Field emission properties from the tip and side of multi-walled carbon nanotube yarns Original Research Article

Multi-walled carbon nanotube (MWCNT) yarns were prepared by spinning a bundle of MWCNTs from vertically super-aligned MWCNTs on a substrate, and field emission from the tip and side of the yarns was induced in a scanning electron microscope. We found that the field emission behavior from the tip of the yarn was better than the field emission from the side. The field emission turn-on voltages from the tip and side of MWCNT yarns were 1.6 and 1.7 V/μm, respectively, after the yarn was subjected to an aging process. Both the configuration of the tip end and the body of the yarn were changed remarkably during the field emission. Both the field emission of the tip and side exhibited a transition of the Fowler–Nordheim slope from the region of low voltage to the region of high voltage. From the Fowler–Nordheim plots, the field enhancement factors of field emission from the tip and side, γtip and γside, in the region of high voltage were determined to be 5430 ± 5 and 3940 ± 5, respectively, and their ratio was approximately 1.38:1.