Effect of Plasma Power on Growth of Multilayer Graphene on Copper Using Plasma Enhanced Chemical Vapour Deposition

Abstract

Large-area multilayer graphene was synthesised on Cu foil by DC plasma-enhanced chemical vapour deposition (DC PECVD) at a relatively low temperature. We discuss the growth mechanism of graphene in the plasma environment by the PECVD method based on the results of X-ray photoelectron spectroscopy, scanning electron microscopy and Raman scattering. Also, the I–V characteristics of graphene synthesised at different plasma powers was studied with a Keithley 2361 system. Due to the advantages of plasma growth, graphene synthesised under DC plasma exhibits better crystallinity, higher growth rate and large grain size at relatively low temperatures. At a plasma power of 100 W, the grain size of graphene (~5 μm) can be increased by a factor of 5. Raman spectroscopy showed D, G and 2D bound in our graphene samples while we find that the intensity of the D peak decreases by increasing the plasma power in growth conditions, which means that the defect density is reduced by the use of the plasma. The XPS results from the sample with maximum plasma power confirm the existence of sp2 carbon atoms (C=C), which indicates the successful formation of graphene onto Cu foil by PECVD. In addition the increase of plasma power is attributed to larger grain sizes, thus leading to the increase of mobility and current change. This investigation shows that DC PECVD is a simple and effective technique to synthesise large-area multilayer graphene, which has potential for application as electronic devices.