Enhancement of near-field radiative heat transfer using polar dielectric thin films

Abstract

Thermal radiative emission from a hot surface to a cold surface plays an important role in many applications, including energy conversion, thermal management, lithography, data storage and thermal microscopy. Recent studies on bulk materials have confirmed long-standing theoretical predictions indicating that when the gap between the surfaces is reduced to tens of nanometres, well below the peak wavelength of the blackbody emission spectrum, the radiative heat flux increases by orders of magnitude. However, despite recent attempts, whether such enhancements can be obtained in nanoscale dielectric films thinner than the penetration depth of thermal radiation, as suggested by theory, remains experimentally unknown. Here, using an experimental platform that comprises a heat-flow calorimeter with a resolution of about 100 pW (ref. 7), we experimentally demonstrate a dramatic increase in near-field radiative heat transfer, comparable to that obtained between bulk materials, even for very thin dielectric films (50-100 nm) when the spatial separation between the hot and cold surfaces is comparable to the film thickness. We explain these results by analysing the spectral characteristics and mode shapes of surface phonon polaritons, which dominate near-field radiative heat transport in polar dielectric thin films.

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“…1), have been reported in [28][29][30]. Further enhancement of heat exchange and its spatial modulation were observed with coated or 'island-decorated' samples [31,32]. We shall comment on a few other recent references later in this paper.…”

Thermal conductance and thermoelectric figure of merit of C60 -based single-molecule junctions: Electrons, phonons, and photons

“…In particular, we compute κ pt for nanometer-sized gaps following Ref. 41. In what follows, we briefly describe the main features of our methods and refer to the above-mentioned references for further details.…”

Near-Field Heat Transfer between Multilayer Hyperbolic Metamaterials

“…It is well known that in this distance regime the radiative heat flux can be much larger than that of a blackbody due to the extra-contribution of evanescent waves such as surface phonon polaritons [33][34][35][36][37], for instance. This super-Planckian effect has been measured by many different experiments using different geometries and materials [38][39][40][41][42][43][44][45][46][47][48][49][50], in the past 10 years. So far, there is only one experiment that has measured the heat flux of an HM [27], although HM seem to have quite interesting features for near-field thermal radiation.…”