硅纳米结构热输运的原子尺度模拟研究

Low dimensional thermoelectric materials, as green energy materials that have extensive application prospect, have attracted great attention.in recent years. It is key important for low dimensional nanomaterials to increase thermoelectric performance by decreasing the thermal conductivity. In this project, we use atomistic simulation method to calculate thermal conductivity of silicon nanostructures. We investigate the effect of stress on the thermal conductivity of Graphenelike silicon nanosheet (Silicene), in order to reveal physical mechanism of stress modulated thermal transport in Silicene. We also study the effect of surface chemical modification on the thermal conductivity of silicon nanowires. This study may serve as a highly useful experimental guide in enhancing the thermoelectric performance of silicon nanostructures via surface chemical modification.

低维热电材料作为一种具有广泛应用前景的绿色能源材料目前引起了极大关注. 设法降低热导率成为提高低维纳米材料热电性能的关键. 本课题采用原子尺度模拟方法计算硅纳米结构的热导率，研究应力对类石墨烯硅纳米阵列（Silicene）热导率的影响，揭示应力调制Silicene热输运的物理机制；研究表面化学修饰对硅纳米线热输运的影响，为实验上通过表面修饰提高硅纳米结构的热电性能提供有益指导.

采用分子动力学模拟方法，我们计算了硅纳米线和氢原子钝化硅纳米线的结构、声子热导率和声子态密度。我们研究了硅纳米线热导率的尺度效应和表面钝化效应。结果表明：随着硅纳米线截面面积的增大，体系的声子热导率也增大。相对于没有表面钝化的硅纳米线，氢钝化能够稍微增加声子热导率。我们从表面氢钝化对硅纳米线的结构和声子谱的影响角度解释了氢钝化硅增加纳米线热导率的原因。该研究对于表面调控硅纳米线热导率提供了理论支持，对硅纳米线热电材料的研究也具有重要的学术价值。