title: Oxidized titanium as a gate dielectric for graphene field effect transistors and its tunneling mechanisms.
abstract: We fabricate and characterize a set of dual-gated graphene field effect transistors using a novel physical vapor deposition technique in which titanium is evaporated onto the graphene channel in 10 Å cycles and oxidized in ambient to form a top-gate dielectric. A combination of X-ray photoemission spectroscopy, ellipsometry, and transmission electron microscopy suggests that the titanium is oxidizing in situ to titanium dioxide. Electrical characterization of our devices yields a dielectric constant of κ = 6.9 with final mobilities above 5500 cm(2)/(V s). Low temperature analysis of the gate-leakage current in the devices gives a potential barrier of 0.78 eV in the conduction band and a trap depth of 45 meV below the conduction band.
authors.affiliation: Microelectronics Research Center, The University of Texas at Austin , Austin, Texas 78758, United States.
authors.forename: Chris M
authors.initials: CM
authors.lastname: Corbet
authors.forename: Connor
authors.initials: C
authors.lastname: McClellan
authors.forename: Kyounghwan
authors.initials: K
authors.lastname: Kim
authors.forename: Sushant
authors.initials: S
authors.lastname: Sonde
authors.forename: Emanuel
authors.initials: E
authors.lastname: Tutuc
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Banerjee
keywords: dielectric; gate leakage; graphene; seed layer; titanium oxide; transistor