60Co gamma-irradiation-induced defects in n-GaN

Transient capacitance measurements of Schottky diodes fabricated on nominally undoped n-type GaN exposed to Co-60 gamma irradiation indicate the introduction of two defect levels with thermal activation energies of 89+/-6 and 132+/-11 meV. While the emission characteristics of these defects manifest significant broadening, their parameters are consistent with reported electron-irradiation-induced nitrogen-vacancy related centers. Three deep-level defects present before irradiation exposure with activation energies of 265, 355, and 581 meV were found to remain unaffected for cumulative gamma-ray doses up to 21 Mrad(Si). (C) 2002 American Institute of Physics.