title: Layer-dependent modulation of tungsten disulfide photoluminescence by lateral electric fields.
abstract: Large single-crystal domains of WS2 are grown by chemical vapor deposition, and their photoluminescent properties under a lateral electric field are studied. We demonstrate that monolayer and bilayer WS2 have opposite responses to lateral electric fields, with WS2 photoluminescence (PL) substantially reduced in monolayer and increased in bilayers with increasing lateral electric field strength. Temperature-dependent PL measurements are also undertaken and show behavior distinctly different than that of the lateral electric field effects, ruling out heating as the cause of the PL changes. The PL variation in both monolayer and bilayer WS2 is attributed to the transfer of photoexcited electrons from one conduction band extremum to another, modifying the resultant recombination pathways. This effect is observed in 2D transition metal dichalcogenides due to their large exciton binding energy and small energy difference between the two conduction band extrema.
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: He
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
authors.forename: Yuewen
authors.initials: Y
authors.lastname: Sheng
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
authors.forename: Youmin
authors.initials: Y
authors.lastname: Rong
authors.affiliation: ‡Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Gun-Do
authors.initials: GD
authors.lastname: Lee
authors.forename: Ju
authors.initials: J
authors.lastname: Li
authors.affiliation: †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
authors.forename: Jamie H
authors.initials: JH
authors.lastname: Warner
keywords: 2D crystals; WS2; optoelectronics; photoluminescence; transition metal dichalcogenides; tungsten disulfide