THEORY OF SELF-DIFFUSION IN GAAS

Ab initio molecular dynamics simulations are employed to investigate t he dominant migration mechanism of the gallium vacancy in GaAs as well as to assess its free energy of formation and the rate constant of ga llium self-diffusion. Our analysis suggests that the vacancy migrates by second-nearest neighbour hops. The calculated self-diffusion consta nt is in good agreement with the experimental value obtained in (GaAs) -Ga-69/(GaAs)-Ga-71 isotope heterostructures and at significant varian ce with that obtained earlier from interdiffusion experiments in GaAlA s/GaAs-heterostructures.