H-induced passivation of GaAs(110)-Be surface-acceptor systems

Complete neglect of differential overlap cluster calculations have been performed for ${\mathrm{H}}^{+}$ on a clean GaAs(110) surface. The results demonstrate that ${\mathrm{H}}^{+}$ 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 ${\mathrm{H}}^{+}$ 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.