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Vapor‐Phase‐Gating‐Induced Ultrasensitive Ion Detection in Graphene and Single‐Walled Carbon Nanotube Networks
Author(s) -
Hao Ji,
Li Bo,
Jung Hyun Young,
Liu Fangze,
Hong Sanghyun,
Jung Yung Joon,
Kar Swastik
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201606883
Subject(s) - materials science , carbon nanotube , optoelectronics , graphene , ion , conductance , detector , analytical chemistry (journal) , nanotechnology , optics , chemistry , physics , organic chemistry , chromatography , condensed matter physics
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 × 10 13 cm −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 10 8 A C −1 in 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.