Porous Nanostructures by Low Vacuum Sputtering for Surface Enhanced Raman Scattering

Abstract

Surface enhanced Raman scattering (SERS) can greatly enhance the Raman scattered signal and result in applications in material analyses and detection of a small number of molecules. Various studies are being pursued on SERS substrates, and in particular, Ag-based substrates have been studied most extensively because of their relatively high sensitivity. In the present study, the applicability of SERS substrates was tested by designing a method for forming an Ag nanoporous metal structure on a Si substrate by using a sputtering system loaded with a cluster source. The Ag nanoporous structure was formed uniformly on the Si surface under various conditions, and as the working pressure was increased from 10 to 50 mTorr, the gaps between the metal clusters and crystal sizes increased, resulting in the formation of a more porous metal structure. When the cluster source temperature was increased, the deposition rate and porosity decreased, while the crystal size remained constant at 12.5 nm. The Raman response function of the Ag nanoporous structure sample fabricated with the use of a sputtering system loaded with a cluster source showed the maximum peak value for Rhodamine 6G (R6G) at 1514/cm, and when the working pressure was 30 mTorr, the enhancement factor (EF) was 1.92 x 10(6), which confirmed its applicability as a SERS substrate.