Ga-adatom-induced As rearrangement during GaAs epitaxial growth: Self-surfactant effect

GaAs(001) surfaces, on which epitaxial growth is widely performed, generally contain either missing dimer rows or excess As ad-dimers and As coverage is not equal to 1.00. We investigated theoretically how layer-by-layer growth is maintained on GaAs(001) surfaces by controlling the excess and deficiency of surface As atoms. Our calculations indicate that preadsorbed Ga atoms act as “self-surfactant atoms” and induce the As rearrangement on the surface during GaAs epitaxial growth. We show that this effect originates from the band-energy stabilization of the surfaces.