Multiphonon Raman Scattering in Transition Metal Dichalcogenide Double Layers

Abstract

Herein, multiphonon Raman scattering assisted by the interlayer excitons in double transition metal chalcogenide (TMD) layers based on the Huang–Rhys's model is studied. The processes of multiple longitudinal optical (LO) phonons Raman scattering are presented due to the strong exciton–LO phonon coupling. It is found that the Raman scattering intensity and orders of LO phonon overtones depend on the obtained value of Huang–Rhys factor, which can be tuned obviously by the strength of exciton–LO phonon coupling and interlayer distance between two TMD layers. Meanwhile, temperature dependence of scattering intensities for different orders of LO phonon overtones in the multiphonon processes is discussed. The theoretical results provide significant insight not only for the analysis of multiphonon Raman spectroscopy in experiments, but also for the modulation of optical properties in a series of TMD double layers and Van der Waals heterostructures.