Atomistic Mechanisms of Dopant-Induced Multiple Quantum Well Mixing and RelatedPhenomena

摘要

We discuss mechanisms of Gallium self diffusion and impurity diffusion in GalliumArsenide, and of layer mixing enhancement in GaAs/AlGaAs multi quantum wells (MQW). Ga self diffusion and Ga-Al interdiffusion are governed by the triply-negatively-charged Ga vacancies, V Ga under intrinsic and n doping conditions, and by doubly positively charged Ga self interstitials, I Ga, under heavy p doping conditions. The responsible mechanisms for enhancing MQW mixing 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 points defects for the p-dopants Zn and Be. For n-type GaAs the donor Si atoms diffuse primarily also via VGa. For p-type GaAs the interstitials-substitutional impurities Zn and Be diffuse via the kick out mechanism and induce a supersaturation and an undersaturation in the concentrations of IGa respectively under in diffusion and out diffusion conditions.