ZnSe/GaAs Heterointerface Stabilization by High-Temperature Se Treatment of GaAs Surface

Abstract

An Se treatment of Ga-terminated (001) GaAs substrate surfaces at temperatures as high as 500°C greatly reduces the diffusion of Ga and As atoms into a ZnSe epitaxial layer during growth. High-temperature Se treatment forms several monolayers of GaAsSe on the GaAs surface. The GaAsSe layer are so thermodynamically stable that Ga atoms are bonded tightly with Se atoms at the heterojunction and diffuse very little into the ZnSe layer, Reflection high energy electron diffraction patterns become streaky at the beginning stages of growth, presumably due to the suppression of diffusion. In order to obtain a high-purity ZnSe layer with less vacancy concentration, a combination of high-temperature (∼500°C) Se treatment and low-temperature (∼300°C) growth is proposed.