APPLICATION OF THE CHARGED POINT-DEFECT MODEL TO DIFFUSION AND INTERDIFFUSION IN GAAS

Diffusion and interdiffusion in GaAs and GaAs/AlGaAs superlattices are shown to be consistent with the charged point-defect model. The charged Ga vacancies V3-Ga and interstitials I2+ Ga appear to control group II, III, and probably V element diffusion. After adjustment for carrier concentration and As pressure, these elements are found to have a nearly identical intrinsic diffusivity and activation energy over a wide range of temperature. A natural consequence of Ga diffusion via negative or positive point defects is that enhanced group-III interdiffusion is expected with either n- or p-type doping. Anomalous enhancements in group-II dopant diffusivity have been related to the supersaturation of Ga interstitials.