Interaction between Metal and Graphene: Dependence on the Layer Number of Graphene

The interaction between graphene and metal was investigated by studying-the G band splitting in surface-enhanced Raman scattering (SERS) spectra of single-, bi-, and trilayer graphene. The Ag deposition on graphene induced large enhancement of the Raman signal of graphene indicating SERS of graphene. In particular, the G band was split into two distinct peaks in the SERS spectrum of graphene. The extent of the G band splitting was 13.0 cm(-1). for single layer 9.6 cm(-1) for bilayer; and 94 cm(-1) for trilayer. graphene, Whereas the G band in the SERS spectrum of a thick multilayer was not split The average SERS enhancement factor of the G band was 24 for single-layer 15 bilayer, and 10 for trilayer graphene. These results indicate that there is a correlation between SERS enhancement factor and the extent of the G band splitting, and the strongest interaction occurs. between Ag and single layer graphene. Furthermore, the Ag deposition On graphene can induce doping of graphene. The intensity ratio of and G bands (l(2D)/l(G)) decreased after Ag deposition on graphene, indicating doping of graphene. From changes In positions of G and 2D bands after the metal deposition on graphene,Ag deposition induced n-doping of graphene, whereas Au deposition induced p-doping.,