论文标题
基于第一原理的金属纳米结构中的热传输分析：尺寸效应和Wiedemann-Franz定律
First-principles based analysis of thermal transport in metallic nanostructures: size effect and Wiedemann-Franz law
论文作者
论文摘要
金属纳米结构（纳米膜和纳米线）被广泛用于电子设备，其热传输特性对于散热至关重要。但是，了解金属纳米结构中的热运输仍然存在差距，尤其是关于Wiedemann-Franz定律的尺寸效应和有效性。在这项工作中，我们执行模式的第一原理计算，结合了Boltzmann传输方程，以了解金属纳米结构中的热传输。我们将黄金（AU）和钨（W）纳米结构作为原型。发现当纳米结构的大小处于几十纳米的顺序时，电子/声子导电率小于大量值，并且随大小而降低。对于那些具有较小的散装声子导热率（如AU）的金属的纳米结构中的声子贡献增加，而声子的贡献可能会增加或抑制那些具有较大散装声子导热率的金属（如W）的纳米结构中。通过假设晶界不会诱导非弹性电子 - 音波散射，如果使用电子导热率估算Lorentz的比率，则Wiedemann-Franz定律在AU和W纳米结构中都很好地工作。当洛伦兹（Lorentz）比例通过总导热率估算时，Wiedemann-Franz定律在AU纳米结构中也很好地工作。
Metallic nanostructures (the nanofilms and nanowires) are widely used in electronic devices, and their thermal transport properties are crucial for heat dissipation. However, there are still gaps in understanding thermal transport in metallic nanostructures, especially regarding the size effect and validity of the Wiedemann-Franz law. In this work, we perform mode-by-mode first-principles calculations combining the Boltzmann transport equation to understand thermal transport in metallic nanostructures. We take the gold (Au) and tungsten (W) nanostructures as prototypes. It is found that when the size of nanostructures is on the order of several tens of nanometers, the electronic/phonon thermal conductivity is smaller than the bulk value and decreases with size. The phonon contribution increases in nanostructures for those metals with small bulk phonon thermal conductivity (like Au), while the phonon contribution may increase or be suppressed in nanostructures for those metals with large bulk phonon thermal conductivity (like W). By assuming that the grain boundary does not induce inelastic electron-phonon scattering, the Wiedemann-Franz law works well in both Au and W nanostructures if the Lorentz ratio is estimated using electronic thermal conductivity. The Wiedemann-Franz law also works well in Au nanostructures when the Lorentz ratio is estimated by total thermal conductivity.
