Point defects were created by electrons (1 or 2.5MeV, and the spectrum from 90Sr), protons (0.15MeV, 2MeV or 24GeV), He ions (5.4MeV), γ-rays (60Co) and the sputtering and electron-beam deposition of metals. They were studied by means of the temperature-dependent Hall-effect, deep-level transient spectroscopy, optically detected magnetic resonance, positron annihilation spectroscopy and photoluminescence. The corresponding defect energies and attributions were deduced to be: donor at 0.06eV, VN (temperature-dependent Hall-effect), electron trap at 0.18eV, VN, electron trap at 0.9eV, NI or GaI-X (deep-level transient spectroscopy), GaI and GaI-X (optically detected magnetic resonance), VGa (positron annihilation spectroscopy), 0.85eV band with 0.88eV zero-phonon line, ON or ON-GaI, 0.93eV band, 3.37eV line, 3.39eV line (photoluminescence). 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