Effects of (NH4)2Sx-Pretreatment of GaAs Surfaces on Properties of Epilayers and Heterointerfaces in Pseudomorphic ZnSe/GaAs Gown by MOMBE

Publisher Website
Google Scholar
Abstract
We investigated the effects of (NH4)2S x -pretreatment of GaAs substrates on the properties of ZnSe epilayers and heterointerfaces in pseudomorphic ZnSe on GaAs by MOMBE. Compared to the pretreatment of GaAs substrates by a conventional method where thermal etching is employed as a cleaning process, (NH4)2S x -pretreatment resulted in (i) two-dimensional growth from an earlier stage of growth, (ii) better optical properties of pseudomorphic ZnSe epilayers, and (iii) better heterointerfaces. Thus, the interface state density near an energy level of 0.18 eV from the top of the valence band is estimated to be about 5×1011 cm-2·eV-1, and the density near the midgap is below the lower detection limit of Terman's method without post-annealing. These features show that this pretreatment technique is very promising for the fabrication of high-quality heterojunction devices.