Hydrogen-induced states near the GaAs band edges

In the present study the link between the inclusion of H species in GaAs an d the appearance in the band gap of near-band-edge energy levels has been i nvestigated. The equilibrium geometries and the electronic structures relat ive to different locations of H atoms, ions, and dimers in the GaAs lattice have been evaluated by first-principle local-density-functional methods. A tomic arrangements in GaAs identical to those found for different equilibri um geometries of the H species, but with the H species removed, have also b een investigated in order to separate the effects of the lattice deformatio ns due to the H inclusion from those produced by the formation of H-host-at om bonds. Discrete near-edge levels appear in the band gap, which are induc ed by the H interactions with the GaAs lattice as well as by charge effects in the case of H ions. Finally, radiative transitions from the conduction- band to the valence-band near-edge states are shown to account for the main features of the emission bands observed in the photoluminescence spectra o f hydrogenated III-V compounds.