A photoluminescence and photo-current study was made of Mg-doped p-type GaN grown onto sapphire substrate by means of metalorganic chemical vapor deposition. In the photoluminescence spectra, either a strong blue emission at 2.88eV or weak band-edge related photoluminescence peaks were observed at room temperature; depending upon the initial annealing conditions. The photo-current spectra exhibited a principal band which was located at 3.01eV, and an additional band around 1.22eV which also depended upon the annealing conditions. The photoluminescence and photo-current results suggested that the photo-current peak at 1.22eV was associated with absorption from the valence band edge to the deep donor state located above the Mg acceptor level.

Photoluminescence and Photocurrent Studies of p-Type GaN with Various Thermal Treatments. S.J.Chung, E.K.Suh, H.J.Lee, H.B.Mao, S.J.Park: Journal of Crystal Growth, 2002, 235[1-4], 49-54