Effect of catalyst film thickness on the structures of vertically-oriented few-layer graphene grown by PECVD

Abstract

The growth behavior of vertically-oriented few-layer graphene (V-FLG), produced by radio-frequency plasma enhanced chemical vapor deposition (PECVD), is studied here as a function of catalyst and catalyst film thickness. The Co catalyst and catalyst film thickness were observed as being crucial for the growth states and morphology of V-FLG. V-FLG showed a slower growth rate and lower density on substrates without catalyst than with catalyst due to the V-FLG nucleation on the former being prevented. It demonstrates that the growth mechanism of V-FLG on the Co catalyst film is not similar to the catalytic growth mechanism of CNTs, which is a defect nucleation mechanism. During PECVD process, the highly reactive C radicals can preferentially form CNTs or graphite-shell by Co catalysis, then trigger nucleation on the surface of CNTs or graphite-shell for V-FLG growth. The excellent field emission properties of the V-FLG and FLG-CNTs make them promising candidates for high-performance field emission emitters.