Deep acceptor states in ZnO single crystals

The authors report the observation of both acceptor- and donorlike defects in ZnO by deep level transient spectroscopy. The observation is facilitated by using a p-n junction allowing the injection of holes and electrons. The junction is realized by implanting a n-conducting ZnO wafer grown by pressurized melt growth with nitrogen ions. The authors found the commonly observed donorlike defects E1 and E3 and two acceptorlike defects A2 and A3, as well as a broad acceptorlike defect band. The thermal activation energies of A2 and A3, were determined to be about 150 and 280 meV, respectively.