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.
Hochbaum A I, Chen R K, Delgado R D, Liang W J, Garnett E C, Najarian M, Majumdar A and Yang P D 2008 Nature451 163
[10]
Boukai A I, Bunimovich Y, Tahir-Kheli J, Yu J K, Goddard W A and Heath J R 2008 Nature451 168
[11]
Zhao Y S, Yang L N, Kong L Y, Nai M H, Liu D, Wu J, Liu Y, Chiam S Y, Chim W K, Lim C T, Li B W, Thong J T L and Hippalgaonkar K 2017 Adv. Funct. Mater.27 1702824
[12]
Zhao Y S, Liu D, Chen J, Zhu L Y, Belianinov A, Ovchinnikova O S, Unocic R R, Burch M J, Kim S, Hao H F, Pickard D S, Li B W and Thong J T L 2017 Nat. Commun.8 15919