The influence of implantation temperature on the magnetism and structure of Mn+ implanted p-GaN films

Wurtzite p-type GaN epilayer, which has a thickness of 0.5 μm, is prepared by MOCVD on GaN buffer with sapphire substrate. Magnetic doping of the p-type GaN epilayer is achieved by 180 keV Mn+ ions implantation. The GaN films are all implanted with dose of 5×1015 cm−2, while are kept at different temperatures during the implantation, i.e. room temperature, 300 and 500 °C, respectively. After an annealing step at 850 °C for 30 s in flowing N2, the magnetism of the Mn+-implanted p-GaN films is investigated by superconducting quantum interference device (SQUID). In the sample implanted at room temperature the magnetism is weak and no ferromagnetism is found. In the 300 °C implanted p-GaN film ferromagnetism is found with obvious hysteresis loop. Further increase in the implantation temperature to 500 °C brings about no increase in ferromagnetism. Combined with the structural characteristics of the Mn+-implanted p-GaN films studied by X-ray diffraction (XRD), one concludes that only suitable increase of the implantation temperature could be beneficial to the recovery of implantation defects and the generation of ferromagnetism in the Mn+-implanted p-GaN films.