# Surface phonon-polaritons enhance thermal conduction in SiN nanomembranes

## TL;DR

This study experimentally demonstrates that surface phonon-polaritons significantly enhance thermal conduction in thin amorphous silicon nitride membranes, especially as the membrane thickness decreases and temperature increases.

## Contribution

First experimental evidence showing that surface phonon-polaritons contribute to heat conduction in dielectric membranes, with conductivity doubling at high temperatures in thin SiN membranes.

## Key findings

- Thermal conductivity increases with temperature due to SPhPs.
- SPhPs contribution is more significant in membranes thinner than 100 nm.
- Thermal conductivity can be doubled by SPhPs at high temperatures.

## Abstract

Surface phonon-polaritons can carry energy on the surface of dielectric films and thus are expected to contribute to heat conduction. However, the contribution of surface phonon-polaritons (SPhPs) to thermal transport has not been experimentally demonstrated yet. In this work, we experimentally measure the effective in-plane thermal conductivity of amorphous silicon nitride membrane and show that it can indeed be increased by SPhPs significantly when the membrane thickness scales down. In particular, by heating up a thin membrane (<100 nm) from 300 to 800 K, the thermal conductivity increases twice due to SPhPs contribution.

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Source: https://tomesphere.com/paper/1908.01247