表面共振圆环结构对Si纳米线热传导的调控

利用声子的波动性，在纳米线表面引入共振结构，可以有效阻碍声子输运.为进一步优化共振结构，本文基于平衡态分子动力学(EMD)方法，研究表面共振圆环结构的高度和宽度对Si纳米线热输运性质的影响.结果表明：随着共振圆环高度的增加，Si纳米线的热导率逐渐减小，最大减幅可达61.9%.当高度达到2nm以后，热导率基本不再变化.共振圆环宽度则对热导率的影响较小.声子色散关系中出现的平带，证实了共振圆环引起的声子共振效应；最低共振频率的变化说明了共振圆环中的声子波长决定了共振圆环高度对纳米线热导率的最大影响程度.研究进一步发现，随着共振圆环高度的增加，声学支声子对热导率贡献的比重变小.本文研究结果对高效热电材料和隔热材料的微纳结构设计提供了一种新的思路.

Regulation of thermal transport of Si nanowires by surface annulus phonon resonators

By using the wave nature of phonons, the resonance structure can be introduced on the surface of nanowires, which can effectively hinder the phonon propagation. In order to further optimize the resonant structure, based on the equilibrium molecular dynamics (EMD) method, this paper studies the influence of the height and width of the surface resonant annulus structure on the thermal transport of Si nanowires. The results show that with the increase of resonance annulus height, the thermal conductivity of Si nanowires decreases gradually until the height reaches 2nm, and the maximum reduction can reach 61.9%. The resonant annulus width has less effect on the thermal conductivity. The flat band in the acoustic branches in the dispersion relation confirms the phonon resonance effect caused by the resonance annulus, and the change of the minimum resonance frequency indicates that the phonon wavelength in the resonance annulus determines the maximum influence of the resonance annulus height on the nanowire thermal conductivity. We further found that with the increase of the resonance annulus height, acoustic phonons contribute less to the thermal conductivity. These results provide useful information for the structure design of high-efficiency thermoelectrics and thermal insulation materials.