Thermal conduction and rectification phenomena in nanoporous silicon membranes

Hahn, Konstanze R.; Melis, Claudio; Colombo, Luciano

doi:10.1039/d2cp00775d

Cited by 4 publications

(2 citation statements)

References 36 publications

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“…Since the intrinsic phonon properties are seen to depend primarily on nanosystem porosity, regardless of the specific geometry, the variations in thermal conductivity at a given porosity observed in Figure can be attributed to the permeability K , which only depends on geometry. Permeability not only accounts for the classical volume reduction effect but also captures nanoscale geometrical effects, and it can be used to reinterpret correlations between thermal conductivities and geometric descriptors observed in the literature. − For example, the differences between the permeability and the surface-to-volume ratio justify why the latter is not a general proxy for thermal conductivity in nanostructured systems . The influence of the neck size on the permeability can be investigated by identifying the neck size with the channel diameter D and using the 3D geometrical relation, D = 2(1 – ϕ) Ψd /3ϕ in eq , as discussed in SI section 5A.…”

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confidence: 99%

Universal Behavior of Highly Confined Heat Flow in Semiconductor Nanosystems: From Nanomeshes to Metalattices

et al. 2023

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Nanostructuring on length scales corresponding to phonon mean free paths provides control over heat flow in semiconductors and makes it possible to engineer their thermal properties. However, the influence of boundaries limits the validity of bulk models, while first-principles calculations are too computationally expensive to model real devices. Here we use extreme ultraviolet beams to study phonon transport dynamics in a 3D nanostructured silicon metalattice with deep nanoscale feature size and observe dramatically reduced thermal conductivity relative to bulk. To explain this behavior, we develop a predictive theory wherein thermal conduction separates into a geometric permeability component and an intrinsic viscous contribution, arising from a new and universal effect of nanoscale confinement on phonon flow. Using experiments and atomistic simulations, we show that our theory applies to a general set of highly confined silicon nanosystems, from metalattices, nanomeshes, porous nanowires, to nanowire networks, of great interest for next-generation energy-efficient devices.

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confidence: 99%

Universal Behavior of Highly Confined Heat Flow in Semiconductor Nanosystems: From Nanomeshes to Metalattices

et al. 2023

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“…In solid-state systems, various mechanisms have previously been proposed to achieve thermal rectification. These mechanisms include, but are not limited to, variations in thermal boundary resistances between two materials, − the presence of anharmonic interatomic potentials, dissimilar bulk materials exhibiting distinct temperature-dependent thermal conductivities ( k ), − and the use of asymmetrically structured materials (such as those involving load mass, ballistic scattering, mass gradient ,, and asymmetric thermal radiation − ). While various metrics and definitions for the thermal rectification efficiency (η) are found in the literature, here we define by η as the ratio between the heat fluxes: , η = italicF max − italicF min italicF min where F max ( F min ) is the absolute value of the maximum (minimum) thermal flux.…”

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confidence: 99%

Far-Field Radiative Thermal Rectification Based on Asymmetric Emissivity

Ng,

El Sachat,

Jaramillo-Fernandez

et al. 2023

ACS Appl. Opt. Mater.

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This experimental study investigates thermal rectification via asymmetric far-field thermal radiation on a fused silica slab. An asymmetrical distribution of surface emissivity is created over the device by partially covering the fused silica with a 100 nm thick aluminum film. The slab is subjected to a thermal bias, and when this bias is reversed, a small temperature difference is observed between the different configurations. This temperature difference arises from the difference in emissivity between the aluminum layer and fused silica, resulting in the transfer of thermal energy to the surrounding environment through radiation. Experimental findings are supported by finite element simulations, which not only confirm the measured values but also provide valuable insights into the rectification efficiency of the system. The rectification efficiency is found to be approximately 50% at room temperature for a thermal bias of 140 K. Simulations, which are performed by considering different environmental conditions experienced by the radiation and free convection processes, provide further insight into the underlying thermal rectification mechanism. These simulations consider an environmental temperature of 4 K for thermal radiation and an ambient temperature of 294 K for free convection and reveal an enhanced rectification effect with a rectification efficiency up to 600% when a thermal bias of 195 K is applied. This result emphasizes the significance of considering both convection and radiation in the thermal management and rectification of asymmetric systems. The outcomes of this study further our understanding of the thermal rectification phenomenon. They also show the importance of system asymmetry, emissivity disparities, environmental conditions, and the interplay between convection and radiation. Furthermore, the findings have implications for heat transfer and rectification in asymmetric systems, offering potential applications in areas such as energy harvesting, thermal management, and heat transfer optimization in electronic devices.

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Non-Fourier heat transport in nanosystems

et al. 2023

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Energy transfer in small nano-sized systems can be very different from that in their macroscopic counterparts due to reduced dimensionality, interaction with surfaces, disorder, and large fluctuations. Those ingredients may induce non-diffusive heat transfer that requires to be taken into account on small scales. We provide an overview of the recent advances in this field from the points of view of nonequilibrium statistical mechanics and atomistic simulations. We summarize the underlying basic properties leading to violations of the standard diffusive picture of heat transport and its universal features, with some historical perspective. We complete this scenario by illustrating also the effects of long-range interaction and integrability on non-diffusive transport. Then we discuss how all of these features can be exploited for thermal management, rectification and to improve the efficiency of energy conversion. We conclude with a review on recent achievements in atomistic simulations of anomalous heat transport in single polymers, nanotubes and two-dimensional materials. A short account of the existing experimental literature is also given.

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Thermal conduction and rectification phenomena in nanoporous silicon membranes

Abstract: Non-equilibrium molecular dynamics simulations have been applied to study thermal transport properties, such as thermal conductivity and rectification, in nanoporous Si membranes.

Cited by 4 publications

References 36 publications

Universal Behavior of Highly Confined Heat Flow in Semiconductor Nanosystems: From Nanomeshes to Metalattices

Universal Behavior of Highly Confined Heat Flow in Semiconductor Nanosystems: From Nanomeshes to Metalattices

Far-Field Radiative Thermal Rectification Based on Asymmetric Emissivity

Non-Fourier heat transport in nanosystems

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