Thermal resistance of twist boundaries in silicon nanowires by nonequilibrium molecular dynamics
JK Bohrer and K Schroer and L Brendel and DE Wolf, AIP ADVANCES, 7, 045105 (2017).
The thermal boundary resistance (Kapitza resistance) of (001) twist boundaries in silicon is investigated by nonequilibrium molecular dynamics simulations. In order to enable continuous adjustment of the mismatch angle, a cylindrical geometry with fixed atomic positions at the boundaries is devised. The influence of the boundary conditions on the Kapitza resistance is removed by means of a finite size analysis. Due to the diamond structure of silicon, twist boundaries with mismatch angles phi and 90 degrees - phi are not equivalent, whereas those with +/-phi or with 90 degrees +/- phi are. The Kapitza resistance increases with mismatch angle up to 45 degrees, where it reaches a plateau around 1.56 +/- 0.05 K m(2)/GW. Between 80 degrees and the 90 degrees Sigma 1 grain boundary it drops by about 30%. Surprisingly, lattice coincidence at other angles (Sigma 5, Sigma 13, Sigma 27, Sigma 25) has no noticable effect on the Kapitza resistance. However, there is a clear correlation between the Kapitza resistance and the width of a non-crystalline layer at the twist boundaries. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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