Transient capacitance measurements of Schottky diodes fabricated on nominally undoped n-type GaN exposed to 60Co γ-irradiation revealed the introduction of 2 defect levels with thermal activation energies of 0.089 and 0.132eV. While the emission characteristics of these defects exhibited significant broadening, 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, which were present before irradiation, were found to remain unaffected at 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