Raman enhancement of large-area silver grating arrays based on self-assembled polystyrene microspheres

Two types of Ag grating arrays as surface-enhanced Raman scattering (SERS) were fabricated using the monolayer self-assembled polystyrene (PS) as a template, using the silver film and monocrystalline silicon wafer as the substrates, imprinting different thicknesses of silver (50 nm, 75 nm, 100 nm, 125 nm and 150 nm) on the template, then removing PS. Rhodamine 6G (R6G) was used as a probe to characterize the performance of Raman enhancement. Experimental results showed that two structures can obtain a Raman enhancement factor of more than 107 at arbitrary deposition thicknesses. The insensitivity of two arrays induced by incident polarization and the difference in near-field and far-field simulation were also compared. These novel SERS substrates can achieve considerable uniformity, and the relative standard deviation (RSD) of the characteristic peak calculated at 1650 cm−1 were about 9.2% and 9.5%, respectively.