Open Access Nano Express

Thermal conductance calculations of silicon nanowires: comparison with diamond nanowires

Kohei Yamamoto1*, Hiroyuki Ishii1, Nobuhiko Kobayashi1 and Kenji Hirose2

Author Affiliations

1 Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan

2 Green Innovation Research Laboratory, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan

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Nanoscale Research Letters 2013, 8:256  doi:10.1186/1556-276X-8-256

Published: 29 May 2013

Abstract

We present phonon thermal conductance calculations for silicon nanowires (SiNWs) with diameters ranging from 1 to 5 nm with and without vacancy defects by the non-equilibrium Green’s function technique using the interatomic Tersoff-Brenner potentials. For the comparison, we also present phonon thermal conductance calculations for diamond nanowires. For two types of vacancy defects in the SiNW, a ‘center defect’ and a ‘surface defect’, we found that a center-defect reduces thermal conductance much more than a surface defect. We also found that the thermal conductance changes its character from the usual behavior, in proportion to the square of diameter (the cross-sectional area) for over 100 and 300 K, to the unusual one, not dependent on its diameter at all at low temperature. The crossover is attributed to the quantization of thermal conductance.

Keywords:
Thermal conductance; Nanowire; Silicon; Diamond; Non-equilibrium Green’s function