Electronic properties of defects induced by mechanical polishing in hydrothermally grown n-type ZnO were investigated by capacitance versus voltage measurements and deep level transient spectroscopy. The latter measurements were performed at 80 to 600K, permitting exploration of deep-level states in the vicinity of the middle of the energy band-gap. The results showed that mechanical polishing formed defects in the near-surface region which strongly compensated and/or passivated the dominant shallow donors. Two pronounced polishing-induced defects were revealed with energy level positions around 1.0 and 1.2eV below the conduction band edge. These levels were assigned to vacancy-related defect centers and substantially reduced in strength by post-polishing etching in diluted hydrofluoric acid.

Electronic Properties of Vacancy Related Defects in ZnO Induced by Mechanical Polishing. Quemener, V., Vines, L., Monakhov, E.V., Svensson, B.G.: Applied Physics Letters, 2011, 99[11], 112112