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 5x1015 cm-2, while are kept at different temperatures during the implantation, i.e. room temperature, 300 and 500 oC, respectively. After an annealing step at 850 oC 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 oC implanted p-GaN film ferromagnetism is found with obvious hysteresis loop. Further increase in the implantation temperature to 500 oC 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