title: Postgrowth tuning of the bandgap of single-layer molybdenum disulfide films by sulfur/selenium exchange.
abstract: We demonstrate bandgap tuning of a single-layer MoS2 film on SiO2/Si via substitution of its sulfur atoms by selenium through a process of gentle sputtering, exposure to a selenium precursor, and annealing. We characterize the substitution process both for S/S and S/Se replacement. Photoluminescence and, in the latter case, X-ray photoelectron spectroscopy provide direct evidence of optical band gap shift and selenium incorporation, respectively. We discuss our experimental observations, including the limit of the achievable bandgap shift, in terms of the role of stress in the film as elucidated by computational studies, based on density functional theory. The resultant films are stable in vacuum, but deteriorate under optical excitation in air.
authors.affiliation: Chemistry, Physics, Electrical Engineering and Materials Science and Engineering, University of California , Riverside, California 92521, United States.
authors.forename: Quan
authors.initials: Q
authors.lastname: Ma
authors.forename: Miguel
authors.initials: M
authors.lastname: Isarraraz
authors.forename: Chen S
authors.initials: CS
authors.lastname: Wang
authors.forename: Edwin
authors.initials: E
authors.lastname: Preciado
authors.forename: Velveth
authors.initials: V
authors.lastname: Klee
authors.forename: Sarah
authors.initials: S
authors.lastname: Bobek
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Emily
authors.initials: E
authors.lastname: Li
authors.forename: Patrick Michael
authors.initials: PM
authors.lastname: Odenthal
authors.forename: Ariana
authors.initials: A
authors.lastname: Nguyen
authors.forename: David
authors.initials: D
authors.lastname: Barroso
authors.forename: Dezheng
authors.initials: D
authors.lastname: Sun
authors.forename: Gretel
authors.initials: G
authors.lastname: von Son Palacio
authors.forename: Michael
authors.initials: M
authors.lastname: Gomez
authors.forename: Andrew
authors.initials: A
authors.lastname: Nguyen
authors.forename: Duy
authors.initials: D
authors.lastname: Le
authors.forename: Greg
authors.initials: G
authors.lastname: Pawin
authors.forename: John
authors.initials: J
authors.lastname: Mann
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: Talat Shahnaz
authors.initials: TS
authors.lastname: Rahman
authors.forename: Ludwig
authors.initials: L
authors.lastname: Bartels