Near-field radiative heat transfer between parallel structures in the deep subwavelength regime

• Published in: Nature nanotechnology Vol. 11; no. 6; pp. 515 - 519
• Main Authors: St-Gelais, Raphael, Zhu, Linxiao, Fan, Shanhui, Lipson, Michal
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2016; Nature Publishing Group
• Subjects: 147/135; 639/766/25; 639/925/927/1021; 639/925/927/359; 639/925/930; Concentration gradient; Conduction; Conduction heating; Far fields; Frequency distribution; Heat transfer; Hot surfaces; letter; Materials Science; Microelectromechanical systems; Nanostructure; Nanotechnology; Nanotechnology and Microengineering; Photovoltaic cells; Photovoltaics; Radiative heat transfer; Separation; Silicon carbide; Temperature gradients; Tensile stress; Thermal buckling; Thermal radiation; Transport
• ISSN: 1748-3387; 1748-3395; 1748-3395
• DOI: 10.1038/nnano.2016.20

A microelectromechanical system is used to bring two parallel beams to sub-100 nm separation and measure the radiative heat transfer between them under a high thermal gradient. Thermal radiation between parallel objects separated by deep subwavelength distances and subject to large thermal gradients (>100 K) can reach very high magnitudes, while being concentrated on a narrow frequency distribution. These unique characteristics could enable breakthrough technologies for thermal transport control 1 , 2 , 3 and electricity generation 4 , 5 , 6 , 7 , 8 (for example, by radiating heat exactly at the bandgap frequency of a photovoltaic cell). However, thermal transport in this regime has never been achieved experimentally due to the difficulty of maintaining large thermal gradients over nanometre-scale distances while avoiding other heat transfer mechanisms, namely conduction. Here, we show near-field radiative heat transfer between parallel SiC nanobeams in the deep subwavelength regime. The distance between the beams is controlled by a high-precision micro-electromechanical system (MEMS). We exploit the mechanical stability of nanobeams under high tensile stress to minimize thermal buckling effects, therefore keeping control of the nanometre-scale separation even at large thermal gradients. We achieve an enhancement of heat transfer of almost two orders of magnitude with respect to the far-field limit (corresponding to a 42 nm separation) and show that we can maintain a temperature gradient of 260 K between the cold and hot surfaces at ∼100 nm distance.