# A graphene Zener-Klein transistor cooled by a hyperbolic substrate

## TL;DR

This paper demonstrates that Zener-Klein tunneling in high-mobility graphene on hBN enables a novel cooling pathway via hyperbolic phonon polaritons, enhancing thermal management in nanoelectronic devices.

## Contribution

It reveals a new cooling mechanism involving hyperbolic phonon polaritons triggered by Zener-Klein tunneling in graphene on hBN, with implications for power and RF electronics.

## Key findings

- Zener-Klein tunneling induces hyperbolic phonon polariton emission.
- HPP emission provides a super-Planckian cooling pathway.
- Graphene on BN transistors show improved thermal management.

## Abstract

Engineering of cooling mechanisms is a bottleneck in nanoelectronics. Whereas thermal exchanges in diffusive graphene are mostly driven by defect assisted acoustic phonon scattering, the case of high-mobility graphene on hexagonal Boron Nitride (hBN) is radically different with a prominent contribution of remote phonons from the substrate. A bi-layer graphene on hBN transistor with local gate is driven in a regime where almost perfect current saturation is achieved by compensation of the decrease of the carrier density and Zener-Klein tunneling (ZKT) at high bias. Using noise thermometry, we show that this Zener-Klein tunneling triggers a new cooling pathway due to the emission of hyperbolic phonon polaritons (HPP) in hBN by out-of-equilibrium electron-hole pairs beyond the super-Planckian regime. The combination of ZKT-transport and HPP-cooling promotes graphene on BN transistors as a valuable nanotechnology for power devices and RF electronics.