Large tunability of lattice thermal conductivity of monolayer silicene via mechanical strain
Large tunability of lattice thermal conductivity of monolayer silicene via mechanical strain
复制标题
通过机械应变实现单层硅烯晶格热导率的大可调性
DOI：
10.1103/physrevb.93.075404
复制
发表时间：
2015-12
影响因子：
3.7
通讯作者：
Hua Bao
中科院分区：
文献类型：
--
作者：
Eric Germaneau;Guangzhao Qin;Ming Hu;Hua Bao
应变工程是最有前途和最有效的途径之一，不断调整材料的电子和光学性能，而热性能通常被认为是不敏感的机械应变。本文利用第一性原理计算得到的原子间力常数，通过求解声子玻尔兹曼输运方程，计算了均匀双轴拉伸下单层硅烯的应变相关热导率。与通常认为的导热率仅随着体材料的拉伸应变的增加而略微降低的理解不同，发现硅烯的导热率可以随着应变而显著增加。根据尺寸的不同，应变硅烯的最大热导率可以比未应变的情况高几倍。这种不寻常的应变依赖性主要归因于声学声子寿命的显着增强。这种增强可能源于硅烯结构在拉伸时的屈曲的平坦化，这与其他常见的二维材料相比对于硅烯是独特的。我们的研究结果提供了调制的应用，如热电，热电路和纳米电子学的低维结构的热性能的观点。
Strain engineering is one of the most promising and effective routes toward continuously tuning the electronic and optic properties of materials, while thermal properties are generally believed to be insensitive to mechanical strain. In this paper, the strain-dependent thermal conductivity of monolayer silicene under uniform biaxial tension is computed by solving the phonon Boltzmann transport equation with interatomic force constants extracted from first-principles calculations. Unlike the commonly believed understanding that thermal conductivity only slightly decreases with increased tensile strain for bulk materials, it is found that the thermal conductivity of silicene can increase dramatically with strain. Depending on the size, the maximum thermal conductivity of strained silicene can be a few times higher than that of the unstrained case. Such an unusual strain dependence is mainly attributed to the dramatic enhancement in the acoustic phonon lifetime. Such enhancement plausibly originates from the flattening of the buckling of the silicene structure upon stretching, which is unique for silicene as compared with other common two-dimensional materials. Our findings offer perspectives on modulating the thermal properties of low-dimensional structures for applications such as thermoelectrics, thermal circuits, and nanoelectronics.