Dimensional crossover of acoustic phonon lifetime in $2H$-MoSe${}_2$

Abstract

A time-resolved observation of coherent interlayer longitudinal acoustic phonons in 2$H$-MoSe${}_2$ is reported. A femtosecond pump-probe technique is used to investigate the evolution of the energy loss of these vibrational modes in a wide selection of MoSe${}_2$ flakes with different thicknesses ranging from bilayer up to the bulk limit. By directly analysing the temporal decay of the modes, we can clearly distinguish an abrupt crossover related to the acoustic mean free path of the phonons in a layered system, and the constraints imposed to the acoustic decay channels when reducing the dimensionality. Loses intrinsic to the low dimensionality of single or few layer materials impose critical limitations for their use in optomechanical and optoelectronic devices.

arXiv comment21 pages, 16 figures, submitted material

References in corpus (24)

• Atomically thin MoS2: A new direct-gap semiconductor
• Van der Waals heterostructures
• Excitons in atomically thin transition metal dichalcogenides
• Dimensional crossover of thermal transport in few-layer graphene materials
• Elastic properties of freely suspended MoS2 nanosheets
• Interlayer breathing and shear modes in few-trilayer MoS2 and WSe2
• Large and tunable photo-thermoelectric effect in single-layer MoS2
• Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layers
• Shear and Layer Breathing Modes in Multilayer MoS2
• Thermal conductivity of monolayer MoS2, MoSe2, and WS2: Interplay of mass effect, interatomic bonding and anharmonicity
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Vibrational and optical properties of MoS${}_2$: from monolayer to bulk
• Structural and Electrical Properties of MoTe${}_2$ and MoSe${}_2$ Grown by Molecular Beam Epitaxy
• Valley Carrier Dynamics in Monolayer Molybdenum Disulphide from Helicity Resolved Ultrafast Pump-probe Spectroscopy
• Exciton band structure in layered MoSe2: from a monolayer to the bulk limit
• Force sensitivity of multilayer graphene optomechanical devices
• Resonance effects in the Raman scattering of mono- and few layers MoSe${}_2$
• High quality-factor mechanical resonators based on WSe2 monolayers
• Realization of an atomically thin mirror using monolayer MoSe2
• Unified description of the optical phonon modes in $N$-layer MoTe${}_2$
• Lifetimes of Confined Acoustic Phonons in Ultra-Thin Silicon Membranes
• Sub-harmonic resonant excitation of confined acoustic modes at GHz frequencies with a high-repetition-rate femtosecond laser
• Weakly Trapped, Charged, and Free Excitons in Single-Layer MoS2 in the Presence of Defects, Strain, and Charged Impurities
• Optomechanical measurement of thermal transport in two-dimensional MoSe2 lattices

Cited by in corpus (4)

• Terahertz phonon engineering with van der Waals heterostructures
• Phonon wind and drag of excitons in monolayer semiconductors
• Coupling of MoS${}_2$ Excitons with Lattice Phonons and Cavity Vibrational Phonons in Hybrid Nanobeam Cavities
• Raman Forbidden Layer-Breathing Modes in Layered Semiconductor Materials Activated by Phonon and Optical Cavity Effects