Three broad overlapping photoluminescence bands, centered at about 1.75eV (red), 2.2eV (yellow) and 2.33eV (green), were observed in low dislocation-content GaN grown by means of hydride vapor-phase epitaxy. Optical detection of electron paramagnetic resonance studies revealed that each was fed by spin-dependent electron transfer from a shallow donor to a deeper defect which was different for each of the bands and different from the defects previously found in GaN grown by using more conventional epitaxy methods (metalorganic vapor-phase epitaxy, molecular-beam epitaxy). The g-values for the deeper defects suggested a 2-stage luminescence process in which the luminescence

arose from hole capture at the specific defect in each case, after the spin-dependent electron capture observed using the optical detection of electron paramagnetic resonance. This model also fitted the deep level usually found in the yellow band of more heavily dislocated materials. An additional weak anisotropic optically detected electron paramagnetic resonance signal was also observed in the red and yellow bands. None of the signals exhibited resolved hyperfine interactions, and their chemical and/or lattice structures remained unknown.

Optical Detection of Electron Paramagnetic Resonance in Low-Dislocation-Content GaN Grown by Hydride Vapor-Phase Epitaxy. C.Bozdog, G.D.Watkins, H.Sunakawa, N.Kuroda, A.Usui: Physical Review B, 2002, 65[12], 125207 (6pp)