Activation of beryllium-implanted gallium nitride by combined pulse laser and rapid thermal annealing

Investigations of post-implantation annealing were carried out on gallium nitride wafers that had been implanted with beryllium ions. The thermal processes performed were rapid thermal annealing (RTA) at 1100°C for 120 s, pulse laser annealing (PLA) using a 248 nm KrF excimer laser at an energy of 0.2 Jcm^-2 and a combination of both. It was found that the photoluminescence intensity of the PLA-treated sample was vastly improved over the RTA sample and even the as grown sample. However, off-resonance Raman and high resolution X-ray diffraction spectroscopy showed that many defects that result from the Be implantation still remained in the GaN wafer, because of the shallow penetration depth of the 248 nm laser. These defects can be annealed out, however, with a subsequent RTA process. Thus, a combination of PLA and RTA is recommended to produce good optical activation of the Be-implanted GaN, and to repair the crystal defects that arise from the implantation.