Effect of Chemical Treatment and Thermal Annealing in N2 Atmosphere on Copper Foil Surface for Graphene Growth by Direct-Liquid-Injection Chemical Vapor Deposition Process

Abstract

Copper foils are widely used as a substrate for graphene grown by chemical vapor deposition method. The qualities of Cu foils can significantly affect the characters of resulting graphene films. Here, we systematically investigated the effects of chemical treatments and thermal annealing at high temperatures (890-950 °C) in N2 atmosphere. We then compared the graphene quality grown by direct liquid injection chemical vapor deposition (DLI-CVD) method with cyclohexane (C6H12) precursor on un-treated and treated Cu foil. We found that the chemical treatment conditions can improve surface morphology of the Cu foil. In addition, the annealing process at 920 °C for 10 min in N2 atmosphere can increase the grain size and lead to a favorable crystal orientation of (111) plane. Raman and microscopy analyses of the graphene film, show higher yields of monolayer graphene, while, at other annealing conditions and un-treated Cu foil, multilayer graphene is observed.