Phonon Conduction in Silicon Nanobeams

Park, W., Shin, D. D., Kim, S. J., Katz, J. S., Park, J., Ahn, C. H., Kodama, T., Asheghi, M., Kenny, T. W., and Goodson, K.E., "Phonon Conduction in Silicon Nanobeams ," Applied Physics Letter, accepted and in press.

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Despite extensive studies on thermal transport in thin silicon films, there has been little work studying thermal conductivity of single-crystal rectangular, cross-section nanobeams that are commonly used in many applications, such as nanoelectronics (FinFETs), nano-electromechanical systems (NEMS), and nanophotonics. Here, we report experimental data on thermal conductivity of silicon nanobeams of thickness ~78 nm and widths ~65 nm, 170 nm, 270 nm, 470 nm and 970 nm. The experimental data agree well (within ~9 %) with the predictions of a thermal conductivity model that uses a combination of bulk mean free paths obtained from ab initio calculations and suppression function derived from 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 × 65 nm nanobeam is ~ 32 Wm-1K-1, which is roughly a factor of two smaller than that of a 78 nm thick film.

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