The migration potentials of Ga adatoms near to kink and step edges were qualitatively investigated by using empirical inter-atomic potentials and an energy term. The latter term, as a function of the number of electrons that remained in the Ga dangling bond, was deduced from first-principles pseudopotential calculations. The calculated results implied that the lattice sites in the missing dimer row were favorable for Ga adatoms on the GaAs(001)-(2x4)2 surface. This was because the formation of Ga dimers reduced the number of electrons that remained in Ga dangling bonds. Lattice sites in the missing dimer row, near to a kink and a B-type step edge, were stable locations for a Ga adatom. On the other hand, no preferential adsorption site was found near to an A-type step edge. This was because a Ga adatom in the missing dimer row near to a kink and a B-type step edge was slightly stretched by an As atom and As-dimer on the plane that was 1 layer below, rather than being strongly stretched by two As-dimers near to an A-type step edge.

T.Ito, K.Shiraishi: Japanese Journal of Applied Physics, 1996, 35[2-8A], L949-52