Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: ZnO: preparation and characterization II

HL 36.4: Talk

Wednesday, March 25, 2009, 14:45–15:00, POT 51

Excitonic Recombination in MgZnO thin films — •Alexander Müller, Marko Stölzel, Gabriele Benndorf, Holger Hochmuth, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany

We present time-resolved photoluminescence (TRPL) measurements on MgZnO thin films. The samples have been grown by pulsed laser deposition on a-plane sapphire. We used time-correlated single photon counting to investigate the luminescence decay. The measured transients have been fitted using the convolution of a model decay function with the device function.

Due to random fluctuations of the local potential, the photoluminescence (PL) emission of MgZnO shows a large mixed crystal broadening. In contrast to pure ZnO, for Mg contents of more than 3 % in the thin films it is not possible to spectrally resolve the luminescence bands using standard PL. Therefore, the origin of the luminescence is not well known.

In this contribution, we present the spectral and temperature dependence of the TRPL transients. For low temperatures, we observe a blue shift of the spectral luminescence maximum over time. This can be explained by a slow process at higher emission energies.

The transients could be fitted using a sum of two model decay functions. The time-integrated intensities of the model decays show different spectral maxima. We attribute these to the emission of donor-bound and free excitons.