Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Poster 2

HL 46.37: Poster

Donnerstag, 29. März 2007, 15:00–17:30, Poster A

Measurements of the absolute external luminescence quantum efficiency of ZnO — •Mario Hauser, Alexander Hepting, Robert Hauschild, Felix Stelzl, Johannes Fallert, Markus Wissinger, Huijuan Zhou, Heinz Kalt, and Claus Klingshirn — Universität Karlsruhe (TH), Karlsruhe, Germany

The prospects of ZnO in light emitting devices such as high power blue and UV laser diodes depend crucially on the luminescence quantum efficiency.

The absolute external luminescence quantum efficiency is measured using a temperature controlled integrating sphere (Ulbricht sphere). Temperature dependant and spectrally resolved measurements are carried out from 10 K up to room temperature on commercially available ZnO nanocrystalline powders and laboratory bulk samples. At low temperatures the former show a typical quantum efficiency of 8 to 10 %. The quantum efficiency of the latter varies from 5 to 20 %. Over the considered temperature range a decrease of quantum efficiency of about one order of magnitude depending on sample quality can be observed. A fit to the temperature dependant quantum efficiency of the near band edge emission shows that there is an activated process with an activation energy on the order of 10 meV in all samples. The spectral evolution with temperature of deep defect and near band edge luminescence is discussed.