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1.
We prepared Cr-doped titanium dioxide (TiO2) films by oxygen (O2) cluster ion beam assisted deposition method, and investigated photocatalytic properties of the films as well as crystallographic property, optical property and surface morphology. The films prepared at a substrate temperature below 200 °C were found to be amorphous from the X-ray diffraction measurement. For the substrate temperatures such as 300 °C and 400 °C, the films exhibited rutile and/or anatase structures. The film surface measured by the atomic force microscope (AFM) was smooth at an atomic level. Furthermore, the optical band gap decreased with increase of Cr-composition, and it was approximately 3.3 eV for the non-doped films, 3.2 eV for the 1% Cr-doped films and 3.1 eV for the 10% Cr-doped films, respectively. With regard to the photocatalytic properties of the Cr-doped TiO2 films, we measured the change of contact angle as well as the photocatalytic degradation of methylene blue by the UV light irradiation. Compared with the non-doped films, the 1% Cr-doped films prepared at a substrate temperature of 400 °C showed high degradation efficiency. In addition, the contact angle of the 1% Cr-doped films with an initial value of 60° decreased to 10° by the UV light irradiation for 20 min, and the films exhibited the predominant properties of photocatalytic hydrophilicity even for the UV light irradiation with longer wavelengths. 相似文献
2.
Anatase titanium dioxide (TiO2) thin films with high photocatalytic activity have been prepared with deposition rates as high as 16 nm/min by a newly developed vacuum arc plasma evaporation (VAPE) method using sintered TiO2 pellets as the source material. Highly transparent TiO2 thin films prepared at substrate temperatures from room temperature to 400 °C exhibited photocatalytic activity, regardless whether oxygen (O2) gas was introduced during the VAPE deposition. The highest photocatalytic activity and photo-induced hydrophilicity were obtained in anatase TiO2 thin films prepared at 300 °C, which correlated to the best crystallinity of the films, as evidenced from X-ray diffraction. In addition, a transparent and conductive anatase TiO2 thin film with a resistivity of 2.6 × 10− 1 Ω cm was prepared at a substrate temperature of 400 °C without the introduction of O2 gas. 相似文献
3.
Microstructure and hydrophilicity of nano-titanium dioxide (TiO2) thin films, deposited by radio frequency magnetron sputtering, annealed at different temperatures, were studied by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle methods. It is found that the crystal phase transforms from amorphous to rutile structure with increase of annealing temperature from room temperature to 800 °C. It is also indicated that the organic contaminants on the surface of the films can be removed and the oxygen vacancies can be reduced by the annealing treatment. Annealed at the temperature below 300 °C, amorphous TiO2 thin films show rather poor hydrophilicity, and annealed at the temperature range from 400 to 650 °C, the super hydrophilicity anatase of TiO2 thin films can be observed. However, when the annealing temperature reaches 800 °C, the hydrophilicity of the films declines mainly derived from the appearance of rutile. 相似文献
4.
The gel-derived TiO2 and P-TiO2 transparent films coated on fused-SiO2 substrates were prepared using a spin-coating technique. Effects of phosphorus dopants and calcination temperature on crystal structure, crystallite size, microstructure, light transmittance and photocatalytic activity of the films were investigated. By introducing P atoms to Ti-O framework, the growth of anatase crystallites was hindered and the crystal structure of anatase-TiO2 could withstand temperature up to 900 °C. The photocatalytic activities of the prepared films were characterized using the characteristic time constant (τ) for the photocatalytic reaction. The titania film with a smaller τ value possesses a higher photocatalytic ability. After exposing to 365-nm UV light for 12 h, the P-TiO2 films calcined between 600 °C and 900 °C can photocatalytically decomposed ≥ 84 mol% of the methylene blue in water with corresponding τ ≤ 7.1 h, which were better than the pure TiO2 films prepared at the same calcination temperature. 相似文献
5.
TaOxNy thin films were prepared using DC reactive sputtering of Ta target with the variation of (O2 + N2)/Ar ratio, followed by rapid thermal annealing (RTA) at 800 °C for 5 min. During RTA, the amorphous structure of the as-deposited films would transform to crystallized phases that might contain either TaON, or Ta2O5, or both. With the increase of (O2 + N2)/Ar ratio, Ta2O5 phase becomes more dominant, while TaON was formed in an opposite way. Elemental analysis also shows the same trend. Hydrophilicity and optical properties of these films were found to be dependent on phases formed after annealing. The optical band gap was measured and calculated to be in the range of 2.43 eV (510 nm) to 3.94 eV (315 nm). The films with low band gap values exhibited super hydrophilicity behavior under visible light irradiation, mainly due to their light absorption had been extended to visible light range. Clearly, it was due to the existence of TaON phase. 相似文献
6.
Influences of the temperature (Ts) for spray pyrolysis deposition of TiO2 blocking layer (BL) using titanium diisopropoxide bis(acetylacetonate) (TAA) as a precursor and the temperature (Tp) for post-annealing of the BL films on the resulting BL film morphology and photovoltaic performance of solid-state dye-sensitized solar cells (SDSC) are investigated. A Ts ranging from 300 to 400 °C is found preferable for the formation of BL films with smooth surface and dense grain packing. A Ts lower than 300 °C results in insufficient decomposition of the TAA precursor and is unable to form smooth BL films, while a Ts over 400 °C leads to loosely packed grain in BL films. Power conversion efficiency (PCE) of ~ 4.0% is obtained for SDSC devices with BL films prepared at a Ts in the range of 300-450 °C. High temperature post-annealing (Tp = 500-550 °C) of the BL films prepared at a low Ts, such as 300 °C, can improve the PCE up to 4.6%. The improvements are considered due to the higher purity, increased crystallinity, and retained high grain packing density of the post-annealed BL films, which facilitate charge transport and suppress charge recombination. 相似文献
7.
Atomic layer deposition (ALD) of ZnS films utilizing diethylzinc and in situ generated H2S was performed over a temperature range of 60 °C-400 °C. This method for generating H2S in situ was developed to eliminate the need to store high pressure H2S gas. The H2S precursor was generated by heating thioacetamide to 150 °C in an inert atmosphere, producing acetonitrile and H2S as confirmed with mass spectroscopy. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with X-ray diffraction, transmission electron microscopy, ellipsometry, atomic force microscopy, scanning electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The results show a growth rate that monotonically decreases with temperature, and films that are stoichiometric in Zn and S. The root mean square roughness of the films increases with temperature above 100 °C. A change in crystal phase begins at ∼ 300 °C. The band gap is dependent on the crystal phase and is estimated to be 3.6-4 eV. 相似文献
8.
Titanium dioxide (TiO2) thin films were prepared on Galvanized Iron (GI) substrate by plasma-enhanced atomic layer deposition (PE-ALD) using tetrakis-dimethylamido titanium and O2 plasma to investigate the photocatalytic activities. The PE-ALD TiO2 thin films exhibited relatively high growth rate and the crystal structures of TiO2 thin films depended on the growth temperatures. TiO2 thin films deposited at 200 °C have amorphous phase, whereas those with anatase phase and bandgap energy about 3.2 eV were deposited at growth temperature of 250 °C and 300 °C. From contact angles measurement of water droplet, TiO2 thin films with anatase phase and Activ™ glass exhibited superhydrophilic surfaces after UV light exposure. And from photo-induced degradation test of organic solution, anatase TiO2 thin films and Activ™ glass decomposed organic solution under UV illumination. The anatase TiO2 thin film on GI substrate showed higher photocatalytic efficiency than Activ™ glass after 5 h UV light exposure. Thus, we suggest that the anatase phase in TiO2 thin film contributes to both superhydrophilicity and photocatalytic decomposition of 4-chlorophenol solution and anatase TiO2 thin films are suitable for self-cleaning applications. 相似文献
9.
ZnS thin films were deposited by spray pyrolysis method on glass substrates. Diffusion of Ag in ZnS thin films was performed in the temperature range 80-400 °C under a nitrogen atmosphere. The diffusion of Ag is determined with XRF, and the obtained concentration profile allows to calculate the diffusion coefficient. The temperature dependence of Ag diffusion coefficient is determined by the equation D = 8 × 10− 9 exp(− 0.10 eV / kT). It was found that the as-grown undoped high resistive n-type ZnS thin films were converted to the p-type upon Ag doping with a slight increase in resistivity only by rapid thermal annealing at 400 °C in N2 atmosphere. In addition, the band gap of the p-type film was decreased as compared with the undoped sample annealed under the same conditions. The results were attributed to the migration of Ag atoms in polycrystalline ZnS films by means of both along intergrain surfaces and intragrain accompanied by interaction with native point defect. 相似文献
10.
BiFeO3 (BFO) films were grown on LaNiO3-coated Si substrate by a RF magnetron sputtering system at temperatures in the range of 300-700 °C. X-ray reflectivity and high-resolution diffraction measurements were employed to characterize the microstructure of these films. For a substrate temperature below 300 °C and at 700 °C only partially crystalline films and completely randomly polycrystalline films were grown, whereas highly (001)-orientated BFO film was obtained for a substrate temperature in the range of 400-600 °C. The crystalline quality of BFO thin films increase as the deposition temperature increase except for the film deposited at 700 °C. The fitted result from X-ray reflectivity curves show that the densities of the BFO films are slightly less than their bulk values. For the BFO films deposited at 300-600 °C, the higher the deposition temperature, the larger the remnant polarization and surface roughness of the films present. 相似文献
11.
Z.H. ZhengP. Fan T.B. ChenZ.K. Cai P.J. LiuG.X. Liang D.P. ZhangX.M. Cai 《Thin solid films》2012,520(16):5245-5248
N-type bismuth telluride (Bi2Te3) thermoelectric thin films were deposited on BK7 glass substrates by ion beam sputtering method. Various substrate temperatures were tried to obtain optimal thermoelectric performance. The influence of deposition temperature on microstructure, surface morphology and thermoelectric properties was investigated. X-ray diffraction shows that the films are rhombohedral with c-axis as the preferred crystal orientation when the deposition temperature is above 250 °C. All the films with single Bi2Te3 phase are obtained by comparing X-ray diffraction and Raman spectroscopy. Scanning electron microscopy result reveals that the average grain size of the film is larger than 500 nm when the deposition temperature is above 300 °C. Thermoelectric properties including Seebeck coefficient and electrical conductivities were measured at room temperature, respectively. It is found that Seebeck coefficients increase from − 28 μV k− 1 to − 146 μV k− 1 and the electrical conductivities increase from 1.87 × 103 S cm− 1 to 3.94 × 103 S cm− 1 when the deposition temperature rose to 250 °C and 300 °C, respectively. An optimal power factor of 6.45 × 10− 3 Wm− 1 K− 2 is gained when the deposition temperature is 300 °C. The thermoelectric properties of bismuth telluride thin films have been found to be strongly enhanced by increasing the deposition temperature. 相似文献
12.
Optical and morphological characterization of photocatalytic TiO2 thin films doped with silver 总被引:1,自引:0,他引:1
Silver-doped titanium dioxide thin films were deposited on glass substrates by the sol-gel process. Undoped films and films doped with 1 and 3 mol% Ag were annealed at 100 or 500 °C. The optical and morphological properties of the films were analyzed by optical absorption spectroscopy and scanning electron microscopy. Additionally, the films were evaluated for their ability to degrade methylene blue. It was found that the photocatalytic activity is barely sensitive to silver doping for films annealed at 100 °C, whereas the effect of silver resulted in enhanced photocatalytic activity for films annealed at 500 °C. For the latter annealing temperature, the photocatalytic activity increased with increasing Ag doping concentration. 相似文献
13.
Anatase titanium dioxide (TiO2) thin films are prepared by DC reactive magnetron sputtering using Ti target as the source material. In this work argon and oxygen are used as sputtering and reactive gas respectively. DC power is used at 100 W per 1 h. The distance between the target and substrate is fixed at 4 cm. The glass substrate temperature value varies from room temperature to 400 °C. The crystalline structure of the films is determined by X-ray diffraction analysis. All the films deposited at temperatures lower than 300 °C were amorphous, whereas films obtained at higher temperature grew in crystalline anatase phase. Phase transition from amorphous to anatase is observed at 400 °C annealing temperature. Transmittances of the TiO2 thin films were measured using UV-visible NIR spectrophotometer. The direct and indirect optical band gap for room temperature and substrate temperature at 400 °C is found to be 3.50, 3.41 eV and 3.50, 3.54 eV respectively. The transmittance of TiO2 thin films is noted higher than 75%. A comparison among all the films obtained at room temperature showed a transmittance value higher for films obtained at substrate temperature of 400 °C. The morphology of the films and the identification of the surface chemical stoichiometry of the deposited film at 400 °C were studied respectively, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface roughness and the grain size are measured using AFM. 相似文献
14.
Amanpal Singh Dinesh KumarP.K. Khanna Anuj KumarMukesh Kumar Mohit Kumar 《Thin solid films》2011,519(17):5826-5830
The magnesium doped zinc oxide is a promising optical material to enhance the luminescence for possible application in solid state lighting. Magnesium doped zinc oxide thin films (Zn0.85Mg0.15O) were deposited by sol-gel route on p-type silicon and annealed at different temperatures in oxygen environment for an hour. The doping of magnesium in zinc oxide was confirmed by X-Ray diffraction and the samples were found to have wurtzite crystal structure with (002) preferred orientation. The films were characterized by Hall-effect, atomic force microscopy, UV-VIS spectroscopy, photoluminescence (PL) and work function measurements. The different studies exhibited an anomalous behavior for the film annealed at 900 °C. The Hall effect, work function measurements and UV-VIS spectroscopy indicated that the resistivity, work function and optical band gap increased as a function of annealing temperature (from 300 °C to 700 °C) however these parameters were found to decrease for the films annealed above 700 °C. The particle size increased with the annealing but for the samples annealed at 900 °C, the shape of the grains changed and became elongated like fibers as observed by the atomic force microscopy. The PL measurements displayed the existence of oxygen vacancies defects for the samples annealed at and above 600 °C. The possible mechanism for this anomaly has been discussed in this work. 相似文献
15.
Thickness dependence of microstructures and magnetic properties for CoPt/Ag nanocomposite thin films
Ag underlayer (30 nm) has improved the degree of ordering and perpendicular magnetic anisotropy of CoPt films (7.5-10 nm). After annealing at 600 °C and 700 °C, the perpendicular coercivity of CoPt/Ag films has been raised as the thicknesses of CoPt layers are increased. The magnetic easy axis of CoPt/Ag films would change from a random orientation to an out-of-plane orientation. It is found that Ag underlayer with thickness of 30 nm can improve the perpendicular magnetic properties of CoPt layers with thicknesses in the range of 7.5-10 nm. The CoPt/Ag films would be a candidate for perpendicular magnetic recording media. 相似文献
16.
Yttrium-doped hafnium oxide (YDH) films have been produced by sputter-deposition by varying the growth temperature (Ts) from room-temperature (RT) to 400 °C. The electrical and optical properties of YDH films have been investigated. Structural studies indicate that YDH films grown at Ts = RT − 200 °C were amorphous and those grown at 300-400 °C are nanocrystalline. The crystalline YDH films exhibit the high temperature cubic phase of HfO2. Spectrophotometry analysis indicates that all the YDH films are transparent. The band gap of YDH films was found to be in the range of 6.20-6.28 eV. Frequency variation of frequency dependent resistivity indicates the hopping conduction mechanism operative in YDH films. While the electrical resistivity (ρac) is ~ 1 Ω-m at low frequencies (100 Hz), ρac decreases to ~ 10− 4 Ω-cm at higher frequencies (1 MHz). 相似文献
17.
Jun-ichi Nomoto 《Thin solid films》2010,518(11):2937-1406
This paper compares in detail the resistivity behavior of transparent conducting Al-doped and Ga-doped ZnO (AZO and GZO) thin films for use in an air environment at high temperatures. AZO and GZO thin films with thicknesses in the range from approximately 30 to 100 nm were prepared on glass substrates at a temperature of 200 °C by rf superimposed dc or conventional dc magnetron sputtering deposition, pulsed laser deposition or vacuum arc plasma evaporation techniques. In heat-resistance tests, the resistivity was measured both before and after heat tests for 30 min in air at a temperature up to 400 °C. The resistivity stability of AZO thin films was found to be always lower than that of GZO thin films prepared with the same thickness under the same deposition conditions, regardless of the deposition technique. However, the resistivity of all AZO and GZO thin films prepared with a thickness above approximately 100 nm was stable when heat tested at a temperature up to approximately 250 °C. It was found that the resistivity stability in both GZO and AZO thin films is dominated by different mechanisms determined by whether the thickness is below or above approximately 50 nm. With thicknesses above approximately 100 nm, the increase in resistivity found in GZO and AZO films after heat testing at a temperature up to 400 °C exhibited different characteristics that resulted from a variation in the behavior of Hall mobility. 相似文献
18.
W.W. Liu B. Yao Y.F. Li B.H. Li C.X. Shan J.Y. Zhang X.W. Fan 《Thin solid films》2010,518(14):3923-3815
Undoped ZnO films were grown on a c-plane sapphire by plasma-assisted molecular-beam epitaxy technique, and subsequently annealed at 200-500 °C with steps of 100 °C in water vapour and hydrogen ambient, respectively. It is found that the c-axis lattice constant of the ZnO films annealed in hydrogen or water vapour at 200 °C increases sharply, thereafter decreases slowly with increasing annealing temperature ranging from 300 °C to 500 °C. The stress in the as-grown ZnO films was more easily relaxed in water vapour than in hydrogen ambient. Interestingly, the controversial luminescence band at 3.310 eV, which is often observed in photoluminescence (PL) spectra of the ZnO films doped by p-type dopants, was observed in the PL spectra of the annealed undoped ZnO films and the PL intensity increases with increasing annealing temperature, indicating that the 3.310 eV band is not related to p-type doping of ZnO films. The electron concentration of the ZnO films increases sharply with increasing annealing temperature when annealed in hydrogen ambient but decreases slowly when annealed in water vapour. The mechanisms of the effects of annealing ambient on the properties of the ZnO films are discussed. 相似文献
19.
We report the structural and optical properties of nanocrystalline thin films of vanadium oxide prepared via evaporation technique on amorphous glass substrates. The crystallinity of the films was studied using X-ray diffraction and surface morphology of the films was studied using scanning electron microscopy and atomic force microscopy. Deposition temperature was found to have a great impact on the optical and structural properties of these films. The films deposited at room temperature show homogeneous, uniform and smooth texture but were amorphous in nature. These films remain amorphous even after postannealing at 300 °C. On the other hand the films deposited at substrate temperature TS > 200 °C were well textured and c-axis oriented with good crystalline properties. Moreover colour of the films changes from pale yellow to light brown to black corresponding to deposition at room temperature, 300 °C and 500 °C respectively. The investigation revealed that nanocrystalline V2O5 films with preferred 001 orientation and with crystalline size of 17.67 nm can be grown with a layered structure onto amorphous glass substrates at temperature as low as 300 °C. The photograph of V2O5 films deposited at room temperature taken by scanning electron microscopy shows regular dot like features of nm size. 相似文献
20.
Jun-Won JangJae-Woo Park 《Thin solid films》2011,520(1):193-198
In this work, a combination of oxygen plasma and rapid thermal annealing was suggested in order to oxidize the surface of titanium into TiO2. A plasma was formed by employing pure oxygen at 150 W, 300 W, and 400 W under a pressure of 7.5 to 8.5 Pa for 5 to 10 min. The TiO2 was then subjected to rapid thermal annealing (RTA) at a temperature of 400 to 500 °C for 1 min. From the attained results, an RF power of 300 W for 5 min was observed to be sufficient to produce an optimal photocatalytic TiO2 film. Optimal conditions were confirmed by additional experiments involving humic acid (HA) degradation of the TiO2 films. When compared to a traditional TiO2 film, a TiO2 film prepared with an oxygen-plasma treatment and RTA system exhibited improved photocatalytic capability for HA photodegradation in an aqueous solution. Therefore, this process proposed in this work can be an excellent alternative to the traditional method for fabricating photocatalytic TiO2 films. 相似文献