Quenching the band gap of 2D semiconductors with a perpendicular electric field

TL;DR

This paper demonstrates a method to precisely control and reduce the band gap of 2D semiconductors using high electric fields enabled by double ionic gated transistors, opening new avenues for electronic applications.

Contribution

The study introduces double ionic gated transistors that allow for the application of large electric fields to tune the band gap of 2D semiconductors, achieving continuous suppression from 1.5 eV to zero.

Findings

Band gap of 2D semiconductors can be tuned from 1.5 eV to zero.

Double ionic gating enables application of high electric fields.

Continuous control of electronic properties in 2D materials.

Abstract

The electronic band structure of atomically thin semiconductors can be tuned by the application of a perpendicular electric field. The principle was demonstrated experimentally shortly after the discovery of graphene by opening a finite band gap in graphene bilayers, which naturally are zero-gap semiconductors. So far, however, the same principle could not be employed to control a broader class of materials, because the required electric fields are beyond reach in current devices. To overcome this limitation, we have realized double ionic gated transistors that enable the application of very large electric fields. Using these devices, we show that the band gap of few-layer semiconducting transition metal dichalcogenides can be continuously suppressed from 1.5 eV to zero. Our results illustrate an unprecedented level of control of the band structures of 2D semiconductors, which is important for future research and applications.