Defects in as-grown commercial ZnO substrates were studied by photoluminescence and optically detected magnetic resonance. In addition to the Zn vacancy and shallow donor centers, several optically detected magnetic resonance centers were observed with spin, S = 1/2; labelled LU1 to LU4. Among these, the axial LU3 and non-axial LU4 centers were detected in all studied samples. The optically detected magnetic resonance signals of LU3/LU4 were found to be drastically increased after electron irradiation. The preliminary result indicated that these common optically detected magnetic resonance centers in as-grown ZnO were related to intrinsic defects.

Common Point Defects in As-Grown ZnO Substrates Studied by Optical Detection of Magnetic Resonance. Son, N.T., Ivanov, I.G., Kuznetsov, A., Svensson, B.G., Zhao, Q.X., Willander, M., Morishita, M.N., Ohshima, T., Itoh, H., Isoya, J., Janzén, E., Yakimova, R.: Journal of Crystal Growth, 2008, 310[5], 1006-9