Hybrid Au nanodisk–nanohole photonic crystals fabricated by laser interference lithography for large-scale, reproducible-performance, low-power and fast-sensing SERS platforms

Abstract

Nanostructured metallic photonic crystals have demonstrated great potential for high-sensitivity, fast, and reproducible molecular detection using surface-enhanced Raman spectroscopy (SERS). In this work, we illustrate an easy procedure to fabricate high-performance SERS platforms (on >2 cm² scales) from hybrid Au nanodisk–nanohole arrays produced via single-beam laser interference lithography (LIL). The SERS performance was investigated by confocal Raman microscopy using methylene blue (MB) as a Raman probe. The characteristic Raman signals were easily detected with good spectral resolution, low laser power (4–40 µW) and short acquisition times (1–30 s) for MB surface densities as low as 2.6 ng cm⁻². In particular, the SERS signals showed exceptionally good reproducibility, with a standard deviation of approximately 12%, confirming its suitability for accurate quantitative sensing applications. A reproducible SERS enhancement factor of (2.4 ± 1.0) × 10⁸ was obtained, which is comparable to conventional values obtained using previously reported photonic crystal-based SERS platforms, and is a new record concerning the values of those fabricated using LIL (10⁴–10⁷).