Hydrogenation-induced energy gap of the As-terminated GaAs(100) surfaces.

Abstract

First-principles total-energy calculations have been done for cases of monolayer-hydrogen adsorption on the As-terminated GaAs(100) surface. Two different geometries are considered as candidates for the stable geometry, one of which has been found to be metallic while the other has been found to be nonmetallic. The nonmetallic surface is more stable than the metallic surface despite the larger (smaller) number of dangling (chemical) bonds on the surface. The electronic properties and the order of the total energies of these two geometries are consistent with a prediction based on the electron-counting model, which is helpful to describe the atomic and electronic structures of pristine GaAs surfaces. We have concluded that the electron-counting model is also applicable in cases of hydrogen adsorption on GaAs surfaces.