title: Vapor-Phase-Gating-Induced Ultrasensitive Ion Detection in Graphene and Single-Walled Carbon Nanotube Networks.
abstract: Designing ultrasensitive detectors often requires complex architectures, high-voltage operations, and sophisticated low-noise measurements. In this work, it is shown that simple low-bias two-terminal DC-conductance values of graphene and single-walled carbon nanotubes are extremely sensitive to ionized gas molecules. Incident ions form an electrode-free, dielectric- or electrolyte-free, bias-free vapor-phase top-gate that can efficiently modulate carrier densities up to ≈0.6 × 1013cm-2. Surprisingly, the resulting current changes are several orders of magnitude larger than that expected from conventional electrostatic gating, suggesting the possible role of a current-gain inducing mechanism similar to those seen in photodetectors. These miniature detectors demonstrate charge-current amplification factor values exceeding 108A C-1in vacuum with undiminished responses in open air, and clearly distinguish between positive and negative ions sources. At extremely low rates of ion incidence, detector currents show stepwise changes with time, and calculations suggest that these stepwise changes can result from arrival of individual ions. These sensitive ion detectors are used to demonstrate a proof-of-concept low-cost, amplifier-free, light-emitting-diode-based low-power ion-indicator.
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Hao
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.|Department of Mechanical Engineering, Villanova University, Villanova, PA, 19085, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.|Department of Energy Engineering, Gyeongnam National University of Science and Technology, Jinju-Si, Gyeongnam, 660-758, South Korea.
authors.forename: Hyun Young
authors.initials: HY
authors.lastname: Jung
authors.affiliation: Department of Physics, Northeastern University, Boston, MA, 02115, USA.|Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
authors.forename: Fangze
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Hong
authors.affiliation: Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA.
authors.forename: Yung Joon
authors.initials: YJ
authors.lastname: Jung
authors.affiliation: Department of Physics, Northeastern University, Boston, MA, 02115, USA.|Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, P. R. China.
authors.forename: Swastik
authors.identifier: http://orcid.org/0000-0001-6478-7082
authors.initials: S
authors.lastname: Kar
keywords: carbon nanotubes; gating; graphene; ion detection; radiation sensors