Lattice thermal conduction in ultra-thin nanocomposites
Lattice thermal conduction in ultra-thin nanocomposites
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DOI：
10.1063/1.4954678
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发表时间：
2016-06
影响因子：
3.2
通讯作者：
I. O. Thomas;G. P. Srivastava
中科院分区：
文献类型：
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作者：
I. O. Thomas;G. P. Srivastava
我们研究了Si/Ge周期性纳米复合材料（超晶格、纳米线和纳米点结构）的晶格热导率，样品尺寸在30 nm-30 μm范围内，周期为1.1 nm和2.2 nm，界面相当脏，n型掺杂浓度在1023-1026 m−3范围内。我们的计算采用了一个明智的从头算和物理健全的半经验方法的详细计算由于非谐性和界面形成的声子散射率的估计相结合。根据我们的研究结果，我们得出结论，超薄纳米复合材料的形成在任何三种结构是能够降低合金极限以下的导电性。这可以解释为样品长度的依赖性的组合的结果，在设置的mini-Umklapp三声子过程，质量混合在Si和Ge区域之间的界面，和样品掺杂水平。
We have studied the lattice thermal conductivity of Si/Ge periodic nanocomposites (superlattice, nanowire, and nanodot structures) of sample sizes in the range of 30 nm–30 μm, periodicities 1.1 nm and 2.2 nm, with reasonably dirty interfaces, and n-type doping concentration in the range of 1023–1026 m−3. Our calculations employ a judicious combination of ab initio and physically sound semi-empirical methods for detailed calculations of estimates of phonon scattering rates due to anharmonicity and interface formation. Based upon our results we conclude that the formation of ultra-thin nanocomposites in any of the three structures is capable of reducing the conductivity below the alloy limit. This can be explained as a result of combination of the sample length dependence, the on-set of mini-Umklapp three-phonon processes, mass mixing at the interfaces between Si and Ge regions, and the sample doping level.