Electrodeposition Of Thin Films Research Articles

Electrodeposition of Lithium Anode Thin Films and Its Application in All-Solid-State Microbatteries

Thin film all-solid-state secondary microbatteries are extensively studied since the 1990’s [1-3]. These systems present specific features such as reduced surface, high thermal resistance, excellent cycle life, absence of liquid electrolyte, etc. that make them the most suitable energy sources for some emerging applications (real time clock, medical implants, secured smart cards, etc.). All-solid-state microbatteries are realized by successive deposition of thin films with a total thickness of less than 20 µm. The corresponding manufacturing steps are mainly carried out using physical vapor deposition processes such as thermal evaporation or sputtering, which are commonly used in the microelectronics industry. Each deposited layer is patterned either with shadow mask or photo-lithography step. Shadow masking process involves restrictive steps such as mask alignment and cleaning. Moreover, standard photolithography processes, commonly used in the microelectronics industry, are actually difficult to adapt to microbattery systems considering the high reactivity of active materials, mainly lithium metal and lithiated compounds like LiPON. The use of such techniques, for deposition as well as patterning steps, involves sophisticated equipment leading to high production and maintenance costs. Furthermore, deposition rates of each processing step remains rather low (~ 10 nm mn-1 for sputtering techniques). In this study, to increase throughput and limit production costs, Lithium anode thin films are deposited via an easy electrochemical route [4-5] using standard carbonate based electrolyte with LiPF6 salt. Deposited films exhibit self-aligned nanorods structure without any dendritic growth. The electrochemical performance of such lithium electrodes is evaluated in coin cell configuration versus silicon thin films and no obvious difference in behavior is observed between electrodeposited lithium thin films and bulk lithium metal foils. The process is then used to manufacture all-solid-state thin film battery stacks. The lithium anode electrodeposition on non-conductive LiPON layer is possible through the use of very thin Cu layer (Fig1). The all solid state micro-battery stack is then composed of a silicon cathode, LiPON as solid electrolyte, copper as conductive layer for the electrodeposition process and electrodeposited lithium as anode material (Fig2). Finally, the electrochemical performance (cycle life, specific capacity and curve shape (Fig3)) is close to those obtained with standard evaporated lithium (without Cu layer). This new lithium film deposition technique is suitable for 3D textured or high roughness substrates and limited to electronic conductive surfaces. In the end, this enables a direct patterning of the lithium anode layer. Therefore, considering that all other microbattery materials can be structured by photolithography, the Li electrodeposition could avoid using shadow masking technique during the all-solid state microbatteries manufacturing process. The authors thank ST-Microelectronics and the French Directorate General for Enterprise (DGE) for financial support through the Tours2015 project. [1] J.B. Bates, N.J. Dudney, D.C. Lubben, G.R. Gruzalski, B.S. Kwak, X. Yu, R.A. Zuhr, J. Power Sources 1995, 54,58-62. [2] J.B. Bates, N.J. Dudney, B. Neudecker, A. Ueda, C.D. Evans, Solid State Ionics 2000, 135,33-45. [3] B. Fleutot, B. Pecquenard, F. Le Cras, B. Delis, H. Martinez, L. Dupont, D. Guy-Bouyssou, J. Power Sources 2011, 196,10289-10296. [4] X. Yang, Z. Wen, X. Zhu, S. Huang, Solid State Ionics 2005, 176,1051-1055. [5] J. Qian, W. Xu, P. Bhattacharya, M. Engelhard, W.A. Henderson, Y. Zhang, J.-G. Zhang, Nano Energy 2015, 15,135-144. Figure 1

Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films.

Single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu2O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiOx layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu2O follow the out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu2O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the -24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu2O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.

Efficient electrochemical treatment based on electrodeposited thin films of birnessite for mineralisation of AMPA (aminomethylphosphonic acid) in very soft conditions

The presence of AMPA in environment becomes today a real problem due to its persistence, its toxicity, and its multiple origins (main metabolite of glyphosate, the pesticide the most used in the world; degradation product of personal care and industrial products). This paper reports the development of a simple, effective, cheap and easy electrochemical treatment, for mineralising AMPA under very soft conditions: at room temperature, at free pH, and in a classical open electrochemical cell. The electrode material used is an electrodeposited thin film of birnessite, a non-toxic material, synthesised in very soft conditions. The original idea is to couple the spontaneous oxidative properties of birnessite to an electrochemical oxidation treatment in the aim to increase its reactivity towards this pollutant. Very good mineralisation rates and capacity (≈0.115g AMPA mineralized by gramme of birnessite) were obtained with very low energy supplies (Q≈3C). Some tests performed with concentrated glyphosate solutions, one of its main parents, give also good results allowing us to envisage the development of an easy method of wastewater treatments at very low costs in complement of classical methods and/or directly at the source of pollution.

One-step electrodeposition for targeted off-stoichiometry Cu2ZnSnS4 thin films

Cu2ZnSnS4 (CZTS) is a promising quaternary compound suitable for absorber layer of thin film solar cells. The precise control of the atomic ratio of the films are difficult for the electrodeposition of CZTS thin films. Here, we reported targeted off-stoichiometry CZTS thin films synthesized by one-step electrodeposition. We obtained Cu-poor thin films and the chemical composition of the as-deposited thin films were tailored to targeted off-stoichiometry. Based on the different kinetics of the metallic ion reduction, we successfully controlled the chemical composition by varying deposition time. After annealing, pure kesterite structure was obtained and the electronic interactions between Cu and Sn was verified in the films, which contributes to high carrier mobility. The band gap of the thin films were in the range of 1.43–1.52eV, which is suitable for absorber layers of thin film solar cells. The carrier mobility reached a value of 28.20cm2/Vs with carrier concentration of 2.09×1018cm−3 when Cu/(Zn+Sn) and Zn/Sn ratios were 0.97 and 1.13, respectively. This work paves a way for synthesizing targeted off-stoichiometry compounds by controlling kinetics and reaction time in large scale.

Potentiostatic electrodeposition of nanostructured NiO thin films for their application as electrocatalyst

We report the synthesis of nanostructured nickel oxide (NiO) films, and their implementation as photocathodes in photoelectrochemical (PEC) cells for hydrogen generation by water splitting. NiO nanograins were prepared by electrodeposition of nickel from complexing glycinate solution at different pH from 2 to 13, followed by annealing at 400°C. The characterization of NiO films was carried out by XRD, SEM, UV–vis, PL and electrochemical techniques. XRD study showed that NiO with cubic structure was obtained for all films. SEM micrographs showed a spherical-granular structure for NiO films with a grain size between 400 and 125nm. The measurements carried out on PEC cell with NiO as photocathodes, under simulated solar irradiation, demonstrated a significant increase of cathodic photocurrent as the pH of electrodeposition solution was increased. Analysis of Mott-Schottky plots for each NiO film showed a remarkable increment of the charge carrier density as the grain size was decreasing.

Ultramicroelectrode Studies of Self-Terminated Electrodeposited Ultrathin Ni Electrocatalysts

Metal hydroxides, oxides, and related compounds, particularly those containing Ni and Fe, have received much attention for oxygen evolution reaction (OER) catalysts because they have produced some of the highest reported OER rates and are chemically stability in alkaline media. Electrode platforms based on Ni and Fe are attractive because they exclude expensive precious metals, and thin films of these metals can be coupled with light-absorbing materials in photoelectrochemical energy conversion devices used in water electrolysis. Our group has been investigating growth of thin metal films through self-terminated deposition reactions, i.e., wet atomic layer deposition. These reactions can be coupled with potential modulation to deposit films of any desired thickness [1]. Similarly, self-termination behavior has been recently uncovered for iron-group metals albeit through a different mechanism than that reported for Pt. Ni growth stops upon the onset of H2O reduction whereas formation of a saturated Hupd monolayer is responsible for termination of Pt deposition. Possible explanations for Ni growth termination include formation of a passivating surface-bound OH– species formed upon H2O reduction or cross reactions between the egress of OH– and the incoming Ni2+ species to form Ni(OH)2 and related products. Here, we employed ultramicroelectrodes (UME’s) and scanning electrochemical microscopy (SECM) to further probe electrodeposition of thin metal films of Ni on Au electrodes and elucidate possible mechanisms for self-termination. Benefits of using UME’s include minimized solution resistance and well-controlled mass transport. Voltammetry of Au UME’s in electrolytes containing Ni2+ revealed a sharp, current spike at the onset of H2O reduction, demonstrating the first observed electrochemical signal corresponding to a metal self-termination process. The sharpness of this feature is reminiscent of a phase change or the initiation of a catalytic process. One explanation is that a highly-active species for the HER is generated upon H2O reduction in the presence of Ni2+; it is well-known that hydroxy-nickel species form during Ni2+ reduction due to a rise in pH, and Ni(OH)2catalyzes the HER. Generation/collection SECM, where a second Pt UME was used as the collector electrode, indicated that H2is generated during the process giving rise to this cathodic spike. Electrochemical results will be compared with optical characterization as well as SEM, EDX, and Raman spectroscopy to characterize electrodeposited films. Ni films deposited with only concurrent proton reduction were silvery, bright, and continuous; however, at potentials near the onset of H2O reduction, the Au was covered with a patchy, thin metallic film. These results agree with those at larger, cm-sized electrodes. At sufficiently negative potentials under H2O reduction, a thick, dull gray ring formed on the glass sheath surrounding the Au disk electrode, suggesting a transport-dependent phenomenon in the diffusion layer, e.g., precipitation of hydroxy-nickel species, surrounding the UME disk. At even higher overpotentials, hydrogen bubbles formed, destroying the Ni films. [1] Y. Liu et al,. Science, 338, 1327 (2012) N.L.R. acknowledges a National Research Council (NRC) Postdoctoral Research Assistantship.

Electrodeposition and Capacitance of WS2 Thin Films Onto ITO and Glassy Carbon from Aqueous and Non-Aqueous Electrolytes

Two-dimensional (2D) layered materials, including graphene, metal oxides, metal chalcogenides and their composites have shown to be efficient and promising materials for high performance supercapacitor electrodes, with high surface area and large in-plane conductivity. Among the 2D layered supercapacitors, MoS2, MoSe2, WS2, and WSe2 are semiconductors with intriguing electronic, electrochemical and electrocatalytic properties. We have synthesized WS2 thin films onto both ITO and glassy carbon electrodes by the electro-reduction of (NH4)2WS4 from both aqueous and acetonitrile electrolytes. During cyclic voltammetry, a cathodic peak that overlaps with H2 evolution is observed at at -1.2V vs Ag/AgCl in aqueous solutions. In acetonitrile, no cathodic peak is observed on ITO, but a cathodic peak that overlaps with a background cathodic peak is observed on glassy carbon. The background peak appears to arise form TEA-BF4 reduction, since the current density scales with TEA-BF4 concentration. The standard reduction potential, effective diffusion coefficient and transfer coefficient for WS2 electrodeposition in acetonitrile are determined are estimated from cyclic voltammetry at different scan rates. Results will also be presented for the specific capacitance of WS2 films deposited atop glassy carbon electrodes (GCE) following application of potential sweep methods for activing GCE.

Electrodeposition of ZnO thin films on conducting flexible substrates

In this work, we studied the DC electrochemical deposition of zinc oxide (ZnO) thin films on a conducting and flexible substrate, for their application in energy harvesting piezoelectric nanodevices. The deposition process was performed by varying the zinc nitrate concentration (c) in the electrolyte, its temperature (T), and the applied deposition potential (V), and subsequently tracing the influence of such parameters on the morphology (analyzed by scanning electron microscopy), crystallography (X-ray diffraction), and thickness (using the deposition current transient curves) of the ZnO thin films. The variation of the electrodeposition parameters led to the formation of different micro- and nano-structures, such as flat layers, microflowers, nanospheres, webs, and microramifications. Furthermore, the analysis of the deposited charge (by integrating the deposition current transients) illustrated an increase in the deposition rate with the increase of T and c, and a decrease of V. Finally, the maximum ZnO film thickness (~5 \(\upmu {\mathrm{m}}\)) was obtained for T = 80 °C, c = 0.1 M, and V = −1.5 V. This study provides us important tools to tune the electrochemical growth of ZnO thin films.

Electrodeposition and characterisation of CdS thin films using thiourea precursor for application in solar cells

CdS thin films have been successfully electrodeposited on glass/FTO substrates using acidic and aqueous solution of CdCl2.xH2O and thiourea (SC(NH2)2). The electrodeposition of CdS thin films were carried out potentiostatically using a 2-electrode system. The prepared films were characterised using X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, Atomic force microscopy, Photoelectrochemical cell measurements, Electrical resistivity measurements and UV–Vis spectrophotometry to study their structural, compositional, morphological, electrical and optical properties, respectively. The structural studies show that the as-deposited and annealed CdS layers are polycrystalline with hexagonal crystal structure and preferentially oriented along (200) planes. The optical studies indicate that the ED-CdS layers have direct bandgaps in the range (2.53–2.58) eV for the as-deposited and (2.42–2.48) eV after annealing at 400 °C for 20 min in air. The morphological studies show the good coverage of the FTO surface by the CdS grains. The average grain sizes for the as-deposited and annealed layers were in the range ∼(60–225) nm. These grains or clusters are made out of smaller nano crystallites with the sizes in the range ~(11–33) nm. The electrical resistivity shows reduction as thickness increases. The resistivity values for the as-deposited and annealed layers were in the range (0.82–4.92) × 105 Ωcm. The optimum growth voltage for the CdS thin films was found to be at the cathodic potential of 797 mV with respect to the graphite anode. No visible precipitations of elemental S or CdS particles were observed in the deposition electrolyte showing a stable bath using thiourea during the growth.

Electrodeposition of lithium metal thin films and its application in all-solid-state microbatteries

Lithium metal thin films are deposited via an easy electrochemical route using standard carbonate based electrolyte with LiPF6 salt. Deposited films exhibit self-aligned nanorods structure without any dendritic growth. The electrochemical performance of such lithium electrodes is evaluated in coin cell configuration versus silicon thin films and no obvious difference in behavior is observed between electrodeposited lithium thin films and bulk lithium metal foils. The process is then used to manufacture all-solid-state thin film battery stacks composed of a silicon cathode, LiPON as solid electrolyte, copper as conductive layer for the electrodeposition process and electrodeposited lithium as anode material. Finally, the electrochemical performance (cycle life, specific capacity and curve shape) is close to those obtained with standard evaporated lithium. This new lithium film deposition technique is suitable for 3D textured or high roughness substrates and limited to electronic conductive surfaces. In the end, this enables a direct patterning of the lithium anode layer. Therefore, considering that all other microbattery materials can be structured by photolithography, the Li electrodeposition could avoid using shadow masking technique during the all-solid state microbatteries manufacturing process.

Electrodeposition of Fe₃O₄ Thin Film and Its Application as Anode for Lithium Ion Batteries.

Fe₃O₄ films were prepared by electrodeposition under varying preparation conditions (current density, temperature, and time). The electrodeposited Fe₃O₄ were characterized in terms of morphology and composition using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrodeposited films were also tested as anode in coin cell systems. Fluoroethylene carbonate (FEC) electrolyte was found to improve the battery performance due to formation of a better solid electrolyte interface (SEI). Conducting polymer of polypyrrole (PPY) was coated on the surface of Fe₃O₄ films for the first time with the aim to improve the electric conductivity and to buffer volume expansion of Fe₃O₄ films.

Investigation of Annealing Conditions on Electrochemically Deposited CZTS Film on Flexible Molybdenum Foil

In this work, the electrodeposition of Cu2ZnSnS4 thin films on molybdenum thin foil was reported. In order to guarantee co-deposition of elements with different standard electrochemical potential, an aqueous electrolyte added with ligand agents was used. I addition, deposition parameters were carefully chosen, in order to ensure good quality and suitable composition of the films. The deposited films were sulfurized in controlled atmosphere at 580°C, scrutinizing the influence of the annealing conditions on the features of the films. Structure, morphology and composition were investigated by XRD SEM, EDS and Raman spectroscopy. Results reveal the growth of good quality films, with a uniform morphology and chemical composition suitable for solar cell application.

Role of p-Hydroxybenzhydrazide Additive in Electrodeposition of Thin NiP Film Used as a Nonmagnetic Spacer in Laminated (CoFe/NiP) Nano Structures

Electrodeposition of NiP film used as a thin nanomagneic spacer in laminated multilayer (2.4T CoFe/NiP) n perpendicular writer pole for recording magnetic heads is described. The electrodeposition of laminated multilayers was carried out in a dual-bath automated electroplating tool. The thin NiP films with thickness from 2 to 5 nm were obtained as nonmagnetic amorphous NiP alloys with P-content higher than 18 at. %. The problem of composition gradient at the CoFe/NiP interface was solved by using a p-hydroxybenzhydrazide organic additive in the plating solution. The details of the electrodeposition of NiP films, the role of p-HBHy and properties of electrodeposited NiP films and CoFe/NiP multilayers are discussed.

Enhancement of Water Oxidation Photocurrent for Hematite Thin Films Electrodeposited with Polyvinylpyrrolidone

Hematite photoanodes were prepared by anodic electrodeposition in the presence of polyvinylpyrrolidone (PVP). PVP has been shown to alter hematite nanoparticle morphology, but has not been used before for anodic electrodeposition of thin films. Significant improvement in the water oxidation photocurrent was observed with PVP, with greater charge-collection efficiency due to a finer nanostructured morphology, and higher quantum yields for photons absorbed throughout the thickness of the hematite film from its increased porosity. Different post-deposition treatments showed distinct effects with and without PVP. Compared to electrodes dried 48 hours before annealing under N2, electrode performance was significantly reduced upon annealing in air, or annealing immediately after deposition when PVP was not used. A distinct wavelength dependence for front- versus back-side illumination, and a ∼100-fold decrease in dopant density, was attributed to formation of a dead layer on the top of those electrodes with reduced photoactivity, and was avoided using PVP.

Triethanolamine-facilitated one-step electrodeposition of CuAlSe2 thin films and the mechanistic studies utilizing cyclic voltammetry

Abstract The electrochemical behavior of the compositional ingredients CuCl 2 , AlCl 3 and SeO 2 individually or collectively in acidic aqueous solution was investigated on a glassy carbon electrode using the technique of cyclic voltammetry. Co-electrodeposition mechanism of CuAlSe 2 was attempted to be unraveled through cyclic voltammetric study of the electroactive species. The formation of CuAlSe 2 was found to be achieved by the generation of the compounds Al 2 Se 3 and Cu 2 Se via reductions and/or chemical reactions of the precursors. Triethanolamine as the complexing agent was introduced in the electrodeposition of CuAlSe 2 on indium doped tin oxide glass substrates in order to assist the deposition and the stoichiometric composition of CuAlSe 2 thin films was fabricated. The deposited thin films were characterized by X-ray diffraction, scanning electron microscopy, UV–Vis spectrometry, Auger electron spectroscopy and energy dispersive X-ray spectrometry analysis.

Ground nut seed like hydrophilic polypyrrole based thin film as a supercapacitor electrode

The paper reports the electrodeposition of polypyrrole thin film by galvanostatic mode of deposition. The structural study of polypyrrole film is characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy. The surface morphological study is carried out with scanning electron microscope (SEM) techniques. The XRD and FTIR spectroscopy study shows the formation of amorphous and conducting polypyrrole thin film. SEM images shows that the substrates are uniformly coated with polypyrrole thin films. The surface wettability study is carried out by means of contact angle measurement. Surface wettability study shows that the films are hydrophilic in nature. The testing of polypyrrole film electrode as a supercapacitor is made with the help of cyclic voltammetry, galvanostatic charge–discharge measurement and electrochemical impedance spectroscopy study. The value of specific capacitance was found to be 381 F g−1 in 0.5 M Na2SO4 aqueous solution at scan rate 5 mV s−1 in the −1.0 to +1.0 V versus saturated calomel electrode. However, the value of Coulombic efficiency, specific energy and specific power of polypyrrole thin film electrode is observed to be 96.54 %, 762.60 Wh kg−1 and 281,000 kW kg−1.

Fabrication and characterization of flexible solar cell from electrodeposited Cu2O thin film on plastic substrate

We present here for the first time the fabracition of a p-Cu2O/ZnO/AZO flexible heterojunction solar cell by electrodeposition of Cu2O thin film on a plastic substrate and sputtering of ZnO:Al layer. The Atomic Layer Deposition (ALD) has been employed to insert 5nm ZnO as buffer layer. The heterojunction solar cell was characterized by Raman spectroscopy and scanning electron microscopy that show pyramidal shape and phonon modes for Cu2O thin film. Current–voltage (J–V), capacitance–voltage (C–V) and the external quantum efficiency (EQE) measurements were performed to understand the heterojunction properties. The solar cell device exhibits a power conversion efficiency of 0.897±0.005% with an open circuit voltage of Voc=300mV, a short circuit current density of Jsc=6.819±0.048mAcm−2 and a fill factor of FF=0.439±0.006. The values of the built-in potential and the acceptor concentration at the junction were estimated from the reverse bias C–V measurement to be 0.37V and 6.67×1016cm−3, respectively.

Electrodeposition of Sm-Fe Thin Film in Aqueous Solution under a High Magnetic Field

Electrodeposition of Sm-Fe Thin Film in Aqueous Solution under a High Magnetic Field

A review of electroplating for V–VI thermoelectric films: from synthesis to device integration

Abstract

Electrodeposition of Bi2Te3 thin films onto FTO substrates from DMSO solution

Electrodeposition of Bi2Te3 thin films onto FTO substrates from DMSO solution