Phonon conduction in silicon nanobeams

Abstract

Despite extensive studies on thermal transport in thin silicon films, there has been little work studying the thermal conductivity of single-crystal rectangular, cross-sectional nanobeams that are commonly used in many applications such as nanoelectronics (FinFETs), nano-electromechanical systems, and nanophotonics. Here, we report experimental data on the thermal conductivity of silicon nanobeams of a thickness of similar to 78 nm and widths of similar to 65 nm, 170 nm, 270 nm, 470 nm, and 970 nm. The experimental data agree well (within similar to 9%) with the predictions of a thermal conductivity model that uses a combination of bulk mean free paths obtained from ab initio calculations and a suppression function derived from the kinetic theory. This work quantifies the impact of nanobeam aspect ratios on thermal transport and establishes a criterion to differentiate between thin films and beams in studying thermal transport. The thermal conductivity of a 78 nm similar to 65 nm nanobeam is similar to 32 W m(-1) K-1, which is roughly a factor of two smaller than that of a 78 nm thick film. Published by AIP Publishing.