Quantitative Determination of the Band-Gap of WS2 with Ambipolar Ionic Liquid-Gated Transistors

TL;DR

This paper demonstrates a method to accurately measure the band-gap of WS2 using ambipolar ionic liquid-gated transistors, highlighting the potential of ionic liquids for precise electronic property analysis of nanomaterials.

Contribution

It introduces a novel approach employing ionic liquid-gated transistors to directly and precisely determine the band-gap of WS2, advancing nanoscale material characterization.

Findings

Achieved ideal electrical characteristics in WS2 transistors

Enabled high-precision band-gap measurement from gate-voltage dependence

Showed ionic liquids as effective tools for electronic property studies

Abstract

We realized ambipolar Field-Effect Transistors by coupling exfoliated thin flakes of tungsten disulphide (WS2) with an ionic liquid-dielectric. The devices show ideal electrical characteristics, including very steep sub-threshold slopes for both electrons and holes and extremely low OFF-state currents. Thanks to these ideal characteristics, we determine with high precision the size of the band-gap of WS2 directly from the gate-voltage dependence of the source-drain current. Our results demonstrate how a careful use of ionic liquid dielectrics offers a powerful strategy to study quantitatively the electronic properties of nano-scale materials.