UV Illumination as a Method to Improve the Performance of Gas Sensors Based on Graphene Field-Effect Transistors

AbstractThe first paper showing the great potentiality of Carbon Nanotubes Field Effect transistors (CNTFETs) for gas sensing applications was published in 2000 [1]. It has been demonstrated that the performances of this kind of sensors are extremely interesting: a sensitivity of around 100ppt (e.g. for NO2 [2]) has been achieved in 2003 and several techniques to improve selectivity have been tested with very promising results [2]. The main issues that have not allowed, up to now, these devices to strike more largely the market of sensors, have been the lack of an industrial method to obtain low-cost devices, a demonstration of their selectivity in relevant environments and finally a deeper study on the effect of humidity and the possible solutions to reduce it. This contribution deals with CNTFETs based sensors fabricated using air-brush technique deposition on large surfaces. Compared to our last contribution [3], we have optimized the air-brush technique in order to obtain high performances transistors (Log(Ion)/Log(Ioff) ∼ 5/6) with highly reproducible characteristics : this is a key point for the industrial exploitation. We have developed a machine which allows us the dynamic deposition on heated substrates of the SWCNT solutions, improving dramatically the uniformity of the SWCNT mats. We have performed tests using different solvents that could be adapted as a function of the substrates (e.g. flexible substrates). Moreover these transistors have been achieved using different metal electrodes (patented approach [4]) in order to improve selectivity. Results of tests using NO2, NH3 with concentrations between ∼ 1ppm and 10ppm will be shown during the meeting.

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Enabling a new method of dynamic field-effect gas sensor operation through lithium-doped tungsten oxide

Journal of Sensors and Sensor Systems ◽

10.5194/jsss-8-261-2019 ◽

2019 ◽

Vol 8 (2) ◽

pp. 261-267

Author(s):

Marius Rodner ◽

Manuel Bastuck ◽

Andreas Schütze ◽

Mike Andersson ◽

Joni Huotari ◽

...

Keyword(s):

Gas Sensors ◽

Field Effect ◽

Field Effect Transistors ◽

Relaxation Effect ◽

Oxide Semiconductor ◽

Transient Signal ◽

Gate Bias ◽

Sensitivity And Selectivity ◽

Increased Sensitivity ◽

Novel Method

Abstract. To fulfil today's requirements, gas sensors have to become more and more sensitive and selective. Temperature-cycled operation has long been used to enhance the sensitivity and selectivity of metal-oxide semiconductor gas sensors and, more recently, silicon-carbide-based, gas-sensitive field-effect transistors (SiC-FETs). In this work, we present a novel method to significantly enhance the effect of gate bias on a SiC-FET's response, giving rise to new possibilities for static and transient signal generation and, thus, increased sensitivity and selectivity. A tungsten trioxide (WO3) layer is deposited via pulsed laser deposition as an oxide layer beneath a porous iridium gate, and is doped with 0.1 AT % of lithium cations. Tests with ammonia as a well-characterized model gas show a relaxation effect with a time constant between 20 and 30 s after a gate bias step as well as significantly increased response and sensitivity at +2 V compared to 0 V. We propose an electric field-mediated change in oxygen surface coverage as the cause of this novel effect.

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Dielectrics & Electrostatics: Their Effect on Carbon Nanotube Network Field-Effect Transistors and Gas Sensors

ECS Meeting Abstracts ◽

10.1149/ma2018-01/7/743 ◽

2018 ◽

Keyword(s):

Carbon Nanotube ◽

Gas Sensors ◽

Field Effect ◽

Field Effect Transistors ◽

Carbon Nanotube Network

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Metal-oxide Semiconductor Field-effect Transistors using Single ZnO Nanowire

MRS Proceedings ◽

10.1557/proc-829-b8.1 ◽

2004 ◽

Vol 829 ◽

Author(s):

Young-Woo Heo ◽

B. S. Kang ◽

L. C. Tien ◽

Y. Kwon ◽

J. R. La Roche ◽

...

Keyword(s):

Metal Oxide ◽

Field Effect ◽

Field Effect Transistors ◽

Ultra Violet ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Zno Nanowire ◽

Current Increase ◽

Uv Illumination ◽

Source Current

ABSTRACTSingle ZnO nanowire metal-oxide semiconductor field effect transistors (MOSFETs) were fabricated using nanowires grown by site selective Molecular Beam Epitaxy. When measured in the dark at 25°C, the depletion-mode transistors exhibit good saturation behavior, a threshold voltage of ∼-3V and a maximum transconductance of order 0.3 mS/mm. Under ultra-violet (366nm) illumination, the drain-source current increase by approximately a factor of 5 and the maximum transconductance is ∼ 5 mS/mm. The channel mobility is estimated to be ∼3 cm2 /V.s, which is comparable to that reported for thin film ZnO enhancement mode MOSFETs and the on/off ratio was ∼25 in the dark and ∼125 under UV illumination.

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UV Illumination as a Method to Improve the Performance of Gas Sensors Based on Graphene Field-Effect Transistors

Gas sensors-based on field-effect transistors

Distinct characteristics of DNA field effect transistors embedded with marine-derived porphyra-334 under UV illumination

Phthalocyanine-based field-effect transistors as gas sensors

High-performance diketopyrrolopyrrole-based organic field-effect transistors for flexible gas sensors

Gate modulation in carbon nanotube field effect transistors-based NH3 gas sensors

Solution-Processed Monolayer Organic Crystals for High-Performance Field-Effect Transistors and Ultrasensitive Gas Sensors

CNTFET Gas Sensors Using SWCNT Mats: Method for Low-cost Fabrication, Solution to Improve Selectivity, Experimental Results using Interfering Agents

Enabling a new method of dynamic field-effect gas sensor operation through lithium-doped tungsten oxide

Dielectrics & Electrostatics: Their Effect on Carbon Nanotube Network Field-Effect Transistors and Gas Sensors

Metal-oxide Semiconductor Field-effect Transistors using Single ZnO Nanowire

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