Light-Trapped Nanocavities for Ultraviolet Surface-Enhanced Raman Scattering

Abstract

The fabrication of surface-enhanced Raman scattering (SERS) substrates with large areas, high activities, desirable uniformities, and aggregated hot spots evenly distributed in the UV (ultraviolet) region has been regarded as a formidable task. In the present work, by means of elaborate structure designs and material selections, we have fabricated periodic light-trapped nanocavities that have overcome the abovementioned difficulties. Specifically, a great amount of electromagnetic energy has been localized in nanocavities due to repeated reflections of the trapped incident light, thus re-amplifying abundant hot spots of the aluminum film. At an excitation wavelength of 325 nm, the acquisition of ultrahigh SERS enhancement factors (≳106) has been successfully achieved, and signal intensities are uniformly distributed after repeated measurements. In the originally weak UV region, our nanostructure design and its associated mechanism may provide a guide for future SERS-related research.