Fabrication of Nanostructured ZnO Films for Transparent Field Emission Displays

Abstract

A highly transparent field emitter was achieved by Ar + ion irradiation onto highly transparent and conducting ZnO films deposited on glass substrates. The as-deposited flat ZnO films before ion irradiation, which showed 90% transmittance and 186 Ω/□ sheet resistance, showed no field emission current up to 15 V µm -1 . The ZnO film ion-irradiated at an ion-incidence angle of 45° showed nanocone structures about 200–400 nm in height and 6–8 µm -2 in number density. Since the nanocone size was less than the wavelength of visible light, the transmittance was maintained at 86% for the ion-irradiated ZnO film. The field emission properties of the ion-irradiated ZnO film revealed that a current density of 1 µA cm -2 was achieved at 6.2 V µm -1 , and that the field enhancement factor was calculated to be 2252 from the Fowler–Nordheim plot. Thus, the nanostructured ZnO film is believed to be promising as a transparent field emitter.