Rapid thermal annealing induced change of the mechanism of multiphonon resonant Raman scattering from ZnO nanorods

Multiphonon Resonant Raman scattering (RRS) excited by 351.1 and 363.8 nm lines of an Ar+ laser was studied at temperatures from 10 to 300 K in as-grown and rapid thermal annealed (RTA) aluminum doped ZnO nanorods synthesized by an aqueous chemical deposition method using zinc sulfate, aluminum sulfate, and ammonia hydroxide as precursors. RTA of ZnO nanorods at temperatures 650–750∘C was found to result in changing the mechanism of RRS from incoming to outgoing. This change is suggested to be related to the RTA induced improvement of the optical properties of the nanorods.