Temperature Dependent Excitonic Photoluminescence from Epitaxial ZnO Thin Films
نویسندگان
چکیده
We have studied the photoluminescence of highly transparent and c-axis oriented ZnO thin films grown on (0001) sapphire by Pulsed Laser Deposition at different temperatures ranging from 10K to 300K. We observed temperature dependent recombination from free excitons, bound excitons and LO phonon assisted free and bound excitonic transitions. The energies of free excitonic transitions are close to that of the bulk values of ZnO. Varsani’s coefficient for band gap variation with temperature was found to fit with that of ZnO as obtained from the PL spectra. Variation of line width of the free excitonic transitions was studied as a function of temperature and a theoretical model was found to explain the temperature dependent broadening in terms of exciton-Phonon scattering.
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