Enhancement of the power factor in two‐phase silicon–boron nanocrystalline alloys

Narducci, Dario; Lorenzi, Bruno; Zianni, Xanthippe; Neophytou, Neophytos; Frabboni, Stefano; Gazzadi, Gian Carlo; Roncaglia, Alessandro; Suriano, Francesco

doi:10.1002/pssa.201300130

Cited by 27 publications

(27 citation statements)

References 21 publications

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“…[3][4][5][6][7][8][9][10][11][12][13] Due to this drastic reduction in j, which is quickly reaching the amorphous limit, further improvements might come from the thermoelectric power factor (PF ¼ S 2 r), for which to date limited progress has been made. However, a small set of recent studies have demonstrated that a significant improvement in the PF of Si is sometimes possible for polycrystalline Si [14][15][16] where built-in potential barriers are created by nanoscale grain boundaries or voids, 17 combined with high levels of doping. These potential barriers increase energy filtering and as a consequence, the Si Seebeck coefficient.…”

Section: à3mentioning

confidence: 99%

Dislocation loops as a mechanism for thermoelectric power factor enhancement in silicon nano-layers

Bennett

Byrne

Cowley

et al. 2016

Applied Physics Letters

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A more than 70% enhancement in the thermoelectric power factor of single-crystal silicon is demonstrated in silicon nano-films, a consequence of the introduction of networks of dislocation loops and extended crystallographic defects. Despite these defects causing reductions in electrical conductivity, carrier concentration, and carrier mobility, large corresponding increases in the Seebeck coefficient and reductions in thermal conductivity lead to a significant net enhancement in thermoelectric performance. Crystal damage is deliberately introduced in a sub-surface nano-layer within a silicon substrate, demonstrating the possibility to tune the thermoelectric properties at the nano-scale within such wafers in a repeatable, large-scale, and cost-effective way.

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Section: à3mentioning

confidence: 99%

Dislocation loops as a mechanism for thermoelectric power factor enhancement in silicon nano-layers

Bennett

Byrne

Cowley

et al. 2016

Applied Physics Letters

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“…It was concluded that the experimental observations could be interpreted by two combined effects: (i) the presence of energy barriers at the grain boundaries due to the formation of a second-phase, and (ii) the very high Fermi energy level due to the high doping concentrations. The occurrence of a second phase in samples where the TPF enhancement was observed was confirmed in subsequent experiments [22]. Here, we explore the prospects for TPF enhancement in degenerate two-phase semiconductors within BTE and provide a simple compact model that describes TE behavior in such systems.…”

Section: Introductionmentioning

confidence: 57%

Compact Model for Thermoelectric Power Factor Enhancement by Energy Barriers in a Two-phase Composite Semiconductor

Zianni¹,

Neophytou

Narducci

2015

Materials Today: Proceedings

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“…11) and is observed both in experimental studies (blue data point in Fig. 11) as well as theoretical works [26,54]. Furthermore, a more advanced geometry, in which the grain also includes nanometer scale nanovoids achieved even higher power factor, reaching at 22 mW/mK 2 [60].…”

Section: Thermoelectric Properties Of Bulk-size Nanostructured Simentioning

confidence: 68%

“…In our recent works, however, we showed that very large power factors can be achieved in nanocrystalline bulk-like Si materials [26,27,54].…”

Section: Thermoelectric Properties Of Bulk-size Nanostructured Simentioning

confidence: 93%

Prospects of low-dimensional and nanostructured silicon-based thermoelectric materials: findings from theory and simulation

Neophytou

2015

Eur. Phys. J. B

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Original citation: Neophytou, Neophytos. (2015) Prospects of low-dimensional and nanostructured siliconbased thermoelectric materials : findings from theory and simulation. The European Physical Journal B, 88 (4). Permanent WRAP url:http://wrap.warwick.ac.uk/77435 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:"The final publication is available at Springer via http://dx.doi.org/10.1140/epjb/e2015-50673-9 " A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractSilicon based low-dimensional materials receive significant attention as new generation thermoelectric materials after they have demonstrated record low thermal conductivities. Very few works to-date, however, report significant advances with regards to the power factor. In this review we examine possibilities of power factor enhancement in: i) low-dimensional Si channels and ii) nanocrystalline Si materials. For low-D channels we use atomistic simulations and consider ultra-narrow Si nanowires and ultra-thin Si layers of feature sizes below 15nm. Room temperature is exclusively considered. We show that, in general, low-dimensionality does not offer possibilities for power factor improvement, because although the Seebeck coefficient could slightly increase, the conductivity inevitably degrades at a much larger extend. The power factor in these channels, however, can be optimized by proper choice of geometrical parameters such as the transport orientation, confinement orientation, and confinement length scale. Our simulations show that in the case where room temperature thermal conductivities as low as κl=2 W/mK are achieved, the ZT figure of merit of an optimized Si lowdimensional channel could reach values around unity. For the second case of materials, we show that by making effective use of energy filtering, and taking advantage of the inhomogeneity within the nanocrystalline geometry, the underlying potential profile and dopant distribution, large improvements in the thermoelectric power factor can be achieved. The paper is intended...

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Enhancement of the power factor in two‐phase silicon–boron nanocrystalline alloys

Cited by 27 publications

References 21 publications

Dislocation loops as a mechanism for thermoelectric power factor enhancement in silicon nano-layers

Dislocation loops as a mechanism for thermoelectric power factor enhancement in silicon nano-layers

Compact Model for Thermoelectric Power Factor Enhancement by Energy Barriers in a Two-phase Composite Semiconductor

Prospects of low-dimensional and nanostructured silicon-based thermoelectric materials: findings from theory and simulation

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