Theoretical estimation of the energy differences among OH-, F-, and H-terminations of the Si surface

Energy changes during the conversion reaction among OH-, F-, and H-terminated Si surfaces have been evaluated by first-principles calculations with the density functional theory and the reaction field method for solvent effect. First, the reaction paths for the conversion of surface terminating species were examined in terms of the interactions with HF or H2O and, next, the potential energy curves were estimated, incorporating the effect of the solvent. It was suggested that the OH-termination is easily converted into the F-termination and the reverse reaction also possibly occurs at room temperatures, whereas the conversion between the H- and OH-terminations is not probable. The replacement of F by H is not favorable, and instead, Si etching would be required for the generation of the H-terminated surface.