Irradiation Wavelength-Dependent Photocurrent Sensing Characteristics of AuNPs/P3HT Composites on Volatile Vapor

Many low-dimensional nanostructured metal oxides (MOXs) with impressive room-temperature gas-sensing characteristics have been synthesized, yet transforming them into relatively robust bulk materials has been quite neglected. Pt-decorated SnO2 nanoparticles with 0.25–2.5 wt% Pt were prepared, and highly attractive room-temperature hydrogen-sensing characteristics were observed for them all through pressing them into pellets. Some pressed pellets were further sintered over a wide temperature range of 600–1200 °C. Though the room-temperature hydrogen-sensing characteristics were greatly degraded in many samples after sintering, those samples with 0.25 wt% Pt and sintered at 800 °C exhibited impressive room-temperature hydrogen-sensing characteristics comparable to those of their counterparts of as-pressed pellets. The variation of room-temperature hydrogen-sensing characteristics among the samples was explained by the facts that the connectivity between SnO2 grains increases with increasing sintering temperature, and Pt promotes oxidation of SnO2 at high temperatures. These results clearly demonstrate that some low-dimensional MOX nanocrystals can be successfully transformed into bulk MOXs with improved robustness and comparable room-temperature gas-sensing characteristics.

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Performance Optimization of Nitrogen Dioxide Gas Sensor Based on Pd-AlGaN/GaN HEMTs by Gate Bias Modulation

Micromachines ◽

10.3390/mi12040400 ◽

2021 ◽

Vol 12 (4) ◽

pp. 400

Author(s):

Van Cuong Nguyen ◽

Kwangeun Kim ◽

Hyungtak Kim

Keyword(s):

Gas Sensors ◽

Performance Optimization ◽

Response Times ◽

High Electron Mobility Transistors ◽

High Electron ◽

Gate Bias ◽

High Electron Mobility ◽

Electron Mobility Transistors ◽

Gan Hemts ◽

Sensing Characteristics

We investigated the sensing characteristics of NO2 gas sensors based on Pd-AlGaN/GaN high electron mobility transistors (HEMTs) at high temperatures. In this paper, we demonstrated the optimization of the sensing performance by the gate bias, which exhibited the advantage of the FET-type sensors compared to the diode-type ones. When the sensor was biased near the threshold voltage, the electron density in the channel showed a relatively larger change with a response to the gas exposure and demonstrated a significant improvement in the sensitivity. At 300 °C under 100 ppm concentration, the sensor’s sensitivities were 26.7% and 91.6%, while the response times were 32 and 9 s at VG = 0 V and VG = −1 V, respectively. The sensor demonstrated the stable repeatability regardless of the gate voltage at a high temperature.

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Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics

Sensors ◽

10.3390/s21062103 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2103 ◽

Cited By ~ 1

Author(s):

Tae-Hee Han ◽

So-Young Bak ◽

Sangwoo Kim ◽

Se Hyeong Lee ◽

Ye-Ji Han ◽

...

Keyword(s):

Gas Sensor ◽

Gas Sensors ◽

Sol Gel ◽

Oxide Semiconductor ◽

Zno Nps ◽

X Ray ◽

Semiconductor Gas Sensor ◽

Initial Resistance ◽

P Type ◽

Sensing Characteristics

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

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