Effect of Cu surface treatment in graphene growth by chemical vapor deposition

Cu foils with various initial roughness were prepared and graphene was grown on each Cu foil. Graphene nuclei density was highly related to the initial surface roughness of Cu foil. Smoothing was done on Cu foil and initial roughness was relieved during 3 h annealing, but Cu surface with high surface roughness and impurity atoms provides larger nuclei density for the graphene growth. Heteronuclei effect of size variations of impurity atoms on multilayer graphene formation was calculated. Electropolishing was carried out to suppress the heteronuclei effect and the nuclei formation on Cu surface as well. For electropolished Cu substrate, nuclei density of graphene was extremely low even without extended pre-annealing step. (C) 2018 Elsevier B.V. All rights reserved.