Synthesis and efficient field emission characteristics of patterned ZnO nanowires

Patterned ZnO nanowires were successfully synthesized on ITO electrodes deposited on the glass substrate by using a simple thermal evaporation approach. The morphology, crystallinity and optical properties of ZnO nanowires were characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray and photoluminescence spectroscopy. Their field emission characteristics were also investigated. SEM images showed that the ZnO nanowires, with a diameter of 100-200 nm and length up to 5 mu m, were highly uniform and well distributed on the linear ITO electrodes. The field emission measurement indicated that patterned ZnO nanowire arrays have a turn-on field of 1.6 V/mu m at current density of 1 mu A/cm(2) and a threshold field of 4.92 V/mu m at current density of 1 mA/cm(2) at an emitter-anode gap of 700 mu m. The current density rapidly reached 2.26 mA/cm(2) at an applied field of 5.38 V/mu m. The fluctuation of emission current was lower than 5% for 4.5 h. The low turn-on field, high current density and good stability of patterned ZnO nanowire arrays indicate that it is a promising candidate for field emission application.