Effects of silicon dioxide surface roughness on Raman characteristics and mechanical properties of graphene

The effects of the surface roughness of a silicon dioxide substrate on the mechanical properties and Raman scattering of graphene prepared by chemical vapor deposition were investigated. Analysis of the Raman spectra of the graphene indicated that the strain induced on areas with different surface roughness was the main cause of a shift in the 2D band. Phonon scattering decreased the phonon velocity and the full width at half-maximum of the 2D band. Owing to the greater surface roughness, the shear stress was much greater at the interface between the graphene and the substrate than in other areas. These results provide a method of enhancing the interfacial strength to avoid device instability.