SERS enhancement on monolayer MoS2 films enabled by argon–oxygen plasma treatment

MoS₂ has recently garnered significant attention as a semiconductor-based surface-enhanced Raman scattering (SERS) substrate. However, SERS enhancement and sensitivity are comparatively lower than those of high-conductivity metals, limiting its practical applications. In this study, we report a facile plasma engineering approach to tune the atomic structure of monolayer MoS₂ (ML-MoS₂) SERS substrates. We demonstrate that Ar–O₂ plasma treatment can induce oxygen incorporation and create physical defects, which alters its electronic properties and enhances the charge transfer efficiency between the MoS₂ substrates and the probe molecules, ultimately leading to a significant enhancement in the SERS performance. When using R6G as a probe molecule, the enhancement factor reaches up to 1.14 × 10⁴, with a minimum detection limit as low as 10⁻¹⁰ M. Our results open new avenues for optimizing SERS substrates in ML-MoS₂ and other transition metal dichalcogenides films.