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 (DLTS). The DLTS measurements were performed in the temperature range 80-600K enabling exploration of deep-level states in the vicinity of the middle of the energy band-gap. The results show that mechanical polishing forms defects in the near surface region which strongly compensate and/or passivate 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. V.Quemener, L.Vines, E.V.Monakhov, B.G.Svensson: Applied Physics Letters, 2011, 99[11], 112112