Resonant exciton-phonon coupling in ZnO nanorods at room temperature

Vibronic and optoelectronic properties, along with detailed studies of exciton-phonon coupling at room temperature (RT) for random and aligned ZnO nanorods are reported. Excitation energy dependent Raman studies are performed for detailed analysis of multi-phonon processes in the nanorods. We report here the origin of coupling between free exciton and its associated phonon replicas, including its higher order modes, in the photoluminescence spectra at RT. Resonance of excitonic electron and resonating first order zone center LO phonon, invoked strongly by Frolich interaction, are made responsible for the observed phenomenon.