Abstract
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.
Highlights
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
We focused on a feasible way to build a simple and universal surface-enhanced Raman scattering (SERS) substrate scheme by combining the plasmonic metal structure and the dielectric film
We proposed and demonstrated a quasithree-dimensional plasmonic hotspots platform based on a metal-dielectric-metal triple layer structure
Summary
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 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. 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 suggesting a feasible way for a large-area and lowcost SERS platform. The Raman vibrational bands or the chemical signal of the molecules can be strongly enhanced due to the strong EM field transferred to the shell surface by the metal nanoparticles. Many great efforts have been made in efficient SERS by physical or chemical methods for the substrates, the feasible way for large-area, low requirement of fabrication techniques, as well a large spatial distribution density of EM hot spots, has long been pursued
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