The Mg-doping effect on the photoluminescence and the photocurrent spectra was investigated for various p-GaN thin films. At a low-concentration Mg-doping level, there exists the photoluminescence center on a donor and acceptor pair transition of a 3.28 eV band. This center correlates with the defect structures for a shallow donor of VGa and for an acceptor MgGa. The acceptor level showed a binding energy of 0.11-0.4 eV, which was observed at the PC center of 3.02-3.31 eV.
