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Direct first-principle-based study of mode-wise in-plane phonon transport in ultrathin silicon films

Wang, Qi and Guo, Ruiqiang and Chi, Cheng and Zhang, Kai and Huang, Baoling (2019) Direct first-principle-based study of mode-wise in-plane phonon transport in ultrathin silicon films. International Journal of Heat and Mass Transfer, 143 . Art. No. 118507. ISSN 0017-9310. doi:10.1016/j.ijheatmasstransfer.2019.118507.

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Fundamental understanding of thermal transport properties in ultrathin Si-based films is essential for the thermal management of nanoelectronic and nanophotonic devices. Using Density-Functional-based tight-binding method and direct iterative solution of linearized Boltzmann transport equation without empirical assumptions, we systematically investigated mode-wise in-plane phonon transport in ultrathin Si films of a few nanometer thickness (0.77–1.90 nm) and the effects of surface morphology. The dimensionality reduction of these films leads to quantum confinement and softening of silicon bonds and in turn changes the dispersion and phonon-phonon interactions. The ultrathin Si films with naturally reconstructed surfaces show a counterintuitively high in-plane thermal conductivity (∼30 W/m-K at 300 K) with relatively weak size dependence and large acoustic phonon contribution, demonstrating that dimensionality reduction alone cannot suppress phonon transport in ultrathin films efficiently. The in-plane thermal conductivities of ultrathin films are very sensitive to surface defects and even atomic-level surface defects can induce up to 10-fold reduction in thermal conductivity due to much enhanced phonon scatterings in low frequency regime. Our direct first-principle-based calculations also show that the conventional modeling of thin films with bulk properties and suppression function may lead to large uncertainty when applied to ultrathin films.

Item Type:Article
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Guo, Ruiqiang0000-0002-1585-9980
Additional Information:© 2019 Elsevier Ltd. Received 7 May 2019, Revised 19 July 2019, Accepted 31 July 2019, Available online 16 August 2019.
Funding AgencyGrant Number
National Natural Science Foundation of China61874035
Science and Technology Planning Project of Guangdong Province2017A050506053
Science and Technology Program of Guangzhou201704030107
Hong Kong General Research Fund16213015
Subject Keywords:Mode-wise phonon transport; Ultrathin Si film; Surface defect; First principles
Record Number:CaltechAUTHORS:20190816-140904994
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Official Citation:Qi Wang, Ruiqiang Guo, Cheng Chi, Kai Zhang, Baoling Huang, Direct first-principle-based study of mode-wise in-plane phonon transport in ultrathin silicon films, International Journal of Heat and Mass Transfer, Volume 143, 2019, 118507, ISSN 0017-9310, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97958
Deposited By: Tony Diaz
Deposited On:16 Aug 2019 21:32
Last Modified:16 Nov 2021 17:35

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