Carbon nanotube cathodes covered on the cylindrical surface of a fiber

Abstract

Carbon nanotube (CNT) arrays were synthesized on the cylindrical waveguide surface of a quartz optical fiber by chemical vapor deposition (CVD) to serve as field emission cathodes. The roots of CNT arrays grew vertically on the fiber surface. Importantly, the change of fiber diameter affected the morphology of CNT tips. With the decrease in the fiber diameter, the gaps between CNT tips enlarged, which greatly improved the field emission properties of CNTs covered on cylindrical fiber surface. When the fiber diameter changed from 200 μm to 20 μm, the field enhancement factor (β) of CNT cathodes increased from 7823 to 11 631. Subsequently, the turn-on voltage (V_to) of CNTs cathodes decreased from 1290 V to 109 V, and the emission current density increased dramatically. In our work, the approach of synthesizing CNTs on optical fiber not only provides a route to improve β by simply changing fiber diameter, but also gives insight for a photo-assisted field emission nano cathode.