron microscope and selected-area electron diffraction reveals different crystal orientation between GaAs and CdZnTe, which can effectively accommodate the large lattice mismatch. The crystalline quality of the CdZnTe film was improved by introducing a ZnTe buffer layer, resulting in reduction in the etch pit density from 3.2 × 105 to 2.6 × 105 cm−2; a decrease in the full width at half maximum from 57 to 34″, and a lower surface roughness from 9.88 to 3.69 nm. The incorporation of the ZnTe buffer layer prompt the formation of CuPt-type ordered CdZnTe regions at the interface between the CdZnTe film and ZnTe, efficiently relieving the misfit strain originating from GaAs and ZnTe interface. Additionally, a two-step growth method was employed to adjust the Zn content of the film surface by controlling the growth temperature. Diverse lattice constant CdZnTe film is ready to further epitaxial growth of HgCdTe material with different bandgap.