SI DIFFUSION IN GAAS AND SI-INDUCED INTERDIFFUSION IN GAAS ALAS SUPERLATTICES/

Various microscopic mechanisms for Si diffusion in GaAs and Si-induced interdiffusion in GaAs/AlAs superlattices are investigated by ab init io molecular dynamics. The dominant mechanism involves the motion of n egatively charged Si-III.V-III pairs through second-nearest-neighbor j umps. This mechanism explains both the ability of Si to disorder super lattices regardless of whether it was introduced during growth or in-d iffused afterwards and the suppression of interdiffusion by compensati on doping. The computed activation energies are in very good agreement with the experimental data.