Near-field radiative heat transfer between nanostructures in the deep sub-wavelength regime

TL;DR

This study demonstrates experimental measurement of near-field radiative heat transfer between nanostructures at deep sub-wavelength distances, achieving significant heat transfer enhancement and high thermal gradients.

Contribution

The paper presents the first experimental realization of near-field radiative heat transfer at deep sub-wavelength scales using MEMS control and high tensile stress structures.

Findings

Heat transfer enhanced by nearly two orders of magnitude.

Achieved 54 nm separation with a 260 K temperature gradient.

Maintained small separations at large thermal gradients.

Abstract

Radiative heat transfer between parallel objects separated by deep sub-wavelength distances and subject to large thermal gradients (>100 K) could enable breakthrough technologies for electricity generation and thermal transport control. However, thermal transport in this regime has never been achieved experimentally due to the difficulty of maintaining large thermal gradients over nm-scale distances while avoiding other heat transfer mechanism such as conduction. Previous experimental measurement between parallel planes were limited to distances greater than 500 nm (with a 20 K thermal gradient), which is much larger than the theoretically predicted distance (<100 nm) required for most applications. Here we show near-field radiative heat transfer between parallel nanostructures in the deep sub-wavelength regime using high precision micro electromechanical (MEMS) displacement control. We also exploit the high mechanical stability of structures under high tensile stress to minimize thermal buckling effects and maintain small separations at large thermal gradients. We achieve an enhancement of heat transfer of almost two orders of magnitude relative to the far-field limit, which corresponds to a 54 nm separation. We also achieve a high temperature gradient (260 K) between the cold and hot surfaces while maintaining a ~100 nm distance.