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(001)-(2×4) and GaAs(111)B-(√19×√19) or -(2×2) is theoretically investigated. We used empirical interatomic potential and an energy term as a function of the number of electrons remaining in the Ga dangling bonds. The calculated results indicate that the lattice sites on the (001)-(2×4)β2 surface are more favorable for Ga adatoms than those on the (111)B-(√19×√19) and -(2×2) surfaces. This is because the formation of Ga–Ga dimers in the missing dimer rows on the (001)-(2×4)β2 surface suppresses the number of electrons remaining in the Ga dangling bonds. These results suggest that Ga atoms favorably adsorb on the (001) top surface and that Ga atoms impinging on the (111)B side surface basically diffuse to the (001) top surface so long as both top and side surfaces are single-domain structures. This conclusion is consistent with some aspects of other experimental studies.