title: Electron Doping of Ultrathin Black Phosphorus with Cu Adatoms.
abstract: Few-layer black phosphorus is a monatomic two-dimensional crystal with a direct band gap that has high carrier mobility for both holes and electrons. Similarly to other layered atomic crystals, like graphene or layered transition metal dichalcogenides, the transport behavior of few-layer black phosphorus is sensitive to surface impurities, adsorbates, and adatoms. Here we study the effect of Cu adatoms onto few-layer black phosphorus by characterizing few-layer black phosphorus field effect devices and by performing first-principles calculations. We find that the addition of Cu adatoms can be used to controllably n-dope few layer black phosphorus, thereby lowering the threshold voltage for n-type conduction without degrading the transport properties. We demonstrate a scalable 2D material-based complementary inverter which utilizes a boron nitride gate dielectric, a graphite gate, and a single bP crystal for both the p- and n-channels. The inverter operates at matched input and output voltages, exhibits a gain of 46, and does not require different contact metals or local electrostatic gating.
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Koenig
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore , 28 Medical Drive, Singapore 117456, Singapore.
authors.forename: Rostislav A
authors.initials: RA
authors.lastname: Doganov
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: Leandro
authors.initials: L
authors.lastname: Seixas
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carvalho
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
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.affiliation: Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research , 2 Fusionopolis Way, Singapore 138634, Singapore.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Yakovlev
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore , 28 Medical Drive, Singapore 117456, Singapore.
authors.forename: Antonio H
authors.initials: AH
authors.lastname: Castro Neto
authors.affiliation: Centre for Advanced 2D Materials, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore , 28 Medical Drive, Singapore 117456, Singapore.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Özyilmaz
keywords: Phosphorene; adatoms; black phosphorus; doping; inverter; transistor