A THEORETICAL INVESTIGATION OF THE POTENTIAL FOR INTER-SURFACE MIGRATION OF GA ADATOMS BETWEEN GAAS(001) AND (111)B SURFACES

The potential for inter-surface migration of Ga adatoms between GaAs(0 01)-(2x4) and GaAs(111)B-(root 19 x root 19) or -(2 x 2) is theoretica lly investigated. We used empirical interatomic potential and an energ y term as a function of the number of electrons remaining in the Ga da ngling bonds. The calculated results indicate that the lattice sites o n the (001)-(2 x 4)beta 2 surface are more favorable for Ga adatoms th an those on the (111)B-(root 19 x root 19) and -(2x2) surfaces. This i s because the formation of Ga-Ga dimers in the missing dimer rows on t he (001)-(2x4)beta 2 surface suppresses the number of electrons remain ing in the Ga dangling bonds. These results suggest that Ga atoms favo rably adsorb on the (001) top surface and that Ga atoms impinging on t he (111)B side surface basically diffuse to the (001) top surface so l ong as both top and side surfaces are single-domain structures. This c onclusion is consistent with some aspects of other experimental studie s.