title: Graphene contacts to a HfSe2/SnS2heterostructure.
abstract: Two-dimensional (2D) heterostructures and all-2D contacts are of high interest for electronic device applications, and the SnS2/HfSe2bilayer heterostructure with graphene contacts has some unique, advantageous properties. The SnS2/HfSe2heterostructure is interesting because of the strong intermixing of the two conduction bands and the large work function of the SnS2. The band lineup of the well separated materials indicates a type II heterostructure, but the conduction band minimum of the SnS2/HfSe2bilayer is a coherent superposition of the orbitals from the two layers with a spectral weight of 60% on the SnS2and 40% on the HfSe2for AA stacking. These relative weights can be either increased or reversed by an applied vertical field. A 3×3 supercell of graphene and a 2×2 supercell of SnS2/HfSe2have a lattice mismatch of 0.1% and both the SnS2/HfSe2conduction band at M and the graphene Dirac point at K are zone-folded to Γ. Placing graphene on the SnS2/HfSe2bilayer results in large n-type charge transfer doping of the SnS2/HfSe2bilayer, on the order of 1013/cm2, and the charge transfer is accompanied by a negative Schottky barrier contact for electron injection from the graphene into the SnS2/HfSe2bilayer conduction band. Binding energies and the anti-crossing gaps of the graphene and the SnS2/HfSe2electronic bands both show that the coupling of graphene to the HfSe2layer is significantly larger than its coupling to the SnS2layer. A tunneling Hamiltonian estimate of the contact resistance of the graphene to the SnS2/HfSe2heterostructure predicts an excellent low-resistance contact.
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA.
authors.forename: Shanshan
authors.identifier: 0000000262050084
authors.initials: S
authors.lastname: Su
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA.
authors.forename: Protik
authors.initials: P
authors.lastname: Das
authors.affiliation: Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
authors.forename: Supeng
authors.identifier: 0000000234861525
authors.initials: S
authors.lastname: Ge
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA.
authors.forename: Roger K
authors.initials: RK
authors.lastname: Lake