On the origin of the yellow donor-acceptor pair emission in GaN

The "deep" yellow donor-acceptor pair (DAP) recombination is perhaps the most known but less understood photoluminescence (PL) emission of GaN. The origin of the "yellow" DAP emission was recently discussed based on the results of optically detected magnetic resonance (ODMR), stress and PL kinetics investigations. A deep donor-shallow acceptor transition was proposed based on the results of one ODMR study, whereas other ODMR experiments and stress and PL kinetics measurements were explained in terms of a shallow donor-deep acceptor transition model. The present FL investigations support the second model of the "yellow" DAP emission. However, the presence of an underlying second PL emission may explain the reasons for conflicting explanations of the results of the ODMR investigations by two different groups.