Electronic properties of vacancy related defects in ZnO induced by mechanical polishing

Electronic properties of defects induced by mechanical polishing in hydrothermally grown n-type ZnO have been investigated by capacitance versus voltage measurements and deep level transient spectroscopy (DLTS). The DLTS measurements have been performed in the temperature range 80-600 K enabling exploration of deep-level states in the vicinity of the middle of the energy bandgap. 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 are revealed with energy level positions around 1.0 eV and 1.2 eV below the conduction band edge. These levels are assigned to vacancy-related defect centers and substantially reduced in strength by post-polishing etching in diluted hydrofluoric acid. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3638470]