Highly sensitive and reproducible SERS substrates of bilayer Au and Ag nano-island arrays by thermal evaporation deposition

We have successfully fabricated bilayer structure of Ag-Au Nano-islands arrays (NIA) by thermal evaporation deposition for surface enhanced Raman scattering (SERS) sensing. The main SERS signal layer is Ag NIA while the present coating of Au nanostructures is beneficial to attenuate the background fluorescence for increasing the signal-to-background (S/B) ratio, and suppress air exposure of highly reactive surfaces of Ag NIA, acted as a passivation layer and improve the reproducibility of SERS detection. The high sensitive and reproducible sandwich structure of our SERS substrate appears to be promising for detection of some biomolecules for biomedical, food safety and new generation of environmental pollutants applications.182