Double resonance Raman modes in mono- and few-layer MoTe${}_2$

Abstract

We study the second-order Raman process of mono- and few-layer MoTe${}_2$, by combining {\em ab initio} density functional perturbation calculations with experimental Raman spectroscopy using 532, 633 and 785 nm excitation lasers. The calculated electronic band structure and the density of states show that the electron-photon resonance process occurs at the high-symmetry M point in the Brillouin zone, where a strong optical absorption occurs by a logarithmic Van-Hove singularity. Double resonance Raman scattering with inter-valley electron-phonon coupling connects two of the three inequivalent M points in the Brillouin zone, giving rise to second-order Raman peaks due to the M point phonons. The predicted frequencies of the second-order Raman peaks agree with the observed peak positions that cannot be assigned in terms of a first-order process. Our study attempts to supply a basic understanding of the second-order Raman process occurring in transition metal di-chalcogenides (TMDs) and may provide additional information both on the lattice dynamics and optical processes especially for TMDs with small energy band gaps such as MoTe${}_2$ or at high laser excitation energy.

10 pages, 5 figures

References in corpus (7)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Anomalous Lattice Vibrations of Single and Few-Layer MoS2
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Theory of double-resonant Raman spectra in graphene: intensity and line shape of defect-induced and two-phonon bands
• Anomalous Raman Spectra and Thickness Dependent Electronic properties of WSe2
• Field-Effect Transistors Based on Few-Layered alpha-MoTe_2

Cited by in corpus (5)

• Raman scattering in transition metal dichalcogenides MTe2 (M = Mo, W)
• Quantum interference effects in resonant Raman spectroscopy of single- and triple-layer MoTe${}_2$ from first principles
• Determination of the thickness and orientation of few-layer tungsten ditelluride using polarized Raman spectroscopy
• Pressure-dependent Semiconductor to Semimetal and Lifshitz transitions in 2H-MoTe${}_2$: Raman and First-principles studies
• Metal-Insulator Transition and Emergent Gapped Phase in the Surface-Doped 2D Semiconductor 2H-MoTe${}_2$