Surface phonons limit heat conduction in thin films
Surface phonons limit heat conduction in thin films
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表面声子限制了薄膜中的热传导
DOI：
10.1103/physrevb.103.195418
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发表时间：
2020-08
影响因子：
3.7
通讯作者：
M. Morita;T. Shiga
中科院分区：
文献类型：
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作者：
M. Morita;T. Shiga
了解薄型fi液晶显示系统的微观热传导特性，对于纳米/微米传热学和先进电子设备的热管理具有重要意义。当fi薄膜的厚度与声子波长相当或小于一个声子波长时，声子的色散关系和输运性质被显著地调制，这在薄fi薄膜的热传导中是必须考虑的。虽然考虑了声子的掺杂和耗尽等因素，但应该强调的是，表面局域声子(表面声子)的产生对热传导的影响是不可忽略的，因为它具有很高的表面积体积比(fl/体积比)。然而，到目前为止，表面声子在热传导中的作用还没有引起足够的重视。在本工作中，我们用非简谐晶格动力学方法从表面声子的角度研究了厚度小于10 nm的硅薄膜fi的面内导热系数与厚度和温度的关系。通过对表面声子强度的系统分析，我们发现薄fl中表面声子和内部声子之间的非简谐耦合显著地抑制了薄fifi中的整体面内热传导。我们还发现fic的低频表面声子对表面-内部声子散射和热传导抑制有显著的贡献。我们的fi结有利于电子和声子器件的热管理，并可能导致用于热导控制的表面声子工程。
Understanding microscopic heat conduction in thin films is important for nano/micro heat transfer and thermal management for advanced electronics. As the thickness of thin films is comparable to or shorter than a phonon wavelength, phonon dispersion relations and transport properties are significantly modulated, which should be taken into account for heat conduction in thin films. Although phonon confinement and depletion effects have been considered, it should be emphasized that surface-localized phonons (surface phonons) arise whose influence on heat conduction may not be negligible due to the high surface-to-volume ratio. However, the role of surface phonons in heat conduction has received little attention thus far. In the present work, we performed anharmonic lattice dynamics calculations to investigate the thickness and temperature dependence of in-plane thermal conductivity of silicon thin films with sub-10-nm thickness in terms of surface phonons. Through systematic analysis of the influences of surface phonons, we found that anharmonic coupling between surface and internal phonons localized in thin films significantly suppresses overall in-plane heat conduction in thin films. We also discovered that specific low-frequency surface phonons significantly contribute to surface–internal phonon scattering and heat conduction suppression. Our findings are beneficial for the thermal management of electronics and phononic devices and may lead to surface phonon engineering for thermal conductivity control.