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1.
We established a method for preparation of iridium oxide thin film by the sol-gel dip-coating process where iridium chloride was used as a starting material. The coating solution was prepared by reacting iridium chloride, ethanol and acetic acid. Iridium oxide coating was formed at 2.0 cm/min withdrawing rate. The coating films heat treated at 300°C did not contain impurities. Iridium oxide crystallized at temperatures above 450°C. Both crystalline and amorphous iridium oxide thin films showed electrochromism. The change in transmittance of the crystalline Ir2O3 film is larger than that of the amorphous Ir2O3 under the same experimental conditions. The transmittance of the crystalline thin film (film thickness 200 nm, measured at 400 nm) decreased 13.0% on application of 3 V for 1 s.  相似文献   

2.
Titanium oxide (TiO2) thin films were deposited onto glass substrates by means of spray pyrolysis method using methanolic titanyl acetyl acetonate as precursor solution. The thin films were deposited at three different temperatures namely 350, 400 and 450 °C. As-deposited thin films were amorphous having 100–300 nm thickness. The thin films were subsequently annealed at 500 °C in air for 2 h. Structural, optical and electrical properties of TiO2 thin films have been studied. Polycrystalline thin films with rutile crystal structure, as evidenced from X-ray diffraction pattern, were obtained with major reflexion along (1 1 0). Surface morphology and growth stages based on atomic force microscopy measurements are discussed. Electrical properties have been studied by means of electrical resistivity and thermoelectric power measurements. Optical study shows that TiO2 possesses direct optical transition with band gap of 3.4 eV.  相似文献   

3.
Previous studies have suggested that contamination by carbon of the i-Al62Cu25.5Fe12.5 quasicrystalline phase can cause destabilization of the aperiodic structure. Hence, the possibility of carbon diffusion into AlCuFe quasicrystalline thin films and the possible subsequent degradation of the quasicrystalline structure were investigated at room temperature through to 600 °C. The study shows that a carbon layer deposited on the AlCuFe quasicrystalline thin film did not diffuse into the AlCuFe over the temperature range tested whatever the oxide thickness between carbon and alloy. Moreover, the carbon did not react with any of the alloy elements as has been shown with aluminium in the presence of oxygen. Post-deposition annealing at 600 °C of the amorphous alloy, fabricated by simultaneous electron beam evaporation on an amorphous carbon substrate used for transmission electron microscopy (TEM), also leads to a pure quasicrystalline phase thin film without any carbon diffusion from the substrate.  相似文献   

4.
Highly preferred oriented lead barium titanate (Pb1−x,Bax)TiO3 thin film, with particular emphasis on (Pb0.5,Ba0.5)TiO3, can be obtained by spin-coating on MgO (100) substrate by using the precursor sol, which was synthesized from acetylacetone chelating with titanium isopropoxide and ethylene glycol as a solvent, in the sol-gel process. Film thickness, pyrolysis temperature and heating rate were studied systemically to investigate their influences on the formation of preferred oriented thin films. The highly preferred (001)/(100) oriented thin film could be obtained by the pyrolysis of wet film at 500 °C and annealing at 600 °C at a slow heating rate of 5 °C/min. It is confirmed that the tetragonal perovskite structure of the titanate ceramic decreases with an increase of Ba content in (Pb1−x,Bax)TiO3. The (001)/(100) oriented films were synthesized from all compositions between x = 0.2 and x = 0.8, at a crystallization temperature of 600 °C. In particular, for the Ba content in the range of x = 0.50.6, highly preferred (001)/(100) planes were observed.  相似文献   

5.
Electrochromic properties of nanocrystalline MoO3 thin films   总被引:1,自引:0,他引:1  
Electrochromic MoO3 thin films were prepared by a sol–gel spin-coating technique. The spin-coated films were initially amorphous; they were calcined, producing nanocrystalline MoO3 thin films. The effects of annealing temperatures ranging from 100 °C to 500 °C were investigated. The electrochemical and electrochromic properties of the films were measured by cyclic voltammetry and by in-situ optical transmittance techniques in 1 M LiClO4/propylene carbonate electrolyte. Experimental results showed that the transmittance of MoO3 thin films heat-treated at 350 °C varied from 80% to 35% at λ = 550 nm (ΔT =  45%) and from 86% to 21% at λ ≥ 700 nm (ΔT =  65%) after coloration. Films heat-treated at 350 °C exhibited the best electrochromic properties in the present study.  相似文献   

6.
Amita Verma  Anshu Goyal  R.K. Sharma   《Thin solid films》2008,516(15):4925-4933
The properties of sol–gel derived CeTi2O6 thin films deposited using a solution of cerium chloride heptahydrate and titanium propoxide in ethanol are discussed. The effect of annealing temperature on structural, optical, photoluminescence, photocatalysis and electrochemical characteristics has been examined. Lowest annealing temperature for the formation of crystalline CeTi2O6 phase in these samples is identified as 580 °C. The optical transmittance of the films is observed to be independent of the annealing temperature. The optical energy bandgap of the 600 °C annealed film for indirect transition is influenced by the presence of anatase phase of TiO2 in its structure. Fourier transform infrared spectroscopy investigations have evidenced increased bond strength of the Ti–O–Ti network in the films as a function of annealing temperature. The photoluminescence intensity of the films has shown dependence on the annealing temperature with the films fired at 450 °C exhibiting the maximum photoluminescence activity. The decomposition of methyl orange and eosin (yellow) under UV–visible light irradiation in the presence of crystalline CeTi2O6 films shows the presence of photoactivity in these films. The photocatalytic response of CeTi2O6 films is found to be superior to the TiO2 films. In comparison to crystalline films, the amorphous films have shown superior electrochemical characteristics. The 500 °C annealed amorphous films have exhibited the most appropriate properties for incorporation in electrochromic devices comprising tungsten oxide as the primary electrochromic electrode.  相似文献   

7.
A study of growth, structure, and properties of Eu2O3 thin films were carried out. Films were grown at 500–600 °C temperature range on Si(1 0 0) and fused quartz from the complex of Eu(acac)3·Phen by low pressure metalorganic chemical vapor deposition technique which has been rarely used for Eu2O3 deposition. These films were polycrystalline. Depending on growth conditions and substrates employed, these films had also possessed a parasitic phase. This phase can be removed by post-deposition annealing in oxidizing ambient. Morphology of the films was characterized by well-packed spherical mounds. Optical measurements exhibited that the bandgap of pure Eu2O3 phase was 4.4 eV. High frequency 1 MHz capacitance–voltage (CV) measurements showed that the dielectric constant of pure Eu2O3 film was about 12. Possible effects of cation and oxygen deficiency and parasitic phase on the optical and electrical properties of Eu2O3 films have been briefly discussed.  相似文献   

8.
Thin films of the system xAl2O3–(100 − x)Ta2O5–1Er2O3 were prepared by a sol–gel method and a dip-coating technique. The influences of the composition and the crystallization of the films on Er3+ optical properties were investigated. Results of X-ray diffraction indicated that the crystallization temperature of Ta2O5 increased from 800 to 1000 °C with increased values of x. In crystallized films, the intensities of the visible fluorescence and upconversion fluorescence tend to decrease with an increase in x values, due to the high phonon energy of Al2O3; the strongest fluorescence is observed in a crystallized film for x = 4 heat treated at 1000 °C. In amorphous films obtained by heat treatment at relatively low temperatures the Er3+ fluorescence could not be observed because strong fluorescence from organic residues remaining in the films thoroughly covered the Er3+ fluorescence. On the other hand, the Er3+ upconversion fluorescence in the amorphous films was observed to be stronger than that in the crystallized films. The strongest upconversion fluorescence is observed in an amorphous film for x = 75 heat treated at 800 °C.  相似文献   

9.
Calcium modified lead titanate sol was synthesized using lead acetate trihydrate, calcium nitrate tetrahydrate and titanium tetra-n-butoxide as starting materials, methanol and ethanolamine were selected as solvent and stabilizing or complexing agent, respectively. (Pb0.76Ca0.24)TiO3 thin films were prepared on platinum-coated silicon and fused silica substrates with the solution using the spinning method. The surface morphology and crystal structure, surface compositions and chemical states, electrical and optical properties of the thin films were investigated. The films have good composition homogeneity and thickness uniformity. The dielectric constant and dissipation factor of 1 kHz at room temperature were found to be 280 and 0.027, respectively, for thin films with 0.5 μm thickness annealed at 600°C for 1 h. The remanent polarization and coervive field were 15 μC/cm2 and 64 kV/cm, respectively. The thin films exhibited good optical transmissitivity, and had optical direct transitions. The dispersion relation of refractive index and wavelength followed the single electron oscillation model. The band gap of the film which annealed at 650°C was 3.68 eV. The results also confirmed that ethanolamine was very effective in preparing uniform and dense oxide films, owing to the superior stability of the sols during hydrolytic polycondensation.  相似文献   

10.
A highly oriented FeO thin film was formed from a Fe3O4 thin film containing Fe nanocrystallines by post-annealing at 600°C. Fe3O4 thin films were grown on Si(100) substrates by ion beam sputter deposition under oxygen ambient. The stoichiometry of the iron oxide thin film could be precisely controlled by in situ X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) pattern of the Fe3O4 thin film grown at substrate temperature of 300°C showed a mixed phase of Fe3O4 and Fe nanocrystallines with a preferred orientation (110). However, the mixed phase was converted to a highly oriented FeO(200) phase by post-annealing at 600°C. This could be inverted as a result of Ostwald ripening of the Fe3O4 and Fe nanocrystallines.  相似文献   

11.
The influence of nitrogen on the diffusion barrier properties of amorphous Ni---W films was studied. Nitrogen was introduced into the amorphous Ni---W film by co-sputtering nickel and tungsten in a premixed gas mixture of 90% Ar and 10% N2, resulting in the formation of amorphous Ni30N21W49 film. X-ray analysis indicates a detectable crystallization of the amorphous film after 30 min annealing in vacuum at 600°C, accompanied by the formation of W2N, but backscattering spectrometry (BS) reveals a reaction with silicon only at about 725°C. The Schottky barrier height of this amorphous film on n-Si is stable for 30 min annealing up to at least 550°C. With an aluminum overlayer, BS indicates that an amorphous Ni30N21W49 film effectively prevents the metallurgical interaction between aluminum and silicon for 30 min up to 600°C. The Schottky barrier height of that contact configuration is also stable up to at least 550°C, suggesting that amorphous Ni---N---W films have attractive features as diffusion barriers.  相似文献   

12.
TiO2/SnO2 thin films with different tin atomic percentages were successfully prepared on glass substrates by the spray pyrolysis method from an alcoholic solution of TiO[C5H7O2]2 with different concentrations of SnCl4. The TiO2/SnO2 thin films prepared at 450 °C presented the anatase phase in polycrystalline configuration from %Sn = 0 in the starting solution up to %Sn = 20, at higher tin content the films present an amorphous configuration. The resulting thin films have a homogeneous surface structure with some porosity. The photocatalytical properties of the films were evaluated with the degradation of methylene blue. The products of the degradation reaction were identified by 1H nuclear magnetic resonance and the film properties were studied by atomic force microscopy, scanning electron microscopy, UV–Vis spectroscopy, and X-ray diffraction.  相似文献   

13.
The ultrasonic spray pyrolysis (USP) technique has been employed to deposit tungsten oxide (WO3) thin films. The films were prepared by spraying 0.02 M ammonium metatungstate solution onto amorphous glass substrates kept at 250°C. These films were further annealed at 400°C for different time periods (1–5 h) in air. The films were characterized for structural, electrical and opto-electronic properties. X-ray diffraction technique was used to determine the crystallinity of the WO3 films and identify the phases that form as a function of annealing time. The as-prepared WO3 films were amorphous and crystallize when annealed at 400°C in air for 2 or more hours. From TEM, the grain size and lattice plane spacing are estimated. The films were further characterized by using time resolved microwave conductivity (TRMC) technique and decay time of the photogenerated charge carriers is calculated to be about 154 ns. The concentration and mobility of charge carriers are estimated from thermoelectric power (TEP) measurements.  相似文献   

14.
Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205–300 °C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75–1.80. Calcium oxide films grown without Al2O3 capping layer occurred hygroscopic and converted to Ca(OH)2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al2O3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 °C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO2 growth cycles at 230 and 300 °C. HfCl4 was used as a hafnium precursor. When grown at 230 °C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 °C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca2Hf7O16 or Ca6Hf19O44. At 300 °C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca2Hf7O16. The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8–14.2.  相似文献   

15.
An effective method is developed for low temperature metal oxide deposition through thermal decomposition of metal diketonates in supercritical carbon dioxide (scCO2) solvent. The rates of Al(acac)3 (Aluminum acetyl acetonate) and Ga(acac)3 (Gallium acetyl acetonate) thermal decomposition in scCO2 to form conformal Al2O3 and Ga2O3 thin films on planar surfaces were investigated. The thermal decomposition reaction of Al(acac)3 and Ga(acac)3 was found to be initialized at  150 °C and 160 °C respectively in scCO2 solvent, compared to  250 °C and 360 °C in analogous vacuum-based processes. By measuring the temperature dependence of the growth rates of metal oxide thin films, the apparent activation energy for the thermal decomposition of Al(acac)3 in scCO2 is found to be 68 ± 6 kJ/mol, in comparison with 80–100 kJ/mol observed for the corresponding vacuum-based thermal decomposition reaction. The enhanced thermal decomposition rate in scCO2 is ascribed to the high density solvent which effectively reduces the energy of the polar transition states in the reaction pathway. Preliminary results of thin film deposition of other metal oxides including ZrOx, FeOx, Co2O3, Cr2O3, HfOx from thermal decomposition of metal diketonates or fluorinated diketonates in scCO2 are also presented.  相似文献   

16.
Tantalum oxide films have been deposited by 355 nm pulsed laser ablation of metallic Ta target in O3/O2 ambient. The structure and the composition of as-deposited and annealed films were examined by X-ray diffraction and Fourier transform infrared spectroscopy. The measurements of the current–voltage and capacitance–voltage characteristics of the Al/Ta2O5/Si capacitors were performed to reveal the electrical properties of the Ta2O5 films. The effects of annealing temperature on the characteristics of thin films have been studied. The results suggest that the films annealed above 700°C have the structure of orthorhombic β-Ta2O5, thc annealing treatment at high temperature decreases the bulk trap charge, the border trap, and the interface trap densities of as-deposited films, and improves significantly the dielectric and electrical properties of Ta2O5 film.  相似文献   

17.
Hf(OCH2CH2NMe2)4, [Hf(dmae)4] (dmae=dimethylaminoethoxide) was synthesized and used as a chemical vapor deposition precursor for depositing Hf oxide (HfO2). Hf(dmae)4 is a liquid at room temperature and has a moderate vapor pressure (4.5 Torr at 80 °C). It was found that HfO2 film could be deposited as low as 150 °C with carbon level not detected by X-ray photoelectron spectroscopy. As deposited film was amorphous but when the deposition temperature was raised to 400 °C, X-ray diffraction pattern showed that the film was polycrystalline with weak peak of monoclinic (020). Scanning electron microscope analysis indicated that the grain size was not significantly changed with the increase of the annealing temperature. Capacitance–voltage measurement showed that with the increase of annealing temperature, the effective dielectric constant was increased, but above 900 °C, the effective dielectric constant was decreased due to the formation of interface oxide. For 500 Å thin film, the dielectric constant of HfO2 film annealed at 800 °C was 20.1 and the current–voltage measurements showed that the leakage current density of the HfO2 thin film annealed at 800 °C was 2.2×10−6 A/cm2 at 5 V.  相似文献   

18.
This paper reports on the first sol–gel thin film preparation of a new optically active compound: Er2Ti2O7 (ETO). Optical, microstructural and spectroscopic properties of ETO films annealed in a temperature range 300–1000°C are studied. This work shows that the porosity and microstructure of ETO films depend closely on the heat-treatment temperature. Photoluminescence (PL) has been observed for films heat-treated at 600°C or more. The PL decay appears strongly influenced by quenching effects. For thin films treated at 600°C, quenching is essentially due to the presence of hydroxyl groups. After heat-treatment at 800°C or more, quenching can be explained by the high concentration of erbium atoms and by their distribution in the ETO lattice.  相似文献   

19.
Pt-PtOx thin films were prepared on Si(100) substrates at temperatures from 30 to 700°C by reactive r.f. magnetron sputtering with platinum target. Deposition atmosphere was varied with O2/Ar flow ratio. The deposited films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Resistively of the deposited films was measured by d.c. four probe method. The films mainly consisted of amorphous PtO and Pt3O4 (or Pt2O3) below 400°C, and amorphous Pt was increased in the film as a deposition temperature increased to 600°C. When deposition temperature was thoroughly increased, (111) oriented pure Pt films were formed at 700°C. Compounds included in the films strongly depended on substrate temperature rather than O2/Ar flow ratio. Electrical resistivity of Pt-PtOx films was measured to be from the order of 10−1 Ω cm to 10−5 Ω cm, which was related to the amount of Pt phase included in the deposited films.  相似文献   

20.
A series of 0.2–0.6 μm thick SnOx films were deposited onto borosilicate and sodalime silica glass substrates by atmospheric plasma discharge chemical vapor deposition at 80 °C. SnOx films deposited from monobutyltin trichloride contained a large percentage of SnCl2:2H2O, and therefore were partially soluble in water. SnOx coatings deposited from tetrabutyltin were not soluble in water or organic solvents, had good adhesion even at growth rates as high as 2.3 nm/s, had high transparency of  90% and electrical resistivity of 107 Ω cm. As-grown tin oxide coatings were amorphous with a small concentration of SnO2, SnO and Sn crystalline phases as determined by grazing angle X-ray diffraction and X-ray photoelectron spectroscopy measurements. Upon annealing in air at 600 °C the resistivity of SnOx films decreased to 5–7 Ω cm. Furthermore, optical and X-ray measurements indicated that SnOx was converted into SnO2 (cassiterite) with a direct band gap of 3.66 eV. Annealing of as-grown SnOx films in vacuum at 340 °C led to formation of the p-type conductor SnO/SnOx. The indirect band gap of SnO was calculated from the optical spectra to be 0.3 eV.  相似文献   

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