High intrinsic lattice thermal conductivity in monolayer MoSi ₂N ₄

Abstract

Very recently, a novel two-dimension (2D) MXene, MoSi ₂N ₄, 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 MoSi ₂N ₄ 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 MoSi ₂N ₄ 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 WSi ₂N ₄, which is only a little smaller than that of MoSi ₂N ₄. Our findings suggest that monolayer MoSi ₂N ₄ and WSi ₂N ₄ are potential 2D materials for thermal transport in future nano-electronic devices.