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Thin films of PbSe of 400-600 nm in thickness, were obtained via chemical deposition from a solution containing lead nitrate, thiourea and selenosufate. SnSe thin films of 90-180 nm in thickness, were also obtained by chemical dep...
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Thin films of PbSe of 400-600 nm in thickness, were obtained via chemical deposition from a solution containing lead nitrate, thiourea and selenosufate. SnSe thin films of 90-180 nm in thickness, were also obtained by chemical deposition from a solution containing selenosulfate. Optical and electrical properties of these thin films were significantly altered by heating them in selenium vapor at 300 degrees C. Thin film PbSe has a bandgap (E-g) of 1.17 eV (direct gap, forbidden transitions), which decreases to 0.77 eV when it has been heated. Its electrical conductivity (sigma) is p-type: 0.18 Omega(-1) cm(-1) (as-prepared), and 6.4 Omega(-1) cm(-1) when heated. Thin film SnSe is of orthorhombic crystalline structure which remains stable when heated at 300 degrees C, but its Eg increases from 1.12 eV (indirect) in as-prepared film to 1.5 eV (direct, forbidden transitions) upon heating. Its electrical conductivity is p-type, which increases from 0.3 Omega(-1) cm(-1) (asprepared) to 1 Omega(-1) cm(-1) when heated (without Se-vapor). When SnSe film is heated at 300 degrees C in the presence of Se-vapor, they transform to SnSe2, with E-g of 1.5 eV (direct, forbidden) with n-type electrical conductivity, 11 Omega(-1) cm(-1). The Seebeck coefficient for the PbSe films is: + 0.55 mV K-1 (as prepared) and + 0.275 mV K-1 (heated); for SnSe films it is: + 0.3 mV K-1 (as prepared) and + 0.20 mV K-1 (heated); and for SnSe2 film,-0.35 mV K-1. A five-element PbSe-SnSe2-PbSe-SnSe2-PbSe thermoelectric device demonstrated 50 mV for a temperature difference Delta T =. 20 degrees C (2.5 mV K-1). For SnSe-SnSe2-SnSe-SnSe2-SnSe device, the value is 15 mV for Delta T =. 20 degrees C (0.75 mV K-1). Prospect of these thin films in thermoelectric devices of hybrid materials, in which the coatings may be applied on distinct substrate and geometries is attractive.
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On-chip integrated solenoid inductors with nanogranular FeCoTiO magnetic cores have been fabricated. Both single-layered and multilayered magnetic cores with different geometries were studied. An inductance of 14.2 nH was achieved...
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On-chip integrated solenoid inductors with nanogranular FeCoTiO magnetic cores have been fabricated. Both single-layered and multilayered magnetic cores with different geometries were studied. An inductance of 14.2 nH was achieved when using a multilayered core structure and keeping the device area of 0.14 mm2. The inductance of the magnetic core inductor is times that of the air core inductor, and the quality factor is 7.5. The permeability trends calculated from inductance were compared with the permeability spectra of the patterned FeCoTiO films measured by an improved shorted microstrip transmission line perturbation method. Consistent results have been obtained after considering the demagnetization effect of the magnetic core with high permeability.
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In the present work we report the characterization of PbO-GeO_2 films containing silver nanoparticles (NPs). Radio Frequency (RF) co-sputtering was used for deposition of amorphous films on glass substrates. Targets of 60PbO-40GeO...
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In the present work we report the characterization of PbO-GeO_2 films containing silver nanoparticles (NPs). Radio Frequency (RF) co-sputtering was used for deposition of amorphous films on glass substrates. Targets of 60PbO-40GeO_2 (in wt%) and bulk silver with purity of 99.99% were RF-sputtered using 3.5 m Torr of argon. The concentration of silver and gold NPs in the films was controlled varying the RF-power applied to the targets (40-50 W for the PbO-GeO_2 target; 6-8 W for the metallic target). The films obtained were annealed in air at different temperatures and various periods of time. Absorption measurements have shown strong NPs surface plasmon bands. Different widths and peak wavelengths were observed, indicating that size, shape and distribution of the silver NPs are dependent on the deposition process parameters and on the annealing of the samples. X-Ray Fluorescence and Transmission Electron Microscopy were also used to characterize the samples.
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Despite important progress in the field of the thin flexible transistor(TFT)-based electronics,a major challenge still exist for organic TFTs to decrease the operating voltage,which is related to the properties of the dielectric a...
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Despite important progress in the field of the thin flexible transistor(TFT)-based electronics,a major challenge still exist for organic TFTs to decrease the operating voltage,which is related to the properties of the dielectric and semiconductor layers from the OTFTs structure.In this paper,we present the electrical behavior of two biocompatible polymers,polyvinylpyrrolidone(PVP 360)and polyvinyl alcohol(PVA),regarding the application as insulating layer in thin-film transistors.The PVA and PVP 360 thin films were deposited onto epoxy resin copper double-sided layer and polyethylene tere-phthalate/Indium tin oxide(PET/ITO)substrates by sol-gel method,spin-coating technique.Two sol concentrations(1 and 5 wt.%)were prepared and the contact angle onto the used substrates was measured using a digital microscope camera.The obtained films have been characterized by scanning electron microscopy(SEM)and dielectrical behaviour.For electrical measurements,the metal-insulating-metal(MIM)structure was realized by cooper electrodes deposition at room temperature,onto the top of thin films,by magnetron sputtering method.The current(I)-applied voltage(from-5 to+5 V)curves were measured in air at room temperature(RT),using the Picoammeter homemade device.PVA and PVP 360 thin films showed low leakage currents with values within ± 2 nA for ±5 V range.
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The nonlinear optical properties of GeSeTe (, 10, 20, 30, 40, 50) thin films have been investigated as a function of composition and substrate deposition temperatures (303, 363, and 423 K). The third-order nonlinear susceptibility...
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The nonlinear optical properties of GeSeTe (, 10, 20, 30, 40, 50) thin films have been investigated as a function of composition and substrate deposition temperatures (303, 363, and 423 K). The third-order nonlinear susceptibility and nonlinear refractive index have been estimated. Nonlinearity in refractive index increases with Te content and also with increasing substrate temperature. Among the investigated compositions of GeSeTe, the GeSeTe composition shows more prominent nonlinear refractive index in comparison with pure silica. The high third-order susceptibility and nonlinear refractive index may make these materials capable for high-speed communication fibers.
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The single-sided and dual-sided high reflective mirrors were deposited with ion-beam sputtering (IBS). When the incident light entered with 45°, the reflectance of p-polarized light at 1064 nm exceeded 99.5%. Spectrum was gained ...
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The single-sided and dual-sided high reflective mirrors were deposited with ion-beam sputtering (IBS). When the incident light entered with 45°, the reflectance of p-polarized light at 1064 nm exceeded 99.5%. Spectrum was gained by spectrometer and weak absorption of coatings was measured by surface thermal lensing (STL) technique. Laser-induced damage threshold (LIDT) was determined and the damage morphology was observed with Lecia-DMRXE microscope simultaneously. The profile of coatings was measured with Mark Ⅲ-GPI digital interferometer. It was found that the reflectivity of mirror exceeded 99.9% and its absorption was as low as 14 ppm. The reflective bandwidth of the dual-sided sample was about 43 nm wider than that of single-sided sample, and its LIDT was as high as 28 J/cm~2, which was 5 J/cm~2 higher than that of single-sided sample. Moreover, the profile of dual-sided sample was better than that of substrate without coatings.
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Using a new kind of EH1000 ion source, hafnium dioxide (HfO_2) films are deposited with different deposition techniques and different conditions. The absorbance and the laser damage threshold of these films have been measured and ...
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Using a new kind of EH1000 ion source, hafnium dioxide (HfO_2) films are deposited with different deposition techniques and different conditions. The absorbance and the laser damage threshold of these films have been measured and studied. By comparing these characteristics, one can conclude that under right conditions, such as high partial pressure of oxygen and right kind of ion source, the ion-assisted reaction deposition can prepare HfO_2 films with higher laser induced damage threshold.
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The single-and multi-shot damage behaviors of HfO_2/SiO_2 high-reflecting (HR) coatings under Nd:YAG laser exposure were investigated. Fundamental aspects of multi-shot laser damage, such as the instability due to pulse-to-pulse a...
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The single-and multi-shot damage behaviors of HfO_2/SiO_2 high-reflecting (HR) coatings under Nd:YAG laser exposure were investigated. Fundamental aspects of multi-shot laser damage, such as the instability due to pulse-to-pulse accumulation of absorption defect and structural defect effect, and the mechanism of laser induced defect generation, are considered. It was found in multi-shot damage, the main factors influencing laser-induced damage threshold (LIDT) are accumulation of irreversible changes of structural defects and thermal stress that induced by thermal density fluctuations.
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The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode. The absorption measurement of such coatings has been perfor...
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The laser-induced damage behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running laser mode. The absorption measurement of such coatings has been performed by surface thermal lensing (STL) technique. The relationship between damage morphology and absorption under the two different laser modes was studied in detail. The explanation was given by the standing-wave distribution theory.
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Two-dimensional films comprising of Bi clusters ranging in size from 25 to 100 Angstrom show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature T-c. This is in contrast...
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Two-dimensional films comprising of Bi clusters ranging in size from 25 to 100 Angstrom show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature T-c. This is in contrast to crystalline Bi. Quantum size effects are observed by changing the deposition temperature, which determines the cluster size. These observations can be attributed to superconductivity at the surface. Implications for the requirement of a critical number of superconducting clusters before the establishment of global phase coherence are briefly discussed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 14]
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