Temperature dependent photoluminescence of MBE grown gallium nitride quantum dots

We report on the growth and optical properties of gallium nitride quantum d ots (QDs) grown by plasma-assisted molecular beam epitaxy. We have observed strong photoluminescence (PL) from the QDs from 8 to 750 K. Atomic force m icroscopy studies demonstrate that the QDs have diameters of (30 +/- 5) nm and heights of (3 +/- 1) nm. PL from the quantum dots was compared to that of a gallium nitride growth template film to unambiguously demonstrate the contribution of the QDs to the spectra. Integrated PL intensity was observe d to remain strong well above 300 K, and we attribute the decrease in the q uantum dot PL at higher temperatures to phonon-mediated carrier ionization of deep level.