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Chemical Bath Deposition (chemical + bath_deposition)
Selected AbstractsChemical bath deposition of CdSe and CdS nanocrystalline films: tailoring of morphology, optical properties and carrier dynamicsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008Abstract We review the results of our research towards tailoring morphology and optical properties of films consisting of closely-spaced nanocrystals of CdSe and CdS whose optical band-gap can be tuned to cover the whole visible spectral range. On basis of the obtained results, in particular of photoexcited carrier dynamics, we have proposed a microscopic model that describes well the optical properties of the films. We have also showed that the spin relaxation of electrons in these nanocrystalline films is different than that in mutually isolated nanocrystals of the same size. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanomechanical Properties of Bioinspired Organic,Inorganic Composite Films,ADVANCED MATERIALS, Issue 7 2007Z. Burghard Nacre-like thin films are fabricated via a bioinspired route combining chemical bath deposition of the inorganic component (TiO2) and layer-by-layer alternate adsorption of oppositely charged polyelectrolytes for the organic component (see figure). Nanoindentation testing revealed an increase in hardness and Young's modulus imparted by the alternate-layer architecture of the composite films. [source] Electrodeposition of Titania Thin Films on Metallic Surface for High- k Dielectric ApplicationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Biplab K. Roy Current microelectronics devices based on flexible as well as rigid substrates demand high dielectric constant (k) films to be grown on conductive substrate from a low-cost, low-temperature deposition technique. In this study, we produced high- k titania (TiO2) films through an affordable electrodeposition protocol from the electrochemical bath maintained at about 0°C. The deposition occurs through a rapid hydrolysis mechanism of titanium containing ions in the precursor solution aided by electrochemically generated hydroxyl ions formed near the cathode surface (copper (Cu) substrate). Upon attaining a sufficient supersaturation level, such hydrolyzed species precipitate to form a titania thin film on the cathode surface. While depositing from a highly acidic precursor solution, Cu substrate was protected by a cathodic potential (,3 to ,5 V against the counter electrode). The resultant titania films show nanoparticulate structures evolved from nucleation and growth events of the in situ precipitated particles. Much higher deposition rate (about 1 ,m/min) was observed compared with that of typical chemical bath deposition. The resultant films with a thickness of 1500 nm grown on Cu exhibit very high dielectric properties (e.g., k,30, capacitance density >110 nF/in.2 at 100 kHz) and moderate breakdown voltage (VB) (,17.5 V). These properties indicate the potential of electrodeposited titania films to be used as a small-area thin-film capacitor for miniaturized electronic devices. [source] Unique structure of ZnO films deposited by chemical bath depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2009Dewei Chu Abstract The unique structure of ZnO films obtained from aqueous solution method was investigated. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analyses indicate that unique morphology and structure of the region where precipitation on the substrate may occur in parallel with other regions. This is accompanied by a decrease of the electrical resistivity in the absorbed region. A possible mechanism for the resistivity transformation was discussed. [source] Growth and electrical properties of ZnO films prepared by chemical bath deposition methodPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2009Dewei Chu Abstract The influence of the choice of temperature, pH value, counter-ion, deposition time, and seed layer on the morphology as well as electrical properties of ZnO films grown from chemical bath deposition (CBD) are discussed. Consequently, oriented ZnO films with various microstructures can be synthesized by controlling the solution pH value and counter-ions. Besides, the point at which the seed layer is pre-heated at higher temperature is crucial and can lead to a significant difference in the width of crystals and electrical properties of ZnO films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Enhancement of luminescence in ZnMgO thin-film nanophosphors and application for white light generationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2008Santa Chawla Abstract A series of ZnMgO thin-film nanophosphors with varied Zn:Mg ratio has been prepared by chemical bath deposition. The structure, photoluminescence, time-resolved decay and chromaticity of the films are presented. ZnMgO films absorb light efficiently in the near UV (330,400 nm) and the emission covers a large part of the visible spectrum. Luminescence enhancement is maximum for 25% Mg. All ZnMgO films show luminescence lifetimes in the microsecond range while low Mg content (0,10%) films also exhibit fast decay (10,10 s). Measured colorimetric coordinates of (0.28, 0.32) when excited by 350 nm light make them suitable for generation of white light in conjunction with near UV LEDs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of a polymeric solution buffer layer on the chemical bath deposition of polycrystalline PbS filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005Y. González-Alfaro Abstract Polycrystalline thin films of PbS grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution were obtained by chemical bath deposition (CBD). The X-ray diffraction procedures showed evidence of polycrystalline films of cubic PbS with a preferred normal orientation of the planes [100] with the growth direction. The film texture showed a strong influence of the initial conditions of the surface. Moreover, changes in colour, morphology and grain size of the films were observed by optic and atomic force microscopy (AFM). Rutherford backscattering spectrometry (RBS) showed a dependence of the thickness and roughness of the PbS films with the growth initial conditions. A kinetic growth model is proposed to explain the changes in the structure and morphology of the PbS. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of annealing temperature on the crystalline quality and phase transformation of Chemically Deposited CdSe filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005M. Zapata-Torres Abstract Polycrystalline CdSe thin films were grown on glass substrates by chemical bath deposition at 50 ºC. The samples were annealed in air atmosphere at different temperatures and characterized by X-ray diffraction and Raman spectroscopy. It was found that the as-grown films have cubic structure. These samples maintain their cubic structure for annealing temperatures between 60 ºC and 300 ºC. For annealing temperatures higher than 300 ºC we obtain a mixture of cubic and hexagonal phases. The analysis made by X-ray diffraction and Raman dispersion show that the samples annealed at temperatures under the phase-transition temperature increase their crystalline quality. In order to determinate the temperature for the complete transition of the cubic phase, we used the precipitated material obtained during the grown of the CdSe films. This material was annealed on air atmosphere between 300 °C and 500 °C with 50 ° intervals. The samples were measured by X-ray diffraction. The samples maintained the cubic structure if the annealing temperature is under 300 °C. For temperatures between 300 °C and 450 °C we found a mixture of cubic and hexagonal phase. For an annealing temperature of 500°C we obtain only the hexagonal phase. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Compositional engineering of chemical bath deposited (Zn,Cd)S buffer layers for electrodeposited CuIn(S,Se)2 and coevaporated Cu(In,Ga)Se2 solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2009N. Naghavi Abstract A comparative study of chemical bath deposition (CBD) of ZnS, CdS, and a mixture of (Cd,Zn)S buffer layers has been carried out on electrodeposited CuIn(S,Se)2 (CISSe) and coevaporated Cu(In,Ga)Se2 (CIGS) absorbers. For an optimal bath composition with the ratio of [Zn]/[Cd],=,25, efficiencies higher than those obtained with CdS and ZnS recipes, both on co-evaporated CIGS and electrodeposited CISSe, have been obtained independent of the absorber used. In order to better understand the (Cd,Zn)S system and its impact on the increased efficiency of cells, predictions from the solubility diagrams of CdS and ZnS in aqueous medium were made. This analysis was completed by in situ growth studies with varying bath composition by quartz crystal microbalance (QCM). The morphology and composition of the films were studied using scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS) techniques. Preliminary XPS studies showed that films are composed of a mixture of CdS and Zn(O,OH) phases and not a pure ternary Cd1,,,xZnxS compound. The effect of the [Zn]/[Cd] molar ratio on properties of the corresponding CISSe and CIGS solar cells was investigated by current voltage [J(V)] and capacitance voltage [C(V)] characterizations. The origin of optimal results is discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Characterisation of CuInS2/ Zn(Se,O)/ZnO solar cells as a function of Zn(Se,O) buffer deposition kinetics in a chemical bathPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2002A. M. Chaparro Thin-film solar cells of CuInS2/Zn(Se,O)/ZnO configuration have been studied from the point of view of their dependence on the Zn(Se,O) chemical bath deposition (CBD) conditions. The kinetics of deposition of the Zn(Se,O) buffer is followed during cell processing with a quartz crystal microbalance (QCM). Two different CBD growth mechanisms yield buffer layers with different properties. Under a predominant electroless deposition reaction, the resulting buffer layer has mixed ZnSe,ZnO composition. The solar cells with this buffer type show higher fill factor (FF) and lower open-circuit voltage (Voc). Under a chemical growth regime, the buffer layer has higher ZnSe proportion, giving rise to cells with higher VOC, but lower FF and stability. The parameters of this second type of cell also show major dependence on illumination effects (light-soaking effects). Electron-beam-induced current (EBIC) and cathodoluminescence (CL) measurements are carried out to characterise the CuInS2/Zn(Se,O) junctions formed under the two buffer growth regimes. Cross-sectional EBIC shows a wider space charge region (SCR) than expected for p-CuInS2 in contact with Zn(Se,O), and the p,n junction is driven within the CuInS2 phase. These results reflect a chemical modification of CuInS2, most probably caused by the ammonia of the bath solution. CL shows more defective interfaces when Zn(Se,O) is deposited under the chemical mechanism (slower deposition rate, hence longer contact time of the CuInS2 with the bath solution) than under the electroless kinetics (faster deposition rate). Copyright © 2002 John Wiley & Sons, Ltd. [source] The effect of oxygen on interface microstructure evolution in CdS/CdTe solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2002D.S. Albin Microstructural changes at the CdS/CdTe solar cell interface where close-spaced sublimation (CSS) is used as the growth technique to deposit the p -type CdTe absorber layer are studied by systematic layer characterization at various stages during heterojunction growth. CdS layers grown by both chemical bath deposition (CBD) and CSS provide a basis for determining the effects of CdS crystallinity, grain size, and oxygen content on the subsequent CdTe layer. As-grown CBD CdS films exhibit small grains and variations in optical properties attributed to film impurities. In contrast, CSS yields CdS films with good crystallinity, larger grains, and nearly ideal optical properties. The hexagonal nature of CSS-grown CdS is seen to nucleate hexagonal CdTe during the initial stages of CdTe film growth. Cubic CdS deposited by CBD in contrast promotes cubic CdTe nucleation. Oxygen anneals in the latter case can aid hexagonal CdTe nucleation. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) of the CdS/CdTe interface show CdS-dependent differences in interdiffusion at the interface. This interdiffusion appears to be determined by the oxygen level in the CdS. When low-oxygen-containing CSS CdS films are used, sulfur diffusion is substantial, leading to significant consumption of the CdS layer. When these same films are annealed in oxygen, the consumption is reduced. Te diffusion into the CdS layer is also observed to decrease with oxygen anneals. Optical modeling shows that Te alloying with the CdS layer can greatly reduce the short-circuit current of CdS/CdTe devices. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||