Rolled-Up Ag-SiOx Hyperbolic Metamaterials for Surface-Enhanced Raman Scattering

A convenient technique is reported to fabricate Ag-SiOx hyperbolic metamaterials (HMMs) as robust surface-enhanced Raman scattering (SERS) substrates based on roll-up nanotechnology. As an illustration, dramatic enhancement is achieved using Rhodamine 6G as a molecular probe, which indicates that a larger plasmonic density of states exist, leading to a greatly enhanced local electromagnetic (EM) field when the sample is irradiated with a laser beam. Optimized results are obtained by controlling the thickness of alumina coating onto Ag-SiOx HMMs using atomic layer deposition. Finite-difference time-domain simulations further illustrate the excitation of localized surface plasmon modes by calculating the EM field properties on the surface of Ag-SiOx HMMs. This efficient method of producing Ag-SiOx HMMs with highly SERS-active properties could spur expanding applications in metamaterials and bioanalysis.