Large-area, lithography-free, low-cost SERS sensor with good flexibility and high performance.

Cost-effective, sensitive and bio-compatible surface-enhanced Raman spectroscopy (SERS) substrate has been in high demand since the Raman spectrum was designated as a significant tool for analyzing the composition of liquids, gases and solids in 1998 [1]. In this research, we presented the design, fabrication and characterization of an improved gold-based SERS substrate. With fine tuning of the SiO2 thickness we achieved a 3.391 times improvement and achieved an enhancement factor of 1.55 * 107 which is 15 times better than the current gold-standard Klarite substrate. Such improvement is ascribed to the localized surface plasmon resonance (SPR) and propagating SPR, which is proved by full-wave finite-difference time-domain simulations.