Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.38: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Cathodoluminescence of PLD grown ZnO thin films: A comparison of experiment and simulation — •Robert Johne, Michael Lorenz, Holger Hochmuth, Jörg Lenzner, Holger von Wenckstern, Gabriele Benndorf, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, 04103 Leipzig, Germany

We have investigated ZnO thin films on sapphire, which are intended to serve as scintillators. Cathodoluminescence (CL) spectra were excited on the ZnO side of the thin film samples and the emitted light was detected in two geometries: (a) on the ZnO side (reflection geometry) and (b) on the sapphire substrate side (transmission geometry). The excitonic CL peak in reflection geometry red-shifts with increasing CL excitation energy. This redshift and the peak shift of reflection relative to transmission geometry spectra can be explained by a model of photon propagation including the effect of self-absorption of the near band edge luminescence in the ZnO film. In addition, different surface morphologies, slopes and positions of the intrinsic absorption edge and effects to due detection in a limited solid angle were included in the simulation and compared with experimental results. These influences may explain the occasionally observed double peak structure of experimental CL spectra in reflection geometry.