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 × 10 cm . 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 A C 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.

Twistronics: a turning point in 2D quantum materials

“…[14][15][16] Additionally, an emerging field of quasi-2D materials, such as Fe3GeTe2, Ni3GeTe2, and perovskites, have shown promise to be stable in monolayer morphology. [17][18][19] Monolayer materials have made contributions to fields as diverse as sensors (optical, bio, chemical, strain), [20][21][22][23][24][25][26] spin current injection, 27 massless resonators, 28 neural interfaces, 29,30 neural scaffolds, 31,32 singleion detection, 22 DNA/RNA sequencing and protein characterization, 25 low-cost organic solar cells, 33 single-photon emitters, 34 LEDs, [35][36][37] superconductivity, 38,39 transistors, [40][41][42] piezoelectrics, 43 and magnetism. 44 Although a definitive definition of 2D materials has not been established, most 2D materials are few-atom-thick and their properties can be described by quasiparticle excitations confined in two dimensions (i.e.…”

Ultrasensitive vapor phase ion detection by one dimensional and two-dimensional nanomaterials

“…But for gas pressure sensors, the researchers normally utilized the carbon nanotube and graphene as the cathode, due to their excellent field emission abilities, to substitute the filament in the conventional ionization gauge to generate electrons, this method can apparently help shrink the size of the pressure sensor, but it still need high applied voltage (more than 100V) to realize the electron emission [140][141][142]. Based on our former experimental results, the sample two terminal devices based carbon nanotube and graphene with very low applied voltages are very sensitive to charged gas molecules with possible single ion detection ability [112], so here we want to present that the SWNT and graphene devices can be used as the pressure sensor to monitor the low pressure of the vacuum chamber through sensing the ionized gas molecules generated by ionization gauge. Due to they're very highly sensitive to ionized gas molecules under very low voltage, which will pave a new way to help dramatically shrink the size and power consumption comparing to the conventional ionization gauge.…”

“…And we also first demonstrate the pressure sensing both at low pressure and atmospheric pressure by carbon nanotube and graphene sensors. For pressure sensing experiments, we use the SWNT/graphene device with the simple twoterminal structure as is shown in Figure 64 schematically depicts the set-up for the pressure sensing experiments, the vacuum pressure was pumped by a turbo system and mechanical pump, and a commercial ionization gauge was used as the pressure sensor and ion source to generate the positively ionized gas molecules [112]. The ion gauge was physically separated from the SWNT/ graphene detector by a narrow tube with a fixed distance.…”

“…When the high energy radiation passes through the air, the gas molecules in the air will be ionized to the charged gas molecules, which also can be detected by ion detectors, this is one of the common method people used to monitor the radiations from radioactive materials or other sources [4,16]. Since SWNT and graphene detectors are very sensitive to the charged particles [112], we can also use them to sense the radiation indirectly. Figure 69 shows the system we design to detect radiations, the SWNT or graphene device is sealed in the capsule with the gas, such as Air, N2, Xe, He, Ar etc.…”

Tunable electronic and optical properties of layered 2D materials

“…Ideally high carrier concentrations would be achievable with a simple back gate geometry. However due to the unstable nature of dielectrics at high gate voltages this is not possible.In this work we expand on a novel technique, initially reported in our previous work87 , for achieving high induced carrier concentrations in an arbitrary 2D material system through the electrostatic attachment of ionized gas molecules to the surface. This technique requires no additional lithography beyond what is needed for basic field effect devices and leaves the channel unobstructed for optical measurements.…”