Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zürich, Switzerland.
Integrated Systems Laboratory, ETH Zurich , Gloriastrasse 35, 8092 Zürich, Switzerland.
Nano Lett. 2017 Jan 11;17(1):276-283. doi: 10.1021/acs.nanolett.6b04050. Epub 2017 Jan 3.
Recent experimental advances have revealed that the mean free path (mfp) of phonons contributing significantly to thermal transport in crystalline semiconductors can be several microns long. Almost all of these experiments are based on bulk and thin film materials and use techniques that are not directly applicable to nanowires. By developing a process with which we could fabricate multiple electrically contacted and suspended segments on individual heavily doped smooth Silicon nanowires, we measured phonon transport across varying length scales using a DC self-heating technique. Our measurements show that diffusive thermal transport is still valid across O(100) nm length scales, supporting the diffuse nature of phonon-boundary scattering even on smooth nanowire surfaces. Our work also showcases the self-heating technique as an important alternative to the thermal bridge technique to measure phonon transport across short length scales relevant to mapping the phonon mfp spectrum in nanowires.
最近的实验进展表明，对晶态半导体中热输运有重要贡献的声子的平均自由程（mfp）可以长达数微米。几乎所有这些实验都是基于体材料和薄膜材料进行的，并且使用的技术不能直接应用于纳米线。通过开发一种工艺，我们可以在单个重掺杂的光滑硅纳米线上制造多个电接触和悬置段，我们使用直流自加热技术测量了跨越不同长度尺度的声子输运。我们的测量结果表明，在 O(100)nm 的长度尺度上，扩散热输运仍然有效，这支持了即使在光滑纳米线表面上，声子-边界散射的弥散性质。我们的工作还展示了自加热技术作为一种替代热桥技术的重要方法，可用于测量与在纳米线中映射声子 mfp 谱相关的短长度尺度上的声子输运。
