Annealing induced defects in ZnO nanostructures

ZnO nanostructures that do not exhibit defect-related PL emissions in the as-synthesized form have been exposed to annealing in air and argon environments at 500 degrees C for 2 h. That resulted in the appearance of some intrinsic defects in ZnO nanostructures. Morphology of the nanorods has also been affected by argon annealing. An intense luminescence peak appears in the PL spectra centred at 502 nm in samples annealed in argon. In contrast, the orange/red emission dominates the PL spectra of oxygen annealed nanostructures.