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1.
We report the formation of homogeneous and stable V2O3 nanocrystals, directly from V2O5 thin films, at 600 °C, as observed by using in situ electron microscopy experiments. Thermally-induced reduction of V2O5 thin films in vacuum is remarkably different when compared to reduction of V2O5 single crystals and results in the formation of nanophase V2O3. Thermally grown V2O3 nanocrystals exhibit hexagon or square shape and are stable at higher temperature as well as room temperature. The formation of stable nanocrystals through the reduction process in a non-chemical environment (vacuum) could provide a basis for understanding the complex processes of vanadium oxide phase transitions and for controlling the chemical processes to produce oxide nanocrystals. 相似文献
2.
Célia M. Ronconi Nathalia Suvorova Eugene A. Irene 《Journal of Physics and Chemistry of Solids》2009,70(1):234-557
Thin Cd2Nb2O7 films were grown on single-crystal p-type SiO2/Si substrates by the metallo-organic decomposition (MOD) technique. The films were investigated by X-ray diffraction, X-ray energy-dispersive spectroscopy, and field emission scanning electron microscopy, and showed a single phase (cubic pyrochlore), a crack-free spherical grain structure, and nanoparticles with a mean size of about 68 nm. A Cauchy model was also used in order to obtain the thickness and index of refraction of the stack layers (transparent layer/SiO2/Si) by spectroscopic ellipsometry (SE). The dielectric constant (K) of the films was calculated to be about 25 from the capacitance-voltage (C-V) measurements. 相似文献
3.
Y. Peña S. LugoM. Calixto-Rodriguez A. VázquezI. Gómez P. Elizondo 《Applied Surface Science》2011,257(6):2193-2196
In this work, we report the formation of CuInS2 thin films on glass substrates by heating chemically deposited multilayers of copper sulfide (CuS) and indium sulfide (In2S3) at 300 and 350 °C in nitrogen atmosphere at 10 Torr. CIS thin films were prepared by varying the CuS layer thickness in the multilayers with indium sulfide. The XRD analysis showed that the crystallographic structure of the CuInS2 (JCPDS 27-0159) is present on the deposited films. From the optical analysis it was estimated the band gap value for the CIS film (1.49 eV). The electrical conductivity varies from 3 × 10−8 to 3 Ω−1 cm−1 depending on the thickness of the CuS film. CIS films showed p-type conductivity. 相似文献
4.
Films of Bi2O3 were grown on glass substrate under atmospheric pressure by means of halide chemical vapour deposition (AP-HCVD) using BiI3 and O2 as the starting materials. In the XRD diffractogram of the film a strong diffraction peak appears at 27.91° assigned to the (111) diffraction of the δ-Bi2O3 with cubic structure. X-ray pole figure suggested that the 〈111〉 direction of the film is perpendicular to the substrate surface, while the 〈110〉 axis directs towards all directions parallel to the substrate surface. It is for the first that δ-Bi2O3 film was prepared on glass substrate. 相似文献
5.
Alaa A. Akl 《Applied Surface Science》2007,253(17):7094-7099
V2O5 thin films were prepared under various conditions by using reactive RF sputtering technique. The microstructure and electrical properties of the films are have been investigated. X-ray diffraction data revealed the films deposited at low O2/Ar ratio are amorphous. The orthorhombic structure of film improved after post annealing at 873 K. The microstructure parameters (crystallite/domain size and macrostrain) have been evaluated by using a single order Voigt profile method. Using the two-point probe technique, the dark conductivity as a function of the condition parameters such as film thickness, oxygen content and temperature are discussed. It was also found that, the behaviour of ρd versus d was found to fit properly with the Fuchs-Sondheimer relation with the parameters: ρo = 2.14 × 107 Ω cm and ?o = 112 ± 2 nm. At high temperature, the electrical conductivity is dominated by grain boundaries, the values of activation energy and potential barrier height were 0.90 ± 0.02 eV and 0.92 ± 0.02 V, respectively. 相似文献
6.
A. Benayad H. Martinez A. Gies B. Pecquenard A. Levasseur D. Gonbeau 《Journal of Electron Spectroscopy and Related Phenomena》2006
Vanadium pentoxide thin films, usable as positive electrode in microbatteries, have been prepared by radio frequency magnetron sputtering in a pure argon or mixed argon/oxygen plasma. Depending on the oxygen pressure in the discharge gas, we have obtained either crystallized or amorphous thin films. These two kinds of thin films having different electrochemical behavior, an extensive X-ray photoelectron spectroscopy (XPS) study (especially suited for thin films analysis) was carried out. The main redox processes occurring during the first discharge–charge cycle were identified. In addition, depending on the crystalline or amorphous character of the samples, we have noticed some differences concerning the kinetic of reduction. Furthermore, the growth of a surface layer between the cathode and the liquid electrolyte was evidenced upon the discharge as well as its partial dissolution upon the charge. 相似文献
7.
Ternary thin films of cerium titanium zirconium mixed oxide were prepared by the sol-gel process and deposited by a spin coating technique at different spin speeds (1000-4000 rpm). Ceric ammonium nitrate, Ce(NO3)6(NH4)2, titanium butoxide, Ti[O(CH2)3CH3]4, and zirconium propoxide, Zr(OCH2CH2CH3)4, were used as starting materials. Differential calorimetric analysis (DSC) and thermogravimetric analysis (TGA) were carried out on the CeO2-TiO2-ZrO2 gel to study the decomposition and phase transition of the gel. For molecular, structural, elemental, and morphological characterization of the films, Fourier Transform Infrared (FTIR) spectral analysis, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), cross-sectional scanning electron microscopy (SEM), and atomic force microscopy (AFM) were carried out. All the ternary oxide thin films were amorphous. The optical constants (refractive index, extinction coefficient, band gap) and thickness of the films were determined in the 350-1000 nm wavelength range by using an nkd spectrophotometer. The refractive index, extinction coefficient, and thickness of the films were changed by varying the spin speed. The oscillator and dispersion energies were obtained using the Wemple-DiDomenico dispersion relationship. The optical band gap is independent of the spin speed and has a value of about Eg≈2.82±0.04 eV for indirect transition. 相似文献
8.
K.M. Nissamudeen 《Journal of Physics and Chemistry of Solids》2009,70(5):821-325
Nanostructured europium-doped yttrium oxide thin films with lithium as a co-dopant were prepared using pulsed laser ablation technique. X-ray diffraction studies of the films indicated amorphous nature of the as deposited films and a transformation to crystalline phase with increase of annealing temperature. In this transformation, lithium co-doped films showed early crystallization. Lithium substitution resulted not only in enhancement of photoluminescence at 612 nm, resulting from 5D0-7F2 transition within europium, but also found to reduce the required processing temperature for intense photoemission. The deviation observed in the value of lattice constant of films annealed at different temperatures is found to be sensitive to annealing temperature. In the light of this, the dependence of photoluminescence intensity on the magnitude of lattice imperfection is also discussed. The morphology and transmittance of the films are also found to be sensitive to annealing process and lithium doping. 相似文献
9.
We apply density functional theory and the augmented spherical wave method to analyze the electronic structure of V2O3 in the vicinity of an interface to Al2O3. The interface is modeled by a heterostructure setup of alternating vanadate and aluminate slabs. We focus on the possible modifications of the V2O3 electronic states in this geometry, induced by the presence of the aluminate layers. In particular, we find that the tendency of the V 3d states to localize is enhanced and may even cause a metal-insulator transition. 相似文献
10.
J.H. Shy 《Journal of Physics and Chemistry of Solids》2005,66(11):2123-2126
CuAlO2 thin film was successfully prepared by rapid thermal annealing of an Al2O3/Cu2O/sapphire structure in air above 1000 °C. The film was mostly with single crystalline structure as verified by X-ray diffraction methods. We found that crystal quality and electrical conductivity of the films were affected by the cooling rate after annealing. The highest conductivity obtained in this work was 0.57 S/cm. Optical gap of this film was determined to be 3.75 eV. 相似文献
11.
Structure-related infrared optical properties of BaTiO3 thin films grown on Pt/Ti/SiO2/Si substrates
Z.G. Hu G.S. Wang Z.M. Huang J.H. Chu 《Journal of Physics and Chemistry of Solids》2003,64(12):2445-2450
BaTiO3 thin films with different thickness have been grown on Pt/Ti/SiO2/Si substrates by a modified sol-gel method. X-ray diffraction analyses show that the BaTiO3 thin films are polycrystalline. The crystalline quality of the films is improved with increasing thickness. The infrared optical properties of the BaTiO3 thin films have been investigated using an infrared spectroscopic ellipsometry in the wave number range of 800-4000 cm−1 (2.5-12.5 μm). By fitting the measured pseudodielectric functions with a three-phase model (Air/BaTiO3/Pt), and a derived classical dispersion relation for the thin films, the optical constants and thicknesses of the thin films have been simultaneously obtained. The refractive index of the BaTiO3 thin films increases and on the other hand, the extinction coefficient does not change with increasing thickness in the entirely measured wave number range. The dependence of the refractive index on the film thickness has been discussed in detail and was mainly due to both the crystalline quality of the films and packing density. Finally, the absorption coefficient was calculated in the infrared region for applications in the pyroelectric IR detectors. 相似文献
12.
Dielectric properties, viz. dielectric constant ε′, loss tan δ and a.c conductivity σac (over a wide range of frequency and temperature) and dielectric breakdown strength of PbO-Sb2O3-As2O3 glasses doped with V2O5 (ranging from 0 to 0.5 mol%) are studied. Analysis of these results, based on optical absorption and ESR spectra, indicates that the insulating strength of the glasses is comparatively high when the concentration of V2O5 is about 0.3 mol% in the glass matrix. 相似文献
13.
Preparation of Cu2ZnSnS4 thin films by hybrid sputtering 总被引:2,自引:0,他引:2
Tooru Tanaka Takeshi Nagatomo Mitsuhiro Nishio Akihiro Wakahara Hiroshi Ogawa 《Journal of Physics and Chemistry of Solids》2005,66(11):1978-1981
In order to fabricate Cu2ZnSnS4 thin films, hybrid sputtering system with two sputter sources and two effusion cells is used. The Cu2ZnSnS4 films are fabricated by the sequential deposition of metal elements and annealing in S flux, varying the substrate temperature. The Cu2ZnSnS4 films with stoichiometric composition are obtained at the substrate temperature up to 400 °C, whereas the film composition becomes quite Zn-pool at the substrate temperature above 450 °C. The Cu2ZnSnS4 film shows p-type conductivity, and the optical absorption coefficient and the band gap of the Cu2ZnSnS4 film prepared in this experiment are suitable for fabricating a thin film solar cell. 相似文献
14.
A.V. Kokate L.V. Gavali P.P. Hankare B.K. Chougule 《Journal of Physics and Chemistry of Solids》2006,67(11):2331-2336
Thin films of CdIn2S4 have been deposited on to stainless steel and fluorine-doped tin oxide (FTO)-coated glass substrates from aqueous acidic bath using an electrodeposition technique. Ethylene diamine tetra-acetic acid (EDTA) disodium salt is used as complexing agent to obtain good-quality deposits by controlling the rate of the reaction. The different preparative parameters like concentration of bath, deposition time, bath temperature, pH of the bath have been optimized by the photoelectrochemical (PEC) technique in order to get good-quality photosensitive material. Different techniques have been used to characterize CdIn2S4 thin films. Optical absorption shows the presence of direct transition with band gap energy 2.17 eV. The X-ray diffraction (XRD) analysis of the as-deposited and annealed films showed the presence of polycrystalline nature. Energy-dispersive analysis by X-ray (EDAX) study for the sample deposited at optimized preparative parameters shows that the In-to-Cd ratio is almost 2 and S-to-Cd ratio is almost 4. Scanning electron microscopy (SEM) for samples deposited at optimized preparative parameters reveals that spherical grains are uniformly distributed over the surface of the substrate indicates the well-defined growth of polycrystalline CdIn2S4 thin film. PEC characterization of the films is carried out by studying photoresponse, spectral response and photovoltaic output characteristics. The fill factor (ff) and power conversion efficiency (η) of the cell are 69 and 2.94%, respectively. 相似文献
15.
Y2O3:Eu3+ phosphor films have been developed by using the sol-gel process. Comprehensive characterization methods such as Photoluminescent (PL) spectroscopy, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy were used to characterize the Y2O3:Eu3+ phosphor films. In this experiment, the XRD profiles show that the Y2O3:Eu3+ phosphor films crystallization temperature and optimum annealing temperature occur at about 650 and 750 °C, respectively. The optimum dopant concentration is 12 mol% Eu3+ and the critical transfer distance (Rc) among Eu3+ ions is calculated to be about 0.84 nm. Vacuum environment is more efficient than oxygen and nitrogen to eliminate the OH content and hence yields higher luminescent phosphor films. The PL emission intensity of Y2O3:Eu3+ phosphor films is also dependent on the annealing time. It was found that the H2O impurities were effectively eliminated after annealing time of 25 s at 750 °C in vacuum environment. From the experiment results, the schematic energy band diagram of Y2O3:Eu3+ phosphor films is constructed. 相似文献
16.
Epitaxial (001)-oriented PbSc0.5Ta0.5O3 (PST) thin films were deposited by pulsed laser deposition. Local piezoelectric investigations performed by piezoelectric force microscopy show a dual slope for the piezoelectric coefficient. A piezoelectric coefficient of 3 pm/V was observed at voltages up to 0.8 V. However, at voltages above 0.8 V, there is a steep increase in piezoelectric coefficient mounting to 23.2 pm/V. This nonlinear piezoelectric response was observed to be irreversible in nature. In order to better understand this nonlinear behavior, voltage dependent dielectric constant measurements were performed. These confirmed that the piezoelectric non-linearity is indeed a manifestation of a dielectric non-linearity. In contrast to classical ferroelectric systems, the observed dielectric non-linearity in this relaxor material cannot be explained by the Rayleigh model. Thus the dielectric non-linearity in the PST films is tentatively explained as a manifestation of a percolation of the polar nano regions. 相似文献
17.
Investigations were realized on the microstructural and morphological evolution of RF-sputtered vanadium pentoxide thin films during growth. V2O5 thin films at different stages of growth were studied by spectroscopic ellipsometry, X-ray diffraction, atomic force microscopy and scanning electron microscopy. Film grain orientation, roughness and density were found to have notable evolution during growth. Electrochemical tests in liquid and solid electrolyte state configuration showed non-linear relationship between discharge capacity and V2O5 film thickness (<1 μm), which could be attributed in parts to the observed morphological and microstructural changes during growth, mainly the existence of a gradient density through film thickness and the pronounced top surface roughness. 相似文献
18.
Y. Akaki S. Kurihara K. Tsurugida T. Kakeno 《Journal of Physics and Chemistry of Solids》2005,66(11):1858-1861
Structural electrical and optical properties of AgInS2 (AIS) thin films grown by the single-source thermal evaporation method were studied. The X-ray diffraction spectra indicated that the AIS single phase was successful grown by annealing above 400 °C in air. The AIS grain sizes became large with increasing the annealing temperatures. All polycrystalline AIS thin films were sulfur-poor from the electron probe microanalysis and indicated n-type conduction by the Van der Pauw technique. It was deduced that the sulfur vacancies were dominant in the films and enhanced n-type conduction. 相似文献
19.
Shigeyuki Nakamura Shizutoshi Ando 《Journal of Physics and Chemistry of Solids》2005,66(11):1944-1946
Metal-organic decomposition (MOD) technique has been developed as a low cost thin film CuInS2 preparation method for solar cell application. XRD and Raman spectra measurement revealed that deposited films contain CuInS2. Stoichiometric films with a bandgap of 1.53 eV and an FWHM of 0.45° were obtained from a solution with Cu/In=1.5. 相似文献
20.
A.P ToraneC.H Bhosale 《Journal of Physics and Chemistry of Solids》2002,63(10):1849-1855
Semiconducting Sb2Se3 thin films have been prepared onto the stainless steel and fluorine doped tin oxide coated glass substrates from non-aqueous media using an electrodeposition technique. The electrodeposition potentials for different bath compositions and concentrations of solution have been estimated from the polarization curves. SbCl3 and SeO2 in the volumetric proportion as 1:1 with their equimolar solution concentration of 0.05 M form good quality films. The films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical absorption techniques. The SEM studies show that the film covers the total substrate surface with uneven surface morphology. The XRD patterns of the films obtained by varying compositions and concentrations show that the as-deposited films are polycrystalline with relatively higher grain size for 1:1 composition and 0.05 M concentration. The optical band gap energy for indirect transition in Sb2Se3 thin films is found to be 1.195 eV. 相似文献