Theoretical investigations of adatom behavior on non-planar surfaces with GaAs(n 1 1)A

The behavior of Ga and As adatoms on non-planar surfaces consisting of GaAs(0 0 1)-(2 4)b2 top and GaAs(n 1 1)A (n = 2, 3 and 4) facet surfaces are investigated by empirical interatomic potentials with the aid of ab initio calculations. The calculated results imply that Ga adsorption energies strongly depend on the surface orientation, whereas As adsorption energies keep almost constant. The difference in adsorption energies can be interpreted by considering strain energy. In particular, Ga adatom is stabilized on the (3 1 1)A surface by the smallest strain energy forming interatomic bonds with three As atoms located at the regular fcc sublattice. Furthermore, we roughly simulate resultant surface profile of GaAs thin films on non-planar surface consisting of the (0 0 1)-(2 4)b2 top and (n 1 1)A facet surfaces based on the rate equation. The simulated results reveal that the non-planar surface consisting of the (0 0 1)-(2 4)b2 top and (3 1 1)A facet surfaces forms unique surface profile because of preferential Ga adsorption on the (3 1 1)A and Ga migration from the (0 0 1)-(2 4)b2 toward (3 1 1)A. Consequently, growth on the (3 1 1)A facet surface exhibits a unique cross sectional surface profile compared with that on the non-planar surfaces consisting of (2 1 1)A and (4 1 1)A facet surfaces.