Electrical and optical properties of p-GaN films implanted with transition metal impurities

摘要

The electrical and optical properties and the spectra of deep hole traps in p-GaN films implanted with Co, Mn, Fe and Cr and annealed at 700℃ were studied. The amount of increase in the series resistance of TM implanted and annealed p-GaN films can be reduced for samples with higher Mg doping and higher Mg acceptor activation efficiency. This is of primary importance for practical use in fabricating GaN spin-LEDs by TM ion implantation into the top p-GaN layer of a spin-LED structure involving injection from GaMnN into a InGaN MQW structure. The Fermi level after the implantation of these TM elements into p-GaN is found not to be shifted far away from the Mg acceptors band where it is pinned in the virgin samples. The main deep defects generated by implantation are found to be the 0.3eV hole traps and the 0.9 eV hole traps as in the case of p-GaN samples heavily implanted with protons.In practical terms it is found that for fabricating GaN-based spin-LEDs by implantation of TM ions the best results should be expected for the Cr implantation which has also been shown to produce the highest Curie temperature ( > 350 K in p-GaN,by both implantation or MBE growth).