Integrated “Hot Spots”: Tunable Sub‐10 nm Crescent Nanogap Arrays

Abstract Plasmonic crescent nanogap arrays (CNGAs) integrated by nanoscale gaps and nanotips exhibit strong capability of light confinement and thus lead to extremely electric field enhancement. The CNGAs with tunable gap‐width are fabricated via a low‐cost and simple process combining colloidal lithography and nanoskiving techniques. Incident light is captured in the nanogaps and at the two tips of nanocrescent, where extremely strong electric fields are excited. The strong electric fields lead to greatly enhanced surface‐enhanced Raman spectroscopy (SERS) performance with typical enhancement factor of 8 and 360 times in comparison with the crescent gold nanoparticles and linear gold nanowire, and the SERS enhancement factor at CNGAs with G = 1 nm is up to about 6.04 × 10⁸. The CNGAs with strong electric fields and remarkable SERS signals are promising to advance the applications of optical filters, surface‐enhancement spectroscopies, nonlinear optics, single‐molecule analysis, and nanolasing.