Point defects, diffusion mechanisms, and superlattice disordering in GaAs-based materials
We discuss mechanisms of Ga self-diffusion and impurity diffusion in GaAs, and of disordering enhancement in GaAs/AlGaAs superlattices. Ga self-diffusion and Ga-Al interdiffusion are governed by VGa3- under instrinsic and n-doping conditions, and by IGa2+ under heavy p-doping conditions. The responsible mechanisms for enhancing superlattice disordering is the Fermi-level effect for the n-dopants Si and Te, and are the combined effects of the Fermi-level and the dopant diffusion induced non-equilibrium point defects for the p-dopants Zn and Be. For n-type GaAs the donor Si atoms diffuse primarily also via VGa3- for p-type GaAs the interstitial-substitutional impurities Zn and Be diffuse via the kick-out mechanism and induce an IGa2+ supersaturation and undersaturation, respectively, under indiffusion and out-diffusion conditions.
