Fabrication, structural characterization and the photoluminescence properties of ZnO nanoneedle arrays

A simple thermal evaporation technique, oxidizing zinc foils and in situ evaporating at 500-550 °C, was developed to prepare ZnO one-dimensional nanostructures. Most of the nanostructures were nanoneedles with aligned direction, tens of nanometers in diameter. The nanoneedles were single-crystalline structure, with the axes preferentially aligned along the [0 0 0 1] direction. Room temperature photoluminescence spectrum of the ZnO nanoneedles shows a near band-edge emission (peak at 380 nm) and a deep-level green light emission (peak at 510 nm). The green light emission of the ZnO nanoneedles may be ascribed to the existence of defects such as the singly ionized oxygen vacancies formed in the ZnO nanoneedles. The ZnO nanoneedles offer potential applications as probing tips with high spatial resolution, field-emission tips, and atomic force microscopy tips.