An investigation was made of a defect-related luminescence which was centered around 2.8eV in Si-doped GaN epitaxial films. It was found that the mechanism of this blue emission was quite different to that of the yellow luminescence. After comparing the photoluminescence spectra which were obtained from front-side or reverse-side excitation, and combining them with the results of the blue luminescence and yellow luminescence-related photoluminescence excitation and secondary ion mass spectroscopic measurements, it was proposed that the 2.8eV emission was due to a transition from the substitutional O donor (ON) level, at 0.25eV above the conduction band, to the VGa-ON complex acceptor. The energy level of the VGa-ON complex was found to lie at 0.8eV above the valence-band edge. This was consistent with theoretical calculations. It was shown that the VGa defect played a key role in linking the temporal evolution of the yellow luminescence and blue luminescence spectra.

Nature of the 2.8eV Photoluminescence Band in Si-Doped GaN. H.C.Yang, T.Y.Lin, Y.F.Chen: Physical Review B, 2000, 62[19], 12593-6