Time-resolved ODMR measurements on the ''yellow luminescence'' in MOCVD-grown GaN films

Time-resolved photoluminescence (PL) and time-resolved optically detected magnetic resonance (ODMR) measurements were performed on the 2.2 eV luminescence in GaN films grown with MOCVD. This yellow luminescence can be excited with light above or below band gap. The ODMR detected via this luminescence shows two dominant resonances already known which were associated to a shallow and a deep level donor. Both resonances can also be measured with excitation below band gap (3.2 eV). In addition a broad and weak resonance was found underneath these two dominating signals. Time resolved PL and time-resolved ODMR measurements were performed for excitation with photon energies above and below band gap. The decay behavior of the PL and of the ODMR after switching off the excitation light or the microwaves, respectively, depends on the photon energy of the excitation light.