Extrinsic Origin of Persistent Photoconductivity in Monolayer MoS2 Field Effect Transistors

TL;DR

This study reveals that persistent photoconductivity in monolayer MoS2 transistors is caused by extrinsic substrate-induced potential fluctuations, offering new ways to control and utilize this effect in optoelectronic devices.

Contribution

The paper provides a detailed analysis linking extrinsic substrate effects to persistent photoconductivity in monolayer MoS2, highlighting a novel control mechanism.

Findings

PPC in MoS2 is due to extrinsic substrate-induced potential fluctuations.

A correlation exists between PPC and percolation transport behavior.

Control of PPC can be achieved through substrate engineering.

Abstract

Recent discoveries of the photoresponse of molybdenum disulfide (MoS2) have shown the considerable potential of these two-dimensional transition metal dichalcogenides for optoelectronic applications. Among the various types of photoresponses of MoS2, persistent photoconductivity (PPC) at different levels has been reported. However, a detailed study of the PPC effect and its mechanism in MoS2 is still not available, despite the importance of this effect on the photoresponse of the material. Here, we present a systematic study of the PPC effect in monolayer MoS2 and conclude that the effect can be attributed to random localized potential fluctuations in the devices. Notably, the potential fluctuations originate from extrinsic sources based on the substrate effect of the PPC. Moreover, we point out a correlation between the PPC effect in MoS2 and the percolation transport behavior of MoS2. We demonstrate a unique and efficient means of controlling the PPC effect in monolayer MoS2, which may offer novel functionalities for MoS2-based optoelectronic applications in the future.