Molecular spectroscopies with semiconductor metasurfaces: towards dual optical/chemical SERS.

Surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful technique for the ultra-sensitive detection of molecules and has been widely applied in many fields, ranging from biomedical diagnostics and environmental monitoring to trace-level detection of chemical and biological analytes. While traditional metallic SERS substrates rely predominantly on electromagnetic field enhancement, emerging semiconductor SERS materials have attracted growing interest because they offer the additional advantage of simultaneous chemical and electromagnetic enhancements. Here, we review some of the recent advancements in the design and optimization of semiconductor SERS substrates, with a focus on their dual enhancement mechanisms. We also discuss the transition from nanoparticle-based platforms to more advanced nanoresonator-based SERS metasurfaces, highlighting their superior sensing performance.