Influence of annealing atmosphere on optical properties of Al-doped ZnO powders

We systematically studied the influences of annealing atmosphere on the structural and optical properties of Al-doped ZnO (AZO) powders by performing anneals in N2, Ar2, H2 and O2 atmospheres. The results indicated that the optical properties were highly influenced by the annealing atmosphere, which were more pronounced for the AZO powders annealed in forming gas and an oxygen atmosphere. The E1 (LO) vibration mode in the Raman spectra exhibits a good correlation with the green emission and is demonstrated to be originated from VO defects. We conclude that both VO and Oi defects give rise to the green photoluminescence in ZnO, and each will play a dominant role in oxygen-deficient and oxygen-rich environments, respectively.