Intrinsic Thermal conductivities of monolayer transition metal dichalcogenides MX2 (M\u2009=\u2009Mo, W; X\u2009=\u2009S, Se, Te)

Muhammad Zulfiqar,Geng Li,Jun Ni,Yinchang Zhao,Zhengcao Li

doi:10.1038/s41598-019-40882-2

Abstract

The successful synthesis of the single to few layer transition metal dichalcogenides has opened a new era in the nanoelectronics. For their efficient implementations in the electronic devices while taking care of their overheating issues, the characterization of their thermal transport properties is extremely vital. So, we have systematically investigated the thermal transport properties of monolayer transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te) by combining the first-principles calculations with Boltzmann transport equation. We find that monolayer WTe2 possesses the lowest lattice thermal conductivity κL (33:66 Wm−1K−1 at 300 K) among these six semiconducting materials, in contrast to the highest κL (113:97 Wm−1K−1 at 300 K) of WS2 among them. Further analyses reveal that the higher (lower) anharmonic and isotopic scatterings together with the lower (higher) phonon group velocities lead to the lowest (highest) value of κL in WTe2 (WS2) monolayer. In addition, we have also calculated the cumulative thermal conductivity κC as a function of mean free path, which indicates that the nanostructures with the length of about 400 nm would reduce κL drastically. These results offer important understanding from thermal conductivity point of view to design the 2D transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te) electronics.

Highlights

In the past few years, two-dimensional (2D) materials like graphene have attracted great attention owing to the unique properties related to low dimensionality[1]
transition metal dichalcogenides (TMDC) MX2 crystal become thinned to the monolayers, which provides more possibilities to manipulate the electronic dispersion of TMDC MX2 monolayers at nanoscale[5]
From some classical molecular dynamics (MD) simulations implemented with empirical inter-atomic potentials, it is reported that the thermal conductivity of the single-layer MoS2 is found less than 10 W/mK27,28, as compared to the measured thermal conductivities for the single-layer and multilayer MoS2 which are usually larger than 30 W/mK10,29

Summary

Introduction

In the past few years, two-dimensional (2D) materials like graphene have attracted great attention owing to the unique properties related to low dimensionality[1]. The TMDC MX2 monolayers are good candidates for spintronics and valleytronics researches[7,8] In all of these applications, thermal properties have significant influences on the performance of the devices. From some classical molecular dynamics (MD) simulations implemented with empirical inter-atomic potentials, it is reported that the thermal conductivity of the single-layer MoS2 is found less than 10 W/mK27,28, as compared to the measured thermal conductivities for the single-layer and multilayer MoS2 which are usually larger than 30 W/mK10,29 Owing to this large variance in the results, so far reported in literature, here we are encouraged to present a detailed study on the intrinsic lattice thermal conductivities of TMDC MX2 (M = Mo, W; X = S, Se, Te) monolayers. The cumulative thermal conductivity κC as a function of mean free path, clearly indicates that nanostructuring up to the length of 400 nm would reduce κL drastically which differ from graphene

Methods

Results

Conclusion