bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of the Discharge Rate Capabilities of Electrodes for Printed Nickel Based Batteries
Authors: Mabbett Ian , Glover Carol , Marinaccio Jordan , Worsley David A , Williams Geraint
Published: February 2020

Printed micro-batteries could be used in a variety of small electric circuits such as RFID and sensors. Printing techniques can facilitate high volume manufacture in economical processes that have much to offer in energy storage applications. Utility scale electrochemical energy storage will also become an important topic as countries across the globe set targets for highly distributed electricity generation from renewable sources. Time shifting via appropriate energy storage installations as well as peak shaving to stabilise national grids will become an important part of future electricity infrastructures where electrification of transport and heating become commonplace. To meet the demands of such a market stationary, utility scale energy storage technologies must be safe, offer long lifetimes and have inherently low cost. This can be achieved by the use of earth abundant materials and by employing rapid, roll-to-roll, solution coating or printing processes.

Micro-batteries and utility scale energy storage solutions all have different demands in terms of capacity and rate capabilities. Design of electrodes to optimise energy storage can hinder the ability to deliver power and achieve high current densities.

This study describes how print parameters and sinter conditions can be varied to find compromises between kWh capacity stored and kW power that can be delivered on demand. Typical strategies to reduce activation polarisation and increase conductivity of electrode pastes usually result in less available active material to support charge transfer, thus lowering the useful capacity of the cell. This work describes how optimising printing processes to deliver a balance of active material availability and high rate capability can produce versatile electrodes. Sinter conditions are also investigated to strike a balance between the adhesion of the sintered electrode material to the substrate and controlled highly porous sintered structures required to promote adequate mass transport through the porous network of the electrode.

Physical characteristics of the printed electrodes are confirmed by SEM micrographs, profilometery and BET surface area and porosity measurements with the rate capabilities and capacities assessed galvanostatically. EIS and novel scanning electrochemical techniques shed further light on the impact of print and sinter parameters in electrochemical performance.
A Carbon-Free, Precious-Metal-Free, High-Performance O2 Electrode for Regenerative Fuel Cells and Metal-Air Batteries
Authors: Ng Desmond , Tang Maureen Han-Mei , Gorlin Yelena , Hatsukade Toru , Jaramillo Thomas Francisco
Published: February 2020

There have been extensive research efforts focusing on developing technologies for renewable electricity, particularly solar photovoltaics and wind turbines. However, the intermittent and localized nature of wind and solar energy necessitates the development of a cost-effective way to balance energy supply and demand and to deliver electricity from remote places to cities.[1] The short-term option is the electricity grid; however, it can only support intermittent renewable electricity in a stable fashion up to approximately 20 % of grid capacity which means that fossil resources would still account for the remaining 80 % of grid electricity.[2] Clearly, the development of cost-effective energy storage devices is needed to establish a path toward fossil-free energy.

The development of high-performance and cost-effective electrodes for oxygen evolution and oxygen reduction is critical for enabling the use of energy storage devices based on O2-H2O chemistries such as metal-air batteries and unitized regenerative fuel cells (URFCs).[3] Herein, we report a precious-metal-free and carbon-free O2 electrode synthesized via electrodeposition of manganese oxide (MnOx) on a stainless steel (SS) substrate followed by high-temperature calcination at 480 oC. The MnOx-SS electrode displays high oxygen reduction and water oxidation activities when tested in an electrochemical cell, comparable to that of a precious-metal based electrode, Pt/C-SS. Accelerated durability testing reveals the excellent stability of the MnOx-SS electrode compared to both the Pt/C-SS electrode and a carbon-based electrode with MnOx and Ni catalysts. This can be rationalized by the carbon-free nature of the MnOx-SS electrode which circumvents carbon corrosion at the high electrochemical potentials during water oxidation and O2 reduction. Integrating the MnOx-SS electrode as the O2 electrode in an anion exchange membrane (AEM) URFC produces round trip efficiencies of 42-45 % at 20 mA.cm-2 over 10 cycles, and exhibits significantly enhanced durability compared to the carbon-based analogue. This work demonstrates the MnOx-SS electrode’s potential for use as a high performance, scalable, precious-metal-free and carbon-free O2 electrode in AEM-URFCs and metal-air batteries.

References

[1] Z. Zhan, W. Kobsiriphat, J.R. Wilson, M. Pillai, I. Kim, S.A. Barnett, Energ. Fuel.
2009, 23, 3089.

[2] W. Kempton, J. Tomić, J. Power Sources
2005, 144, 280.

[3] J.W.D. Ng, Y. Gorlin, T. Hatsukade, T.F. Jaramillo, Adv. Energy Mater.
2013, 3, 1545.
Diagnostic Criteria for Mass Lesions Differentiating in Electrical Impedance Mammography
Authors: Uddin Hameed , Khosla Ajit
Published: February 2020

Currently, there emerged a necessity of a standardized description of volumetric lesions and developing of a system for volumetric lesions description in the mammary gland to be in line with ACR BI-RADS categories. The purpose of this research was to determine the diagnostic criteria for differentiating volumetric lesions in the mammary gland in electrical impedance mammography. The research was carried out utilizing the electrical impedance computer mammograph «MEIK v.5.6»®, which enables to acquire images of 3-D conductivity distribution layers within mamma’s tissues up to 5 cm depth. The weighted reciprocal projection method was employed to reconstruct the 3-D electric conductivity distribution of the examined organ. The results of 3,710 electrical impedance examinations were analyzed. The analysis of a mass lesion was conducted in BI-RADS ACR terms and included assessment of its shape, contour, internal electrical structure and changes of the surrounding tissues. Moreover, mammary gland status was evaluated with the help of comparative and age-related electrical conductivity curves. The diagnostic charts were built and will be discussed in this talk. Each criterion was measured in points. Using the numerical score for evaluation of volumetric and non-volumetric lesions within the mammary gland in electrical impedance mammography allowed comparing this information to BI-RADS ACR categories
The Effects of Morphology on the Dielectric and Mechanical Properties of Parylene-C Microfibrous Thin Films
Authors: Khawaji Ibrahim H , Chindam Chandraprakash , Orfali Wasim , Lakhtakia Akhlesh , Awadelkarim Osama Osman
Published: February 2020

Silicon-based CMOS material set is rather restrictive for the realization of the full potential of NEMS/MEMS and, hence, a wide spectrum of new material compositions and morphologies are being explored nowadays. Because of its extensive applications in electronic and medical devices as well as because of its chemical inertness and thermal stability, a polymer called Parylene C was used to grow microfibrous thin films using physicochemical vapor deposition in a PDS2010 Parylene-C labcoater on p-type Si or brass substrates. The thin films are assemblies of parallel microfibers tilted at an angle χv with respect to the substrate plane. During deposition, a collimated vapor flux of Parylene C was directed at an angle χv with respect to the same plane. Values of χv used were 10°, 25°, 45°, 60°, and 90°. Both χ and the mass density increase with increasing χv. Using Parylene-C microfibrous thin films as the dielectric layers in metal-insulator–semiconductor (MIS) and metal–insulator–metal (MIM) capacitor structures, we were able to study their dielectric properties. The dependence of the “effective” relative permittivity eeff on χv was observed to be controlled by the amplitude of the applied AC signal, and eeff was found to decrease with increasing signal frequency. The MIS and MIM leakage current was used to study the dependence of hopping conduction on both the frequency and the temperature. These observations were interpreted relative to series/parallel networks of miniature resistors and capacitors. Also, we undertook a dynamic mechanical analysis, whereby a Parylene-C microfibrous thin film was clamped at two ends and subjected to cyclic loading. The storage and the loss moduli were measured as functions of frequency, in the frequency range 5 to 200 Hz, and temperatures up to 125 °C. The glass transition temperature was identified as 65 °C from the temperature maximum of the loss modulus.
Integration of PVDF (Polyvinylidene Fluoride) in MEMS Production
Authors: Holz Stephanie , Kiricenko Sergej , Rissing Lutz
Published: February 2020

Introduction

The combination of materials with new processing setups often leads to new opportunities in well-known technologies. Polyvinylidene fluoride (PVDF) is widely used because of its chemical resistance and thermal properties. Usually, it is shaped by spray casting to produce plumber components. PVDF is also known for its piezoelectric behavior, which can be measured in PVDF films, like it was shown by Kawai [1] and others long ago. Nevertheless, piezoelectric materials are used in MEMS production, PVDF is not. Therefore, the main idea is to evaluate the possibilities and afterwards creating a way for the integration of PVDF in MEMS production for example as membrane for flexible parts with piezoelectric behavior.

Solubility and Spin coating

As a substrate with a high chemical resistance, PVDF is only soluble in a few solvents. However, to use PVDF films does not seem promising, because of the inclosed gas bubbles, the difficulties to produce thin films and the need to reach a bond between film and wafer.

Spin coating was chosen to get PVDF films on wafer substrates. To obtain a photoresist like solution of PVDF, three different solvents (DMF, DMAc, NMP) were tested. Each showed good solution result, even though it took up to several days to get a homogeneous solution.

Spin coating was performed with each solution. Afterwards the reached thickness of the PVDF layer was measured. A connection between amounts of PVDF in solution and thickness could be found as well as between the different solvents used for the solutions.

Measurement and cumulation of the piezoelectric behavior

For the following experiments, several wafers were prepared with PVDF by spin coating. Some were dried under standard conditions (95°C, 5 min). The others were dried in an electric field, to reach an increasing in the piezoelectric behaviour. These PVDF film were compared to PVDF films that were exposed to an electric field in solid state. The setup for that is shown in picture A.

The setup for the exposure of the liquid PVDF is far more complex because a defined air gap is needed during the baking process. Therefore, the setup was changed. The wafer is placed on the heating plate, which is used as on electrode. The other electrode is located parallel to the wafer with a small air gap of at least 4 mm.

A relation between electric field and piezoelectric behavior could be shown. Therefore the method seems promising. Picture B shows the results of the first spin coating tests with PVDF as membrane material for flexible parts.

[1] H. Kawai, “Piezoelectric Effect in Polarized Poly (vinylidene Fluoride)”, Japan. J. Appl. Phys., 8, 975, 1969
New Trends in Chemistry at Steps Due to Mechanical Stress and Relevance to Corrosion
Authors: Francis Michael F , Curtin William A
Published: February 2020

Theoretical investigation of surface chemistry has had many successes including but not limited to surface structure, phase stability, chemical kinetics, electrochemical modeling, and solution phase chemistry. Yet developed is a method for the investigation of the influence of an arbitrarily applied stress to an arbitrary surface structure. In this work the linear elastic theory of mechanics is applied to the surface structure to investigate precisely this. Chemisorption over a wide variety of late transition metals is studied and it is shown that the change in chemisorption energy due to an applied stress is non-uniform. For example, when stress is applied parallel to or orthogonal to the line of a step the chemical response is not necessarily the same. Furthermore, the chemical response at defects is inconsistent between materials. These phenomena are demonstrated, analyzed in terms of known theory such as d-band theory. It is shown that at steps a departure from d-band theory occurs due to mechanical contributions to the binding energy of species under stress. This mechanical contribution to chemistry provides a new framework to consider when thinking of surface chemistry under stress and is discussed in terms of crack tip chemistry.
Ångstrom Resolved Real-Time Monitoring of Oxide Growth and Reduction on Noble and Engineering Metals
Authors: Valtiner Markus , Cheng Hsiu-Wei , Shrestha Buddha Ratna , Baimpos Theodoros , Raman Sangeetha
Published: February 2020

Structure and dynamics at electrochemical metal/liquid interfaces determine lifetime and stability of advanced and structural materials, and are fundamental to corrosive processes. Here, we present recent experiments with the newly developed and unique electrochemical surface force apparatus1,2, which allow us to unravel electrochemical oxidation and reduction processes in real-time at well-defined and nano-confined electrodes. In particular, we monitor metal-oxide thin film formation with Å-accuracy during potentiostatic and potentiodynamic polarizations. In confined spaces we find unexpectedly strong electrochemical depletion forces acting between apposing surfaces during active electrochemical processes. Depending on the conditions, these forces are repulsive and can strongly overpower attractive Van der Waals forces, and the associated electric-field gradients might have significant effects in corrosive processes occurring in nano-confined spaces (such as crevices or pits). In addition, using the EC-SFA we have, for the first time, monitored oxide growth and reduction on noble metals (Au, Pt, Pd and Ir) in sulfuric acid solutions, as well as Nickel and Aluminum corrosion in confinement situations, with Ångstrom resolution in thickness and in real time with milliseconds resolution. Our experiments reveal stark differences of oxide thickness and its electronic properties during potentio-dynamic and potentio-static oxide growth, which will be discussed in the presentation.

1. Valtiner, M. et al. The Electrochemical Surface Forces Apparatus: The Effect of Surface Roughness, Electrostatic Surface Potentials, and Anodic Oxide Growth on Interaction Forces, and Friction between Dissimilar Surfaces in Aqueous Solutions. Langmuir
2012,
28(36), 13080-13093.

2. Israelachvili, J. N. et al The Intersection of Interfacial Forces and Electrochemical Reactions. J. Phys. Chem B, 2013, 117 (51), 16369–16387.
Evaluation of the Electrochemical Behavior in Acid Media of HVOF-Spray Alloy Coatings
Authors: Cabral Miramontes Jose Angel , Achem Calahorra Jamnie Yazmin , Trujillo Estrada Ariadna , Pedraza Basulto Gabriela , Poblano Salas Carlos , Almeraya Calderon Facundo
Published: February 2020

In the aircraft and aerospace industry, coatings obtained by thermal spraying HVOF are use in some components of steam turbines, due to the passage of gases at high temperatures cause of the rotation of the wing which is subjected to severe static and dynamic load, usually associated with microstructure degradation mechanisms as corrosion, wear and creep. The MCrAlY coating ( M = Co or Ni ) type applications are used to provide wear and also corrosion resistance. In this work a HVOF gun was used to prepare a MCrAlY coating which has been subjected to two electrochemical techniques: polarization resistance and cyclic polarization curves in order to obtain the behavior of the rate of corrosion in acid and neutral media. The results show that the acid factor in the solution play an important role in the corrosion resistance of MCrAlY coating applied by HVOF thermal spraying.
Current Distribution in Reinforcing Steel Cathodically Protected by Cement Paste Anode
Authors: Barrios Carlos P. , Nuñez Rosa Elba , Castorena Jose H , Pellegrini Manuel Jesus , Maldonado Erick E. , Garcia Jorge P.
Published: February 2020

The present work shows the study of the distribution of current and electrochemical potential in the reinforcing steel by using as anode a layer of cement paste added with graphite powder and carbon fiber. The research was carried out on concrete slabs with w / c ratio of 0.5. Each slab is placed 12 steel rods. One of the slabs was contaminated with Cl- added in the mixing water 5% NaCl by weight. Was applied on each slab a layer thickness of 1cm conductive cement paste. Was measured current draw of each rod as well as the polarized potential. The use of a cement material conductive paste shows a good performance as anode in the PCCI reinforcing steel to achieve maintain polarized potential of-800mV.
Study of the Hydrodynamic Conditions of the 2-Mercaptoimidazole Inhibitor Derivatives for Mild STEEL Immersed in NaCl at Neutral pH
Authors: Espinoza Araceli , Palomar Manuel , Romero Mario Alberto , Buendia Erika
Published: February 2020

Introduction

Recently, our research group has demonstrated that some organic molecules such as 2-MBI derivatives can be also considered as an effective corrosion inhibitors for carbon steels in acidic media.

Results

Fig. 1 shows the variation of the corrosion inhibition efficiency, which indicates that at low concentrations the best inhibitor was the 2-mercaptoimidazole (2MI) giving 90% IE at 10 ppm, thus being the least efficient the 5-nitro-2-mercaptobenzimidazole (5N-2MBI) with an efficiency of 80% inhibition at 200 ppm.

Moreover, this compound follows an adsorption mechanism, which can be adequately described by the Langmuir isotherm thereby pointing to a physisorption process on the metal surface.
Investigation of the Fundamental Processes in the Internal Oxidation of Binary and Ternary Iron Based Alloys at Elevated Temperatures
Authors: Rohwerder Michael , Borodin Sergiy , Vogel Alexandra , Vogel Dirk
Published: February 2020

In different production steps steels are exposed to high temperature either in reducing condition (for e.g. N2-H2during recrystallization annealing) or in oxidizing environments (e.g. during hot rolling and cooling after hot rolling). These processes are accompanied by external and internal oxidation, which can affect further processing steps. For example, during cooling after hot rolling of high strength steels especially grain boundary oxidation can lead to significant problems during pickling and cold rolling. In this paper a fundamental investigation of grain boundary oxidation during annealing under model atmospheres simulating the oxygen partial pressure beneath the scale will be addressed, based on model alloys which are relevant to industrial steel grades. The focus will be on questions such as how the different alloying elements and the various annealing conditions influence the internal selective oxidation.

In order to develop a fundamental understanding, binary and ternary model alloys (for instance, Fe-Mn, Fe-Cr etc.) are considered. Significant focus will be given to the oxidation kinetics i.e., monitoring of the mass gain during isothermal oxidation using a thermo-gravimetric balance (TG). The partial pressure of oxygen during the experiments is kept just below the equilibrium pressure for FeO/Fe. As the mass changes during internal oxidation are very low, errors from buoyancy effects in a standard set-up are in the same range as the mass change to be investigated. Hence, a novel under-pressure TG set-up was developed and applied here. In this under-pressure TG the same gas composition of water vapor and hydrogen are used, but the inert carrier gas N2is omitted, significantly decreasing buoyancy effects. Thus the mass gain measurement is carried out with so far unequaled accuracy.

Furthermore, the role of elemental segregation to the grain boundaries on grain boundary oxidation was investigated. The results will be discussed also on the basis of earlier simulation work [1].

[1] M. Auinger, S. Borodin, S. Swaminathan and M. Rohwerder, Materials Science Forum 696 (2011) 76-81
Examination of the Electrochemical Compatibility of a Selection of Bimetallic Coins Using 3D-Skp and 3D-Svet
Authors: Searle Justin Royston , Glover Carol Frances , Khan Khalil , Williams Geraint , Worsley David A
Published: February 2020

Coins as a means of exchange or barter have existed for over 2000 years. Early examples from the Bronze Age were stamped from crudely shaped discs of metal and this principle of manufacture has continued through to the present day. With the face value of modern coins usually being significantly higher than the material value and production cost, they can be prone to forgery, with a reported 3% of certain denominations in the UK being counterfeit1. In an effort to combat this and to add distinguishing features to the different denominations, an increasing number of coins around the world consist of two or more alloys. These are usually arranged as an inner and outer piece, to form two concentric rings. With two different alloys in electrical contact there exists the possibility for bimetallic corrosion to occur; hence it is important that the two alloys are potentiometrically matched. In this study, a selection of bimetallic coins has been examined via 3D-SKP and 3D-SVET. The SKP technique is used to examine the surface potential differences between the two alloys. The SKP scans have been performed using height scanning mode in order to compensate for the topographical features present and enable a sufficiently close scan distance to elucidate good potential measurements. Subsequently the coins have then been subjected to 3D SVET scans while immersed in an electrolyte, in order to assess if the potential differences identified during the SKP assessment result in measureable galvanic corrosion.

The SKP was able to determine a Volta potential difference of between 50 – 100mV for the paired alloys. When investigated via the SVET, this relatively small potential difference was sufficient to generate measureable galvanic corrosion currents when immersed in weak electrolyte and scanned using the 3D-SVET. The anodic and cathodic sites detected via the SVET corresponded to the relative Volta potentials as detected with the SKP.

Osbourne, G. (2014),
Chancellor George Osborne's Budget 2014 speech
, Available: https://www.gov.uk/government/speeches/chancellor-george-osbornes-budget-2014-speech [20 March 2014].
Electroforming Nanostructured-Based Thermoelectrics
Authors: Arrington Christian L. , Sharma Peter A. , Burleigh T.D. , Banga Dhego , Yelton W. Graham , Baca Ehren D
Published: February 2020

Thermoelectric (TE) materials offer engineering solutions for applications such as cooling without moving parts and conversion of waste heat to electricity. However, devices using existing thermoelectric materials suffer from poor efficiency and high cost. Electrochemical deposition (ECD) has the potential to make the synthesis of thermoelectrics more cost effective and potentially enhance thermoelectric properties. The best thermoelectrics to date are thin film super lattices, fabricated using vapor phase methods [1]. However, these materials have a greatly limited application space due to their limited thickness (~ 10 µm). In this work, ECD techniques are used to nanostructure Bi2Te3 based thermoelectric materials over large areas and thicknesses, as well as electroforming it into a mold to enable future batch fabrication. Multiple experiments were performed to better understand scalability of thermoelectric film growth. Large grain boundaries were found to affect density and stoichiometry of the material impacting TE performance. A 7 liter chemistry make-up and ECD conditions are established targeting wafer scale batch fabrication. The highest Seebeck, 85 µV/K, was found when deposited in small electroformed posts with a resistivity of 5 mΩ cm.

[1] R. Venkatasubramanian, E.S., T. Colpitts, B. O'Quinn,, Nature, 2001. 413: p. 597.
Synthesis and Characterization of Metal- and Non-Metal-Doped Titania Nanotubes for Solar Hydrogen Generation and Methanol Electrooxidation
Authors: Karimi Shahram
Published: February 2020

Functional nanostructured TiO2 materials with unique electrical, chemical and catalytic properties are being increasingly used in many applications, including lithium-ion batteries, gas sensors, hydrogen generation, electrocatalysis and photocatalysis. A number of different pathways and processes have been developed and reported to synthesize titania nanotubes (TNTs), nanorodes, and nanospheres. The most common methods include sol-gel, hydrothermal treatment, electrophoretic deposition and electrochemical anodization. The latter technique has been utilized by many researchers to fabricate highly ordered titania nanotubes and, subsequently, doped with both metals and non-metals. The last step—inclusion of metals and non-metals into the TNT matrix—is critical for solar hydrogen generation since pure titaina is insufficient under visible light due to its wide band gap, which is around 3.2 eV. Furthermore, metal oxides such as titanium dioxide suffer from lower surface area and electrical conductivity compared with carbon-based materials for use in direct methanol fuel cells. Accordingly, they are often combined with carbon-based materials and/or transition metals to form oxide-carbon hybrid structures.

Highly ordered titania nanotubes (Figure 1) were fabricated employing a simple electrochemical anodization technique in a conventional two-electrode cell with titanium foil and graphite as working and counter electrodes, respectively. Metals, including nickel and platinum, were electrodeposited on TNT or TNT-C materials using a pulsed current electrodeposition technique [1]. All samples were then characterized by scanning electron microscopy, X-ray powder diffractometry, cyclic voltammetry, and chronoamperometry. Structural examination of the samples confirmed the presence of rutile and anatase nanocrystalline TNTs after annealing at different temperatures and durations. The presence of nanoparticles, including platinum and nickel, were also confirmed.

For methanol electrooxidation, the activity and durability of the hybrid catalyst layers were determined in a solution containing one molar sulfuric acid and one molar methanol. The hybrid catalyst layer showed a better performance towards methanol oxidation compared with state-of-the-art carbon-supported platinum layers. For solar hydrogen generation, the efficiency of the photoanodes was found to increase as the amount of dopant increased to 3.0%. Further increase in dopant, however, resulted in a decrease in efficiency, possibly due to a higher rate of electron-hole recombination.

Reference

1. S. Karimi & F.R. Foulkes, Electrochemistry Communications
19 (2012) 17-20
Fabrication of a Complete Photovoltaic CIGS Device by Electrodeposition
Authors: Saeed Mahfouz Ali , Landau Uziel
Published: February 2020

Copper Indium Gallium Selenium (CIGS) films are attractive for photovoltaic applications due to their high optical absorption coefficient. Generation of CIGS films by electrodeposition is particularly appealing due to the relatively low capital cost and the relatively high throughput1-3. Numerous publications address the electrodeposition of CIGS; however, to our knowledge, none reports the fabrication of a complete CIGS photovoltaic cell using electrochemical techniques.

In this work we introduce electrochemical processes that enable the fabrication of complete CIGS and CIGSS functional photovoltaic devices, based entirely on electroplating. The electrodeposition of the CIGS or CIGSS absorber layers is based on an electrolyte that is far more dilute than systems that had been traditionally used, and which yields much improved CIGS and CIGSS films4,5. In addition to the absorber layer, electrochemical processes for the electrodeposition of the cadmium sulfide (50 nm), and the pure zinc oxide (100 nm) layer are described. Also the electrodeposition of doped zinc oxide (0.5 µ) (window layer) is discussed. The substrate has been stainless steel coated with electrodeposited metal barrier (Ni, Cr, or Cu), enabling continuous strip plating. An intermediate molybdenum layer, providing improved interface to the absorber layer, increased the efficiency. The final device structure is shown in figure 1.

Complete electrodeposited devices were generated and tested exhibiting efficiencies ranging from 2 to 6% with quantum efficiency exceeding 0.6 as shown in figure 2. A comprehensive electrochemical process such as described here, will enable the fabrication of the entire device through a fast wet chemical process, providing effective manufacturing integration and scaling.
The Development of a Chemistry and Process for Cu Damascene Plating – from Research to Development to Manufacturing
Authors: Huang Qiang , Ahmed Shafaat , Kitayaporn Sathana , Avekians Alex , Kelly James , Sahin Asli , Liu Jun , Sun Ying , Cheng Tien , Baker-O'Neal Brett
Published: February 2020

Electroplated Cu lines has been successfully used in the back-end-of-the-line (BEOL) interconnects in the IC industry for more than a decade.[1,2] As the technology continues to advance and the dimension continues to scale, advanced Cu plating chemistry is always in demand to meet the defectivity, electrical yield and reliability requirements.

A typical three-component chemistry consists of a suppressor, an accelerator and a leveler. Among them, the suppressor and accelerator are generally thought to enable the super conformal filling.[3-7] While the presence of the leveler is believed to have little impact on the super filling, it mitigates the surface topography as a result of the so-called momentum plating.[8-10] In addition, the leveler also provides a way to control the impurity in the plated Cu as well as the cosmetic defects on the Cu surface.[10-12]

In this talk, we will showcase how a new plating chemistry was developed, commercialized and implemented for semiconductor manufacturing. The full cycle of research, development and manufacturing implementation and their correlations will be presented.

REFERENCES

1 P. Andricacos et al., IBM Journal of Research and Development 42 (5), 567 (1998).

2 D. Edelstein et al., Proceedings of International Electron Devices Meeting, IEDM, (1997).

3 T. P. Moffat et al., Journal of The Electrochemical Society 147, 4524 (2000).

4 T. P. Moffat et al., Electrochemical and Solid-State Letters 4, C26 (2001).

5 A. C. West, S. Mayer, and J. Reid, Electrochemical and Solid-State Letters 4, C50 (2001).

6 T. Moffat et al., IBM Journal of Research and Development 49 (1), 19 (2005).

7 R. Akolkar and U. Landau, Journal of The Electrochemical Society 151, C702 (2004).

8 S. Kim, D. Josell, and T. Moffat, Journal of The Electrochemical Society 153, C826 (2006).

9 T. P. Moffat et al., Journal of The Electrochemical Society 153, C127 (2006).

10 J. D. Reid et al., Proceedings of 205th ECS Meeting - International Symposium on Electrochemical Processing in ULSI and MEMS, San Antonio, TX, (2005).

11 J. Sukamto and J. Reid, Proceedings of 205th ECS Meeting - International Symposium on Electrochemical Processing in ULSI and MEMS, San Antonio, TX, (2005).

12 J. D. Reid and J. Zhou, Proceedings of 209th ECS Meeting - International Symposium on Electrochemical Processing in ULSI and MEMS 2, Denver, CO, (2007).
Electrochemical Synthesis of High Strength Nanotwin Copper Films
Authors: Wang Geon , Seo Sungho , Jin Sanghyun , Yoo Bongyoung
Published: February 2020

Copper is the common materials for the semiconductor and battery industry. Especially, electrodeposited copper is the most widely used for its excellent electrical, physical properties and low cost. Recently, high strength copper thin film with also high conductivity is urgently required. Generally, according to the Hall-Petch relation, the grain size decrease causes tensile strength of copper. However, electrical conductivity was significantly decreased by this strengthening method as electron scattering can be caused by grain boundary.

In this study, electrochemical deposition of copper by pulse and pulse reverse current with extremely high peak current density was investigated. Various experiments were carried out to control the microstructure and achieve the high mechanical and electrical property. Pulse reverse current is applied to anodic current instead of off time in the pulse current. This process accelerates stress relaxation of copper film, we expect that reduce the deposition time compared with pulse current and direct current (dc) deposition.

Besides current adjustment, there are two classification of organic additives, are in suppressor which inhibit the copper reduction reaction, such as Polyethylene glycol (PEG), another is accelerator which oppositely increase copper reduction reaction, such as bis-(3-sulfopropyl)-disulfide (SPS).

Moreover, we investigated organic additive behavior in pulse and pulse reverse current electrodeposition copper films, the relation between organic additives and nano scale twin structure. As a results, tensile strength of copper film by pulse current is significantly higher than dc deposited copper film (Figure 1) and electrical conductivity is similar to dc deposited copper film (~1.9μΩ·cm). Enhanced tensile strength of copper thin film is related with microstructure. Especially, twin structure in the grain is strongly associated with tensile strength of copper films. As shown in the figure 2, high density of twin boundary structure is observed
Switching Behaviors of Co/Pt Nanodots and Its Dynamics under the Assistance of Rf Field
Authors: Okamoto Satoshi , Kikuchi Nobuaki , Furuta Masaki , Kitakami Osamu , Shimatsu Takehito
Published: February 2020

Microwave assisted switching (MAS) of magnetization has been expected as a key technology for future ultra-high density magnetic recording [1,2]. In this switching mode, large amplitude precessional motion of magnetization excited by applying an rf field with GHz frequency range promotes the magnetization switching even in a much smaller field than the coercivity. We have systematically studied the MAS effect on perpendicular magnetic Co/Pt multilayer nanodots [3-5]. From our elaborated experiments, it is found that the non-uniform magnetization precession such as spin wave significantly enhances the MAS effect.

The Co/Pt dots with diameter ranging from 50 nm to 330 nm were lithographically fabricated on a cross-shaped Pt electrode for anomalous Hall effect (AHE) measurement. The rf field was generated from a Cu strip line with 2 μm in width fabricated just above the dot with insertion of an insulating layer. Fig. 1(a) shows the switching field H
sw of a single Co/Pt dot of 120 nm in diameter as a function of rf frequency f
rf for various rf field amplitude h
rf. For h
rf = 450 Oe, the H
sw significantly decreases from 5.5 kOe to 2.1 kOe with increasing the f
rf until the critical frequency. In the range above the critical frequency, the H
sw steeply increases and coincides with the value obtained in the absence of rf field. It should be addressed that this significant reduction of switching field is much more profound than the theoretical prediction based on the single macrospin model. To elucidate the switching mechanism, dot size dependent switching behaviors are studied as shown in Fig. 1(b). H
sw gradually decreases with increase in the dot diameter. In this figure, simulation results based on two different models, that is, single macrospin and finite cell models, are also plotted. It is very interesting that H
sw for larger and smaller dots agree with the finite cell and single macrospin simulation results, respectively. The finite cell simulation reveals that the this largely enhanced MAS effect for larger dot is resulted from the excitation of non-uniform magnetization precession. This size dependent switching behaviors are well explained by the spin wave dispersion theory for a magnetic disk.

This work was partially supported by Grant-in-Aid for Sciencetiﬁc Research from MEXT, the Management Expense s Grants for National Universities Corporations from MEXT, Strategic Promotion of Innovative Research and Development from JST, and the Storage Research Consortium in Japan.

[1] C. Thirion et al., Nature Mater. 2, 524 (2003), [2] S. Okamoto et al., APL 93, 102506 (2008), [3] S. Okamoto et al., APEX 5, 093005 (2012), [4] S. Okamoto et al., PRL 109, 237209 (2012), [5] M. Furuta et al., APEX 6 (2013) 053006.
Magnetohydrodynamic Effects in Electrodeposition Reactions
Authors: Bund Andreas , Ispas Adriana , Mutschke Gerd
Published: February 2020

This paper will discuss the effect of magnetic fields in electrodeposition reactions. The best studied effect is the magnetohydrodynamic effect which is due to the Lorentz force. In general Lorentz forces are generated in the electrolyte where the cross product of current density and magnetic flux density is different from zero. At places where the curl of this force density does not vanish a flow is driven. This in turn causes an increased mass transport and thus higher deposition rates in an electroplating cell. Of course the magnetically driven flow will always interact with other types of convective flows in the cell, e.g. the natural convection.

By tailoring the magnetic field (e.g. via its gradient) the uniformity of electroplated layers can be enhanced [1]. Also the structure of deposits (e.g. in the case of nickel fine-grained vs. coarse-grained) can be affected by the magnetic field [2]. Corresponding examples from the author's labs will be discussed in this paper.

In this contribution we will also show that numerical simulation is a powerful tool if one wants to harvest the full potential of magnetic flow control in electrochemical reactions.

References

[1] S. Mühlenhoff, G. Mutschke, M. Uhlemann, X. Yang, S. Odenbach, J. Fröhlich, K. Eckert. Electrochem. Commun. 36 (2013) 80.

[2] A. Ispas, H. Matsushima, A. Bund, B. Bozzini. J. Electroanal. Chem. 626 (2009) 174.
Influence of EDTA on the Electrochemical Removal of Mercury (II) in Soil
Authors: Robles Irma , Bustos Erika , Serrano Tania
Published: February 2020

The electrokinetic treatment (EKT) is based on the generation of an electric field from the imposition of a direct current or potential using electrodes (anode and cathode), which are placed in pit excavated soil. For the EKT is required moistened with an electrolyte to improve the driving electric field. The EKT has shown ability to remove organic compounds, but more efficiently for metals such as Cr, Cd, Hg, Pb, Mn, Zn, and As with removal efficiencies close to 100 % when pollution is caused by a single metal. In field applications, the results are variable, depending on the type of soil, the type of pollutant and technological use. Studies have been conducted on the recovery of metals with sequestering agents, EDTA being the most efficient by the synthesis of strong complexes with metals like mercury in major proportion close to the anode by the negative charge of EDTA2-, which was moved by electric field to positive anode rounding the mercury ion: Hg2+.

Polarization curves were done in order to determine energy requirement, the highest removal of mercury in soil and clay was applying 1 V (close to 60 % removal). EKT was carried out at different time of treatment: 1, 3, 7, 9, 11 and 13 h, using 0.1 M HCl and 0.1 M EDTA quantifying mercury removal, pH, and conductivity. Results indicated that the highest mercury removal efficiency was obtained in bentonite with 66 % in a period of 13 h using HCl (cathode efficiency); while 70 % was removed in 9 h in the presence of EDTA (anode efficiency). On the other hand, the higher efficiency for soil in the presence of EDTA was 70.7% with pH 4 and 11.3 mS cm-1 close to the anode by the Hg2+-EDTA2- synthesized complex, and only 29.3 % was removed in the presence of HCl with constant pH 4 and a conductivity of 11 mS cm-1 by the absent of some complex.
Electrochemical Degradation of Azo Dyes using Graphene/Fto As Cathode and Platinum/Ti As Anode
Authors: Baltazar Juan CARLOS , Carreño Gilberto , Fuentes Rosalba , HernÁndez Venus AMANDA , Ortiz Josefina , Rivera Fernando Felipe
Published: February 2020

One of the most water polluting impact on the environment are dyes produced in various industries, mainly textile. An estimated 10-15% of the dyes used in these industries are thrown in the waste water. Chemicals containing dyes (including azo) are related to the presence of toxic compounds with chromophores groups of high molecular weight which to accumulate in lakes and rivers causing decrease in the brightness of the water and consequently induce the decrease of photosynthetic activity and decrease in available oxygen content in the water. In this work the electrochemical degradation of organic azo dye (Disperse Blue 3) will be presented. The degradation is carried out using the technique of chronoamperometry, calculating the anodic and cathodic potential of the system using calomel reference electrode. Phosphate buffer solution (1M) at pH 7.4 will be used as a supporting electrolyte. Graphene oxide supported on tin oxide dopped with fluor (FTO) will be use as cathode active electrode and platinum on titanium as anode active electrode. All systems of electro degradation will be built inside the 1cm x 1cm x 5cm quartz cell of the ultraviolet-visible spectrophotometer and measurements will be taken insitu during the process of electrochemical degradation. The cathode and anode are in separate cells joined by a salt bridge. Experiments are performed by applying an anodic potential before and after the production of oxygen at the anode, employing a power supply after the porduction of oxygen.

The authors are grateful to CONACYT and CONCYTEG for the economic support via the projects FOMIX GTO-2012-C04-195057

REFERENCES

1. - A Comparative study on oxidation of disperses dyes by electrochemical process, ozone, hypochlorite and fenton reagent by Lidia Szpyrkowicz.

2. - A comparative study of platinised titanium and niobe/synthetic diamond as anodes in the electrochemical treatment of textile wastewater by Anastasios Sakalis. Chemical Engineering Journal - CHEM ENG J 01/2006; 119(2):127-133. DOI:10.1016/j.cej.2006.02.009

3.- Bechtold T. Cathodic decolourisation of textil waste water containing reactive dyes using a multicathode elctrolyser. Journal of chemical Technology and Biotechnology, 76 pp 303-311, 2001.

4.- Evaluation of a novel electrochemical pilot plat process for azodyes removal from textile wastewater, Chemical Engineering Journal, Volume 111, Issue 1, 1 July 2005, Pages 63-70.
Numerical Simulation of the Primary, Secondary and Tertiary Potential Distribution on Porous Cathode in a Flow-through Packed Bed Reactor. Influence of Thickness, Concentration and Hydrodynamics in Porous Media
Authors: Rivera Fernando Felipe , Nava José Luis
Published: February 2020

Packed bed electrodes can be used for electrochemical recovery of heavy metals from a variety of industrial and laboratory model solutions. The packed bed electrode forms a porous flow-through (Figure 1) configuration providing large surface area usually depleting the concentration of several metal ions below 0.1 ppm. For design porpoises of these electrodes, it is necessary to study the influence of geometry (cathode thickness), flow rate and concentration on potential distribution.

Numerical simulations of primary, secondary and tertiary current distributions on the porous cathode of a packed bed electrochemical reactor (Figure 1) were calculated. For primary and secondary current distribution, Laplace equations with its respective boundary conditions (constant potential for primary current distribution and charge transfer kinetics described by a Tafel approximation in secondary current distribution) were evaluated using the finite element method. For tertiary current distribution, the influence of hydrodynamics was taken in account, considering Navier-Stokes model with Brinkman extension for porous media. Once Brinkman equations was solved and local velocity distributions were obtained, local mass transfer coefficients were evaluated by means of following relationship:

Kma=cvb

where Km
is local mass transport coefficient, a is the specific area, v is local velocity, c and b are empirical constants taken from literature.

The effects of flow rate, ion concentration, matrix conductivity and thicknes on the distribution of current on porous cathode are analyzed. Results of current distribution obtained by Nava et. al 2008 [1] enable comparisons with the simulations.

References: [1] J.L. Nava, M.T. Oropeza, C. Ponce de León, J. González-García, A.J. Frías-Ferrer. Hydrometallurgy, 91, 2008, 98-103
Synthesis and Evaluation of High Surface Area Carbon Porous Media for Hydrogen-Bromine Fuel Cell
Authors: Yarlagadda Venkata , Nguyen Trung Van
Published: February 2020

The active surface area of the carbon electrode plays a significant role in optimizing the performance of a H2-Br2 fuel cell. The active surface area of the porous carbon media used as electrodes for the bromine reactions in a H2-Br2 fuel cell is quite low. A common approach to increase the active surface area for the bromine reactions is to use multiple layers of these porous carbon media. While this approach increases the active surface area, it also increases the thickness and diffusion pathway for the reactants and products of the reactions and could lead to mass transport limited performance at higher current densities. An alternate approach to increase the active surface area without affecting the transport related morphological properties like porosity and tortuosity of the electrode is to grow nanotubes directly onto the electrode fiber surface to create high active surface area. This presentation will discuss the synthesis and characterization of this carbon nanotube-based material and its performance as a bromine electrode in a H2-Br2 fuel cell

Acknowledgements

This work was funded by NSF through grant number EFRI-1038234 and DOE/ARPA-E under award number DE-AR0000262.