Effects of transverse geometry on the thermal conductivity of Si and Ge nanowires

Heris, Hadi Rezaie; Kateb, Movaffaq; Erlingsson, Sigurdur I.; Manolescu, Andrei

doi:10.1016/j.surfin.2022.101834

Cited by 8 publications

(6 citation statements)

References 67 publications

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“…Tubular nanowires increase thermoelectric current due to the lateral electron confinement [57,58] and decrease heat transport due to the strong suppression of phonons with a diameter below the phonon mean free path [25,59]. Coreshell nanowires with polygonal cross-sections show a stronger electron localization at the corners than on the sides of the polygon.…”

Section: Impurities In Different Cross Section Geometriesmentioning

confidence: 99%

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Effect of impurities on charge and heat transport in tubular nanowires

et al. 2023

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We calculate the charge and heat currents carried by electrons, originatingfrom a temperature gradient and a chemical potential difference between the twoends of tubular nanowires with different geometries of the cross-sectional areas:circular, square, triangular, and hexagonal. We consider nanowires based on InAssemiconductor material, and use the Landauer-B ̈uttiker approach to calculate thetransport quantities. We include impurities in the form of delta scatterers and comparetheir effect for different geometries. The results depend on the quantum localizationof the electrons along the edges of the tubular prismatic shell. For example, the effectof impurities on the charge and heat transport is weaker in the triangular shell thanin the hexagonal shell, and the thermoelectric current in the triangular case is severaltimes larger than in the hexagonal case, for the same temperature gradient.

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Section: Impurities In Different Cross Section Geometriesmentioning

confidence: 99%

“…In such structures, electronic properties can be determined by the band alignment between materials, core size, and shell thickness. Similarly, heat transport can be guided or trapped through core-shell nanowires [25].…”

Section: Introductionmentioning

confidence: 99%

Effect of impurities on charge and heat transport in tubular nanowires

et al. 2023

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“…For waste heat energy harvesting with thermoelectric modules, materials with low phonon thermal conductivity (TC) are essentially required to maximize efficiency [2][3][4]. Among different TC reduction strategies [1,[5][6][7], constructing a superlattice (SL) with different materials has been regarded as a promising approach. In SLs, phonons can be extensively scattered by the numerous interfaces.…”

Section: Introductionmentioning

confidence: 99%

“…New phonon transport mechanisms such as phonon hydrodynamic transport might appear [22]. On the other hand, new engineering freedoms, such as transverse geometry modulation [7], orientation engineering, and surface engineering [23], can be applied to control the heat flow. As a result, it would be interesting to know whether the coherent phonon transport in SLNWs would be different from that of the corresponding bulk state or not.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Coherent Phonon Transport in SiGe Nanowires with Dense Si/Ge Interfaces

2022

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The manipulation of phonon transport with coherent waves in solids is of fundamental interest and useful for thermal conductivity design. Based on equilibrium molecular dynamics simulations and lattice dynamics calculations, the thermal transport in SiGe superlattice nanowires with a tuned Si/Ge interface density was investigated by using the core-shell and phononic structures as the primary stacking layers. It was found that the thermal conductivity decreased with the increase of superlattice period lengths (Lp) when Lp was larger than 4 nm. This is because introducing additional Si/Ge interfaces can enhance phonon scattering. However, when Lp<4 nm, the increased interface density could promote heat transfer. Phonon density-of-state analysis demonstrates that new modes between 10 and 14 THz are formed in structures with dense Si/Ge interfaces, which is a signature of coherent phonon transport as those modes do not belong to bulk Si or Ge. The density of the newly generated modes increases with the increase of interface density, leading to an enhanced coherent transport. Besides, with the increase of interface density, the energy distribution of the newly generated modes becomes more balanced on Si and Ge atoms, which also facilitates heat transfer. Our current work is not only helpful for understanding coherent phonon transport but also beneficial for the design of new materials with tunable thermal conductivity.

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“…Low dimensional structures may possess unique mechanical, electrical, optical, and thermoelectric properties. Particularly, silicon nanowires (SiNWs), have demonstrated properties suitable for various advanced applications, [1][2][3], including also low-cost thermoelectric devices and chemo-biological sensors with ultrahigh sensitivity [4,5]. The integration of SiNWs in electronic devices is favored by their compatibility with the well established Si-SiO 2 electronic industrial technology.…”

Section: Introductionmentioning

confidence: 99%

Piezoresistance characterization of silicon nanowires in uniaxial and isostatic pressure variation

Fakhri¹,

Plugaru²,

Sultan³

et al. 2022

Preprint

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Silicon nanowires (SiNWs) are known to exhibit large piezoresistance (PZR) effect, making it suitable for various sensing applications. Here, we report the results of a PZR investigation on randomly distributed and interconnected vertical silicon nanowire arrays as a pressure sensor. The samples were produced from p-type (100) Si wafers using a silver catalysed top-down etching process. The piezoresistance response of these SiNW arrays was analysed by measuring their I-V characteristics under applied uniaxial as well as isostatic pressure. The interconnected SiNWs exhibit increased mechanical stability in comparison with separated or periodic nanowires. The repeatability of the fabrication process and statistical distribution of measurements were also tested on several samples from different batches. A sensing resolution down to roughly 1 mbar pressure was observed with uniaxial force application, and more than two orders of magnitude resistance variation was determined for isostatic pressure below atmospheric pressure.

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Effects of transverse geometry on the thermal conductivity of Si and Ge nanowires

Cited by 8 publications

References 67 publications

Effect of impurities on charge and heat transport in tubular nanowires

Effect of impurities on charge and heat transport in tubular nanowires

Enhancing the Coherent Phonon Transport in SiGe Nanowires with Dense Si/Ge Interfaces

Piezoresistance characterization of silicon nanowires in uniaxial and isostatic pressure variation

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