Intrinsic defects produced in ZnO by 2.5-MeV electron irradiation in situ at 4.2 K are studied by optical detection of electron paramagnetic resonance (ODEPR). Observed in the photoluminescence (PL) are ODEPR signals, which are identified with the oxygen vacancy, ${\mathrm{V}}_{\mathrm{O}}^{+}$, interstitial zinc, ${\mathrm{Zn}}_i^{+}$, and zinc-vacancy–zinc-interstitial Frenkel pairs. The Frenkel pairs are primarily observed in their $S=1$ exchange-coupled state, supplying strong evidence that interstitial zinc is a shallow effective mass double donor in ZnO. Annealing stages at $\sim 65\text{–}119\mathrm{K}$ and $\sim 145\text{–}170\mathrm{K}$ are observed for the defects associated with the zinc sublattice and are identified with the migration of interstitial zinc. Although interstitial oxygen is not observed in the ODEPR, a higher-temperature annealing stage observed in the PL at $\sim 160\text{–}230\mathrm{K}$ is tentatively identified with the onset of its migration. The oxygen vacancy is stable to $\sim 400°\mathrm{C}$. The relationship between the spin-dependent processes producing the ODEPR signals and the PL of the material remains unclear.

• Received 14 February 2005

DOI:https://doi.org/10.1103/PhysRevB.72.035203