Thermal rectification and phonon scattering in asymmetric silicon nanoribbons

Abstract

Thermal rectification is an interesting phenomenon and has important potential applications in improving the thermal management of electronics and saving energy. Exploring thermal rectification phenomena and understanding the mechanism are very necessary and important. This paper reports the investigation of the thermal conductivity and thermal rectification of asymmetric silicon nanoribbons by the non-equilibrium molecular dynamics simulation. The results indicate that the thermal conductivity of the nanoribbon is only on the order of 100 Wm−1K−1. Thermal rectification is observed in silicon nanoribbons at different temperatures, geometry aspects, and ribbon length. The thermal conductivity is apparently larger when heat flows from the thin end to the thick end. The larger the aspect ratio of the thick end to thin end is, the larger the thermal rectification. The rectification coefficient does not change much in the ribbon length ranges from 8.1 nm to 21.7 nm. The longitudinal phonon scattering in the silicon nanoribbon at different frequency is investigated by the phonon wave packet dynamic simulation. The results show that the phonon transmission coefficient is sensitive to frequency and transverse phonons are generated during the scattering. Decreasing the thin end width will reduce the transmission coefficient due to the scattering at the slope boundary.