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Monte Carlo phonon transport simulations in hierarchically disordered silicon nanostructures
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Chakraborty, Dhritiman, Foster, Samuel and Neophytou, Neophytos (2018) Monte Carlo phonon transport simulations in hierarchically disordered silicon nanostructures. Physical Review B (Condensed Matter and Materials Physics), 98 (11). 115435 . doi:10.1103/PhysRevB.98.115435
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WRAP-Monte-Carlo-phonon-transport-hierarchically-silicon-nanostructures-Neophytou-2018.pdf - Accepted Version - Requires a PDF viewer. Download (2390Kb) | Preview |
Official URL: http://dx.doi.org/10.1103/PhysRevB.98.115435
Abstract
Hierarchical material nanostructuring is considered to be a very promising direction for high performance thermoelectric materials. In this work we investigate thermal transport in hierarchically nanostructured silicon. We consider the combined presence of nanocrystallinity and nanopores, arranged under both ordered and randomized positions and sizes, by solving the Boltzmann transport equation using the Monte Carlo method. We show that nanocrystalline boundaries degrade the thermal conductivity more drastically when the average grain size becomes smaller than the average phonon mean-free path. The introduction of pores degrades the thermal conductivity even further. Its effect, however, is significantly more severe when the pore sizes and positions are randomized, as randomization results in regions of higher porosity along the phonon transport direction, which introduce significant thermal resistance. We show that randomization acts as a large increase in the overall effective porosity. Using our simulations, we show that existing compact nanocrystalline and nanoporous theoretical models describe thermal conductivity accurately under uniform nanostructured conditions, but overestimate it in randomized geometries. We propose extensions to these models that accurately predict the thermal conductivity of randomized nanoporous materials based solely on a few geometrical features. Finally, we show that the new compact models introduced can be used within Matthiessen's rule to combine scattering from different geometrical features within
| Item Type: | Journal Article | ||||||
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| Subjects: | Q Science > QC Physics | ||||||
| Divisions: | Faculty of Science > Engineering | ||||||
| Library of Congress Subject Headings (LCSH): | Nanostructures, Phonons, Monte Carlo method | ||||||
| Journal or Publication Title: | Physical Review B (Condensed Matter and Materials Physics) | ||||||
| Publisher: | American Physical Society | ||||||
| ISSN: | 1098-0121 | ||||||
| Official Date: | 25 September 2018 | ||||||
| Dates: |
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| Date of first compliant deposit: | 27 September 2018 | ||||||
| Volume: | 98 | ||||||
| Number: | 11 | ||||||
| Article Number: | 115435 | ||||||
| DOI: | 10.1103/PhysRevB.98.115435 | ||||||
| Status: | Peer Reviewed | ||||||
| Publication Status: | Published | ||||||
| Publisher Statement: | ©2018 American Physical Society | ||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||
| Copyright Holders: | American Physical Society | ||||||
| RIOXX Funder/Project Grant: |
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