Lateral Graphene-Contacted Vertically Stacked WS2 /MoS2 Hybrid Photodetectors with Large Gain

Haijie Tan; Wenshuo Xu; Yuewen Sheng; Chit Siong Lau; Ye Fan; Qu Chen; Martin Tweedie; Xiaochen Wang; Yingqiu Zhou; Jamie H Warner

doi:10.1002/adma.201702917

Lateral Graphene-Contacted Vertically Stacked WS₂ /MoS₂ Hybrid Photodetectors with Large Gain

Adv Mater. 2017 Dec;29(46). doi: 10.1002/adma.201702917. Epub 2017 Oct 17.

Authors

Affiliations

¹ Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
² Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore, 138634, Republic of Singapore.

PMID: 29044833
DOI: 10.1002/adma.201702917

Abstract

A demonstration is presented of how significant improvements in all-2D photodetectors can be achieved by exploiting the type-II band alignment of vertically stacked WS₂ /MoS₂ semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS₂ /MoS₂ heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS₂ and MoS₂ , reaching 10³ A W^-1 under an illumination power density of 1.7 × 10² mW cm^-2 . The massive improvement in performance is due to the strong Coulomb interaction between WS₂ and MoS₂ layers. The efficient charge transfer at the WS₂ /MoS₂ heterointerface and long trapping time of photogenerated charges contribute to the observed large photoconductive gain of ≈3 × 10⁴ . Laterally spaced graphene electrodes with vertically stacked 2D van der Waals heterostructures are employed for making high-performing ultrathin photodetectors.

Keywords: MoS2; WS2; charge transfer; heterostructures; photodetectors.