Effects of hydrogenation on the electronic properties of dilute nitrides

This chapter reviews the effects that hydrogen incorporation produces on the electronic properties of dilute nitrides, as determined by optical spectroscopy experiments. In the first instance, H brings the band gap energy of Ga(AsN) and related materials back to that of the N-free host material. This dramatic finding is due to the "electronic passivation" of N atoms by H atoms following the formation of specific N-H complexes. These complexes can be progressively and controllably deactivated by either thermal, electron, or optical treatments. Nitrogen passivation involves the entire band structure of dilute nitrides and causes a tunable variation of the transport (electron mass) and spin (electron gyromagnetic factor) properties. The application of magnetic fields and hydrostatic pressures combined with the effects of hydrogenation permits to unveil an electronic hierarchy between different N clusters that contribute to a different extent to determining the puzzling compositional dependence of the physical properties of these fascinating materials.