Fabrication, characterization and field emission properties of large-scale uniform ZnO nanotube arrays

Large-scale well-aligned ZnO nanotubes with outer diameters of 100-300 nm and lengths of tens of micrometres have been prepared by a template-based chemical vapour deposition method. The photoluminescence spectrum of the ZnO nanotube arrays consists of a strong violet band at 414 nm, a blue band at 462 nm and a weak shoulder peak at around 480 nm. The field emission of the ZnO nanotube arrays shows a turn-on field of about 7.3 V microm(-1) at a current density of 0.1 microA cm(-2) and emission current density up to 1.3 mA cm(-2) at a bias field of 11.8 V microm(-1).