Electrical Control of Optical Properties of Monolayer MoS$_2$

TL;DR

This study demonstrates that applying an external gate voltage can significantly enhance the photoluminescence and absorption in monolayer MoS$_2$, revealing a method to electrically control its optical properties, unlike bilayer MoS$_2$.

Contribution

It provides the first detailed analysis of electrical gating effects on optical properties of monolayer MoS$_2$, highlighting the role of exciton-charge interactions.

Findings

Photoluminescence in monolayer MoS$_2$ increases hundredfold with gate voltage.

Absorption at ~660 nm increases as gate voltage decreases.

Bilayer MoS$_2$ shows negligible change in photoluminescence with gating.

Abstract

We investigate electrical gating of photoluminescence and optical absorption in monolayer molybdenum disulfide (MoS$_2$) configured in field effect transistor geometry. We observe an hundredfold increase in photoluminescence intensity and an increase in absorption at ~660 nm in these devices when an external gate voltage is decreased from +50 V to -50 V, while the photoluminescence wavelength remains nearly constant. In contrast, in bilayer MoS$_2$ devices we observe almost no changes in photoluminescence with gate voltage. We propose that the differing responses of the monolayer and bilayer devices are related to the interaction of the excitons in MoS$_2$ with charge carriers.