Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan.
Laboratory for Integrated Micro Mechatronic Systems/National Center for Scientific Research-Institute of Industrial Science (LIMMS/CNRS-IIS), The University of Tokyo, Tokyo 153-8505, Japan.
Sci Rep. 2017 Feb 2;7:41794. doi: 10.1038/srep41794.
We have experimentally investigated the impact of dimensions and temperature on the thermal conductivity of silicon nanowires fabricated using a top-down approach. Both the width and temperature dependences of thermal conductivity agree with those in the existing literature. The length dependence of thermal conductivity exhibits a transition from semi-ballistic thermal phonon transport at 4 K to fully diffusive transport at room temperature. We additionally calculated the phonon dispersion in these structures in the framework of the theory of elasticity and showed that the thermal conductance increases with width. This agrees with our experimental observations and supports the pertinence of using the modified phonon dispersion at low temperatures.
我们通过实验研究了自上而下法制备的硅纳米线的尺寸和温度对热导率的影响。热导率的宽度和温度依赖性与现有文献中的结果一致。热导率的长度依赖性表现出从 4 K 时的半弹道热声子输运到室温时的完全扩散输运的转变。我们还在弹性理论的框架内计算了这些结构中的声子色散，并表明热导与宽度成正比。这与我们的实验观察结果一致，并支持在低温下使用修正的声子色散的合理性。
