Complexes which were formed by neutral or charged Ga vacancies, and one or more H atoms, were investigated by using a pseudopotential local density functional approach. Stable and metastable configurations were found, with some H atoms saturating As dangling bonds around the Ga vacancy. In this case, the electronic energy levels of the vacancy, although slightly lowered towards the valence band, remained in the energy gap. When one H atom was located at a bond center position next to a H-decorated vacancy, a donor level appeared in the energy gap. The donor-acceptor pairs, which were formed by this H atom and the Ga vacancy, could account for the low-energy luminescence bands which had been reported for hydrogenated p-type material.

A.A.Bonapasta, M.Capizzi: Physical Review B, 1995, 52[15], 11044-51