Surface-enhanced Raman nanodomes

Abstract

We demonstrate a surface-enhanced Raman scattering (SERS) substrateconsisting of a closely spaced metal nanodome array fabricated on flexible plasticfilm. We used a low-cost, large-area replica molding process to produce atwo-dimensional periodic array of cylinders that is subsequently overcoated withSiO2 and silver thin films to form dome-shaped structures. Finite element modeling was used toinvestigate the electromagnetic field distribution of the nanodome array structureand the effect of the nanodome separation distance on the electromagnetic fieldenhancement. The SERS enhancement from the nanodome array substrates wasexperimentally verified using rhodamine 6G as the analyte. With a separationdistance of 17 nm achieved between adjacent domes using a process that is preciselycontrolled during thin film deposition, a reproducible SERS enhancement factor of1.37 × 108 was demonstrated. The nanoreplica molding process presented in this work allowsfor simple, low-cost, high-throughput fabrication of uniform nanoscale SERSsubstrates over large surface areas without the requirement for high resolutionlithography or defect-free deposition of spherical microparticle monolayer templates.