Surface enhanced Raman scattering (SERS) sensors have been fabricated by rapid thermal chemical vapor deposition of high-density nanoscale discrete graphene islands on copper foils followed by electroless chemical plating of discrete, closely spaced, and irregularly shaped silver nanoparticles on the copper surface where it is not covered by graphene islands. By fine tuning of the size and distribution of graphene islands and adjusting the deposition time for silver nanoparticles, nanoscale gaps between silver particles are fabricated. SERS sensors exhibiting Raman scattering signal enhancement factors as high as 1014 in reference to a bare copper have been demonstrated. Raman scattering signal has been measured from as low as 10-16 M of R6G molecules in water. This article reports effects and optimization process of size and distribution of graphene islands on desirable morphology of chemically plated silver nanoparticles. The density of nanoscale gaps of a few nanometers in distance between neighboring silver nanoparticles is optimized, resulting in the demonstration of SERS sensors with very low detection limits for R6G molecules.
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