The migration potentials of Ga adatoms near to step edges on the c(4x4) surface were investigated by using an empirical interatomic potential and an energy term that accounted for charge redistribution on the surface. The energy term, as a function of the number of electrons which remained in the Ga dangling bonds, was deduced from first-principles calculations. The latter results implied that lattice sites along the A-type step edges were stable for Ga adatoms, whereas no preferential adsorption site was found near to B-type step edges. This was because the number of electrons which remained in the Ga dangling bond was reduced by Ga adatoms that occupied lattice sites along A-type step edges, rather than being unchanged by those which occupied lattice sites near to B-type step edges.

T.Ito, K.Shiraishi: Japanese Journal of Applied Physics, 1996, 35[2-8B], L1016-8