Ultrasensitive all-2D MoS2 phototransistors enabled by an out-of-plane MoS2 PN homojunction

Nengjie Huo,Gerasimos Konstantatos

doi:10.1038/s41467-017-00722-1

Nengjie Huo, Gerasimos Konstantatos

Open Access

https://doi.org/10.1038/s41467-017-00722-1

Copy DOI

Abstract

Two-dimensional transition metal dichalcogenide-based photodetectors have demonstrated potential for the next generation of 2-dimensional optoelectronics. However, to date, their sensitivity has not been superior to that of other technologies. Here we report an ultrasensitive two-dimensional photodetector employing an in-plane phototransistor with an out-of-plane vertical MoS2 p–n junction as a sensitizing scheme. The vertical built-in field is introduced for the first time in the transport channel of MoS2 phototransistors by facile chemical surface doping, which separates the photo-excited carriers efficiently and produces a photoconductive gain of >105 electrons per photon, external quantum efficiency greater than 10%, responsivity of 7 × 104 A W−1, and a time response on the order of tens of ms. This taken together with a very low noise power density yields a record sensitivity with specific detectivity D^* of 3.5 × 1014 Jones in the visible and a broadband response up to 1000 nm.

Highlights

Two-dimensional transition metal dichalcogenide-based photodetectors have demonstrated potential for the generation of 2-dimensional optoelectronics
Many efforts have been made to develop transition metal dichalcogenides (TMDs) 2D-based photodetectors with ultrafast response[17] and high responsivity[11], with a view to enable their widespread application in remote sensing, camera imaging and optical communications
TMDs-based photodiodes with p–n junctions have been fabricated with transferred van der Waals heterostructures[18] or chemical vapor deposition grown hybrids[19]; they are characterized by low responsivity due to the absence of a photo-gain mechanism or by persistent photoconductivity which is unsuitable for photodetector applications

Summary

Introduction

Two-dimensional transition metal dichalcogenide-based photodetectors have demonstrated potential for the generation of 2-dimensional optoelectronics. The internal built-in field created from the p–n junction facilitates the photo-excited carrier separation and leads to a significant photo-gating effect As a result this hybrid detector yields a responsivity of 7 × 104 A W−1 and a record measured detectivity of 3.5 × 1014 Jones with a time response on the order of 10 ms demonstrating the highest sensitivity of 2D-based photodetector to date[11, 24,25,26,27,28,29,30,31,32,33,34,35]

Methods

Results

Conclusion