Raman Spectroscopy Study on the Graphene Induced Surface Reconstruction

Abstract

The surface morphology of copper (Cu) often changes during graphene synthesis by chemical vapor deposition (CVD)

the change is attributed to the thermal expansion coefficient mismatch between graphene and Cu. However, the obvious relationship between the reconstructed Cu surface and graphene is not totally understood yet. Here we synthesized graphene with different layer numbers using a CVD system by controlling the gas flow and time. Atomic force microscopy (AFM) images and the Raman G and 2D peaks show that Cu step edges became noticeably broader with increasing graphene layer number. Furthermore, ?ω_G??ω_2D plot indicates that the biaxial compressive strain on monolayer graphene was higher than that on bi/trilayer graphene, which agrees overall with topographic AFM images. Our results suggest that stress relaxation from the less strained bi/trilayer graphene crucially affects Cu surface reconstruction.