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1.
The structural properties of a potassium lithium niobate (KLN; K 3Li 2Nb 5O 15) thin film deposited by rf-magnetron sputtering on a Pt/Ti/SiO 2/Si(100) substrate were investigated. The crystalline structures of the Pt under layer and KLN thin films were examined using θ-2 θ, θ-rocking, and mesh scan X-ray diffraction (XRD). The XRD results revealed that the Pt under layer was a strong (111) direction orientated poly crystal. Unlike the Pt under layer film, the KLN(001) peak was found to consist of two separate peaks, one with a broad full width half maximum (FWHM) and the other with a narrow FWHM, indicating that the KLN film had a single crystalline structure. The surface and cross-section morphology were investigated using a scanning electron microscope (SEM). Accordingly, from the results of the SEM and XRD experiments, it was concluded that the KLN film was composed of small single crystals, which had a four-fold symmetry morphology with a c-axis normal to the substrate. 相似文献
2.
AgGaS 2 (AGS) thin films were deposited onto glass substrates by sequential thermal evaporation of AgGaS 2 single crystalline powder and excess silver (Ag) interlayer. Systematic optimization to obtain single phase AgGaS 2 thin films was carried out by changing the thickness of the excess silver layer. The structure and composition of as-grown and annealed films were studied by means of X-ray diffraction and energy dispersive X-ray analysis, respectively. The optical properties of AGS thin films determined by transmittance and reflection measurements showed that they had quite high absorption coefficient with the values around 10 4 (cm −1). The calculated band gap values were found to be between 2.30 and 2.75 eV depending on annealing temperature. The refractive index ( n) and extinction coefficient ( k) of the films were determined by the envelope method. Finally, photo-electrical measurements under different illumination intensities were carried out, and different sensitizing and recombination centers were defined. 相似文献
3.
Transparent and crack-free Bi 2Ti 2O 7 thin films with strong (111) orientation were successfully prepared on n-Si(100) by chemical solution deposition (CSD) using bismuth nitrate and titanium butoxide as starting materials. The structural properties were studied by X-ray diffraction. The dielectric constant at 100 kHz at room temperature was 118 and loss factor was 0.074, for a 0.4-μm-thick film annealed at 500°C for 30 min. The leakage current density was 4.06×10 −7 A/cm 2 at an applied voltage of 15 V. 相似文献
4.
In this study, CuFeO 2 thin films were deposited onto quartz substrates using a sol-gel and a two-step annealing process. The sol-gel-derived films were annealed at 500 °C for 1 h in air and then annealed at 600 to 800 °C for 2 h in N 2. X-ray diffraction patterns showed that the annealed sol-gel-derived films were CuO and CuFe 2O 4 phases in air annealing. When the films were annealed at 600 °C in N 2, an additional CuFeO 2 phase was detected. As the annealing temperature increased above 650 °C in N 2, a single CuFeO 2 phase was obtained. The binding energies of Cu-2p 3/2, Fe-2p 3/2, and O-1s were 932.5 ± 0.1 eV, 710.3 ± 0.2 eV and 530.0 ± 0.1 eV for CuFeO 2 thin films. The chemical composition of CuFeO 2 thin films was close to its stoichiometry, which was determined by X-ray photoelectron spectroscopy. Thermodynamic calculations can explain the formation of the CuFeO 2 phase in this study. The optical bandgap of the CuFeO 2 thin films was 3.05 eV, which is invariant with the annealing temperature in N 2. The p-type characteristics of CuFeO 2 thin films were confirmed by positive Hall coefficients and Seebeck coefficients. The electrical conductivities of CuFeO 2 thin films were 0.28 S cm − 1 and 0.36 S cm − 1 during annealing at 650 °C and 700 °C, respectively, in N 2. The corresponding carrier concentrations were 1.2 × 10 18 cm − 3 (650 °C) and 5.3 × 10 18 cm − 3 (700 °C). The activation energies for hole conduction were 140 meV (650 °C) and 110 meV (700 °C). These results demonstrate that sol-gel processing is a feasible preparation method for delafossite CuFeO 2 thin films. 相似文献
5.
Titanium dioxide thin films were deposited by Metallorganic Chemical Vapor Deposition at substrate temperatures ranging from 250 °C to 450 °C over soda lime glass and indium tin oxide coated glass substrates. X-ray diffraction studies show that films have a crystalline anatase structure at all the deposition temperatures. Particle size decreases and texture changes with the increase in substrate temperature. X-ray photoelectron spectroscopy confirms the appearance of a new well resolved state in the core level of Ti 2p spectrum shifted by 1.16 eV to lower binding energy due to the reduction of Ti + 4 to Ti + 3 upon litheation. Chronoamperometery, cyclic voltammetery and in situ UV-Vis spectrophotometeric studies were carried out on the prepared samples. Particle size and crystallinity control the electrochromic performance. The 350 °C film shows the highest ion storage capacity and the highest optical modulation along with an appreciable band gap broadening. 相似文献
6.
Thin films of nanocrystalline SnS 2 on glass substrates were prepared from solution by dip coating and then sulfurized in H 2S (H 2S:Ar = 1:10) atmosphere. The films had an average thickness of 60 nm and were characterized by X-ray diffraction studies, scanning electron microscopy, EDAX, transmission electron microscopy, UV-vis spectroscopy, and Raman spectroscopy. The influence of annealing temperature (150-300 °C) on the crystallinity and particle size was studied. The effect of CTAB as a capping agent has been tested. X-ray diffraction analysis revealed the polycrystalline nature of the films with a preferential orientation along the c-axis. Optical transmission spectra indicated a marked blue shift of the absorption edge due to quantum confinement and optical band gap was found to vary from 3.5 to 3.0 eV with annealing temperature. Raman studies indicated a prominent broad peak at ∼314 cm −1, which confirmed the presence of nanocrystalline SnS 2 phase. 相似文献
7.
The electrical and optical properties of silver indium selenide thin films prepared by co-evaporation have been studied. X-ray diffraction indicates that the as prepared films were polycrystalline in nature. The lattice parameters were calculated to be a=0.6137 and b=1.1816 nm. Composition was determined from energy dispersive analysis of X-ray. Silver indium selenide thin films were also prepared by bulk evaporation of powdered sample for comparative study. They have an optical band gap ( Eg) of 1.25 eV and it is a direct allowed transition. Refractive index ( n) and extinction coefficient ( k) were calculated from absorption and reflection spectra. Steady-state photoconductivity was measured from 300 to 400 K. Carrier lifetime was calculated from transient photoconductivity measurements at room temperature at different intensities of illumination. 相似文献
8.
In this paper, we reported on an approach to prepare tin disulfide (SnS 2) thin films on soda-lime glass substrates by vacuum thermal evaporation using SnS 2 powders as a source. The influence of annealing on the chemical composition, crystal structure, surface morphology, and optical band gap of the SnS 2 thin films was systemically investigated. The as-grown SnS 2 thin film was amorphous, homogeneous, smooth, nearly stoichiometric, with no pinhole and crack free, and with an optical band gap of 2.41 eV. After the SnS 2 thin film was annealed at 300 °C, the crystallization of SnS 2 was demonstrated by X-ray diffraction and scanning electron microscope with a characteristic of a preferred orientation along (001) plane with hexagonal phase and the sheet appearance of the SnS 2 crystals. At the annealing temperature of 350 °C, some SnS 2 crystallites and a few pinholes appeared on the surface of the SnS 2 thin films, though the SnS 2 thin film was not oxidized. When the annealing temperature was increased to 400 °C, SnS 2 was gradually oxidized into an approximate spherical shape of SnO 2 from the top to the bottom of the SnS 2 thin film by trace O 2 in the furnace. Therefore, our experiment suggested that the annealing temperature of the SnS 2 thin film using the vacuum thermal evaporation should not be over 300 °C as a window layer in compound thin film solar cells. 相似文献
9.
For the first time, In 2S 3 films composed of nano-/microflakes were fabricated on fluorine-doped tin oxide (FTO) substrate using a simple and effective hydrothermal method. The structure, composition and morphology were examined by X-ray diffraction, energy-dispersive X-ray spectroscopy and field emission scanning electron microscopy. It was found that the reaction time, reaction temperature and the molar ratio of the reactants play key roles in controlling the final morphologies. The possible growth mechanism for the formation of In 2S 3 thin films was proposed. And the optical and photoelectrochemical properties were also investigated. In addition, In 2O 3 films were obtained by annealing the In 2S 3 precursor films in air at 500 °C. 相似文献
10.
Ge 0.7Mn 0.3 thin films were fabricated on Al 2O 3 (0001) and glass substrates at growth temperatures ranging from room temperature to 500 °C by a radio frequency magnetron sputtering. We found that the Ge 0.7Mn 0.3 thin films showed a polycrystalline-to-amorphous transition at about 360 °C, and the ferromagnetic transition temperature of each thin film depends on its structure — crystalline or amorphous states. Particularly, the Ge 0.7Mn 0.3 thin films showed room temperature ferromagnetism when they were fabricated at temperatures above the crystallization temperature. 相似文献
11.
Praseodymium-substituted bismuth titanate (Bi 3.2Pr 0.8Ti 3O 12, BPTO) thin films were successfully deposited on Pt(111)/Ti/SiO 2/Si(100) substrates by spin coating with a sol-gel technology and rapid thermal annealing. The effects of annealing atmospheres (vacuum, ambient atmosphere and oxygen) on the growth and properties of thin films were investigated. The results show that the intensity of the (117) diffraction peak of Bi 3.2Pr 0.8Ti 3O 12 film annealed in oxygen is stronger than those annealed in ambient atmosphere and vacuum. The XRD spectra demonstrated that a highly (117) orientation could be obtained when the Bi 3.2Pr 0.8Ti 3O 12 thin film was annealed in an oxygen-sufficient environment. The BPTO thin films annealed in oxygen atmosphere exhibits the maximum remanent polarization (2 Pr) of 49 μC/cm 2 and a low coercive field (2 Ec) of 130 kV/cm, fatigue free characteristics up to ≧ 10 11 switching cycles. These results indicate that the BPTO thin film is useful in nonvolatile ferroelectric random access memory applications. 相似文献
12.
Molybdenum sulphide was cathodically electrodeposited from aqueous solutions of sodium tetrathiomolybdate. The as-deposited films were X-ray amorphous with a composition, measured by microprobe analysis, close to MoS 2. Annealing these films in Ar resulted in highly-textured films of MoS 2 with the van der Waals planes parallel to the substrate. A small expansion in the c spacing of the annealed films was explained by the presence of oxygen in the crystals. A direct bandgap of 1.78 eV was found for the annealed films. 相似文献
13.
The properties of sol–gel derived CeTi 2O 6 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 CeTi 2O 6 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 TiO 2 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 CeTi 2O 6 films shows the presence of photoactivity in these films. The photocatalytic response of CeTi 2O 6 films is found to be superior to the TiO 2 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
14.
Atomic Layer Deposition has been used to deposit titanium dioxide thin films on soda-lime glass substrates. A series of films with thicknesses from 2.6 to 260 nm has been created and the film structure has been studied with X-ray diffraction. It has been observed that at a reaction temperature of 350 °C, titanium dioxide thin films initially grow as anatase but after a certain thickness, growth continues as rutile. The photoactivity and photocatalytic activity of the films have been found to reach their maximum at a film thickness of 15 nm. At this thickness, the film structure shows a small fraction of rutile crystallites in a largely anatase matrix indicating that both crystal phases are necessary for the maximum activity. 相似文献
15.
Amorphous Ga 20S 75Sb 5 and Ga 20S 40Sb 40 thin films were prepared onto glass substrates by using thermal evaporation method. The effect of annealing (under vacuum) at different temperatures on the optical parameters was investigated in the temperature range 373-593 K. The optical absorption coefficient ( α) for the as-deposited and annealed films were calculated from the reflectance and transmittance measurements in the range 190-900 nm. X-Ray diffraction indicates that the as-deposited films and those annealed up to the glass transition temperature ( Tg) exhibit amorphous state. On annealing above the glass transition temperature these films show a polycrystalline structure. Analysis of the optical absorption data indicates that the optical band gap Egopt of these films obeys Tauc's relation for the allowed non-direct transition. It was found that the optical band gap Egopt increases with annealing temperature up to Tg, whereas above Tg there is a remarkable decrease. The obtained results were interpreted on the basis of amorphous- crystalline transformation. 相似文献
16.
Cu/TiO 2 composite films were prepared at low temperature on glass substrates by a photodeposition method. Films were deposited by irradiating the substrate while in contact with an aqueous TiO 2 suspension containing copper(II) nitrate and ethanol. Cu/TiO 2 composite films of 500 nm in thickness were deposited at room temperature after a short irradiation time (15 min) with a 125 W mercury vapour lamp. According to scanning electron microscopy observations, the obtained films were homogeneous and porous. Energy dispersive X-ray spectroscopy analysis revealed a 3:1 Cu:Ti atomic ratio. Grazing angle X-ray diffraction analysis showed that the films contained Cu and TiO 2 as major components and Cu 2O as a minor component. Heat treatment at 400 °C in air for a period of 3 h transformed the initial material into a CuO/TiO 2 composite, improved the adhesion to the substrate and favoured a more regular distribution of copper oxide according to backscattering micrographs. 相似文献
17.
In this work, we study the crystallization and electrical resistivity of the formed oxides in a Cu/SiO 2/Si thin film after thermal oxidation by ex-situ annealing at different temperatures up to 1000 °C. Upon increasing the annealing temperature, from the X ray diffractogram the phase evolution Cu → Cu + Cu 2O → Cu 2O → Cu 2O + CuO → CuO was detected. Pure Cu 2O films are obtained at 200 °C, whereas uniform CuO films without structural surface defects such as terraces, kinks, porosity or cracks are obtained in the temperature range 300-550 °C. In both oxides, crystallization improves with annealing temperature. A resistivity phase diagram, which is obtained from the current-voltage response, is presented here. The resistivity was expected to increase linearly as a function of the annealing temperature due to evolution of oxides. However, anomalous decreases are observed at different temperatures ranges, this may be related to the improvement of the crystallization and crystallite size when the temperature increases. 相似文献
18.
This work reports on the effect of post-deposition rapid thermal annealing on the structural and electrical properties of deposited TiB 2 thin films. The TiB 2 thin films, thicknesses from 9 to 450 nm, were deposited by e-beam evaporation on high resistivity and thermally oxidized silicon wafers. The resistivity of as-deposited films varied from 1820 μΩ cm for the thinnest film to 267 μΩ cm for thicknesses greater than 100 nm. In the thickness range from 100 to 450 nm, the resistivity of TiB 2 films has a constant value of 267 μΩ cm. A rapid thermal annealing (RTA) technique has been used to reduce the resistivity of deposited films. During vacuum annealing at 7 × 10−3 Pa, the film resistivity decreases from 267 μΩ cm at 200 °C to 16 μΩ cm at 1200 °C. Heating cycles during RTA were a sequence of 10 s. According to scanning tunneling microscopy analysis, the decrease in resistivity may be attributed to a grain growth through polycrystalline recrystallization, as well as to an increase in film density. The grain size and mean surface roughness of annealed films increase with annealing temperature. At the same time, the conductivity of the annealed samples increases linearly with grain size. The obtained results show that RTA technique has a great potential for low resistivity TiB2 formation. 相似文献
19.
Er 3+-doped Y 2Ti 2O 7 and Er 2Ti 2O 7 thin films were fabricated by sol-gel spin-coating method. A well-defined pyrochlore phase Er xY 2-xTi 2O 7 was observed while the annealing temperature exceeded 800 °C. The average transmittance of the Er xY 2-xTi 2O 7 thin films annealed at 400 to 900 °C reduces from ∼ 87 to ∼ 77%. The refractive indices and optical band gaps of Er xY 2-xTi 2O 7 ( x = 0-2) annealed at 800 °C/1 h vary from 2.20 to 2.09 and 4.11 to 4.07 eV, respectively. The ∼ 1.53 μm photoluminescence spectrum of Er 3+ (5 mol%)-doped Y 2Ti 2O 7 thin films annealed at 700 °C/1 h exhibits the maximum intensity and full-width at half maximum (∼ 60 nm). 相似文献
20.
Pb 0.5Sr 0.5TiO 3 thin films were prepared on Pt/TiO 2/SiO 2/Si and LaNiO 3 (LNO)/Si substrates by using chemical solution deposition technique, and a layer-by-layer annealing method was used in an attempt to improve the dielectric properties of the thin films. The structure, dielectric, and ferroelectric properties of the thin films were investigated. Improved dielectric properties of the thin films were clearly confirmed: the dielectric constant and dielectric loss for the films on Pt/TiO 2/SiO 2/Si substrates annealed at 650 °C were 1064 and 0.027, respectively, at 1 kHz, with a dielectric tunability of more than 50%; similarly, the films prepared on LNO/Si substrates, showed a high dielectric constant of 1280 and a low dielectric loss of 0.023, at 1 kHz. P-E hysteresis loop measurements indicated that the remanent polarization and coercive field for the films on Pt/TiO 2/SiO 2/Si substrates annealed at 650 °C were 15.7 μC/cm 2 and 51 kV/cm, respectively. 相似文献
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