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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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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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Investigating the impact of thermal annealing on the photovoltaic performance of chemical bath deposited SnO2/p-Si heterojunction solar cells
摘要： The current work investigates the impact of annealing temperature on the optoelectronic properties of SnO2 thin films grown by chemical bath deposition (CBD) method. The as-grown SnO2 films, on p-Si substrate, are annealed at 200 °C and 400 °C for 10 min in Ar ambient for investigating the impact of such annealing on the performance of SnO2/p-Si heterojunction solar cells. The growth of a uniform SnO2 film on Si surface has been confirmed from SEM studies and the chemical composition and optical properties of the as-grown and annealed films are investigated in detail by employing XRD and ellipsometric measurements. Absorption coefficient of the samples is observed to vary in the range of 24 × 105 – 60 × 105/m, at its band gap (3.0 eV). The current–voltage characteristics under both dark and illuminated conditions suggest superior voltaic performance of the 200 °C annealed SnO2 film. The short-circuit current density, open-circuit voltage and fill-factor are obtained to be 0.45 mA/cm2, 5.41 mA/cm2 and 0.4 V, 0.34 V and 13%, 8% respectively for as-grown and 200 °C annealed samples. The maximum power conservation efficiency (η) of 4.9% is obtained for the 200 °C annealed sample. Thus, the study indicates the potential of CBD-grown SnO2 film for photovoltaic applications.
关键词： Optoelectronic properties,Heterojunction solar cells,Chemical bath deposition,Annealing temperature,SnO2 thin films
更新于2025-09-12 10:27:22
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Effect of the Substrate Temperature on the Properties of SnO<sub>2</sub> Thin Films Prepared by Ultrasonic Spray for Solar Cells Applications
摘要： Structural, optical properties of SnO2 thin films deposited by spray ultrasonic technique were investigated by varying substrate temperature. The structural characterization of the films was analyzed via X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). These studies indicated that the layers were polycrystalline. Films surface morphologies were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical absorption spectrum was recorded using the UV-VIS-NIR spectroscopy and the films were found to be transparent. The optical transmittance varied with substrate temperature from 60–80% over a wide range of wavelength. Optical measurements showed that the layers had a relatively high absorption coefficient of 105 cm?1. A shift in the absorption edge was observed and the films exhibited direct transitions with band gap energies ranging from 3.85 to 3.94 eV.
关键词： transparent and conductive tin dioxide,SnO2 thin films,spray ultrasonic technique,substrate temperature
更新于2025-09-11 14:15:04