Vertically aligned ZnO nanowires produced by a catalyst-free thermal evaporation method and their field emission properties

Vertically aligned ZnO nanowires have been synthesized on Si substrate by catalyst-free thermal evaporating metallic zinc powder at a low temperature of 600°C. Studies found that the ZnO nanowires are single-crystalline wurtzite structures with 70 nm in diameter and 10 μm in length. The turn on field of the ZnO nanowires was about 6.2 V/μm at a current density of 0.1 μA/cm², and the emission current density reached 1 mA/cm ² at an applied field of about 15.0 V/μm. Field emission property from the ZnO nanowires was enough high level to be applicable to field emission displays and vacuum microelectronic devices.