Field emission properties of graphenated multi-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition

Abstract

Graphenated multi-wall carbon nanotube (g-MWCNTs) were obtained by means of plasma enhanced chemical vapor deposition (PECVD). The effect of C2H2/H2 gas ratio was assessed and the threshold point at which the graphenated MWCNTs morphology changes was identified. A minimum amount of carbon feedstock is required for the growth of vertically aligned g-MWCNTs (VA-g-MWCNTs). The field electron emission (FEE) properties of the VA-g-MWCNTs were systematically investigated as a function of emitters' length. Variation of the growth temperature between 550 and 700 °C yielded g-MWCNTs with lengths between 0.12 and 4.36 μm. The increase in emitter length has for effect to lower the electrical field needed to maintain continuous emission by decreasing it from 7.15 to 1.8 V/μm. The field enhancement factor is shown to vary between 640 and 4865 over this range, indicating that length of the g-MWCNTs is a critical parameter for the efficient extraction of electron. In addition to the high field enhancement factor, the local electrical field at the tip of the g-MWCNTs was calculated and advantageously compared with already reported values meaning that this unique structure is well suited for field emission purposes.