Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 38: ZnO and Related Semiconductors
HL 38.9: Vortrag
Mittwoch, 24. März 2010, 11:45–12:00, H17
Excitons and their excitation channels in a-plane and c-plane ZnO — •Martin Kaiser1, Markus R. Wagner1, Gordon Callsen1, Axel Hoffmann1, S. Lautenschläger2, S. Eisermann2, and Bruno K. Meyer2 — 1Institut für Festkörperphysik, Technische Universität Berlin Germany — 2Physikalisches Institut , Justus-Liebig-Universität Gießen, Germany
In the last decade ZnO inspired an experimental revival due to improvements in growth techniques and its potential for future devices like polariton lasers and spintronic materials. However, the growth of high quality ZnO and p-doping is still a big challenge. Optical characterizations of defects and excitons assist in the understanding of energy transfer processes and provide indications for the optimization of the growth parameters. We report on studies for a-plane and c-plane grown bulk ZnO. Compared to non-polar a-plane material [1120], ZnO has a strong piezoelectric field for polar growth along the c-direction [0001]. In this contribution, we present polarization dependent photoluminescence (PL) spectra in order to study the influence of the polarity on the radiative free and bound exciton recombinations. Through photoluminescence excitation (PLE) measurements excitation channels of the various bound excitons are obtained. In addition, the excitation channels for the free A-excitions are studied. These results yield new insight into the energy transfer processes. Finally, we present infrared (IR) transmission data indicating the presence of deep impurities which may trap carriers and also affect the bandgap luminescence.