It was recalled that it had recently been found that H in the C vacancy of SiC formed a 3-center bond with two Si neighbors in the vacancy, and gave rise to a new electrically

active state. The behavior of H in the anion vacancies of BN, AlN and GaN was examined here. It was found that 3-center bonding of H was quite common and followed clear trends in terms of the second-neighbor distance in the lattice, the typical (2-center) H–host-atom bond length, the electronegativity difference between host atoms and H, as well as the charge state of the vacancy. The 3-center bonding limited the number of H atoms, which a N vacancy could capture, to 2 and also prevented electrical passivation in GaAs.

Physics and Chemistry of Hydrogen in the Vacancies of Semiconductors. B.Szûcs, A.Gali, Z.Hajnal, P.Deák, C.G.Van de Walle: Physical Review B, 2003, 68[8], 085202 (10pp)