Quantum Capacitance Induced Non-Local Electrostatic Gating Effect in Graphene

TL;DR

This paper demonstrates a non-local electrostatic gating effect in graphene, where a remote gate over 30 micrometers away can efficiently tune charge density, enabled by quantum capacitance and water molecule-assisted screening.

Contribution

It reveals a novel non-local gating mechanism in graphene driven by quantum capacitance and water-assisted electric field screening, enabling remote control of electronic properties.

Findings

Charge density of graphene can be tuned remotely over 30 μm.

Non-local gating is driven by in-plane electric fields near the Dirac point.

Absorbed water molecules amplify the non-local effect through screening.

Abstract

Electrostatic gating lies in the heart of modern FET-based integrated circuits. Usually, the gate electrode has to be placed very close to the conduction channel, typically a few nanometers, in order to achieve efficient tunability. However, remote control of a FET device through a gate electrode placed far away is always highly desired, because it not only reduces the complexity of device fabrication, but also enables designing novel devices with new functionalities. Here, a non-local gating effect in graphene using both near-field optical nano-imaging and electrical transport measurement is reported. With assistance of absorbed water molecules, the charge density of graphene can be efficiently tuned by a local-gate placed over 30 {\mu}m away. The observed non-local gating effect is initially driven by an in-plane electric field established between graphene regions with different charge densities due to the quantum capacitance near the Dirac point in graphene. The nonlocality is further amplified and largely enhanced by absorbed water molecules through screening the in-plane electric field and expending the transition length. This research reveals novel non-local phenomenon of Dirac electrons, and paves the way for designing electronic devices with remote-control using 2D materials with small density of states.