A cluster study of aluminum adsorption on Ga-rich GaAs(100)(2 × 1) and β (4 × 2) surfaces

Ab initio self-consistent total energy calculations using second order Møller-Plesset perturbation theory and Hay-Wadt effective core potentials with associated basis sets (HWECP’s) for gallium and arsenic have been used to investigate the chemisorption properties of atomic aluminum on the Ga-rich GaAs(100)-(2 × 1) and β(4 × 2) surfaces. Finite sized hydrogen saturated clusters with the experimental zinc-blende lattice constant of 5.654 Å and the energy optimized Ga dimer bond length of 2.758 Å have been used to model the semiconductor surface. To investigate the effects of the core electrons of aluminum in the adsorption process, we have represented the Al adatom with both HWECP’s and an all electron 6-311++G** basis set. Detailed energetics of chemisorption on the (100) surface, including chemisorption energies, nearest surface neighbor bond lengths, and Mulliken population analysis, have been reported for all considered sites of chemisorption.