Acetate Bath Research Articles

Electrical Resistivity Modification of Electrodeposited Mo and Mo–Co Nanowires for Interconnect Applications

Achieving historically anticipated improvement in the performance of integrated circuits is challenging, due to the increasing cost and complexity of the required technologies with each new generation. To overcome this limitation, the exploration and development of novel interconnect materials and processes are highly desirable in the microelectronics field. Molybdenum (Mo) is attracting attention as an advanced interconnect material due to its small resistivity size effect and high cohesive energy; however, effective processing methods for such materials have not been widely investigated. Here, we investigate the electrochemical behavior of ions in the confined nanopores that affect the electrical properties and microstructures of nanoscale Mo and Mo–Co alloys prepared via template-assisted electrodeposition. Additives in an electrolyte allow the deposition of extremely pure metal materials, due to their interaction with metal ions and nanopores. In this study, boric acid and tetrabutylammonium bisulfate (TBA) were added to an acetate bath to inhibit the hydrogen evolution reaction. TBA accelerated the reduction of Mo at the surface by inducing surface conduction on the nanopores. Metallic Mo nanowires with a 130 nm diameter synthesized through high-aspect-ratio nanopore engineering exhibited a resistivity of (63.0 ± 17.9) μΩ·cm. We also evaluated the resistivities of Mo–Co alloy nanowires at various compositions toward replacing irreducible conventional barrier/liner layers. An intermetallic compound formed at a Mo composition of 28.6 at%, the resistivity of the Mo–Co nanowire was (58.0 ± 10.6) μΩ·cm, indicating its superior electrical and adhesive properties in comparison with those of conventional barriers such as TaN and TiN. Furthermore, density functional theory and non-equilibrium Green’s function calculations confirmed that the vertical resistance of the via structure constructed from Mo-based materials was 21% lower than that of a conventional Cu/Ta/TaN structure.

Substrate Effect on Liquid Petroleum Gas Sensors of Cuprous Oxide Thin Films Electrodeposited in Acetate Bath

Cuprous oxide thin films were electrodeposited in an acetate bath (∼60 °C) using FTO, ITO, Ti, and Cu substrates to understand their influence on the surface morphology of the films and their wetting nature against Liquid Petroleum gas (LPG). According to spectral response and capacitance-voltage analysis, n-Cu2O films resulted in the electrodeposition bath at pH range of 5.7–6.5. In addition, SEM data revealed the substrate effect on crystal morphologies of Cu2O thin films with unique porous and tetrahedron structures of Cu2O having different grain sizes. XRD analysis gives evidence in support of these grain size variation which emphasized Ti and ITO to have the lowest grain sizes of 24 nm and 30.9 nm respectively. Following the contact angle measurements and their wetting natures, characterized films were subjected to LP gas sensing evaluations in which, proved that deposited n-Cu2O films on FTO, ITO, and Ti can improve gas sensor performances with their moderate wetting behaviors. Under stable sensing conditions, ITO exhibits the most enhanced LPG response, recovery, and stability over time. In comparison, all the experimental results unveiled that substrates do have a major effect, in optimizing interface properties of Cu2O films to achieve better response in many fields of applications.

Effect of Temperature on Electrochemically Assisted Deposition and Bioactivity of CaP Coatings on CpTi Grade 4.

Calcium phosphate (CaP) coatings are able to improve the osseointegration process due to their chemical composition similar to that of bone tissues. Among the methods of producing CaP coatings, the electrochemically assisted deposition (ECAD) is particularly important due to high repeatability and the possibility of deposition at room temperature and neutral pH, which allows for the co-deposition of inorganic and organic components. In this work, the ECAD of CaP coatings from an acetate bath with a Ca:P ratio of 1.67, was developed. The effect of the ECAD conditions on CaP coatings deposited on commercially pure titanium grade 4 (CpTi G4) subjected to sandblasting and autoclaving was presented. The physicochemical characteristics of the ECAD-derived coatings was carried out using SEM, EDS, FTIR, 2D roughness profiles, and amplitude sensitive eddy current method. It was showed that amorphous calcium phosphate (ACP) coatings can be obtained at a potential −1.5 to −10 V for 10 to 60 min at 20 to 70 °C. The thickness and surface roughness of the ACP coatings were an increasing function of potential, time, and temperature. The obtained ACP coatings are a precursor in the process of apatite formation in a simulated body fluid. The optimal ACP coating for use in dentistry was deposited at a potential of −3 V for 30 min at 20 °C.

Reduction-Induced Synthesis of Reduced Graphene Oxide-Wrapped Cu2O/Cu Nanoparticles for Photodegradation of Methylene Blue

A photocatalytic composite in powder form having nanosized Cu2O/Cu granules wrapped in multilayered reduced graphene oxide (rGO) sheets was synthesized. The fabrication process was initiated by potentiostatic electrodeposition of n-type Cu2O thin films on Ti substrates in an acetate bath. Peeled-off Cu2O thin films were next subjected to ultrasonic mixing with graphene oxide (GO) by maintaining a Cu2O/GO mass ratio of 125:10. Chemical reduction using ascorbic acid converted Cu2O partially to Cu, while converting GO completely to rGO as confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Transmission electron microscopy (TEM) images of the composite confirmed the presence of Cu nanoparticles of the size of tens of nanometers within the photocatalyst, Cu2O. The fabrication process therefore implicitly favors synthesis of nanosized Cu playing the role of a co-catalyst. The Cu2O/Cu/rGO composite showed significantly higher ability to degrade methylene blue in solution, while the effects due to photocorrosion were minimal during a month of testing when compared with Cu2O alone. The layered rGO provides an effective medium for transporting photoelectrons to the reactant while inhibiting photocorrosion. Furthermore, the composite demonstrated its ability to split water under visible light in the presence of methanol and creates a promising platform to further develop a variety of other photocatalytic applications.

Long-Term Assessment of the In Vitro Corrosion Resistance of Biomimetic ACP Coatings Electrodeposited from an Acetate Bath.

Calcium phosphate coatings are able to improve the osseointegration process due to their chemical composition, which is similar to that of bone tissues. In this work, to increase the long-term corrosion resistance and to improve the osseointegration process of commercially pure titanium Grade 4 (CpTi G4), biomimetic amorphous calcium phosphate (ACP) coatings were electrodeposited for the first time from an acetate bath with a pH level of 7.0 and a Ca:P ratio of 1.67. ACP coatings were obtained on CpTi G4 substrate subjected to sandblasting and autoclaving using electrochemically assisted deposition at a potential of −3 V relative to the open circuit potential for 30 min at room temperature. SEM, EDS, 2D roughness profiles, amplitude-sensitive eddy current method, and Kelvin scanning probe were used for the surface characterization of the biomaterial under study. In vitro corrosion resistance tests were conducted for 21 days in artificial saliva using open circuit potential, polarization curves, and electrochemical impedance spectroscopy measurements. The passive-transpassive behavior was revealed for the obtained ACP coatings. The long-term corrosion resistance test showed a deterioration of the protective properties for CpTi G4 uncoated and coated with ACP with immersion time. The mechanism and kinetics of the pitting corrosion on the CpTi G4|TiO2|ACP coating system are discussed in detail.

(General Student Poster Session Winner - 2nd Place) Molybdenum Electroplating Using Concentrated Chloride Aqueous Solution

Molybdenum (Mo) is a metal that has excellent wear resistance and high-temperature strength, and is used in various fields such as aircraft and automotive industries. Since Mo is difficult to be molded due to its high melting point (2625 °C), Mo coating techniques are of interest and importance. We focused on electroplating from a concentrated aqueous solution in search of a process that can replace conventional processes such as chemical vapor deposition (CVD) and sputtering, which require high temperature or vacuum equipment. It has been believed that metallic Mo cannot be obtained by electrodeposition from aqueous solutions, although it can be co-deposited with Fe-group elements. Recently, there has been several reports on the electrodeposition of metallic Mo from a concentrated acetate aqueous solution, aiming for suppressing hydrogen generation reaction during electrodeposition [1]. In this study, we worked on Mo electroplating from concentrated chloride aqueous solutions: they enabled chromium electrodeposition using Cr3+ ion without additional chelating agents [2].First, a concentrated aqueous solution of 11.1 mol kg–1 LiCl was prepared. Then, as Mo source, 1.0 mol kg–1 of MoCl5 or 0.0014 mol kg–1 of (NH4)6Mo7O24 were dissolved to prepare the bath. Electrochemical measurements were performed at room temperature in air. A brass plate with a matte Ni plating was used as a working electrode. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), and potentiostatic electrodeposition were performed. The composition and surface morphology of the obtained electrodeposits were investigated by SEM-EDX, XRD and XPS.The results of LSV and CV show that the reduction current decreased as bulk LiCl concentration increases, evidencing that the generation of hydrogen is suppressed. Fig. 1(a) shows the surface SEM image of a sample obtained by potentiostatic electrodeposition from the LiCl–MoCl5 bath. Spherical deposits of several micrometers were observed, and EDX analysis revealed that the main component was Mo and O. Such behaviors were also observed in the case of the LiCl–(NH4)6Mo7O24 bath. It is suggested that the Mo source and Mo concentration do not so much affect the surface morphology. Fig. 1(b) shows the XRD patterns of a sample, in which a weak peak appeared at a diffraction angle of 40.5°. The peak corresponds to 110 diffraction of Mo, indicating that the phase composed of nanocrystals. A heat treatment of the sample at 800°C for 30 min in vacuum gave a highly crystalline sample with the conventional bcc structure of metallic Mo. XPS analysis detected metallic Mo in the sample after sputtered by Ar+ ion.In conclusion, we succeeded in electrodepositing metallic Mo from a concentrated chloride aqueous solution for the first time. It showed that hydrogen generation reaction during electrodeposition, which is a current problem, can be suppressed by coordinating and stabilizing many water molecules around ions. Therefore, the use of concentrated aqueous solution may play a key role in Mo electroplating. The deposits contained considerable oxygen impurities, as is the case of acetate bath [1]. Further studies on additives are required.

XPS studies on the Mo oxide-based coatings electrodeposited from highly saturated acetate bath

The possibility to use highly saturated acetate bath to electrodeposit the mixed-phase materials containing Mo oxides has been investigated. The XRD characterization revealed that the as-deposited coatings are amorphous and consist only of MoO2 and MoO3 phases without traces of metallic Mo phase. This statement has been supported by XPS measurements, which reveal the presence of three different molybdenum oxidations states in electrodeposits: Mo4+, Mo5+ and Mo6+. It was found that the Mo6+ state prevails with 41% of total contribution, whilst Mo5+ and Mo4+ contribute to 28 and 31%, respectively. The deposits retain an amorphous structure up to 800°C; while molybdenum at this temperature is predominantly oxidized to the Mo6+ state (91%). These results, coupled to those of SEM and EDS, revealed that concentrated acetate bath could be used mainly for the formation of the mixed valence molybdenum oxide film unlike to the deposition of the metallic Mo phase.

Photoelectrochemical study of electrochemically synthesized CdTe thin films from acetate-anion based ionic liquid bath

Potentiostatic deposition of CdTe thin films from acetate-anion based ionic liquid, 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]) bath has been carried out at 90 °C. A molar concentration ratio i.e. molar Cd/Te = 2 has been taken to electrochemically synthesize CdTe films under different dynamic conditions. FE-SEM showed the formation of homogeneous CdTe films over fluorine doped tin oxide (FTO) substrates. EDX revealed the formation of nearly stoichiometric CdTe films at optimal stirring rate of ∼400 rpm. The optical band gap of ∼1.45eV were observed with cubic zinc blende CdTe structure. XRD, RAMAN and XPS analysis confirmed the formation of pure CdTe phase with ultra-thin oxide over-layer. Photoelectrochemical studies of CdTe photoelectrodes prepared by electrodeposition technique was investigated in K2Sx and KH2PO4. Mott-Schottky analysis demonstrated the formation of p-CdTe with a flatband (Vfb) potential of ∼0.95VRHE. A high photocurrent density of 1.23 mA/cm2 has been achieved with solar conversion efficiency (ηc) of 1.50% for the pristine electrodeposited CdTe/FTO photocathode i.e. without surface modification, under chopped monochromatic illumination. This illustrates that the prepared CdTe photocathode can be a promising semiconductor candidate for application in photoelectrochemical hydrogen evolution from water. The use of acetate-anion based IL bath always resulted in p-type CdTe thin films.

Electrodeposition of Composite Ni-TiO2 Coatings from Aqueous Acetate Baths

In this paper, results concerning electrochemical deposition of Ni-TiO2 composite coatings are presented. The influence of electrode potential, concentration of TiO2 in the electrolyte, as well as the influence of magnetohydrodynamic effect (MHD) on deposition rate, composition, current efficiency, structure, surface states, and coatings surface morphology is described. Electrochemical studies were preceded by thermodynamic analysis of the system. In addition, the electrokinetic potential (ZP) of TiO2 particles in applied electrolyte was determined. Electrodeposited composites contained up to 2.15 wt. pct of TiO2. Depending on the applied electrolysis conditions, the current efficiency recorded up to 31.7 pct for B = 0 T and up to 34.2 for B = 1 T. Electrochemical studies as well as further material characterizations indicated the strong influence of the magnetic field on processes taking place at the electrode surface. Several results indicated that the synthesis process is accompanied by precipitation of nickel hydroxides and nickel hydrides as well as by hydrogen evolution reaction (HER). The obtained coatings were also characterized in order to determine their photoelectrochemical properties.

Design of Highly Active Electrodes for Hydrogen Evolution Reaction Based on Mo-Rich Alloys Electrodeposited from Ammonium Acetate Bath

The given research was driven by prospects to design Mo-rich coatings with iron group metals electrodeposited from a highly saturated ammonium acetate bath. The obtained coatings could be employed as prominent electrodes for the hydrogen evolution reaction (HER). It was found that the Mo content in Ni–Mo alloys can be tuned from 30 to 78 at.% by decreasing the molar ratio [Ni(II)]:[Mo(VI)] in the electrolyte from 1.0 to 0.25 and increasing the cathodic current density from 30 to 100 mA/cm2. However, dense cracks and pits are formed due to hydrogen evolution at high current densities and that diminishes the catalytic activity of the coating for HER. Accordingly, smoother and crack-free Ni–54 at.% Mo, Co–52 at.% Mo and Fe–54 at.% Mo alloys have been prepared at 30 mA/cm2. Their catalytic behavior for HER has been investigated in a 30 wt.% NaOH solution at temperatures ranging from 25 to 65 °C. A significant improvement of electrocatalytic activity with increasing bath temperature was noticed. The results showed that the sequence of electrocatalytic activity in alkaline media decreases in the following order: Co–52 at.% Mo > Ni–54 at.% Mo > Fe–54 at.% Mo. These peculiarities might be linked with different catalytic behavior of formed intermetallics (and active sites) in electrodeposited alloys. The designed electrodeposited Mo-rich alloys have a higher catalytic activity than Mo and Pt cast metals.

Effect of Bath pH on Electronic and Morphological Properties of Electrodeposited Cu2O Thin Films

The ability to systematically vary the flatband potential and the band edge positions of Cu2O by varying the deposition bath pH is considered important in the context of using Cu2O for photocatalytic water splitting. Capacitance-voltage (C-V) and dark and light current-voltage measurements were taken in order to investigate the electronic properties of electrodeposited Cu2O thin films grown in an acetate bath containing a 0.01 M Cupric Acetate having different bath pH values. The Mott-Schottky plots resulting from C-V measurements revealed that the flatband potential and doping density of the films strongly depended on the deposition bath pH. For pH values lower than 7.2, conductivity of Cu2O films remained n-type while it changed to p-type for higher pH values indicating that change of n-type to p-type character of the Cu2O films can be controlled by the bath pH. With increasing pH value, the grain size decreased, while crystal shapes transformed from truncated octahedral to cubic within the tested pH range. A well ordered cubic structure was observed in films deposited at pH 7.8. The rate of deposition decreased at higher pH values leading to thinner films indicating the effect of pH on the film thickness. Calculated band edge positions of conduction and valance bands of the Cu2O films were −4.19 eV and −6.29 eV respectively with respect to the vacuum level.

Electrodeposition of nanometer-thick epitaxial films of silver onto single-crystal silicon wafers

Silver films were deposited epitaxially for the first time onto low-index, single-crystal silicon wafers through an electrochemical method in an aqueous silver acetate bath.

Electrosynthesis of metallic molybdenum from water deficient solution containing molybdate ions and high concentrations of acetate

We prepare molybdenum (Mo) coatings by direct current electrodeposition. The acetate bath composition is fixed whereas different electrodeposition parameters such as temperature, deposition time, pH and current density are investigated to reveal their effects on the Mo coating properties (composition and mechanical properties). A compact and hard Mo coating (~20 μm thick, with a high hardness of 5551 MPa) was obtained from a neutral electrolyte at a deposition temperature of 30 °C and a current density of 0.4 A/cm2 over 8 h. The composition of the coating was confirmed to be 91% Mo through energy dispersive spectroscopy (EDS). The deposited coatings were shown to be nanocrystalline/amorphous via X-ray diffraction (XRD), which accounts for the high measured coating hardness.

Electrodeposition of copper oxides (CuxOy) from acetate bath

Herein, we report the study of the electrodeposition of copper oxides mainly Cuprite (Cu2O), paramelaconite Cu4O3 and tenorite (CuO) from a slightly acidic Cu(II) acetate solution on indium-doped tin oxide (ITO) substrate. A formation mechanism was proposed based on the observation of a series of reaction intermediates. The potential domain where the electrodeposition of copper oxides (CuxOy) is possible was investigated. The nucleation mechanism of (Cu2O) during electrodeposition was studied as a function of Cu2+ concentrations and deposition potential by exploiting the electrochemical techniques such as cyclic voltammetry and chronoamperometry. This study enabled us to demonstrate that the nucleation process and the growth of dendrites obey the model of Scharifker and Hills 3D instantaneous under diffusion control. Morphological and structural characterizations of the electrodeposit are performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Effect of Poly(N-vinyl-pyrrolidone) on Electrochemical Production of Cu Nanoparticles

Cu nanoparticles were synthesized via electrochemical deposition and the effect of the addition of poly(N-vinyl-pyrrolidone) (PVP) and pH on the properties of the nanoparticles was investigated. The Cu nanoparticles were prepared from an electrolyte containing copper acetate (pH 5.50) or copper sulfate (pH 4.14) by collecting the dispersed particles in the solution after electrochemical reduction. With the use of the acetate bath, formation of Cu2O at −0.2 and −1.5 V vs. Ag/AgCl was confirmed. On the other hand, Cu2O formation was not observed with the sulfate bath due to the lower pH, and the Cu nanoparticles could not be obtained at the potential of −1.5 V vs. Ag/AgCl. Surface enhanced Raman spectroscopy with plasmon sensors was used to investigate the transformations of PVP during electrolysis under the different conditions when Cu particles were and were not formed. For the dispersed nanoparticles in the electrolyte, it was observed that the C=O and C–N peaks of PVP also exhibited a red-shift. It was thus confirmed that PVP was coordinated to both the cathode electrode and dispersed nanoparticles in the electrolyte upon electrochemical reduction.

Fabrication and magnetic properties of ordered Co100−xPbxnanowire arrays electrodeposited in AAO templates: Effects of annealing temperature and frequency

Abstract

Electrodeposition of ZnO from Acetate Bath for Thermoelectric Devices

We attempted to form ZnO films with smooth surface for the application of thermoelectric micro-devices, using electrodeposition process. In order to reduce the defects of the films such as cracks and pits mainly caused by the gas evolution, the bath containing acetate in addition to nitrate ions was developed to reduce the gas evolution during the deposition. Using this bath, formation of ZnO, rather than Zn metallic films, was confirmed by Raman spectroscopy. The films had no cracks and the surface became smoother than those electrodeposited from the conventional nitrate-based bath. In order to fabricate the micro-devices, The ZnO was electrodeposited into the patterns with diameter of 200 μm. As a result, ZnO successfully filled the pattern keeping the smooth surface conditions, which demonstrated the applicability of the ZnO films to micro-device fabrication.

Effects of Surface Modification of n-Cu<sub>2</sub>O/p-Cu<sub>x</sub>S Thin Film Heterostructures for Enhanced Liquefied Petroleum Gas Sensing Properties

We report a novel mechanism to effectively detect LP gas based on surface modification through sulphidation followed by passivation of electrodeposited n-type cuprous oxide (Cu2O), forming a thin film nCu2O/p-CuxS semiconducting heterostructure. Electrochemically deposited n-type cuprous oxide (n-Cu2O) thin films on Ti substrates in acetate bath were sulphided using Na2S to fabricate n-Cu2O/pCuxS heterostructures. Subsequent passivation of these thin film structures using (NH4)2S vapor enhanced the sensitivity (fractional change in thin film resistance) when exposed to liquefied petroleum (LP) gas. Scanning electron micrographs (SEM) confirmed that typical unsulphided n-type Cu2O thin films exhibit polycrystalline surface morphology, while SEM of both sulphided and passivated thin films revealed micro/nano-crystalline surface morphological features with porous structures. As expected, the thin film structures obtained through sulphidation followed by passivation of n-type Cu2O films decreased the resistance (100 kΩ) in comparison to the resistance (1 MΩ) of the unsulphided n-type Cu2O thin films. Upon exposure to LP gas, the resistance of these thin film structures increased while, sensitivity to LP gas depended on the sensing temperature. Exposure of thin film structures fabricated by electrodepositing n type Cu2O thin films for 45 min, sulphided and passivated for 5 s and maintained at a sensing temperature of 45 oC to LP gas with a flow rate of 2.5 ml/min recorded the highest sensitivity of 48 %.

Electrodeposition of ZnO from Acetate Bath for Thermoelectric Devices

Among various fields where ZnO is applied, thermoelectric application has received considerable attraction because metal oxide materials have high thermal stability. Up to date, various methods to prepare ZnO have been studied. Among them, electrochemical process has several advantages such as low reaction temperature and process simplicity. Moreover, micro-device fabrication is applicable by using electrodeposition due to the selectivity of deposition. In numbers of reports, nitrate-based electrolytes were used and have been extensively investigated [1]. However, some drawbacks have still remained that ZnO films from nitrate solution have rough surface mainly due to gas evolution derived from nitrate ion, such as nitrogen. For the approach to solve this, the application of acetate bath was proposed. The merit of using acetate solution is the higher pH value in the bath than nitrate to prevent generation of hydrogen. Acetate is also advantageous for no gas evolution derived from nitrate. Therefore it is suggested the quality of ZnO films is improved by the acetate bath. We have attempted to obtain smooth ZnO films using acetate bath, however the bath was not stable and few papers have been published for the acetate bath. Moreover, for the application to the thermoelectric devices, the characterization of electrodeposited ZnO has not been performed yet. In this study, we demonstrated electrodeposition of ZnO films from not only nitrate but acetate bath and investigated the effect on morphology and deposition behavior by difference of Zn precursors. We further show the thermoelectric characterization of obtained ZnO by fabricating the thermoelectric device. Electrodeposition was conducted in a three-electrode system with a 700-μm-thick sheet of glass covered with 100 nm Au/10 nm Cr as working electrode, a Pt plate as counter electrode and Ag/AgCl as reference electrode, respectively. In the case of nitrate bath, the electrolytes were the aqueous solution containing 0.05 M Zn(NO3)2･6H2O and the applied potential was modified from -0.8 to -1.4 V. The bath temperature was controlled at 65, 75 and 85 oC. The deposition duration was 60 min. On the other hand, the acetate solution is containing 0.05 M Zn(OCOCH3)2･2H2O, 0.1 M CH3COONa and 0.1 M CH3COOH. The potential was applied from -0.8 to -1.3 V and the bath temperature was fixed at 65, 75 and 85 oC. The deposition was performed for 30 min. Finally using the solution mixed the Zn(NO3)2･6H2O and CH3COONa, the ZnO films were electrodeposited into patterns with the diameter of 200 μm. The morphology and crystallinity of the sample were characterized using FESEM, Raman spectrometer and XRD. Thermoelectric properties were measured by generating a thermal gradient using focused light from a halogen lamp as a heat source. First the electrodeposition process was carried out from the nitrate bath and the ZnO films were obtained. However, by using nitrate bath, hydrogen or other gases were generated resulting in the films with a lot of pits and low adhesion. In order to solve this problem, the acetate bath was applied. Although the electrodeposition was carried out from the acetate solution changing the applied potential or bath temperature, introducing the oxygen gas or additives, annealing the deposited films, Zn tended to deposit instead of ZnO under all conditions. The fact that ZnO was obtained using only nitrate was caused by the shift of the reduction potential of NO3 - ion towards less negative values in the presence of Zn2+. Therefore, the bath mixing both nitrate and acetate ion was used. As a result, Raman spectra showed the films electrodeposited from mixing bath was consisted of ZnO. The ZnO electrodeposited from the bath adding 0.05 M Zn(NO3)2･6H2O and 0.01 M CH3COONa has smooth surface and the adhesion was improved. Then using the same mixing bath, the ZnO films were electrodeposited at -0.9 V and measured the thermoelectric property, resulting that the film showed Seebeck effect as n-type semiconductor. Finally, the ZnO was electrodeposited into the patterns using the above mixing bath, and it was found that ZnO with smooth morphology was electrodeposited into patterns. These results indicated that ZnO electrodeposited from the mixing bath using Zn(NO3)2･6H2O and CH3COONa has smooth morphology and high adhesion, and ZnO was promising for thermoelectric material due to its thermoelectric property. [1] M. Skompska, K. Zarebska, Electrochimica Acta, Vol. 127, pp. 467-488, 2014

(Invited) Electrochemical Deposition of Thick and Adherent MnO2 Films for Thin-Film Batteries

Electrolytic manganese dioxide (EMD) is fabricated by anodic electrodeposition typically from acid manganese sulfate baths. After electrodeposition it is peeled from the electrode and ground into powder, hence poor adhesion is required. EMD powder is mainly used for primary alkaline-Zn and Li-ion batteries. EMD allows Li-ion intercalation in the open channels in the γ-MnO2 lattice. In our research group we are interested in adapting the EMD process for bulk batteries to be used for fabrication of thin-film Li-ion batteries. EMD thin films deposition was developed on different substrates. Scanning electron microscopy (SEM) and Rutherford Backscattering Spectrometry (RBS) measurements were performed to extract the film porosity. It was found that all the deposited films have similar porosity values around 50 %. Anodic electrodeposition of EMD films from conventional acid manganese sulfate baths is not possible on easy to oxidize substrates like TiN (passivation) or Ni (dissolution). For this reason a neutral and complexing acetate bath was used. Using this deposition bath thick and adhesive EMD film were deposited on Ni and even on TiN substrates. Up to 1 μm thick film on planar substrate and 600 nm on 50 μm high Si pillar array with 2 μm pillar diameter and 2 μm interpillar spacing. A study of the EMD film deposition in a temperatures range from 5 °C to 50 °C using the neutral acetate deposition bath was performed. The relationship between the morphology and the electrochemical performance of the EMD films deposited at different temperatures were investigated.