单层MoS_(2)中声子热输运的第一性原理研究

First-principles investigation of phonon thermal transport in monolayer MoS_(2)

基于密度泛函理论和声子玻尔兹曼输运理论,研究了单层MoS_(2)的晶格热导率对温度的依赖关系,深入研究了单层MoS_(2)中声子的热输运机理。结果表明:单层MoS_(2)的晶格热导率在300K时为101.5W/(m·K),且热导率随温度的升高而降低。通过对比各声子支分析,得到单层MoS_(2)纵向声学支(LA)的群速度最大,且LA支占有单层MoS_(2)热导率的最大贡献率(46.47%)。最后计算了单层MoS_(2)的代表性声子平均自由程,发现当单层MoS_(2)的特征尺寸小于40.9nm时,可以通过改变纳米结构来有效地调节MoS_(2)的热导率。

The changeable regulation between lattice thermal conductivity of monolayer MoS_(2) and temperature was studied,and the thermal transport mechanism of phonons in monolayer MoS_(2) was investigated in depth based on the density functional theory and the phonon Boltzmann transport theory.The results showed that the lattice thermal conductivity of monolayer MoS_(2) was 101.5W/(m·K)at 300K,and it decreased with the increase of temperature.It was the largest for the group velocity of the longitudinal acoustic branch(LA)of monolayer MoS_(2) among all phonon branches,and the LA branch occupied the maximal contribution(46.47%)to the thermal conductivity of monolayer MoS_(2).The typical phone mean free path(MFP)of monolayer MoS_(2),which demonstrated that the thermal conductivity of MoS_(2) could be effectively regulated by changing the nanostructure while the characteristic size of monolayer MoS_(2) was less than 40.9 nm.