Surface enhanced spectroscopy with gold nanostructures on silicon and glass substrates

We compared the surface enhanced spectroscopy signal arising from dye molecules (methylene blue, crystal violet and octadecylrhodamine B) deposited on gold nanostructures fabricated onto two kinds of substrates: silicon wafer or glass. For any molecule and excitation wavelength, the observed signal was always higher on glass compared to silicon. This experimental result is confirmed by Finite-Difference Time Domain calculations: the enhancement in the electric field is much higher with gold nanoparticles on glass than on silicon, even if a thin oxide layer is present. These results clearly demonstrate that the nature of the substrate, independently of metallic nanoparticles, is important for the preparation of highly efficient SERS nanostructures.