Large-Scale Fabrication of 5 nm Plasmonic Hybrid Nanoslit Arrays

Surface plasmon resonance harnessed through nanometer-scale metallic gaps generates intense near-fields, unlocking vast potential for applications in nanophotonics and biosensing. However, the scarcity of scalable and reproducible nanofabrication techniques capable of achieving a sub-10 nm gap remains a significant barrier to widespread implementation. Here, we present a high-throughput method combining deep-UV interference lithography, molecular self-assembly, and peeling to fabricate large-scale arrays of an ∼ 5 nm Au-Ag hybrid nanoslit. These arrays serve as highly effective substrates for surface-enhanced Raman spectroscopy (SERS), demonstrating the ability to detect rhodamine 6G at concentrations as low as 1 pM with an analytical enhancement factor of 2.2 × 10⁷. Specifically, the hybrid nanoslit arrays exhibit significantly higher (by 2.6-fold) field enhancements than monolithic nanoslit arrays due to the in-phase hybridization mode in Au-Ag nanoslit. Our cost-effective, large-scale approach overcomes traditional scalability and hybrid patterning barriers, offering transformative potential for sensitive, reliable SERS-based detection platforms.