title: Graphene field effect transistors with niobium contacts and asymmetric transfer characteristics.
abstract: We fabricate back-gated field effect transistors using niobium electrodes on mechanically exfoliated monolayer graphene and perform electrical characterization in the pressure range from atmospheric down to 10(-4) mbar. We study the effect of room temperature vacuum degassing and report asymmetric transfer characteristics with a resistance plateau in the n-branch. We show that weakly chemisorbed Nb acts as p-dopant on graphene and explain the transistor characteristics by Nb/graphene interaction with unpinned Fermi level at the interface.
authors.affiliation: Dipartimento di Fisica 'E.R. Caianiello' and Centro Interdipartimentale NanoMates, Università degli Studi di Salerno, Fisciano, Salerno, Italy. CNR-SPIN, Fisciano, Salerno, Italy.
authors.forename: Antonio Di
authors.initials: AD
authors.lastname: Bartolomeo
authors.forename: Filippo
authors.initials: F
authors.lastname: Giubileo
authors.forename: Francesco
authors.initials: F
authors.lastname: Romeo
authors.forename: Paolo
authors.initials: P
authors.lastname: Sabatino
authors.forename: Giovanni
authors.initials: G
authors.lastname: Carapella
authors.forename: Laura
authors.initials: L
authors.lastname: Iemmo
authors.forename: Thomas
authors.initials: T
authors.lastname: Schroeder
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Lupina