2D-MoS_(2)热输运的温度与尺寸依赖性研究

Study on Temperature and Size Dependence of Thermal Transport in 2D-MoS_(2)

本文基于第一性原理计算结合声子玻尔兹曼输运方程(BTE),研究了单层MoS_(2)热输运的温度与尺寸依赖性。单层MoS_(2)的热导率主要由TA和LA模式的声子贡献,光学支的贡献极小,并由于带隙的存在与声学声子的散射十分微弱。通过限制具有长平均自由程(MFP)的声子的贡献,体系尺寸的减小也显著限制了热导率。将体系的尺寸限制到100 nm以下后,温度效应的影响不再显著,这归因于本征声子-声子散射与声子-边界散射之间的竞争,并通过散射率的计算进行了证明。

In this paper,based on first-principles calculations combined with the phonon Boltzmann transport equation(BTE),the temperature and size dependence of thermal transport in monolayer MoS_(2)was investigated.The thermal conductivity of monolayer MoS_(2)is mainly contributed by the phonons of TA and LA modes.The contribution of the optical branch mode is very small,and the scattering with acoustic phonons is very weak due to the existence of the band gap.The reduction in system size also significantly limits thermal conductivity by limiting the contribution of phonons with long mean free path(MFP).After limiting the size of the system below 100 nm,the effect of temperature is no longer significant,which is attributed to the competition between intrinsic phonon-phonon scattering and phonon-boundary scattering,and demonstrated by the calculation of scattering rate.