Hydrothermally grown ZnO nanorods on self-source substrate and their field emission

Vertically aligned zinc oxide nanorod arrays were grown directly using a zinc foil as both source and substrate in pure water at low temperature by a simple hydrothermal reaction. The morphology and crystal structure of the ZnO nanorod arrays were examined by scanning electron microscopy, transmission electron microscopy and x-ray diffraction, respectively. The nanorods grew along the [0 0 0 1] direction and were 80 nm in diameter and almost 2 mu m in length. Directly employing the zinc foil substrate as cathode, the field emission (FE) of the ZnO nanorods presented a two-stage slope behaviour in a ln(J/E-2)-1/E plot according to the Fowler-Nordheim equation. The FE behaviour was investigated by considering the action of the defects in ZnO nanorods based on the measurement of the photoluminescence.