Dense 2D Arrays of Au@Ag and Au@Ag@Au as Efficient SERS Substrates

Abstract

Surface enhanced Raman scattering (SERS) is recognized as an extremely powerful technique for highly sensitive and spatially resolved detection. This technique takes advantage of the strong near-field light induced by metallic nanostructures to enhance the weak Raman signal of the analyte up to 14 orders of magnitude. Up to now, research on SERS substrates focused on two different approaches, the first relies on top-down techniques, such as lithography, and allows good control of optical properties of the device but has huge limits concerning the scalability of the substrate, which is usually limited a sub millimeters in size; the second relies on bottom-up techniques and usually cannot guarantee high enhancement factor (due to low density of metallic nanostructures) and good reproducibility and is limited to small-size (diameter < 20 nm) nanoparticles. In order to overcome the main issues of the common SERS substrates, we developed a SERS substrate which shows both good control of optical properties and good reproducibility.