Raman spectroscopy of morphology-controlled deposition of Au on graphene

By tuning substrate temperatures in a thermal deposition process, Au nanostructures with different morphologies, such as polygons, dendrites, irregular islands and dense clusters have been obtained on graphene surface. The surface-enhanced Raman scattering (SERS) of graphene caused by gold decoration is systematically investigated. The enhancement factor of graphene G band and the extent of G band splitting are found to be dependent on the morphologies of gold clusters. A maximum enhancement factor as high as ∼270 is obtained for polygonal gold film deposited on monolayer graphene. Furthermore, as a SERS substrate, graphene combined with polygonal gold shows the highest Raman enhancing efficiency for crystal violet (CV) molecules. The mechanisms for the above results are discussed.