Structure and Passivation effects of mono- and di-hydrogen complexes in GaAs(y)N(1-y) alloys

In GaAsyN1–y, the presence of a few percent of N induces a large reduction of the GaAs band gap that vanishes upon hydrogenation. In the present Letter, the energetics of N-H complexes and their effects on the band structure of the GaAs0.97N0.03 alloy have been investigated by first-principles density functional methods. We find that monohydrogen N–H+ and dihydrogen N–H2* complexes are formed depending on doping. Moreover, only N–H2* complexes account for the neutralization of nitrogen effects. A model is proposed that clarifies the passivation mechanism of nitrogen by H.