Identification of bound exciton complexes in ZnO

An identification of shallow bound exciton centers in ZnO is presented based on magneto-optical measurements and diffusion experiments. The thermalization behavior of the Zeeman split components confirms that the I-4, I-6, I-8 and I-9 exciton lines stem from donor bound exciton complexes. The results are supported by theoretical analysis of shallow bound exciton complexes revealing the Gamma(7) symmetry of the upper valence band. The presence of two-electron satellites related to the respective transitions is further evidence for the donor bound complexes and enabled the determination of donor binding energies. Hydrogen, aluminum, gallium and indium were identified to origin the I-4, I-6, I-8 and I-9 lines by doping, diffusion and annealing experiments combined with photolummescence and secondary ion mass spectrometry. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.