Hot phonons in an electrically biased graphene constriction.

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 band gap 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.