Nanocrystalline tungsten oxide thick-films with high sensitivity to H2S at room temperature

ABSTRACTWe demonstrate that one can detect minuscule amounts of hydrogen diffusion out of a-Si:H under illumination at room temperature, by monitoring the changes in the Raman spectrum of amorphous tungsten oxide as a function of illumination. The Staebler-Wronski effect, the light-induce creation of metastable defects in hydrogenated amorphous silicon (a-Si:H), has been one of the major problems that has limited the performance of such devices as solar cells. Recently, Branz suggested the hydrogen collision model that can explain many aspects of the Staebler-Wronski effect. One of the main predictions of this model is that the photogenerated mobile hydrogen atoms can move a long distance at room temperature. However, light-induced hydrogen motion in a-Si:H has not been experimentally observed at room temperature. We utilized the high sensitivity of the Raman spectrum of electrochromic a-WO3 to hydrogen insertion to probe the long-range motion of hydrogen at room temperature. We deposited a thin (200 nm) layer of a-WO3 on top of a-Si:H, and under illumination, a change in the Raman spectrum was detected. By comparing the Raman signal changes with those for control experiments where hydrogen is electrochemically inserted into a-WO3, we can estimate semiquantitatively the amount of hydrogen that diffuses out of the a-Si:H layer.

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UV-assisted High-sensitivity Room-temperature Pd-gated HEMT NO2Gas Sensor

2021 5th IEEE Electron Devices Technology & Manufacturing Conference (EDTM) ◽

10.1109/edtm50988.2021.9420958 ◽

2021 ◽

Author(s):

Chong Xing ◽

Dongcheng Xie ◽

Haochen Zhang ◽

Kang Song ◽

Lei Yang ◽

...

Keyword(s):

Room Temperature ◽

High Sensitivity

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Spatially Ordered Matrix of Nanostructured Tin–Tungsten Oxides Nanocomposites Formed by Ionic Layer Deposition for Gas Sensing

Sensors ◽

10.3390/s21124169 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4169

Author(s):

Gennady Gorokh ◽

Natalia Bogomazova ◽

Abdelhafed Taleb ◽

Valery Zhylinski ◽

Timur Galkovsky ◽

...

Keyword(s):

Tungsten Oxide ◽

Gas Sensing ◽

Oxide Films ◽

High Sensitivity ◽

Anodic Alumina ◽

Film Deposition ◽

Silicon Substrates ◽

Layer By Layer ◽

Gas Sensitivity ◽

Nanoporous Anodic Alumina

The process of layer-by-layer ionic deposition of tin-tungsten oxide films on smooth silicon substrates and nanoporous anodic alumina matrices has been studied. To achieve the film deposition, solutions containing cationic SnF2 or SnCl2 and anionic Na2WO4 or (NH4)2O·WO3 precursors have been used. The effect of the solution compositions on the films deposition rates, morphology, composition, and properties was investigated. Possible mechanisms of tin-tungsten oxide films deposition into the pores and on the surface of anodic alumina are discussed. The electro-physical and gas-sensitive properties of nanostructured SnxWyOz films have been investigated. The prepared nanocomposites exhibit stable semiconductor properties characterized by high resistance and low temperature coefficient of electrical resistance of about 1.6 × 10−3 K−1. The sensitivity of the SnxWyOz films to 2 and 10 ppm concentrations of ammonia at 523 K was 0.35 and 1.17, respectively. At concentrations of 1 and 2 ppm of nitrogen dioxide, the sensitivity was 0.48 and 1.4, respectively, at a temperature of 473 K. At the temperature of 573 K, the sensitivity of 1.3 was obtained for 100 ppm of ethanol. The prepared nanostructured tin-tungsten oxide films showed promising gas-sensitivity, which makes them a good candidate for the manufacturing of gas sensors with high sensitivity and low power consumption.

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Fabrication of Graphene Nanomesh FET Terahertz Detector

Micromachines ◽

10.3390/mi12060641 ◽

2021 ◽

Vol 12 (6) ◽

pp. 641

Author(s):

Yuan Zhai ◽

Yi Xiang ◽

Weiqing Yuan ◽

Gang Chen ◽

Jinliang Shi ◽

...

Keyword(s):

Room Temperature ◽

Energy Gap ◽

Coupling Efficiency ◽

High Sensitivity ◽

Fabrication Process ◽

Monolayer Graphene ◽

Terahertz Waves ◽

Wet Process ◽

Graphene Nanomesh ◽

Thz Detector

High sensitivity detection of terahertz waves can be achieved with a graphene nanomesh as grating to improve the coupling efficiency of the incident terahertz waves and using a graphene nanostructure energy gap to enhance the excitation of plasmon. Herein, the fabrication process of the FET THz detector based on the rectangular GNM (r-GNM) is designed, and the THz detector is developed, including the CVD growth and the wet-process transfer of high quality monolayer graphene films, preparation of r-GNM by electron-beam lithography and oxygen plasma etching, and the fabrication of the gate electrodes on the Si3N4 dielectric layer. The problem that the conductive metal is easy to peel off during the fabrication process of the GNM THz device is mainly discussed. The photoelectric performance of the detector was tested at room temperature. The experimental results show that the sensitivity of the detector is 2.5 A/W (@ 3 THz) at room temperature.

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Room temperature selective oxidation of aniline to azoxybenzene over a silver supported tungsten oxide nanostructured catalyst

Green Chemistry ◽

10.1039/c4gc02123a ◽

2015 ◽

Vol 17 (3) ◽

pp. 1867-1876 ◽

Cited By ~ 54

Author(s):

Shilpi Ghosh ◽

Shankha S. Acharyya ◽

Takehiko Sasaki ◽

Rajaram Bal

Keyword(s):

Silver Nanoparticles ◽

Tungsten Oxide ◽

Selective Oxidation ◽

Oxidative Coupling ◽

Room Temperature ◽

Heterogeneous Catalysts ◽

Nanostructured Catalyst ◽

Important Chemical

Heterogeneous catalysts comprising silver nanoparticles supported on nanostructured tungsten oxide were applied for room temperature oxidative coupling of aniline to azoxybenzene, an important chemical intermediate and a chemical of industrial interest.

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Novel room temperature carbon monoxide sensor utilizing rate of change of resistance in thick films of tin oxide

International Journal of Electronics ◽

10.1080/00207219408925983 ◽

1994 ◽

Vol 76 (5) ◽

pp. 815-820 ◽

Cited By ~ 6

Author(s):

E. W. WILLIAMS ◽

C. M. LAWLOR ◽

A. G. KEELING ◽

R. D. GOULD

Keyword(s):

Carbon Monoxide ◽

Tin Oxide ◽

Room Temperature ◽

Thick Films ◽

Rate Of Change ◽

Carbon Monoxide Sensor

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High sensitivity carbon monoxide sensors made by zinc oxide modified gated GaN/AlGaN high electron mobility transistors under room temperature

Applied Physics Letters ◽

10.1063/1.3596440 ◽

2011 ◽

Vol 98 (22) ◽

pp. 223504 ◽

Cited By ~ 21

Author(s):

S. C. Hung ◽

C. W. Chen ◽

C. Y. Shieh ◽

G. C. Chi ◽

R. Fan ◽

...

Keyword(s):

Carbon Monoxide ◽

Zinc Oxide ◽

Electron Mobility ◽

Room Temperature ◽

High Sensitivity ◽

High Electron Mobility Transistors ◽

High Electron ◽

High Electron Mobility ◽

Electron Mobility Transistors

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Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19446 ◽

2021 ◽

Vol 21 (10) ◽

pp. 5143-5149

Author(s):

Zhen Zhu ◽

Wang-De Lin

Keyword(s):

Room Temperature ◽

Response Times ◽

Sol Gel ◽

Hollow Spheres ◽

High Sensitivity ◽

Humidity Sensing ◽

X Ray ◽

Transmission Electron ◽

Recovery Times ◽

Relative Humidity Range

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

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