Molecular dynamics simulations for thermal transport behavior of InAs nanotubes: A role of symmetry

Abstract

Molecular dynamics simulations for the indium arsenide (InAs) nanowires and nanotubes are performed to understand the improved (decreased) thermal transport behavior in nanostructured systems. The InAs nanotubes have a significantly reduced heat flow as compared to the nanowire analogue due to the increased surface area to volume effect. A 53% reduction in thermal conductivity was observed with a 17% reduction in the nanowire cross sectional area. Local heat current analysis shows that the interior atoms being removed in nanotubes have the largest local heat current contribution, thereby punching a hole in the middle leading to the largest reduction in thermal conductivity of the material. We then find that the broken symmetry can lower the thermal conductivity even further. As a result, a sweet spot for the lowest thermal conductivity for nanotubes is found at the nearest displacement of the hole from the center due to the two opposing factors: highest local heat currents for the innermost atoms and the effect of broken symmetry. We expect that this new physical mechanism of heat transport in InAs nanotubes can be generalized to other thermoelectric materials such as silicon nanowires and nanotubes to reduce a lattice thermal conductivity even further. (C) 2013 Elsevier B. V. All rights reserved.