Near-field thermal radiation between deep subwavelength membranes driven by corner and edge modes

Abstract

We demonstrate that the thermal radiation between deep subwavelength membranes of silicon carbide (SiC) exhibits a maximum enhancement over that of infinite SiC surfaces separated by the same vacuum gap. Based on fluctuational electrodynamics, we show that this enhancement occurs at a separation distance of 200 nm and increases for thinner and colder membranes. This peak arises from the dominant contribution of electromagnetic modes localized at the corner and vertical edges of sufficiently thin membranes, which enable a strong coupling of surface phonon-polaritons appearing along their top and bottom surfaces. These resonant corner and edge modes effectively extend the emission cross-sectional area of the membranes over their geometrical one and, therefore, amplify their thermal radiation.

Journal of Applied Physics 139(8) (2026)