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1.
Ga-doped SnO2 thin films deposited by spray pyrolysis were investigated as oxygen gas sensors. Gallium was added to the films to enhance the catalytic activity of the surface’s film to oxygen. Film resistance was studied in an environment of dry air loaded with oxygen in excess at partial pressures in the range from 0 to 8.78×103 Pa. The best sensitivity lies close to partial pressures of 133.3 Pa. Film sensitivity reach a maximum at 350 °C. For this temperature and a doping concentration of 3 at.% of Ga in the starting solution, a sensitivity up to 2.1 was obtained. 相似文献
2.
《Thin solid films》2010,519(2):568-572
The paper presents a comparative approach concerning the properties of SnO2 thin layers obtained via spray pyrolysis deposition (SPD) using precursors with different molar concentrations. The photocatalytic efficiency of the samples was tested in the photodegradation of methylene blue. The sample obtained from 0.001 M precursor exhibit higher electrical conductivity (current-voltage curves) and photocatalytic properties compared with the samples obtained from precursors with lower molar concentrations. Regardless of the molar concentrations the samples present tetragonal structure (X-ray diffraction) and granular morphology (atomic force microscopy). 相似文献
3.
TiO2-coated SnO2 nanosheet (TiO2-SnO2 NS) films about 300 nm in thickness were fabricated on fluorine-doped tin oxide glass by a two-step process with facile solution-grown approach and subsequent hydrolysis of TiCl4 aqueous solution. The as-prepared TiO2-SnO2 NSs were characterized by scanning electron microscopy and X-ray diffraction. The performances of the dye-sensitized solar cells (DSCs) with TiO2-SnO2 NSs were analyzed by current-voltage measurements and electrochemical impedance spectroscopy. Experimental results show that the introduction of TiO2-SnO2 NSs can provide an efficient electron transition channel along the SnO2 nanosheets, increase the short current density, and finally improve the conversion efficiency for the DSCs from 4.52 to 5.71%. 相似文献
4.
Structural, electrical and optical characteristics of SnO2:Sb thin films by ultrasonic spray pyrolysis 总被引:1,自引:0,他引:1
Antimony-doped tin oxide (SnO2:Sb) thin films were fabricated by an ultrasonic spray pyrolysis method. The effect of antimony doping on the structural, electrical and optical properties of tin oxide thin films were investigated. Tin(II) chloride dehydrate (SnCl2·2H2O) and antimony(III) chloride (SbCl3) were used as a host and a dopant precursor. X-ray diffraction analysis showed that the non-doped SnO2 thin film had a preferred (211) orientation, but as the Sb-doping concentration increased, a preferred (200) orientation was observed. Scanning electron microscopy studies indicated that the polyhedron-like grains observed for the non-doped SnO2 thin films became rounder and decreased in size with the Sb-doping concentration. The lowest resistivity (about 8.4 × 10− 4 Ω·cm) was obtained for the 3 at.% Sb-doped films. Antimony-doping led to an increase in the carrier concentration and a decrease in Hall mobility. The transmittance level in the near infrared region was lowered with the Sb-doping concentration. 相似文献
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6.
SnO2 nanograss array films (SNAFs) were synthesized on indium tin oxide glass substrates by hydrothermal method. The effects of preparing conditions such as precursor concentration, reaction temperature and growth time on the formation of the SNAFs have been investigated in detail by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and photoluminescence spectrum. It is shown that the precursor concentration plays an important role in determining the morphology of the prepared SnO2. The average diameter, length and growth rate of the SNAFs can be controlled to some extent by varying growth time. The reaction temperature has also influence on the growth rate of SNAFs. Moreover, the growth mechanism of the SNAFs was also discussed. Room-temperature photoluminescence spectra were further carried out to investigate their optical properties. 相似文献
7.
In this paper we present the results of Atomic Force Microscopy (AFM) characterisation of the surface morphology of the L-CVD SnO2 thin films prepared by L-CVD technology and studied after exposure to air, dry air oxidation, and ion beam profiling. The L-CVD SnO2 thin films after air exposure have a very smooth surface morphology with an average surface roughness (RMS) smaller than 0.5 nm, and average and maximal grain heights of about 1 and 2 nm, respectively. After dry air oxidation the L-CVD SnO2 thin films exhibit an average surface roughness (RMS), as well as the average and maximal grain height, increased by one order of magnitude. Finally, after the ion beam profiling the L-CVD SnO2 thin films exhibit an evidently disordered structure with a lot of craters. These experiments showed that the L-CVD SnO2 thin films exhibit a very high quality surface morphology, what can be useful for solar cells and gas sensors application. 相似文献
8.
Pure SnO2 films and Ag-, Cu-, Pt-, and Pd-doped SnO2 films were investigated for H2S sensing properties. SnO2 films were deposited by DC magnetron sputtering at various substrate temperatures and discharge gas pressures. As the discharge gas pressure increased and the substrate temperature decreased, the film became porous. Doping with Cu or Ag film improved the sensitivity, and the highest sensitivity was obtained in the porous SnO2 film coated with an Ag film 16 nm thick. According to the X-ray diffraction (XRD) pattern, Ag deposited on SnO2 film transformed to Ag2S upon exposure to H2S. When the Ag-doped film sensor was operated at a low temperature, the sensitivity was extremely high, but the recovery was insufficient. By increasing the operation temperature, the recovery was improved but the sensitivity decreased. 相似文献
9.
The aim of the present work is to test the sensing behaviour of tin dioxide nanowires, which have been grown directly onto a sensing device. This device consists in an alumina substrate provided with platinum interdigitated microelectrodes and a Pt heater on the reverse side. The nanowire growing process based on a vapour-liquid-solid method consists of three steps: deposition of a tin thin film by DC sputtering, a 5 nm-thick Au layer deposition and an annealing treatment in the presence of oxygen for the growth of the SnO2 nanowires.These samples have been tested under different concentrations of formaldehyde (HCHO), showing a high sensitivity and very short response and recovery times even at low operating temperatures (130 °C). 相似文献
10.
In this paper we present the results of XPS study of the surface chemistry of L-CVD SnO2 thin films onto Si(100) before and after subsequent additional oxidation. Moreover, the ageing effect was also studied in order to check the influence of ambient oxidation. As-deposited L-CVD SnO2 thin films exhibit evident nonstoichiometry with the relative concentration [O]/[Sn] equal to 1.29 ± 0.1. After in situ oxidation at high temperature (800 K) the relative concentration [O]/[Sn] increases to 1.95 ± 0.05 which corresponds to the almost stoichiometric SnO2. Almost the same relative concentration [O]/[Sn] of L-CVD SnO2 thin films has been obtained after long term exposure to air. The oxidation states of L-CVD SnO2 thin films in both cases were confirmed by the shape analysis of corresponding XPS O1s and Sn3d5/2 peaks using the decomposition procedure. For the as-deposited L-CVD SnO2 thin films a mixture of SnO and SnO2 was observed, while for the oxidized L-CVD SnO2 thin films the domination of SnO2 was determined. 相似文献
11.
Jaswinder Kaur 《Thin solid films》2010,518(14):3982-260
The role of surface morphology of MoO3-doped SnO2 thin film on the gas sensing properties is analyzed. SnO2 thin films doped with 1, 3, 5 and 10 wt% MoO3 are prepared by sol-gel spin coating process. Structural and morphological properties are studied using glancing angle X-ray diffractometer, atomic force microscopy, transmission electron microscopy and high resolution transmission electron microscopy. Energy dispersive X-ray analysis and X-ray photoelectron spectroscopy studies are used for chemical analysis. A good correlation is found between the characteristics of the surface and gas sensing properties of these films. MoO3 addition is found responsible for increase in acidic nature of films which in turn increases their sensitivity and selectivity towards NO2 gas. 相似文献
12.
Fluidized chemical vapor deposition (FCVD) technology was developed for coating SnO2 thin film on Al2O3 ultrafine particles. TEM and HREM analysis found that SnO2 films with different structures were deposited by controlling the coating temperature, reactant concentration, etc. Nanocrystalline SnO2 film was coated at 573.15 K by gas phase reaction of SnCl4 with H2O. EPMA and EDS studies indicated that the distribution of SnO2 inner and outer of the agglomerates was uniform. Nucleation and film deposition were coexisted mechanism during the FCVD coating process. The fraction of SnO2 in the composite particles increased with increasing coating temperature, SnCl4 concentration, and coating time. The mass fraction of SnO2 in the composite particles increased strongly with the ratio of PH2O and PSnCl4 at low mole ratio of H2O with SnCl4, but increased little under the conditions of excess H2O with respect to SnCl4. 相似文献
13.
Toshinari Yamazaki Hitosi Okumura Cheng-Ji Jin Atsushi Nakayama Toshio Kikuta Noriyuki Nakatani 《Vacuum》2005,77(3):237-243
Undoped and Pd-doped SnO2 films were deposited under various conditions for the investigation of the effect of Pd doping, porosity, and thickness on their H2 gas sensing properties. The temperature of the substrate and the pressure of the discharge gas were varied. All films formed were composed of columns with thicknesses between 20 and 30 nm. The film density decreased as the discharge gas pressure increased and the substrate temperature decreased. It showed values between 4.2×103 and 7.0×103 kg/m3 depending on the deposition condition. Low film density and Pd doping resulted in high sensitivity and fast response. The largest sensitivity was observed for a Pd-doped film with a low density of 4.7×103 kg/m3 and a thickness of 20 nm. 相似文献
14.
W. Hamd 《Thin solid films》2009,518(1):1-5786
Tin oxide (SnO2) films have been grown onto (006) sapphire substrates by sol-gel dip-coating using tin alkoxide solutions. It is shown, using grazing-incidence X-ray diffraction, reciprocal space mapping and atomic force microscopy, that thermal annealing at 500 °C induces the crystallization of SnO2 in the rutile-type phase. Further annealing treatments at temperatures lower than 1100 °C give rise to slow grain growth controlled by surface diffusion, whereas rapid grain growth (controlled by an evaporation-condensation mechanism) takes place at temperatures higher than 1100 °C. Concomitantly, the film splits into isolated islands and a fibre texture occurs at higher temperatures. 相似文献
15.
J. Jeong S. P. Choi K. J. Hong Y. T. O H. J. Song J. B. Koo I. H. Lee J. S. Park D. C. Shin 《Materials Science and Engineering: B》2004,110(3):240-242
Abnormal grain growth (AGG) occurs when SnO2 thin films are deposited by conventional thermal CVD at 475 °C, and high-resolution transmission electron microscopy shows some of the interfaces to be atomically faceted. However, when deposited at 525 °C normal grain growth (NGG) occurs with all the interfaces smoothly curved and atomically rough. This correlation between interface structure and grain growth behavior is consistent with that observed previously in bulk materials. For the application of SnO2 thin films in sensors and transparent electrodes, 525 °C, which is just above the faceting transition temperature, was found to be the optimum deposition temperature due to its small grain size and high surface to volume ratio. 相似文献
16.
Yanbai Shen Toshinari Yamazaki Zhifu Liu Dan Meng Toshio Kikuta 《Thin solid films》2009,517(21):6119-2463
Pd-doped SnO2 sputtered films with columnar nanostructures were deposited using reactive magnetron sputtering at the substrate temperature of 300 °C and the discharge gas pressures of 1.5, 12, and 24 Pa. Structural characterization by means of X-ray diffraction and scanning electron microscopy shows that the films composed of columnar nanograins have a tetragonal SnO2 structure. The films become porous as the discharge gas pressure increases. Gas sensing measurements demonstrate that the films show reversible response to H2 gas. The sensitivity increases as the discharge gas pressure increases, and the operating temperature at which the sensitivity shows a maximum is lowered. The highest sensitivity defined by (Ra − Rg) / Rg, where Ra and Rg are the resistances before and after exposure to H2, 84.3 is obtained for the Pd-doped film deposited at 24 Pa and 300 °C upon exposure to 1000 ppm H2 gas at the operating temperature of 200 °C. The improved gas sensing properties were attributed to the porosity of columnar nanostructures and catalytic activities of Pd doping. 相似文献
17.
Valérie Stambouli Maël Manesse Frédéric Férrieu Laetitia RapenneHervé Roussel Patrick ChaudouëtSabine Szunerits 《Thin solid films》2012,520(11):3878-3883
Transparent conductive oxide films are suitable sensitive layers for gas sensors and biosensors, provided that their intrinsic properties are controlled, notably considering their thickness dependence. The present paper reports on a study of the variation of some physical properties of polycrystalline Sb doped SnO2 films according to the film thickness. Films were deposited onto Si and glass substrates by aerosol pyrolysis. Their thickness was varied in a range of 20-280 nm. The electrical resistivity, the roughness, the optical constant, the microstructure and the texture were investigated. Correlated evolutions of the resistivity and the surface roughness are found in relation with the evolutions of both the microstructure and the texture. Two main successive growth steps were evidenced which are delimited by a critical film thickness. Below this thickness of approximately 100-120 nm, a strong dependence of physical properties with the thickness is evidenced whereas for thicker films no significant change is evidenced. A two-step growth model is proposed to explain this behaviour. This mechanism growth is to be considered in view of the integration of SnO2 films as sensitive layers in biosensors. Notably, in the case of biosensors based on the label-free electrochemical detection of biomolecules, it is recommended to use films with thicknesses ranging above the critical thickness value of 100-120 nm in order to obtain optimized, reproducible and comparable responses of biosensors. 相似文献
18.
Structural characterizations of tin oxide (SnO2) thin films, deposited by plasma-enhanced chemical vapor deposition (PECVD), were investigated with scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that the films are porous, the crystalline structure transforms from crystalline to amorphous phase as deposition temperature changes from 500°C to 200°C, and the chemical component is non-stoichiometric (Sn:O is 1.0716 prepared at 450°C with a value of O2 flow 3.5 l/min). Sheet resistance of the thin films decreases with increasing of deposition temperature. Whereas, sheet resistance increases with increasing of oxygen flow. Tin oxide doped with antimony (SnO2:Sb) thin films prepared by same method have a better selectivity to alcohol than to carbon monoxide; the maximum sensitivity is about 220%. The gas-sensing mechanism of SnO2 thin films is commentated. 相似文献
19.
Transparent conducting fluorine-doped tin oxide (SnO2:F) films have been deposited on glass substrates by pulsed laser deposition. The structural, electrical and optical properties of the SnO2:F films have been investigated as a function of F-doping level and substrate deposition temperature. The optimum target composition for high conductivity was found to be 10 wt.% SnF2 + 90 wt.% SnO2. Under optimized deposition conditions (Ts = 300 °C, and 7.33 Pa of O2), electrical resistivity of 5 × 10− 4 Ω-cm, sheet resistance of 12.5 Ω/□, average optical transmittance of 87% in the visible range, and optical band-gap of 4.25 eV were obtained for 400 nm thick SnO2:F films. Atomic force microscopy measurements for these SnO2:F films indicated that their root-mean-square surface roughness ( 6 Å) was superior to that of commercially available chemical vapor deposited SnO2:F films ( 85 Å). 相似文献
20.
In this paper, we present the results of studies on optimalisation of morphology of the SnO2 thin films grown by RGTO technique for application as gas sensor structures. The Sn thin films were grown on Si(111) wafer and Al2O3 ceramic plate heated in the range 235-295 °C and subsequently oxidized in dry oxygen atmosphere at high temperature, up to 700 °C. Our studies confirmed that the highest surface coverage of Sn droplets can be reached for the substrate temperature of about 265 °C leading to the highest surface-to-volume ratio of SnO2 thin films. It was in a good correlation to the optimal gas sensor response and sensor sensitivity of RGTO SnO2 thin films to nitrogen dioxide NO2. 相似文献