bluuebunny/crossref_metadata_2025 huggingface dataset:
Impedance Spectroscopy Analysis of Ni/YSZ Interfaces Prepared by Liquid Precursor Deposition
Authors: Buyukaksoy Aligul , Birss Viola
Published: May 2015

In the present study, thin film Ni anodes, prepared by liquid precursor deposition on dense YSZ substrates, were analyzed by electrochemical impedance spectroscopy (EIS) in a humidified H2 environment at 500 to 700 °C, with the activation energy of 1.30 eV ascribed to the charge transfer reaction at the Ni – YSZ - gas triple phase boundary (tpb). For comparison, the same Ni precursor was infiltrated into a porous YSZ scaffold and was also then characterized by EIS analysis. A transmission line model was used to analyze the EIS data obtained from the infiltrated Ni-YSZ composite anodes, allowing the separation of the effects of ionic transport in the YSZ network and the impedance due to the electrochemical reaction at the tpb. The activation energy for the latter process was determined to be the same as for the model thin film Ni anode, suggesting that Ni/YSZ interfaces prepared in the form of Ni thin films on YSZ substrate and Ni-YSZ composites by the deposition of the same polymeric Ni precursor exhibit comparable impedance behavior.
Stabilization of Ni-YSZ Nanocomposite Anodes by Deposition of a Thin YSZ Overlayer
Authors: Buyukaksoy Aligul , Birss Viola
Published: May 2015

Lowering the operating temperatures of solid oxide fuel cells (SOFCs) to below 600 °C is projected to enhance the long term stability of these devices by slowing down thermally induced microstructural changes in the electrodes. To minimize the electrode resistance caused by the lowered operating temperatures, the fabrication of nanocomposite Ni-YSZ thin film electrodes with high triple phase boundary (tpb) lengths is a possible approach. However, these nanocomposite electrodes will still undergo microstructural changes that could cause performance degradation. Here, it is shown that the long-term stability of nanocomposite Ni-YSZ anodes can be enhanced by the deposition of a thin, poroous, YSZ coating on the outer surface of the Ni-YSZ electrodes, preventing Ni diffusion out of the pores followed by Ni particle formation. A degradation rate of 0.072 Ω·cm2/hour was observed for the standard Ni-YSZ nanocomposite thin film anode, whereas a much lower degradation rate of 0.011 Ω·cm2/hour was achieved after applying the YSZ coating.
(Invited) Reversible Solid Oxide Fuel Cell Development at Versa Power Systems
Authors: Wood Anthony , He Hongpeng , Joia Tahir , Brown Casey Cloudless
Published: May 2015

Versa Power Systems (VPS) is a developer of Solid Oxide Fuel Cell (SOFC) technology focused on SOFC stack development for commercial applications. In recent years VPS has been developing reversible SOFC (RSOFC) materials systems with a view to future commercial development of RSOFC stacks. VPS has demonstrated significant technical improvements in RSOFC materials technology in a relatively short timeframe, and has begun to test these at the stack level. This paper will provide an update of RSOFC activities including cell and stack testing in both steady-state electrolysis operation and operating with RSOFC cycles (fuel cell and electrolysis cycling).
Polybenzimidazole Membranes for Hydrogen Production in the Hybrid Sulfur Electrolyzer
Authors: Garrick Taylor Reed , Gulledge Alexander , Staser John A , Benicewicz Brian , Weidner John W.
Published: May 2015

The hybrid sulfur (HyS) thermochemical cycle has been studied as a means to produce large quantities of clean hydrogen at higher efficiencies than those possible from water electrolysis. Unfortunately, perfluorosulfonic acid polymers (e.g., Nafion) studied previously in SO2-depolarized electrolyzers for the HyS process suffer from poor proton conductivity at high acid concentrations. Therefore, alternative membranes are needed to obtain high efficiency in the electrolyzer used in the HyS process. Recent studies have shown that the HyS electrolyzer can operate with sulfuric acid-doped polybenzimidazole membranes, which have good proton conductivity when in contact with concentrated acid. Here we show model results that indicate s-PBI membranes can operate at up to 160°C at similar acid concentrations, which can reduce kinetic resistance and should improve overall system efficiency.
(Invited) Optimizing Electrocatalyst Selectivity for CO2 Reduction over H2 Evolution
Authors: Peterson Andrew A.
Published: May 2015

The electrocatalytic reduction of CO2 to fuels or chemicals is an attractive alternative to fossil- or biomass-based feedstocks. However, since the reduction typically requires protons in the reaction pathway, the evolution of H2 is a common side reaction; in practice H2 often dominates the observed products. In the current work, ways in which the selectivity between these two reactions can be understood and optimized are presented. First, it is shown that the identification and optimization of the expression of active edge sites in nanostructured Au catalysts for CO evolution results in catalysts with extremely high selectivities and mass activities at low overpotentials. Second, it is shown that the reactive state of the catalyst surface can have a strong steering effect on the selectivity. Fundamental adsorbate–adsorbate interactions drive the reactivity and selectivity across more reactive catalyst surfaces, and it is shown that in the example cases of Cu and Mo catalysts, the interaction can have opposite qualitative trends.
Electrochemical Reduction of CO2 Using Bi-Layer Cu2O Electrodes
Authors: Bugayong Joel , Griffin Gregory L
Published: May 2015

We examine the influence of electrode preparation on product selectivity during the electrochemical reduction of CO2 using electrodes prepared by electrochemical deposition of Cu2O onto various supports. In all cases, electrodes prepared using electrodeposited Cu2O layers produce higher C2H4/CH4 ratios than those observed using metallic Cu foils. The highest ratio for C2H4/CH4 products is observed using a bi-layer electrode prepared by electrodeposition of Cu2O onto a previously oxidized Cu foil. The implications of these results for understanding the reaction mechanism of CO2 electroreduction are discussed briefly.
Electro-Catalytic and Fuel Cell Studies in an Internal Reforming Iso-Octane Fed SOFC Using Cu/CeO2 Composites As Anodic Electrodes
Authors: Al-Musa Abdullah Abdulaziz , Al-Saleh Mohammed , Al-Zahrani Ayman , Kaklidis Nikolaos , Marnellos George
Published: May 2015

The internal reforming of iso-octane is examined in a solid oxide fuel cell of the type Cu-CeO2/YSZ/Pt. The results show that i-C8H18 is efficiently reformed by H2O to syngas over Cu/CeO2 composites, free of carbon deposits. Apart from iso-octane reforming, the products distribution at open circuit conditions is also influenced by the associated i-C8H18 thermal cracking and catalytic decomposition reactions as well as by the reverse water gas shift and methanation reactions. At closed circuit operation, the prevailing reactions are related to the electro-oxidation of H2 and CO and the co-electrolysis of H2O and CO2, at anodic and cathodic polarization conditions, respectively. AC impedance spectroscopy studies revealed that the cell and electrode resistances are substantially decreased with increasing temperature leading consequently to higher maximum power densities (12.6 mW/cm2, 850oC). The diffusion of charged and/or neutral species at the electrode surface is possibly the rate limiting step during fuel cell operation.
(Invited) Heterogeneous Nano- to Wide-Scale Co-Integration of Beyond-Si and Si CMOS Devices to Enhance Future Electronics
Authors: Thean Aaron , Collaert Nadine , Radu Iuliana P. , Waldron Niamh , Merckling Clement , Witters Liesbeth , Loo Roger , Mitard Jerome , Rooyackers Rita , Vandooren Anne , Verhulst A. , Veloso Anabela , Yakimets D. , Bao T. Huynh , Chiappe Danielle , Vaysset A. , Zografos O. , Caymax Matty , Huyghebaert C , Barla Kathy , Steegen A.
Published: May 2015

This paper overviews possibilities of heterogeneous material and device integrations base on selective area epitaxial growth. The options applicable at various scale from that of individual devices like FinFETs and Nanowires to wide areas of IIIV-Ge materials are described. Finally, multi-level integration of new 2-D crystals will be discussed as well.
(Invited) Si Nanowire Tunnel FETs for Energy Efficient Nanoelectronics
Authors: Zhao Qing-Tai , Richter Simon , Knoll Lars , Luong Gia Vinh , Blaeser Sebastian , Schulte-Braucks Christian , Schäfer Anna , Trellenkamp Stefan , Buca Dan , Mantl Siegfried
Published: May 2015

Experimental results of strained Si nanowire (NW) TFETs with tri-gate and gate all around (GAA) configurations are presented. Steep tunneling junctions formed by ion implantation into silicide (IIS) and low temperature annealing for dopant segregation allow to achieve subthreshold slope SS<60mV/dec. Improvement of the electrostatics by using GAA and smaller nanowires enhances the tunneling currents, lowers SS and lessens trap assisted tunneling (TAT). Pulsed I-V measurements demonstrate that suppression of TAT is the key to achieve steeper SS over a large range of drain currents. We also show that complementary TFET inverters and p-logic NAND gates can be operated at VDD=0.2V, demonstrating the great potential of TFETs for ultra-low power application.
(Invited) Monolithic Integration of III-V As- and P-Based Devices on Si through Direct MBE Growth and Using Lattice Engineered Substrates
Authors: Lubyshev Dmitri , Fastenau Joel , Liu Amy , Wu Ying
Published: May 2015

Monolithic integration of III-V material with Si have shown great potential to improve characteristics of integral circuits by increasing operational frequencies, reducing power consumption and, potentially, by replacing electrical interconnections with optoelectronic lines to increase data transfer speed. In this paper we discuss the integration of InP lattice parameter based quantum well field effect transistors and heterojunction bipolar transistors on Si via direct growth on Si substrates and using Silicon-on-lattice-engineered substrates. Main focus is on improvement of structural quality and reduction of epi-layer defects and dislocation density. The epi-layer transport properties and single transistor performance fabricated on Si was compared to references on InP substrates.
(Invited) Plasma Etching Technology Challenges for Future CMOS Fabrication Based on Microwave ECR Plasma
Authors: Izawa Masaru , Tanaka Motohiro , Yasui Naoki , Morimoto Michikazu
Published: May 2015

The dimensions of semiconductor devices are shrinking towards the nanometer range. More accurate surface reaction control is thus required in plasma etching on this scale. Time modulation (TM) of the radio-frequency (RF) bias, discharge, and gas injection processes has been investigated to improve both directional profiles and etch selectivity. Microwave electron cyclotron resonance (ECR) plasma was also shown to have affinities to pulse modulation and low ion energy processing. As examples, wiggling was improved using a pulsed discharge in a directed self-assembling (DSA) mask etch, and directionality was improved using gas pulsing technology in fin etching. In future MOS device fabrication, higher etch selectivity and more directional etch profiles are expected to be required and their accuracy requirements will reach the atomic level. A combination of pulsing technology (tri-time modulation, Tri-TM) and low bias power control at low pressure condition is considered as candidate technology for future device fabrication.
(Invited) Plasma Processes for Emerging Silicon-Based MEMS, NEMS and Packaging Applications
Authors: McNie Mark E
Published: May 2015

Plasma processes are important for emerging silicon-based micro-electro-mechanical systems (MEMS), nano-electro-mechanical systems (NEMS) and packaging applications. Typically every device has a customised process flow but synergies can be found as most are produced using a 2.5D approach comprising sequential deposition, lithography and etch cycles. Plasma processes are critical in enabling reproducible dry deposition and etch steps during the manufacturing flow of MEMS and NEMS devices but individual tools need the flexibility to address multiple different applications and process requirements. Increasingly plasma processes are also being adopted in nano-imprint lithography and bonding process steps. Plasma processes may be divided into the following broad families: chemical vapour deposition (CVD), atomic layer deposition (ALD), physical vapour deposition (PVD), surface functionalisation, etch (physically-driven) and etch (chemically-driven). The merits of each plasma technique and their application to emerging devices are discussed – including silicon etch processes that are at the heart of most MEMS and NEMS devices. Here trends are towards higher aspect ratios for enhanced performance and smaller footprint whilst maintaining throughput. Increasingly, large cavities are also being etched to realise membrane-based devices and in multi-wafer stacks where through silicon vias (TSVs) are emerging as a key technology for interconnect. At the research stage, the integration of ALD into MEMS is becoming more common whilst in NEMS devices are taking advantage novel combinations of processes and materials to realise new functions.
Solid State Incandescent Light Emitting Device Made of WOx Embedded Zr-Doped HfO2 High-k Stack on Si
Authors: Zhang Shumao , Kuo Yue
Published: May 2015

The phenomenon of white light emission from the WOx embedded Zr-doped HfO2 high-k dielectric MOS device has been investigated. The embedding of the WOx layer into the high-k stack increased the breakdown voltage due to the larger physical thickness. Light was emitted from many discrete nano dots due to thermal excitation of conductive paths formed from the dielectric breakdown process. The inclusion of the W component in the conductive path enhanced the emission of the red to IR portion of the light. The light intensity corresponds to the current density, which increases with the diving voltage. Judged from the light emission mechanism and optical properties, the light emission phenomenon is close to the blackbody emission. This kind of device can be applied to many products to take the advantage of its unique optical and thermal characteristics as well as the IC compatible fabrication process.
Process Optimization of CoSi2 Formation on P-Doped Poly-Si by Hot Wall-Based Rapid Thermal Annealing
Authors: Lee Jin Yul , Kim Hun Joo , Kim Eun Jeong , Song Han Sang , Yeom Seung Jin , Ishigaki Toshikazu , Kang Kitaek , Yoo Woo Sik
Published: May 2015

To achieve low resistivity contacts, the effect of annealing temperature and time on the resulting resistivity of CoSi2 contacts with P-doped poly-Si was investigated using a single wafer furnace-based (hot wall) rapid thermal annealing (RTA) system. The hot wall RTA resulted in significantly (>20%) lower sheet resistance (Rs) from the equivalent RTA process using conventional tungsten halogen lamp-based (cold wall) RTA systems over a very wide process window. Dopant (P) depth profiling results by secondary ion mass spectroscopy (SIMS) revealed that the P atoms in the CoSi2 film and at the CoSi2/P-doped poly-Si interface, redistribute very differently under different RTA conditions. The CoSi2 formation process was optimized utilizing characteristics of P pile-up near the CoSi2/P-doped poly-Si interface to suppress P depletion from the P-doped poly-Si layer.
Novel Buffered Magnetic Logic Gate Grid
Authors: Windbacher Thomas , Makarov Alexander , Sverdlov Viktor , Selberherr Siegfried
Published: May 2015

The nowadays performance limiting power dissipation due to leakage has become a critical burden. A simple way to reduce power dissipation is to shut down idle circuit parts. However, when hibernated circuit parts are activated again, their previous state must be recovered. In order to avoid energy and time consuming recovery cycles non-volatile elements must be added to realize the desired instant ON capability. In this work the combination of non-volatile magnetic flip flops and spin transfer torque majority gates to a novel buffered magnetic logic grid is proposed. The buffered logic grid features a highly regular structure, a small layout foot print, and it reduces the information transport due to its shared buffer. The realization of an easily concatenable one-bit full adder based on the novel buffered magnetic logic gate grid is explained.
Improved Structural and Electric Characterstics of Al/ALD-HfO2/Ge MOS Capacitor by Germanium Dioxide and Germanium Oxynitride as Interfacial Layer
Authors: Prasher Rakesh , Dass Devi , Vaid Rakesh
Published: May 2015

A 9.77 nm HfO2 thin film has been deposited on Ge substrate by ALD method. Rapid Thermal Oxidation (RTO) and Rapid Thermal Nitridation (RTN) have been used to form the gate interlayers (ILs) of GeO2 and GeON between them. High-frequency Capacitance-Voltage (C-V), Conductance-Voltage (G-V) techniques and Current-Voltage (I-V) measurement were used to obtain the electrical properties of the high-k MOS capacitor. By assimilating a thin GeON interlayer, excellent MOS capacitors with very small capacitance–voltage hysteresis and low gate leakage have been demonstrated. The results suggest that the physical and electrical properties (K, Dit, Qeff, etc) improved by rapid thermal annealing (RTA) in nitrogen ambient, which improves the interface properties of HfO2/Si due to the densification of HfO2 thin films. We found that the GeON/Ge gate stack exhibit a reduced equivalent oxide thickness (3.23 nm), interfacial trap density, effective oxide charges (Qeff), C–V hysteresis and leakage current.
(Invited) High Performance III-V-on-Insulator MOSFETs on Si Realized by Direct Wafer Bonding Applicable to Large Wafer Size
Authors: Takagi Shinichi , Kim Sang-Hyeon , Ikku Yuki , Yokoyama Masafumi , Nakane Ryosho , Li Jian , Kao Yung-Chung , Takenaka Mitsuru
Published: May 2015

MOSFETs using III-V channels with high mobility and low effective mass have been regarded as strongly important for obtaining CMOS under sub 10 nm technology nodes. One of the critical issues to realize III-V MOSFEs is to form high quality III-V films on large size Si wafers. In this paper, we present InGaAs-on-insulator (-OI) fabrication from an InGaAs layer grown on a Si donor wafer with a III-V buffer layer instead of growth on a InP donor wafer. This technology allows us to yield large wafer size scalability of III-V-OI layers up to the Si wafer size of 300mm with a high film quality and low cost. The high film quality has been confirmed by Raman and photoluminescence spectra. In addition, the fabricated InGaAs-OI transistors exhibit the high electron mobility of 1700 cm2/V s and uniform distribution of the leakage current, indicating high layer quality with low defect density.
(Invited) Advanced Semiconductor Devices for Future CMOS Technologies
Authors: Claeys Cor , Chiappe Danielle , Collaert Nadine , Mitard Jerome , Radu Juliana , Rooyackers Rita , Simoen Eddy , Vandooren Anne , Veloso Anabela , Waldron Niamh , Witters Liesbeth , Thean Aaron
Published: May 2015

Device scaling for higher performance and lower power consumption requires the introduction of advanced process modules, new materials new device architectures and finally even the use of alternative device operation principles compared to the standard MOS transistor. Several of these advanced devices will be discussed in view of their scalability and their potential for coping with the ITRS roadmap. Key performance parameters will be investigated.
Using the Wave Layout Style to Boost the Digital ICs Electrical Performance in the Radioactive Environment
Authors: Navarenho de Souza Rafael , Guazzeli da Silveira Marcilei , Gimenez Salvador Pinillos
Published: May 2015

This paper presents an experimental comparative study between the Metal-Oxide-Semiconductor Field Effect Transistors (MOSFET) manufactured with the Wave ("S" gate geometry) and the standard layout (CnM) considering the Total Ionizing Dose (TID) effects and taking into account that the devices were biased during the radiation procedure to emphasize the effects. Due to the special layout characteristics and the different effects of the bird’s beaks regions of the Wave MOSFET (WnM) compared to the conventional rectangular layout, this innovative layout proposal for MOSFETs is able to improve the device TID tolerance without adding cost to the Complementary MOS (CMOS) manufacturing process.
A Steep Subthreshold Swing Technique for Gate-All-Around SOI MOSFETs
Authors: Chen Chun-Yu , Lin Jyi-Tsong , Chiang Meng-Hsueh , Hsu Wei-Chou
Published: May 2015

A device design technique for silicon nanowire MOSFETs for low power capability beyond 10 nm technology node is demonstrated using 3D numerical simulation and physical analysis. The subthreshold kink effect enables the use of low supply bias without compromising performance. The kink-assisted methodology overcomes the fundamental and thermal voltage-limited subthreshold swing (SS).
Threshold Voltage Modeling for Dynamic Threshold UTBB SOI in Different Operation Modes
Authors: Itocazu Vitor Tatsuo , Sasaki Katia Regina Akemi , Manini Matheus Barros , Sonnenberg Victor , Martino Joao Antonio , Simoen Eddy , Claeys Cor
Published: May 2015

This paper presents an analytical model to determine the threshold voltage in Ultrathin Body and Buried Oxide Fully Depleted Silicon on Insulator (UTBB FD SOI) devices with Ground Plane (GP) implantation operating in three dynamic modes, simple Dynamic Threshold (DT), enhanced DT and inverse eDT mode. The analytical model is based on the Martino et
al model adding the quantum confinement effect. The results show that the analytical model proposed has a good agreement to experimental data.
(Invited) Si-Based Micro-Nanomechanics for Ultimate Sensing
Authors: Ono Takahito , Toda Masaya , Seo Yong-Jun , Inomata Naoki
Published: May 2015

Resonant sensors for ultimate sensing are developed. By scaling down, the sensitivity of a magnetic resonance force microscopy probe is improved, and three-dimensional imaging of radical density in a poly-10-(4-vinylbenzyl)-10H-phenothiazine particle is demonstrated at room temperature. Also resonant thermal sensor with a microchannel is developed and applied to detect heat from a single brawn fat cell.
(Invited) Comparative Simulation Study of InAs/Si and All-III-V Hetero Tunnel FETs
Authors: Schenk Andreas , Sant Saurabh , Moselund Kirsten , Riel Heike
Published: May 2015

Two different nanowire tunnel FETs, based either on the InAs/Si or the In0.53Ga0.47As/InP hetero-system, are investigated by device simulation. Variations of radius, equivalent oxide thickness, local doping, valence band offset, temperature, and the effect of trap-assisted tunneling on the sub-threshold slope and the on-current of the transistors are demonstrated.
(Invited) Challenges to Nano-Scale Device World
Authors: Balestra Francis
Published: May 2015

We are facing dramatic challenges dealing with future nano-scale devices, including performance, power consumption, new materials, device integration, interconnects, ultimate technological processes and novel functionalities, needing disruptive approaches and inducing fundamental tradeoffs for future ICs and Nanosystems. This paper will review recent advances and promising solutions for future high performance and ultra low power devices including 2D layers, TMDs, heterostructures and quantum wells using strain Si, Ge and III-V thin films, multi-gates, nanowires, CNTs, tunnel FETs and NEMS.
Crystallinity Improvement of Ferroelectric BiFeO3 Thin Film by Oxygen Radical Treatment
Authors: Imaizumi Fuminobu , Goto Tetsuya , Teramoto Akinobu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: May 2015

Oxygen radical treatment was applied to sputter-deposited BiFeO3 (BFO) thin film which is expected to be used for ferroelectric memories, sensors and solar cells. The oxygen radicals were produced by a microwave excited high-density Kr/O2 plasma. It was found from X-ray diffraction (XRD) that the crystallization temperature of the BFO film could be reduced to 350 °C by applying the oxygen radical treatment before the annealing. The (110) peak area which shows the crystallinity of BFO was by 4 times than that of the BFO film annealed at 500 °C without the oxygen radical treatment. From results of XRD and X-ray photoelectron spectroscopy (XPS), the stoichiometry was dramatically improved and this suggests that the oxygen radical treatment effectively creates the nucleation cites of BiFeO3 and reduces oxygen vacancy defects.
Influence of Substrate on Hafnium Silicate Metal-Insulator-Metal Capacitors Grown by Atomic Layer Deposition
Authors: Hutchinson B J , Teodorescu V S , Negrea R , Sheehan B , Carolan P , O'Brien S , Modreanu M , Pemble M E , Povey I. M
Published: May 2015

In this paper we report on the structural and electrical properties of hafnium silicate films grown by atomic layer deposition on a platinum bottom electrode. The results are compared to previously published results from our laboratory for an aluminum bottom electrode structure, with otherwise identical processing of the dielectric layer. The results demonstrate that the bottom electrode has a marked effect on both the structure and electrical properties of the resulting MIM capacitor. The previously reported films on aluminum were found to exhibit excellent electrical properties over a range of substrate materials and were consistent with hafnium silicate. In this study high resolution transmission electron microscopy (HRTEM) analysis and Raman spectroscopy indicate that on platinum the main crystalline phase is monoclinic HfO2 with a dielectric constant (k) value of ~18. Despite the crystalline nature of the HfO2 no hysteresis was observed in the capacitance voltage measurements. The scanning transmission electron microscopy (STEM) analysis also reveals the presence of nanoparticles, located primarily towards the lower platinum metal electrode at the HfO2 grain boundaries. Based on energy-dispersive x-ray spectroscopy (EDX) analysis the nanoparticles are consistent with silicon oxide inclusions.
Ultra-Low Temperature Flattening Technique of Silicon Surface Using Xe/H2 Plasma
Authors: Suwa Tomoyuki , Teramoto Akinobu , Goto Tetsuya , Hirayama Masaki , Sugawa Shigetoshi , Ohmi Tadahiro
Published: May 2015

In order to flatten any crystal orientation Si surface including Si-fin-structure and to introduce the flattening process just before the gate oxide formation in the latest LSI manufacturing process, it is strongly required that the flattening process is carried out at lower temperature. By introducing Xe/H2 plasma flattening at 400 oC just before the gate oxide formation, the breakdown field intensity (Ebd) was improved and Ebd fluctuation became much smaller than that of conventional.
FDSOI Suitability for Asynchronous Circuits at Sub-VT
Authors: Amat Esteve , Christmann Jean-Frédéric , Billoint Olivier , Miro Ivan , Beigne Edith
Published: May 2015

In this work, we explore the benefits of Fully Depleted Silicon-on-Insulator (FDSOI) devices to implement full-adders focused to operate at sub-threshold level. Their design based on asynchronous proposal shows lower energy consumption than their synchronous counterparts. Afterwards, the use of the FDSOI back-gate bias (VBB) allows an enhancement of sub-threshold circuit behavior, in contrast of other technology proposals. Their proper management could provide a temperature insensitive circuit behavior and larger variability robustness.
Synthesis of Metal Oxides/Graphene Nanocomposites for Applications in Lithium-Ion Battery
Authors: Nan Jiaqi , Dong Hongzhou , Li Guicun , Yu Liyan , Qin Yong , Dong Lifeng
Published: May 2015

Recently, lithium-ion battery has become a hot topic due to its high voltage, high energy density, and long cycle life. Traditional lithium-ion batteries employ graphite as anode materials. However, graphite suffers from several shortcomings, such as low reversible capacity and relatively low cycle life. In this study, graphene was used to replace graphite, and Co3O4 and SnO2 nanoparticles were synthesized on graphene surface. Comparative experiments clearly demonstrate that graphene anchored with Co3O4 or SnO2 nanoparticles synergistically prevented the degradation of graphene anode and the aggregation of Co3O4 and SnO2 nanoparticles during Li+ insertion and extraction process.
(Invited) Chemical Stability and Electronic Behavior of Atomic Layer Deposited Metal Oxide Thin Films
Authors: Strandwitz Nicholas C , Bao Bo , Correa Gabriela Calinao
Published: May 2015

Modification of semiconductor surfaces via the growth of metal oxide overlayers, particularly by atomic layer deposition (ALD), has become a topic of recent interest for surface passivation and chemical protection in semiconductor/liquid junctions. For example, in photoelectrochemical (PEC) water splitting, semiconductor surfaces typically must be protected with insulating or conducting layers that are stable in the electrochemical environment. Although thermodynamic stability of a solid phase in various environments can be readily assessed, complex phenomena such as film hydration and dynamic dissolution/precipitation can occur, impacting the efficacy of thin protective ALD films. We have examined the stability of the two of the most common ALD materials, alumina and titania, in a variety of environments. Film thickness was monitored after immersion in various liquid media. Our results indicate an increase in stability of the ALD films after post-deposition thermal treatment. Further, for alumina films in pure water, a restructuring occurs changing film density, thickness, and morphology. These results provide important guidelines for the applicability of ALD oxides as protective/passivating films on semiconductor electrodes for applications in sensing and photoelectrochemical water splitting.
An Attractive Wet Route for Nitriding III-Vs
Authors: Njel Christian , Aureau Damien , Gonçalves Anne-Marie , Etcheberry Arnaud
Published: May 2015

This paper presents an original electroless nitration process of InP surface in liquid ammonia (-55°C). The caution addition of phosphorus pentachloride in liquid ammonia leads to the formation of polyphosphazene and ammonium chloride. Both products are identified by thermogravimetric analysis and X-ray photoelectron spectrometry. The chemical surface modifications of InP are closed to those observed by electrochemistry since it leads to a polyphosphazene like film formation on InP. Moreover, the chemical stability of the surface is also demonstrated by XPS analyses. The electroless process can be attractive to the industry since no electrical connection (potential and current) are applied at the interface.
(Invited) Investigation of the Si/TiO2/Electrolyte Interface Using Operando Tender X-ray Photoelectron Spectroscopy
Authors: Lichterman Michael Frankston , Richter Matthias Hermann , Hu Shu , Crumlin Ethan J , Axnanda S , Favaro Marco , Drisdell Walter , Hussain Z , Mayer Thomas , Brunschwig Bruce , Lewis Nathan S. , Lewerenz Hans Joachim , Liu Z
Published: May 2015

Semiconductor-electrolyte interfaces allow for the creation of photoactive semiconductor systems that have band bending and other characteristics analogous to semiconductor-metal junctions (Schottky junctions). We demonstrate herein that XPS measurements can be obtained on a full three-electrode electrochemical system under potentiostatic control by use of tender X-rays to provide photoelectrons with sufficient kinetic energy to penetrate through a thin electrolyte overlayer on a portion of the working electrode. The response of the photoelectron binding energies to variations in applied voltage demonstrates that the XPS investigation works in an operando manner to elucidate the energetics of such interfaces.
Investigation of Photoelectrochemical Deposition of Zn(S,O) Via Nitrate Ions Reduction in the Presence of Thiourea
Authors: Gallanti Serena , Chassaing Elisabeth , Bouttemy Muriel , Etcheberry Arnaud , Lincot Daniel , Naghavi Negar
Published: May 2015

In this study, ZnO nanoporous layers have been deposited on Glass/Mo/Cu(In,Ga)Se2 substrate via nitrate ions reduction in presence of thiourea. The photoelectrochemical behavior of p-type semi-conductor Copper Indium Gallium Diselenide (CIGSe) has been studied in acidic medium for different pH values and different light intensities. Then, the effect of thiourea concentration between 0 and 1.0 M on the nitrate reduction in presence of zinc ion has been investigated by cyclic voltammetry in order to find the optimal potential for photoelectrodeposition. Results show that thiourea impacts the resulting photocurrent and the potential of the nitrates reduction. The photoelectrodeposited films have been characterized by Scanning Electron Microscopy, X-Ray Diffraction and X-Ray Photoelectron Spectroscopy. These analyses highlight that thiourea addition causes a change in film morphology, which is composed of well-crystallized ZnO with no sulfur incorporation. Moreover, thiourea seems to be an interesting additive to obtain nanoporous ZnO films on CIGSe.
(Invited) Preparation of GaSb Surface for Low Interfacial Trap Density MOS Capacitors
Authors: Chen Chen-Yu , Hsueh Wei-Jen , Chang Chao-Min , Hsu Hsien-Ming , Chyi Jen-Inn
Published: May 2015

The effects of i
n-situ and ex-situ surface treatments on the electrical properties of GaSb metal-oxide-semiconductor capacitors (MOSCAPs) are compared and investigated. The in-situ approach can provide a native oxide-free GaSb surface subsequent high-κ dielectric deposition. HfO2/Al2O3/p-GaSb MOSCAPs fabricated on an Sb-stabilized surface exhibit clear inversion at low frequency and good modulation of the Fermi level across the whole GaSb band gap. The interfacial trap density (Dit) extracted by the conductance method is about 7.6×1011 cm-2eV-1 near the valence band. As to the ex-situ process, the air-exposed GaSb samples are treated by hydrogen plasma at room temperature prior to dielectric deposition. The capacitance-voltage (C-V) characteristics and gate leakage currents are comparable to those of the MOSCAPs prepared by in-situ method. Dit near the valence as low as 6.0×1011 cm-2eV-1is obtained, indicating the feasibility of using GaSb p-channel MOSFETs for future complementary MOS integrated circuits.
Ag-Fe2O3 Heterostructured Nanoparticles as Photocatalysts under Visible Light Irradiation
Authors: Liu Shiben , Chen Yingjie , Dong Lifeng
Published: May 2015

In this study, Ag-Fe2O3 core-shell and heteromer nanocomposites and hollow Fe2O3 nanoparticles were synthesized and characterized. Among three types of nanostructures, Ag-Fe2O3 core-shell nanocomposite demonstrated the best photocatalytic performance due to its unique structure and broad UV-vis absorption spectrum. The findings will help us to further understand structure tuning capacity of nanocomposites and control their syntheses for photocatalytic applications.
Continuum Modelling of Silicon Diffusion and Activation in in0.53Ga0.47As
Authors: Aldridge Henry Lee , Lind Aaron Gregg , Law Mark E , Hatem Chris , Jones Kevin Scott
Published: May 2015

A continuum based-model of Silicon diffusion in ion-implanted InGaAs is presented. Several 5×1014 10keV Si+ implants into InGaAs were Rapid Thermal Annealed (RTA) at 750°C ranging from 10-40s. Box-like profiles characteristic of concentration-dependent diffusion were observed, similar to furnace anneals reported previously. Diffusivity extractions were carried out using FLOOPS (Florida Object Oriented Process Simulator), using point defect pairs, and Fermi level effects. Overall consideration of model fits and possible options for further development are suggested.
(Invited) The Effect of Thermally Induced Piezoelectricity on GaN HEMT Device Characteristics
Authors: Sengupta Jonah , McCluskey Patrick , Khanna Sumeer
Published: May 2015

GaN is increasingly being used in a wide variety of power electronic applications. The piezoelectric nature of GaN, however, can result in defect generation and can modify the electrical performance of power devices, especially AlGaN/GaN high electron mobility transistors (HEMTs). The cooling mechanisms used to cool the GaN can create thermal gradients that can exaggerate this piezoelectric effect. In this study, multiphysics finite element modeling was used to determine the thermal gradients, the resulting thermo-mechanical stresses, and the attendant changes in the electric fields resulting from piezoelectric interaction seen in the HEMT. Devices were then tested on a probe station to validate the results of the modeling. Evident drain and gate current and on-resistance degradation were observed after a 30 minute voltage and current stress was applied to the HEMT.
(Invited) Advanced Photon Management in Printed High-Efficiency Multijunction Solar Cells
Authors: Sheng Xing , Rogers John A.
Published: May 2015

Multijunction (MJ) solar cells have the potential to operate across the entire solar spectrum, for ultrahigh efficiencies in solar energy harvesting. We present materials and strategies of using printed MJ solar cell structures to bypass the challenges in conventional multijunction cell design. Firstly, microscale, quadruple junction (InGaP/GaAs/InGaAsNSb//Ge), four-terminal solar cells are fabricated by printing-based assembly with a refractive index matched interface material As2Se3. We obtain solar cells with measured efficiencies of 43.9% at concentrations exceeding 1000 suns, and modules with efficiencies of 36.5%. Secondly, we present a printed MJ cell architecture with low refractive indices as interfaces, providing further enhanced capabilities in photon recycling and photon extraction. Experiments demonstrate that thin-film GaAs devices printed on low-index substrates exhibit improved photon recycling, leading to increased open-circuit voltages, consistent with theoretical predictions. These concepts represent important aspects of design for solar cells that approach thermodynamic efficiency limits for full spectrum operation.
Early Detection of Lung Cancer Using High Electron Mobility Transistors
Authors: Sarangadharan Indu , Chu Chia Ho , Hsu Chen-Pin , Wang Yu-Lin
Published: May 2015

Mortality rate from lung cancer is high mainly because of the difficulty in diagnosis during early stage, resulting in delayed prognosis and therapy. Our focus is to develop a microelectronic sensor that can detect Lung cancer in early stage, which can be used by physicians to direct patients towards right prognosis. For achieving this, AlGaN/GaN HEMT has been used as an Immuno-FET, in which one of the common lung cancer biomarkers, CEA has been used as the target protein to bind with its antibody. This antibody-antigen binding results in excess surface charges that can be measured by the HEMT by applying a short duration pulse at the gate. The capacitive type of current obtained from HEMT, can provide us useful information and can depict dynamic mode of measurement. This method of measurement, combined with the high sensitivity of AlGaN/GaN HEMT can overcome the drawbacks of screening effect that occurs in solution with a high concentration of salt for traditional FET-based biosensors, and offer better limit of detection, sensitivity, repeatability and convenience.
A Semiconductor Gas System of Healthcare for Liver Disease Detection Using Ultrathin InN-Based Sensor
Authors: Kao Kun-Wei Arthur , Cheng Chin-Jen , Gwo Shangjr , Yeh J. Andrew
Published: May 2015

The gas sensor based on platinum-catalyzed ultrathin indium nitride (Pt-InN) was used to detect liver disease by sub-ppm ammonia (NH3) concentration variation in an ambient environment simulating exhaled human breath. Because the InN with strong surface electron accumulation extensively enhanced sensitivity, the NH3 gas sensor minimum detection limit is 0.2 ppm. Meanwhile, the sensor enables to distinguish slight deviation in NH3 concentration between 0.2 and 0.8 ppm that brings simple diagnosis of liver disease for portable and homecare clinical applications.
Dilute Hydrogen Sulfide Sensing Characteristics of a Pt/GaN Schottky Diode
Authors: Xiao Jian-Feng , Hsu Chen-Pin , Wang Yu-Lin
Published: May 2015

Hydrogen sulfide sensing characteristics of a Pt/GaN Schottky diode is the first time studied and demonstrated. The Ga-face GaN was grown on sapphire substrates by a metal-organic chemical vapor deposition (MOCVD) system. The main structure on the substrate is a Schottky contact, which is formed by Pt and GaN and separated from an Ohmic contact. The studied device exhibits a good sensitivity of hydrogen sulfide when the temperature is higher than 180°C and is able to detect diluted H2S close to 0.05 ppm at 200°C. Additionally, this device shows fast response time of around 10 seconds when the concentration of H2S is higher than 1ppm.
Should the sympathetic nervous system be a target to improve cardiometabolic risk in obesity?
Authors: Lambert Elisabeth A. , Straznicky Nora E. , Dixon John B. , Lambert Gavin W.
Published: May 2015

The sympathetic nervous system (SNS) plays a key role in both cardiovascular and metabolic regulation; hence, disturbances in SNS regulation are likely to impact on both cardiovascular and metabolic health. With excess adiposity, in particular when visceral fat accumulation is present, sympathetic activation commonly occurs. Experimental investigations have shown that adipose tissue releases a large number of adipokines, cytokines, and bioactive mediators capable of stimulating the SNS. Activation of the SNS and its interaction with adipose tissue may lead to the development of hypertension and end-organ damage including vascular, cardiac, and renal impairment and in addition lead to metabolic abnormalities, especially insulin resistance. Lifestyle changes such as weight loss and exercise programs considerably improve the cardiovascular and metabolic profile of subjects with obesity and decrease their cardiovascular risk, but unfortunately weight loss is often difficult to achieve and sustain. Pharmacological and device-based approaches to directly or indirectly target the activation of the SNS may offer some benefit in reducing the cardiometabolic consequences of obesity. Preliminary evidence is encouraging, but more trials are needed to investigate whether sympathetic inhibition could be used in obesity to reverse or prevent cardiometabolic disease development. The purpose of this review article is to highlight the current knowledge of the role that SNS plays in obesity and its associated metabolic disorders and to review the potential benefits of sympathoinhibition on metabolic and cardiovascular functions.
Endothelial disruptive proinflammatory effects of nicotine and e-cigarette vapor exposures
Authors: Schweitzer Kelly S. , Chen Steven X. , Law Sarah , Van Demark Mary , Poirier Christophe , Justice Matthew J. , Hubbard Walter C. , Kim Elena S. , Lai Xianyin , Wang Mu , Kranz William D. , Carroll Clinton J. , Ray Bruce D. , Bittman Robert , Goodpaster John , Petrache Irina
Published: May 2015

The increased use of inhaled nicotine via e-cigarettes has unknown risks to lung health. Having previously shown that cigarette smoke (CS) extract disrupts the lung microvasculature barrier function by endothelial cell activation and cytoskeletal rearrangement, we investigated the contribution of nicotine in CS or e-cigarettes (e-Cig) to lung endothelial injury. Primary lung microvascular endothelial cells were exposed to nicotine, e-Cig solution, or condensed e-Cig vapor (1–20 mM nicotine) or to nicotine-free CS extract or e-Cig solutions. Compared with nicotine-containing extract, nicotine free-CS extract (10–20%) caused significantly less endothelial permeability as measured with electric cell-substrate impedance sensing. Nicotine exposures triggered dose-dependent loss of endothelial barrier in cultured cell monolayers and rapidly increased lung inflammation and oxidative stress in mice. The endothelial barrier disruptive effects were associated with increased intracellular ceramides, p38 MAPK activation, and myosin light chain (MLC) phosphorylation, and was critically mediated by Rho-activated kinase via inhibition of MLC-phosphatase unit MYPT1. Although nicotine at sufficient concentrations to cause endothelial barrier loss did not trigger cell necrosis, it markedly inhibited cell proliferation. Augmentation of sphingosine-1-phosphate (S1P) signaling via S1P1 improved both endothelial cell proliferation and barrier function during nicotine exposures. Nicotine-independent effects of e-Cig solutions were noted, which may be attributable to acrolein, detected along with propylene glycol, glycerol, and nicotine by NMR, mass spectrometry, and gas chromatography, in both e-Cig solutions and vapor. These results suggest that soluble components of e-Cig, including nicotine, cause dose-dependent loss of lung endothelial barrier function, which is associated with oxidative stress and brisk inflammation.
Wenxin Keli versus Sotalol for Paroxysmal Atrial Fibrillation Caused by Hyperthyroidism: A Prospective, Open Label, and Randomized Study
Authors: Meng Zhaowei , Tan Jian , He Qing , Zhu Mei , Li Xue , Zhang Jianping , Jia Qiang , Wang Shen , Zhang Guizhi , Zheng Wei
Published: May 2015

We aimed to compare effectiveness of Wenxin Keli (WK) and sotalol in assisting sinus rhythm (SR) restoration from paroxysmal atrial fibrillation (PAF) caused by hyperthyroidism, as well as in maintaining SR. We randomly prescribed WK (18 g tid) or sotalol (80 mg bid) to 91 or 89 patients. Since it was not ethical not to give patients antiarrhythmia drugs, no control group was set. Antithyroid drugs were given to 90 patients (45 in WK group, 45 in sotalol group);131I was given to 90 patients (46 in WK group, 44 in sotalol group). Three months later, SR was obtained in 83/91 or 80/89 cases from WK or sotalol groups(P=0.762). By another analysis, SR was obtained in 86/90 or 77/90 cases from131I or ATD groups(P=0.022). Then, we randomly assigned the successfully SR-reverted patients into three groups: WK, sotalol, and control (no antiarrhythmia drug was given) groups. After twelve-month follow-up, PAF recurrence happened in 1/54, 2/54, and 9/55 cases, respectively. Log-Rank test showed significant higher PAF recurrent rate in control patients than either treatment(P=0.06). We demonstrated the same efficacies of WK and sotalol to assist SR reversion from hyperthyroidism-caused PAF. We also showed that either drug could maintain SR in such patients.
Nonexplosion and Pathwise Uniqueness of Stochastic Differential Equation Driven by Continuous Semimartingale with Non-Lipschitz Coefficients
Authors: Wang Jinxia
Published: May 2015

We study a class of stochastic differential equations driven by semimartingale with non-Lipschitz coefficients. New sufficient conditions on the strong uniqueness and the nonexplosion are derived ford-dimensional stochastic differential equations onRd(d>2)with non-Lipschitz coefficients, which extend and improve Fei’s results.