Phonon thermal conductivity of monolayer MoS2

Abstract

We use nonequilibrium molecular dynamics modeling using Stillinger–Weber interatomic potential to investigate the thermal properties of monolayer molybdenum disulfide (MoS2) nanoribbons. We study the impact of factors such as length, edge chirality, monovacancies, and uniaxial stretching on the thermal conductivity of MoS2 nanoribbons. Our results show that longer ribbons have a higher thermal conductivity, and the thermal conductivity of infinitely long zigzag and armchair MoS2 nanoribbons is, respectively, 54 W/mK and 33 W/mK. This is significantly lower than the thermal conductivity of some other graphene-like two-dimensional materials such as graphene and boron nitride. While the presence of molybdenum or sulfur vacancies reduces the thermal conductivity of ribbons, molybdenum vacancies have a more deteriorating effect on thermal conductivities. We also have studied the impact of uniaxial stretching on the thermal conductivity of MoS2 nanoribbons. The results show that in contrast to three dimensional materials, thermal conductivity of MoS2 is fairly insensitive to stretching. We have used the phonon dispersion curves and group velocities to investigate the mechanism of this unexpected behavior. Our results show that tensile strain does not alter the phonon dispersion curves and hence the thermal conductivity does not change.

Thermal conductivity and phonon hydrodynamics in transition metal dichalcogenides from first-principles

“…The phonon dispersions were the first features to be studied from a theoretical viewpoint [13,14,15] and the Raman active modes were also experimentally reported [15]. Further theoretical calculations have been able to determine the thermal conductivity from molecular dynamics [16,17,18] and from lattice dynamics using density functional theory (DFT) through the Boltzmann transport equation (BTE) under the relaxation time approximation (RTA) [19]. Recently, more accurate solutions of the BTE [20] have allowed to compute with greater accuracy the thermal conductivity of MoS 2 [21,22].…”

Thermal Conductivity Enhancement in MoS2 under Extreme Strain

“…Small κ could jeopardize heat dissipation of TMD-based electronics, and techniques to enhance the cross-plane thermal conductivity are required. Previous theoretical studies of strain's effect on thermal conductivity in TMDs have reached inconsistent conclusions [38][39][40][41][42], and experimental studies have not yet been reported. Thus, exploring the tunability of thermal conductivity in TMDs with strain will not only have scientific significance, but also inform thermal management techniques in all TMD-based electronic devices.…”

Transient SHG Imaging on Ultrafast Carrier Dynamics of MoS2 Nanosheets

“…In this sense, the existence of the additional phonon at the 50 ps (0.02 THz) oscillation period (Figure e) is attributed to the difference in heat conduction (≈20% in monolayer MoS 2 ) . Further, factors that determine phonon transport in rigid crystalline structures include the vacancy states, elastic states, and the lattice chirality . Thus, for the highly confined van der Waals structure of 2D semiconducting materials with limited influence from defect generation in the stress‐free state, the difference in the lattice chirality should be the major mechanism of acoustic phonon generation .…”

“…Our image‐based TSHG measurement approach, which features superior spatial resolution and lattice orientation‐selectivity, makes it possible to directly compare the difference between ultrafast quasiparticle dynamics generated not only from the layer thickness but also the chirality, which is occasionally observed during the fabrication of 2D materials. The edge chirality of 2D materials plays a critical role in determining various material characteristics, such as lattice vibration, conductivity, and carrier transport . Theoretically, the armchair edge of MoS 2 is known to experience a drastic bandgap shift between semiconducting and metallic properties in the presence of an electric field, while the carrier transport is more efficiently passivated at zigzag (ZZ) edges .…”

“…While there is a solid role of the incoherent vibration of the lattice in heat conductance, the coherent acoustic phonon has been proposed as a successful alternative route for heat transfer . In this sense, the existence of the additional phonon at the 50 ps (0.02 THz) oscillation period (Figure e) is attributed to the difference in heat conduction (≈20% in monolayer MoS 2 ) . Further, factors that determine phonon transport in rigid crystalline structures include the vacancy states, elastic states, and the lattice chirality .…”