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NiS{sub}2 thin films for photovoltaic applications have been deposited from the elements S and Ni. Their structural, optical and electrical properties have been investigated and compared with those of single crystals. The depositi...
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NiS{sub}2 thin films for photovoltaic applications have been deposited from the elements S and Ni. Their structural, optical and electrical properties have been investigated and compared with those of single crystals. The deposition technique used here is suitable for growing films on large area substrates and it can be used easily and fruitfully to grow other chalcogenide compounds.
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Three-dimensional (3D) nanostructured Sn_2S_3 semiconductor films have been prepared on ITO-coated glass substrates by potentiostatic electrodeposition at -0.80 V (vs. SCE) from a novel plating bath containing K_4P_2O_3 as a compl...
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Three-dimensional (3D) nanostructured Sn_2S_3 semiconductor films have been prepared on ITO-coated glass substrates by potentiostatic electrodeposition at -0.80 V (vs. SCE) from a novel plating bath containing K_4P_2O_3 as a complexing agent and Na_2SO_3 as a stabilizing agent and by subsequent annealing. Results showed that the annealing drove the as-deposited Sn_2S_3 films to grow from a granular structure into a nanorod network structure. The nanorods were around 50-100 nm in diameter and 1000 nm in length. The band gap of the annealed film was 1.65 eV and the conductivity was n type. The carrier mobility achieved up to 20.5 cm2 V~(-1) s~(-1) due to the direct electrical pathways provided by the nanorod network.
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Pure ZnO and doped thin films with different weights of Barium chloride BaCl2 (0.01,0.02 and 0.03 gm) have been prepared using chemical bath deposition method CBD. The prepared films were characterized by ultraviolet –Visible (UV...
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Pure ZnO and doped thin films with different weights of Barium chloride BaCl2 (0.01,0.02 and 0.03 gm) have been prepared using chemical bath deposition method CBD. The prepared films were characterized by ultraviolet –Visible (UV) and scanning electron microscope. the transmittance was decreases with increasing of BaCl2 concentration especially at weight (0.03gm) and the energy gap of pure ZnO films was found of about 3eV and decreases to 2.8eV at 0.03gm of BaCl2. The SEM images of pure ZnO thin films show a formation of clusters, while the images of the doped layers show Linear nanostructures and their clarity and densities increases with increasing BaCl2 weight.
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Silicon nitride film deposited by LPCVD with newly developed in situ HF vapor cleaning has been studied and applied to fabricate dielectric films for stacked DRAM capacitors. Using this method, an oxide-free surface of underlaid p...
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Silicon nitride film deposited by LPCVD with newly developed in situ HF vapor cleaning has been studied and applied to fabricate dielectric films for stacked DRAM capacitors. Using this method, an oxide-free surface of underlaid poly-Si can be obtained. Silicon nitride film deposited on this surface has been verified by FTIR measurement to have the stoichiometrically proper composition of Si/sub 3/N/sub 4/. However, the film was found to be selectively deposited on poly-Si electrodes. This selective deposition degrades the reliability of the stacked capacitor, because the silicon nitride can not completely cover the periphery of poly-Si electrodes on SiO/sub 2/. We propose a simple process that avoids the problem making it possible to apply silicon nitride film to stacked-capacitor fabrication. Stacked capacitors fabricated by this process exhibit very low leakage current and high electrical reliability even for ultra-thin silicon nitride films less than 5 nm thick.
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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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Thin films from the Se{sub}(45.5)Ge{sub}(30.3) Tl{sub}(24.2) system have been prepared by thermal evaporation. The current-voltage characteristics in the temperature range 290373 K and the thickness range 98-400 nm are ohmic in th...
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Thin films from the Se{sub}(45.5)Ge{sub}(30.3) Tl{sub}(24.2) system have been prepared by thermal evaporation. The current-voltage characteristics in the temperature range 290373 K and the thickness range 98-400 nm are ohmic in the lower field regime followed by non-ohmic behaviour in the higher voltage regime which has been satisfactorily explained by the anomalous Poole-Frenkel effect. The effects of temperature on the dielectric constant have been studied. The dependence of the electrical conductivity, on exposure to different durations of light and on temperature has been studied. The activation energy was found to decrease with increasing periods of light exposure.
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In this work, we systematically investigated the properties of three kinds of NiOx films prepared by magnetron sputtering either NiO or Ni target under direct current (DC) or radio frequency (RF) power without any preheating. Thos...
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In this work, we systematically investigated the properties of three kinds of NiOx films prepared by magnetron sputtering either NiO or Ni target under direct current (DC) or radio frequency (RF) power without any preheating. Those NiOx films were found to be different in composition ratios, lattice strain and energy levels, thus showing different optical and carrier transport properties. By RF power source, sputtering Ni target in pure O-2 atmosphere led to NiOx film with relatively good crystallization and surface properties compared with other two types of NiOx films. These NiOx films were further introduced into CH3NH3PbI3 based planar p-i-n heterojunction perovskite solar cells (PSCs) as the hole transport layers (HTL). It is revealed that PSCs based on NiOx HTL prepared by sputtering Ni target in pure O-2 atmosphere achieved a highest power conversion efficiency of 16.3% with negligible hysteresis. Compared with devices with PEDOT:PSS HTL, PSCs based on magnetron sputtered NiOx HTL presented substantially improved stability in air. The results provide theoretical and experimental guidance on selecting NiOx HTLs fabricated by magnetron sputtering techniques.
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Tin(IV) selenide (SnSe2) thin films 120-280 nm in thickness are obtained through heating SnSe films at 350 degrees C, in the presence of Se-vapor. Thin film of SnSe deposited from a chemical bath is of orthorhombic crystal structu...
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Tin(IV) selenide (SnSe2) thin films 120-280 nm in thickness are obtained through heating SnSe films at 350 degrees C, in the presence of Se-vapor. Thin film of SnSe deposited from a chemical bath is of orthorhombic crystal structure, with a band gap, E-g, of 0.94 eV, and p-type conductivity of 0.3 Omega(-1) cm(-1). Thin film of SnSe2 280 nm in thickness of hexagonal crystalline structure, with E-g of 1.2 eV and n-type electrical conductivity of 2 Omega(-1) cm(-1) is produced from SnSe film 260 nm in thickness. The SnSe2 film shows a Hall mobility of 10 cm(2)/(V s), carrier (electron) concentration 10(17)-10(18) cm(-3) and thermoelectric power of -390 mu V/K. The thin film of SnSe2 formed this way is stable during further heating at temperatures up to 430 degrees C, but it reverts to p-type SnSe thin film when heated at 530 degrees C. Applications of these SnSe and SnSe2 thin films are considered. (C) 2015 Elsevier B.V. All rights reserved.
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The growth of manganese (Ⅱ) sulfide films by radiofrequency sputtering are shown for the first time. Polycrystalline, nearly stoichiometric films of the metastable hexagonal γ-MnS phase were obtained when the substrate temperat...
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The growth of manganese (Ⅱ) sulfide films by radiofrequency sputtering are shown for the first time. Polycrystalline, nearly stoichiometric films of the metastable hexagonal γ-MnS phase were obtained when the substrate temperature was approximately 26 deg. C. For higher substrate tem- peratures, 120 and 180 deg. C, the films wer amorphous and sulfur deficient. The sulfur loss is substrate-temperature dependant. This behavior is discussed in terms of the dissociation of the MnS molecules during the sputtering process and the phase diagram of sulfur.
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In this paper, the simulation models of gallium nitride nanostructure arrays are designed by COMSOL Multiphysics software based on finite element method. The effects of changes of GaN nanowires in axial geometry on photoelectron c...
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In this paper, the simulation models of gallium nitride nanostructure arrays are designed by COMSOL Multiphysics software based on finite element method. The effects of changes of GaN nanowires in axial geometry on photoelectron concentration distributions performance and absorptivity are analyzed. The results pointed out that both truncated-corn and inverted-pencil arrays have the ability of boosting light absorption compared to nanorod arrays. (c) 2020 Elsevier B.V. All rights reserved.
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