Highly sensitive SnO2 thin film NO2 gas sensor operating at low temperature
TL;DR: In this article, the structural and morphological properties of thin nano-crystalline SnO 2 and WO 3 -doped SnO2 films are investigated using XRD, TEM and AFM.
Abstract: Thin films of pure nano-crystalline SnO 2 and WO 3 -doped SnO 2 in different concentrations (3 wt.% and 5 wt.%) are deposited using sol–gel spin coating technique on glass substrates. The structural and morphological properties of these films are investigated using XRD, TEM and AFM. The sensitivity and selectivity of these films are tested to different reducing and oxidizing gases such as SO 2 , NH 3 , NO 2 and ethanol. A SnO 2 thin film with 5 wt.% WO 3 shows very high responses to NO 2 (four orders of magnitude in the value of ( R g − R a )/ R a ; R g and R a are the resistance in NO 2 and in air, respectively) and excellent selectivity for NO 2 gas at a low operating temperature of 150 °C. The effect of WO 3 on the sensing characteristics of these films towards NO 2 is discussed.
Citations
More filters
TL;DR: A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented.
Abstract: A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented.
368 citations
Cites background from "Highly sensitive SnO2 thin film NO2..."
...Investigators have also studied other SMO films such as SnO2 [103,115-126], ZnO [127-134], Te-oxide [135,136], Mo [137], gold [107], Pt [108], copper [138], and indium oxides [111,112]....
[...]
TL;DR: In this paper, a novel and selective gas-sensing platform with reduced graphene oxide (RGO) decorated with tin oxide (SnO2) nanocrystals (NCs) was presented.
Abstract: We report a novel and selective gas-sensing platform with reduced graphene oxide (RGO) decorated with tin oxide (SnO2) nanocrystals (NCs). This hybrid SnO2 NC–RGO platform showed enhanced NO2 but weakened NH3 sensing compared with bare RGO, showing promise in tuning the sensitivity and selectivity of RGO-based gas sensors.
275 citations
Abstract: A SnO 2 /MWCNTs composite-based NH 3 sensor working at room temperature was fabricated by thin film microelectronic technique. The gas-sensitive composite thin film was prepared by using both commercially available multi-walled carbon nanotubes (MWCNTs) and nanosized SnO 2 dispersion. Microstructure and surface morphology of the composite were investigated and they revealed that the MWCNTs were still present and well embedded by SnO 2 particles in the composite powder as well as in the composite thin film at calcination temperatures up to 550 °C. The effect of the preparation process of the sensitive composite thin film on gas-sensing properties was examined, and the preparation process parameters such as MWCNTs content, MWCNTs diameter, calcination temperature, and film thickness were optimized. At room temperature, the optimal composite sensor exhibited much higher response and faster response-recovery (less than 5 min) to NH 3 gas of concentrations ranging from 60 to 800 ppm, in comparison with the carbon nanotubes-based NH 3 sensor. Based on the experimental observations, a model of potential barrier to electronic conduction at the grain boundary for the CNTs/SnO 2 composite sensors was also discussed.
203 citations
Cites methods or result from "Highly sensitive SnO2 thin film NO2..."
...Comparing with the CNTs-based NH3 sensor [27,29] and the SnO2-based NH3 sensor [29–31] reported previously, as-synthesized composites SnO2/MWCNTs-based sensors have a higher response to NH3 gas at room temperature....
[...]
...It has been reported in literatures [25–31] that SnO2/CNTs composite sensors have better performance compared to the SnO2 and CNTs-based NH3 gas sensors....
[...]
...The NH3 gas sensors based on CNTs [25,26] and SnO2 [27–31] have been extensively investigated....
[...]
TL;DR: In this article, the authors examined the possibility of using SnO 2 hollow spheres mediated by carbon microspheres for the efficient detection of NO 2 gas, and found that the sensors were more sensitive to NO 2 than to ethanol, methanol, gasoline, acetone, CCl 4 and NH 3 when operated at 160°C.
Abstract: This work examined the possibility of using SnO 2 hollow spheres mediated by carbon microspheres for the efficient detection of NO 2 gas. The influences of gas concentration, operating temperature, crystallite (grain) size and structure feature on the sensing performance of the sensors based on SnO 2 hollow spheres were comprehensively studied. The SnO 2 hollow spheres had a mean crystallite size of 12.7, 14.1 and 22.8 nm when calcined at 450, 500 and 550 °C, respectively. It was found that the SnO 2 hollow spheres calcined at 450 °C with a crystallite size of 12.7 nm were the most sensitive to NO 2 gas. The sensor also had a better selectivity to NO 2 than to ethanol, methanol, gasoline, acetone, CCl 4 and NH 3 when operated at 160 °C.
166 citations
TL;DR: In this paper, the effect of growth pressure on the surface morphology and structural property of SnO2 film was studied using Atomic force microscopy (AFM), Scanning electron microscopy and X-ray Diffraction (XRD) respectively.
Abstract: Semiconducting SnO2 thin films having higher value of electrical conductivity have been deposited using RF sputtering technique in the reactive gas environment (30% O2 + 70% Ar) using a metallic tin (Sn) target for detection of oxidizing NO2 gas. The effect of growth pressure (12–18 mTorr) on the surface morphology and structural property of SnO2 film was studied using Atomic force microscopy (AFM), Scanning electron microscopy (SEM) and X-ray Diffraction (XRD) respectively. Film deposited at 16 mTorr sputtering pressure was porous with rough microstructure and exhibits high sensor response (∼2.9 × 104) towards 50 ppm NO2 gas at a comparatively low operating temperature (∼100 °C). The sensor response was found to increase linearly from 1.31 × 102 to 2.9 × 104 while the response time decrease from 12.4 to 1.6 min with increase in the concentration of NO2 gas from 1 to 50 ppm. The reaction kinetics of target NO2 gas on the surface of SnO2 thin film at the Sn sites play important role in enhancing the response characteristics at lower operating temperature (∼100 °C). The results obtained in the present study are encouraging for realization of SnO2 thin film based sensor for efficient detection of NO2 gas with low power consumption.
143 citations
References
More filters
Book•
01 Jan 1956
TL;DR: In this article, the authors present a chemical analysis of X-ray diffraction by Xray Spectrometry and phase-diagram Determination of single crystal structures and phase diagrams.
Abstract: 1. Properties of X-rays. 2. Geometry of Crystals. 3. Diffraction I: Directions of Diffracted Beams. 4. Diffraction II: Intensities of Diffracted Beams. 5. Diffraction III: Non-Ideal Samples. 6. Laure Photographs. 7. Powder Photographs. 8. Diffractometer and Spectrometer. 9. Orientation and Quality of Single Crystals. 10. Structure of Polycrystalline Aggregates. 11. Determination of Crystal Structure. 12. Precise Parameter Measurements. 13. Phase-Diagram Determination. 14. Order-Disorder Transformation. 15. Chemical Analysis of X-ray Diffraction. 16. Chemical Analysis by X-ray Spectrometry. 17. Measurements of Residual Stress. 18. Polymers. 19. Small Angle Scatters. 20. Transmission Electron Microscope.
17,428 citations
TL;DR: In this paper, the authors demonstrated that the sensing characteristics of a semiconductor gas sensor using SnO2 can be improved by controlling fundamental factors which affect its receptor and transducer functions.
Abstract: It is demonstrated that the sensing characteristics of a semiconductor gas sensor using SnO2 can be improved by controlling fundamental factors which affect its receptor and transducer functions. The transducer function is deeply related with the microstructure of the elements, i.e., the grain size of SnO2 (D) and the depth of the surface space-charge layer (L). The sensitivity is drastically promoted when D is made comparable to or less than 2L, either by control of D for pure SnO2 elements or by control of the Debye length for impurity-doped elements. On the other hand, the receptor function is drastically modified by the introduction of foreign receptors on the surface of SnO2. In the particular cases of Pd and Ag promoters, the oxides (PdO and Ag2O) formed in air interact with the SnO2 surface to produce an electron-deficient space-charge layer, and this contributes much to promoting the gas sensitivity. For a test gas having a specific reactivity, such specificity can be utilized for exploiting gas-selective receptors, as exemplified by CuOSnO2 and La2O3SnO2 elements, which detect H2S and ethanol gas respectively very sensitively.
1,534 citations
TL;DR: In this paper, the effects of grain size on gas sensitivity were investigated by using porous sintered SnO2 elements fabricated with pure and impurity-doped SnO 2 elements.
Abstract: Effects of grain size on gas sensitivity (S) are investigated by using porous sintered SnO2 elements fabricated with pure SnO2, foreign oxide-stabilized SnO2, or impurity-doped SnO2. When the SnO2 crystallite size (D) is controlled to a size in the range 5–32 nm, S for H2, CO and i-C4H10 is found to increase steeply as D decreases to be comparable with or less than 2L (≈ 6 nm) is both pure and stabilized elements, where L is the depth of the space-charge layer. However, S for ethyl alcohol gas is found to be also affected by surface acid-base properties, being greatly promoted by basic oxides. It is found that the control of L by doping impurities (Al3+ or Sb5+) into the SnO2 lattice results in great changes in S even when D is the same. Thus Al-doped SnO2 shows high sensitivity with increasing L even at D above 20 nm, while Sb-doped SnO2 is insensitive in the whole D region. A model for the grain-size effects is proposed, in which the transducer function is operated by a mechanism of grain control, neck control or grain-boundary control, depending on D.
1,275 citations
Book•
01 Jan 1989
TL;DR: Silicon Based Chemical Sensors as mentioned in this paper : Gas Sensors based on Semiconductor Powders are used for solid state chemical sensor applications, and they have been shown to be useful in many applications.
Abstract: Introduction. Solid State Background. Solid/Gas Interfaces. Solid/Liquid Interfaces. Catalysis Background. Membrane Background. Biosensor Principles. Principles of Chemfet Operation. Silicon Based Chemical Sensors. Thin Film Gas Sensors. SolidElectrolytes-Devices. Gas Sensors Based on Semiconductor Powders. Application of Solid State Chemical Sensors.
953 citations