Hot Phonons in an Electrically Biased Graphene Constriction

TL;DR

This paper investigates how phonon interactions in electrically biased graphene constrictions influence energy dissipation, highlighting the significant role of electron-phonon coupling at low carrier densities and high temperatures.

Contribution

It demonstrates the importance of electron-phonon interactions in Joule-heated graphene, especially at low carrier densities, advancing understanding of energy dissipation mechanisms.

Findings

Electron-phonon interactions are significant in gapless graphene at low carrier densities.

Phonon lifetime is affected by carrier interactions, especially at high temperatures.

Graphene's lack of a bandgap influences phonon decay processes.

Abstract

Phonon carrier interactions can have significant impact on device performance. They can be probed by measuring the phonon lifetime, which reflects the interaction strength of a phonon with other quasi-particles in particular charge carriers as well as its companion phonons. The carrier phonon and phonon-phonon contributions to the phonon lifetime can be disentangled from temperature dependent studies. Here, we address the importance of phonon carrier interactions in Joule-heated graphene constrictions in order to contribute to the understanding of energy dissipation in graphene based electronic devices. We demonstrate that gapless graphene grants electron phonon interactions uncommon significance in particular at low carrier density. In conventional semiconductors, the bandgap usually prevents the decay of phonons through electron-hole generation and also in metals or other semimetals the Fermi temperature is excessively large to enter the regime where electron phonon coupling plays such a dominant role as in graphene in the investigated phonon temperature regime from 300 to 1600 K.