The absolute formation energies of native defects were calculated. It was found that the formation energies, and thus the equilibrium concentrations of the defects, depended strongly upon the atomic chemical potentials of As and Ga as well as upon the electron chemical potential. Thus, the Ga vacancy concentration changed by more than 10 orders of magnitude as the chemical potentials of As and Ga varied over the thermodynamically possible range. It was concluded that the rate of self-diffusion depended markedly upon the surface annealing conditions, and that impurity-enhanced self-diffusion involved VGa3- under As-rich n-type conditions, or Gai3 under Ga-rich p-type conditions.

S.B.Zhang, J.E.Northrup: Physical Review Letters, 1991, 67[17], 2339-42