Deep-level transient spectroscopy was used to characterise four defects with shallow levels in specimens grown via pulsed laser deposition. These defects all had deep-level transient spectroscopic peaks below 100K From deep-level transient spectroscopic measurements and Arrhenius plots, the energy levels of the defects were calculated to be 31, 64, 100 and 140meV, respectively, below the conduction band. The 100meV defect exhibited metastable behaviour. Annealing under reverse bias at above 130K introduced it, while annealing under zero bias above 110K removed it. The 64 and 140meV defects exhibited a strong electric field assisted emission; indicating that they may be donors.

Electronic Properties of Shallow Level Defects in ZnO Grown by Pulsed Laser Deposition. Auret, F.D., Meyer, W.E., Van Rensburg, P.J.J., Hayes, M., Nel, J.M., Von Wenckstern, H., Hochmuth, H., Biehne, G., Lorenz, M., Grundmann, M.: Journal of Physics - Conference Series, 2008, 100[4], 042038