Phonon drag thermopower in graphene in equipartition regime

TL;DR

This paper theoretically investigates how electron-phonon interactions contribute to thermoelectric effects in graphene, highlighting conditions under which phonon drag can dominate the thermopower at various temperatures.

Contribution

It provides a theoretical analysis of phonon drag thermopower in graphene considering intrinsic acoustic phonons and identifies key factors influencing its magnitude.

Findings

Phonon drag contribution depends on Fermi energy and phonon relaxation time.

Weak temperature dependence of phonon drag compared to diffusion thermopower.

High carrier concentration and thermal conductivity enhance phonon drag dominance.

Abstract

This letter calculates the contribution of electron-phonon interaction to thermoelectric effects in graphene. One considers the case of free standing graphene taking into account interaction with intrinsic acoustic phonons. The temperatures considered range from liquid nitrogen to the room level. It has turned out that the contribution to thermoelectromotive force due to electron drag by phonons is determined by the Fermi energy in the sample and phonon relaxation time. The explicit temperature dependence of the contribution to thermoelectromotive force deriving from by phonons is weak in contrast to that due to diffusion, which is directly proportional to temperature. The dependence obtained suggests that at the temperatures considered, a high carrier concentration and for samples with a high thermal conductivity, the phonon drag contribution can become dominant. Thus a theoretical limit has been established for a possible increase of the thermoelectromotive force through electron drag by the intrinsic phonons of graphene.