Studies on thin films of cadmium sulphide prepared by a chemical deposition method

A new method of chemical deposition consisting of the formation of thin films of a substance at the interface of a solution and a gas was used to form thin films of semiconducting and photoconducting CdS. The structural, electrical and optical properties of these films were studied. A special feature is the cubic zinc-blende structure of the films. A possible explanation for the optical and electrical properties of these films is given.     

Structural, optical and electrical characterization of selenium sulphide nanostructured thin film

Thin film of selenium sulphide (Se₇₅S₂₅) has been prepared using inert-gas consolidation (IGC) method and micro-structural, optical and electrical measurements were carried out on the film. Scanning electron microscopy (SEM) studies show that the deposited film is well adherent and grains are uniformly distributed over the surface of the substrate. X-ray diffraction (XRD) analysis shows that the film is polycrystalline nature with single phase and crystallizes in the orthorhombic structure. The field emission transmission electron microscope (FETEM) revealed the uniform dispersion and an average particle size of 20 nm. Analysis of the optical absorption data indicates that the optical band gap E_opt of this film obeys Tauc's relation for the allowed non-direct transition with energy gap is 2.48 eV. Electrical conduction measurements also show the presence of two distinct phases of the materials and characteristic changes in transport properties due to the nanosize of the materials.     

Characterization of cadmium sulphide thin films prepared by successive ionic layers adsorption and reaction method

Cadmium sulfide (CdS) thin films were deposited on glass substrate at room temperature by successive ionic layer adsorption and reaction method (SILAR). The deposition parameters such as rinsing time, rinsing cycle and concentration of precursor solution were varied during the preparation of the samples. The structural characterization and optical characterization were carried out. The deposited films by lower growth rate and lower precursor concentration solutions were having mixed hexagonal and cubic phases. Thickness dependence of the optical band gap energy was evaluated and it varies from 2.46 to 2.32 eV in the thickness range 38–330 nm.     

A new method for the exploration and measurement of crack growth using a thin conductor film

A method has been developed in which the length of a crack on any metallic or non-metallic surface can be measured in situ, simply and at low cost. This is done by applying a thin, conducting film to the surface and then measuring the increase in voltage that occurs as the crack lengthens.     

二氧化锡薄膜的MOD法制备和表征

采用新颖的金属有机物热分解方法（MOD）制备了二氧化锡薄膜,红外分析和热分析表明,先体制备过程中生成了锡的有机物,这对制备质量良好的光学薄膜起了决定作用。对薄膜的红外光谱和紫外－可见光谱的分表明,薄的热处理过程中经历了溶剂挥发、有机物燃烧和析晶等过程,随热处理温度的升高,薄膜的孔率显著减小,薄的结构致密,这是由制备过程的特点决定的。     

A new approach to the manufacture of chalcogenide thin film solar cells

Glass beads of 0.2 mm diameter are covered with molybdenum, copper and indium. The copper/indium layers are transformed into copper indium disulfide (CIS) by exposing the glass beads to a hydrogensulfide/argon mixture at temperatures of around 500 °C. The CIS covered glass beads serve as the basis material for the formation of solar cells. The main advantage of this approach is the separation between absorber and cell/module formation. In this paper the different process steps necessary for cell manufacturing are described. Some properties of solar cells made out of CIS covered glass beads are presented.     

Room temperature synthesis and characterization of polythiophene thin films by chemical bath deposition (CBD) method

Polythiophene thin films were deposited successfully on glass substrate by chemical bath deposition method using FeCl₃ as an oxidant and chloroform as solvent. The effect of oxidant concentration on the properties of polythiophene thin films was studied. The surface morphology was influenced by oxidant concentration and deposition time. The oxidation concentration also strongly affects the optical properties of the polythiophene thin films. The transmittance decreases while the absorption, band gap and refractive index increases due to increase in oxidant concentration.     

Indentation mechanics and its application to thin film characterization

Instrumented indentation mechanics and its applications to thin film characterization are described and discussed. Instrumented nanoindentation has become an outstanding tool for characterizing coatings and treated surfaces. It is routinely used in industry and university allowing for determining the mechanical performance of coated and treated pieces, that is of primary importance for keeping new surface functionality in time. The paper reviews important procedures and concepts that have proved to be very useful to analyse the contact response (elastic unloading, indentation strains and stresses, composite response of coated pieces). Examples are used to illustrate the very wide range of studies that can be carried out.     

Photocatalytic degradation of methylene blue using novel flower-like zirconium bismuth molybdate thin film,grown by temperature-assisted CBD method

Thin films of a novel metal molybdate are successfully coated on soda lime glass by one step chemical bath deposition method. The deposition is carried out under different bath temperature ranging from 30 to 70 °C. In order to analyze the crystalline structure, X-ray diffraction study is carried out. Film thickness and morphology are examined through atomic force microscope and scanning electron microscope. Optical studies are done by UV–Vis–NIR absorbance spectra and photoluminescence spectra. All the samples have absorbance in the UV–Vis region and possess direct allowed transition with bandgap values ranging from 2.17 to 2.83 eV. Direct current show good ohmic response and possess resistivity in the range characteristic of wide bandgap materials. The material possesses three major photoluminescence emission peaks in the green and blue wavelength regions. Thin film grown at 50 °C showed increased absorbance width, minimum bandgap energy, larger electron–hole separation efficiency and more porous flower-like morphology which indicates its higher photocatalytic ability. The photocatalytic degradation process for the removal of methylene blue from waste water, under sunlight irradiation using thin film grown at 50 °C as photocatalyst has been discussed in detail.

     

Optical and electrical characterization of fluorine doped cadmium oxide thin films prepared by the sol-gel method

Highly transparent and conducting fluorine (F) doped cadmium oxide (CdO) thin films were deposited on glass slides by the sol-gel method. The films were doped by the addition of ammonium fluoride to the precursor solution whose optimum concentration was determined. The films were fired in an open atmosphere at 350 °C and after that, exposed to annealing treatments in different atmospheres (N₂, N₂/H₂ mixture and Ar) at the same temperature. The films were characterized by ultraviolet-visible spectroscopy, X‐ray diffraction and scanning electron microscopy. The resistivity was determined by the four probes method and current-voltage measurements in accordance with the standard Van der Pauw configuration. The CdO:F thin films obtained, showed high polycrystalline quality and high transmission in the visible region (≥ 90%), shifting towards the blue region of the absorption edge as the fluorine concentration in the precursor solution was increased from 0 to 30 at.%. The lowest resistivity values were reached for the samples with F content higher or equal to 5% and annealed in either N₂ or a 96/4 N₂/H₂ gas mixture. Our resistivity value reached in the CdO:F layers was 4.5 × 10^{− 4} Ω cm (20 Ω/square).     

Chemical bath deposition of cadmium sulphide on silicon nitride: Influence of surface treatment on film growth

Nanoparticulate cadmium sulphide was grown by a chemical bath method on PECVD silicon nitride with various surface treatments. It was found that the packing density of the film increased in the order: untreated surface < mercaptopropyl-derivatised surface < ultra-thin (discontinuous) gold- or platinum-treated surface. This behaviour was rationalised by assuming that surface concentrations of Cd²⁺ or S²⁻ could be increased over the bulk values by producing a surface with ‘soft base’ or ‘soft acid’ chemistry, respectively.Nanoparticle diameters were larger with ultra-thin platinum treatment than with gold. These observations may allow ordered arrays of cadmium sulphide nanoparticles to be prepared by a masking - gold seeding - bath deposition procedure.     

BaMoO4薄膜在电化学法制备中生长基元的实验研究

在采用恒电流电化学技术研究BaMoO4薄膜的初期生长特性实验中,发现了若干很重要的实验现象:薄膜生长初期形成的晶核首先具有白钨矿结构的骨架;晶核和刚开始长大生成的晶粒都是疏松的,晶粒都明显显示有蜂窝状空隙存在;随着制备时间的增加,白钨矿结构骨架原先疏松的程度逐渐减弱,经过一定时间,晶粒趋于饱满,晶粒表面基本光滑;在薄膜形成的过程中,新生成的晶核也具有类似情况.结合BaMoO4薄膜电化学制备机制分析,作者认为:利用电化学技术制备BaMoO4晶态薄膜时,在生长初期基体Mo以[MoO4]2-的形式构成负离子配位多面体生长基元,这些生长基元优先选择在基体缺陷处作为白钨矿结构的晶核堆砌和生长,并进而与溶液中的[Ba]2 相连接,键合成BaMoO4晶粒,再逐渐长大.显然,该发现和研究对于丰富晶体生长动力学知识及指导利用电化学技术制备晶态薄膜都具有重要意义.     

Preparation and characterization of chemically deposited lead sulphide thin films

A chemical method for the deposition of PbS thin films has been developed using appropriate amounts of lead acetate, thioacetamide and triethanolamine. The thickness of the films are in the range 0.3 to 1 m. The films are polycrystalline and p-type. The dependence of the film thickness as a function of the bath parameters has also been studied and explained on the basis of ion-ion condensation theory.     

Metalorganic chemical vapor deposition of SrRuO3 thin film and its characterization

Synthesis of conducting oxide strontium ruthenate is carried out in a hot-wall tubular reactor, using Sr(C₁₁H₁₉O₂)₂/Ru(C₅H₅)₂/O₂ reaction system. Owing to a large difference in depositing efficiency between strontium and ruthenium precursors, the stoichiometric ratio of thin film is controlled in one cycle of two consecutive depositions at different temperatures. Thin films of SrRuO₃ single phase are synthesized in the subsequent 700°C annealing. Thin films of SrRuO₃ with extra ruthenium oxide can also be prepared by adjusting the molar ratio of RuO₂ and SrO layers. The deposition sequence of ruthenium oxide first, strontium oxide later is preferred. If the deposition sequence is reverse, the thin film is plagued with unreacted oxides even when the annealing temperature is raised to 800°C. The relative ease of preparing SrRuO₃ thin films, when RuO₂ is under SrO, is attributed to evaporation of ruthenium oxide in O₂ and diffusion in its open columnar microstructure. The sheet resistivity of thin film decreases with the ruthenium content. The room temperature resistivity of SrRuO₃ film of Ru/(Sr + Ru) = 0.5 is around 910 ohm-cm. The room-temperature resistivity of Ru/(Ru + Sr) = 0.53 decreases to 470 ohm-cm. The root mean square surface roughness of 700°C synthesized SrRuO₃ thin film is 22 nm, in a 2 × 2 m² area of film thickness 280 nm.