Tuning Thermal Conductivity in Si Nanowires with Patterned StructuresSupported by the National Natural Science Foundation of China (Grant No. 11875047).

Abstract

Tuning the thermal conductivity of silicon nanowires (Si-NWs) is essential for realization of future thermoelectric devices. The corresponding management of thermal transport is strongly related to the scattering of phonons, which are the primary heat carriers in Si-NWs. Using the molecular dynamics method, we find that the scattering of phonons from internal body defects is stronger than that from surface structures in the low-porosity range. Based on our simulations, we propose the concept of an exponential decay in thermal conductivity with porosity, specifically in the low-porosity range. In contrast, the thermal conductivity of Si-NWs with a higher porosity approaches the amorphous limit, and is insensitive to specific phonon scattering processes. Our findings contribute to a better understanding of the tuning of thermal conductivity in Si-NWs by means of patterned nanostructures, and may provide valuable insights into the optimal design of one-dimensional thermoelectric materials.