Synthesis and optical property of ZnO nanonail arrays with controllable morphology

ZnO nanonail arrays with controllable morphology were prepared via a modified thermal-evaporation process without catalysts. Scanning electron microscopy images show the vertical growth of ZnO nanonails with the different size from silicon substrate. X-ray diffraction pattern and transmission electron microscopy images reveal that the single crystal nanonails grow preferentially along (0 0 0 1) growth orientation. Detailed structural analysis indicates that the substrate temperature and oxygen concentration play a key role in the controllable growth of nanonails. The growth mechanism is revealed and the detailed growth process is also speculated. In addition, the prepared samples display an excellent optical property, suggesting potential application of aligned ZnO nanonails in efficient nano-optoelectronic devices.