Zhou Jiawei, Shin Hyun D, Chen Ke, Song Bai, Duncan Ryan A, Xu Qian, Maznev Alexei A, Nelson Keith A, Chen Gang
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Nat Commun. 2020 Nov 27;11(1):6040. doi: 10.1038/s41467-020-19938-9.
As a foundational concept in many-body physics, electron-phonon interaction is essential to understanding and manipulating charge and energy flow in various electronic, photonic, and energy conversion devices. While much progress has been made in uncovering how phonons affect electron dynamics, it remains a challenge to directly observe the impact of electrons on phonon transport, especially at environmental temperatures. Here, we probe the effect of charge carriers on phonon heat transport at room temperature, using a modified transient thermal grating technique. By optically exciting electron-hole pairs in a crystalline silicon membrane, we single out the effect of the phonon-carrier interaction. The enhanced phonon scattering by photoexcited free carriers results in a substantial reduction in thermal conductivity on a nanosecond timescale. Our study provides direct experimental evidence of the elusive role of electron-phonon interaction in phonon heat transport, which is important for understanding heat conduction in doped semiconductors. We also highlight the possibility of using light to dynamically control thermal transport via electron-phonon coupling.
作为多体物理学中的一个基础概念，电子 - 声子相互作用对于理解和操控各种电子、光子及能量转换器件中的电荷和能量流动至关重要。尽管在揭示声子如何影响电子动力学方面已取得了很大进展，但直接观察电子对声子输运的影响仍然是一项挑战，尤其是在环境温度下。在此，我们使用一种改进的瞬态热光栅技术，探究了室温下电荷载流子对声子热输运的影响。通过在晶体硅膜中光激发电子 - 空穴对，我们分离出声子 - 载流子相互作用的影响。光激发的自由载流子增强的声子散射导致在纳秒时间尺度上热导率大幅降低。我们的研究为电子 - 声子相互作用在声子热输运中难以捉摸的作用提供了直接实验证据，这对于理解掺杂半导体中的热传导很重要。我们还强调了利用光通过电子 - 声子耦合动态控制热输运的可能性。
