Electrical isolation of GaN by MeV ion irradiation

The evolution of sheet resistance of n-type GaN epilayers exposed to irradi ation with MeV H, Li, C, and O ions is studied in situ. Results show that t he 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 iso lation is stable to rapid thermal annealing at temperatures up to 900 degre esC. In addition to providing a better understanding of the physical mechan isms responsible for electrical isolation, these results can be used for ch oosing implant conditions necessary for an effective electrical isolation o f GaN-based devices. (C) 2001 American Institute of Physics.