Bandstructure Effects in Silicon Nanowire Hole Transport

Neophytou, Neophytos; Paul, Abhijeet; Klimeck, Gerhard

doi:10.1109/tnano.2008.2006272

Cited by 56 publications

(100 citation statements)

References 22 publications

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“…More details of the model can be found in our previous works [11,12,24]. iv) Once self-consistency is achieved, we use the linearized Boltzmann transport formalism to compute the low-field mobility of the NW channel.…”

Section: Approachmentioning

confidence: 99%

“…Furthermore, large mobility and on-current densities in NWs compared to bulk have been observed experimentally [9,10]. Low-dimensional channels offer additional degrees of freedom in engineering their properties: i) the length scale of the cross section, ii) the transport orientation, iii) the orientation of the confining surfaces [11,12]. The transport effective mass, carrier velocity, mean free path, and mobility can significantly vary with geometry and strongly influence the performance of devices.…”

Section: Introductionmentioning

confidence: 99%

“…Transport methodologies from semiclassical to fully quantum mechanical were also utilized. Accurate description of the electronic structure is especially important for p-type channels, where strong geometrical confinement, spin-orbit interactions and band coupling can result in warping and nontrivial features of the electronic structure [12,24]. For ultra-narrow p-type NWs, studies have shown that the carrier velocities and mobility largely increase as the diameter is reduced down to D=3nm [10,21,25].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Bandstructure and mobility variations in p-type silicon nanowires under electrostatic gate field

Neophytou

Baumgärtner

Stanojević

et al. 2013

Solid-State Electronics

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The sp 3 d 5 s * -spin-orbit-coupled atomistic tight-binding (TB) model is used for the electronic structure calculation of Si nanowires (NWs), self consistently coupled to a 2D Poisson equation, solved in the cross section of the NW. Upon convergence, the linearized Boltzmann transport theory is employed for the mobility calculation, including carrier scattering by phonons and surface roughness. As the channel is driven into inversion, for [111] and [110] NW devices of diameters D>10nm the curvature of the bandstructure increases and the hole effective mass becomes lighter, resulting in a ~50% mobility increase. Such improvement is large enough to compensate for the detrimental effect of surface roughness scattering. The effect is very similar to the bandstructure variations and mobility improvement observed under geometric confinement, however, in this case confinement is caused by electrostatic gating. We provide explanations for this behavior based on features of the heavy-hole band. This effect could be exploited in the design of p-type NW devices. We note, finally, that the "apparent" mobility of low dimensional short channel transistors is always lower than the intrinsic channel diffusive mobility due to the detrimental influence of the so called "ballistic" mobility.

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Section: Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bandstructure and mobility variations in p-type silicon nanowires under electrostatic gate field

Neophytou

Baumgärtner

Stanojević

et al. 2013

Solid-State Electronics

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“…A full 3D atomistic quantum transport model [9,10,11] can provide the device characteristics, however, this model is computationally time consuming [12]. Recently, a 2D top of the barrier (ToB) atomistic quantum transport model [13,14,15] has been used for speedy simulation and analysis of SiNW FET device characteristics, which provides significant insight. However, to use the ToB model reliably, it is essential to understand the device regime where this model is valid.…”

mentioning

confidence: 99%

On the Validity of the Top of the Barrier Quantum Transport Model for Ballistic Nanowire MOSFETs

Paul

Mehrotra

Klimeck

et al. 2009

2009 13th International Workshop on Computational Electronics

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“…1a, 1b) to achieve the highest possible power factor, and illustrate the design principles behind this. For this analysis, we employ the atomistic sp 3 d 5 s*-spin-orbit-coupled (sp 3 d 5 s*-SO) tight-binding (TB) model [17,18,19,20,21,22,23] coupled to Linearized Boltzmann transport as described in Refs. [14,24,25].…”

Section: Dos(e)mentioning

confidence: 99%

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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Bandstructure Effects in Silicon Nanowire Hole Transport

Abstract: The dispersion features and quantization behavior, although a complicated function of physical and electrostatic confinement, can be explained at first order by looking at the anisotropic shape of the heavy-hole valence band.

Cited by 56 publications

References 22 publications

Bandstructure and mobility variations in p-type silicon nanowires under electrostatic gate field

Bandstructure and mobility variations in p-type silicon nanowires under electrostatic gate field

On the Validity of the Top of the Barrier Quantum Transport Model for Ballistic Nanowire MOSFETs

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

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