Anomalous Intensity Quenching of Resonant Raman Scattering in Atomically Thin MoS2

Abstract Resonance Raman scattering (RRS) is widely recognized for dramatically enhancing the intensity of Raman modes through the precise tuning of excitation energy to be resonant with the electronic transition energy in semiconductors. However, this work reports that in monolayer flake (1LM), when the excitation energy is resonant with the A‐exciton energy, the and modes exhibit anomalous quenching of the Raman intensity, which is even comparable to that under the non‐resonant condition. This unusually weakened resonant Raman intensity is ascribed to the band filling effect (BFE) caused by the photoexcited carriers at the band edges, which obstructs the Raman scattering pathway related to the band‐edge states. Notably, this quenched Raman intensity can be recovered by introducing non‐radiative relaxation channels of interfacial charge transfer in 1LM‐based heterostructures and intervalley scattering in multilayer to mitigate the BFE. As the BFE is widely present in low‐dimensional semiconductors, this work paves a potential approach to manipulate Raman intensity enhancement by controlling carrier relaxation dynamics in low‐dimensional semiconductors and related heterostructures.