Aerosol-Assisted CVD of SnO2 Thin Films for the Room-Temperature Detection of Hydrogen Sulfide

2013 ◽  
Vol 543 ◽  
pp. 422-425
Author(s):  
Huan Liu ◽  
Min Li ◽  
Jiu Xiao Wan ◽  
Jun Zhao ◽  
Qiu Yun Fu ◽  
...  
Keyword(s):  
Thin Films ◽  
Gas Flow ◽  
Room Temperature ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Temperature Detection ◽  
Low Concentrations ◽  
Initial Resistance ◽  
Deposition Conditions

High-quality SnO2 thin-film materials capable of detecting H2S gas of low concentrations at room temperature was demonstrated in this paper. We employed aerosol-assisted chemical vapor deposition process for the deposition of SnO2 thin films on alumina substrates with pre-patterned electrodes. The gas-sensing performances of the films prepared under different deposition conditions were systematically compared and analyzed. When SnCl2·2H2O was used as the precursor, a response sensitivity of 98.4 toward 50 ppm of H2S at room temperature was achieved. At room temperatures, the resistance upon the H2S gas exposure could recover to 90% of the initial resistance of the sensor when the H2S gas flow was turned off.

scholarly journals Effect of GNWs/NiO-WO3/GNWs Heterostructure for NO2 Gas Sensing at Room Temperature

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 626
Author(s):  
Seokhun Kwon ◽  
Seokwon Lee ◽  
Joouk Kim ◽  
Chulmin Park ◽  
Hosung Jung ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Room Temperature ◽  
Microwave Plasma ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Concentration ◽  
Negative Change ◽  
Low Concentrations ◽  
Detection Characteristics ◽  
No2 Detection

Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5–7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.

Nanostructural and Optical Features of nc-Si:H Thin Films Prepared by Plasma Enhanced Chemical Vapor Deposition Techniques

2006 ◽  
Vol 510-511 ◽  
pp. 962-965
Author(s):  
Jae Hyun Shim ◽  
Nam Hee Cho ◽  
Y.J. Kim ◽  
Chin Myung Whang ◽  
Won Seung Cho ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Flow Rate ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Amorphous Matrix ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Silicon Nanocrystallites ◽  
Deposition Conditions

The nanostructural and optical features of hydrogenated nanocrystalline silicon (nc-Si:H) thin films, which were prepared by plasma enhanced chemical vapor deposition (PECVD), were investigated as a function of deposition conditions. It was found that the crystallite size varied with the relative fraction of Si-H3 bonds in the films, [ ] eger n n n H Si H Si int 3 1 3 / ] [ = = ∑ − − , which was sensitively related with the flow rate of SiH4 reaction gas. The silicon nanocrystallites in the films enlarged from ~2.0 to ~8.0 nm in their size with increasing gas flow rate, while the PL emission energy varied from 2.5 to 1.8 eV; the relative fractions of the Si-H3, Si-H2, and Si-H bonds in the amorphous matrix were also varied sensitively with the SiH4 flow rate. A model for the nanostructure of the nc-Si:H films was suggested to discribe the variations in the size and chemical bonds of the nanocrystallites as well as the amorphous matrix depending on the deposition conditions.

scholarly journals Highly sensitive and room temperature detection of ultra-low concentrations of O3 using self-powered sensing elements of Cu2O nanocubes

2019 ◽  
Vol 1 (5) ◽  
pp. 2009-2017 ◽  
Author(s):  
E. Petromichelaki ◽  
E. Gagaoudakis ◽  
K. Moschovis ◽  
L. Tsetseris ◽  
T. D. Anthopoulos ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Room Temperature ◽  
Gas Sensing ◽  
Low Cost ◽  
New Class ◽  
Temperature Detection ◽  
Low Concentrations ◽  
Highly Sensitive ◽  
Self Powered ◽  
P Type

The fundamental development of the design of novel self-powered ozone sensing elements, operating at room temperature, based on p-type metal oxides paves the way to a new class of low cost, highly promising gas sensing devices.

MOCVD OF SnO2 on Silicon Microhotplate Arrays for use un Gas Sensing Applications

1995 ◽  
Vol 415 ◽  
Author(s):  
F. Dimeo ◽  
S. Semancik ◽  
R.E. Cavicchi ◽  
J.S. Suehle ◽  
P. Chaparala ◽  
...  
Keyword(s):  
Thin Films ◽  
Gas Sensing ◽  
Low Cost ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Medical Diagnostics ◽  
Electrical Contacts ◽  
Quantitative Detection ◽  
Sensing Applications ◽  
Resistive Heater

ABSTRACTThe quantitative detection of gas concentrations in mixed atmospheres is becoming increasingly important in manufacturing processing, environmental monitoring, and medical diagnostics. Several conductive oxides, such as SnO2, ZnO, and TiO2, are well known to exhibit changes in resistivity when exposed to various gases at temperatures ranging from 200–500°C. Current discrete devices based on resistive changes such as the Taguchi sensor, however, suffer from certain performance problems, including poor gas detection specificity. Integrated arrays of sensors, fabricated using planar technology, offer a promising solution to these problems, as well as other benefits such as low power consumption and low cost.In this paper, we report the results of using Metalorganic Chemical Vapor Deposition (MOCVD) to fabricate thin films of SnO2 on microhotplate arrays. The studied arrays contain 4 micromachined, suspended elements, each having an integrated resistive heater that produces a rapid thermal rise time ∼3 msec. By separately heating individual elements, we can take advantage of the thermally selective nature of the MOCVD process to limit deposition to these areas, resulting in a maskless deposition process. In addition, these array elements have surface electrical contacts that permit the measurement of the resistance of the thin films during deposition, as well as when they are operated in a gas sensing mode. In situ growth measurements will be reported.

Ferroelectric and Piezoelectric Properties of MOCVD Pb(Mg1/3Nb2/3)O3-PbTiO3 Epitaxial Thin Films

1999 ◽  
Vol 596 ◽  
Author(s):  
P. K. Baumann ◽  
G. R. Bai ◽  
S. K. Streiffer ◽  
O. Auciello ◽  
K. Ghosh ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Chemical Vapor ◽  
Epitaxial Thin Films ◽  
Zero Bias ◽  
Pt Films ◽  
Ti Content ◽  
Ferroelectric And Piezoelectric Properties ◽  
Deposition Conditions

AbstractWe have grown epitaxial Pb(Mg1/3Nb2/3)O3 (PMN) and (1-x)(Pb(Mg1/3Nb2/3)O3)- x(PbTiO3) (PMN-PT) thin films by metalorganic chemical vapor deposition at 700 - 780°C on (100) SrTiO3 and SrRuO3/SrTiO3 substrates. The zero-bias permittivity and loss measured at room temperature and 10 kHz for 220 nm thick pure PMN films were 900 and 1.5%, respectively. For PMN-PT films, the small-signal permittivity ranged from 1000 to 1500 depending on deposition conditions and Ti content; correspondingly low values for the zero-bias dielectric loss between 1 and 5% were determined for all specimens. For PMN-PT with x of approximately 0.30–0.35, polarization hysteresis with Pr,≈18μC/cm2 was obtained. Initial piezoresponse data are discussed.

Investigation of ultra-thin films of YBa2Cu3O7−δ grown on MgO

1990 ◽  
Vol 48 (4) ◽  
pp. 6-7
Author(s):  
S.K. Streiffer ◽  
C.B. Eom ◽  
J.C. Bravman ◽  
T.H. Geballet
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Deposition Process ◽  
Nucleation And Growth ◽  
Multilayer Structures ◽  
Rf Power ◽  
Oxygen Loss ◽  
Transmission Electron ◽  
Single Target ◽  
Mtorr Argon

The study of very thin (<15 nm) YBa2Cu3O7−δ (YBCO) films is necessary both for investigating the nucleation and growth of films of this material and for achieving a better understanding of multilayer structures incorporating such thin YBCO regions. We have used transmission electron microscopy to examine ultra-thin films grown on MgO substrates by single-target, off-axis magnetron sputtering; details of the deposition process have been reported elsewhere. Briefly, polished MgO substrates were attached to a block placed at 90° to the sputtering target and heated to 650 °C. The sputtering was performed in 10 mtorr oxygen and 40 mtorr argon with an rf power of 125 watts. After deposition, the chamber was vented to 500 torr oxygen and allowed to cool to room temperature. Because of YBCO’s susceptibility to environmental degradation and oxygen loss, the technique of Xi, et al. was followed and a protective overlayer of amorphous YBCO was deposited on the just-grown films.

Chemical Vapor Deposition of Sr1−xBaxNb2O6 Thin Films Using Metal Alkoxide Precursors

2000 ◽  
Vol 15 (8) ◽  
pp. 1702-1708
Author(s):  
Ruichao Zhang ◽  
Ren Xu
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Single Phase ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Thin Layers ◽  
Metal Alkoxide ◽  
Stoichiometry Control ◽  
Alkoxide Precursors

A novel two-step metalorganic chemical vapor deposition process was used in this study to prepare Sr1−xBaxNb2O6 (SBN) thin films. Two thin layers of single-phase SrNb2O6 and BaNb2O6 were deposited alternately on a silicon substrate, and the solid solution of SBN was obtained by high-temperature annealing. The stoichiometry control of the SrNb2O6 and the BaNb2O6 thin films was achieved through deposition process control, according to the evaporation characteristics of double metal alkoxide. The evaporation behavior of double metal alkoxide precursors SrNb2(1-OC4H9)12 and BaNb2(1-OC4H9)12 was studied, and the results were compared with the evaporation of single alkoxide Nb(1-OC4H9)5.

Effect of Nitrogen Doping on the Structure and Optical Properties of N-Type Hydrogenated Amorphous Silicon Thin Films

2011 ◽  
Vol 383-390 ◽  
pp. 6980-6985
Author(s):  
Mao Yang Wu ◽  
Wei Li ◽  
Jun Wei Fu ◽  
Yi Jiao Qiu ◽  
Ya Dong Jiang
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Silicon Thin Films ◽  
Frequency Plasma ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon (a-Si:H) thin films doped with both Phosphor and Nitrogen are deposited by ratio frequency plasma enhanced chemical vapor deposition (PECVD). The effect of gas flow rate of ammonia (FrNH3) on the composition, microstructure and optical properties of the films has been investigated by X-ray photoelectron spectroscopy, Raman spectroscopy and ellipsometric spectra, respectively. The results show that with the increase of FrNH3, Si-N bonds appear while the short-range order deteriorate in the films. Besides, the optical properties of N-doped n-type a-Si:H thin films can be easily controlled in a PECVD system.

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