A first-principles study of phonon transport properties of monolayer MoSe<inf>2</inf>

Abstract

MoSe 2 as one of the promising two-dimensional transition metal dichalcogenides (TMDCs) recently emerged as promising alternative of graphene for nano-electronic and opto-electronic devices. However, the heat removal is a critical issue for devices using two-dimensional (2D) materials, and low thermal conductivity of monolayer MoSe 2 can significantly affect the performance and reliability of electronic devices. In this study, we use the density functional theory (DFT) and the phonon Boltzmann transport equation (BTE) to study the phonon transport properties of monolayer MoSe 2 and compared the results with MoS2. The iterative solution of the BTE is used to predict the thermal conductivity of MoSe 2 , which is compared with the relaxation time approximation. Model for considering effect of sample size and defects are developed for monolayer MoSe 2 . Our results show the impact of sample size, Se vacancies, boundary and anharmonic phonon scattering on the thermal conductivity of MoSe 2 . Defect model is built based on the phonon scattering caused by the missing atom mass and the change of force constants between the under-coordinated atoms near the vacancies. Results indicate that the presence of 1%, 2% and 4% Se vacancies decrease the thermal conductivity of monolayer MoSe 2 by 11.2%, 23.4% and 46.2% at room temperature. The results from this work will help in understanding the mechanism of phonon transport in 2D materials and provide insights for the future design of MoSe 2 -based electronics.