Heat Conductance Is Strongly Anisotropic for Pristine Silicon Nanowires
- 24 September 2008
- journal article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 8 (11), 3771-3775
- https://doi.org/10.1021/nl8020889
Abstract
We compute atomistically the heat conductance for ultrathin pristine silicon nanowires (SiNWs) with diameters ranging from 1 to 5 nm. The room temperature thermal conductance is found to be highly anisotropic: wires oriented along the ⟨110⟩ direction have 50−75% larger conductance than wires oriented along the ⟨100⟩ and ⟨111⟩ directions. We show that the anisotropies can be qualitatively understood and reproduced from the bulk phonon band structure. Ab initio density functional theory (DFT) is used to study the thinnest wires, but becomes computationally prohibitive for larger diameters, where we instead use the Tersoff empirical potential model (TEP). For the smallest wires, the thermal conductances obtained from DFT and TEP calculations agree within 10%. The presented results could be relevant for future phonon-engineering of nanowire devices.Keywords
This publication has 36 references indexed in Scilit:
- Silicon nanowires as efficient thermoelectric materialsNature, 2008
- Enhanced thermoelectric performance of rough silicon nanowiresNature, 2008
- Confined Phonons in Si NanowiresNano Letters, 2005
- Controlled Growth and Structures of Molecular-Scale Silicon NanowiresNano Letters, 2004
- Thermal conductivity of individual silicon nanowiresApplied Physics Letters, 2003
- Calculation of Si nanowire thermal conductivity using complete phonon dispersion relationsPhysical Review B, 2003
- Small-Diameter Silicon Nanowire SurfacesScience, 2003
- Effect of Phonon Scattering by Surface Roughness on the Universal Thermal ConductancePhysical Review Letters, 2001
- Phonon heat conduction in a semiconductor nanowireJournal of Applied Physics, 2001
- Control of Thickness and Orientation of Solution-Grown Silicon NanowiresScience, 2000