The influence of annealing ambient on properties of Er-implanted GaN films

GaN crystalline films were grown on SiC and Si substrates by molecular beam epitaxy. Er doping was carried out by ion implantation at an energy of 180 keV with fluences from 5 × 10 13 to 5 × 10 15 ions cm −2 . The as-implanted samples were then annealed at 650°C, 800°C, 950°C and 1100°C, respectively. The annealing at temperatures as high as 1100°C did not exert any influence on implant-induced lattice damage. After annealing all the samples gave a PL signal at 1.54 µm. The most intensive PL emission came from the sample annealed at 950°C. Annealing at 1100°C resulted in the diffusion of Er ions and ion aggregation near the film surface, which degraded the photoluminescence from Er ions significantly. After annealing at temperatures higher than 800°C, an oxide layer was formed on the surface of GaN and high temperature annealing at 1100°C results in both a rough film surface and nonuniform distribution of ions, which has been investigated by transmission electron microscope.