We report on the measurement of the absolute external luminescence quantum efficiency that is directly accessible using a miniature integrating sphere fitted into a cryostat. Various measurements have been carried out on high quality laboratory bulk samples and different commercially available ZnO powders from 10 K up to room temperature. A fit to the temperature dependent quantum efficiency shows the existence of various activated processes.
M. Hauser, A. Hepting, R. Hauschild, M. Wissinger, H. Zhou, F. Stelzl, J. Fallert, H. Kalt, C. Klingshirn
Journal of the Korean Physical Society 53(5), 2826-2829 (2008)