Department of Chemistry, University of California, Davis, California 95616, United States.
ACS Nano. 2011 Mar 22;5(3):1839-44. doi: 10.1021/nn2003184. Epub 2011 Feb 10.
We present molecular and lattice dynamics calculations of the thermal conductivity of nanoporous silicon, and we show that it may attain values 10-20 times smaller than in bulk Si for porosities and surface-to-volume ratios similar to those obtained in recently fabricated nanomeshes. Further reduction of almost an order of magnitude is obtained in thin films with thickness of 20 nm, in agreement with experiment. We show that the presence of pores has two main effects on heat carriers: appearance of non-propagating, diffusive modes and reduction of the group velocity of propagating modes. The former effect is enhanced by the presence of disorder at the pore surfaces, while the latter is enhanced by decreasing film thickness.
我们提出了纳米多孔硅热导率的分子和晶格动力学计算，结果表明，对于与最近制造的纳米网类似的孔隙率和表面积与体积比，其热导率可能比体硅小 10-20 倍。在厚度为 20nm 的薄膜中，我们得到了几乎一个数量级的进一步降低，这与实验结果一致。我们表明，孔隙的存在对热载体有两个主要影响：出现非传播、扩散模式和传播模式的群速度降低。前者的影响因孔隙表面的无序而增强，而后者则因薄膜厚度的减小而增强。
