bluuebunny/crossref_metadata_2025 huggingface dataset:
Clarification and generalized quantifiers
Authors: Cooper Robin
Published: October 2013

Purver and Ginzburg introduce the Reprise Content Hypothesis (RCH) and use it to argue for a non-generalized quantifier approach to certain quantifiers. In previous work we contrasted their approach with an approach which employs a more classical generalized quantifier analysis. In the present paper we synthesize the two approaches and suggest that this gives us the best account of the dialogue phenomena associated with RCH.
Annotation upon Annotation: Adding Signalling Information to a Corpus of Discourse Relations
Authors: Taboada Maite , Das Debopam
Published: October 2013

We present an annotation effort that involves adding a new layer of annotation to an existing corpus. We are interested in how rhetorical relations are signalled in discourse, and thus begin with a corpus already annotated for rhetorical relations, to which we add signalling information. We show that a very large number of relations carry signals that identify them as such. The detailed, extensive analysis of signals in the corpus will aid research in the automatic parsing of discourse relations.
The new Algerian Digital Seismic Network (ADSN): towards an earthquake early-warning system
Authors: Yelles-Chaouche A. , Allili T. , Alili A. , Messemen W. , Beldjoudi H. , Semmane F. , Kherroubi A. , Djellit H. , Larbes Y. , Haned S. , Deramchi A. , Amrani A. , Chouiref A. , Chaoui F. , Khellaf K. , Nait Sidi Said C.
Published: October 2013

Abstract. Seismic monitoring in Algeria has seen great changes since the Boumerdes earthquake of 21 May 2003. Indeed, the installation of a new digital seismic network has resulted in a significant upgrade of the previous analog telemetry network. During the last four years, the number of stations in operation has increased substantially from 25 to 69, and 20 of these are broadband, 2 are very broadband, 47 are short period. 21 are equipped with accelerometers. They are all managed by Antelope software from Kinemetrics (US Cie), and they are all connected in real time and use various modes of transmission (e.g., satellite, internet, mobile phone). The spatial repartition of the stations now cover most of northern Algeria. In addition, 70 GPS stations have recently been added to this seismological network, most of them collocated with the seismological stations. Since the installation of the network, the records of local or distant events have improved significantly. The automatic processing of the data in a few minutes allows alert messages to be distributed to Civil Defense and other national authorities to react promptly to any emergency. The current strategy is to improve the data quality, to increase the density of the network by adding about 50 new stations, to reduce the processing time, and to reduce the time needed to send out an alert message. The result should be greatly improved network performance, which will lead to an effective early-warning system.
Cracking Codes and Launching Rockets
Authors: Paoletti Teo J.
Published: October 2013

This historically significant real-life application of a cryptographic coding technique, which incorporates first-year algebra and geometry, makes mathematics come alive in the classroom.
Delving Deeper: An Archimedean Balance: Polygons on the Head of a Pin
Authors: Worrall Charles
Published: October 2013

The author extends the idea of the “balancing point” of a triangle—its centroid—to other polygons.
Conceptual metaphorical mapping in chimpanzees (Pan troglodytes)
Authors: Dahl Christoph D , Adachi Ikuma
Published: October 2013

Conceptual metaphors are linguistic constructions. Such a metaphor is humans’ mental representation of social rank as a pyramidal-like structure. High-ranked individuals are represented in higher positions than low-ranked individuals. We show that conceptual metaphorical mapping between social rank and the representational domain exists in our closest evolutionary relatives, the chimpanzees. Chimpanzee participants were requested to discriminate face identities in a vertical arrangement. We found a modulation of response latencies by the rank of the presented individual and the position on the display: a high-ranked individual presented in the higher and a low-ranked individual in the lower position led to quicker identity discrimination than a high-ranked individual in the lower and a low-ranked individual in the higher position. Such a spatial representation of dominance hierarchy in chimpanzees suggests that a natural tendency to systematically map an abstract dimension exists in the common ancestor of humans and chimpanzees.
Multiple interfaces between a serine recombinase and an enhancer control site-specific DNA inversion
Authors: McLean Meghan M , Chang Yong , Dhar Gautam , Heiss John K , Johnson Reid C
Published: October 2013

Serine recombinases are often tightly controlled by elaborate, topologically-defined, nucleoprotein complexes. Hin is a member of the DNA invertase subclass of serine recombinases that are regulated by a remote recombinational enhancer element containing two binding sites for the protein Fis. Two Hin dimers bound to specific recombination sites associate with the Fis-bound enhancer by DNA looping where they are remodeled into a synaptic tetramer competent for DNA chemistry and exchange. Here we show that the flexible beta-hairpin arms of the Fis dimers contact the DNA binding domain of one subunit of each Hin dimer. These contacts sandwich the Hin dimers to promote remodeling into the tetramer. A basic region on the Hin catalytic domain then contacts enhancer DNA to complete assembly of the active Hin tetramer. Our results reveal how the enhancer generates the recombination complex that specifies DNA inversion and regulates DNA exchange by the subunit rotation mechanism.
Coherent Growth of AlN/GaN Short-Period Superlattice with Average GaN Mole Fraction of up to 20% on 6H-SiC(0001) Substrates by Plasma-Assisted Molecular-Beam Epitaxy
Authors: Kaneko Mitsuaki , Kikuchi Ryosuke , Okumura Hironori , Kimoto Tsunenobu , Suda Jun
Published: October 2013

To obtain a high-crystalline-quality AlN/GaN short-period superlattice with higher average GaN mole fraction, the effects of the thicknesses of AlN barrier and GaN well layers on the superlattice growth were investigated. Coherent growth with an average GaN mole fraction of 20% was realized by reducing the AlN barrier layer thickness to 8 bilayers (BL) while keeping the GaN well layer thickness at 2 BL. Further reduction in the AlN barrier layer thickness resulted in lattice relaxation and degradation of the crystalline quality. Grown layers with various well and barrier thicknesses were investigated by transmission electron microscopy, X-ray diffraction, and atomic force microscopy.
Metal–Organic Vapor Phase Epitaxy Growth of Embedded Gallium Nitride Nanocolumn for Reduction in Dislocation Density
Authors: Umeda Shinya , Kato Takahiro , Kitano Tsukasa , Kondo Toshiyuki , Matsubara Hiroyuki , Kamiyama Satoshi , Takeuchi Tetsuya , Iwaya Motoaki , Akasaki Isamu
Published: October 2013

The use of nanocolumn crystals is thought to be effective in producing a low-dislocation-density GaN layers. In this paper, we propose a metal–organic vapor phase epitaxial (MOVPE) growth method for producing uniform GaN nanocolumns using deep through-holes in a thick SiO2 selective growth mask. A SiO2 film with a thickness of 500 nm was deposited by sputtering on an AlN buffer layer/SiC substrate. A nanoimprinting technique was applied to produce dot openings. Then, dry etching with CF4 gas was carried out to form deep through-holes in the SiO2 film. In the second MOVPE growth, individual GaN nanocolumns coalesced into a planarized GaN layer, after thinning the SiO2 mask to 100 nm. A cathode-luminescence image of the GaN layer on a GaN nanocolumn template shows a low dislocation density of 1.3×108 cm-2, while that of a GaN layer directly grown on an AlN buffer layer shows a dislocation density of 9.4×108 cm-2.
Light Improvement of Near Ultraviolet Light-Emitting Diodes by Utilizing Lattice-Matched InAlGaN as Barrier Layers in Active Region
Authors: Lu Yu-Hsuan , Fu Yi-Keng , Huang Shyh-Jer , Su Yan-Kuin , Xuan Rong , Pilkuhn Manfred H. , Chen Ying-Chih
Published: October 2013

The effects of lattice-matched InAlGaN used as barriers in the active region were investigated in near ultraviolet light-emitting diodes (LEDs). By changing the thickness of InAlGaN barriers, it is observed that there exists an optimal thickness. Besides the better carrier confinement in the case of using thick barriers, the simulation results showed that hole distribution in the case of using wide barriers should also play a role in the improvement of optical performance. Hence, an excessive increment in the width of barriers will degrade the optical performance contrarily, owing to the accumulated stress and the difficulty in hole transport in the active region from thick barriers. In addition, the calculated energy bandgap of InAlGaN is higher than that of GaN, which is beneficial for increasing the capability of carrier confinement and simultaneously enhancing the radiative recombination. Under 100 mA, the light output power of the LED with 7.3-nm-thick In0.018Al0.09Ga0.892N barriers can be increased by 36% as compared with the LED with GaN barrier.
Comprehensive Classification of Near-Edge X-ray Absorption Fine Structure Spectra of Si-Containing Diamond-Like Carbon Thin Films
Authors: Kanda Kazuhiro , Niibe Masahito , Wada Akira , Ito Haruhiko , Suzuki Tsuneo , Ohana Tsuguyori , Ohtake Naoto , Saitoh Hidetoshi
Published: October 2013

Structural analysis by the measurement of carbon K-edge near-edge X-ray absorption fine structure (NEXAFS) using synchrotron radiation was performed on 23 types of silicon-containing diamond-like carbon (Si-DLC) film fabricated by various synthesis methods. In addition, elementary composition in the Si-DLC films was determined by the combination of Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA) using an electrostatic accelerator. In the C K-edge NEXAFS spectra of Si-DLC films, the σ* band shrunk and shifted to the lower-energy side, and the π* peak broadened with increasing silicon content in the Si-DLC film. The observed NEXAFS spectra of Si-DLC films were classified into four types.
Effects of Bipolar Pulse Poling on the Ferroelectric and Piezoelectric Properties of Tetragonal Composition Pb(Zr0.3,Ti0.7)O3 Thin Films on Microelectromechanical Systems Microcantilevers
Authors: Kobayashi Takeshi , Makimoto Natsumi , Suzuki Yasuhiro , Funakubo Hiroshi , Oikawa Takahiro , Wada Auyumi , Maeda Ryutaro
Published: October 2013

We have investigated the effects of bipolar pulse poling (pulse poling) on the crystal orientation, ferroelectric property and piezoelectric property of Pb(Zr0.3,Ti0.7)O3 (tetra-PZT) thin films integrated on MEMS-based microcantilevers. 1.9-µm-thick tetra-PZT thin films were deposited by the sol–gel technique and fabricated into piezoelectric microcantilevers by a MEMS microfabrication process. We have found that the suitable step for pulse poling in the MEMS microfabrication process is after the completion of all of the processes. We have optimized pulse poling voltage by using the fabricated piezoelectric microcantilevers. The volume fraction of the c-domain and remnant polarization of the tetra-PZT thin films increase with pulse poling voltage, while the piezoelectric constant -d
31 reaches its maximum at a pulse poling voltage of 50 V. The maximum piezoelectric constant -d
31 is estimated to be 50 pm/V.
Growth and Characterization of Ca2Al2SiO7 Piezoelectric Single Crystals for High-Temperature Sensor Applications
Authors: Hagiwara Manabu , Noguchi Hiroaki , Hoshina Takuya , Takeda Hiroaki , Fujihara Shinobu , Kodama Nobuhiro , Tsurumi Takaaki
Published: October 2013

The electrical properties of a piezoelectric single crystal of calcium aluminate silicate Ca2Al2SiO7 (CAS) were studied at elevated temperatures and its applicability to high-temperature pressure sensors was investigated. The CAS bulk single crystal was grown by the Czochralski method. The piezoelectric d
14 and d
36 constants were respectively evaluated as 6.04 and 4.04 pC/N by the resonance and antiresonance method. The temperature dependence of the piezoelectric constant was investigated at temperatures up to 500 °C. The electrical resistivity at 800 °C was on the order of 108 Ω·cm along both the crystallographic a- and c-axes. The measurement of direct piezoelectric response at 700 °C demonstrated that the CAS crystal could detect a pseudo-combustion pressure change of an automobile engine. Our observations suggest that CAS crystals are superior candidates for sensing pressure at high temperatures.
Fabrication and Characterization of (100),(001)-Oriented Reduction-Resistant Lead-Free Piezoelectric (Ba,Ca)TiO3 Ceramics Using Platelike Seed Crystals
Authors: Ichikawa Hiroki , Sakamoto Wataru , Akiyama Yoshikazu , Maiwa Hiroshi , Moriya Makoto , Yogo Toshinobu
Published: October 2013

The preparation of reduction-resistant (Ba,Ca)TiO3 ceramics as lead-free piezoelectric materials was studied. To improve their electrical properties, (100),(001)-oriented (Ba0.85Ca0.15)TiO3 ceramics were fabricated by the reactive templated grain growth method using a mixture of platelike CaTiO3 and BaTiO3 particles. The platelike CaTiO3 and BaTiO3 particles were prepared through a topochemical microcrystal conversion process using CaBi4Ti4O15 and BaBi4Ti4O15 plate-like precursor crystals. The 100 orientation degree of the grain-oriented (Ba0.85Ca0.15)TiO3 ceramics was 92%, as estimated by Lotgering's equation. In addition, 1 mol % Ba excess and 1 mol % Mn-doped (Ba0.85Ca0.15)TiO3 sintered bodies, which were sintered at 1350 °C in an Ar flow containing H2 (0.3%), had sufficient resistivity to allow the characterization of electrical properties. The ferroelectric and field-induced strain properties of the (Ba0.85Ca0.15)TiO3 ceramics, sintered in the reducing atmosphere, were markedly improved as a result of fabricating grain-oriented samples. The field-induced strain coefficient (estimated from the slope of the unipolar strain loop) of the nonreducible (100),(001)-oriented (Ba0.85Ca0.15)TiO3 ceramics reached 570 pm/V, which was higher than that of polycrystals (260 pm/V) with no preferential orientation.
Photocurrent Characteristics of Mn-Doped Barium Titanate Ferroelectric Single Crystals
Authors: Inoue Ryotaro , Ishikawa Shotaro , Kitanaka Yuuki , Oguchi Takeshi , Noguchi Yuji , Miyayama Masaru
Published: October 2013

We investigated the photocurrent characteristics of ferroelectric single crystals of nondoped barium titanate (BT) and Mn-doped barium titanate (Mn-BT). The introduction of 90° domain structures into the BT crystals markedly increased the photocurrent, which suggests that the separation of photoinduced carriers is significantly enhanced around 90° domain walls (DWs). The Mn doping led to a drastic increase in photocurrent, with a photon energy less than the band gap. Density functional theory calculations show that the large photocurrent observed for the Mn-BT crystals originates from the electron excitation from the O 2p valence band to the Mn eg defect level followed by carrier (hole) injection.
Enhanced Microwave Resonance Properties of Pseudo-Tungsten-Bronze Ba6-3xR8+2xTi18O54(R = Rare Earth) Solid Solutions Explained by Electron–Phonon Interaction
Authors: Wunderlich Wilfried , Ohsato Hitoshi
Published: October 2013

Microwave dielectrics consisting of pseudo-tungsten-bronze solid solutions form compositional ordering atx= 2/3 with the Ba6-3xR8+2xTi18O54(R= La, Nd, Pr, Sm, Eu, and Gd) formula. TheQfvalue of thex= 2/3 composition shows the highest value for Sm, but a discontinuity at Eu. When doping with heavier rare earth species, the crystal structure becomes unstable and needs stabilization with Nd. In this paper, we suggest for the first time that the electron–phonon interaction is responsible for this phenomenon. As the unit cells without Ba ions in the perovskite blocks caused tensile stress, the dielectric constant and dielectric losses increase by means of the ionic size of the dopant in the octahedral sites, but only when elements with a low electron–phonon interaction are used.
Twenty-Layer Optical Disc Fabricated by Web Coating and Lamination
Authors: Mikami Tatsuo , Mochizuki Hidehiro , Sasaki Toshio , Kitahara Toshiyuki , Tsuyama Hiroaki , Inoue Kenichirou , Ito Masaharu
Published: October 2013

We developed a new fabrication method for multilayer optical discs for the high-throughput production of such discs. We used web coating and lamination to prepare a stacked unit. The stacked unit was a layered structure consisting of a recording layer, a UV resin layer, a recording layer, and a pressure-sensitive adhesive layer. We obtained a 20-layer disc simply by laminating the stacked units 10 times. The transmittance of the 20 recording layers was 87% owing to the high transparency of the two-photon recording material. A scanning electron microscopy (SEM) image of the disc showed a clear multilayer structure. The recording layers of the disc were recorded using a pulse laser without interlayer cross write. The thickness variation of the transparent part of the disc was within ±2 µm, and the tilt angles of the disc satisfied the Blu-ray disc (BD) specifications.
Basic Physical Construction Method for Preformatted Information on the Guide Layer of Super-Multilayer Disc
Authors: Shiroto Takuya , Yoshida Masayoshi , Tagiri Takao , Nishiwaki Hiroshi , Ogasawara Masakazu , Taniguchi Shoji
Published: October 2013

In this paper, we describe a new physical construction method to assign preformatted information on the guide layer of a super-multilayer disc. A minimum unit of the physical construction consists of “basic mark” and “center track mark”. The basic mark consists of plural wobbled grooves and the center track mark is introduced to identify the center track of the basic mark. We designed a new physical format of the guide layer allocating those marks and experimentally confirmed the bit error rate below 1×10-4 and the defocus margin around 3 µm, which satisfy requirements for realizing an optical disc system.
Digital Image Diffusion Technique for Suppressing Interpage Crosstalk in Holographic Data Storage
Authors: Shibukawa Atsushi , Okamoto Atsushi , Wakayama Yuta , Tomita Akihisa , Funakoshi Hisatoshi , Sato Kunihiro
Published: October 2013

To suppress interpage crosstalk that strongly restricts holographic data storage capacity, a digital image diffusion technique was proposed. In this technique, signal and crosstalk components are separated from the propagation angle difference produced by using a random diffuser and the nature of phase conjugate lights. The most attractive feature of the technique is that crosstalk suppression can be conducted while mostly keeping the conventional holographic data storage system unchanged by integrating optical processing and digital processing effectively. The connection between the two types of processing is realized by using two spatial light modulators for complex amplitude generation and phase detection methods for complex amplitude measurement. The simulation results showed that the proposed technique could increase the recording density 5.5-fold and reduce the shift pitch by a factor of 5 in comparison with conventional multiplexing methods when the diffusion angle of the diffuser is 10°.
Method of Phase and Amplitude Modulation/Demodulation Using Datapages with Embedded Phase-Shift for Holographic Data Storage
Authors: Bunsen Masatoshi , Umetsu Shuhei , Takabayashi Masanori , Okamoto Atsushi
Published: October 2013

A technique for the phase and amplitude detection of object beams with multivalued phase and amplitude modulation is proposed for holographic storage systems. Generally, the spatial distribution of the complex amplitude of the object beam can be precisely detected by phase-shifting interferometric measurements in which the phase of the reference wave for interferometry is temporally or spatially changed in the datapage retrieval process. On the other hand, our technique allows fast, accurate, and feasible phase and amplitude demodulations by preliminary embedding phase shift into the phase signal of the datapage during recording. This technique will significantly improve the data transfer rate and vibration tolerance of the holographic storage system because the complex amplitudes of the object beam carrying datapages can be detected by single-shot image capturing. The optical system for datapage replay will also be simplified because there is no need to use any phase-shifting device during data retrieval. The single-shot detection of the phase-modulated datapage is experimentally demonstrated.
Real-Image Generation in Normal Viewing Disk-Type Multiplex Holography and Design of Replication Method
Authors: Cheng Yih-Shyang , Chen Chih-Hung
Published: October 2013

In this study, the fabrication method and the parameter design for real-image display in normal viewing image-plane disk-type multiplex holography are described. Concept of two-step holographic copying for this kind of hologram is theoretically and experimentally demonstrated. The quantitative analysis for image quality of finished hologram is also presented.
Simplified Transfer Function of Write Compensation for Phase-Change Optical Disks
Authors: Tanabe Takaya , Sakamoto Kotaro , Okubo Kohei
Published: October 2013

A simplified transfer function for write compensation is given by the inverse function of the cooling transfer function of a phase-change optical disk. The areas at a phase-change recording layer irradiated with an optical beam melt and change to marks. The marks are formed when the area is rapidly cooled; however, the marks disappear in a slowly cooled situation. Thus, the cooling process was considered essential for the mark formation on a phase-change optical disk. Therefore, the transfer function of the mark formation combined a heating component before mark formation with that after mark formation using a lag element. It was also found that the transfer function for write compensation could be achieved using a two-stage pulse train method. Experimental results showed that long marks were recorded by the pulse train method with the same frequency characteristic as our theoretical analysis.
Double Feedforward Control System Based on Precise Disturbance Modeling for Optical Disk
Authors: Sakimura Naohide , Nakazaki Tatsuya , Ohishi Kiyoshi , Miyazaki Toshimasa , Koide Daiichi , Tokumaru Haruki , Takano Yoshimichi
Published: October 2013

Optical disk drive systems must realize high-precision tracking control for their proper operation. For this purpose, we previously proposed a tracking control system that is composed of a high-gain servo controller (HGSC) and a feedforward controller with an equivalent-perfect tracking control (E-PTC) system. However, it is difficult to design the control parameter for actual multi-harmonic disturbances. In this paper, we propose a precise disturbance model of an actual optical disk using the experimental spectrum data of a feedback controller and describe the design of a fine tracking control system. In addition, we propose a double feedforward control (DFFC) system for further high-precision control. The proposed DFFC system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and trajectory command prediction. Our experimental results confirm that the proposed system effectively suppresses the tracking error at 6000 rpm, which is the disk rotation speed of Digital Versatile Disk Recordable (DVD+R).
Focusing Characteristics of a Spiral Plasmonic Lens
Authors: Takeda Minoru , Okuda Shinpei , Inoue Tsutomu , Aizawa Kento
Published: October 2013

A plasmonic lens (PL) is one of the promising photonic devices utilizing the surface plasmon wave. The surface plasmon wave can be focused using a PL structure consisting of only a single annular subwavelength slit milled into a metal film on a glass substrate. Recently, we have evaluated the beam focusing characteristics of a PL for 532 nm wavelength, which consists of a circular slit aperture of 4 µm diameter, using near-field scanning optical microscopy (NSOM), and confirmed that subwavelength focusing was attained at the center axis of the PL in both the near-field and far-field regions. However, for a PL with a circular slit, finite-difference time-domain (FDTD) simulations show that the focusing of the surface plasmon induced electric field into a single solid spot at the center cannot be achieved using circularly or linearly polarized light owing to the destructive interference between counter propagating surface plasmon waves from opposite circle slit points. In this study, we designed and fabricated a new PL with a spiral slit for 405 nm wavelength to produce a single solid focal spot due to the constructive interference at the nominal center of the PL. We measured the focusing characteristics of the PL and attained a tightly focused beam with a subwavelength spot size (∼330 nm) at 3.5 µm above the PL surface.
Efficiency Improvement of 630 nm AlGaInP Light-Emitting Diodes based on AlGaAs Bottom Window
Authors: Lee Hyung Joo , Kim Young Jin , Kim Seong Un , Jo Ju Ung , Lee Choong Hun , Kim Jae Hoon , Ahn Su Chang
Published: October 2013

Metal organic chemical vapor deposition (MOCVD) based aluminum gallium arsenide (AlGaAs) used as the bottom window (BW), which was inserted between the light-emitting diode (LED) structure and the absorbing substrate, has been proposed to improve the extraction efficiency of 630 nm AlGaInP LEDs. In an AlGaInP LED with this AlGaAs BW, enhanced light extraction efficiency was observed, as some of the light emitted from the active region to the absorbing substrate could pass out of the LED through the BW. In addition, it was found that a output power of 8 mW was obtained from an AlGaInP LED with both a BW and a distribution Bragg reflector (DBR), a nearly two fold improvement of over 4.2 mW that was obtained from a conventional one at an injection current of 80 mA.
Thermal and Optical Properties of InGaN/GaN Green Vertical Light-Emitting Diodes on Molybdenum Substrate for Different Submounts
Authors: Lee Soo Hyun , Kim Seung Hwan , Song Young Ho , Jeon Seong-Ran , Yu Jae Su
Published: October 2013

We reported the thermal and optical properties of InGaN/GaN multiple quantum wells green (λ∼525 nm) vertical light-emitting diodes (VLEDs) with a large chip size of 1 ×1 mm2 on molybdenum substrate. In the temperature range of 298–358 K, the temperature-dependent measurement of the packaged VLEDs on metal printed circuit board (MPCB) submount was performed, indicating a characteristic temperature of ∼456 K at 350 mA. At 298 K and 350 mA, the optical output power, operating voltage, and peak emission wavelength were measured to be 110.7 mW, 3.52 V, and 524.1 nm, respectively, and the view angle of Lambertian radiation pattern was about 120° at full width at half maximum. The forward voltage method was used to measure the junction temperature (T
j) of VLED devices. From the measured T
j values, the thermal resistance (R
th) value was experimentally obtained to be ∼14.62 K/W for VLEDs on the MPCB. In comparison, the R
th value of the devices on copper submount was decreased to ∼9.16 K/W.
Cu Doping of CdTe Layers in Polycrystalline CdTe Thin-Film Solar Cells for Top Cells of Multijunction Solar Cells
Authors: Okamoto Tamotsu , Hayashi Ryoji , Hara Shigeki , Ogawa Yohei
Published: October 2013

The Cu doping of CdTe layers in CdTe solar cells without using a Cu-doped carbon electrode was investigated in order to develop transparent back contacts for multijunction solar cells. Cell performance was drastically improved by heat treatment after coating with Cu-doped diethylene glycol monobutyl ether (DEGBE) as compared with the cell without Cu doping. Capacitance–voltage (C–V) characteristics revealed that the acceptor concentration increased with increasing Cu concentration in DEGBE. These results suggest that Cu atoms are incorporated into the CdTe layer as acceptors by the novel Cu-doping method. Furthermore, in photoluminescence (PL) spectra of CdTe layers, the intensity of the 1.47 eV emission band was decreased by the heat treatment after coating with Cu-doped DEGBE, which suggests that the defect density is decreased by Cu doping.
In situ X-ray Photoemission Spectroscopy Analysis of Aromatic Polyester Surface Treated with Argon Plasma
Authors: Narushima Kazuo , Okamoto Nanami
Published: October 2013

Effects of surface modification treatment by argon plasma processing of two types of aromatic polyester, poly(ethylene terephthalate) (PET) and poly(oxybenzonate-co-oxynaphthoate) (POCO), were investigated. This paper presents a description of our experiment and a discussion of the surface modification mechanism, which uses a simple and inexpensive procedure to conduct analysis without breaking vacuum after plasma processing. In situ analysis of the chemical composition of a polymer surface was attempted without exposing the sample to air after argon plasma processing. In particular, the respective actions of each active species were investigated for electrons and ions in argon plasma. Electrons and ions in argon plasma break some polymer bonds. Specifically, ester groups are broken and oxygen atoms are kicked out in PET and POCO. No oxygen functional group is formed after argon plasma processing, but such groups are formed if the sample is exposed to air.
Characterization of Porous Structures in Advanced Low-k Films with Thin TaN Layers Using Monoenergetic Positron Beams
Authors: Uedono Akira , Verdonck Patrick , Delabie Annelies , Swerts Johan , Witters Thomas , Conard Thierry , Baklanov Mikhail R. , Elshocht Sven Van , Oshima Nagayasu , Suzuki Ryoichi
Published: October 2013

Pore sizes and their depth distributions in advanced low-k (ALK) films fabricated using plasma-enhanced chemical vapor deposition were determined using monoenergetic positron beams. The measurement of the energy distributions of annihilation γ-rays and the positron lifetime spectra of the ALK films before and after thin TaN atomic layer deposition showed that Ta atoms diffused into the films. As a result, mean pore size decreased, with the number of larger pores decreasing preferentially. From the measurements of the electron momentum distribution, we found that almost all the inner walls of pores were covered by Ta for the ALK film without pretreatment before TaN deposition. The penetration of Ta into the film, however, was suppressed by plasma treatment using an Ar/N2 or Ar/H2 gas mixture, where the Ar/N2-plasma treatment more effectively blocked Ta diffusion than the Ar/H2-plasma treatment. Through this work, we have demonstrated that monoenergetic positron beams are a powerful tool for characterizing capped porous films and the trapping of metallic atoms by pores.
High-Throughput and Low-Cost Fabrication of Polymer Microscanner for Lighting Applications
Authors: Kurihara Kazuma , Nagumo Osamu , Takamatsu Seiichi , Takagi Hideki , Maeda Ryutaro
Published: October 2013

A high-throughput and low-cost fabrication process for an optical microscanner is proposed for lighting applications. The process utilizes mold replication and transfer of printed functional layers to form a film. We confirmed that a high-throughput fabrication lasting less than 30 s could be obtained by using a mold with a knife edge. A polymer microscanner with feature size of 0.6×2 mm2 was successfully fabricated using our process. The scanner was actuated by magnetic forces generated by an external coil, and the mirror tilt angle was successfully measured by a strain gauge formed by the functional layer transfer. By synchronizing the LED input signal and the polymer scanner tilt angle, the illuminance distribution could be controlled. For example, this distribution could be expanded from 10 to 50° or divided into two separated spots. We believe that our developed process can address new MEMS applications such as commercial lighting.
Improved Performance of (112̄2) Semipolar InGaN/GaN Light-Emitting Diodes Grown Using a Hemispherically Patterned SiO2 Mask
Authors: Min Daehong , Yoo Geunho , Ryu Yongwoo , Moon Seunghwan , Nam Kibum , Lim Hongchul , Nam Okhyun
Published: October 2013

In this paper, we report on the improved performance of (112̄2) semipolar InGaN/GaN light-emitting diodes (LEDs) grown using a hemispherically patterned SiO2 mask on an m-plane sapphire substrate (HP-SiO2), in comparison with a planar m-plane sapphire substrate and a hemispherically patterned m-plane sapphire substrate (HPSS), by metalorganic chemical vapor deposition. The full widths at half maximum of X-ray rocking curves for the on- and off-axes planes of the GaN layers on HP-SiO2 were the narrowest of the three samples. Cross-sectional transmission electron microscopy images showed larger low defect areas of GaN layers on HP-SiO2 than on HPSS. The electroluminescence results showed that the optical powers of LEDs on HPSS and HP-SiO2 increased by approximately 2.7 and 6 times, respectively, over that of m-planar sapphire at 100 mA. Our results suggest that the introduction of HP-SiO2 is very effective to improve the crystal quality as well as the light extraction efficiency of semipolar InGaN LEDs.
Investigation of Light Extraction Efficiency and Internal Quantum Efficiency in High-Power Vertical Blue Light-Emitting Diode with 3.3 W Output Power
Authors: Jeong Tak , Baek Jong-Hyeob , Jeong Ki Chang , Ha Jun-Seok , Ryu Han-Youl
Published: October 2013

Light extraction efficiency (LEE) and internal quantum efficiency (IQE) of InGaN-based vertical blue light-emitting diode (LED) structures are investigated by numerical simulations and experiments. LEE of vertical LEDs is calculated for various structural and material parameters by using three-dimensional finite-difference time-domain (FDTD) simulations, and the optimum textured patterns on the n-GaN surface is found from the FDTD simulation. High-power vertical LED structures are fabricated based on the simulation results. The output power at 3 A injection current is measured to be 3.3 W, and the peak value of the external quantum efficiency (EQE) is found to be 64%. In addition, LEE of the fabricated vertical LED is expected to be 70–80% from the FDTD simulations. Combining the results of EQE and LEE, the peak IQE of the experimented vertical LED can be estimated to be 80–90%.
Energy Harvesting Characteristics from Water Flow by Piezoelectric Energy Harvester Device Using Cr/Nb Doped Pb(Zr,Ti)O3Bimorph Cantilever
Authors: Kim Kyoung-Bum , Kim Chang Il , Jeong Young Hun , Cho Jeong-Ho , Paik Jong-Hoo , Nahm Sahn , Lim Jong Bong , Seong Tae-Hyeon
Published: October 2013

A water flow energy harvester, which can convert water flow energy to electric energy, was fabricated for its application to rivers. This harvester can generate power from the bending and releasing motion of piezoelectric bimorph cantilevers. A Pb(Zr0.54Ti0.46)O3+ 0.2 wt % Cr2O3+ 1.0 wt % Nb2O5(PZT–CN) thick film and a 250-µm-thick stainless steel were used as a bimorph cantilever. The electrical impedance matching was achieved across a resistive load of 1 kΩ. Four bimorph cantilevers can generate power from 5 to 105 rpm. The output powers were steadily increased by increasing the rpm. The maximum output power was 68 mW by 105 rpm. It was found that the water flow energy harvester can generate 58 mW by a flow velocity of (2 m/s) from the stream with the four bimorph cantilevers.
Directional Solidification Behaviors of Polycrystalline Silicon by Electron-Beam Melting
Authors: Lee Jun-Kyu , Lee Jin-Seok , Jang Bo-Yun , Kim Joon-Soo , Ahn Young-Soo , Cho Churl-Hee
Published: October 2013

The advanced electron beam melting (EBM) system with the combination of vacuum refining and directional solidification (DS) performed the purification of large amounts of metallurgical grade silicon (MG-Si). In order to increase grain size or to align columnar grains being parallel to DS pulling direction in Si ingots, non-irradiated inner diameters in an EB pattern in the DS process were varied at a range of 5–35 mm. Average grain size increased with increasing non-irradiated inner diameter due to a smaller temperature gradient during the solidification of Si melts. However, the slope of the grain boundary inclined towards the ingot axis, which led to the formation of a triple junction in the ingot center in the case of large non-irradiated inner diameter. This happened despite there being a large temperature gradient due to the turbulent flow in the pool. This work reported that a purity of 99.8% for MG-Si was improved to above 99.999% with an ingot yield of 90% for 1 h.
Metal Foam as Positive Electrode Current Collector for LiFePO4-Based Li-Ion Battery
Authors: Yang Gui Fu , Song Jae Sun , Kim Hyung Yoon , Joo Seung Ki
Published: October 2013

In order to improve the kinetic performance of LiFePO4-based Li-ion batteries, three dimensional metal foams were used as positive current collector. In the case of conventional Ni foam, the organic electrolyte of the cell was decomposed with the ionization of Ni during charge and discharge. The low tolerance of Ni was solved by using NiCrAl foam which was manufactured by alloying NiCrAl powder with Ni foam. From the electrochemical analysis, it shows that the kinetic performance of the cell by using a three dimensional NiCrAl foam was much superior to that in the case of conventional foil type.
Solid-State Synthesis and Thermoelectric Properties of Al-Doped MnSi1.75-δ
Authors: Shin Dong-Kil , You Sin-Wook , Kim Il-Ho
Published: October 2013

Al-doped higher manganese silicides (HMS), MnSi1.75-δ:Alxwere synthesized by solid state reaction and hot pressing. Through X-ray diffraction analysis of the synthesized HMS, the optimum conditions for solid state reaction were determined to be 1273 K for 6 h. Phase fractions of HMS with compositional variation (δ) had no significant difference, but the MnSi1.75:Al0.005specimen had the highest fraction of HMS at approximately 98.36%. All specimens showed p-type conduction at all temperatures examined, and exhibited degenerate semiconductor characteristics, in that the electrical conductivity decreased and the Seebeck coefficient increased with increasing temperature. Al doping shifted the onset temperature of intrinsic conduction to higher temperature. Thermoelectric figure of merit (ZT) of HMS increased with increasing temperature, and further improvement was achieved by Al doping. The maximumZTwas obtained as 0.41 at 823 K for MnSi1.73:Al0.005.
Formation of Graphene-on-Diamond Structure by Graphitization of Atomically Flat Diamond (111) Surface
Authors: Tokuda Norio , Fukui Makoto , Makino Toshiharu , Takeuchi Daisuke , Yamsaki Satoshi , Inokuma Takao
Published: October 2013

We succeeded in the formation of a graphene-on-diamond (GOD) structure by the graphitization of a diamond (111) surface. Before the graphitization, atomically flat diamond (111) surfaces were formed by homoepitaxial lateral growth. The graphene layers, which were formed on the atomically flat diamond (111) surfaces horizontally, were observed by cross-sectional high-resolution transmission electron microscopy.
Formation of Diamond-Like Carbon Films by Photoemission-Assisted Plasma-Enhanced Chemical Vapor Deposition
Authors: Yang Meng , Takabayashi Susumu , Ogawa Shuichi , Hayashi Hiroyuki , Ješko Radek , Otsuji Taiichi , Takakuwa Yuji
Published: October 2013

Diamond-like carbon (DLC) films, which are an amorphous carbonaceous allotrope composed of sp2carbon, sp3carbon, and hydrogen, were prepared by photoemission-assisted plasma-enhanced chemical vapor deposition (PA-PECVD). The electrical behavior during film growth monotonically depended on the methane source gas concentration. Raman analysis of the films suggests that a DLC film grown at a high methane concentration condition contains a small number of graphitic domains, decreasing amorphicity of the film. In contrast, at a low concentration, the methane molecules were transformed into sufficiently fragmented radicals, forming a lot of graphitic nuclei and increasing the amorphicity. However, the variations of the relative dielectric constant, breakdown strength, and optical bandgap exhibited extreme values at an intermediate methane concentration. Thus, the two growth modes give different DLC films with varying combinations of electrical and optical characteristics.
Formation of Eu3+ Luminescent Centers in Eu-Doped ZnO Grown by Sputtering-Assisted Metalorganic Chemical Vapor Deposition
Authors: Tsuji Takahiro , Terai Yoshikazu , Kamarudin Muhammad Hakim Bin , Fujiwara Yasufumi
Published: October 2013

The photoluminescence (PL) and electrical properties of Eu-doped ZnO (ZnO:Eu) grown by sputtering-assisted metalorganic chemical vapor deposition (SA-MOCVD) were investigated. Sharp PL lines due to intra-4f transition in Eu3+ ions were observed when ZnO:Eu was annealed at temperatures (T
a) higher than 500 °C in O2 ambient. In Hall measurements, the as-grown ZnO:Eu showed a high electron density of 3×1019 cm-3, indicating that the doped Eu ions act as a donor in ZnO. The electron density decreased rapidly at T
a≥500 °C and was 2×1017 cm-3 at T
a = 600 °C. These results revealed that a complex consisting of a Eu3+ ion and an interstitial oxygen (Eu3+–Oi complex) is formed by high-temperature annealing and acts as a Eu3+ luminescent center in ZnO.
Phase Recovery Acceleration of Quantum-Dot Semiconductor Optical Amplifiers by Optical Pumping to Quantum-Well Wetting Layer
Authors: Kim Jungho
Published: October 2013

We theoretically investigate the phase recovery acceleration of quantum-dot (QD) semiconductor optical amplifiers (SOAs) by means of the optical pump injection to the quantum-well (QW) wetting layer (WL). We compare the ultrafast gain and phase recovery responses of QD SOAs in either the electrical or the optical pumping scheme by numerically solving 1088 coupled rate equations. The ultrafast gain recovery responses on the order of sub-picosecond are nearly the same for the two pumping schemes. The ultrafast phase recovery is not significantly accelerated by increasing the electrical current density, but greatly improved by increasing the optical pumping power to the QW WL. Because the phase recovery time of QD SOAs with the optical pumping scheme can be reduced down to several picoseconds, the complete phase recovery can be achieved when consecutive pulse signals with a repetition rate of 100 GHz is injected.
Optoelectronic Properties of Indium–Tin Oxide Films Deposited on Flexible and Transparent Poly(dimethylsiloxane) Substrate
Authors: Lien Shui-Yang , Nautiyal Asheesh , Lee Shuo Jen
Published: October 2013

In this article, we report the thin-film deposition of indium–tin oxide (ITO) as a transparent conductive oxide (TCO) on a flexible and transparent poly(dimethylsiloxane) (PDMS) substrate by RF sputtering. PDMS, an elastomeric polymer, is highly transparent and can withstand much higher temperatures (∼200 °C) than other commercially used polymers in electronics. In this study, we discussed the Hall electrical measurements and optical transmittance data for ITO thin films on a PDMS substrate. We demonstrated that the transparent PDMS polymer is a new flexible TCO material, with suitable electrical and optical properties for use in electronic devices. An ITO thin film with an electrical resistivity of 3.8 ×10-5Ω cm, a carrier concentration of 5.9×1021cm3, a mobility of 3 cm2V-1s-1, and an average transmittance of 83% was achieved on the PDMS polymeric substrate.
Fluidic Self-Assembly Using Molten Ga Bumps and Its Application to Resonant Tunneling Diodes
Authors: Nakano Jun , Shibata Tomoaki , Morita Hiroki , Sakamoto Hiroshi , Mori Masayuki , Maezawa Koichi
Published: October 2013

Fluidic self-assembly (FSA) using molten metal bumps is one of the most promising heterogeneous integration (HI) technologies, which enable us to integrate devices made of various materials on various substrates. We can fabricate the metal bumps using Ga having diameters of 24, 18, 12, and 8 µm with good yield. Using Ga has significant advantages; especially, it includes no toxic metals. These bumps were used for the FSA process of the metal dummy blocks having a diameter of 18 µm, and a good yield of 84% was obtained all over the substrate of about 1×1 cm2. Finally, we applied this method to the resonant tunneling diode (RTD) to verify good electrical, mechanical, and thermal contacts. The RTD device blocks having a diameter of 24 µm have been successfully assembled using the molten Ga bumps. This method is promising for high-performance RTD integration.
Modeling an Inflammation‐Related Depressive Phenotype in Mice Using Bacille Calmette‐Guérin
Authors: Platt Brian J. , Clark Janet A.
Published: October 2013

The relationship between inflammation and neuropsychiatric symptoms is of interest to the scientific community for several reasons. A substantial subset of patients suffering from major depressive disorder also exhibit evidence of chronic inflammation including elevated levels of circulating pro‐inflammatory cytokines. Immune‐mediated inflammatory diseases and immunotherapy can result in depressive symptoms in some patients. Recent evidence suggests that the chronic inflammation may play a role in the pathophysiology of the depressive state, although the specific biological mechanisms are not clear. Herein we describe a model of an inflammation‐related depressive phenotype in mice using the tuberculosis vaccine, bacille Calmette‐Guérin, to induce chronic inflammation and a subsequent depressive phenotype which is assessed using the tail‐suspension test. The model provides an avenue to study not only the molecular and biochemical changes that may be associated with the development of the depressive phenotype, but also pharmacological manipulations of the phenotype. Curr. Protoc. Neurosci. 65:9.46.1‐9.46.10. © 2013 by John Wiley & Sons, Inc.
A recurrence‐based technique for detecting genuine extremes in instrumental temperature records
Authors: Faranda Davide , Vaienti Sandro
Published: October 2013

In this paper, we analyze several instrumental records of temperatures at different locations by using new techniques originally developed for the analysis of extreme values of dynamical systems. We show that they have the same recurrence time statistics as a chaotic dynamical system perturbed with dynamical noise and by instrument errors. The technique provides a criterion to discriminate whether the recurrence of a certain temperature belongs to the normal variability or can be considered as a genuine extreme event with respect to a specific timescale fixed as parameter. The method gives a self‐consistent estimation of the convergence of the statistics of recurrences toward the theoretical extreme value laws.
Nighttime vertical plasma drifts and the occurrence of sunrise undulation at the dip equator: A study using Jicamarca incoherent backscatter radar measurements
Authors: Ambili K. M. , Choudhary R. K. , St.‐Maurice J.‐P. , Chau Jorge L.
Published: October 2013

The absence of photoionization, in combination with sustained downward plasma motion at night, means that the F region can be severely depleted at the magnetic equator in the morning. As a result, at sunrise, there can be a sudden upward jump in altitude of the F region peak followed by a quick descent in association with the downward motion of the photoionization production peak. This constitutes what is known as the equatorial sunrise undulation. Its anecdotal existence has been reported over Jicamarca while it has been seen repeatedly over Trivandrum, India, during equinox conditions. By contrast, we find that the phenomenon is not as frequent at Jicamarca as at Trivandrum. Using incoherent backscatter radar data from Jicamarca, we show that the differences have an electrodynamical origin. The sunrise undulation gets masked when remnant plasma from the previous night does not move down to low enough altitude. The nighttime residual ion density and its altitude are found to be strongly influenced by the evening and nighttime electric field. There is a strong association between a strong plasma uplift at sunset and the appearance of an undulation at sunrise around the magnetic equator.