Adsorption and migration behavior of Si atoms on the hydrogen-terminated diamond (001) surface: A first principles study

Abstract

The adsorption and migration activation energies of a silicon (Si) atom on a hydrogen-terminated diamond (001) surface were calculated using first principles methods based on density functional theory. On the fully hydrogen-terminated surface, the surface carbon atoms possess saturated bonds. The Si atom cannot bond with the surface carbon atoms; thus, the adsorption energy of the Si atom is low. However, on the hydrogen-terminated surface with one or two open radical sites (ORS), the adsorption energy of a Si atom increases to 3.1eV and even up to 4.7eV, thereby forming a stable configuration. Along the three ORS in the direction of dimer row or chain, a Si atom can migrate between two deep basins with migration activation energies at 1.5 or 1.3eV. Given the relatively large energy barrier at approximately 3.8 or 4.7eV, escaping from the deep basin is difficult for the Si atom. This investigation showed that the number and distribution of ORS, namely, the adsorption site of hydrogen atoms and the removal site of surface hydrogen atoms, can affect the adsorption and migration of Si atoms on the hydrogen-terminated diamond surface. Electron structure analysis further reveals that the reactivity of the surface C atoms and the charge transfer amount between the Si and surface C atoms affect the adsorption and migration of Si atoms.