Tunable Photoluminescence of ZnO Nanowire Arrays via Native Defects

Natural ZnO nanomaterials have abundant oxygen vacancies which has great influence on the physical properties. Here, the ZnO nanowire arrays (ZNAs) have been obtained using microwave heating method. These samples' photoluminescence (PL) properties were studied under different annealing conditions. The field emission scanning electron microscope (SEM) image shows that the vertically aligned ZNAs basically have the same morphology after annealing at different times. X-ray diffraction (XRD) spectra demonstrate the best crystallization when the sample was annealed at 400 °C for 2 hours. Photoluminescence pattern indicates that the near-band-edge (NBE) emission is stronger with increasing annealing times, however, the defect-related emission decreases with the annealing times. This result indicates that crystallization of ZnO nanowires can be improved and the defects can decrease by annealing and the crystallization of the sample is wonderful at 400 °C for 2 h annealing. Meanwhile, adjusting photoluminescence characterizes through annealing can provide the basis for application of ZnO in photoelectric device.