Surface‐Enhanced Raman Scattering in BIC‐Driven Semiconductor Metasurfaces

Abstract

Semiconductor‐based surface‐enhanced Raman spectroscopy (SERS) substrates, as a new frontier in the field of SERS, are hindered by their poor electromagnetic field confinement and weak light‐matter interaction. Metasurfaces, a class of 2D artificial materials based on the electromagnetic design of nanophotonic resonators, enable strong electromagnetic field enhancement and optical absorption engineering for a wide range of semiconductors. However, the engineering of semiconductor substrates into metasurfaces for improving SERS activity remains underexplored. Here, an improved SERS metasurface platform is developed that leverages the combination of titanium oxide (TiO2) and the emerging physical concept of optical bound states in the continuum (BICs) to boost the Raman emission. Moreover, fine‐tuning of BIC‐assisted resonant absorption offers a pathway for maximizing the photoinduced charge transfer effect (PICT) in SERS. High values of BIC‐assisted electric field enhancement (|E/E0|2 ≈103) are achieved, challenging the preconception of weak electromagnetic (EM) field enhancement on semiconductor SERS substrates. The BIC‐assisted TiO2 metasurface platform offers a new dimension in spectrally‐tunable SERS with earth‐abundant and bio‐compatible semiconductor materials, beyond the traditional plasmonic ones.

SERS microscopy as a tool for comprehensive biochemical characterization in complex samples

“…The use of non-plasmonic SERS probes, such as zinc oxide semiconductor nanoprobes that rely on exciton resonances to obtain improved Raman signals of cells 58 or black titanium dioxide particles 59 has led to a number of applications in tumor diagnostics and other biodetection applications of SERS. Substrates consisting of titanium dioxide, such as semiconductor structures that can provide an electromagnetic field enhancement by optical bound states in the continuum, 60 together with a photoinduced charge transfer, or in microspherical arrays that provide unique Mie resonances 61 could be envisioned to be employed for the SERS characterization of complex samples such as cells and tissues as well.…”