Tungsten oxide nanowires prepared by thermal oxidation for application in cold cathode flat panel x-ray source

Tungsten oxide (WO3−X) nanowire field emitters have important applications in vacuum microelectronic devices, such as cold cathode flat panel x-ray sources. In this study, large-area, high current density, and defect-rich monoclinic WO3−X nanowires were directly synthesized on a glass substrate by thermal oxidation. Field emission measurements from a 4.5 × 4.5 cm2 sample show that a turn-on field of 4.8 MV/m and a high current density of 15.2 mA/cm2 were achieved. Stable emission current with a fluctuation of 1.78% was obtained. Furthermore, a flat panel x-ray source with a reflective anode was fabricated using as-grown WO3−X nanowires as the cold cathode. A radiation dose rate of 1.83 mGy/s was obtained at an anode voltage of 60 kV and a current of 484.1 μA. X-ray imaging experiments were carried out and clear imaging results were obtained. This work is significant for promoting the application of WO3−X nanowires in large-area field emission devices.