MICROSCOPIC THEORY OF DIFFUSION ON THE GA SUBLATTICE OF GAAS - VACANCY-ASSISTED DIFFUSION OF SI AND GA

Ga vacancies are believed to mediate self-diffusion of Ga and diffusion of substitutional impurities residing on the Ga sublattice in GaAs. We present results of first-principles calculations for the vacancy-mediated diffusion of Si and Ga. We show that a DX-like mechanism facilitates the migration of lattice site atoms into the interstitial region and that the dangling bonds of a second-nearest-neighbor vacancy assist migration through the interstitial region. Due to these two mechanisms vacancy-assisted diffusion of both Ga and Si occurs with a low-energy barrier.