title: Probing Interlayer Interactions in Transition Metal Dichalcogenide Heterostructures by Optical Spectroscopy: MoS2/WS2 and MoSe2/WSe2.
abstract: We have applied optical absorption spectroscopy to investigate van der Waals heterostructures formed of pairs of monolayer transition metal dichalcogenide crystals, choosing MoS2/WS2 and MoSe2/WSe2 as test cases. In the heterostructure spectra, we observe a significant broadening of the excitonic transitions compared to the corresponding features in the isolated layers. The broadening is interpreted as a lifetime effect arising from decay of excitons initially created in either layer through charge transfer processes expected for a staggered band alignment. The measured spectral broadening of 20 meV - 35 meV implies lifetimes for charge separation of the near band-edge A and B excitons in the range of 20-35 fs. Higher-lying transitions exhibit still greater broadening.
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States.
authors.forename: Albert F
authors.initials: AF
authors.lastname: Rigosi
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Hill
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States.
authors.forename: Alexey
authors.initials: A
authors.lastname: Chernikov
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, New York, New York 10027, United States.
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
mesh_terms: D004220:Disulfides / Q000737:chemistry*; D008982:Molybdenum / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry*; D012666:Semiconductors; D013057:Spectrum Analysis; D028561:Transition Elements / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: D004220:Disulfides; D018036:Selenium Compounds; D028561:Transition Elements; D017973:Tungsten Compounds; D008982:Molybdenum; C082964:molybdenum disulfide
keywords: 2D materials; charge transfer; heterostructures; lifetime broadening; transition metal dichalcogenides