A theoretical investigation of migration potentials of Ga adatoms near step edges on GaAs(001)-c(4x4) surface

Migration potentials of Ga adatoms near step edges on c(4 x 4) surface are investigated using the empirical interatomic potential and an energy term due to the charge redistribution on the surface. The energy term; as a function of the number of electrons remaining in the Ga dangling bonds, is extracted from ab initio calculations. The calculated results imply that the lattice sites along A-type step edges are stable for Ga adatoms, whereas no preferential adsorption site is found near B-type step edges. This is simply because the number of electrons remaining in the Ga dangling bond is suppressed by Ga adatoms occupying lattice sites along A-type step edges as opposed to being unchanged by those occupying lattice sites near B-type step edges.