bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Epitaxial Growth of Silicon Layer Using Batch-Type Equipment for Vertical Diode Application to Next Generation Memories
Authors: Lee Kong-Soo , Yoo Dae-Han , Yoo Young-Sub , Han Jae-Jong , Kim Seok-Sik , Jeong Hong-Sik , Kang Chang-Jin , Moon Joo-Tae , Park Hyunho , Jeong Hanwook , Kim Kwang-Ryul , Choi Byoungdeog
Published: April 2010

Vertical diodes for cross-point phase change memory were realized by selective epitaxial growth (SEG) technique using cyclic chemical vapor deposition method. H2/SiH4/Cl2 cyclic CVD system was introduced in batch-type vertical furnace equipement, replacing conventional single-wafer H2/dichlorosilane/HCl CVD system. It provided excellent capacity of 40 wafers per batch. Selectivity loss which is one of the most crucial features in SEG process for diode application was controlled with both the amount of SiH4 and Cl2 and the period of gas supply, and practical value of selectivity loss was confirmed to be less than 100 in 200-mm wafers. Structural and electrical properties of pn diodes were investigated, and cyclic SEG silicon diode showed more eligible electrical ability to current flow than that of poly-si in terms of forward current and ideality factor as well as lower reverse leakage current.
Atomically Flattening Technology at 850ºC for Si(100) Surface
Authors: Li Xiang , Suwa Tomoyuki , Teramoto Akinobu , Kuroda Rihito , Sugawa Shigetoshi , Ohmi Tadahiro
Published: April 2010

We demonstrate a low temperature flattening method for the 200-mm-diameter (100) orientation silicon wafers. By annealing in ultra pure argon ambient at 850ºC or above, atomically flat surfaces composed of atomic terraces and steps appear uniformly in the whole 200mm wafer. The width of atomic terrace changes with the off angle of wafer surface. It is found that with the off angle of 0.50º or below, only mono-atomic steps appear on the atomically flat surface, and the terrace widths are almost equal to the calculation values. Moreover, we have found using the vertical furnace the whole 200mm wafer surface can be atomically flattened in shorter time by increasing the argon gas flow rate or the annealing temperature. Furthermore, after annealing at 900ºC or below, there is no slip-line defect in the whole wafer. This low temperature flattening method is very suitable to be applied in the LSI manufacturing.
Impact of Work Function Optimized S/D Silicide Contact for High Current Drivability CMOS
Authors: Nakao Yukihisa , Kuroda Rihito , Tanaka Hiroaki , Isogai Tatsunori , Teramoto Akinobu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: April 2010

A formation process of the silicide/Si contact with low contact resistance in the source/drain (S/D) regions has been developed in order to reduce the S/D electrodes series resistance of MOSFETs. Er that has a low Schottky barrier height (SBH) for electrons and Pd that has a low SBH for holes were selected to n+- and p+-Si, respectively. The silicide formation process were carried out in N2 ambient from the Si surface cleaning before the metal depositions to the silicidation anneal in order not to expose metal and Si region so as to prevent the oxidation. W capping layer was formed on the Er surface for preventing Er from being oxidized, because the work function of Er is very low and it is very easily oxidized. These silicides were applied to Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), the improvement of the current drivability of n- and p-MOSFET was realized due to the reduction of the S/D electrodes series resistance.
Effect of In Situ Hydrogen Annealing on Dielectric Property of a Low Temperature Silicon Nitride Layer in a Bottom-Gate Nanocrystalline Silicon TFT by Catalytic CVD
Authors: Lee Youn-Jin , Lee Kyoung-Min , Hwang Jae-Dam , No Kil-Sun , Hong Wan-Shick
Published: April 2010

The dielectric property has great influence on characteristics of bottom-gate nanocrystalline silicon thin film transistor at low process temperature ({less than or equal to} 200°). For improving the quality of the gate dielectric layer, in-situ hydrogen annealing step in the silicon nitride deposition process was attempted in low process temperature by catalytic CVD system. The in-situ hydrogen annealing was effective in advanced field effect mobility and capacitance-voltage characteristic by decreasing the defects inside the SiNx film.
Aluminum-Doped Zinc Oxide Thin Films for Opto-Electronic Applications
Authors: Hirahara Naoki , Onwona-Agyeman Boateng , Nakao Motoi
Published: April 2010

Transparent conducting aluminum-doped Zinc oxide (AZO) thin films were prepared on glass substrates by rf magnetron sputtering technique using ZnO ceramic target in pure argon gas with different aluminum concentrations. The bandgap of the ZnO films slightly widens with increase in Al content and the lowest sheet resistance of AZO films with Al concentration of 4.25 atomic % was obtained. The effects of post-annealing treatment on structural, electrical and optical properties of the AZO thin films were investigated. Using AZO film with 4.2 at. % Al as the transparent electrode, a titanium dioxide based dye-sensitized solar cell was constructed and a solar to electrical energy conversion efficiency of 2.9 % was achieved under AM 1.5 solar simulated sunlight.
Investigation and Fabrication of Bottom Gate ZnO:Al TTFTs with Various Thicknesses of ZnO Buffer Layers
Authors: Lin Yung-Hao , Lee Hsin-Ying , Lee Ching-Ting
Published: April 2010

An Al doped ZnO (ZnO:Al) transparent thin film transistors (TTFTs) with various thickness of ZnO buffer layer sandwiched between gate insulator and channel ayer were deposited by a magnetron radio frequency co-sputter system. When the thickness of the buffer layer was 80 nm, the field-effect carrier mobility of the TTFTs was as high as 122.0 cm^2/V-s. Furthermore, the associated gate voltage swing was 0.24 V/decade, and the maximum state density was 2.69×10^11 eV^−1cm^−2. The on-to-off current ratio of the TTFTs with 80 nm-thick ZnO buffer layer was up to 5×10^7.
Epitaxial Growth of ZnO on LiAlO2 and LiGaO2 Substrates by Chemical Vapor Deposition
Authors: Chen Cheng-Huan , Yu Jun-Yi , Huang Teng-Hsing , Chang Liuwen , Chou Mitch
Published: April 2010

Epitaxial growth of ZnO on a tetragonal LiAlO2 (100) substrate and an orthorhombic LiGaO2 (100) substrate was examined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Results indicated that the crystal structure plays a major role on the orientation selection. The m-plane ZnO is favorable to grow on both substrates due to its low lattice mismatch to the substrates. However, the kinetic factor cannot be ignored on epitaxial growth. At low temperatures, limited adatom mobility can lead to the nucleation of crystals having a less favorable orientation, such as the c-plane ZnO on LAO or the random oriented ZnO on LGO. In addition, the morphology of the epitaxially grown crystals is affected by the anisotropy of the growth rate. For the c-plane ZnO, high anisotropy at low growth temperature results in rod shape crystals. At higher temperatures, the anisotropy is decreased and lateral growth leads to wineglass shape crystals.
ZnO Nanorod/p-GaN Heterostructured Light-Emitting Diodes Passivated Using Photoelectrochemical Method
Authors: Yan Jheng-Tai , Lee Ching-Ting
Published: April 2010

To fabricate the p-GaN/i-ZnO nanorod/n-ZnO nanorod (p-i-n) nanorod-heterosturctured light-emitting diodes (LEDs), i-ZnO and n-ZnO:In nanorod arrays were grown sequentially on a p-GaN layer. In order to passivate the non-radiatvie recombination centers at the nanorod sidewall, a thin Zn(OH)2 layer was directly grown on the ZnO nanorod using a photoelectrochemical method. Electrolumines¬cence emission at 386 nm was observed from the resultant LEDs. Furthermore, the light output intensity of the passivated nanorod-heterosturctured LEDs was much larger than that of the unpassivated nanorod-heterosturctured LEDs. The result demonstrated that Zn(OH)2 directly grown on the ZnO nanorod sidewall could passivate the non-radiative recombination centers effectively.
npn Heterostructural Optoelectronic Switch with Collector Confinement Layer
Authors: Guo Der-Feng
Published: April 2010

In order to achieve high optical sensitivity and low holding power, a wide-gap carrier confinement layer was introduced into the collector region of an npn-heterostructure optoelectronic switch. A similar device without the confinement layer was also fabricated to demonstrate the performance improvement. Both devices were found to have bistable electrical states: a high-impedance OFF state connected to a low-impedance ON state by a region of negative differential resistance (NDR). The functional characteristics were based on the avalanche multiplication.
Fabrication of IGZO Sputtering Target and Its Applications to the Preparation of Thin-Film Transistor Devices
Authors: Lo Chun C. , Hsieh Tsung-Eong
Published: April 2010

A hybrid of chemical dispersion and mechanical grinding process was developed to fabricate the mixture of nano-scale In2O3, Ga2O3 and ZnO oxide powders at the atomic ratio 1:1:2. As revealed by x-ray diffraction (XRD) analysis, sputtering target containing sole IGZO4 phase could be obtained by sintering the oxide mixture pressed in disc form at temperatures {greater than or equal to} 1300°C for 6 hrs. The IGZO target was then transferred to a sputtering system and the thin-film transistors (TFTs) containing amorphous IGZO channels were fabricated. Post-annealing at 300°C for 1 hr in air ambient was performed in order to improve the device performance. Electrical measurements indicated that the TFT samples with saturation mobility (μsat) = 14.7 cm2/V⋅s, threshold voltage (VTH) = 0.57 V, subthreshold swing (S.S.) = 0.45 V/decade and on/off ratio = 108 could be achieved.
Low-Resistivity and High-Transmittance Indium Gallium Zinc Oxide Films Prepared by Co-Sputtering In2Ga2ZnO7 and In2O3 Targets
Authors: Chang Heng-Jui , Huang Kuo-Ming , Chu Chen-Hsien , Chen Shang-Fu , Huang Tze H. , Wu Meng-Chyi
Published: April 2010

Indium gallium zinc oxide (IGZO) films are deposited on glass substrates by co-sputtering In2Ga2ZnO7 and In2O3 targets. The structural, electrical, and optical properties of the IGZO films have been discussed as functions of substrate temperature and rf power supplied to the In2O3 target (Prf, In2O3). From x-ray diffraction patterns, a halo peak around 34° is observed, which is attributed to the amorphous-like ZnkIn2O3+k structure. The electrical resistivity decreases with increasing substrate temperature and Prf, In2O3. The optimum resistivity is 7.16 × 10 -4 Ω-cm obtained at 175 ° substrate temperature and 20 W Prf,In2O3. The optical characteristics indicate that IGZO films are direct-transition type semiconductors. The optical band gap energy widens with increasing In2O3 content in the IGZO films. The optical transmittance of films deposited with 10-W Prf, In2O3 is higher than 99% in the wavelength region from 516 to 535 nm.
InGaN Light-Emitting Diode Structure on a Photoelectrochemical Treated GaN:Si Layer
Authors: Chen Kuei-Ting , Lin Chun-Min , Lin Chia-Feng
Published: April 2010

InGaN/GaN multiple-quantum-wells light-emitting diode (MQW-LED) structure was grown on a photoelectrochemical (PEC) treated n-type GaN:Si layer in deionized water. The PEC treated GaN:Si layer consisted of a nanoporous GaN:Si layer with a multiple-air-gaps (MAG) structure and the native GaOx layers that acted as submicro-masks for the epitaxial lateral overgrowth (ELOG) process. The photoluminescence spectrum has a 4.5nm wavelength blueshift phenomenon and a 2.0 times peak intensity enhancement in the MAG-LED structure (compared to a standard-LED) that is caused by a partially reduced piezoelectric field and an increasing light extraction process. The higher internal quantum efficiency and the higher light extraction process were observed in the MAG-LED structures by adding large volume of native GaOx layers and PEC treated multiple-air-gaps layers.
Dy3+ Emission from GaAlN Powder and Radio-Frequency Sputtered Thin Film
Authors: Tao Jonathan H. , McKittrick Joanna , Talbot Jan , Mishra Kailash C.
Published: April 2010

A three-step solution method previously used to synthesize AlN and GaN powders has been used to synthesize alloys of GaAlN. With the use of a stainless steel pressure vessel, single phase GaAlN powders were successfully synthesized. Powders of GaAlN activated with Dy3+ showed its related luminescence under cathodoluminescence. The emission intensity of Dy3+ increased when Al was incorporated in the GaN host. Radio-frequency sputtering of the same source powder did not produce a film with the same composition as the source material; only an epitaxial GaN film was deposited. X-ray diffraction was used to characterize the phase of the powder and thin film. As Dy3+ emission was observed for GaAlN:Dy3+ but not for GaN:Dy3+ powders synthesized by the same approach, this suggests that Al incorporation allows the luminescence of this rare-earth activator in GaN.
Surface Characterization of High Purity Metals of Silver and Nickel Electropolished with an Ionic Liquid
Authors: Abdel-Fattah Tarek M. , Loftis Jon Derek
Published: April 2010

Samples of high purity (>99.9% composition) silver and nickel were used in electropolishing treatments with an acid-free ionic liquid electrolyte prepared from vitamin-B4 as an eco-friendlily polishing solution. Voltammetry tests were utilized to determine the optimum conditions for electrochemical polishing. Digital microscopy provided an overall observation of the material interface between the treated and unpolished regions. Atomic force microscopy (AFM) revealed microscale effectiveness of each polishing treatment after chronoamperometry tests.
Influence of Carbon Nanotubes on the Electrodeposition of Copper Interconnects
Authors: Chowdhury Tamjid , Rohan J. F.
Published: April 2010

The electrochemistry of the co-deposition of Cu with carbon nanotube, CNTs is studied by voltammetry and chronoamperometry experiments. Electrochemical data shows CNTs have a slightly accelerating influence on the Cu electrodeposition when nafion was added in the bath as a surfactant of CNTs. The amount of CNTs in the deposit is up to 2% by weight. Kinetic data confirms that the addition of CNTs to the Cu baths increases the Cu exchange current density and decreases the equilibrium potential value. The electrical resistivity results show that at room temperature the resistivity of Cu/CNT composites film (2.47 μΩ-cm) is close to the resistivity of Cu film (2.15 μΩ-cm). A clear decrease of sample resistivity is observed with increasing anneal temperature upto 315ºC. The resistivity also increases when the concentration of CNTs is increased from 10 mg/l to 100 mg/l in the bath.
Effect of Functional Groups of Complexing Agents on the Performance of Cu CMP Slurry
Authors: Kim Yung Jun , Bae Jae Han , Kim Jae Jeong
Published: April 2010

Complexing agents in Cu chemical mechanical polishing (CMP) slurry have an important role for enhancing Cu removal rate. To understand the effects of complexing agents on the performance of Cu CMP slurry, selected complexing agents which have different functional groups were investigated. It was observed that the Cu dissolution rate was varied with the change of types and numbers of functional groups of complexing agents. By using UV-visible analysis, the changes of complex form with pH were monitored and expected reaction mechanisms were proposed. The effect of Cu oxide formation was also monitored by the coulometric reduction method (CRM) analysis. Based on CRM analysis, the evaluation of Cu oxide thickness which formed on the Cu surface during the dissolution was conducted and the relationships between formed Cu oxide thickness on the surface and Cu dissolution rate were discussed.
Effect of 5-phenyl-1H-tetrazole on Copper Dissolution for e-CMP
Authors: Cojocaru Paula , Magagnin Luca , Cavallotti Pietro L.
Published: April 2010

Among the planarization methods, electrochemical chemical mechanical polishing (e-CMP) is recognized as the most eligible for future applications in the electronic industry. The introduction of porous low-k dielectric materials into semiconductor devices requires the development of low downforce Cu e-CMP. It is well-known that inhibitors play a key-role in the e-CMP process. In this study, the effect of 5-phenyl-1H-tetrazole (PTA)) on e-CMP of copper was investigated.
(Invited) Through-Silicon Via Technology for 3D Applications
Authors: Philipsen Harold G. , Lühn Ole , Civale Yann , Wang Yu-Shuen , Sabuncuoglu Tezcan Deniz , Ruythooren Wouter
Published: April 2010

The development, characterization, and implementation of electrodeposition processes for IMEC's 3D-WLP flow on 200 mm wafer level is reported. The flow comprises of polymer-isolated Through-Silicon Vias (TSVs), realized on thinned wafers bonded to temporary carriers. Defect-free filling of 25 × 50 μm TSVs with copper was achieved, using IMEC ViaFill chemistry. Copper deposition and a subsequent tin plating in the same process step enables one to create μ-bumps, which then allow for the formation of interconnects between stacked dies. A method is proposed for studying the filling quality by preparing slanted cross-sections by mechanical polishing, which are subsequently inspected using optical microscopy. With this method, one can reveal defects at different levels inside the via and it has the advantage that a large number of TSVs are analysed. In addition to sectioning, an electrical characterization was done on both stacked dies and daisy chains and via chain connectivity is demonstrated.
Copper Electrodeposition Parameters Optimization for Through-Silicon Vias Filling
Authors: Delbos Elise , Omnès Laurent , Etcheberry Arnaud
Published: April 2010

Filling of Through-Silicon Vias (TSV) is governed, similarly to the well-known Damascene process, by several plating parameters and filling mechanisms. However, due to their larger dimensions, the diffusion of species into this particular type of via is becoming the main obstacle for the superfilling phenomenon generation. It is thus of prime importance to adjust the electroplating process parameters in order to take into account the TSV specificity. In this paper, the impact on the filling mechanism of four plating parameters - plating time, current density, wafer rotation and accelerator concentration - was investigated using two distinct methodologies: a fundamental analysis of the plating parameters on a gold planar electrode and their direct impact on the via filling.
Copper Plating for 3D Interconnects
Authors: Radisic Aleksandar , Lühn Ole , Vaes Jan , Armini Silvia , El-Mekki Zaid , Radisic Dunja , Ruythooren Wouter , Vereecken Philippe M.
Published: April 2010

We have explored different approaches to reducing plating time and overburden in electrochemical Cu fill of through-Si-vias for 3D stacked-integrated-circuits. We have already demonstrated (on beaker-level) that a thin Ta layer on top of the seed layer promotes Cu deposition in vias only, and when coupled with in situ fill-monitoring techniques has a potential to reduce both plating and chemical-mechanical-polishing (CMP) time. In this paper, we present first results on Cu plating and CMP of patterned Ta-capped 200 mm wafers with 5 µm x 25 µm vias.
High Speed Copper Electrodeposition for Through Silicon Via(TSV)
Authors: Kondo Kazuo , Suzuki Yushi , Saito Takeyasu , Okamoto Naoki
Published: April 2010

Copper electrodeposition in high aspect ratio via is one of the key technologies for 3D packaging. High speed copper electrodeposition is needed to achieve high TSV throughput. To inhibit the top surface of TSV, the ODT, was micro contact printed on the chip surface. ODT micro contact printing effectively inhibits the copper electrodepositon at the top surface. With SDDAC, V-shapes were formed in the via cross section and these V-shape shapes lead to bottom up via filling. Since the current density is lower for higher rotation disk rotation speed from the potential-current density curves, the copper electrodeposition is inhibited at the via openings. This leads to the V-shape cross sections. We succeeded to fill the 10 μm in diameter and 70μm in depth via within 37 minutes. This was achieved with shortening the off time to 100ms, ODT micro contact printing and adding 1mg/L of SDDACC additive.
Evaluation of Stability and Reactivity of Solutions by In Situ Transmittance in Electroless Deposition
Authors: Park Kyung Ju , Koo Hyo-Chol , Lim Taeho , Kim Jae Jeong
Published: April 2010

Evaluation of solution reactivity and stability is truly important to control the film properties and improve the solution lifetime in electroless deposition. The general electrochemical analysis for electrolyte evaluation has the limitations, such as complicacy, sensitivity and accuracy of system. In this study, verification of reactivity with SnPd colloid and confirmation of the effects of additives with varying their concentration in Cu ELD solution were conducted by means of in situ transmittance measurement. Particle size and morphology of Cu clusters were affected by not only reaction rate but also trait of additives. In Ag ELD solution, stabilizing performance was observed according to the tail groups of additive and the dependency of concentration was verified.
(Invited) Lithium Borates for Lithium-Ion Battery Electrolytes
Authors: Lex-Balducci Alexandra , Schmitz René , Schmitz Raphael W. , Müller Romek A. , Amereller Marius , Moosbauer Dominik , Gores Heiner J. , Winter M.
Published: April 2010

Plating-stripping and corrosion tests have been carried out at electrolyte solution containing lithium difluoro(oxalato)borate (LiDFOB) as a lithium salt. For comparison, also electrolytes containing other common borate salts have been investigated. After these tests, the same electrolyte solutions have been used in combination with lithium iron phosphate base electrodes at RT. The results of these studies are reported in this paper.
(Invited) Greener and Cheaper Batteries Containing Fluorine-Free Binder in Combination with Ionic Liquid Based Electrolytes
Authors: Lux Simon F. , Jeong Sang-Sik , Kim Guk-Tae , Passerini Stefano , Winter M. , Balducci Andrea
Published: April 2010

The performance of LiFePO4-based electrode containing CMC as binder in combination with the ionic liquids N-butyl-N-methylpyrrolidinium bis(trifluoromethansulfonyl)imide (PYR14TFSI) and 1-ethyl-3-methyl-1-H-imidazolium bis(trifluoromethansulfonyl)imide (EMIMTFSI) have been evaluated at RT. The obtained results in term on the specific capacity and the cycling stability are reported in this manuscript.
The Effect of Electrolyte Additives upon the Lithium Kinetics of Li-Ion Cells Containing MCMB and LiNixCo1-xO2 Electrodes and Exposed to High Temperatures
Authors: Smart Marshall C. , Bugga Ratnakumar V. , Gozdz Antoni , Mani Suresh
Published: April 2010

With the intent of improving the performance of lithium-ion cells at high temperatures, we have investigated the use of a number of electrolyte additives in experimental MCMB- LixNiyCo1-yO2 cells, which were exposed to temperatures as high as 80oC. In the present work, we have evaluated the use of a number of additives, namely vinylene carbonate (VC), dimethyl acetamide (DMAc), and mono-fluoroethylene carbonate (FEC), in an electrolyte solution anticipated to perform well at warm temperature (i.e., 1.0M LiPF6 in EC+EMC (50:50 v/v %). In addition, we have explored the use of novel electrolyte additives, namely lithium oxalate and lithium tetraborate. In addition to determining the capacity and power losses at various temperatures sustained as a result of high temperature cycling (cycling performed at 60o and 80oC), the three-electrode MCMB-LixNiyCo1-yO2 cells (lithium reference) enabled us to study the impact of high temperature storage upon the SEI film characteristics.
Synthesis and Electrochemical Studies on Li2CuSnO4 and Li2CuSnSiO6 as Negative Electrode in the Lithium Batteries
Authors: Shenouda Atef Y. , Liu Hua K.
Published: April 2010

Li2CuSnO4 and Li2CuSnSiO6 were prepared from their precursors compounds using Brij surfactant and a hydrothermal autoclave method. X-ray diffraction characterization revealed that the crystal structures of these compounds were tetragonal. Scanning electron microscope investigation showed the particle size morphology of Li2CuSnSiO6 is larger than that of Li2CuSnO4. Electrochemical impedance spectroscopy (EIS) explained that Li2CuSnO4 cell had higher charge transfer resistance (Rct = 2936Ω) than that of Li2CuSnSiO6 (38Ω). Furthermore, the reversible specific discharge capacity of the Li2CuSnSiO6 cell was 870 mAh/g in comparison with 780 mAh/g for the Li2CuSnO4 cell after 100 cycles, which is even higher than the theoretical value of Sn, 783 mAh/g.
(Invited) Long-Term Cyclability of Lithium Metal Electrodes in Ionic Liquid-Based Electrolytes at Room Temperature
Authors: Kim Guk-Tae , Appetecchi Giovanni B. , Montanino Maria , Alessandrini Fabrizio , Passerini Stefano
Published: April 2010

In this manuscript the results of extensive lithium plating-stripping cycling tests in asymmetric (Li/Ni) cells using ionic liquid-based electrolyte are reported. The electrolyte is composed by a binary mixture of N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (PYR14FSI) and lithium bis(fluorosulfonyl)imide (LiFSI) in a molar ratio of 9:1. The investigation clearly demonstrates that lithium metal electrode can reversibly cycle in this ionic liquid-based electrolyte with efficiency approaching 100%. Also, the LiFSI-PYR14FSI electrolyte was found to be highly compatible with lithium anodes in rest conditions even at high temperatures.
Nondestructive Depth Profiling of the Solid Electrolyte Interphase on LiFePO4 and Graphite Electrodes
Authors: Malmgren Sara , Rensmo Haåkan , Gustafsson Torbjorn , Gorgoi Mihaela , Edström Kristina
Published: April 2010

This study describes a method for non-destructive depth profiling of the electrode/electrolyte interphase in lithium-ion batteries. Photoelectron spectroscopy (PES) measurements using four different excitation energies in the 175 - 6900 eV range from two synchrotron sources (MAXlab and BESSY) was conducted on the surface of cycled LiFePO4 and graphite electrodes. Thus the surfaces were probed at four different depths in the 1-15 nm range without using sputtering, which is advantageous since sputtering has been shown to change the surface chemical composition. The results of this study suggest that the solid electrolyte interphase (SEI) on the cathode side, in addition to some salt products, also consists of some oxidized electrode components, while the SEI on the anode side mainly consists of solvent decomposition products, as expected. Finally, it is noted that we with this method can "see through the SEI layer" into the bulk also on the anode side.
A New Methodology for Evaluating the High-Power Behavior of a Li-Ion Battery Cell
Authors: Nyman Andreas , Zavalis Tommy G. , Elger Ragna , Behm Maårten , Lindbergh Göran
Published: April 2010

The internal sources of polarization are calculated and investigated for a graphite (MAG-10) | 1.2 M LiPF6 in EC:EMC (3:7 by weight) | LiNi0.8Co0.l5Al0.05O2 battery cell at SOC 40 and 80. A method is developed where the total polarization of the battery cell is split up into six polarizing subprocesses. The method involves two steps; the solving of an experimentally validated model that describes the dynamics of the battery cell during e.g. a hybrid pulse power characterization test and the use of the modeled cell's local potential, concentration profiles and local current density to calculate the internal losses. With this analysis the sources of polarization during an EUCAR test cycle are determined. The major factor limiting the performance is associated with the mass transport in the electrolyte.
A Study on the Cause of Deterioration in Float-Charged Lithium-Ion Battery
Authors: Tsujikawa Tomonobu , Yabuta Kahou , Matsushita Takashi , Arakawa Masayasu , Hayashi Koji
Published: April 2010

A lithium-ion battery composed of manganese spinel as the cathode material was tested by float charging. As a result, the capacity deterioration of the anode was greater than that of the cathode. The reduction of battery capacity is bigger than the capacity reduction supposed to be due to deterioration of the electrodes themselves, and it thought to be caused by disturbance of the lithium-ion balance, that is, a decrease in the amount of mobile lithium ions. Furthermore according to the results of the analysis of the anode, manganese is deposited on the anode, and it is thought that this deposition causes the disturbance of the lithium-ion balance. However, the capacity reduction cannot be explained by the manganese deposition alone; that is, it is supposed that a side reaction related to the deposited manganese that accompanies the loss of electric charge must be occurring at the anode as well.
Role of Corrosion Products in the Suppression of Atmospheric Corrosion of Aluminum and its Alloys
Authors: Dan Zhenhua , Muto Izumi , Hara Nobuyoshi
Published: April 2010

Atmospheric corrosion behaviors of aluminum and aluminum alloys were investigated through 18-month field exposure tests. The corrosion rates decreased with exposure time. The corrosion products formed in the first 3 months mainly consisted of basic aluminum chloride, basic aluminum sulfate and aluminum hydroxide. However, phase transformation took place during exposure and the corrosion products were composed of basic aluminum sulfate and aluminum hydroxide after 12-month exposure. The corrosion products played a key role of the suppression of the atmospheric corrosion on aluminum and its alloys. The membrane potential of basic aluminum sulfate in NaCl solutions indicated that this compound had a cation-selectivity. The sulfate-containing corrosion products prevent the penetration of chloride ions to protect the aluminum substrate. This is responsible for the observed decrease in corrosion rates after prolonged exposure to the atmosphere.
Effect of Temperature on the Corrosion Resistance of Stainless Steels in Polluted Phosphoric Acid
Authors: Ibáñez-Ferrándiz María , Blasco-Tamarit Encarnación , García-García Dionisio Miguel , Garcia-Anton José , Guenbour Abdellah , Bakour Sanae
Published: April 2010

The objective of the present work was to study the effect of the solution temperature on the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, the welded metal obtained by TIG (Tungsten Inert Gas) welding using a Nickel-base alloy (UNS N06059) as filler metal, and the Heat Affected Zone (HAZ) of the base metal. The materials have been tested in 5.5 M polluted phosphoric acid solution with 379 ppm of chloride ions and 2 wt% of H2SO4 at 25 ºC, 40ºC, 60ºC and 80ºC. Results demonstrated that the corrosion potential values shift to more anodic potentials as temperature increases. The corrosion current densities and the passive current densities increased with temperature. Open circuit potential values were located in the passive zone of the potentiodynamic curves, which means that the materials passivated spontaneously.
Automated Analysis of Electrochemical Curent Noise from Potentiostatic Conditioning of Passive Iron in Chloride-Containing Solutions
Authors: Soltis Jozef , Krouse Donal , Hodges Steve , Laycock Nicholas , Zavadil Kevin , Virtanen S. , Schmutz Patrick , Ryan Mary
Published: April 2010

We have demonstrated the applicability of a recently developed automated methodology for processing of electrochemical current noise through the analysis of current records from potentiostatic conditioning of high purity iron thin films in pH 8.4 borate buffer solutions containing low levels of chloride, at potentials below those required for stable pitting. The analysis precisely identifies all anodic current transients and allows us to distinguish carefully between those within the background noise level and those outliers that are considered to indicate the onset of pitting corrosion. A strong potential dependence was observed for the measured characteristics of both the background current noise and the identified pitting events.
Power Density Profile of Marine Biofilm Battery using a TiO2 Anode
Authors: Motoda Shin-ichi , Strom Matthew , Dexter Stephen C.
Published: April 2010

Ennoblement of corrosion potential of stainless steel exceeding 400mV (SCE) by formation of biofilm in seawater has been reported. This ennoblement of potential can be lead to the development of the battery by coupling with active counter electrodes. Recently, TiO2 coating appeared to shift the potential of base metal in active direction under irradiation of UV ray. This effect can be utilized as a non-sacrificial anode at the biofilm battery. The present work attempts to obtain the power density profile of the battery composed of biofilmed cathode and TiO2 coated anode.
In Situ Neutron Imaging Of Alkaline and Lithium Batteries
Authors: Riley Grant V. , Hussey Daniel S. , Jacobson David
Published: April 2010

We report on in situ tomographic (three dimensional) measurements of alkaline and lithium primary AA cells during constant current discharge to zero charge. The measurement spatial resolution was 150 um, and the relative uncertainty due only to counting statistics was of order a few percent for a one hour measurement time. The results for alkaline cells are consistent with the current understanding of discharge. The degree of anode utilization is seen to depend on discharge current, with a 0.5 A resulting in more complete utilization than that of a 1 A discharge. The lithium primary cell data has an additional systematic uncertainty due to beam hardening, which can be corrected. In these corrected images, the center of the jelly roll, which is initial empty, fills with cathode material and changes in the cell are similar for a 1 A and 0.1 A discharge rate.
Mg2+ Ion Behavior in Ionic Liquids
Authors: Sutto Thomas E. , Wong Tiffany , Taft Jenna , Duncan Teresa
Published: April 2010

The behavior of the Mg ion in ionic liquids is characterized in this paper. High ionic conductivity and electrochemical stability is observed for ionic liquids composed of a 1,2-dimethyl-3-n-R-imidazolium cation (R = propyl (MMPI) and butyl (MMBI)) and a bis(trifluoromethanesulfonyl)-imide (TFSI) anion containing Mg(TFSI)2. The ionic liquids containing the Mg ion are also used to create solid polymer gel electrolytes using PVdF-HFP. The ionic conductivity of the TFSI-based ionic liquids, in both liquid form and solid gel, ranges from 1-3 mS/cm at room temperature. Electrochemical measurements indicate that the Mg ion is readily intercalated and de-intercalated from graphite, with charge/discharge efficiencies typically above 80%. X-ray diffraction analysis indicates a difference of only 1 Aå in the c-axis expansion of the graphite when intercalated with the imidazolium cation or the Mg ion and the imidazolium cations. This indicates that co-intercalation of the Mg ion and the imidazolium cation is occurring.
Synthesis and Characterization of Polymerized Ionic Liquids
Authors: Sutto Thomas E. , Wong Tiffany , Taft Jenna , Duncan Teresa
Published: April 2010

Polymerized ionic liquids are prepared using a dibromoalkane reacted with 2 methyl imidazole. Two different dibromoalkanes are used, 1,5-dibromopentane and 1,6-dibromohexane. In order to increase the molecular weight of these two polymers, two different synthetic attempts were used to create poly-(2-methyl-1-pentyl imidazolium bromide and poly-(2-methyl-1-hexyl imidazolium bromide) with molecular weights of 7400 and 8900. Anion exchanges are performed to replace the bromide with hexafluorophosphate. These polymers are then doped with LiPF6 in a solution of acetonitrile which was subsequently drop cast. Ionic conductivity measurements indicate ionic conductivity above 0.01 mS/cm, with no liquid electrolyte present.
Effect of Predischarging on Electrochemical Properties of Positive Electrodes for Ni-MH Batteries
Authors: Inoue Hiroshi , Mizuta Touta , Higuchi Eiji
Published: April 2010

Effect of the pretreatment, discharging before the first charging, on electrochemical properties of Co(OH)2-coated Ni(OH)2 positive electrodes was investigated. High rate discharge ability (HRD) was increased with the pretreatment irrespective of the amount of the active material, and the positive effect of the pretreatment was more conspicuous as the amount of active material increased. The increase in charge transfer resistance (Rct) at DOCs less than 20 % was effectively suppressed by the pretreatment. A cyclic voltammogram and charge curve of the pretreated Co(OH)2-coated Ni(OH)2 positive electrodes showed that metallic Co was formed during the pretreatment, which was also confirmed by X-ray diffraction spectrum after the pretreatment, and could be easily oxidized to CoOOH via Co(OH)2 and Co3O4. These results suggest that the pretreatment assists the formation of a conducting network on the surface of the positive active material, leading to the improvement of HRD and Rct.
Modeling of Lithium Iron Phosphate Batteries by an Equivalent Electrical Circuit: Method of Model Parameterization and Simulation
Authors: Dong Trung K. , Kirchev Angel , Mattera Florence , Bultel Yann
Published: April 2010

Electrochemical impedance spectroscopy (EIS) measurements on Lithium Iron Phosphate (LiFePO4) batteries show a good correlation with the EIS of Li-ion batteries found in the literature, and thus the well-known equivalent electrical circuit (EEC) model of Li-ion batteries has been used to model LiFePO4 batteries. The model representation contains relevant parameters, including: inductance (L), ohmic resistance (R), migration of Li-ions through passive film (Rf//CPEf), charge-transfer kinetics (Rtc) at double layer (CPEdl). Full parameterization of EEC models is not possible only with the EIS method and, therefore, a combined frequency/temporal method has been developed. An excellent correlation between simulated and measured date was observed in wide state of charge (SOC) and charge/discharge current range.
Framework Doping of Cobalt into Layered Manganese Oxide for Improved Capacitive Behavior
Authors: Nakayama Masaharu , Suzuki Kazushi , Okamura Keigo , Athouël Laurence , Crosnier Olivier , Brousse Thierry
Published: April 2010

Anodic deposition of layered manganese oxides has been carried out at various bath temperatures in the presence of cobalt ions. Crystallinity of the layered Mn oxide increased with increasing the bath temperature. In the deposition of the layered Mn oxide, Co2+ ions were not involved at room temperature, while at 70°C the presence of Co2+ exhibited a catalytic current suggesting the formation of Mn and Co composite. Addition of Co2+ did not provide any new diffraction peaks but caused broadening of the peaks due to Mn oxide. This indicates the introduction of Co ions into the Mn oxide sheets. Doping of Co into the Mn oxide framework caused a drastic increase in the specific capacitance.
Artificial Neural Network for State-of-Charge Estimation of a Ni-MH Battery with a Photovoltaic Power System
Authors: Miyasaka Akihiro , Yamashita Akira , Shodai Takahisa
Published: April 2010

We developed a Ni-MH battery module and combined it with a photovoltaic panel as a hybrid power system for meteorological sensors. When the battery is charged with small current, such as less than 5 amperes (0.05 C), a conventional method on the state of charge (SOC) of the battery calculated from the summation of the current of the battery is inaccurate. For estimation of the SOC of the battery module, we therefore introduced an artificial neural network model in which the input data were the temperature and voltage of the battery module. It appears that the new estimation method is more accurate than the conventional one.
High-Voltage Dual Electrolyte Electrochemical Power Sources
Authors: Cheng Shaoan , Chan Kwong-Yu
Published: April 2010

A general method of operating a fuel cell or a battery with a positive electrode in acid and negative electrode in alkaline is discussed. This method can increase the operating voltage and power by as much as 50%. The alkaline electrolyte in the negative electrode compartment and the acidic electrolyte in the positive electrode compartment are separated by a bipolar membrane which provides the ionic conductivity between the two electrolytes and the continuous supply of protons and hydroxide anions via the water splitting reaction. The ability of a bipolar membrane to split water into the ions with low energy helps to achieve the cell voltage gained during discharge of the dual electrolyte power source.
Modeling Chemical Degradation of a Polymer Electrolyte Membrane and its Impact on Fuel Cell Performance
Authors: Coulon Romain , Bessler Wolfgang , Franco Alejandro A.
Published: April 2010

We present here an elementary kinetic model of the electrochemical phenomena occurring in a polymer electrolyte membrane fuel cell (PEFC). Chemical degradation of the Nafion® membrane is described through a combination of OH radical formation via Fenton's reaction and a radical mechanism of side chain decomposition. At the electrodes, the model is coupled to a description of the hydrogen oxidation reaction, the oxygen reduction reaction, and the hydrogen peroxide formation reaction at the anodic side. We establish a first feedback between the evolution of structural properties of the membrane and its transport parameters (i.e., proton conductivity) for a fully humidified fuel cell. We assess the influence of the chemical membrane degradation on the cell performance and on macroscopic properties of the membrane (i.e., sulfonate site concentration).
(2009 ECS Battery Division Technology Award) Development of Highly Durable PFSA Membrane for PEMFC under High Temperature and Low Humidity Conditions
Authors: Endoh Eiji
Published: April 2010

The world's first highly durable PFSA membrane for PEMFC have been developed, which can operate for more than 6,000 hours at 120ºC and 50% relative humidity (RH). The membrane is comprised of a newly invented composite polymer (NPC polymer), which has exceptional chemical stability against degradation caused by the hydroxyl radical even at 120ºC. This achievement has opened up a new era of operating PEMFC in the temperature range of near freezing to120ºC under low and high humidity conditions for an extended period of time.
Study on Structural and Electrical Properties of Ce0.5Zr0.5O2 for Applications in SOFC Anode
Authors: Desinan Stefano , Boaro Marta , Abate Chiara , Ferluga Matteo , De Leitenburg Carla , Trovarelli Alessandro
Published: April 2010

The redox properties of dense pellets of Ce0.50Zr0.50O2 have been investigated by temperature programmed reduction (TPR) (1023-1373K) and mild temperature oxidation (873K) cycles, X-ray powder diffraction technique (XRD), RAMAN spectroscopy and electrochemical impedance spectroscopy (EIS) have been used to characterize structural and conductivity modifications. The redox treatments promote both the reducibility at lower temperature and the electrical conductivity of this material. A gradual transition from a tetragonal to a pyrochlore cubic phase with the progress of reduction has been observed, while the nature of the phase after reoxidation depends on the temperature of reduction. The promotion of conductivity is correlated with the partial reordering of cationic lattice, but not specifically with the formation of the κ-phase.
Electrocatalytic Materials of NiCoRe Electrodeposited Alloy for Alkaline Water Electrolysis
Authors: Pashova Veselina , Mirkova Lidia , Monev Milko
Published: April 2010

The electrochemical behavior of electrodeposited Ni-Co-Re triple alloy is investigated in an alkaline medium and the kinetic parameters for the hydrogen evolution reaction are determined. The results are compared with those for electrodeposited Ni and Ni-Co alloy. The hydrogen evolution reaction occurs at a lower overpotential in the case of the triple alloy, which appears thereby as a promising electrocatalytic material for a negative electrode in an alkaline water electrolysis.
Synthesis and Characterization of Well Aligned Ru Nanowires and Nanotubes
Authors: Ponrouch Alexandre , Bichat M. P. , Garbarino Sébastien , Maunders C. , Botton Gianluigi , Taberna Pierre-Louis , Simon Patrice , Guay Daniel
Published: April 2010

Arrays of well aligned Ru nanowires and nanotubes were prepared by electrodeposition through porous anodic aluminum oxide membranes. It is shown that Ru nanowires are formed at low cathodic deposition overpotential, while nanotubes are prepared at higher cathodic overpotential. The inner diameter of the nanotube can be controlled by the deposition potential, and it varies from 0 to 70% of the outer diameter as the deposition potential is changed from -0.30 to -0.45 V vs SCE.
Fabrication of Nanogap Electrodes using Electrodeposition Process
Authors: Kobayashi Chiaki , Yoshida S. , Saito Mikiko , Wakayama Yutaka , Homma Takayuki
Published: April 2010

Laterally-enhanced growth of Au using electrochemical deposition from an electrode onto SiO2 surface modified with organic molecules for fabrication of nanogap electrodes was investigated. After modifying the SiO2 surface with self-assembled monolayers (SAMs) or dendrimer, electrodeposition was carried out and the enhanced lateral deposition was observed from the edge of Au electrode onto the SiO2 surface. In order to analyze the surface states modified with SAMs or dendrimer, X-ray photoelectron spectroscopy (XPS) were conducted and the existence of the organic molecules and Au ions on the SiO2 surface was confirmed. It was suggested that the enhanced lateral deposition was induced by the adsorbed Au ions. Furthermore, we tried to measure the electrical property of phthalocyanine molecular wire using the gap electrodes. In order to improve the contact state between the wire and the electrodes, electrodeposition was applied. As a result, improvement of contact state was observed from Current-Voltage characterization.
Development of Large Area CoNi Alloy Electrodeposition Process for Stress Free Electroforming Mold
Authors: Lee Jung-Ki , Cho Si-Hyeong , Kang Hyung-Bum , Lim Hyun-Woo , Yoo Bong-Young , Park Jin-Goo
Published: April 2010

A 140mm CoNi alloy stamp for NIL was fabricated from a nano Si mother mold by using stress free electroforming method. CoNi alloys were electrodeposited from cobalt-nickel chloride electrolyte to investigate the influence of flow velocity of plating solution on CoNi film stress. Co and Ni contents were able to be controlled by changing flow rates and bath concentration of CoCl2. The stress was reduced to 0 in the solution containing 0.008M CoCl2 at the flow velocity of 1 to 2 m/s. The process allows deposition of stress free CoNi alloys. The multiple duplication of a CoNi alloy stamp is possible without the consumption of costly Si mother stamp. Duplicated patterns on CoNi alloy stamp were compared with those of Si mother mold by using field emission scanning electron microscopy (FE-SEM) and atomic force microscophy (AFM).
The Synergic Impact of Saccharin and 2-butyne 1,4 Diol on the Electrodeposition of Nanocrystalline NiW Alloy
Authors: Zheng Min , Hilty R. D.
Published: April 2010

The synergic impact of saccharin and 2-butyne 1,4 diol (BT) on the microstructure and properties of electrodeposited nanocrystalline NiW alloy has been investigated. The morphology and grain structure were studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and X-ray diffraction pattern (XRD). The presence of BT only, or in combination with saccharin was found to have a significant impact on the microstructure of NiW alloy. The present study discusses the details of the impact additives used in electrodeposition may cause as regarded to internal stress.