Irradiation of p-type (Mg-doped) GaN in situ at 4.2K, by 2.5MeV electrons, reduced the visible luminescence and created a broad luminescence band in the infra-red at about 0.95eV. Upon annealing at 180K, partial recovery of the visible luminescence occurred and a well-resolved S = 1 center (L8) was observed by optical detection of electron paramagnetic resonance. Its D tensor suggested a Frenkel excitonic state with the two S = 1/2 particles separated along the off c-axis Ga-N bond direction by the Ga-N bond distance. Other centers were weakly observed, in the infra-red band, which annealed out at room temperature.

Defects Observed by Optical Detection of Electron Paramagnetic Resonance in Electron-Irradiated p-Type GaN. L.S.Vlasenko, C.Bozdog, G.D.Watkins, F.Shahedipour, B.W.Wessels: Physical Review B, 2002, 65[20], 205202 (4pp)