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 mm to 20 mm, the field enhancement factor (b) 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 b by simply changing fiber diameter, but also gives insight for a photo-assisted field emission nano cathode.

Carbon Nanotubes as a Pulsed Electron Sources

“…, G band appears , which is in agreement with the typical Raman feature of multi-walled CNTs [4,14]. To further characterize the detailed information of the CNT arrays covered on the surface of fiber substrate, the X-ray diffractometer is employed to analyze.…”

“…The surface morphology of the CNTs 70528tips are showed in Figure 8(b), and a magnified top view image shows in Figure 8(d). Though the dense roots of CNT arrays vertically attach on the fiber surface, the tips radiate outward dispersedly along the radial direction of fiber substrate [14]. With the fiber diameter decreased, the gaps between the CNT arrays tips are obviously distinct.…”

“…Moreover, the ratio of intensities of the D and G bands, which is less than one indicates a high quantity of structure defects. And, the second-order 2D band, which is caused by the double resonant Raman scattering with twophonon emissions, appears at 2700 cm −1 [4,14]. Carbon Nanotubes as a Pulsed Electron Sources http://dx.doi.org/10.5772/intechopen.70528 53…”

“…With the fiber diameter decreasing, the gaps of tips enlarge and β increase subsequently because of weakening screening effect of CNT emitters. [14]. To illustrate the screening effect on the tips of CNT arrays, a simple electrostatic simulation is carried out by commercial software (Comsol 3.5a, emes mode of AC/DC Module).…”

Electronic Pulses from Pulsed Field Emission of CNT Cathodes

“…CNTs were synthesized on SiO 2 substrate by chemical vapor deposition (CVD) using iron phthalocyanine. The detailed information about the growth of CNTs was reported in our previous research [25]. Field emission tests were performed in a vacuum chamber with pressure about 5 × 10 −5 Pa. A DC bias voltage was applied between the anode and cathode to establish a static electric field by Stanford Research Systems MODEL PS325.…”