Highly sensitive and homogeneous SERS substrate fabricated by a femtosecond laser combined with dewetting

We report a simple, cost-effective and repeatable method for fabricating a large area and uniform substrate for surface-enhanced Raman scattering (SERS). The silicon, micromachined by a femtosecond laser, is coated with gold film and then treated through the dewetting process. The morphology shows a higher electric field enhancement due to light trapping. The enhancement factor of the SERS substrate is 9.2 × 10⁷ with a 5 nm-thick film coated. Moreover, it also exhibits a uniform signal through Raman mapping and chemical stability with the greatest intensity deviation of 6% after a month. The proposed technique provides an opportunity to equip microchips with the SERS capabilities of high sensitivity, chemical stability, and homogeneous signals.