Fabrication and Simulation of Broadband Surface-Enhanced Raman Spectroscopy (SERS) Based on Disordered Nanoplasmonics

This study investigates the broadband plasmonic resonance properties of gold-based surface-enhanced Raman spectroscopy (SERS) substrates with stochastically disordered nanostructures. We fabricated a nanotextured template topped with sputtered gold. Field emission scanning electron microscopy (FE-SEM) analysis showed random gold nanoclusters with different densities, sizes, and orientations. Simulation results indicated a large number of electromagnetic (EM) modes, including first- and second-generation hotspots as well as touching point geometries that provide a large enhancement factor. With any given excitation wavelength, such disordered SERS structures can provide some mode configurations that resonance, resulting in broadband response. SERS simulations showed considerable electric field intensification across a wide range of wavelengths (600–1600 nm) and provided a relatively uniform SERS response with an areal-averaged enhancement factor ~10 5 across a broad visible to near-infrared range.