Density functional studies of surface potentials for hydrogen and oxygen atoms on diamond (111) surfaces

Abstract

The adsorption of hydrogen and oxygen atoms on diamond (111)-(1 × 1) surfaces is investigated by a molecular orbital method based on the density functional theory. The potential energy for hydrogen and oxygen adatoms on a flat surface and a surface with monoatomic steps are studied. The oxygen adatom is found to have a much lower energy barrier for migration than the hydrogen adatom. On the basis of the variations of potential energy, surface diffusion coefficients of adatoms are calculated. The potential energy for the oxygen adatom is much lowered near the step edge in comparison with those on flat regions. It is suggested that the oxygen atoms adsorbed on the diamond (111) surface are preferentially trapped near atomic steps after migration.