Detailed investigation of photoluminescence, structural, and elemental properties of ZnO thin films under various annealing ambient

Zinc oxide (ZnO) has extensively exploited the material in the field of optoelectronics due to its inherent wide bandgap and high electron mobility. Properties of ZnO is very sensitive to its deposition methods and conditions. We report the effect of annealing ambient (i.e. argon, nitrogen, oxygen, or vacuum) on the optical, structural and elemental properties of the RF-sputtered ZnO thin films. In this work, we have performed compressive study on the effects of annealing ambient on a donor-bound exciton peak, exciton-exciton and electron-exciton scattering using low temperature (18 K) photoluminescence measurement which is not yet well understood. We have reported dominant on the donor-bound exciton peak with the lowest full width half maximum value (similar to 4.48 nm) for annealing in an oxygen ambient. The annealing ambient strongly influenced the elemental properties of the film and we have reported the reduction in oxygen vacancy with annealing in an oxygen ambient. This work showed that the influence of ex-situ annealing ambient on exciton emission of ZnO thin films and thus providing a tool for enhancing the optical and elemental properties of the film.