Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation
- Creators
- Yang, Lina
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Minnich, Austin J.
Abstract
Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.
Additional Information
© 2017 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ Received: 16 December 2016. Accepted: 03 February 2017. Published online: 14 March 2017. The authors thank Lucas Lindsay for providing the Si dispersion and phonon-phonon lifetimes, and Bolin Liao and Jiawei Zhou for providing electron-phonon lifetimes. This work was supported by the DARPA MATRIX program under Award Number HR0011-15-2-0039. Author Contributions: Lina Yang and Austin J. Minnich wrote this manuscript. All authors reviewed the manuscript. The authors declare no competing financial interests.Attached Files
Published - srep44254.pdf
Erratum - srep46771.pdf
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Additional details
- PMCID
- PMC5349535
- Eprint ID
- 75231
- Resolver ID
- CaltechAUTHORS:20170320-090609578
- Defense Advanced Research Projects Agency (DARPA)
- HR0011-15-2-0039
- Created
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2017-03-20Created from EPrint's datestamp field
- Updated
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2022-03-29Created from EPrint's last_modified field