title: Exciton binding energy and nonhydrogenic Rydberg series in monolayer WS(2).
abstract: We have experimentally determined the energies of the ground and first four excited excitonic states of the fundamental optical transition in monolayer WS_{2}, a model system for the growing class of atomically thin two-dimensional semiconductor crystals. From the spectra, we establish a large exciton binding energy of 0.32 eV and a pronounced deviation from the usual hydrogenic Rydberg series of energy levels of the excitonic states. We explain both of these results using a microscopic theory in which the nonlocal nature of the effective dielectric screening modifies the functional form of the Coulomb interaction. These strong but unconventional electron-hole interactions are expected to be ubiquitous in atomically thin materials.
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Chernikov
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Berkelbach
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Hill
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Rigosi
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Ozgur Burak
authors.initials: OB
authors.lastname: Aslan
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Reichman
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Hybertsen
authors.affiliation: Departments of Physics and Electrical Engineering, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz