Shape and Orientation Effects on the Ballistic Phonon Thermal Properties of Ultra-Scaled Si Nanowires

Abhijeet Paul, Purdue University
Mathieu Luisier, Purdue University
Gerhard Klimeck, Purdue University

Date of this Version



Journal of Applied Physics: Volume 110, Issue 11. doi: 10.1063/1.3662177


Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics: Volume 110, Issue 11 and may be found at The following article has been submitted to/accepted by Journal of Applied Physics. Copyright (2011) Abhijeet Paul, Mathieu Luisier, and Gerhard Klimeck. This article is distributed under a Creative Commons Attribution 3.0 Unported License.


The effect of geometrical confinement, atomic position and orientation of Silicon nanowires (SiNWs) on their thermal properties are investigated using the phonon dispersion obtained using a Modified Valence Force Field (MVFF) model. The spe- cific heat (Cv) and the ballistic thermal conductance (κbal) shows anisotropic variation l with changing cross-section shape and size of the SiNWs. The Cv increases with de- creasing cross-section size for all the wires. The triangular wires show the largest Cv due to their highest surface-to-volume ratio. The square wires with [110] orientation show the maximum κbal since they have the highest number of conducting phonon l modes. At the nano-scale a universal scaling law for both Cv and κbal are obtained l with respect to the number of atoms in the unit cell. This scaling is independent of the shape, size and orientation of the SiNWs revealing a direct correlation of the lattice thermal properties to the atomistic properties of the nanowires. Thus, en- gineering the SiNW cross-section shape, size and orientation open up new ways of tuning the thermal properties at the nanometer regime.


Nanoscience and Nanotechnology