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 pho-toluminescence 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 5μm,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/μm at current density of 1μA/cm~2 and a threshold field of 4.92 V/μm at current density of 1 mA/cm~2 at an emitter-anode gap of 700μm.The current density rapidly reached 2.26 mA/cm~2 at an applied field of 5.38 V/μm.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.