Exciton–phonon coupling and exciton thermalization in MgxZn1−xO thin films

Temperature dependent transmission measurements have been performed on MgxZn1−xO thin layers on sapphire with x in the range from 0 to 0.33. Multiple minima can be observed in the spectra from samples with low Mg content. These can be attributed to exciton–phonon complexes. To determine the exciton transition energy, the transmission spectra have been fitted using the model dielectric function of Adachi with Gaussian-like broadening. The exciton transition energy is compared to the photoluminescence maximum in dependence on temperature and Mg content.