Electrodeposition Of Thin Films Research Articles

Electrodeposition and Characterization of Hematite Films Obtained from DMSO Solution

The present study shows the results obtained in the electrodeposition of hematite thin films from DMSO solution employing FeCl3 and molecular oxygen as precursors. The films were obtained through a potential cycling program at different cathodic limits and at different electrolytic bath temperatures. In all cases, as-grown films were amorphous and photoelectrochemically inactive. An annealing procedure is necessary to completely transform the electrodeposited iron oxide to the α−Fe2O3 phase. XRD analyzes confirm the presence of diffraction peaks corresponding to hematite after annealing, showing a strong preferential orientation of the [110] axis vertical to the substrate. Different techniques (XRD, XPS, SEM, UV-Vis spectroscopy, Mott-Schottky plots and photocurrent – potential curves) have been employed in order to characterize the films and determine their properties as a function of the conditions of electrodeposition and the annealing temperature.

Electrodeposition of Heterogeneous Mn-Bi Thin Films from a Sulfate-Nitrate Bath: Nucleation Mechanism and Morphology

In this paper, we report on the nucleation and the growth of heterogeneous Mn-Bi thin films on Cu substrate from a mixed sulfate-nitrate bath using direct current plating. The electrolytic bath is characterized by the presence of ammonium sulfate which was used as complexing agent to avoid the precipitation of Mn hydroxides. Cyclic voltammetry and chronoamperometry measurements are used to study the reaction mechanisms of the Mn-Bi electrodeposition as a function of the ammonium sulfate concentration and the pH value: the optimized conditions for a stable bath are obtained for 2.5 mol. L−1 of ammonium sulfate and pH 2.3. The Scharifker and Hills (SH) model was used to analyze the current transients at the initial stage of deposition; it was revealed that Mn-Bi electrocrystallization process is governed by three-dimensional nucleation. But as the electrochemical deposition clearly involves the simultaneous presence of the proton cathodic reaction, another model developed by Palomar-Pardavé and co. was used to explain the nucleation mechanism and to describe the individual contribution of both the metallic ions and the proton reduction process. The morphology and chemical composition of the films were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The deposits have a cauliflower-shaped appearance with a heterogeneous distribution of manganese and bismuth. The energy dispersive spectroscopy analysis reveals the presence of manganese and bismuth peaks with almost the same relative intensities. The X-rays diffraction analysis shows characteristic peaks of manganese and bismuth.

Electrodeposition of High-Purity Indium Thin Films and Its Application to Indium Phosphide Solar Cells

We report on advances in the electrochemical deposition of indium (In) on molybdenum foil that enables deposition of electronic-grade purity, continuous films with thickness in the micron range. The desired In film morphology is obtained from an InCl3 aqueous bath by using a high current density of 250 mA/cm2 and a low deposition-bath temperature of −5°C to increase the nucleation density of In islands until a continuous film is obtained. As an example application, the electrodeposited In films are phosphorized via the thin-film vapor-liquid-solid growth method. The resulting poly-crystalline InP films display excellent optoelectronic quality, comparable to single crystalline InP wafers, thus demonstrating the versatility of the developed electrochemical deposition procedure.

Electrodeposition of Cu2Se Semiconductor Thin Film on Se-Modified Polycrystalline Au Electrode

This study describes the electrodeposition of thin films with a two-step approach that is based on the initial modification of polycrystalline Au electrode with a selenium overlayer followed by a cathodic stripping of the layer as in a 1 M lactic acid electrolyte containing ions. For this two-step approach to be effective, the reduction potential should be shifted to more negative potentials passed potentials for the reduction of Se to . This was accomplished by the complexation of ions with lactic acid. The resultant films were characterized by linear sweep voltammetry combined with electrochemical quartz crystal microgravimetry, UV-vis absorption spectrometry and Raman spectroscopy. Photoelectrochemical experiments revealed that synthesized thus, behaved as a p-type semiconductor.

Electrodeposition of Nanoporous Nickel Layers Using Inductive Voltage Pulses

We used inductive voltage pulses for electro-deposition of porous nickel thin film onto steel electrode. Short pulses (tp<1 μs) with variable amplitude (to ensure electro-deposition current density in region 124–224 A/dm2) were applied to electrode and resulting coating were analyzed with electrochemical and microscopic methods. At lower current densities only smooth nickel coatings growth, while at higher current densities the bubbles appear and porous layer was formed. Electrochemical impedance spectra of smooth and porous layers are measured in deionized water and in 1M KOH solution. The capacity in equivalent scheme is proportional to electrode surface, and from impedance spectra it is calculated that porous layer has 20 times larger active surface comparing to smooth layer (in KOH solution). From electrochemical measurements it is estimated that more efficient hydrogen evolution reaction occurs on electrode with porous nickel layer obtained at 223 A/dm2. It is shown in this work that inductive short pulse method can be used to obtain nano-porous nickel coatings on electrodes for efficient electrolysis cell.

Effect of composition on magnetic softness and magnetoimpedance of electrodeposited NiFe/Cu

A systematic variation of film composition was done during electrodeposition of NiFe thin films onto 100 μm diameter copper wire. Current density of deposition was maintained at 20 mA/cm2 to ensure constant film thickness. Pure Ni film as well as Fe rich NiFe film were not magnetically soft enough and showed poor magnetoimpedance effect. As Fe concentration was systematically varied, softest magnetic properties and magnetoimpedance value were found for the film composition Ni79Fe21. Soft magnetic properties induced and magnetoimpedance effect observed at this composition was attributed to the lowering of magnetoelastic anisotropy as well as magnetocrystalline anisotropy.

Electrodeposition of Gold and Polypyrrole Thin Films for Neural Microelectrodes

A low impedance electrode/tissue interface is critically important for neural microelectrodes recording to maintain signal quality. In this study, gold/polypyrrol thin films used to decrease the interface impedance. Gold thin film was electrodeposited by cyclic voltammetry in the potential range of-0.3 to 1 volt on the stainless steel surface of microelectrodes with 127 micrometer in radius. Then polypyrrole was electrodeposited on the gold layer. Electrochemical impedance spectroscopy tests were performed for impedance measurement of microelectrode surface. The effect of morphology and thickness on the impedance of thin film was studied. The results showed that the impedance of the microelectrodes with gold/polypyrrol coatings was 38.2% lower than the electrodes without coating in the neural frequency.

Cathodic Electrodeposition of Cobalt Sulfide Thin Films for Dye-Sensitized Solar Cells and Supercapacitors

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Electrodeposition of nanostructured CoNi thin films and their anomalous infrared properties

Different composition, thickness and structure of CoNi thin films supported on glassy carbon were prepared by electrochemical codeposition. Potential step method was applied to prepare CoNi thin films with different composition which was controlled by varying the concentration ratio of Co2+/Ni2+ (x:y) in the deposition solution, thus this type of CoNi thin film was defined as CoNi(x:y). Nevertheless, CoNi thin films with different thickness and structure (denoted as CoNi(n)) were synthesized in a fixed Co2+/Ni2+ solution under cyclic voltammetric conditions by varying the cyclic numbers (n) within a defined potential range. AES and EDS analysis revealed that the atomic ratio of Co/Ni in the film (including both outer and inner layer) was in good accordance with the initial Co2+/Ni2+ ratio. XRD investigation indicated that the CoNi(20:0) and CoNi(15:5) thin films were hexagonal closed-packed (hcp) structure, however, the CoNi(10:10), CoNi(5:15) and CoNi(0:20) thin films were face centered cubic (fcc) structure. SEM studies demonstrated that the CoNi(x:y) thin films were uniformly composed of irregular nanoparticles. In the case of CoNi(n), with n increasing, the structure of nanoparticles inside the CoNi thin films underwent a transition from imperfectly spherical particles to multiform particles, and finally to irregular polyhedral particles, accompany with an increase of average size. In situ FTIR reflection spectroscopic studies demonstrated that the mainly chemisorbed CO species (COad) on CoNi(x:y) surfaces were transferred from linearly bonded CO (COL) to bridge bonded CO (COB) as a function of the content of Ni and the crystal phase structure of CoNi thin films. CoNi(x:y) and CoNi(n) thin films all exhibited anomalous IR properties, corresponding respectively to abnormal IR effects (AIREs), Fano-like IR effects and surface-enhanced IR absorption effects. AIREs characterized mostly with inversion of IR band was found on CoNi(x:y), CoNi(4), CoNi(8) thin films which were dominated by irregular or imperfectly spherical particles. Fano-like IR bands with positive-going peak on the lower wavenumbers side were observed in cases of CO adsorbed on CoNi thin films composed mainly of multiform nanoparticles, typically on CoNi(25) thin film. IR features were finally changed into surface-enhanced IR absorption as CO adsorbed on the CoNi(50) thin film, i.e., the CoNi thin film was dominated by smooth irregular polyhedral particles.

Cyclic voltammetry study of electrodeposition of CuGaSe2 thin films on ITO-glass substrates

The electrodeposition mechanism of CuGaSe2 (CGS) thin films on ITO substrates has been investigated using cyclic voltammetry technique. The cyclic voltammetric study was performed in unitary Cu, Ga and Se systems, binary Cu–Se, Ga–Se systems and ternary Cu–Ga–Se system. The electrodeposition metallic Ga from Ga unitary electrolytes is impossible due to its low reduction potential. No reduction peak was found for the reduction of Ga3+ to Ga in the cyclic voltammogram of unitary system. However, in the cyclic voltammogram of ternary Cu–Ga–Se system, reduction peak at −0.6 V was observed with addition of GaCl3. Also, current density of the peak was increased with increasing concentration of GaCl3. It is corresponded to the formation of gallium selenides and/or copper–gallium–selenium compounds. The contents of Ga in the films were significantly changed from −0.4 V to −0.6 V. SEM and XRD analysis also showed that surface morphology and crystalline phase of films were significantly changed with increasing Ga content.

Investigation on the Effect of Complexing Agents and Concentrations on Electrodeposition of ZnS Film

Abstract. Electrodeposition of ZnS thin film is affected by many factors. The effects of experimental conditions and concentrations of complexing agents on the electrochemical properties of plating solution were investigated. Electrochemical workstation was used to test cyclic voltammetry curves in different situations. According to the oxidation and reduction peaks of the curves, the experimental results showed that the effect of complexing agent was the best, while the ammonia was worst. With the increase of concentration of sodium citrate, reduction peak shifted to the negative part, in the meanwhile plating solution with 30 mmol/L of sodium citrate was the best condition for electrodeposition of ZnS thin film.

Structural and magnetic properties of FeCoNi thin films

Structural, magnetic and surface morphology of electro-deposited thin films of FeCoNi were studied in this paper. X-ray diffraction analysis showed that FeCoNi thin films consisting of mixtures of bcc and fcc crystal structure were grown on Cu substrate. The grain size decreased with increase in current density. Magnetic studies revealed that as current density increased from 50 to 450 mA/cm2, coercivity decreased from 257 to 72 Oe and saturation magnetization increased from 6.58 to 88.85 emu/cm2 for in-plane magnetic field, while coercivity decreased 287–203 Oe and saturation magnetisation increased from 3.91 to 36.411 emu/cm2 for out of plane. Surface analysis by SEM showed porous nature of thin films as expected for ferromagnetic thin films.

Electrodeposition and Characterization of Hematite Films Obtained from DMSO Solution

The present study shows the results obtained in the electrodeposition of hematite thin films from DMSO solution employing FeCl3 and molecular oxygen as precursors. The films were obtained through a potential cycling program at different cathodic limits and at different electrolytic bath temperatures. In all cases, as-grown films were amorphous and photoelectrochemically inactive. An annealing procedure is necessary to completely transform the electrodeposited iron oxide to a-Fe2O3 phase. XRD analyses confirm the presence of diffraction peaks corresponding to hematite after annealing, showing a strong preferential orientation of the [110] axis vertical to the substrate. Different techniques (XRD techniques, XPS analyses, SEM images, UV-Vis spectroscopy, Mott-Schottky plots and photocurrent – potential curves) have been employed in order to characterize the films and determinate their properties according with the conditions of electrodeposition and the annealing temperature.

Room Temperature Electrodeposition of Molybdenum Sulfide for Catalytic and Photoluminescence Applications

An elegant method for the electrodeposition of MoS2 thin films using room temperature ionic liquids (RTIL) as an electrolyte was developed. Simple molecular precursors of Mo and S were added in different concentrations to tune the composition and deposition process. The electrodeposition of MoS2 was confirmed with both Raman spectroscopy and XPS. Analysis showed that the electrodeposited MoS2 films form a flower shape morphology with edge active sites that promote the hydrogen evolution reaction (HER). Furthermore, this technique enables selective tuning of the film thickness and demonstrates high photoluminescence activity with a decrease in the number of layers.

Electrodeposition and characterization of nano-structured black nickel thin films

The electrodeposition and characterization of nano-structured black nickel coatings were presented. The influences of bath pH, electrodeposition time, stirring speed, temperature and current density on the color and microstructure of the electrodeposited nickel film were investigated through naked eyes, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Meanwhile, the corrosion resistance of the optimized black nickel film was evaluated by the polarization measurement and electrochemical impedance spectroscopy (EIS) in the neutral 3.5% NaCl solution. The results show that the color of the electrodeposited nickel film was highly dependent on the above technological parameters. The operating parameters were optimized mainly according to the color. The optimized black nickel film possesses nano-structure with an average grain diameter of about 50 nm. It also exhibits enhanced corrosion resistance when compared with white nickel coatings electrdodeposited under the same condition except the variation of the electroplating current density.

Pulse electrodeposition of Prussian Blue thin films

The effects of pulse electrodeposition parameters like peak current density and frequency on the electrochemical properties of Prussian Blue thin films were investigated. Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Chronoamperometry tests were carried out on Prussian Blue thin films which were pulse electrodeposited on Indium Tin Oxide coated glass substrates. The results showed that increase in the peak current densities and using higher pulsating frequencies during electrodeposition decreases the charge transfer resistance of the thin films while the diffusion coefficient of electroactive species in the films is increased as a consequence of using the same pulsating parameters. In addition, pulse electrodeposition technique does not alter deposition mechanism and morphology of the Prussian Blue thin films.

Effects of Diammonium Citrate Concentration on Structural and Magnetic Properties of Nanostructured NiFeWS Alloy Thin Films

Electro-deposition of NiFeWS thin films was carried out from diammonium citrate bath at a constant current density (1 A/dm2 and controlled pH of 8 by varying the citrate bath concentration (0.2, 0.3, 0.4, 0.5 mol/lit). The surface morphology, microstructure and magnetic properties such as coercivity, saturation magnetization and magnetic flux density were investigated for electrodeposited NiFeWS soft magnetic thin films. The SEM micrographs of the electrodeposited films from the highly concentrated citrate bath (0.5 mol/lit) have no microcracks and also the films have more uniform surface morphology. The predominant peaks in X-ray diffraction pattern reveal the crystalline nature of the film and structure belonging to FCC. From the VSM results of the coated films, the various magnetic analysis such as coercivity, saturation magnetization and magnetic flux density were calculated. The hardness and adhesion of the electroplated films were also investigated. Reasons for variation in magnetic properties and structural characteristics were discussed.

Studies on antimony telluride thin films as buffer layer for solar cell applications

Antimony telluride (Sb2Te3) is binary p-type compound of narrow band gap (0.3 eV) semiconductor, which has application in solar cell to make low resistive ohmic contact. Sb2Te3 acts as a diffusion barrier and may improve the ohmic contact due to top doping on CdTe surface. We have synthesized antimony telluride thin films by electrodeposition technique and studied their various properties. Three-electrode system was employed for the electrodeposition of Sb2Te3 thin films on fluorine tin oxide coated glass substrates. Sb2O3 and TeO2 were used as an ionic source for Sb and Te ions, whereas tartaric acid was used as complexing agent and also supportive electrolyte. The electrochemical parameters were optimized by slow scan cyclic voltammetry (CV) experiment. The effects of deposition potential on morphology, structure, and composition have been studied. Various properties of Sb2Te3 film were studied by X-ray diffraction, atomic force microscopy (AFM), and energy dispersive X-ray analysis. Prominent (015) peak of Sb2Te3 was attributed at 2θ = 28.36° for as-deposited and heat treated samples. After heat treatment, crystallinity of the film was improved. The electrical properties of as-deposited and annealed films were studied by two probe method. Growth potential dependent I-V characteristics of FTO/Sb2Te3/Au diode were studied and found to be Schottky barrier diode. Compact, uniform, and void free films surface morphology is observed by AFM. The effect of deposition potentials on morphology, structure, and composition of Sb2Te3 thin films were studied.

Electrodeposition of ZnO Thin Films with Controllable Impurities and Microstructures

To enhance the conductivity and reduce the surface roughness of ZnO films, electrodeposition of ZnO films on the ITO substrate had been studied for the application of inverted organic solar cells. ZnO films with the grain size range from 0.4 to 2 μm had been fabricated by varying the temperature, ion concentration and deposition potentials. Moreover, ZnO films with the impurity energy level of 2.28±0.20 eV origin from the oxygen vacancy, had been found in the PL emission. It is found that as the applied potential went more negative, the concentration of the oxygen vacancies increased, and the emission peak of the impurity level had higher intensity. By changing the ion concentration and temperature of the electrolyte, the controllable microstructure and impurity levels of ZnO thin films had been achieved.

Electrodeposition and characterization of magnetostrictive galfenol (FeGa) thin films for use in microelectromechanical systems

In this paper, we investigate the challenges related to electrodeposition and characterization of magnetostrictive galfenol thin films as well as techniques used to overcome these issues. Successful deposition and evaluation of galfenol thin films is necessary for the design of galfenol based microelectromechanical devices. Stress is a primary concern because thick films and poor adhesion to substrates (e.g., silicon oxide) can lead to delamination and peeling. In addition, magnetostriction measurements require films that are uniform in thickness and composition over the sample area. Various adhesion layers were tested, and delamination was eliminated with Cr/Cu, which provided robust adhesion to the glass substrates used in capacitance bridge measurements. Uniformity and composition were controlled by the use of a rotating disk electrode for electrodeposition, which created a uniform boundary condition across the sample during deposition. The capacitance bridge technique was calibrated with Ni/glass samples, after which a magnetostriction of 140 ppm was measured for Fe83Ga17 films. These results represent the first magnetostriction measurements of electrodeposited galfenol.