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Phonon transport in the nano-system of Si and SiGe films with Ge nanodots and approach to ultralow thermal conductivity
Nanoscale ( IF 5.8 ) Pub Date : 2021-2-25 , DOI: 10.1039/d0nr08499a
Tatsuhiko Taniguchi 1, 2, 3, 4 , Tsukasa Terada 1, 2, 3, 4 , Yuki Komatsubara 1, 2, 3, 4 , Takafumi Ishibe 1, 2, 3, 4 , Kento Konoike 1, 2, 3, 4 , Atsushi Sanada 1, 2, 3, 4 , Nobuyasu Naruse 4, 5, 6, 7 , Yutaka Mera 4, 5, 6, 7 , Yoshiaki Nakamura 1, 2, 3, 4
Affiliation  

Phonon transport in the nano-system has been studied using well-designed nanostructured materials to observe and control the interesting phonon behaviors like ballistic phonon transport. Recently, we observed drastic thermal conductivity reduction in the films containing well-controlled nanodots. Here, we investigate whether this comes from the interference effect in ballistic phonon transport by comparing the thermal properties of the Si or Si0.75Ge0.25 films containing Ge nanodots. The experimentally-obtained thermal resistance of the nanodot layer shows peculiar nanodot size dependence in the Si films and a constant value in the SiGe films. From the phonon simulation results, interestingly, it is clearly found that in the nanostructured Si film, phonons travel in a non-diffusive way (ballistic phonon transport). On the other hand, in the nanostructured SiGe film, although simple diffusive phonon transport occurs, extremely-low thermal conductivity (∼0.81 W m−1 K−1) close to that of amorphous Si0.7Ge0.3 (∼0.7 W m−1 K−1) is achieved due to the combination of the alloy phonon scattering and Ge nanodot scattering.

中文翻译:

具有Ge纳米点的Si和SiGe薄膜纳米系统中的声子传输及其超低导热性的方法

已经使用精心设计的纳米结构材料研究了纳米系统中的声子传输,以观察和控制有趣的声子行为,例如弹道声子传输。最近,我们观察到含有良好控制的纳米点的薄膜的热导率急剧降低。在这里,我们通过比较Si或Si 0.75 Ge 0.25的热性质,研究这是否来自弹道声子传输中的干扰效应。含有Ge纳米点的薄膜。实验获得的纳米点层的热阻在Si膜中显示出特殊的纳米点尺寸依赖性,而在SiGe膜中显示出恒定值。有趣的是,从声子模拟结果可以清楚地发现,在纳米结构的Si膜中,声子以非扩散方式传播(弹道声子传输)。另一方面,在纳米结构的SiGe膜中,尽管发生了简单的扩散声子传输,但是极低的热导率(〜0.81 W m -1 K -1)接近非晶硅0.7 Ge 0.3(〜0.7 W m -1)由于合金声子散射和Ge纳米点散射的组合而获得了K -1)。
更新日期:2021-02-25
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