Pressurized melt grown zinc oxide single crystals were irradiated with 2MeV electrons to a fluence of 6 x 1017/cm2. Isochronal annealing from 100 to 800C was performed on the crystals under argon and air ambients. Variable-energy Doppler-broadening spectroscopy was carried out on both the as-grown and the irradiated samples at each annealing step. The migration, agglomeration and annealing of grown-in and irradiated-introduced defects were studied. It was observed that the grown-in vacancy-type defects concentration decreased at 300 and 600C. For the irradiated sample annealed in argon, the positron trapping vacancy-type defect concentration decreased at 300 and 600C. Further annealing the as-grown and irradiated samples in argon increased the S parameter further. For the irradiated sample annealed in air, the vacancy-type defect concentration decreases at 300 and 700C.

Positron Annihilation Study of Defects in Electron-Irradiated Single Crystal Zinc Oxide. C.K.To, B.Yang, C.D.Beling, S.Fung, C.C.Ling, M.Gong: Journal of Physics - Conference Series, 2011, 262[1], 012059