Electron-Phonon Coupling, Thermal Expansion Coefficient, Resonance Effect and Phonon Dynamics in High Quality CVD Grown Mono and Bilayer MoSe2

Abstract

Probing phonons, quasi-particle excitations and their coupling has enriched our understanding of these 2D materials and proved to be crucial for developing their potential applications. Here, we report comprehensive temperature, 4-330 K, and polarization-dependent Raman measurements on mono and bilayer MoSe2. Phonon's modes up to fourth-order are observed including forbidden Raman and IR modes, understood considering Frohlich mechanism of exciton-phonon coupling. Most notably, anomalous variations in the phonon linewidths with temperature pointed at the significant role of electron-phonon coupling in these systems, especially for the out-of-plane (A1g) and shear mode (E22g), which is found to be more prominent in the narrow-gaped bilayer than the large gapped monolayer. Via polarization-dependent measurements, we deciphered the ambiguity in symmetry assignments, especially to the peaks around ~ 170 cm-1 and ~ 350 cm-1. Temperature-dependent thermal expansion coefficient, an important parameter for the device performance, is carefully extracted for both mono and bilayer by monitoring the temperature-dependence of the real-part of the phonon self-energy parameter. Our temperature-dependent in-depth Raman studies provide a pave for uncovering the deeper role of phonons in these 2D layered materials from a fundamental as well as application point of view.

References in corpus (19)

• Electric Field Effect in Atomically Thin Carbon Films
• Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy
• Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layers
• Phonon anharmonicities in graphite and graphene
• Excitation energy dependent Raman spectrum of MoSe2
• Variation of the fundamental band gap nature in curved two-dimensional WS2
• Resonance effects in the Raman scattering of mono- and few layers MoSe${}_2$
• Davydov splitting and excitonic resonance effects in Raman spectra of few-Layer MoSe2
• Resonant Low Frequency Interlayer Shear Modes in Folded Graphene Layers
• Interplay between Raman shift and thermal expansion in graphene: temperature-dependent measurements and analysis of substrate corrections
• Strain Mapping In Single-Layer 2D Crystals Via Raman Activity
• Direct calculation of the linear thermal expansion coefficients of MoS2 via symmetry-preserving deformations
• Thermal Expansion Coefficient and Phonon Dynamics in Coexisting Allotropes of Monolayer WS2 Probed by Raman Scattering
• Davydov Splitting, Resonance Effect and Phonon Dynamics in CVD grown Layered MoS2
• Anisotropic Electron-Photon-Phonon Coupling in Layered MoS2
• Phonon Anomalies, Orbital-Ordering and Electronic Raman Scattering in iron-pnictide Ca(Fe0.97Co0.03)2As2: Temperature-dependent Raman Study
• Kramer doublets, phonons, crystal-field excitations and their coupling in Nd2ZnIrO6
• Superconducting Fluctuations and Anomalous Phonon Renormalization much above superconducting transition temperature in Ca4Al2O5.7Fe2As2
• Orbiton-Phonon coupling in Ir5+(5d4) double perovskite Ba2YIrO6

Cited by in corpus (4)

• Raman-phonon-polariton condensation in a transversely pumped cavity
• Renormalization of the optical band gap through an effective Thirring interaction for massive Dirac-like electrons
• Interplay of phonons, intertwined density waves, and induced spin density wave in trilayer nickelates Pr4-xLaxNi3O10
• Phonon frequency comb close to an isolated Einstein mode in InSiTe3