Ion implantation induced defects in ZnO

N-type ZnO single crystals have been implanted with 500 keV O+ and 1.2 MeV Zn+ ions using doses between 1×10111×1011 and 2×1012cm−2, and the generation of deep-level defects in the upper part of the band gap has been studied by capacitance–voltage (CV) and deep level transient spectroscopy (DLTS) performed up to sample temperatures of 500 K. At least three implantation-related deep defects are observed by DLTS, with activation energies of 0.57, 0.97 and 1.2 eV below the conduction band edge. The generation of the two latter levels is pronounced in the reported samples, while the former has lower generation rate for O and Zn implantations compared to electrons and light ion irradiation. Moreover, a dramatic change in the depth distribution of charge carriers is observed, indicating acceptor generation or donor migration at or below 400 K.