Kink effects on thermal transport in silicon nanowires

Kinks in nanowires have recently been shown to be able to effectively tune the nanowire thermal conductivities; however, the underlying mechanisms have not been fully understood yet. To further disclose the details of phonon transport in kinked nanowires, here we report on non-equilibrium molecular dynamics studies of thermal transport through kinked and straight silicon nanowires. Results show that kinks can induce additional resistance and lead to lower thermal conductivity for kinked nanowires than that of corresponding straight wires. Detailed analysis indicates that kinks produce additional resistance through reflecting phonons back into their incoming arms. Moreover, through introducing heavier isotope atoms in the kink region, the simulation replicates the experimental observation that defects in the kink regime, instead of posing additional resistance, can actually facilitate thermal transport through deflecting phonons into the opposite arm. (C) 2019 Elsevier Ltd. All rights reserved.