Synthesis and field emission of two kinds of ZnO nanotubes: taper-like and flat-roofed tubes

Two kinds of ZnO nanotubes, including taper-like and flat-roofed tubes, have been successfully fabricated using a simple aqueous solution route by changing the experimental conditions. All the obtained nanotubes have a uniform size of 500 nm in diameter, 10-50 nm in wall thickness, and 2-5 mu m in length. The growth mechanism of two kinds of ZnO nanotubes was investigated. Field emission measurements showed that tapering nanotubes have the good field emission performance with a low turn-on field of similar to 2.1V mu m(-1) and a low threshold field of similar to 3.8V mu m(-1), which suggests the possible applications of the ZnO tubular structures in field emission microelectronic devices.