Annealing study of ion implanted GaN

Ca is a potential shallow acceptor in GaN and was used for p-type doping in this study. Ca+ implantation with an energy of 180 keV was carried out in a dose range between 5×1013 and 7.3×1016 cm−2 at room temperature. After implantation, rapid thermal annealing at 950–1150°C for 15–60 s in flowing N2 was performed to remove damage and to activate the dopants. The implantation-induced damage, the surface morphology and stoichiometry of the implanted film before and after annealing were studied by Rutherford backscattering/channeling, atomic force microscopy and Auger electron spectroscopy, respectively. The dependence of the damage build-up and removal on ion dose and annealing temperature was quantitatively analyzed. The duration of 30 s at 1150°C has been shown to be the best annealing time. Surface degeneration of the implanted GaN after rapid thermal annealing at 1150°C for 15–60 s was observed.