共查询到20条相似文献,搜索用时 8 毫秒
1.
R. Kurt W. Pitschke A. Heinrich J. Schumann J. Thomas K. Wetzig A. Burkov 《Thin solid films》1997,310(1-2):8-18
Experimental data on the phase formation process of amorphous IrxSi1−x thin films with 0.30 ≤ x ≤ 0.41 are presented and discussed in relation to electric transport properties. The structure formation process at temperatures from 300 K up to 1223 K was investigated by means of X-ray diffraction. Distinct phases were observed in the final stage in dependence on the initial composition: Ir3Si4, Ir3Si5, and IrSi3. An unknown metastable phase was found in films with a silicon concentration of 61 at.% to 64 at.% after annealing above the crystallization temperature T = 970 K. The crystal structure of this phase was determined by the combined use of X-ray diffraction and electron diffraction. It was found to be monoclinic, basic-face centred with lattice constants a = 1.027 nm, b = 0.796 nm, c = 0.609 nm, and γ = 113.7°. Additionally, microstructure and morphology of the films were investigated by transmission electron microscopy (TEM). The annealing process was studied by means of mechanical stress investigations as well as by electrical resistivity and thermopower measurements. Correlations between the structure, the phase formation and the electrical transport behaviour are discussed on the basis of conduction mechanism. 相似文献
2.
Thin (t−0.60 μm) films of ZnSexCdS1−x were formed by vacuum evaporation on glass substrates held at 350 and 470 K. XRD studies showed that all the films were polycrystalline in nature. Films with x0.70 were hexagonal whereas films with x0.80 were cubic in structure. The structural transition was in the range 0.70<x<0.80. The lattice parameter was higher in films formed at a higher temperature. The lattice parameter followed Vegard's law. Grain size increased with substrate temperature. From the optical transmission spectra recorded in the wavelength range 300–2500 nm, the extinction coefficient, refractive index and band gaps were obtained. Band gap values showed a downward bowing with ‘x' with a bowing parameter of 0.40 eV. 相似文献
3.
F. Smaïli M. Kanzari B. Rezig 《Materials science & engineering. C, Materials for biological applications》2008,28(5-6):954-958
Ingots containing single crystals of the quaternary alloys CuIn1 − xAlxS2 (CIAS) were grown by a horizontal Bridgman method for compositions with x = 0, 0.2 and x = 0.4. (CIAS) thin films were prepared by thermal evaporation technique on to glass substrates. Structural and optical properties of the films were studied in function of the Al content. Band gap, and absorption coefficients were determined from the analysis of the optical spectra (transmittance and reflectance as a function of wavelength) recorded by a spectrophotometer. The samples have direct bandgap energies of 1.95 eV (x = 0), 2.06 eV (x = 0,2) and 2.1 eV (x = 0,4). These optical results were correlated with the structural analysis by X-Ray diffraction. 相似文献
4.
Rong Wu Piyi Du Wenjian Weng Gaorong Han 《Materials Science and Engineering: B》2006,130(1-3):282-287
The BaxSr1−xTiO3 (BST)/Pb1−xLaxTiO3 (PLT) composite thick films (20 μm) with 12 mol% amount of xPbO–(1 − x)B2O3 glass additives (x = 0.2, 0.35, 0.5, 0.65 and 0.8) have been prepared by screen-printing the paste onto the alumina substrates with silver bottom electrode. X-ray diffraction (XRD), scanning electron microscope (SEM) and an impedance analyzer and an electrometer were used to analyze the phase structures, morphologies and dielectric and pyroelectric properties of the composite thick films, respectively. The wetting and infiltration of the liquid phase on the particles results in the densification of the composite thick films sintered at 750 °C. Nice porous structure formed in the composite thick films with xPbO–(1 − x)B2O3 glass as the PbO content (x) is 0.5 ≥ x ≥ 0.35, while dense structure formed in these thick films as the PbO content (x) is 0.8 ≥ x ≥ 0.65. The volatilization of the PbO in PLT and the interdiffusion between the PLT and the glass lead to the reduction of the c-axis of the PLT phase. The operating temperature range of our composite thick films is 0–200 °C. At room temperature (20 °C), the BST/PLT composite thick films with 0.35PbO–0.65B2O3 glass additives provided low heat capacity and good pyroelectric figure-of-merit because of their porous structure. The pyroelectric coefficient and figure-of-merit FD are 364 μC/(m2 K) and 14.3 μPa−1/2, respectively. These good pyroelectric properties as well as being able to produce low-cost devices make this kind of thick films a promising candidate for high-performance pyroelectric applications. 相似文献
5.
Tran Thi Lan Anh Young Eon Ihm Dojin Kim Hyojin Kim Chang Soo Kim Sang Soo Yu 《Thin solid films》2009,518(1):309-312
We have studied the electrical and magnetic properties of p-type semiconductor thin films of Si1 − xMnx/Si (x = 0.036 and 0.05) grown by molecular beam epitaxy. Experimental results reveal that the resistivity of the samples decreases gradually with increasing measurement temperature, which can be described well by Mott's variable-range-hopping model. All the samples exhibit the ferromagnetic ordering above room temperature. Among these samples, Si0.95Mn0.05 has a higher hole density and magnetization. This indicates an enhancement of hole-mediated ferromagnetic exchange interactions when the Mn-doping concentration is increased. 相似文献
6.
A. Bonakdarpour K. C. Hewitt T. D. Hatchard M. D. Fleischauer J. R. Dahn 《Thin solid films》2003,440(1-2):11-18
Thin films of Mo1−xSnx, continuously and linearly mapped for 0<x<1, have been prepared by d.c. magnetron sputter deposition under various growth conditions. X-ray diffraction results indicate that as x in high-pressure deposited Mo1−xSnx increases from 0 to approximately 0.45, the bcc lattice expands and no new phases are formed. At low deposition pressures, Mo3Sn, a β-tungsten structured phase, is formed along with the bcc Mo–Sn solid solution for 0.1<x<0.3. The variation of the lattice parameter for this intermetallic phase also indicates that solid solutions, possibly of the form Mo3+ySn, are being formed. These materials are of special interest as anode candidates in lithium-ion batteries. 相似文献
7.
Thin films of Ge28−xSe72Sbx (x=0, 8, 16, 24 at%) with thickness of 200 nm are prepared by thermal evaporation onto glass substrates under vacuum of 5.3×10−5 mbar. Optical reflectance and transmittance of these films are measured at room temperature in the light wavelength region from 200 to 1100 nm. The estimated optical energy gap, Eg, is found to decrease from 2 eV (0 at% Sb) to 1.5 eV (24 at% Sb), whereas the band tail width, Ee, increases from 0.062 to 0.077 eV, respectively. The refractive index, n, and extinction coefficient, κ, are determined as functions of wavelength. The DC electrical conductivity, σ, of films is measured as a function of temperature in the range from 300 to 360 K. The extracted value of activation energy, ΔE, is found to decrease from 0.95 eV (0 at% Sb) to 0.74 eV (24 at% Sb). Optical and electrical behavior of films can be explained in terms of cohesive energy (CE) and Se-Se defect bonds. 相似文献
8.
Copper indium disulphide (CuInS2) is an absorber material for solar cell and photovoltaic applications. By suitably doping CuInS2 thin films with dopants such as Zn, Cd, Na, Bi, Sn, N, P and As its structural, optical, photoluminescence properties and electrical conductivities could be controlled and modified. In this work, Sb (0.01 mole (M)) doped CuInS2 thin films are grown in the temperature range 300-400 °C on heated glass substrates. It is observed that the film growth temperature, the ion ratio (Cu/In = 1.25) and Sb-doping affects the structural, optical and photoluminescence properties of sprayed CuInS2 films.The XRD patterns confirm that the Sb-doping suppresses the growth of CuInS2 polycrystalline thin films along (1 1 2) preferred plane and in other characteristic planes. The EDAX results confirm the presence of Cu, In, S and Sb. About 60% of light transmission occurs in the wavelength range 350-1100 nm. The absorption coefficient (α) is found to be in the order of 105 cm−1. The band gap energy increases as the temperature increases from 300-400 °C (1.35-1.40 eV). SEM photographs depict that large sized crystals of Sb-doped CuInS2 (1 μm) are formed on the surface of the films. Well defined sharp blue and green band emissions are exhibited by Sb-doped CuInS2 thin films. Defects-related photoluminescence emissions are discussed. These Sb-doped CuInS2 thin films are prepared by the cost effective method of spray pyrolysis from the aqueous solutions of CuCl2, InCl3, SC(NH2)2 and SbCl3 on heated glass substrates. 相似文献
9.
An electrode/electrolyte interface has been formed between an n-type CdSe1−xTex (0≤x≤1) alloyed/mixed type semiconductor and a sulphide/polysulphide redox electrolyte. It has been investigated through the current–voltage, capacitance–voltage and spectrally selective properties. The dependence of the dark current through the junction and the junction capacitance on the voltage across the junction have been examined and analysed. It appeared that the current transport mechanism across the junction is strongly influenced by the recombination mechanism at the interface and series resistance effects. Upon illumination of the interface with a light of 20 mW cm−2, an open circuit voltage of the order of 0.35 V and a short circuit current of 212 μA cm−2 have been developed (for x=0.2), yielding an efficiency of energy conversion equal to 0.2% and a form factor of 45%. The action spectra in the 450–1000 nm wavelength range showed presence of the interface states at the electrode/electrolyte interface. The magnitudes of the barrier heights at the interfaces were also determined. It has been seen that a significant improvement in the electrochemical performance of a cell is noticed for the electrode composition with x=0.2. 相似文献
10.
Influence of spray pyrolysis deposition parameters on the optoelectronic properties of WO3 thin films 总被引:1,自引:0,他引:1
The electrochromic (EC) properties of tungsten oxide (WO3), such as coloration efficiency, cyclic durability and reversibility strongly depend on the structural and morphological properties, which are influenced by the deposition method and parameters.This paper presents the steps for optimizing the deposition parameters (substrate temperature, air flow pressure and precursor solution molarity) for improving the optical and electrical properties of WO3 thin films for EC applications. WO3 thin films were deposited by spray pyrolysis using tungsten hexachloride (WCl6) dissolved in ethanol as precursor solution. The EC properties of optimized films were tested in two different electrolytes (H2SO4 1 M and acetic acid/sodium acetate buffer with pH = 4) and changes in structure, composition and morphology of the films after coloration/bleaching cycles were discussed.The deposition temperature, carrier gas pressure and solution molarity were optimized at 250 °C, 120 kPa and 0.14 M respectively. Under these condition a dense, uniform film, with homogenous distribution of particles, good adhesion to the substrate, low roughness (9.02 nm), high transparency (> 70% in the 500-1100 nm range) and conductivity was obtained. Transmission modulation is higher for the sample cycled in H2SO4 1 M (64% at 630 nm) compared to that cycled in the buffer (21% at 630 nm), whereas opposite results were obtained for coloration efficiencies 28 cm2 C− 1 (at 630 nm) and 35 cm2 C− 1 (at 630 nm), respectively. Changes in surface chemistry and morphology of the optimized sample were observed after cycling in H2SO4. 相似文献
11.
Optical constants of vacuum-evaporated thin films in the Ge1 − xSe2Pbx (x = 0, 0.2, 0.4, 0.6) system were calculated from reflectance and transmittance spectra. It is found that the films exhibit a non-direct gap, which decreases with increasing Pb content. The variation in the refractive index and the imaginary part of the dielectric constant with photon energy is reported. The relationship between the optical gap and chemical composition in chalcogenide glasses is discussed in terms of the average heat of atomization. 相似文献
12.
J.M. Peza-Tapia V.M. Snchez-Resndiz M.L. Albor-Aguilera J.J. Cayente-Romero L.R. De Len-Gutirrez M. Ortega-Lpez 《Thin solid films》2005,490(2):142-145
The structural, electrical and optical properties of Na-doped CuInS2 thin films grown by spray pyrolysis were studied. These films crystallized in the sphalerite structure of CuInS2, and showed to contain traces of indium sulfide and CuIn5S8 as impurity phases. All films were In-rich and showed p-type conductivity. The film conductivity was strongly affected by Na-doping, which decreased from 10−2 to 10−5 S/cm by increasing the [Na]/[Cu] ratio from 0.005 to 0.03 in the spray solution. The band gap energy was observed to increase, from 1.4 to 1.45 eV, with increasing the [Na]/[Cu] ratio. Our results suggested that Na could be an effective acceptor impurity in sprayed CuInS2. 相似文献
13.
In this paper, the effect of S and Al concentrations on the structural, electrical, optical, thermoelectric and photoconductive properties of the films was studied. The [Al]/[Sn] and [S]/[Sn] atomic ratios in the spray solutions were varied from 10 at.% to 40 at.% and 0 to 50 at.%, respectively. X-ray diffraction analysis showed the formation of SnO2 cassiterite phase as a main phase and the numerous sulfur phases including S, SnS, SnS2 and Sn2S3 in SnO2:Al films. Scanning electron microscopy studies showed that in the absence of S, increasing the Al content results in a smaller grain size and with the addition of S, the films appear to contain small cracks and nodules. The minimum resistance of 0.175 (kΩ/□) was obtained for S-doped SnO2:Al (40 at.%) film with 20 at.% S-doping. From the Hall effect measurements, the majority carrier concentration was obtained in order of 1017-1018 cm− 3. The thermoelectric measurements showed that majority carriers change from electrons to holes for S-doping in SnO2:Al (40 at.%) thin films. The maximum Seebeck coefficient of + 774 μV/K (at T = 370 K) was obtained for S-doped SnO2:Al (10 at.%) film with 50 at.% S-doping. The band gap values were obtained in the range of 3.8-4.2 eV. The S-doped SnO2:Al (40 at.%) films have shown considerably photoconductivity more than S-doped SnO2:Al (10 at.%) with increasing S-doping. The best photoconductive property was obtained for co-doped SnO2 thin film with 40 at.% Al and 5 at.% S concentration in solution. 相似文献
14.
D. Besson M. Treilleux A. Hoareau C. Esnouf 《Materials Science and Engineering: B》2002,90(3):213-223
We present a new gas-aggregation cluster source with two independent crucibles, one for indium and another one for antimony. This source was used to produce mixed InxSb1−x clusters in the nanometer range size (typically 4 nm), which were deposited at room temperature on amorphous carbon or glass substrates by low energy cluster beam deposition technique (LECBD). The film composition was analysed by energy dispersive X-ray (EDX) spectroscopy. The morphology and structure of the films were studied by transmission electron microscopy (conventional and high resolution) and selected area electron diffraction (SAED) at different compositions. Semiconducting InSb clusters could be produced by controlling the temperature of the two crucibles. The electrical properties of the films were studied at a film thickness of 20 nm. The conductivity versus temperature appeared to be thermally activated for all compositions. 相似文献
15.
P-type transparent conducting CuAlO2 thin films were prepared by e-beam evaporation and wet-oxidation technique. CuAlO2 film was preferentially (006) oriented after wet-oxidation. The transmittance varied from 20 to 85% and the resistivity varied from 5 × 10− 3 to 4 Ω cm with wet-oxidation conditions. The nature of p-type films was confirmed by the positive hall coefficient. Optical band gap was estimated to be in the range of 3.96-4.20 eV. These behaviors were due to the decrease of oxygen deficient state in the film as oxidation progresses. Microstructural observations of films showed smooth morphology with 23.2-29.7 Å rms roughness. 相似文献
16.
Optical properties of In2O3 films prepared by spray pyrolysis 总被引:1,自引:0,他引:1
P. Prathap Y.P.V. Subbaiah M. Devika K.T. Ramakrishna Reddy 《Materials Chemistry and Physics》2006,100(2-3):375-379
In2O3 thin films have been deposited on glass substrates by spray pyrolysis. InCl4 was used as the solute to prepare the starting solution with a concentration of 0.1 M. The films were grown at different substrate temperatures ranging from 300 to 400 °C. The as-grown layers were optically characterized in order to evaluate the absorption coefficient, optical band gap, refractive index, extinction coefficient and other optical parameters. The influence of substrate temperature on these parameters was reported and discussed. 相似文献
17.
The photovoltaic Cd1−xZnxS thin films, fabricated by chemical bath deposition, were successfully used as n-type buffer layer in CuInGaSe2 (CIGS) solar cells. Comprehensive optical properties of the Cd1−xZnxS thin films were measured and modeled by spectroscopic ellipsometry (SE), which is proven to be an excellent and non-destructive technique to determine optical properties of thin films. The optical band gap of Cd1−xZnxS thin films can be tuned from 2.43 eV to 3.25 eV by controlling the Zn content (x) and deposition conditions. The wider-band-gap Cd1−xZnxS film was found to be favorable to improve the quantum efficiency in the wavelength range of 450-550 nm, resulting in an increase of short-circuits current for solar cells. From the characterization of quantum efficiency (QE) and current-voltage curve (J-V) of CIGS cells, the Cd1−xZnxS films (x = 0.32, 0.45) were demonstrated to significantly enhance the photovoltaic performance of CIGS solar cell. The highest efficiency (10.5%) of CIGS solar cell was obtained using a dense and homogenous Cd0.68Zn0.32S thin film as the buffer layer. 相似文献
18.
Amorphous thin films of glassy alloys of Se75S25 − xCdx (x = 2, 4 and 6) were prepared by thermal evaporation onto chemically cleaned glass substrates. Optical absorption and reflection measurements were carried out on as-deposited and laser-irradiated thin films in the wavelength region of 500-1000 nm. Analysis of the optical absorption data shows that the rule of no-direct transitions predominates. The laser-irradiated Se75S25 − xCdx films showed an increase in the optical band gap and absorption coefficient with increasing the time of laser-irradiation. The results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The value of refractive index increases decreases with increasing photon energy and also by increasing the time of laser-irradiation. With the large absorption coefficient and change in the optical band gap and refractive index by the influence of laser-irradiation, these materials may be suitable for optical disc application. 相似文献
19.
Thin films were thermally evaporated from the bulk glasses of As40Se60 − xSbx (with x = 0, 5, 10, 15 at.%) under high vacuum. We have characterized the deposited films by Fourier Transform Infrared spectroscopy. The relationship between the structural and optical properties and the compositional variation has been investigated. Increasing Sb content was found to affect the thermal and optical properties of these films. Non-direct electronic transition was found to be responsible for the photon absorption inside the investigated films. It was found that, the optical band gap Eo decreases while the width of localized states (Urbach energy) Ee increases. 相似文献
20.
Copper indium disulphide, CuInS2, is a promising absorber material for thin film photovoltaic which has recently attracted considerable attention due to its suitability to reach high efficiency solar cells by using low-cost techniques. In this work CuInS2 thin films have been deposited by chemical spray pyrolysis onto glass substrates at ambient atmosphere, using different composition solutions at various substrate temperatures. Structural, chemical composition and optical properties of CIS films were analysed by X-ray diffraction, energy dispersive X-ray spectroscopy and optical spectroscopy. Sprayed CIS films are polycrystalline with a chalcopyrite structure with a preferential orientation along the <112> direction and no remains of oxides were found after spraying in suitable conditions. X-ray microanalysis shows that a chemical composition near to stochiometry can be obtained. An optical gap of about 1.51 eV was found for sprayed CIS thin films. 相似文献