Stabilization of semiconductor surfaces through bulk dopants

We show by employing density-functional theory calculations (including a hybrid functional) that ZnO surfaces can be stabilized by bulk dopants. As an example, we study the bulk-terminated ZnO (000 (1) over bar) surface covered with half a monolayer of hydrogen. We demonstrate that deviations from this half-monolayer coverage can be stabilized by electrons or holes from bulk dopants. The electron chemical potential therefore becomes a crucial parameter that cannot be neglected in semiconductor surface studies. As one result, we find that to form the defect-free surface with a half-monolayer coverage of hydrogen for n-type ZnO, ambient hydrogen background pressures are more conducive than high vacuum pressures.