Suppressed thermal transport in silicon nanoribbons by inhomogeneous strain

• 成果类型: Article
• 署名作者: Yang, Lin; Yue, Shengying; Tao, Yi; Qiao, Shuo; Li, Hang; Dai, Zhaohe; Song, Bai; Chen, Yunfei; Du, Jinlong; Li, Deyu; Gao, Peng
• 署名单位: Peking University; Xi'an Jiaotong University; Southeast University - China; Southeast University - China; Peking University; Peking University; Peking University; Vanderbilt University; Peking University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5917
• DOI: 10.1038/s41586-024-07390-4
• 发表日期: 2024-05-30
• 页码: 1021-+
• 关键词: total-energy calculations; carrier mobility; point-defects; conductivity; approximation; spectroscopy; SCATTERING; phonons

摘要

Nanoscale structures can produce extreme strain that enables unprecedented material properties, such as tailored electronic bandgap(1-5), elevated superconducting temperature(6,7) and enhanced electrocatalytic activity(8,9). While uniform strains are known to elicit limited effects on heat flow(10-15), the impact of inhomogeneous strains has remained elusive owing to the coexistence of interfaces(16-20) and defects(21-23). Here we address this gap by introducing inhomogeneous strain through bending individual silicon nanoribbons on a custom-fabricated microdevice and measuring its effect on thermal transport while characterizing the strain-dependent vibrational spectra with sub-nanometre resolution. Our results show that a strain gradient of 0.112% per nanometre could lead to a drastic thermal conductivity reduction of 34 +/- 5%, in clear contrast to the nearly constant values measured under uniform strains(10,12,14,15). We further map the local lattice vibrational spectra using electron energy-loss spectroscopy, which reveals phonon peak shifts of several millielectron-volts along the strain gradient. This unique phonon spectra broadening effect intensifies phonon scattering and substantially impedes thermal transport, as evidenced by first-principles calculations. Our work uncovers a crucial piece of the long-standing puzzle of lattice dynamics under inhomogeneous strain, which is absent under uniform strain and eludes conventional understanding.