Thermal conductivity of silicon nanowire arrays with controlled roughness
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Fang_Thermal conductivity.pdf
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Author(s)
Feser, Joseph P.
Sadhu, Jyothi S.
Azeredo, Bruno P.
Hsu, Keng H.
Ma, Jun
Kim, Junhwan
Seong, Myunghoon
Fang, Nicholas Xuanlai
Li, Xiuling
Ferreira, Placid M.
Date Issued
December 2012
Journal
Journal of Applied Physics
Publisher
American Institute of Physics (AIP)
Citation
Feser, Joseph P., Jyothi S. Sadhu, Bruno P. Azeredo, et al. Thermal Conductivity of Silicon Nanowire Arrays with Controlled Roughness. Journal of Applied Physics 112(11): 114306, 2012. © 2012 American Institute of Physics
Version
Final published version
Abstract
A two-step metal assisted chemical etching technique is used to systematically vary the sidewall roughness of Si nanowires in vertically aligned arrays. The thermal conductivities of nanowire arrays are studied using time domain thermoreflectance and compared to their high-resolution transmission electron microscopy determined roughness. The thermal conductivity of nanowires with small roughness is close to a theoretical prediction based on an upper limit of the mean-free-paths of phonons given by the nanowire diameter. The thermal conductivity of nanowires with large roughness is found to be significantly below this prediction. Raman spectroscopy reveals that nanowires with large roughness also display significant broadening of the one-phonon peak; the broadening correlates well with the reduction in thermal conductivity. The origin of this broadening is not yet understood, as it is inconsistent with phonon confinement models, but could derive from microstructural changes that affect both the optical phonons observed in Raman scattering and the acoustic phonons that are important for heat conduction.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1063/1.4767456
