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

2019 ◽  
Vol 8 (2) ◽  
pp. 261-267
Author(s):  
Marius Rodner ◽  
Manuel Bastuck ◽  
Andreas Schütze ◽  
Mike Andersson ◽  
Joni Huotari ◽  
...  

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.

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 13
Author(s):  
Panagiotis Mougkogiannis ◽  
Michael Turner ◽  
Krishna Persaud

Low power gas sensors with high sensitivity and selectivity are desired for many practical applications. Devices based on organic field effect transistors are promising because they can be fabricated at modest cost and are low power devices. Organic field effect transistors fabricated in bottom-gate bottom-contact configuration using the organic semiconductor [2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno] [3,2-b]thiophene) (DPP-T-TT) were systematically investigated to determine the response characteristics to a series of alkylamines and ammonia. The highest sensitivity was to dibutylamine with a limit of detection of 0.025 ppb, followed by n-butylamine, 0.056 ppb, and ammonia, 2.17 ppb. A model was constructed based on the Antoine equation that successfully allows the empirical prediction of the sensitivity and selectivity of the gas sensor to various analytes including amines and alcohols based on the Antoine C parameter and the heat of the vaporization of the analyte.


2010 ◽  
Vol 645-648 ◽  
pp. 987-990 ◽  
Author(s):  
Hiroshi Kono ◽  
Takuma Suzuki ◽  
Makoto Mizukami ◽  
Chiharu Ota ◽  
Shinsuke Harada ◽  
...  

Silicon carbide Double-Implanted Metal-Oxide-Semiconductor Field-Effect Transistors (DIMOSFETs) were fabricated on 4H-SiC (000-1) carbon face. The DIMOSFETs were characterized from room temperature to 250°C. At room temperature, they showed a specific on-resistance of 4.9 mΩcm2 at a gate bias of 20 V and a drain voltage of 1.0 V. The specific on-resistance taken at a drain current (Id) of 260 A/cm2 was 5.0 mΩcm2. The blocking voltage of this device was higher than 1360 V at room temperature. At 250°C, the specific on-resistance increased from 5.0 mΩcm2 to 12.5 mΩcm2 and the threshold voltage determined at Id = 26 mA/cm2 decreased from 5.5 V to 4.3 V.


2014 ◽  
Vol 778-780 ◽  
pp. 935-938 ◽  
Author(s):  
Hiroshi Kono ◽  
Masaru Furukawa ◽  
Keiko Ariyoshi ◽  
Takuma Suzuki ◽  
Yasunori Tanaka ◽  
...  

Silicon carbide double-implanted metal-oxide-semiconductor field-effect transistors (DIMOSFETs) were fabricated on 4H-SiC (000-1) carbon face. The effect of current spread layer (CSL) structure was studied. 1.9 mm × 1.9 mm DIMOSFETs were characterized from room temperature to 200°C. At room temperature, the specific on-resistance of this MOSFET was 14.8 mΩcm2 at a gate bias of 20 V and a drain voltage of 0.5 V. The blocking voltage of this MOSFET was 3300 V. At 300 °C, the specific on-resistance increased from 14.8 mΩcm2 to 83.9 mΩcm2 and the threshold voltage decreased from 5.3 V to 3.4 V.


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