The migration potentials of Ga adatoms near to step edges on the c(4 x 4) 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