Electrical isolation of GaN by MeV ion irradiation

The evolution of sheet resistance of n-type GaN epilayers exposed to irradiation with MeV H, Li, C, and O ions is studied in situ. Results show that the threshold dose necessary for complete isolation linearly depends on the original free electron concentration and reciprocally depends on the number of atomic displacements produced by ion irradiation. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 degreesC. In addition to providing a better understanding of the physical mechanisms responsible for electrical isolation, these results can be used for choosing implant conditions necessary for an effective electrical isolation of GaN-based devices. (C) 2001 American Institute of Physics.