Vapor‐Phase‐Gating‐Induced Ultrasensitive Ion Detection in Graphene and Single‐Walled Carbon Nanotube Networks. Issue 23 (10th April 2017)

• Record Type: Journal Article
• Authors: Hao, Ji; Li, Bo; Jung, Hyun Young; Liu, Fangze; Hong, Sanghyun; Jung, Yung Joon; Kar, Swastik
• Is Part Of: Advanced materials. Volume 29:Issue 23(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-04-10
• Subjects: carbon nanotubes -- gating -- graphene -- ion detection -- radiation sensors; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201606883
• Languages: English
• ISSNs: 0935-9648

Abstract

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 × 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. Abstract : Two‐terminal graphene/single‐walled carbon nanotube devices are extremely sensitive to incident vapor‐phase ions. These ions can gate‐modulate carrier densities up to ≈0.6 × 10 13 cm −2 . The detectors demonstrate charge–current amplification factors exceeding 10 8 A C −1 in vacuum and air, and distinguish positive and negative ions. At extremely low rates of ion incidence, the detector currents show step‐wise changes with time that may result from the arrival of single ions.