Geometrical quasi-ballistic effects on thermal transport in nanostructured devices

Alajlouni, Sami; Beardo, Albert; Sendra, Lluc; Ziabari, Amirkoushyar; Bafaluy, J.; Camacho, J.; Xuan, Yi; Álvarez, F. X.; Shakouri, Ali

doi:10.1007/s12274-020-3129-6

Cited by 11 publications

(9 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In our experiments, |T| max < 20 K; thus, the observed deviations between the theoretical predictions and the measured values at very low temperatures are expected (see section S8 for details). We note that similar experiments (25,26) were explained in terms of nonlocality as described by the Guyer-Krumhansl equation, which reduces to Eq. 1 in the absence of nonlocal effects.…”

Section: Resultsmentioning

confidence: 70%

Observation of second sound in a rapidly varying temperature field in Ge

et al. 2021

Self Cite

View full text Add to dashboard Cite

Second sound is known as the thermal transport regime where heat is carried by temperature waves. Its experimental observation was previously restricted to a small number of materials, usually in rather narrow temperature windows. We show that it is possible to overcome these limitations by driving the system with a rapidly varying temperature field. High-frequency second sound is demonstrated in bulk natural Ge between 7 K and room temperature by studying the phase lag of the thermal response under a harmonic high-frequency external thermal excitation and addressing the relaxation time and the propagation velocity of the heat waves. These results provide a route to investigate the potential of wave-like heat transport in almost any material, opening opportunities to control heat through its oscillatory nature.

show abstract

Section: Resultsmentioning

confidence: 70%

Observation of second sound in a rapidly varying temperature field in Ge

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…For effectively isolated sources, hydrodynamic effects become relevant when line width L is on the same scale as the phonon mean free paths ∼l; thus, the non-Fourier terms in eq 1 reduce the heat flux, compared to Fourier's law, in agreement with experiments. [5][6][7][8][9]12,44 This phenomenon is analogous to a friction that arises from the large gradients in heat flux that impedes heat flow, referred to as a viscous resistance. 38 In other words, when line width L is on the same scale as ∼l, there is not enough resistive phonon collisions to scatter the heat outward in all directions as diffusion assumes.…”

Section: Resultsmentioning

confidence: 99%

“…21 The predictability of eq 1 has been recently validated in compact and holey films, and thermoreflectance experiments in silicon, with excellent agreement. 21,22,44 As discussed in ref., 21 the applicability of the model with ab initio parameters (κ, l, and τ) is restricted to geometries where edge effects produced by two different boundaries do not overlap, i.e. when boundaries are separated by a distance larger than 2l.…”

mentioning

confidence: 96%

A General and Predictive Understanding of Thermal Transport from 1D- and 2D-Confined Nanostructures: Theory and Experiment

et al. 2021

Self Cite

View full text Add to dashboard Cite

Heat management is crucial in the design of nanoscale devices as the operating temperature determines their efficiency and lifetime. Past experimental and theoretical works exploring nanoscale heat transport in semiconductors addressed known deviations from Fourier's law modeling by including effective parameters, such as a size-dependent thermal conductivity. However, recent experiments have qualitatively shown behavior that cannot be modeled in this way. Here, we combine advanced experiment and theory to show that the cooling of 1D-and 2D-confined nanoscale hot spots on silicon can be described using a general hydrodynamic heat transport model, contrary to previous understanding of heat flow in bulk silicon. We use a comprehensive set of extreme ultraviolet scatterometry measurements of nondiffusive transport from transiently heated nanolines and nanodots to validate and generalize our ab initio model, that does not need any geometrydependent fitting parameters. This allows us to uncover the existence of two distinct time scales and heat transport mechanisms: an interface resistance regime that dominates on short time scales and a hydrodynamic-like phonon transport regime that dominates on longer time scales. Moreover, our model can predict the full thermomechanical response on nanometer length scales and picosecond time scales for arbitrary geometries, providing an advanced practical tool for thermal management of nanoscale technologies. Furthermore, we derive analytical expressions for the transport time scales, valid for a subset of geometries, supplying a route for optimizing heat dissipation.

show abstract

“…Furthermore, this reduction is greater when the intercanal distance ( P ) is reduced, indicating that the reduction is associated with the transversal interconnections. The physical reasons for this reduction in thermal conductivity can be explained by the heat transport eq , known as the Guyer–Krumhansl equation (GK), which generalizes Fourier’s law by including nonlocal effects. − This equation predicts a heat flux reduction in a region of size l near the Bi 2 Te 3 nanowire surface due to phonon-boundary scattering that has its origin in the Laplacian term of the GK equation. By analogy to classical fluid mechanics, this term can be interpreted as a heat viscosity effect.…”

Section: Resultsmentioning

confidence: 99%

“…Heat conduction in the semiconductor domains is described using the Kinetic Collective Model (KCM), consisting of the energy conservation and the hydrodynamic heat transport equations in steady state 16 − 18 where κ = 2.3 W·m –1 ·K –1 is the Bi 2 Te 3 bulk lattice thermal conductivity and is a weighted phonon mean free path average, known as nonlocal length. 19 …”

Section: Theory and Calculationmentioning

confidence: 99%

3D Bi₂Te₃ Interconnected Nanowire Networks to Increase Thermoelectric Efficiency

Ruiz‐Clavijo

Caballero-Calero

Manzano

et al. 2021

ACS Appl. Energy Mater.

Self Cite

View full text Add to dashboard Cite

3D interconnected nanowire scaffoldings are shown to increase the thermoelectric efficiency in comparison to similar diameter 1D nanowires and films grown under similar electrodeposition conditions. Bi 2 Te 3 3D nanonetworks offer a reduction in thermal conductivity (κ T ) while preserving the high electrical conductivity of the films. The reduction in κ T is modeled using the hydrodynamic heat transport equation, and it can be understood as a heat viscosity effect due to the 3D nanostructuration. In addition, the Seebeck coefficient is twice that of nanowires and films, and up to 50% higher than in a single crystal. This increase is interpreted as a nonequilibrium effect that the geometry of the structure induces on the distribution function of the phonons, producing an enhanced phonon drag. These thermoelectric metamaterials have higher performance and are fabricated with large areas by a cost-effective method, which makes them suitable for up-scale production.

show abstract

Geometrical quasi-ballistic effects on thermal transport in nanostructured devices

Cited by 11 publications

References 32 publications

Observation of second sound in a rapidly varying temperature field in Ge

Observation of second sound in a rapidly varying temperature field in Ge

A General and Predictive Understanding of Thermal Transport from 1D- and 2D-Confined Nanostructures: Theory and Experiment

3D Bi₂Te₃ Interconnected Nanowire Networks to Increase Thermoelectric Efficiency

Contact Info

Product

Resources

About

Geometrical quasi-ballistic effects on thermal transport in nanostructured devices

Cited by 11 publications

References 32 publications

Observation of second sound in a rapidly varying temperature field in Ge

Observation of second sound in a rapidly varying temperature field in Ge

A General and Predictive Understanding of Thermal Transport from 1D- and 2D-Confined Nanostructures: Theory and Experiment

3D Bi2Te3 Interconnected Nanowire Networks to Increase Thermoelectric Efficiency

Contact Info

Product

Resources

About

3D Bi₂Te₃ Interconnected Nanowire Networks to Increase Thermoelectric Efficiency