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 $4\times {10}^{14}{\mathrm{cm}}^{-2}$ for both electrons and holes. The measured sample resistivity $\rho$ 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 $\rho (T)\sim T^4$. This low temperature behavior can be described by a Bloch-Grüneisen 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 ${\Theta }_{\mathrm{BG}}$ defining the crossover between the two distinct regimes, and show that, for all $n$, $\rho (T)$ scales as a universal function of the normalized temperature $T/{\Theta }_{\mathrm{BG}}$. DOI: http://dx.doi.org/10.1103/PhysRevLett.105.256805 © 2010 The American Physical Society