Graphene Transport at High Carrier Densities using a Polymer Electrolyte Gate

TL;DR

This study demonstrates high-density graphene transport using a polymer electrolyte gate, revealing inverse mobility dependence on density, a Bloch-Grüneisen regime up to 100 K, and an unexplained resistivity upturn.

Contribution

It introduces a polymer electrolyte gating method to achieve higher carrier densities in graphene and analyzes the resulting transport phenomena and scattering mechanisms.

Findings

Achieved carrier densities of 6×10^{13}/cm^{2} with polymer electrolyte gating.

Mobility inversely proportional to carrier density, indicating dominant weak scatterer scattering.

Observed a Bloch-Grüneisen regime up to 100 K at high densities.

Abstract

We report the study of graphene devices in Hall-bar geometry, gated with a polymer electrolyte. High densities of 6 $\times 10^{13}/cm^{2}$ are consistently reached, significantly higher than with conventional back-gating. The mobility follows an inverse dependence on density, which can be correlated to a dominant scattering from weak scatterers. Furthermore, our measurements show a Bloch-Gr\"uneisen regime until 100 K (at 6.2 $\times10^{13}/cm^{2}$), consistent with an increase of the density. Ubiquitous in our experiments is a small upturn in resistivity around 3 $\times10^{13}/cm^{2}$, whose origin is discussed. We identify two potential causes for the upturn: the renormalization of Fermi velocity and an electrochemically-enhanced scattering rate.