Controlling Electron-Phonon Interactions in Graphene at Ultrahigh Carrier Densities

Abstract

We report on the temperature dependent electron transport in graphene at different carrier densities $n$. Employing an electrolytic gate, we demonstrate that $n$ can be adjusted up to $4\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$ for both electrons and holes. The measured sample resistivity $\ensuremath{\rho}$ increases linearly with temperature $T$ in the high temperature limit, indicating that a quasiclassical phonon distribution is responsible for the electron scattering. As $T$ decreases, the resistivity decreases more rapidly following $\ensuremath{\rho}(T)\ensuremath{\sim}{T}^{4}$. This low temperature behavior can be described by a Bloch-Gr\"uneisen model taking into account the quantum distribution of the two-dimensional acoustic phonons in graphene. We map out the density dependence of the characteristic temperature ${\ensuremath{\Theta}}_{\mathrm{BG}}$ defining the crossover between the two distinct regimes, and show that, for all $n$, $\ensuremath{\rho}(T)$ scales as a universal function of the normalized temperature $T/{\ensuremath{\Theta}}_{\mathrm{BG}}$.