  Ab initio molecular dynamics simulations are employed to investigate the
dominant migration mechanism of the gallium vacancy in gaas as well as to
assess its free energy of formation and the rate constant of gallium
self-diffusion. our analysis suggests that the vacancy migrates by second
nearest neighbour hops. the calculated self-diffusion constant is in good
agreement with the experimental value obtained in ^69 GaAs/ ^71 GaAs isotope
heterostructures and at significant variance with that obtained earlier from
interdiffusion experiments in GaAlAs/GaAs-heterostructures.
