Yao Fengju, Xia Shunji, Wei Haoxiang, Zheng Jiongzhi, Yuan Ziyuan, Wang Yusheng, Huang Baoling, Li Deyu, Lu Hong, Xu Dongyan
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region 999077, China.
National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China.
Nano Lett. 2022 Sep 14;22(17):6888-6894. doi: 10.1021/acs.nanolett.2c01050. Epub 2022 Sep 2.
Superdiffusive thermal transport represents a unique phenomenon in heat conduction, which is characterized by a size () dependence of thermal conductivity (κ) in the form of κ ∝ with a constant β between 0 and 1. Although superdiffusive thermal transport has been theoretically predicted for SiGe alloys, direct experimental evidence is still lacking. Here, we report on a systematic experimental study of the thickness-dependent thermal conductivity of SiGe thin films grown by molecular beam epitaxy. The cross-plane thermal conductivity of SiGe thin films spanning a thickness range from 20 to 1120 nm was measured in the temperature range 120-320 K via a differential three-omega method. Results show that the thermal conductivity follows a consistent κ ∝ power law with the film thickness () at different temperatures, providing direct experimental evidence that alloy-scattering dominated thermal transport in SiGe is superdiffusive.
超扩散热输运是热传导中一种独特的现象，其特征在于热导率（κ）与尺寸（）呈κ ∝ 的依赖关系，其中常数β在0到1之间。尽管理论上已预测硅锗合金存在超扩散热输运，但仍缺乏直接的实验证据。在此，我们报告了一项关于分子束外延生长的硅锗薄膜厚度依赖性热导率的系统实验研究。通过差分三ω法在120 - 320 K的温度范围内测量了厚度范围为20至1120 nm的硅锗薄膜的面内热导率。结果表明，在不同温度下，热导率与薄膜厚度（）遵循一致的κ ∝ 幂律，提供了直接的实验证据，证明硅锗中合金散射主导的热输运是超扩散的。
