High performance Broadband Photodetection Based on Graphene -- MoS$_{2x}$Se$_{2(1-x)}$ Alloy Engineered Phototransistors

TL;DR

This paper reports the development of a high-performance broadband photodetector using graphene combined with MoS$_{2x}$Se$_{2(1-x)}$ alloys, demonstrating superior optoelectronic properties and scalable fabrication methods.

Contribution

It introduces a novel alloy engineering approach to tune bandgap and defect levels in TMDCs for enhanced photodetector performance.

Findings

Graphene-MoSSe hybrid phototransistor shows >10^4 A/W responsivity.

Device achieves low noise (~10^-14 W/Hz^0.5) and high detectivity (~10^11 Jones).

Broadband detection from UV to NIR (365-810 nm).

Abstract

The concept of alloy engineering has emerged as a viable technique towards tuning the bandgap as well as engineering the defect levels in two-dimensional transition metal dichalcognides (TMDC). Possibility to synthesize these ultrathin TMDC materials through chemical route has opened realistic possibilities to fabricate hybrid multi-functional devices. By synthesizing nanosheets with different composites of MoS$_{2x}$Se$_{2(1-x)}$ (x = 0 to 1) using simple chemical methods, we systematically investigate the photo response properties of three terminal hybrid devices by decorating large area graphene with these nanosheets (x = 0, 0.5, 1) in 2D-2D configurations. Among them, graphene-MoSSe hybrid phototransistor exhibits superior optoelectronic properties than its binary counterparts. The device exhibits extremely high photoresponsivity (>10$^4$ A/W), low noise equivalent power (~10$^{-14}$ W/Hz$^{0.5}$), higher specific detectivity (~ 10$^{11}$ Jones) in the wide UV-NIR (365-810 nm) range with excellent gate tunability. The broadband light absorption of MoSSe, ultrafast charge transport in graphene, along with controllable defect engineering in MoSSe makes this device extremely attractive. Our work demonstrates the large area scalability with wafer-scale production of MoS$_{2x}$Se$_{2(1-x)}$ alloys, having important implication towards facile and scalable fabrication of high-performance optoelectronic devices and providing important insights into the fundamental interactions between van-der-Waals materials.