Preparation of a miniature carbon nanotube paste emitter for very high resolution X-ray imaging

A miniature carbon nanotube (CNT) paste emitter dot with a diameter of ∼50 μm was fabricated onto the cross-sectional surface of Kovar (nickel-cobalt ferrous alloy) rod without using a sophisticated photolithography. A highly adhesive CNT paste was prepared with silicon carbide and nickel nanoparticles, and then the small CNT emitter was fabricated by a novel and facile technique, called point contact method. The prepared emitter generates very high current density of ∼11.2 A/cm2 when measured using a diode configuration. We further observed for the first time the brightness of electron beam generated from the CNT paste emitter that is a more practical point electron source than the individual CNT emitter. The triode structure fabricated with a miniature CNT paste emitter and a gate aperture (20 μm in diameter) generated a collimated electron beam by which very high resolution (>16 lp/mm) X-ray imaging was achieved.