Temperature-dependence on the structural, optical, and paramagnetic properties of ZnO nanostructures

A decreasing trend in the photoluminescence (PL) intensity of a strong broad violet-blue emission from ZnO nanostructures with increasing annealing temperature was also observed. The electron spin resonance (ESR) signal was also found to gradually decrease with increasing annealing temperature indicating the decrease in the concentration of zinc interstitials (Zni) and/or zinc vacancies (VZn) defects in ZnO nanostructures. Moreover, a combination of results from the PL, XPS and ESR suggested that Zn related defects; especially VZn and Zni are the primary source of the paramagnetism observed in the ZnO nanostructures.