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Quantifying surface roughness effects on phonon transport in silicon nanowires
Jongwoo Lim1, Kedar Hippalgaonkar, Sean C Andrews
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Nano Letters
|April 25, 2012
Summary
Surface roughness in silicon nanowires (SiNWs) significantly impacts thermal conductivity. This study quantifies this effect, revealing a correlation between surface roughness spectra and reduced thermal conductivity, guiding thermoelectric device design.
Area of Science:
- Materials Science
- Nanotechnology
- Condensed Matter Physics
Background:
- Surface roughness is known to affect the thermal conductivity of crystalline silicon nanowires (SiNWs).
- Quantitative understanding of the underlying mechanisms remains limited.
Purpose of the Study:
- To quantitatively investigate the relationship between surface roughness and thermal conductivity in SiNWs.
- To analyze the impact of specific roughness parameters on phonon transport.
Main Methods:
- Controlled roughening of vapor-liquid-solid (VLS) grown SiNWs.
- Characterization using transmission electron microscopy (TEM) to obtain surface profiles.
- Measurement of thermal conductivity on the same SiNWs after roughness analysis.
Main Results:
- Detailed surface profiles yielded roughness parameters (σ, L, power spectra).
- Thermal conductivity showed a strong correlation with the power spectra of surface roughness.
- Roughness power spectra followed a power law across the 1-100 nm length scale.
Conclusions:
- Phonon scattering at rough interfaces is a significant factor limiting thermal transport, potentially below the Casimir limit.
- Findings contribute to a better theoretical understanding of phonon-surface roughness interactions.
- This research aids in designing advanced thermoelectric devices.
