STRUCTURE AND DYNAMICS OF HYDROGENATED GAAS(110) AND INP(110) SURFACES

We have investigated the structural and vibrational properties of hydrogen-covered GaAs(110) and InP(110) surfaces in the framework of the density-functional theory. The plane wave pseudopotential method combined with the slab supercell description for the surfaces has been employed to determine the relaxation geometries of H:GaAs(110) and H:InP(110) for the half- and one-monolayer coverages. Our results are in good agreement with all available experimental data. For both surfaces and for all coverages we have determined the surface vibrations by means of an nb initio linear-response formalism. The calculated bond-stretching frequencies compare very well with the results from high-resolution electron-energy-loss spectroscopy. The half-monolayer coverages on InP(110) exhibit vibrational states which are related to the mechanism which leads to the structural decomposition of the surface experimentally observed at high hydrogen exposures.