Lab-on-A-chip compatible design laying over nanostructured silicon

Abstract

Silicon nanopillars are effective nanostructured platforms for deposition of plasmonic nanodisks. One can deposit multiple thin-film layers on SiNPs, which might not be easily feasible using lift-off approach. For Raman sensing, one needs to enhance the E-field at hot-spots. Hybridization of Plasmonic disks can result in high localization at hot-spots. Hybridization happens for Plasmonic nanostructures on top of each other, depending on the gap between the nanostructures. This significantly enhances electric field resulting from confinement at the edges of the Plasmonic nanostructures specially if we have Odd modes present at frequency of laser excitation. The hybridization of Au/SiO 2 /Au has been visualized with the aid of Finite Difference Time Domain method for a laser with a wavelength of λ = 633 nm. Effectiveness of coupling of incident beam at different angles over Metal/Insulator/Metal has been evaluated using numerical simulations. Metal/Insulator/Metal has been deposited over SiNP, fabricated by Interference Lithography using a 3ns, 355 nm pulsed laser. The resulting Raman scattering enhancement from Thionine molecule at the proximity of the nanostructured Metal/Insulator/Metal is measured. Different dielectric thicknesses between Plasmonic disks of Metal/Insulator/Metal structures has been tested successfully for Raman application verifying the effect of hybridization on field enhancement. • This field enhancement is dependent on SiNP dimensions. We have placed two plasmonic gold nanodisks on top of each other over SiNP. The effect of SiNP dimension is observed experimentally.