Impact of torsion and disorder on the thermal conductivity of Si nanowires: A nonequilibrium molecular dynamics study

Abstract

In this paper, we investigate the thermal transport in Si nanowires by using nonequilibrium molecular dynamics simulations (NEMD). We focus on the effects of axial torsion and impurity on the thermal conductivity of the Si nanowires. Stillinger–Weber interatomic potential is employed to describe the interaction between silicon atoms. Also, Tersoff potential is used to simulate the thermal conductivity of Si nanowires with carbon impurity. Furthermore, the dependence of the thermal conductivity on tensile strain and mean temperature is evaluated in different crystallography directions such as directions [100], [110] and [111]. We find that by increasing the torsional angle and the impurity concentration, the thermal conductivity of the nanowires at all three crystallography directions decreases. As well as, we realized that the thermal conductivity of the strained Si nanowires decreases at [100] direction but continuously increases for [110] and [111] directions. Our simulation results exhibit that increasing the mean temperature of the system leads to reduction in the thermal conductivity. Our findings provide insights into the thermal control of silicon-based nanodevices for different applications such as thermoelectric ones.