Mechanisms of doping-enhanced superlattice disordering and of gallium self-diffusion in GaAs

Abstract

Recently available Ga-Al interdiffusion results in GaAs/AlAs superlattices allow us to conclude that Ga self-diffusion in GaAs is carried by triply negatively charged Ga vacancies under intrinsic and n-doping conditions. The mechanism of the Si-enhanced superlattice disordering is the Fermi-level effect which increases the concentrations of the charged point defect species. For the effect of the p dopants Be and Zn, the Fermi-level effect has to be considered together with dopant diffusion induced Ga self-interstitial supersaturation or undersaturation. Self-diffusion of Ga in GaAs under heavy p-doping conditions is governed by positively charged Ga self-interstitials.