Theoretical investigations of stable growth sites on GaAs(001) surfaces

The stable growth sites on GaAs(001) surfaces are discussed through calculation of migration potentials near steps and kinks using an energy formalism which incorporates the strain and electronic energy contributions based on the empirical interatomic potentials and the electron counting model. On the (2 × 4)β2 surface, lattice sites near a B-type step edge are stable for a Ga adatom, whereas no preferential adsorption site is found near an A-type step edge. Opposite qualitative trends were found in the calculations on the c(4 × 4) surface. Moreover, according to the energy formalism, an electron counting Monte Carlo (ECMC) simulation was applied to investigate the role of As-dimer kink sites in thin-film growth. Adatoms impinging on the (2 × 4)β2 surface predominantly occupy the kink sites in the missing dimer region. These calculated results are discussed in terms of strain energy and the electron counting model.