Micro-Raman investigation of Ag/graphene oxide/Au sandwich structure

In this study, a silver/graphene oxide/gold sandwich structure was explored, in which the graphene oxide film is inserted between magnetron sputtered gold and silver thin films. Under laser excitation at low intensity, enhancement effects occur in the so-called 'hot-spots', (i.e. spatially localized surface plasmon resonances where the electric field of the laser may generate huge local enhancements of Raman scattering). This aspect was not reported in previous works on sandwich-structured composites, and such results contribute to improving the understanding of GO interaction with magnetron sputtered metal thin films. Micro-Raman technique, Scanning Electron Microscope characterization, Energy-dispersive x-ray spectroscopy analysis and Variable Angle Spectroscopic Ellipsometry were performed. The hot spots activity is associated to the presence of silver nanoparticles, of diameters 40/50 nm, as revealed by Scanning Electron Microscope characterization. Moreover, the distribution of Ag, GO and Au was proved by Energy-dispersive x-ray spectroscopy analysis.