Theoretical investigations of adatom adsorptions on the As-stabilized GaAs(1 1 1)A surface

We investigated adsorptions of Ga and As atoms on the As-stabilized GaAs(1 1 1)A surface by using first-principles calculations. We found that a single As adatom does not occupy the As lattice site on the surface, but the As lattice site becomes active for an As adatom when the As adatom couples with Ga adatoms. This finding indicates that Ga has a self-surfactant effect on the As-stabilized surface. We also found that adatoms do not form stable microstructures on the As-stabilized surface. This is consistent with the reported experimental results that the layer-by-layer growth is difficult. We discuss epitaxial growth processes based on the calculation results.