原子レベルで観測された熱伝導の仕組み(How Heat Travels Across Materials: Now Seen at the Atomic Level)

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2025-06-20 北京大学(PKU)

原子レベルで観測された熱伝導の仕組み(How Heat Travels Across Materials: Now Seen at the Atomic Level)
Figure 1. Microscopy techniques for visualizing phonon transport.  a. Schematic diagram of the experimental design. b. Isotherm distribution (colored lines) and temperature gradient direction (black arrows) near the AlN/SiC interface. Scale bar: 200 nm.

北京大学・国際量子材料センターの高鵬研究チームは、電子顕微鏡による高速電子非弾性散乱を利用し、材料界面でのフォノン熱輸送を原子レベルで可視化する革新的技術を開発した。AlN/SiC接合において、2nmの範囲で10〜20Kの急激な温度変化を観測し、界面熱抵抗がバルク材の30〜70倍に達することを確認。また、3nm付近に非平衡フォノン状態を発見し、熱流の方向に応じたフォノン分布の変化を捉えた。本成果は、次世代半導体の熱管理やチップ設計に不可欠な界面熱輸送の理解を飛躍的に進展させるものである。

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電子顕微鏡による界面を横切るフォノン輸送ダイナミクスの研究 Probing phonon transport dynamics across an interface by electron microscopy

Fachen Liu,Ruilin Mao,Zhiqiang Liu,Jinlong Du & Peng Gao
Nature  Published:11 June 2025
DOI:https://doi.org/10.1038/s41586-025-09108-6

Abstract

Understanding thermal transport mechanisms across material interfaces is crucial for advancing semiconductor technologies, particularly in miniaturized devices operating under extreme power densities1,2. Although the interface phonon-mediated processes are theoretically established3,4,5,6 as the dominant mechanism for interfacial thermal transport in semiconductors7, their nanoscale dynamics remain experimentally elusive owing to challenges in measuring the temperature and non-equilibrium phonon distributions across the buried interface8,9,10,11. Here we overcome these limitations by using in situ vibrational electron energy-loss spectroscopy (EELS) in an electron microscope to nanoscale profile temperature gradients across the AlN–SiC interface during thermal transport and map its non-equilibrium phonon occupations at sub-nanometre resolution. We observe a sharp temperature drop within about 2 nm across the interface, enabling direct extraction of relative interfacial thermal resistance (ITR). During thermal transport, the mismatch of phonon modes’ thermal conductivity at the interface causes substantial non-equilibrium phonons nearby, making the populations of interface modes different under forward and reverse heat flow and also leading to marked changes in the modal temperature of AlN optical phonons within about 3 nm of the interface. These results reveal the phonon transport dynamics at the (sub-)nanoscale and establish the inelastic phonon scattering mechanism involved by interface modes, offering valuable insights into the engineering of thermal interfaces.

0105熱工学
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