Quantifying Surface Roughness Effects on Phonon Transport in Silicon Nanowires

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• 作者：Jongwoo Lim ; Kedar Hippalgaonkar ; Sean C. Andrews ; Arun Majumdar ; Peidong Yang
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：May 9, 2012
• 年：2012
• 卷：12
• 期：5
• 页码：2475-2482
• 全文大小：510K
• 年卷期：v.12,no.5(May 9, 2012)
• ISSN：1530-6992

文摘

Although it has been qualitatively demonstrated that surface roughness can reduce the thermal conductivity of crystalline Si nanowires (SiNWs), the underlying reasons remain unknown and warrant quantitative studies and analysis. In this work, vapor鈥搇iquid鈥搒olid (VLS) grown SiNWs were controllably roughened and then thoroughly characterized with transmission electron microscopy to obtain detailed surface profiles. Once the roughness information (root-mean-square, 蟽, correlation length, L, and power spectra) was extracted from the surface profile of a specific SiNW, the thermal conductivity of the same SiNW was measured. The thermal conductivity correlated well with the power spectra of surface roughness, which varies as a power law in the 1鈥?00 nm length scale range. These results suggest a new realm of phonon scattering from rough interfaces, which restricts phonon transport below the Casimir limit. Insights gained from this study can help develop a more concrete theoretical understanding of phonon鈥搒urface roughness interactions as well as aid the design of next generation thermoelectric devices.

Keywords:

Nanowire; silicon; roughness; thermoelectrics; thermal conductivity; phonons