Wafer-scale fabrication of high-density nanoslit arrays for surface-enhanced Raman spectroscopy

Surfaces with a periodic nanostructure and controllable feature size are sought after for optical applications, and the fabrication of such surfaces in large areas with high reproducibility, good stability and low deviation is very important. We present a strategy to fabricate large-area nanoslit arrays with controllable pitches and gaps. Au nanoslit arrays with gaps down to around 10 nm and a high gap density of 2.0 × 10⁴ cm^-1 have been fabricated, which can greatly enhance the near-field electromagnetic field to achieve localized surface plasmon resonance (LSPR). An averaged surface-enhanced Raman scattering analytical enhancement factor of 8.0 × 10⁷ has been achieved on the substrate using a 633 nm laser source and the 'coupling effect' of LSPR of the nanoslits.