Curvature effect on the phonon thermal conductivity of dielectric nanowires

Abstract

Phonon thermal conductivity of nanowires is very different from bulk materials and is of great importance to the applications of nanowires in nanoelectronics, sensors, and energy conversion and storage. Past theoretical studies usually assume that nanowires are perfectly straight and so as the analysis of experimental data. However, nanowires are not always straight with regards to both characterization and application. The curvature of nanowires could significantly change the thermal conductivity and thus bring uncertainty in characterization and product reliability due to its effect on ballistic phonon transport. In this study, the curvature effect on phonon thermal conductivity of dielectric nanowires is investigated using a phonon transport Monte Carlo simulator. It is found that the curvature impedes ballistic phonon transport in nanowires, causes an increase in the effective transport length of the thermal resistor, and thus reduces the effective thermal conductivity of nanowires. Such geometrical effect could be utilized as a new mechanism to tune the thermal conductivity of nanostructures.