Etienne Lorchat

Unified Description of the Optical Phonon Modes in N-Layer MoTe2

N-layer transition metal dichalcogenides provide a unique platform to investigate the evolution of the physical properties between the bulk (three-dimensional) and monolayer (quasi-two-dimensional) limits. Here, using high-resolution micro-Raman spectroscopy, we report a unified experimental description of the Γ-point optical phonons in N-layer 2H-molybdenum ditelluride (MoTe2). We observe series of N-dependent low-frequency interlayer shear and breathing modes (below 40 cm(-1), denoted LSM and LBM) and well-defined Davydov splittings of the mid-frequency modes (in the range 100-200 cm(-1), denoted iX and oX), which solely involve displacements of the chalcogen atoms. In contrast, the high-frequency modes (in the range 200-300 cm(-1), denoted iMX and oMX), arising from displacements of both the metal and chalcogen atoms, exhibit considerably reduced splittings. The manifold of phonon modes associated with the in-plane and out-of-plane displacements are quantitatively described by a force constant model, including interactions up to the second nearest neighbor and surface effects as fitting parameters. The splittings for the iX and oX modes observed in N-layer crystals are directly correlated to the corresponding bulk Davydov splittings between the E2u/E1g and B1u/A1g modes, respectively, and provide a measurement of the frequencies of the bulk silent E2u and B1u optical phonon modes. Our analysis could readily be generalized to other layered crystals.

Direct versus indirect band gap emission and exciton-exciton annihilation in atomically thin molybdenum ditelluride (MoTe2)

We probe the room temperature photoluminescence of

Splitting of Interlayer Shear Modes and Photon Energy Dependent Anisotropic Raman Response in N-Layer ReSe2 and ReS2

N

Rigid-layer Raman-active modes in N-layer transition metal dichalcogenides: interlayer force constants and hyperspectral Raman imaging

-layer molybdenum ditelluride (MoTe

Room Temperature Chiral Coupling of Valley Excitons with Spin-Momentum Locked Surface Plasmons

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Charge Versus Energy Transfer in Atomically Thin Graphene-Transition Metal Dichalcogenide van der Waals Heterostructures

) in the continuous wave (cw) regime. The photoluminescence quantum yield of monolayer MoTe

Spin-momentum locked polariton transport in the chiral strong coupling regime

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Room Temperature Valley Polarization and Coherence in Transition Metal Dichalcogenide-Graphene van der Waals Heterostructures.

is three times larger than in bilayer MoTe

Quantifying Photoinduced Charge Transfer in Graphene-Transition Metal Dichalcogenide van der Waals Heterostructures using Raman Spectroscopy

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Unified Description of the Optical Phonon Modes in

and forty times greater than in the bulk limit. Mono- and bilayer MoTe