Positron annihilation spectra revealed isolated zinc vacancy (VZn) creation in single-crystal ZnO exposed to 193nm radiation at 100mJ/cm2 fluence. The appearance of a photoluminescence excitation peak at 3.18eV in irradiated ZnO was attributed to an electronic transition from the VZn acceptor level at ∼100meV to the conduction band. The observed VZn density profile and hyperthermal Zn+ ion emission support zinc vacancy-interstitial Frenkel pair creation by exciting a wide 6.34eV Zn-O antibonding state at 193nm photon - a novel photo-electronic process for controlled VZn creation in ZnO.

Formation of Isolated Zn Vacancies in ZnO Single Crystals by Absorption of Ultraviolet Radiation: a Combined Study using Positron Annihilation, Photoluminescence, and Mass Spectroscopy. Khan, E.H., Weber, M.H., McCluskey, M.D.: Physical Review Letters, 2013, 111[1], 017401