Optical properties of Mg-implanted GaN

Room-temperature photoluminescence spectra of Mg-implanted GaN grown on sapphire by low-pressure metal-organic chemical vapor deposition have been studied. An obvious blue emission and a broad yellow-band emission were observed. Spectra analysis suggests that, in the forbidden band of GaN, there exist four doping-related energy levels at 170 meV and 310 meV below the conduction band, and at 250 meV and 390 meV above the valence band, respectively. Transitions between these energy levels give the blue emission of 415 nm and 438 nm. Also, annealing partially recovers the GaN crystalline structure, leading to the reappearance of the yellow-band luminescence.