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1.
The ferroelectric thin films of Fe-doped BaTiO3 and undoped BaTiO3 were prepared on LaNiO3 coating Si substrates by sol–gel technique. It was found that a small amount of Fe dopant could significantly enhance the ferroelectric properties of the BaTiO3 thin film. The remnant polarization of Fe-doped BaTiO3 thin film at room temperature reached to 14.9 μC/cm2. The loss tangent, compared to the undoped BaTiO3 film, was increased with frequency increasing and the dielectric constant was decreased. The possible mechanism of enhanced ferroelectric properties of Fe-doped BaTiO3 thin film was discussed. The results show the potential role of Fe dopant in improving the ferroelectric properties of BaTiO3 thin film. 相似文献
2.
TiO2 thin films were deposited on polycarbonate (PC) substrate by ion beam assisted evaporation. The grain size increased with the ion anode voltage and film thickness. The TiO2 thin films had an amorphous structure. Moiré deflectometry was used to measure the nonlinear refractive indices of TiO2 thin films on PC substrates. The nonlinear refractive index was measured to be of the order of 10− 8 cm2 W− 1 and a change in refractive index was of the order of 10− 5. Dense TiO2 films exhibited high linear refractive indices, red-shift of the optical absorbance, and absorbance in the near-IR region. 相似文献
3.
Tomoki Narita Tamio Iida Kouichi Mizuno Akihiro Kondo Takashi Itoh Yasuhito Tanaka 《Thin solid films》2008,516(5):810-813
The effects of nitrogen ion bombardment on TiO2 films prepared by the Cat-CVD method have been studied to improve the optical and electrical properties of the material for use in Si thin film solar cells. The refractive index n and the dark conductivity of the TiO2 film increased with irradiation time. The refractive index n of the TiO2 film was changed from 2.1 to 2.4 and the electrical conductivity was improved from 3.4 × 10− 2 to 1.2 × 10− 1 S/cm by the irradiation. These results are due to the formation of Ti-N bonds and oxygen vacancies in the film. 相似文献
4.
Optical and electrical properties of multiferroic bismuth ferrite thin films fabricated by sol-gel technique 总被引:2,自引:0,他引:2
Single-phase multiferroic BiFeO3 thin films have been prepared on LaNiO3/Si(100) and Si(100) wafer via sol-gel technique. The films are polycrystalline with preferring orientation of (101). The film has a conspicuous absorption in the blue and green light region, and band gap of 2.74 eV. The refractive index and the extinction coefficient of the film is about 2.36 and 0.06 at 600 nm, 2.26 and close to zero in the range of 800-1200 nm, respectively. The films also exhibit favorable ferroelectric and dielectric properties. A large photo induced open-circuit voltage was observed, indicating that the film exhibits photovoltaic behaviours. 相似文献
5.
A. Hallbauer D. Huber G.N. Strauss S. Schlichtherle A. Kunz H.K. Pulker 《Thin solid films》2008,516(14):4587-4592
Thin films of Ta2O5, Nb2O5, and HfO2 were deposited by reactive-low-voltage-ion-plating (RLVIP) on unheated glass and silicon substrates. The film thickness was about 200 nm. Optical properties as well as mechanical film stress of these layers were investigated in dependence of various deposition parameters, i.e. arc current and oxygen partial pressure. For an arc current in the range between 40 and 50 A and an oxygen partial pressure of at least 11 · 10− 4 mbar good results were obtained. The refractive index and film thickness were calculated from spectrophotometric transmission data using the Swanepoel theory. For example at 550 nm wavelength the refractive index for thin RLVIP-Nb2O5-films was found to be n550 = 2.40. The optical absorption was obtained by photo-thermal deflection spectrometry. For the investigated materials absorption coefficients in the range of k = 5 · 10− 4 at 515 nm wavelength were measured. The mechanical film stress was determined by measuring the difference in bending of silicon substrates before and after the deposition process. For dense films, i.e. no water vapour sorption on atmosphere, the mechanical film stress was always compressive with values of some hundred MPa. In case of films deposited with higher arc currents (Iarc > 60A) and lower oxygen pressure (< 15 · 10− 4 mbar) the influence of a post deposition heat treatment at 350 °C for 4 h on air was also investigated. For these films the properties could clearly be improved by such treatment. However, by using lower arc currents and higher oxygen partial pressure during the ion plating process, immediately dense and environmental stable films with good optical as well as mechanical properties could be achieved without post deposition heat treatment. All the results obtained will be presented in graphs and diagrams. 相似文献
6.
Single phase Bi1.95La1.05TiNbO9 (LBTN-1.05) thin films with a layered aurivillius structure have been fabricated on fused silica substrates by pulsed laser deposition at 700 °C. The X-ray diffraction pattern revealed that the films are single-phase aurivillius. The band gap, linear refractive index and linear absorption coefficient were obtained by optical transmittance measurements. The film exhibits a high transmittance (> 70%) in visible-infrared region and the dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The nonlinear optical absorption property of the film was determined by the single beam Z-scan method using 800 nm with a duration of 100 fs. A large positive nonlinear absorption coefficient β = 5.95 × 10− 8 m/W was determined experimentally. The results showed that the LBTN-1.05 is a promising material for applications in absorbing-type optical devices. 相似文献
7.
Optical properties of thin chalcogenide films from the systems As-S(Se) and As-S-Se were investigated as a function of the film composition, film thickness and conditions of illumination by light using multiple-angle-of-incidence ellipsometry. Thin films were deposited by thermal evaporation and exposed to white light (halogen lamp) and to monochromatic light from Ar+ — (λ = 488, 514 nm) and He-Ne- (λ = 632.8 nm) lasers. The ellipsometric measurements were carried out at three different angles of light incidence in the interval 45-55°, at λ = 632.8 nm. An isotropic absorbing layer model was applied for calculation of the optical constants (refractive index, n and extinction coefficient, k) and film thickness, d. The homogeneity of the films was checked and verified by applying single-angle calculations at different angles. It was shown that the refractive index, n of As-S-Se films is independent of film thickness in the range of 50 to 1000 nm and its values varied from 2.45 to 3.05 for thin layers with composition As2S3 and As2Se3, respectively. The effect of increasing in the refractive index was observed after exposure to light which is related to the process of photodarkening in arsenic containing layers. The viability of the method for determining the optical constants of very thin chalcogenide films with a high accuracy was confirmed. 相似文献
8.
R.K. Kotnala Jyoti ShahMohan C. Mathpal K.C. VermaSandeep Singh Lovkush 《Thin solid films》2011,519(18):6135-6139
Humidity response of Radio Frequency sputtered MgFe2O4 thin films onto alumina substrate, annealed at 400 °C, 600 °C and 800 °C has been investigated. Crystalline phase formation of thin films annealed at different temperature was analyzed by X-ray Diffraction. A particle/grain like microstructure in the grown thin films was observed by Scanning Electron Microscope and Atomic Force Microscope images. Film thickness for different samples was measured in the range 820-830 nm by stylus profiler. Log R (Ω) response measurement was taken for all thin films for 10-90% relative humidity (% RH) change at 25 °C. Resistance of the film increased from 5.9 × 1010 to 3 × 1012 at 10% RH with increase in annealing temperature from 400 °C to 800 °C. A three-order magnitude, 1012 Ω to 109 Ω drop in resistance was observed for the change of 10 to 90% RH for 800 °C annealed thin film. A good linear humidity response, negligible humidity hysteresis and minimum response/recovery time of 4 s/6 s have been measured for 800 °C annealed thin film. 相似文献
9.
Lead-free piezoelectric thin films of NaNbO3-BaTiO3 were fabricated on Pt/TiOx/SiO2/Si substrates by chemical solution deposition. Perovskite NaNbO3-BaTiO3 single-phase thin films with improved leakage-current and ferroelectric properties were prepared at 650 °C by doping with a small amount of Mn. The 1.0 and 3.0 mol% Mn-doped 0.95NaNbO3-0.05BaTiO3 thin films showed slim ferroelectric P-E hysteresis and field-induced strain loops at room temperature. The 1.0 and 3.0 mol% Mn-doped 0.95NaNbO3-0.05BaTiO3 films showed remanent polarization values of 6.3 and 6.2 μC/cm2, and coercive field of 41 and 55 kV/cm, respectively. From the slope of the field-induced strain loop, the effective piezoelectric coefficient (d33) was found to be 40-60 pm/V. 相似文献
10.
Ba(Ti1 − x,Nix)O3 ferroelectric thin films with perovskite structure are prepared on fused quartz substrates by a sol-gel process. Optical transmittance measurements indicate that Ni-doping has an obvious effect on the energy band structure of BaTiO3. It has been found that the refractive index n, extinction coefficient k, and band gap energy Eg of the films are functions of the film composition. The Eg of Ba(Ti1 − x,Nix)O3 decreases approximately linearly as the Ni content increases, which is attributed to the decline of conduction band energy level with increasing the Ni content. On the other hand, n and k both increase linearly with increasing the Ni content because of the increase of packing density. These results indicate that thin films might have potential applications in BaTiO3-based thin-film optical devices. 相似文献
11.
Influence of both calcination ambient and film thickness on the optical and structural properties of sol-gel derived TiO2 thin films have been studied. X-ray diffraction results show that prepared films are in an anatase form of TiO2. Films calcined in argon or in low vacuum (∼2 × 10−1 mbar) are found to be smaller in crystallite size, more transparent at low wavelength region of ∼300-450 nm, denser, have higher refractive index and band gap energy compared to air-calcined films. Scanning electron microscopic study reveals that surfaces of TiO2 films calcined in argon or in low vacuum are formed by densely packed nano-sized particulates. Presence of voids and signs of agglomeration can be seen clearly in the surface microstructure of air-calcined films. In the thickness range ∼200-300 nm, band gap energy and crystallite size of TiO2 films remain practically unaffected with film thickness but refractive index of thinner film is found to be marginally higher than that of thicker film. In this work, it has been shown that apart from temperature and soaking time, partial pressure of oxygen of the ambient is also an important parameter by which crystallite size, microstructure and optical properties of the TiO2 films may be tailored during calcination period. 相似文献
12.
Nanocrystalline bismuth oxide thin films have been deposited by thermal oxidation, in air, of vacuum evaporated chopped bismuth thin films. The optical properties and adhesion have been studied. The oxidation temperature and duration were varied. As revealed by structural investigations, polycrystalline and multiphase bismuth oxide thin films were obtained. At all oxidation temperatures, monoclinic Bi2O3 is predominant. The films showed high transmittance in the visible range of spectrum. The direct band gap of the films obtained was between 2.78 eV and 3.04 eV. The refractive index observed is in the range 1.934 to 2.096. The adhesion of films was in the range 215 × 102 to 470 × 102 kgF/cm2. The values are strongly influenced by the heat treatment characteristics. It was observed that chopping helps in improving the adhesion and increasing refractive index, packing density and band gap of bismuth oxide thin films. These bismuth oxide films can have potential use in optical waveguides. 相似文献
13.
Microstructural properties are found to be variant in the BaTiO3 − x films grown on SrTiO3(001) substrate under various oxygen pressures from 2 × 10− 2 Pa to 2 × 10− 5 Pa by laser molecular-beam epitaxy. Transmission electron microscopic studies reveal that the predominant defects in the films change from threading dislocations into (111) planar defects (i.e. stacking faults and nanotwins) by lowering the oxygen pressure. High density of these defects was observed in the BaTiO3 − x film prepared at the oxygen pressure of 2 × 10− 5 Pa, which shows metallic behavior. The relationships between oxygen pressure, microstructure, and electrical properties are established on the basis of oxygen deficiency. The formation of nanotwins in highly oxygen-deficient BaTiO3 − x epitaxial thin films results from accommodating excess oxygen vacancies induced by lowering oxygen pressure. 相似文献
14.
This study investigates the optical and structural properties of SiOx (x ∼ 1) films prepared by an ion-assisted deposition (IAD) process. The films were prepared by evaporating silicon monoxide, with and without simultaneous Ar+ bombardment. The stoichiometry of each film was determined as measured by the infrared spectrometry and X-ray photoelectron spectrometry. The variation in the stoichiometry revealed that the oxygen content of the SiOx thin films varied slightly under the different conditions of the Ar+ bombardment. The results of the X-ray diffraction and transmission electron microscopy (TEM) measurements illustrated that all of the films had amorphous structures. However, a different interfacial appearance between the film and the substrate was observed from the TEM image. The optical constants of the SiOx thin films were determined by a spectroscopic ellipsometry. The extinction coefficient of all of the films approached zero in the infrared wavelength range from 2 to 7 μm, but the refractive index was varied by the IAD process. The variation of these refractive indices is mainly related to the packing density of the films. 相似文献
15.
Nickel diffusion in CuInSe2 thin films was studied in the temperature range 430-520 °C. Thin films of copper indium diselenide (CuInSe2) were prepared by selenization of CuInSe2-Cu-In multilayered structure on glass substrate. A thin film of Nickel was deposited and annealed at different temperatures. Surface morphologies of the Ni diffused and undiffused CuInSe2 films were investigated using scanning electron microscope. The alteration of Nickel concentration in the CuInSe2 thin film was measured by Energy Dispersive X-Ray Fluorescence (EDXRF) technique. These measurements were fitted to a complementary error function solution and the diffusion coefficients at four different temperatures were evaluated. The diffusion coefficients of Ni in CuInSe2 films were estimated from concentration profiles at temperatures 430-520 °C as D = 1.86 × 10− 7(cm2s− 1)exp[− 0.68(eV)/kT]. 相似文献
16.
X.W. WangX. Wang W.J. GongY.Q. Zhang Y.L. ZhuZ.J. Wang Z.D. Zhang 《Thin solid films》2012,520(7):2785-2788
BaTiO3 films were epitaxially grown on SrTiO3 (001) substrates buffered with SrRuO3 films as bottom electrode by pulsed laser deposition under high oxygen pressure of 30 Pa. The quality of the BaTiO3/SrRuO3/SrTiO3 multilayer films was analyzed by means of X-ray diffraction, atomic force microscopy and transmission electron microscopy. BaTiO3 films were found to be highly c-axis-oriented tetragonal phase with c/a = 1.002. The dielectric constant first increased with increasing temperature, and showed a peak at the Curie temperature of about 356 K. The films had well-saturated hysteresis loops with a remnant polarization of 7.3 μC/cm2 and a coercive field of 29.5 kV/cm at room temperature. 相似文献
17.
G. Balakrishnan S. Tripura Sundari V. Ganesan D. Sastikumar 《Thin solid films》2010,518(14):3898-9914
Preparation of γ-alumina thin films by pulsed laser deposition from a sintered α-alumina target is investigated. The films were deposited on (100) silicon substrates at 973 K with varying oxygen partial pressures in the range 2.0 × 10−5-3.5 × 10− 1 mbar. X-ray diffraction results indicated that the films were polycrystalline γ-Al2O3 with cubic structure. The films prepared in the oxygen partial pressure range 2.0 × 10− 5-3.5 × 10− 2 mbar contained nanocrystals of sizes in the range 10-16 nm, and became amorphous at pressures > 3.5 × 10− 1 mbar. Topography of the films was examined by atomic force microscopy using contact mode and it showed the formation of nanostructures. The root-mean square surface roughness of the film prepared at 2.0 × 10− 5 mbar and 3.5 × 10− 1 mbar were 1.4 nm and 3.5 nm, respectively. The thickness and optical properties were studied using ellipsometry in the energy range 1.5-5.5 eV for three different angles of incidence. The refractive index was found to decrease from 1.81 to 1.73 with the increase of oxygen partial pressures from 2.0 × 10− 5 to 3.5 × 10− 2 mbar. The variation in the refractive index has been found to be influenced by the microstructure of the films obtained as a function of oxygen partial pressure. 相似文献
18.
Jung Pil Noh Ki Taek Jung Tae Hoon Kwon Gyu Bong Cho Sun Chul Huh Byeong Keun Choi Ki Won Kim Tae Hyun Nam 《Materials Research Bulletin》2013
LiCoO2 single-layer and LiCoO2/LiNiO2 multi-layer thin film electrodes were successfully fabricated by magnetron sputtering. Their microstructure and electrochemical properties were investigated. Once annealed, both films had the (0 0 3) preferred orientation to minimize the surface energy. The initial discharge capacity of the multi-layer thin film was approximately 53.1 μAh/cm2 μm, which was higher than that of the LiCoO2 single-layer thin film having similar thickness. The capacity retention of the multi-layer thin film was superior to that of the single-layer thin film. These findings indicate that the multi-layer thin film is a promising cathode material for the fabrication of high-performance thin film batteries. 相似文献
19.
Cu-In-Te based thin films were grown onto soda-lime glass (SLG) substrates at 200 °C by co-evaporation using a molecular beam epitaxy system. The microstructural properties were examined by means of scanning electron microscopy, X-ray diffraction and Raman scattering. The crystalline quality of Cu-In-Te based thin films with high Cu/In ratios is superior to that of films with low Cu/In ratios. The films with Cu/In ratios of 0.69 ± 0.04 exhibited a single chalcopyrite phase with random orientation, whereas a defect chalcopyrite phase with a preferred (112) orientation was obtained for thin films with Cu/In ratios of 0.26 ± 0.02. However, the films with high Cu/In ratios of 0.69 ± 0.04 showed nearly constant low resistivity (∼ 10− 2 Ω cm) at temperatures from 80 to 400 K due to high hole concentration (> 1019 cm− 3), resulting in semi-metallic behavior. The hole conduction mechanism of the film (Cu/In atomic ratios = 0.26 ± 0.02) with semi-conductive properties was found to be variable-range-hopping of the Mott type in the wide range of 80-300 K. The optical bandgaps of Cu-In-Te based thin films are determined to be 0.93-1.02 eV at 300 K from transmission and reflection measurements. A solar cell with a ZnO/CdS/CuIn3Te5/Mo/SLG structure showed a total area (0.50 cm2) efficiency of 5.1% under AM1.5 illumination (100 mW/cm2) after light soaking. The conduction band offset at the CdS/CuIn3Te5 interface was estimated to be − 0.14 eV from X-ray photoelectron spectroscopy analysis. 相似文献
20.
Morched Zribi 《Thin solid films》2011,519(11):3865-3869
Na-doped CuInS2 material is obtained by the incorporation of the sodium of an atomic percentage in amounts of 0, 0.1, 0.5, 1, 2 and 3% with a stoechiometric mixture of the elements copper, indium and sulfur taken in the stoechiometric proportions. We have investigated in this work the effect of intentional Na-incorporation on the structural, optical and electrical properties of CuInS2:Na-doped thin films grown by the single source thermal evaporation method. In the resulting Bridgman-grown ingots brittleness were increased with increased Na and measured hot point probe changed sign from p- to n-type in stoechiometric ingots above 0.5 at.%. The samples having a low Na atomic percentage exhibit better crystallinity that shows the effect of the sodium for the larger percentage to degrade the crystallinity of layers (atomic percentage greater than 2 at.%). The film conductivity was strongly affected by Na-doping, which increased from 10− 6 to 10− 3 S/cm by increasing [Na]/[CuInS2] ratio from 0.1 to 3 at.%. Indeed for an atomic percentage Na of 1% we obtained the biggest thickness (1 μm) corresponds to the lowest refractive index value (2.08). 相似文献