LAUSR

Abstract We present a feasible way to strongly enhance Raman signals via introducing an ultra-thin dielectric film in the dual-layer plasmonic hotspots structure, which forms a quasi-three-dimensional structure. The Raman intensity was obtained with an enhancement factor of 735% for the dual-layer metal structure buffered with an ultra-thin silicon film. Moreover, the silicon layer based surface-enhanced Raman scattering (SERS) substrate provided a Raman signal two to five times larger than that of the silica buffered substrate. These distinct responses confirm that the ultra-thin high-index semiconductor film has the capability of additionally enhancing Raman scattering. Otherwise, the upper and lower metal clusters can support multiple kinds of plasmonic resonances, which produce a remarkable physical enhancement of the Raman signals. Besides these impressive optical properties, the substrates have prominent advantages on structural features, since the fabrication process can be fulfilled simply, suggesting a feasible way for a large-area and low-cost SERS platform. The findings may pave an avenue to achieve insights on the dielectric enhanced Raman scattering and hold potential applications in optoelectronics, such as environmental and health sensors.