Photoluminescence spectra in the band-edge emission region of very high quality undoped ZnO were studied as a function of sample growth methods and conditions, and the measurement temperature. As a result, the defect types responsible for emission peaks observed in the band-edge emission region could be classified into 3 groups. In addition, the lattice defects which were probably responsible for the emission peaks were suggested to be O vacancies and/or interstitial Zn, or residual Al impurities.

Characterization of ZnO Crystals by Photoluminescence Spectroscopy. H.Shibata, M.Watanabe, M.Sakai, K.Oka, P.Fons, K.Iwata, A.Yamada, K.Matsubara, K.Sakurai, H.Tampo, K.Nakahara, S.Niki: Physica Status Solidi C, 2004, 1[4], 872-5