Electron-phonon and phonon-phonon anharmonic interactions in 2H-MoX2 (X=S, Te): A comprehensive Resonant Raman study

Abstract

Transition metal dichalcogenides (TMDs) are layered materials which show excellent potential for nanoelectronic and optoelectronic applications. However, as many of the exciting features of these materials are controlled by the anharmonic effects, a proper understanding of the phonon properties and anharmonicity associated with these materials is essential for the proposed applications to be realized. We present here a comprehensive study on the phonon properties of two different TMDs; viz., MoS2 and MoTe2, as a function of temperature, laser excitations, and polarization, as well as flake-thickness. Our study includes the measurement of anharmonicity in the first-order and higher order Raman scattering processes. The variations in anharmonicity with the thickness of MoS2 and MoTe2 have been explained in terms of their phonon symmetries, electron-phonon coupling, and phonon-phonon interactions. Further, the effect of the underlying substrate on the anharmonic properties of the in-plane and out-of-plane phonons has also been estimated from the Raman measurements, thus elucidating the intrinsic phonon properties of the 2D layered materials.

arXiv comment58 pages (including Supplemental material)

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Cited by in corpus (2)

• Electron-mediated anharmonicity and its role in the Raman spectrum of graphene
• Renormalization of the optical band gap through an effective Thirring interaction for massive Dirac-like electrons