Temperature dependence of photoluminescence in Mg-doped GaN epilayers grown by MOCVD

High quality magnesium doped GaN epitaxial layers on sapphire substrate were achieved by the rotating disk MOCVD. Energy levels of these accepters were investigated by temperature dependent photoluminescence measurements. Magnesium concentration was varied from < 1 x 10(19) to higher than 5 x 10(19) cm(-3). In the samples with lower magnesium concentration we have observed free excitonic transitions and the donor-acceptor pair transition with its phonon replicas. For the samples with higher magnesium concentration the spectra were dominated by acceptor related transitions. In this study, we could not see any deep level luminescence even in highly Mg-doped GaN and free excitonic transitions were observed in doped materials. These facts show the high quality of samples.