ABSTRACT

A thorough understanding of the microscopic picture of heat conduction in solids is critical to a broad range of applications, from thermal management of microelectronics to more efficient thermoelectric materials. The transport properties of phonons, the major microscopic heat carriers in semiconductors and insulators, particularly their scattering mechanisms, have been a central theme in microscale heat conduction research. In the past two decades, significant advancements have been made in computational and experimental efforts to probe phonon-phonon, phonon-impurity, and phonon-boundary scattering channels in detail. In contrast, electron-phonon scatterings were long thought to have negligible effects on thermal transport in most materials under ambient conditions. This article reviews the recent progress in first-principles computations and experimental methods that show clear evidence for a strong impact of electron-phonon interaction on phonon transport in a wide variety of technologically relevant solid-state materials. Under thermal equilibrium conditions, electron-phonon interactions can modify the total phonon scattering rates and renormalize the phonon frequency, as determined by the imaginary part and the real part of the phonon self-energy, respectively. Under nonequilibrium transport conditions, electron-phonon interactions can affect the coupled transport of electrons and phonons in the bulk through the “phonon/electron drag” mechanism as well as the interfacial thermal transport. Based on these recent results, we evaluate the potential use of electron-phonon interactions to control thermal transport in solids. We also provide an outlook on future directions of computational and experimental developments.

摘要

彻底了解固体中热传导的微观图像对于广泛的应用至关重要，从微电子的热管理到更高效的热电材料。声子的传输特性，半导体和绝缘体中的主要微观热载体，特别是它们的散射机制，一直是微尺度热传导研究的中心主题。在过去的二十年中，在详细探测声子-声子、声子-杂质和声子-边界散射通道方面的计算和实验工作取得了重大进展。相比之下，长期以来，人们一直认为电子-声子散射对环境条件下大多数材料的热传输的影响可以忽略不计。本文回顾了第一性原理计算和实验方法的最新进展，这些进展表明电子-声子相互作用对各种技术相关固态材料中的声子传输产生强烈影响的明确证据。在热平衡条件下，电子-声子相互作用可以修改总声子散射率并使声子频率重新归一化，分别由声子自能的虚部和实部决定。在非平衡传输条件下，电子-声子相互作用可以通过“声子/电子阻力”机制以及界面热传输影响体中电子和声子的耦合传输。根据这些最近的结果，我们评估了电子-声子相互作用在控制固体热传输方面的潜在用途。我们还提供了对未来计算和实验发展方向的展望。