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Gated Si nanowires for large thermoelectric power factors
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Neophytou, Neophytos and Kosina, Hans (2014) Gated Si nanowires for large thermoelectric power factors. Applied Physics Letters, Volume 105 (Number 7). Article number 073119. doi:10.1063/1.4893977 ISSN 0003-6951.
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Official URL: http://dx.doi.org/10.1063/1.4893977
Abstract
We investigate the effect of electrostatic gating on the thermoelectric power factor of p-type Si nanowires (NWs) of up to 20 nm in diameter in the [100], [110], and [111] crystallographic transport orientations. We use atomistic tight-binding simulations for the calculation of the NW electronic structure, coupled to linearized Boltzmann transport equation for the calculation of the thermoelectric coefficients. We show that gated NW structures can provide ∼5× larger thermoelectric power factor compared to doped channels, attributed to their high hole phonon-limited mobility, as well as gating induced bandstructure modifications which further improve mobility. Despite the fact that gating shifts the charge carriers near the NW surface, surface roughness scattering is not strong enough to degrade the transport properties of the accumulated hole layer. The highest power factor is achieved for the [111] NW, followed by the [110], and finally by the [100] NW. As the NW diameter increases, the advantage of the gated channel is reduced. We show, however, that even at 20 nm diameters (the largest ones that we were able to simulate), a ∼3× higher power factor for gated channels is observed. Our simulations suggest that the advantage of gating could still be present in NWs with diameters of up to ∼40 nm.
| Item Type: | Journal Article | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | ||||||||||
| Journal or Publication Title: | Applied Physics Letters | ||||||||||
| Publisher: | American Institute of Physics | ||||||||||
| ISSN: | 0003-6951 | ||||||||||
| Official Date: | 2014 | ||||||||||
| Dates: |
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| Volume: | Volume 105 | ||||||||||
| Number: | Number 7 | ||||||||||
| Article Number: | Article number 073119 | ||||||||||
| DOI: | 10.1063/1.4893977 | ||||||||||
| Status: | Peer Reviewed | ||||||||||
| Publication Status: | Published | ||||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||||
| Funder: | Seventh Framework Programme (European Commission) (FP7) | ||||||||||
| Grant number: | FP7-263306 |
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