Annealing of GaN-InGaN multi quantum wells: Correlation between the bandgap and yellow photoluminescence

We report experimental data on photoluminescence (PL) annealing of metalorganic chemical vapor deposition (MOCVD) grown GaN-InGaN multi quantum wells (MQWs). The formation of phase separation in the InGaN quantum well layer was confirmed by PL mapping when the MQW was grown at 675 degrees C. Spatial distribution of the yellow (Y)-band PL correlated with the dislocation network in that the intensity of the PL was lowest at the grain boundaries. The activation energy of thermal quenching of the InGaN PL at 400 nm was found to be equal to that of the increase of Y-band PL at 550 nm. The origin of the Y-band is explained as a radiative donor-acceptor recombination.