The behavior of H in crystalline material was examined by using theoretical techniques which were based upon the pseudopotential density functional method and a super-cell geometry. Stable sites, migration paths, and barriers for different charge states were explored and were displayed as total-energy surfaces which provided an immediate insight into these properties. The bond-center site was a global minimum for the neutral and positive charge states. In the negative charge state, the tetrahedral interstitial site was preferred. The positive charge state was energetically favorable in p-type material and provided a mechanism for the passivation of shallow acceptors. Electrons from the H atoms annihilated the free holes, and the formation of H-acceptor pairs followed compensation. Also considered were molecule formation and H-induced damage. A number of different mechanisms for defect formation were examined, and H-assisted vacancy formation was found to be an exothermic process.

C.G.Van de Walle, P.J.H.Denteneer, Y.Bar-Yam, S.T.Pantelides: Physical Review B, 1989, 39[15], 10791-808