Point defects were created by various types of irradiation: electrons (1 and 2.5MeV, spectrum from 90Sr), protons (0.15MeV, 2MeV and 24GeV), He ions (5.4MeV), γ-rays (60Co) and the sputtering and e-beam deposition of metals. They were studied by means of temperature-dependent Hall-effect measurements, deep-level transient spectroscopy, optically detected magnetic resonance, positron annihilation spectroscopy and photoluminescence. The definite or tentative defect energies were: Hall-effect measurements (donor at 0.06eV, VN), deep-level transient spectroscopy (electron trap at 0.18eV (thermal 0.06eV), VN, electron trap at 0.9eV, NI or GaI-X), optically detected magnetic resonance (GaI and GaI-X), positron annihilation spectroscopy (VGa), photoluminescence (0.85eV band with 0.88eV zero-phonon line, ON or ON-GaI, 0.93eV band; 3.37eV line; 3.39eV line). Many of these defect signatures had also been observed in as-grown GaN. Dislocations of threading-edge type were found to be acceptor-like in n-type GaN.

Defect-Related Donors, Acceptors and Traps in GaN. D.C.Look: Physica Status Solidi B, 2001, 228[1], 293-302