Modeling of Thermal Properties of Semiconducting Monolayer MoSe2 and WSe2

Abstract

In this work, first-principles based calculations of thermal properties of monolayer group-6 transition metal dichalcogenides (TMDs) viz. MoSe2 and WSe2 are reported. Owing to the distinctive electronic, optical, and thermal properties, the TMDs have emerged as the suitable candidates for designing next-generation ultra-thin nanodevices. Thus, accurate estimation of heat dissipation across any two-dimensional (2D) atomically thin layer has become crucial. In order to determine thermal transport, we need to assess different intrinsic properties of the 2D materials. A large value of thermal conductivity will ensure better heat transmission across the channel of any high-performance device. Therefore, modeling of different parameters such as mode dependent group velocities, phonon mean free path, etc. has become extremely important.In this study, we adopt a multi-scale modeling approach for determining phonon group velocities of semiconducting MoSe2 and WSe2 crystals. Room temperature air stability of single layer MoSe2 and single layer WSe2 are comparable with that of the other group-6 TMDs. Moreover, the semiconducting 2H phases of both the crystals are dynamically stable. The results reported in this work will be useful for developing closed-form expression of specific heat and thermal conductivity of semiconducting TMDs which are the potential channel materials for sub-10 nm channel length transistors.