Intrinsic defects produced in ZnO by 2.5MeV electron irradiation in situ at 4.2K were studied by optical detection of electron paramagnetic resonance (ODEPR). Observed in the photoluminescence were ODEPR signals, which were identified with the O vacancy, VO+, interstitial Zn, Zni+, and Zn-vacancy–Zn-interstitial Frenkel pairs. The Frenkel pairs were primarily observed in their S = 1 exchange-coupled state, supplying strong evidence that interstitial Zn was a shallow effective mass double donor in ZnO. Annealing stages at 65 to 119K and 145 to 170K were observed for the defects associated with the zinc sub-lattice and were identified with the migration of interstitial Zn. Although interstitial O was not observed in the ODEPR, a higher-temperature annealing stage observed in the photoluminescence at 160 to 230K was tentatively identified with the onset of its migration. The O vacancy was stable to about 400C. The relationship between the spin-dependent processes producing the ODEPR signals and the photoluminescence of the material remained unclear.

Optical Detection of Electron Paramagnetic Resonance for Intrinsic Defects Produced in ZnO by 2.5MeV Electron Irradiation in situ at 4.2K. L.S.Vlasenko, G.D.Watkins: Physical Review B, 2005, 72[3], 035203 (12pp)