Disorder From the Bulk Ionic Liquid in Electric Double Layer Transistors

TL;DR

This paper develops and validates a model showing that bulk ionic liquid disorder causes Coulomb scattering, limiting carrier mobility in ionic liquid gated devices, especially in graphene with hexagonal boron nitride.

Contribution

The paper introduces a model for Coulomb scattering from bulk ionic liquids and experimentally validates it in graphene devices with varying hBN thickness.

Findings

Bulk ionic liquid disorder dominates Coulomb scattering.

Disorder impacts carrier mobility in ionic liquid gated devices.

Model accurately predicts scattering effects in experiments.

Abstract

Ionic liquid gating has a number of advantages over solid-state gating, especially for flexible or transparent devices and for applications requiring high carrier densities. However, the large number of charged ions near the channel inevitably results in Coulomb scattering, which limits the carrier mobility in otherwise clean systems. We develop a model for this Coulomb scattering. We validate our model experimentally using ionic liquid gating of graphene across varying thicknesses of hexagonal boron nitride, demonstrating that disorder in the bulk ionic liquid often dominates the scattering.