Heavy ion implantation in GaN epilayers

Abstract

GaN epilayers grown on sapphire were implanted with several fluences of In, Er and Hf ions to study the damage behavior and lattice site location of the implanted species. The damage in the Ga sublattice develops a double peak structure with one peak at the surface and the other near the end of the range of the implanted ions. For fluences above 5 × 1015 Er+ /cm2 the peaks overlap and the implanted region becomes amorphous. Rapid thermal annealing at 600×C recovers completely the damage produced by the implantation of 5 × 1014 In+ /cm2 while only a small recovery was observed for samples implanted with similar Er and Hf fluences. Defect recovery studies with hyperfine interaction techniques using 111In and 181Hf as probes show that below 600°C only defects in the N sublattice anneal out whereas temperatures up to 1000°C are necessary to restore the short range order to the Ga sublattice. Similarly the RBS measurements showed that rapid thermal annealing up to 1000°C was not enough to recover completely the crystallinity of the samples.