Changes in interdiffusion associated with thermally oxidized GaAs

Thermal oxidation and subsequent processing steps were found to significantly affect interdiffusion in AlGaAs/GaAs quantum wells. GaAs layers were grown on top of the quantum wells and oxidized at 450 C, and this was followed with a nonoxidizing ambient during annealing at 950 C. The resulting oxide, largely composed of Ga₂O₃, affects the native defect concentration and interdiffusion rate. Low temperature photoluminescence demonstrated that the oxidation plus annealing process significantly increased the rate of interdiffusion relative to structures which were annealed but not oxidized. However, when oxide layers covered with Al were annealed at 950 C, the Ga₂ O₃ was reduced and Ga interstitials were forced into the GaAs. Using Al layers of various thickness, different quantities of Ga interstitials were injected into the epitaxial layer and a consistent reduction in interdiffusion was related to the Al layer thickness. The results are found to be consistent with previously a proposed model of interdiffusion controlled by Ga vacancies