论文标题
超薄SI纳米线中的热传输：第一原理研究
Thermal transport in ultrathin Si nanowires: a first principles study
论文作者
论文摘要
已经使用密度函数扰动理论分析了[110]方向上小Si纳米线的声子特性。已经计算了几个直径范围为0.38至1.5 nm的样品。发现区域中心的光子声子的频率往往随着纳米线大小的增加而降低。对声子散射率的研究表明，最小的样品值非常高，随着纳米线大小的增加而降低。显示直径从0.53和0.78 nm增加到0.86 nm的散射速率发生了显着变化。较高的声子散射可以归因于特定频率的声子模式的对齐。相对于散装Si，导热率的结果较低，发现15至102 W/MK。可以观察到随着直径增加而增加导热率的趋势。这种效果归因于声子分散的几个变化，这些变化不一定与电线尺寸相关。当边界效应与Casimir散射近似时，这些显式结果已与热导率进行了比较。 Casimir方法显着低估了显式纳米线的结果。
Phonon properties of small Si nanowires in [110] direction have been analyzed using density functional perturbation theory. Several samples with varying diameters ranging from 0.38 to 1.5 nm have been calculated. It is found that the frequency of optical phonons at the zone center tend to decrease with increasing size of the nanowire. Investigation of the phonon scattering rates has revealed very high values in the smallest sample which decrease with increasing nanowire size. A remarkable change in scattering rates is shown for increasing diameter from 0.53 and 0.78 nm to 0.86 nm. The higher phonon scattering could be attributed to an alignment of phonon modes at a specific frequency. Results of the thermal conductivity are lower with respect to bulk Si and are found between 15 and 102 W/mK. A trend of increasing thermal conductivity with increasing diameter can be observed. This effect is attributed to several changes in the phonon dispersion which are not necessarily correlated to the wire size. These explicit results have been compared to the thermal conductivity when boundary effect is approximated with Casimir scattering. The Casimir method substantially underestimates the results for explicit nanowires.
