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Hydrogen Gas Sensing Characterizations Based on Nanocrystalline SnO<sub>2</sub> Thin Films Grown on SiO<sub>2</sub>/Si and Al<sub>2</sub>O<sub>3</sub> Substrates
摘要： High-quality nanocrystalline (NC) SnO2 thin films were grown on SiO2/Si and Al2O3 substrates using sol–gel spin coating method. The structural properties, surface morphologies and gas sensing properties of the NC SnO2 were investigated. XRD measurements showed a tetragonal rutile structure and the diffraction peaks for NC SnO2 thin films grown on Al2O3 substrates outperformed those of NC SnO2 films grown on SiO2/Si substrates. The surface morphology of the annealed SnO2 thin films at 500 oC appeared as polycrystalline with uniform nanoparticle distribution. Hydrogen (H2) gas sensing performance of the NC SnO2 was examined for H2 concentrations ranging from 150 ppm to 1000 ppm at different temperatures (room temperature, 75 and 125 oC) for over 50 min. The room temperature sensitivities for H2 gas sensors based on NC SnO2 thin films grown on Al2O3 and SiO2/Si substrates was 2570% and 600%, respectively upon exposure to 1000 ppm of H2 gas. While the sensitivity values at 125 oC increased to 9200% and 1950%, respectively.
关键词： Sensing,Room Temperature,Hydrogen,Nanocrystalline SnO2,Thin Films,Sol-Gel
更新于2025-09-23 15:22:29
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Investigation of local geometrical structure, electronic state and magnetic properties of PLD grown Ni doped SnO2 thin films
摘要： We have investigated the ferromagnetic behavior, electronic states and local geometrical structure of Ni (2 and 10 at %) doped SnO2 thin films. The films were successfully fabricated with the help of pulsed laser deposition (PLD) technique on Si (100) substrate under ultrahigh vacuum (UHV) condition. X-ray diffraction (XRD) results revealed the single phase character of SnO2 rutile lattice structure with P42/mnm space group. The inclusion of Ni ions into SnO2 matrix induced oxygen vacancy (Vo), enhanced the distortion in octahedral local symmetry and reduced the oxidation state of the host Sn4+ (SnO2) to Sn3+ (Sn2O3) these details have been estimated by Raman scattering, Near edge X-ray absorption fine structure (NEXAFS) spectra at Ni L3,2 and O K edges. Further quantitative details on the local geometrical structure around Ni ions were obtained via fitting the experimental Fourier transforms EXAFS spectra |X(R)| with FEFF6 code. The magnetization measurements performed at room temperature (RT) infers that the observed magnetic behavior of the films seems to be relevant to the same crystal growth condition (UHV) and might not be limited directly to the Ni dopant concentrations. The FM signal and the role of surface defects have been discussed based spin-split impurity band difference in the saturation moments even with increase the Ni content. Hence, the similarity in Ni doped SnO2 films displayed ferromagnetic (FM) signal, and there was no significant Ferromagnetism etc. percolation mechanism.
关键词： surface defects,XANES spectra,SnO2 nanostructured thin film,PLD,local symmetry,XRD,NEXAFS
更新于2025-09-23 15:22:29
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Correlation Between Currents, X-ray Diffraction Patterns and Transfer Characteristics of SnO <sub/>2</sub> Thin Film Transistor
摘要： SnO2 thin film transistor (TFT) was prepared with SiOC as a gate insulator on n-type Si and the correlation between bonding structures, the contact properties of SnO2 thin films and the transfer characteristics of TFTs was researched. The current of SnO2 thin films increased with increasing the crystallinity and the crystallinity of SnO2 was increased by annealing. The SnO2 deposited with much oxygen gas flows became an amorphous structure after annealing due to lowered crystallinity. On the other hand, the current decreased in the amorphous structure SnO2 with high oxygen vacancies. However, the ambipolar transfer characteristics of SnO2/SiOC TFT with an amorphous structure had higher stability-mobility than that of TFT with the crystallinity, because of the increment effect of the diffusion current at the depletion layer as the amorphous structure with high Schottky barrier (SB).
关键词： Amorphous Structure,SnO2,Capacitance,TFT,X-ray Diffraction
更新于2025-09-23 15:22:29
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Ultraviolet electroluminescence from nanostructural SnO2-based heterojunction with high-pressure synthesized Li-doped ZnO as a hole source
摘要： We report an ultraviolet (UV) electroluminescence (EL) in n-SnO2/p-ZnO heterojunction light-emitting diodes with the nanostructural SnO2 as an n-type layer and the Li-doped ZnO (ZnO:Li) synthesized by high-temperature high-pressure (HTHP) method as a high hole concentration p-type layer. Two kinds of SnO2 nanostructures including nanobelts (NBs) and nanowires (NWs) were used to fabricate n-type layers in the heterojunctions. The two heterojunctions with different SnO2 nanostructures demonstrate different light-emission feature in EL measurements. The SnO2 NBs/p-ZnO heterojunction shows a blue emission band centered at 416 nm under forward-bias voltage. A strong UV emission peak located at 391 nm was observed for the SnO2 NWs/p-ZnO heterojunction. Photoluminescence (PL) spectra indicate that the difference in EL is attributed to morphology-dependent light-emission feature in nanostructural SnO2 layer. Our results suggest that the nanostructural SnO2/ZnO:Li heterojunction is a potential and promising system in the UV optoelectronic field.
关键词： High-temperature high-pressure method,Light-emitting diode,Nanobelt,Nanowire,SnO2,Li-doped ZnO
更新于2025-09-23 15:22:29
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Electrochemical properties of chemically synthesized SnO2-RuO2 mixed films
摘要： The SnO2–RuO2 mixed films are prepared by successive ionic layer adsorption and reaction (SILAR) method. The SnO2 films combined with RuO2 are prepared by varying the deposition cycles of SILAR. The effect of combining SnO2 with RuO2 on structural, morphological and electrochemical properties is studied. It is observed that the crystalline nature of SnO2 changed to amorphous with increase in RuO2 deposition cycles. The morphology is also changed from fibrous-porous to compact after increasing RuO2 deposition cycles. The specific capacitance of SnO2 is increased from 4 to 185 F/g after combined with RuO2. The maximum utilization of RuO2 is observed with specific capacitance of 1010 F/g.
关键词： RuO2,SnO2,Supercapacitor,Thin films,Chemical synthesis,Charge–discharge
更新于2025-09-23 15:21:21
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Transparent Conductive Materials (Materials, Synthesis, Characterization, Applications) || Metallic Oxides (ITO, ZnO, SnO <sub/>2</sub> , TiO <sub/>2</sub> )
摘要： The material class of transparent conductive oxides (TCOs) combines two seemingly contradictory physical properties: high optical transmittance in the visible and near-infrared (NIR) spectral range (like insulators) and high electrical conductivity (like metals). These two key properties make TCO materials very well suited for transparent thin film electrodes for thin film solar cells, flat panel displays, light-emitting devices, or heated windows.
关键词： ZnO,light-emitting devices,SnO2,Transparent Conductive Oxides,thin film electrodes,ITO,solar cells,TiO2,flat panel displays,TCOs
更新于2025-09-23 15:21:21
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Structural Properties of (Sn1?xMgxO) Thin Films and Optical Parameter Dependence with Gamma Ray Irradiation
摘要： Tin-Magnesium oxide (Sn1?xMgxO) thin films were prepared on glass substrates using the chemical spray pyrolysis technique, whereupon the samples were irradiated by gamma rays using a Co-60 radioactive source. X-ray diffraction showed that all prepared films were polycrystalline in nature with a tetragonal structure and a preferential growth of crystallites in the (110) plane. In general, the average crystallite size, lattice constants, dislocation density and crystallite density decreased with increasing Mg doping from 0% to 8%. Further, atomic force microscopy showed that the thin films were smooth and homogenous. The optical properties were obtained by ultraviolet–visible spectrophotometry, and the transmittance and absorbance spectra before and after gamma ray irradiation were compared for all samples, whereby the absorption and extinction coefficients and real and imaginary parts of the dielectric were studied before and after irradiation. It was found that the energy band gap values decreased from 3.94 eV to 3.72 eV with increasing Mg doping from 0% to 8% before irradiation, and from 3.92 eV to 3.59 eV after irradiation. All optical constants increased with doping percentage before and after irradiation. Energy-dispersive x-ray spectroscopy showed that all structures contained Sn and O elements in the undoped state, and contained SnO2 and Mg in the doped state.
关键词： doping,SnO2 thin films,gamma ray,energy-dispersive x-ray technology,chemical spray pyrolysis,structural properties
更新于2025-09-23 15:21:21
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Orthogonal gas sensor arrays by chemoresistive material design
摘要： Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2–5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R2 of 0.68.
关键词： Ethanol,WO3,SnO2,Electronic nose,Ammonia,Gas sensor,Acetone,Flame spray pyrolysis,MoO3
更新于2025-09-23 15:21:21
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Effect of pH Values on the Structural, Optical and Electrical Properties of SnO2 Nanostructures
摘要： In the present work, we have synthesized the SnO2 nanostructures via precipitation method under optimal conditions at different pH values (3, 7 and 11) and studied the effect of different pH values on the structural, optical and electrical properties. The prepared samples are characterized by XRD, FESEM, TEM, PL, UV–Visible, FTIR spectroscopy and EIS measurements. XRD analysis reveals the tetragonal crystal structure for the prepared SnO2 nanostructures. TEM images show that the morphology of SnO2 nanostructures changed from spherical to hexagonal as pH values increased from 3 to 11. The deconvoluted PL spectra show various defects present in the synthesized samples that act as luminescent centers. The absorption spectra revealed that the maximum optical band-gap is obtained for SnO2 nanostructures synthesized using acidic solutions. The FTIR spectrum verifies the presence of stretching vibration mode of O-Sn-O bond and, stretching and bending bonds of O-H bonds in the prepared samples. A detailed exploration on frequency and temperature dependent impedance properties of SnO2 nanostructures has been done with the change in pH values.
关键词： Impedance spectroscopy,SnO2,PL,TEM,pH values,Nanostructures,FESEM
更新于2025-09-23 15:21:21
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The Enhanced NO2 sensing properties of SnO2 nanoparticles/reduced graphene oxide composite
摘要： Multiple techniques were utilized to characterize the structure and morphology of the SnO2/reduced graphene oxide (rGO) composite, in which the composite was prepared by a facile one-pot microwave-assisted hydrothermal method. As a result, SnO2 nanoparticles with diameters of 3-5 nm were anchored uniformly on both sides of the rGO sheets. Meanwhile, a series of resistive-type gas sensors based on SnO2/rGO composite and pure SnO2 were fabricated and tested for analyzing the effects on introducing rGO. The results revealed that, the composite exhibited obviously enhanced gas sensing properties towards NO2 with high response, fast response and recovery speed, and good selectivity and reproducibility. At 75°C, the response of the composite to 350 ppb NO2 was about 6.6 times of that to pure SnO2. In addition, the response and recovery time of the sensor was greatly reduced from 39.2/54.7 to 6.5/1 minutes, and the detecting limit of the sensor was even as low as 50 ppb. Provided with the enlarged surface area and local p-n heterojunctions, the synergistic effect of SnO2 nanoparticles and rGO contributed to the enhanced gas sensing properties of SnO2/rGO composite.
关键词： SnO2,Graphene,Heterojunctions,Microwave-assisted hydrothermal,Gas sensor
更新于2025-09-23 15:21:21