High intrinsic lattice thermal conductivity in monolayer MoSi2N4

Jihai Yu,Qingfang Li,Xiangang Wan,Jian Zhou

doi:10.1088/1367-2630/abe8f7

Abstract

Very recently, a novel two-dimension (2D) MXene, MoSi2N4, was successfully synthesized with excellent ambient stability, high carrier mobility, and moderate band gap (2020 Science 369 670). In this work, the intrinsic lattice thermal conductivity of monolayer MoSi2N4 is predicted by solving the phonon Boltzmann transport equation based on the first-principles calculations. Despite the heavy atomic mass of Mo and complex crystal structure, the monolayer MoSi2N4 unexpectedly exhibits a quite high lattice thermal conductivity over a wide temperature range between 300 to 800 K. At 300 K, its in-plane lattice thermal conductivity is 224 Wm−1 K−1. The detailed analysis indicates that the large group velocities and small anharmonicity are the main reasons for its high lattice thermal conductivity. We also calculate the lattice thermal conductivity of monolayer WSi2N4, which is only a little smaller than that of MoSi2N4. Our findings suggest that monolayer MoSi2N4 and WSi2N4 are potential 2D materials for thermal transport in future nano-electronic devices.

Highlights

Since the successful exfoliation of monolayer graphene [1], there have been extensive efforts to find novel two-dimensional (2D) materials due to their unusual mechanical, thermal, optoelectric, piezoelectric, and thermoelectrical properties[2-10]
It is found that monolayer MoSi2N4 exhibits an indirect band gap of 1.77 eV with the valence band maximum (VBM) and conduction band minimum (CBM) located at Γ and K points, respectively, which is consistent with the previous studies[25, 27, 29, 30]
The wide band gap implies that the lattice thermal conductivity is dominant in the total thermal conductivity of monolayer MoSi2N4

Summary

Introduction

Since the successful exfoliation of monolayer graphene [1], there have been extensive efforts to find novel two-dimensional (2D) materials due to their unusual mechanical, thermal, optoelectric, piezoelectric, and thermoelectrical properties[2-10]. Owing to these unique properties, 2D materials have become promising candidates for optoelectronics[11], field-effect transistors[12], and energy applications[13,14]. Many classes of monolayer 2D materials have been fabricated, such as transition metal dichalcogenides[2,15], h-BN[16], phosphorene [17], borophene[18], and silicene[19]. It may have difficulties if these monolayer materials are directly applied in integrated nanoelectronic devices because of their restricted properties. The discovery of a desirable monolayer 2D material with a moderate band gap and high carrier mobility remains a primary research goal in materials science and physics

Methods

Results

Conclusion