H-INDUCED PASSIVATION OF GAAS(110)-BE SURFACE-ACCEPTOR SYSTEMS

Complete neglect of differential overlap cluster calculations have been performed for H+ on a clean GaAs(110) surface. The results demonstrate that H+ prefers to bond with the surface As atom rather than the surface Ga atom. Investigation of a microscopic model for hydrogen (H)-induced passivation on p-type GaAs(110) surfaces, where a surface Ga atom is replaced by a Be acceptor atom, also shows that, in equilibrium, the H atom attaches itself to the dangling bond of the As atom next to the Be atom. Passivation occurs due to compensation when the H atom captures a free hole to form H+ which then subsequently finds the As atom next to the acceptor. This microscopic model may account for the As-H stretching lines observed in infrared experiments as well as for the absence of Ga-H lines.