Super-Planckian Radiative Heat Transfer between Metallic Surfaces Due to Near-Field and Thin-Film Effects

• Published in: arXiv.org
• Main Authors: Sabbaghi, Payam, Long, Linshuang, Ying, Xiaoyan, Lambert, Lee, Taylor, Sydney, Messner, Christian, Wang, Liping
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 04.05.2020
• Subjects: Aluminum; Blackbody; Electrodynamics; Energy conversion; Far fields; Heat flux; Heat transfer; Heat transmission; Physics - Applied Physics; Physics - Mesoscale and Nanoscale Physics; Polystyrene resins; Radiative heat transfer; Silicon; Temperature gradients; Thickness; Thin films
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1907.09638

In this Letter we experimentally demonstrate that the radiative heat transfer between metallic planar surfaces exceeds the blackbody limit by employing the near-field and thin-film effects. Nanosized polystyrene particles were used to create a nanometer gap between aluminum thin-films of different thicknesses coated on 5x5 mm2 diced silicon chips while the gap spacing is fitted from the near-field measurement with bare Si chips. The experimental results are validated by theoretical calculation based on fluctuational electrodynamics. The near-field radiative heat flux between 13-nm Al thin-film samples at 215 nm gap distance is measured to be 6.4 times over the blackbody limit and 420 times compared to the far-field radiative heat transfer between metallic surfaces with a temperature difference of 65 K. In addition, the theoretical prediction suggests a near-field enhancement of 122 times relative to the blackbody limit and 8000 times over far-field one at 50-nm vacuum gap between 20-nm Al thin-film samples, under the same temperature difference of 65 K. This work will facilitate the understanding and application of near-field radiation to thermal power conversion, noncontact cooling, heat flow management, and optical storage where metallic materials are involved.