Effects of Localized Interface Phonons on Heat Conductivity in Ingredient Heterogeneous Solids
Mei Wu1,2†, Ruochen Shi1,2†, Ruishi Qi1,2,3†, Yuehui Li1,2, Tao Feng4,5, Bingyao Liu2, Jingyuan Yan2, Xiaomei Li1,2, Zhetong Liu2, Tao Wang2, Tongbo Wei4,5, Zhiqiang Liu4,5, Jinlong Du2, Ji Chen6,7, and Peng Gao1,2,7,8,9*
1International Center for Quantum Materials, Peking University, Beijing 100871, China 2Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China 3Department of Physics, University of California at Berkeley, Berkeley 94720, USA 4Research and Development Center for Semiconductor Lighting Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China 5Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China 6State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China 7Collaborative Innovation Center of Quantum Matter, Beijing 100871, China 8Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China 9Hefei National Laboratory, Hefei 230088, China
Abstract：Phonons are the primary heat carriers in non-metallic solids. In compositionally heterogeneous materials, the thermal properties are believed to be mainly governed by the disrupted phonon transport due to mass disorder and strain fluctuations, while the effects of compositional fluctuation induced local phonon states are usually ignored. Here, by scanning transmission electron microscopy electron energy loss spectroscopy and sophisticated calculations, we identify the vibrational properties of ingredient-dependent interface phonon modes in Al$_{x}$Ga$_{1-x}$N and quantify their various contributions to the local interface thermal conductance. We demonstrate that atomic-scale compositional fluctuation has significant influence on the vibrational thermodynamic properties, highly affecting the mode ratio and vibrational amplitude of interface phonon modes and subsequently redistributing their modal contribution to the interface thermal conductance. Our work provides fundamental insights into understanding of local phonon-boundary interactions in nanoscale inhomogeneities, which reveal new opportunities for optimization of thermal properties via engineering ingredient distribution.
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2023, Vol. 40 
