Hybrid metal-dielectric gratings (HMDGs) as an alternative UV-SERS substrate.

Abstract

Ultraviolet surface-enhanced Raman scattering (UV-SERS) typically occupies an important position because the electronic absorption bands of many biomolecules are located in the deep-ultraviolet (DUV) or ultraviolet (UV) region. Practical application of UV-SERS still relies on uniform, reproducible, and affordable substrates. The conventional aluminum (Al) plasmonic nanostructures are mostly applied to act as UV-SERS substrates, but their intrinsic ohmic loss hinders their practical application. In this study, wafer-scale hybrid metal-dielectric gratings (HMDGs) consisting of aluminum and silicon (Al-Si) have been successfully fabricated as UV-SERS substrates to reduce ohmic dissipation and elevate the detection performance. Well-defined HMDG substrates exhibit tunable hybrid resonant modes in the UV and the visible regions. The adenine biomolecules deposited on HMDG substrates are used to perform SERS measurement with an excitation wavelength of 325 nm. The HMDG nanostructures can obtain as high as 5 orders of magnitude compared with that of Al film as UV-SERS substrates. The proposed HMDG nanostructures have a great advantage in detecting important biomolecules as UV-SERS substrates.