Graphene transport at high carrier densities using a polymer electrolyte gate

¹ Department of Physics, National University of Singapore - 2 Science Drive 3, Singapore 117542
² NUS Graduate School for Integrative Sciences and Engineering (NGS) - Singapore 117456
³ Department of Chemistry, National University of Singapore - 3 Science Drive 3, Singapore 117543
⁴ Nanocore, National University of Singapore - 4 Engineering Drive 3, Singapore 117576

^b phyob@nus.edu.sg

Received: 16 September 2010
Accepted: 30 September 2010

Abstract

We report the study of graphene devices in Hall-bar geometry, gated with a polymer electrolyte. High densities of 6×10¹³/cm² 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-Grüneisen regime until 100 K (at 6.2×10¹³/cm²), consistent with an increase of the density. Ubiquitous in our experiments is a small upturn in resistivity around 3×10¹³/cm², whose origin is discussed. We identify two potential causes for the upturn: the renormalization of Fermi velocity and an electrochemically enhanced scattering rate.