High-performance SERS substrate based on gold nanoparticles-decorated micro/nano-hybrid hierarchical structure

Abstract

Owing to its excellent localized surface plasmon resonance (LSPR) effect, noble metal nanoparticles (NPs) find extensive application in the preparation of surface-enhanced Raman scattering (SERS) substrates. However, due to process limitations, the practicality and testing effectiveness of SERS substrates still leaves much to be desired. Here, a wafer-scale gold (Au) NPs silicon (Si) micro/nano-hybrid structured substrate is prepared. This is achieved through two-step etching, followed by decorating Au-NPs onto the structure via self-assembly process induced by de-wetting. Finite-difference time-domain (FDTD) simulations reveal that the significant enhancement of local electric field in the voids between Au-NPs and Si is crucial for enhancing SERS. Using Rhodamine 6G (R6G) as the probe molecule, performance of the fabricated SERS substrate is investigated. It demonstrates a minimum detection limit of 10⁻¹¹ M, with a calculated enhancement factor of 4.40 × 10⁸, indicating its high sensitivity. The minimum relative standard deviation for the substrate is 5.254 %. After 20 days of placement, the SERS performance show tiny variation. Even after four cycles of cleaning experiments, it still maintains outstanding SERS performance. This demonstrates its excellent stability, uniformity and reusability. Our research provides guidance for the efficient and low-cost fabrication of high-performance SERS substrates.