Defects and defect identification in group III-nitrides

In this paper the shallow donors oxygen and silicon in GaN and AlGaN and the problem of DX formation are reviewed. New experimental results obtained by optically detected magnetic resonance are presented which clarify the behavior of Mg acceptors in GaN. The properties of the violet, yellow and red luminescence bands in GaN are also briefly commented on. Transition metal ions which are residual contaminants give rise to sharp zero-phonon lines in the near infrared followed by phonon sidebands. Their charge and spin states as well as the chemical identity are in part revealed by electron paramagnetic resonance and detailed magneto-luminescence experiments.