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Nat Nanotechnol. 2016 Jun;11(6):509-14. doi: 10.1038/nnano.2016.17. Epub 2016 Mar 7.

Radiative heat conductances between dielectric and metallic parallel plates with nanoscale gaps.

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Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.


Recent experiments have demonstrated that radiative heat transfer between objects separated by nanometre-scale gaps considerably exceeds the predictions of far-field radiation theories. Exploiting this near-field enhancement is of great interest for emerging technologies such as near-field thermophotovoltaics and nano-lithography because of the expected increases in efficiency, power conversion or resolution in these applications. Past measurements, however, were performed using tip-plate or sphere-plate configurations and failed to realize the orders of magnitude increases in radiative heat currents predicted from near-field radiative heat transfer theory. Here, we report 100- to 1,000-fold enhancements (at room temperature) in the radiative conductance between parallel-planar surfaces at gap sizes below 100 nm, in agreement with the predictions of near-field theories. Our measurements were performed in vacuum gaps between prototypical materials (SiO2-SiO2, Au-Au, SiO2-Au and Au-Si) using two microdevices and a custom-built nanopositioning platform, which allows precise control over a broad range of gap sizes (from <100 nm to 10 μm). Our experimental set-up will enable systematic studies of a variety of near-field-based thermal phenomena, with important implications for thermophotovoltaic applications, that have been predicted but have defied experimental verification.


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