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arXiv · 2106.10922

Matryoshka Phonon Twinning in alpha-GaN

Bin Wei·Qingan Cai·Qiyang Sun·Yaokun Su·Ayman H. Said·Douglas L. Abernathy·Jiawang Hong·Chen Li
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Abstract

Understanding lattice dynamics is crucial for effective thermal management in high-power electronic devices because phonons dominate thermal transport in most semiconductors. This study utilizes complementary inelastic X-ray and neutron scattering techniques and reports the temperature-dependent phonon dynamics of alpha-GaN, one of the most important third-generation power semiconductors. A prominent Matryoshka phonon dispersion is discovered with the scattering tools and confirmed by the first-principles calculations. Such Matryoshka twinning throughout the three-dimension reciprocal space is demonstrated to amplify the anharmonicity of the related phonon modes through creating abundant three-phonon scattering channels and cutting the phonon lifetime of affected modes by more than 50%. Such phonon topology effectively contributes to the reduction of the in-plane thermal transport, thus the anisotropic thermal conductivity of alpha-GaN. The results not only have significant implications for engineering the thermal performance and other phonon-related properties of alpha-GaN, but also offer valuable insights on the role of anomalous phonon topology in thermal transport of other technically important semiconductors.

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Bin Wei, Qingan Cai, Qiyang Sun, Yaokun Su, Ayman H. Said, Douglas L. Abernathy, Jiawang Hong, Chen Li. 2021-06-21. Matryoshka Phonon Twinning in alpha-GaN. https://doi.org/10.1038/s42005-021-00727-9

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