Photoluminescence spectroscopy was used to determine the nature of a near-infrared emission, with a no-phonon line at 0.88eV, which was common in the electron-irradiated nitride. This emission was suggested to arise from an internal transition between a moderately shallow excited state (with an ionization energy of about 0.021eV) and the deep ground state (with an ionization energy of about 0.90eV) of a deep defect. The existence of a second higher excited state which was related to the 0.88eV centre was also indicated by temperature-dependent studies. Differing electronic characters of the wave functions which were related to the first and second excited states were revealed by photoluminescence polarization measurements Since the photoluminescence emission was observed, at comparable intensity, in all electron-irradiated samples – regardless of doping - it was proposed that native defects, common residual contaminants or their complexes were involved. The substitutional ON donor (or related complex) was considered to be the most probable candidate, on the basis of a marked similarity between the local vibrational properties of the 0.88eV centres and the substitutional OP donor in GaP.

Electronic Structure of the 0.83eV Luminescence Center in Electron-Irradiated Gallium Nitride I.A.Buyanova, M.Wagner, W.M.Chen, N.V.Edwards, B.Monemar, J.L.Lindström, M.D.Bremser, R.F.Davis, H.Amano, I.Akasaki: Physical Review B, 1999, 60[3], 1746-51