Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542, Singapore.
J Chem Phys. 2011 Nov 28;135(20):204705. doi: 10.1063/1.3663386.
By using molecular dynamics simulations, we study thermal conductivity of silicon nanowires (SiNWs) with different cross sectional geometries. It is found that thermal conductivity decreases monotonically with the increase of surface-to-volume ratio (SVR). More interestingly, a simple universal linear dependence of thermal conductivity on SVR is observed for SiNWs with modest cross sectional area (larger than 20 nm(2)), regardless of the cross sectional geometry. As a result, among different shaped SiNWs with the same cross sectional area, the one with triangular cross section has the lowest thermal conductivity. Our study provides not only a universal gauge for thermal conductivity among different cross sectional geometries, but also a designing guidance to tune thermal conductivity by geometry.
利用分子动力学模拟，我们研究了不同横截面几何形状的硅纳米线（SiNWs）的热导率。结果发现，热导率随比表面积比（SVR）的增加而单调下降。更有趣的是，对于具有中等横截面面积（大于 20nm^2）的 SiNWs，无论其横截面几何形状如何，都观察到热导率与 SVR 之间存在简单的通用线性关系。因此，在具有相同横截面面积的不同形状的 SiNWs 中，具有三角形横截面的 SiNWs 具有最低的热导率。我们的研究不仅为不同横截面几何形状之间的热导率提供了通用的衡量标准，而且还为通过几何形状来调节热导率提供了设计指导。
