title: Air-stable transport in graphene-contacted, fully encapsulated ultrathin black phosphorus-based field-effect transistors.
abstract: The presence of direct bandgap and high mobility in semiconductor few-layer black phosphorus offers an attractive prospect for using this material in future two-dimensional electronic devices. However, creation of barrier-free contacts which is necessary to achieve high performance in black phosphorus-based devices is challenging and currently limits their potential for applications. Here, we characterize fully encapsulated ultrathin (down to bilayer) black phosphorus field effect transistors fabricated under inert gas conditions by utilizing graphene as source-drain electrodes and boron nitride as an encapsulation layer. The observation of a linear ISD-VSD behavior with negligible temperature dependence shows that graphene electrodes lead to barrier-free contacts, solving the issue of Schottky barrier limited transport in the technologically relevant two-terminal field-effect transistor geometry. Such one-atom-thick conformal source-drain electrodes also enable the black phosphorus surface to be sealed, to avoid rapid degradation, with the inert boron nitride encapsulating layer. This architecture, generally applicable for other sensitive two-dimensional crystals, results in air-stable, hysteresis-free transport characteristics.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Avsar
authors.affiliation: ‡Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
authors.forename: Ivan J
authors.initials: IJ
authors.lastname: Vera-Marun
authors.forename: Jun You
authors.initials: JY
authors.lastname: Tan
authors.affiliation: ∥National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: ∥National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Antonio H
authors.initials: AH
authors.lastname: Castro Neto
authors.affiliation: |Nanocore, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Özyilmaz
keywords: Schottky barrier; black phosphorus; boron nitride encapsulation; graphene electrode; hysteresis; ohmic contact; work function