Annealing behavior of luminescence from erbium-implanted GaN films

We have conducted a systematic study of the bandedge and infrared luminescence properties of Er-implanted GaN thin films. The GaN films, grown by metalorganic chemical vapor deposition, were co-implanted with Er and O ions. After implantation, the implanted samples were furnace annealed at temperatures up to 1100°C. Following annealing, the samples were examined for both bandedge luminescence and for infrared luminescence near 1540 nm. It was observed that the bandedge photoluminescence (PL) was significantly reduced in the as-implanted samples. In addition, there was no detectable PL signal near 1540 nm, with either above-bandgap or below-bandgap excitation. Only after annealing at temperatures above 900°C did both the bandedge luminescence and the 1540 nm luminescence become well defined. An optical transition at 3.28 eV was also observed, apparently induced through Er+O implantation. While annealing at higher temperatures resulted in a decrease in the 1540 nm luminescence, emission intensities from the bandedge and the defect level both increased.