Total-energy density functional calculations were performed, using first-principles pseudopotentials in order to determine the atomic and the electronic structures of the anion vacancy on the (110) surface. An inward relaxation of the 3 neighboring In atoms next to the anion vacancy was obtained, but the stable atomic structure depended critically upon the vacancy charge-state. The +1 charged vacancy exhibited a non-symmetrical configuration, with one re-bonded dimer, while both 0 and –1 charged vacancies exhibited a symmetrical configuration with loosely re-bonded and re-bonded trimers, respectively. The –1 charge state was stable over the whole band gap. In contrast to the bulk, the surface vacancy was a positive-U center. Three vacancy states, one deep within the valence band and 2 around the band gap, were identified. The results showed that the character of the vacancy states was depended mainly upon the atomic configuration.

Atomic and Electronic Properties of Anion Vacancies on the (110) Surfaces of InP, InAs and InSb. M.C.Qian, M.Göthelid, B.Johansson, S.Mirbt: Physical Review B, 2002, 66[15], 155326 (9pp)