title: Rotationally Commensurate Growth of MoS2 on Epitaxial Graphene.
abstract: Atomically thin MoS2/graphene heterostructures are promising candidates for nanoelectronic and optoelectronic technologies. Among different graphene substrates, epitaxial graphene (EG) on SiC provides several potential advantages for such heterostructures, including high electronic quality, tunable substrate coupling, wafer-scale processability, and crystalline ordering that can template commensurate growth. Exploiting these attributes, we demonstrate here the thickness-controlled van der Waals epitaxial growth of MoS2 on EG via chemical vapor deposition, giving rise to transfer-free synthesis of a two-dimensional heterostructure with registry between its constituent materials. The rotational commensurability observed between the MoS2 and EG is driven by the energetically favorable alignment of their respective lattices and results in nearly strain-free MoS2, as evidenced by synchrotron X-ray scattering and atomic-resolution scanning tunneling microscopy (STM). The electronic nature of the MoS2/EG heterostructure is elucidated with STM and scanning tunneling spectroscopy, which reveals bias-dependent apparent thickness, band bending, and a reduced band gap of ∼0.4 eV at the monolayer MoS2 edges.
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Itamar
authors.initials: I
authors.lastname: Balla
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Hadallia
authors.initials: H
authors.lastname: Bergeron
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Gavin P
authors.initials: GP
authors.lastname: Campbell
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bedzyk
authors.affiliation: Graduate Program in Applied Physics, ‡Department of Materials Science and Engineering, §Department of Physics, ∥Department of Chemistry, and ⊥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
keywords: chemical vapor deposition; scanning tunneling microscopy; silicon carbide; synchrotron X-ray scattering; transition metal dichalcogenide; van der Waals heterostructure