Effects of sputtering pressure on the characteristics of lithium ion conductive lithium phosphorous oxynitride thin film

Lithium phosphorous oxynitride(Lipon) thin films as a lithium ion conductive electrolyte were prepared by radio frequency reactive sputtering in N₂ plasma. The properties of the amorphous Lipon solid electrolyte were investigated as a function of N₂ pressure during reactive sputtering. The ionic conductivity and the electrochemical stability of Lipon thin films improved drastically as the N₂ pressure decreased. The ionic conductivity closed to 10⁻⁶ S cm⁻¹ and obtained a stability window of 1.0–5.0 V with an N₂ pressure of 5 mTorr, where the number of nitrogen bonds between the phosphate groups were more than those formed at higher pressure. It was possible to fabricate the Li//LiCoO₂ complete thin film battery using this Lipon solid electrolyte, which exhibited excellent discharge characteristics close to the theoretical capacity (ca. 69 uAhcm⁻²−um⁻¹) and showed a considerably high rate capability.     

High‐sensitivity PEA system with dual‐polarity pulse generator

The pulsed electroacoustic (PEA) method has been widely used to observe space charge distributions in various solid dielectric materials. The sensitivity of the conventional PEA system is around 1C/m³. When the charge density is less than 1C/m³, however, it is difficult to obtain an accurate result because the signal due to the Maxwell stress becomes comparable with the signal to be measured. The Maxwell stress is generated by applying the pulsed electric field to the dielectrics, and independent from the existence of either induced charges by DC bias voltage or internal charges. In order to eliminate the influence of the Maxwell stress, we have developed a new PEA system with a dual‐polarity pulse generator. The system allows measurement space at a charge density of around 0.03C/m³. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 1– 7, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20496     

Current‐mode wave field programmable analogue arrays

A new configurable analogue block (CAB), the key element in the design of field programmable analogue arrays (FPAAs), is introduced in this paper. This CAB is based on wave equivalents of the passive elements and it is easily reconfigurable resulting in very simple and versatile FPAA structures. The proposed topology employs a minimum number of switches in the signal path due to the absence of the interconnection network required in other FPAA structures, and thus an improved performance is achieved in comparison with the already introduced corresponding programmable configurations. Copyright © 2008 John Wiley & Sons, Ltd.     

The development of novel trivalent ion conducting solids and their application for gas sensors

An exceptionally high Al³⁺ ion conducting polycrystalline solid based on the NASICON type structure was successfully realized within the system (Al_xZr_1−x)_4/(4−x)Nb(PO₄)₃. The partial substitution of the smaller higher valent Nb⁵⁺ ion for Zr⁴⁺ helped stabilize and accommodate the mobile Al³⁺ ion into the NASICON like structure. The addition of boron oxide to the Al³⁺ ion conducting solid electrolyte, as a sintering additive, aided in the achievement of satisfactory mechanical strength and density for practical use. Environmental gas sensors were fabricated by combining the (Al_xZr_1−x)_4/(4−x)Nb(PO₄)₃ solid electrolyte with yttria stabilized zirconia (YSZ) and appropriate auxiliary electrodes. The Nernst-like electrochemical sensors demonstrated rapid and reproducible response to CO₂ and NOx, thereby promising excellent potential for environmental monitoring applications.     

Influence of microstructure on oxide ionic conductivity in doped CeO2 electrolytes

Doped ceria (CeO₂) compounds are fluorite type oxides, which show oxide ionic conductivity higher than yttria stabilized zirconia, in oxidizing atmospheres. As a consequence of this, considerable interest has been shown in application of these materials for `low (500^∘–650^∘C)’ temperature operation of solid oxide fuel cells (SOFCs). In this study, some rare earth (eg. Gd, Sm, and Dy) doped CeO₂ nano-powders were synthesized via a carbonate co-precipitation method. Fluorite-type solid solution were able to be formed at low temperature, such as 400^∘C and dense sintered bodies were subsequently fabricated in the temperature ranging from 1000^∘ to 1450^∘C by conventional sintering (CS) method. To develop high quality solid electrolytes, the microstructure at the atomic level of these doped CeO₂ solid electrolytes were examined using transmission electron microscopy (TEM). The specimens obtained by CS had continuous and large micro-domains with a distorted pyrochlore structure or related structure, within each grain. We conclude that the conducting properties in these doped CeO₂ systems are strongly influenced by the micro-domain size in the grain. To minimize the micro-domain size, spark plasma sintering (SPS) was examined. SPS has not been used to fabricate dense sintered bodies of doped CeO₂ electrolytes, previously; carbon from the graphite dies penetrates the specimens and inhibits densification. To overcome this challenge, and to be able to produce dense sintered bodies of doped CeO₂ of a grain size that minimizes the microdomain growth, a combination of SPS and CS methods were examined. Using this combined method we report that we were able to produce fully dense specimens with improved conductivity. This is correlated with a reduction in the size of the micro-domains. Consequently we conclude that the control of micro-domain size within the grain structure is a key component in the successful design of electrolyte materials with improved conductivity.     

10 years of materials research for solid oxide fuel cells at forschungszentrum jülich

In 1995 a fuel cell program was established at Forschungszentrum Jülich (FZJ) to combine various and independently existing activities on generic fuel cell research. As of this year, the materials development as well as the component manufacturing was focused on anode-supported cells. This contribution reviews the investigations on many materials and the fabrication processes applied for anode substrates, anodes, electrolytes and cathodes. Continuous effort on each of the components resulted in a steady progress in quality, size and performance of the solid oxide fuel cells (SOFCs). The electrochemical performance of anode-supported cells (ASC) with “conventional” electroceramic materials like lanthanum manganite as cathode, yttria-stabilized zirconia (YSZ) as electrolyte and a NiO/YSZ composite as anode and anode substrate was improved from about 0.15 W/cm² at 800^∘C to 1.2 W/cm² by optimization of processing and microstructure. Considering new perovskite materials like lanthanum cobaltite/ferrite as cathode, a power density of 1.4–1.7 W/cm² has been obtained. In addition to these strongly focused activities on ASC, FZJ has carried out R + D projects together with industrial companies for the planar and tubular electrolyte-supported cell systems (Siemens, Dornier). This review, however, also discusses efforts that were less successful for anode-supported SOFCs. As examples are mentioned here the lanthanum gallates as electrolyte materials or low-cost NiO/Al₂O₃ substrates, which are not dimensionally stable in fuel gas atmosphere.     

Interlaced switch boxes placement for three‐dimensional FPGA architecture design

Three‐dimensional (3D) field programmable gate array (FPGA) has evoked significant interest in wire‐length reduction for routing requirement. However, the complex design of the 3D switch boxes will limit the performance improvement and suffer from the area efficiency problems. This paper proposed a systematic graph model (SGM) for 3D switch boxes design to simplify the design process and reduce the storage memory for path programming. An interlaced 3D switch boxes and two‐dimensional (2D) switch boxes placement topology is also presented in this paper to design the 3D FPGA architecture for area efficiency purpose. The 3D place and route tool and TSMC 0.18‐µm CMOS process parameters are used to support building the experimental flow for verification. Performance evaluation shows that about 50% storage memory reduction can be obtained by using the proposed SGM‐based switch design approach. Additionally, compared with conventional architectures of 2D FPGA, the proposed scheme based on interlaced switch boxes placement approach can approximately achieve 20% delay‐power product improvement and 43% area‐delay product reduction. Copyright © 2010 John Wiley & Sons, Ltd.     

Characteristics on electrical resistance change of Ag doped chalcogenide thin film application for programmable metallization cell

Programmable Metallization Cell (PMC) Random Access Memory is based on the electrochemical growth and removal of nanoscale metallic pathways in thin films of solid electrolyte. This paper investigates the resistance change characteristics with applied voltage bias on Ag/Ge–Se and Ag/As–Se chlacogenide thin film structure and describes the electrical characteristics of PMC-RAM made from these materials following annealing at 150 °C. As a result, it was obtained that R _reverse/R _forward ratio which represent by reversible resistance change was about 10⁶, which ratio value can be get a high sensing margin when PMC-RAM detect the data. PMC-RAM technology promises to be non-volatile, low current and potentially, low cost for the next generation of nonvolatile memory application such as RFID chip to replace EEPROM.     

Single‐stage single‐switch PFC converter for wide‐input extreme step‐down voltage applications

This paper presents a new single‐stage single‐switch high power factor correction AC/DC converter suitable for low‐power applications (< 150 W) with a universal input voltage range (90–265 V_rms). The proposed topology integrates a buck–boost input current shaper followed by a buck and a buck–boost converter, respectively. As a result, the proposed converter can operate with larger duty cycles compared with the existing single‐stage single‐switch topologies, hence, making them suitable for extreme step‐down voltage conversion applications. Several desirable features are gained when the three integrated converter cells operate in discontinuous conduction mode. These features include low semiconductor voltage stress, zero‐current switch at turn‐on, and simple control with a fast well‐regulated output voltage. A detailed circuit analysis is performed to derive the design equations. The theoretical analysis and effectiveness of the proposed approach are confirmed by experimental results obtained from a 100‐W/24‐V_dc laboratory prototype. Copyright © 2011 John Wiley & Sons, Ltd.     

0.3‐V bulk‐driven programmable gain amplifier in 0.18‐µm CMOS

A new solution for an ultra low voltage bulk‐driven programmable gain amplifier (PGA) is described in the paper. While implemented in a standard n‐well 0.18‐µm complementary metal–oxide–semiconductor (CMOS) process, the circuit operates from 0.3 V supply, and its voltage gain can be regulated from 0 to 18 dB with 6‐dB steps. At minimum gain, the PGA offers nearly rail‐to‐rail input/output swing and the input referred thermal noise of 2.37 μV/Hz^1/2, which results in a 63‐dB dynamic range (DR). Besides, the total power consumption is 96 nW, the signal bandwidth is 2.95 kHz at 5‐pF load capacitance and the third‐order input intercept point (IIP₃) is 1.62 V. The circuit performance was simulated with LTspice. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and electrochemical properties of La<Subscript>1.0</Subscript>Sr<Subscript>1.0</Subscript>FeO<Subscript>4+δ</Subscript> as cathode material for intermediate temperature solid oxide fuel cells

Cathodic material La_1.0Sr_1.0FeO_4+δ for an intermediate temperature solid oxide fuel cell (IT-SOFC) was prepared via the glycine-nitrate process and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). XRD results showed that no reaction occurred between the La_1.0Sr_1.0FeO_4+δ electrode and Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte at 1000 °C. SEM results showed that the electrode formed good contact with the SDC electrolyte after sintering at 1000 °C for 2 h. The electrochemical properties of La_1.0Sr_1.0FeO_4+δ were measured using electrochemical impedance spectroscopy (EIS) and steady state polarization measurement. At 700 °C, the polarization resistance was about 3.90 Ωcm², and the lowest polarization overpotential was 57 mV at a current density of 55 mA cm⁻².     

Analysis of electric field induced by ELF magnetic field utilizing fast‐multipole surface‐charge simulation method for voxel data

This paper presents a fast‐multipole surface‐charge‐simulation method for calculating three‐dimensional Laplacian fields in voxel models. This method treats a surface of a voxel that has different inside and outside conductivities as a surface element of the indirect BEM (boundary element method). The main features of the proposed method are as follows. (1) An O(D²) performance in the memory capacity and operation cost is provided by applying the diagonal form fast multipole method (FMM), when the number of voxels is about D³. (2) The boundary matching is imposed by the continuity of the total flux passing through each element, which guarantees the solution globally satisfying Gauss's law; therefore the solution is globally stabilized. This method is successfully applied to calculate the electric field induced by an applied homogeneous ELF (extremely low frequency) magnetic field in a human head model that has 1 mm ×1 mm 1 mm voxel size. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 1–10, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20529     

Digitally programmable second generation current conveyor‐based FPAA

A novel fully differential digitally programmable current conveyor (DPCCII) is presented in this paper. The programmability of the proposed DPCCII is achieved using three‐bit MOS R‐2R ladder current division network. The DPCCII is used to realize a field programmable analog array (FPAA). The FPAA consists of seven configurable analog blocks arranged in a hexagonal form. The FPAA power consumption is 72.3 mW from 1 V voltage supply. A second‐order programmable universal filter is realized using the proposed FPAA as an application. All the circuits are realized and simulated using 90 nm IBM CMOS technology model under balanced supply voltage of ±0.5 V. Copyright © 2012 John Wiley & Sons, Ltd.     

Characteristics of thin film supercapacitor with ruthenium oxide electrode and Ta2O5+x solid oxide thin film electrolyte

We report findings related to a solid-state thin film supercapacitors (TFSCs) fabricated with ruthenium oxide electrodes and hydrogen doped tantalum oxide electrolyte in order to investigate a feasibility for solid oxide thin film electrolyte in all solid state micropower sources with hydrogen conducting electrolyte. The TFSCs in this study has a cell structure of RuO₂/Ta₂O₅/RuO₂/Pt. Radio frequency, off-axis r.f. sputtering deposition of a Ta₂O₅ thin film was performed on the bottom amorphous RuO₂ electrode which was deposited by an on-axis direct current reactive sputtering, within hydrogen atmosphere to enhance the concentration of mobile proton (H⁺) ions. Scanning electron microscopy (SEM) measurements reveal that the RuO₂/Ta₂O₅/RuO₂ hetero-interfaces have no inter-diffusion problems. Room temperature charge–discharge measurements with constant current clearly reveal typical supercapacitor behavior. Also, owing to the fast diffusion of H⁺ ions within the Ta₂O₅ lattice without any structural deterioration, the capacitance per volume of RuO₂/Ta₂O₅/RuO₂/Pt TFSCs was maintained to be constant during above 800 cycles. This result indicated that the solid oxide thin film has possibility as the solid proton conducting electrolyte for all solid state micropower sources.     

Nano vanadyl‐phthalocyanine crystals fabricated on KBr substrate

Vanadyl‐phthalocyanine (VOPc) thin films deposited on a KBr substrate by molecular beam epitaxy (MBE) consist of nano‐VOPc crystals epitaxially grown. The nano‐VOPc crystals acquire a square shape as a result of annealing at 150^°C. The size of the nano‐crystals is controllable by changing the conditions of MBE deposition and thermal treatment. The growth processes of nano‐crystals on the KBr substrate are elucidated experimentally and are shown to be closely related to strong interaction between the VOPc molecules and the KBr substrate. Their mechanisms can be explained in terms of surface diffusion of the VOPc molecules on the KBr substrate. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(2): 41–48, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20645     

A VERIFICATION OF NONVOLATILE PROGRAMMABLE LOGIC DEVICE

ABSTRACT

In this paper, Ferroelectric is introduced to nonvolatile programmable logic device (NVPLD). The device system is constructed, and the circuits of three main elements: switch cell, nonvolatile D flip-flop (NVDFF) and configurable logic block (CLB), are presented. Based on the circuit design, the feasibility of this device has been verified.     

Effect of composite electrode thickness on the electrochemical performances of all-solid-state li-ion batteries

Several ceramic half-cells with differing electrode composite thicknesses but identical formulations were assembled using the spark plasma sintering (SPS) technique, in order to conduct comparable investigations of their kinetic limitations. The SPS technique was used to assemble the composite electrode and the electrolyte together within a few minutes. NASICON-type Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) ceramic was used as solid electrolyte, as it offers high ionic conductivity (3 × 10^?4 S.cm^?1 at 25 °C) with a Li⁺ transport number of 1. LiFePO₄ active material was used as a model material; it offers an average flat potential of 3.45 V vs Li⁺/Li and a reasonably high theoretical capacity of 170 mAh.g^?1. Surface capacity values (from 0.8 to 3.5 mAh.cm^?2), which are proportional to electrode thickness, remained quite close to the initial values after more than 20 cycles, even for a 325 μm thick electrode (3.5 mAh.cm^?2). The overpotential in the flat plateau region was proportional to the current density used, which means that it was dependent only on the cell’s ohmic drop. Performances were not limited by the ion transport into the solid electrolyte and composite electrode volume - as in classical Li-ion batteries - since the transport number of LAGP is one. Therefore, very thick electrode-enabling batteries with high-surface capacity can be considered.     

Self‐sensing active magnetic bearings with zero‐bias‐current control

A zero‐bias‐current self‐sensing active magnetic bearing is proposed. One degree‐of‐freedom (DOF) of the rotor is controlled by a pair of electromagnets which are alternatively energized by the proposed circuit. The rotor position of the one DOF is measured by using both electromagnets: the nonenergized electromagnet also contributes to the position sensing. The proposed method gives good linearity in the position estimation. The controller of the magnetic levitation consists of a digital signal processor, DSP, which compensates the nonlinearity of the magnetic force and achieves good damping. In the experiment, the rotor can run at 45,000 min^‐1. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 69–76, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20616     

Solid Electrolyte Materials, Devices, and Applications

This paper outlines the development status, issues, and applications of several solid electrolyte electrochemical devices currently being developed by Ceramatec and its partners. Ceramatec and its commercial partner Air Products and Chemicals, Inc., (APCI) have successfully developed and demonstrated an electrochemical device that utilizes a ceria-based, solid electrolyte to separate oxygen from air [1, 2]. Other oxygen separator projects utilize ion transport membrane(s) (ITM) composed of mixed ionic and electronic conductors to transport oxygen ions across the membrane by means of a pressure differential driving force to generate high purity oxygen or a chemical reaction driving force to produce synthesis gas from methane (ITM Syngas).Ceramatec, in partnership with SOFCo, demonstrated kilowatt class solid oxide fuel cell (SOFC) stacks operating on a variety of fuels such as pipeline natural gas and reformed diesel. Ceramatec is presently working with Cummins and SOFCo to develop low cost modular fuel cells under the Department of Energys Solid-state Energy Conversion Alliance (SECA) initiative. Some of Ceramatecs other programs are focused on development of gallate electrolyte based fuel cells [3] and metallic bipolar plates [4] for lower temperature operation.     

High‐performance pMOSFETs with high Ge fraction strained SiGe‐heterostructure channel and ultrashallow source/drain formed by selective B‐doped SiGe CVD

The improvement of current drivability and short‐channel effect is very important for ultrasmall MOS device technology. SiGe‐channel pMOSFETs are one of the most promising devices because hole mobility in the SiGe layers is enhanced. In the previous work, it has been reported that Super Self‐aligned Shallow junction Electrode (S³E) MOSFETs formed by selective B‐doped SiGe CVD are effective for the suppression of short‐channel effect. In this paper, it is clarified that the (S³E) pMOSFETs with Si_0.65Ge_0.35 channel are realized not only with suppression of punch‐through due to the ultrashallow B‐diffused source/drain but also with enhancement of maximum linear transconductance due to the low parasitic resistance, compared to that with the Si channel fabricated by the same process conditions. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 46–50, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20597