Evaluation of Disorder Introduced by Electrolyte Gating through Transport Measurements in Graphene

TL;DR

This study assesses how electrolyte gating introduces disorder in graphene by measuring transport properties, revealing ionic liquid deposition adds charged impurities and phonons further reduce mobility, impacting device performance.

Contribution

It provides quantitative analysis of disorder caused by electrolyte gating in graphene, highlighting impurity density and mobility limits at various temperatures.

Findings

Ionic liquid deposition introduces charged impurities of about 6×10^12 cm^-2.

Mobility limited to 3000 cm^2/Vs at low temperature, 2000 cm^2/Vs at room temperature.

Disorder effects are independent of the base material, applicable to various electrolyte-gated devices.

Abstract

We evaluate the degree of disorder in electrolyte gating devices through the transport measurements in graphene. By comparing the mobility in ion- and standard metal-gated devices, we show that the deposition of the ionic liquid introduces charged impurities with a density of approximately $6\times 10^{12}$ cm$^{-2}$; setting the upper limit of the mobility in graphene to 3000 cm$^2$/Vs. At higher temperature, phonons in the ionic liquid further reduce the mobility, making its upper limit 2000 cm$^2$/Vs at room temperature. Since the degree of disorder is independent of the base material, these results are valuable towards understanding disorder effects in general devices using electrolyte gating.