Transient capacitance measurements of Schottky diodes, fabricated on nominally undoped n-type GaN and exposed to 60Co γ-irradiation, indicated the introduction of 2 defect levels with thermal activation energies of 0.089 and 0.132eV. The emission characteristics of these defects exhibited significant broadening, and their parameters were consistent with reported electron irradiation-induced N-vacancy related centers. Three deep-level defects with activation energies of 0.265, 0.355 and 0.581eV, present before irradiation exposure, were found to remain unaffected for cumulative γ-ray doses of up to 21Mrad(Si).

60Co Gamma Irradiation-Induced Defects in n-GaN. G.A.Umana-Membreno, J.M.Dell, T.P.Hessler, B.D.Nener, G.Parish, L.Faraone, U.K.Mishra: Applied Physics Letters, 2002, 80[23], 4354-6