bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioural characteristics associated with dog bites to children presenting to an urban trauma centre
Authors: Reisner Ilana R , Nance Michael L , Zeller Jason S , Houseknecht Eileen M , Kassam-Adams Nancy , Wiebe Douglas J
Published: March 2011

Children are the most frequent victims of dog bites presenting to hospital emergency departments (ED), but there are gaps in understanding of the circumstances of such bites. The objective of this study was to characterise the behavioural circumstances of dog bites by interviewing children ≤17 years (or parent proxies for children ≤6 years) presenting with dog bite injuries to The Children's Hospital of Philadelphia about the bite incident, its setting and associated interactions. Of 203 children enrolled, 51% were <7 years old and 55% were male. 72% of children knew the biting dog. Most bites to younger children occurred during positive interactions, initiated by the child, with stationary, familiar dogs, indoors. Most older bitten children had been active (eg, outdoors), unfamiliar with the dog and not interacting. Whereas face bites predominated (70%) in the younger group (<7 years), bites to extremities predominated (72%) in the older group. Recognition of the two distinctive behavioural and circumstantial subgroups of dog bites that emerged can lead to more effective prevention strategies.
Effects of feeding management and time of day on the occurrence of self‐suckling in dairy goats
Authors: Martínez‐de la Puente J. , Moreno‐Indias I. , Morales‐Delanuez A. , Ruiz‐Díaz M. D. , Hernández‐Castellano L. E. , Castro N. , Argüello A.
Published: March 2011

The occurrence of self‐suckling was recorded in 21 dairy goats during periods of 20 minutes at three different times per day (immediately after milking and the first feed, immediately after the second feed and in the afternoon) for 27 days (divided into three experimental periods of nine days). As expected, negative associations between milk yield and the frequency of self‐suckling were observed (P<0.05). Goats suckled on their own right teat more frequently than on the left teat. The width of the right teat (measured at the middle of the teat) was positively associated with the frequency of self‐suckling after controlling for the width of the left teat. A higher self‐suckling frequency was observed immediately after milking than in the other two periods of the day. The frequency of self‐suckling by each goat was reduced when animals were supplemented ad libitum with wheat straw in addition to their ordinary feed.
Present Status and Future Prospects of Silicon Thin-Film Solar Cells
Authors: Konagai Makoto
Published: March 2011

In this report, an overview of the recent status of photovoltaic (PV) power generation is first presented from the viewpoint of reducing CO2 emission. Next, the Japanese roadmap for the research and development (R&D) of PV power generation and the progress in the development of various solar cells are explained. In addition, the present status and future prospects of amorphous silicon (a-Si) thin-film solar cells, which are expected to enter the stage of full-scale practical application in the near future, are described. For a-Si single-junction solar cells, the conversion efficiency of their large-area modules has now reached 6–8%, and their practical application to megawatt solar systems has started. Meanwhile, the focus of R&D has been shifting to a-Si and microcrystalline silicon (µc-Si) tandem solar cells. Thus far, a-Si/µc-Si tandem solar cell modules with conversion efficiency exceeding 13% have been reported. In addition, triple-junction solar cells, whose target year for practical application is 2025 or later, are introduced, as well as innovative thin-film full-spectrum solar cells, whose target year of realization is 2050.
Electrical Characterization of GaN p–n Junctions Grown on Freestanding GaN Substrates by Metal–Organic Chemical Vapor Deposition
Authors: Uesugi Tsutomu , Kachi Tetsu
Published: March 2011

The electrical characteristics of GaN p–n junctions grown on freestanding GaN substrates by metal–organic chemical vapor deposition were investigated. The current–voltage (I–V) characteristics of the GaN p–n diode showed relatively low values and, little temperature dependence of the reverse leakage current. The breakdown voltage of the GaN p–n diode was 900 V and the leakage current at 600 V was 1 µA/cm2 or less. The inverse of squared capacitance–voltage (1/C
2–V) data showed a linear relationship, indicating an abrupt junction at the p–n interface. Little temperature dependence of the C–V curve was also observed. Plasma etching before the growth of the p-GaN layer induced a large leakage current and a lower breakdown voltage, probably due to the disorder of atomic bonds and the nitrogen depletion at the plasma-etched surface. The insertion of a regrown n-GaN layer between the p-GaN and the plasma-treated n-GaN surface was effective in suppressing the leakage current and recovering the breakdown voltage.
Zn2LiGaO4, Wurtzite-Derived Wide Band Gap Oxide
Authors: Omata Takahisa , Kita Masao , Nose Katsuhiro , Tachibana Kosuke , Otsuka-Yao-Matsuo Shinya
Published: March 2011

The phase that appeared in the pseudo-binary LiGaO2–ZnO system was investigated by powder X-ray diffraction (XRD), selected area electron diffraction by transmission electron microscopy (TEM-SAD) and Raman spectroscopy, especially focusing on the 0.5(LiGaO2)1/2·0.5ZnO composition. A new quaternary wurtzite-derived Zn2LiGaO4 phase was found in this system. The TEM-SAD indicated that the phase possesses an incommensurately modulated ordering. The optical energy band gap of Zn2LiGaO4 was determined to be ∼4.0 eV from its diffuse reflectance and photoluminescence spectra; and it was suggested that the Zn2LiGaO4 was a direct semiconductor.
Photopumped Lasing Characteristics in Green-to-Yellow Range for BeZnSeTe II–VI Compound Quaternary Double Heterostructures Grown on InP Substrates
Authors: Nomura Ichirou , Sawafuji Yutaka , Kishino Katsumi
Published: March 2011

The photopumped lasing characteristics of double heterostructures with a BeZnSeTe active layer grown on InP substrates were systematically investigated. Green-to-yellow lasing emissions from 538 to 570 nm were observed at room temperature (RT). The threshold excitation power density (P
th) was approximately 30 kW/cm2. From the temperature dependence of P
th, stable lasing emissions were obtained up to 353 K. The characteristic temperatures of P
th were 106 to 140 K above RT. The relationship between the threshold gain (G
th) and the threshold carrier density (N
th) was estimated from the cavity length dependence of P
th and by waveguide analysis. Using the relationship between G
th and N
th, the threshold current densities (J
th) of electrically pumped BeZnSeTe laser diode structures were calculated to be less than 1.3 kA/cm2. J
th decreases as the lasing wavelength increases from 538 to 570 nm. The above results demonstrate that BeZnSeTe is a promising active-layer material for high-performance green-to-yellow LDs.
Effect of Annealing-Induced Interdiffusion on the Electronic Structure of Mid Infrared Emitting GaInAsSb/AlGaInAsSb Quantum Wells
Authors: Ryczko Krzysztof , Sęk Grzegorz , Motyka Marcin , Janiak Filip , Kubisa Maciej , Misiewicz Jan , Belahsene Sofiane , Boissier Guilhem , Rouillard Yves
Published: March 2011

There has been investigated the effect of post-growth-annealing-induced interdiffusion process, and hence interface intermixing, on the electronic structure of Ga0.35In0.65As0.32Sb0.68/Al0.25Ga0.50In0.25As0.24Sb0.76 single quantum well designed to emit light in the range of about 3 µm. The band structure and optical transitions have been calculated based on the single band effective mass model and Fick's interdiffusion law. The calculation results are consistent with the experimentally observed transitions obtained by employing modulation spectroscopy. Our studies indicate that the intermixing processes in this kind of quantum wells are predominantly induced by the interdiffusion of group III atoms. The derived effective diffusion coefficient has been estimated to be of the order of 10-21 m2 s-1 for 480 °C annealing temperature.
Seebeck Effects and Electronic Thermal Conductivity of IV–VI Materials
Authors: Ishida Akihiro , Yamada Tomohiro , Nakano Takayuki , Takano Yasushi , Takaoka Sadao
Published: March 2011

Theoretical calculations of the Seebeck coefficient and electronic thermal conductivity of general materials such as metals, semiconductors, and quantum structures are described, and the dependence of the Seebeck coefficient on doping level and temperature is discussed for lead-salt materials. Experimental Seebeck coefficient was measured for PbS films and the value agreed well with the theoretical value, indicating a high thermoelectric performance comparable to that of PbTe. The temperature dependence of electronic thermal conductivity is also discussed for lead salts. It is shown that minority carriers in the narrow-gap semiconductor significantly affect electronic thermal conductivity, and electronic thermal conductivity at high temperatures can be reduced by high-level doping.
Effect of Oxygen Vacancy and Oxygen Vacancy Migration on Dielectric Response of BaTiO3-Based Ceramics
Authors: Choi Youn-Kyu , Hoshina Takuya , Takeda Hiroaki , Tsurumi Takaaki
Published: March 2011

The effects of oxygen vacancies and their migrations on the dielectric responses of pure BaTiO3 (BT) ceramics and (Ba0.9Ca0.1)1.01(Ti0.9Zr0.1)O3 (BCTZ) ceramics, where portions of Ba and Ti were respectively substituted with Ca and Zr, were studied using wideband dielectric spectroscopy. The decrease in the dipole polarization of BT ceramics after annealing in a reducing atmosphere was due to domain-wall clamping by oxygen vacancies, while that of ionic polarization was attributable to lattice hardening by the incorporation of oxygen vacancies into the BT lattices. The dipole polarization of BCTZ ceramics indicated the same change as did that of BT ceramics after annealing, but the ionic polarization was independent of PO2 in annealing because of the anti-reducing behavior of BCTZ ceramics. The oxygen vacancy migration in BCTZ ceramics could be detected as a change of wideband dielectric spectra. The change observed only in the dipole polarization could be explained the oxygen vacancy migration from the anode to the cathode.
Enhanced Piezoelectric Constant of (1-x)BiFeO3–xBiCoO3 Thin Films Grown on LaAlO3 Substrate
Authors: Nakamura Yoshitaka , Kawai Masanori , Azuma Masaki , Kubota Makoto , Shimada Mikio , Aiba Toshiaki , Shimakawa Yuichi
Published: March 2011

Thin films of a rhombohedral-tetragonal solid solution (1-x)BiFeO3–xBiCoO3 with x = 0–0.30 were prepared by chemical solution deposition on LaAlO3(001) and (La0.5,Sr0.5)CoO3(001)/LaAlO3(001) substrates. A BiCoO3-type tetragonal structure with a large c/a of 1.23 was grown adjacent to the substrate whereas a BiFeO3-type rhombohedral one was grown on the tetragonal phase. Co substitution in the rhombohedral phase led to enhancement of piezoelectric constant and d
33 reached 100 pm/V, almost double that of BiFeO3.
Properties of Charge Carrier Transport in Au/Phenyl C61 Butyric Acid Methyl Ester/Au Structure
Authors: Sun Yong , Onwona-Agyeman Boateng , Miyasato Tatsuro
Published: March 2011

The properties of charge carrier transport through the Au/phenyl C61 butyric acid methyl ester/Au (Au/PCBM/Au) structure are studied by measuring DC currents passing through the structure at various temperatures and in the presence of an external electric field. Temperature- and field-strength dependent conductivities show that the energy band gap of the PCBM crystalline solid is 1.70 eV, and this value depends on the pressure during its preparation. There is a thermally activated process that controls the carrier mobility of this PCBM solid. We found out that its activation energy is influenced by the external electric field, and it increases with increasing field strength. The activation energy increases from 2 to 110 meV corresponding to a variation of the field strength from 50 to 1000 V cm-1. Theoretical calculation shows that the magnitude of the potential barrier for carrier transport through the structure increases only from 2 to 7 meV in the same field strength range owing to the Schottky effect on the Au/PCBM interface. Therefore, the field-strength-dependent mobility plays a more important role than the Schottky effect on the carrier transport through the structure.
Short Photonic-Crystal Directional Coupling Optical Switch of Extended Optical Bandwidth Using Flat Dispersion
Authors: Sugisaka Jun-ichiro , Yamamoto Noritsugu , Okano Makoto , Komori Kazuhiro , Itoh Masahide
Published: March 2011

A directional coupling optical switch is constructed from a photonic crystal having a wide optical bandwidth. It has flat dispersion, which allows considerable shortening of its length. The switching operation of a directional coupler having flat dispersion and of an ordinary directional coupler are compared, to prove that the device length can be as short as 4.68 µm (50 times shorter than the conventional one), while maintaining the input energy and bandwidth. A 1.17 µm optical switch is fabricated, simultaneously shortening the device and extending the optical bandwidth.
A Novel Birefringent Photonic Crystal Fiber and Its Application to Curvature Measurement
Authors: Hwang Kyu Jin , Kim Gil Hwan , Lim Sun Do , Lee Kwanil , Park Jin Woo , Lee Sang Bae
Published: March 2011

We demonstrate a curvature sensor with a newly designed photonic crystal fiber of high birefringence (Hi-Bi PCF). The proposed PCF has two large air holes in the outer cladding region that give rise to core ellipticity during the fabrication process. The curvature sensor is based on the PCF Sagnac interferometer, the output spectrum shift of which provides information on the PCF curvature. It turns out that the curvature sensitivity depends on the bending directions with respect to the large-air-hole alignment. For the two orthogonal bending directions, the curvature sensitivities near 1480 nm are -1.87 nm/m-1 (parallel to the axis of the two large air holes) and 1.24 nm/m-1 (perpendicular to the axis of the two large air holes), respectively, and are also insensitive to environmental temperature variation. The proposed curvature sensor may be useful in thin structural deflection measurement.
InGaAs/InAlAs Five-Layer Asymmetric Coupled Quantum Well Exhibiting Giant Electrorefractive Index Change
Authors: Arakawa Taro , Toya Takahiro , Ushigome Motoki , Yamaguchi Koichiro , Ide Tomoyoshi , Tada Kunio
Published: March 2011

An InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) exhibiting a giant electrorefractive index change was proposed and has been studied theoretically and experimentally. Giant electrorefractive sensitivity |d
n/d
F| (4.4×10-4 cm/kV) at a wavelength range with a width of over 100 nm can be expected at an electric field of approximately F=-30 to -60 kV/cm. The FACQW structure was successfully fabricated using molecular beam epitaxy (MBE). The results of photoabsorption current measurements are consistent with the theory. The giant electrorefractive index change of the FACQW is very promising for realizing low-voltage and high-speed compact Mach–Zehnder modulators and switches.
A Cadmium-Free Cu2ZnSnS4/ZnO Hetrojunction Solar Cell Prepared by Practicable Processes
Authors: Htay Myo Than , Hashimoto Yoshio , Momose Noritaka , Sasaki Kouichi , Ishiguchi Hiroshi , Igarashi Shigeo , Sakurai Kazuki , Ito Kentaro
Published: March 2011

A cadmium-free Cu2ZnSnS4/ZnO hetrojunction solar cell with conversion efficiency of 4.29% has been obtained. The Cu2ZnSnS4 absorber film was formed utilizing sulfurization of laminated metallic precursors, and the ZnO buffer layer was then deposited on it by ultrasonic spray pyrolysis. In comparison with a conventional Cu2ZnSnS4/CdS hetrojunction solar cell, the open circuit voltage as well as the relative quantum efficiency at the short-wavelength regions was increased. The in-plane homogeneity of p–n junction was improved by depositing the ZnO layer on Cu2ZnSnS4 film via ultrasonic spray pyrolysis.
Vector Gratings Fabricated by Polarizer Rotation Exposure to Hydrogen-Bonded Liquid Crystalline Polymers
Authors: Emoto Akira , Wada Takumi , Shioda Tatsutoshi , Sasaki Tomoyuki , Manabe Sayaka , Kawatsuki Nobuhiro , Ono Hiroshi
Published: March 2011

We present a simple yet efficient, competitive, and practical fabrication method, called “polarizer rotation exposure”, for preparing vector gratings with a large area and a high diffraction efficiency. The polarization states of ultraviolet light were modulated by rotating the polarizer, and the resultant ultraviolet light was line-focused onto hydrogen-bonded liquid crystalline polymer films set on a linear stage. Mesogenic molecules in the polymer films were reoriented according to the light electric vectors, and vector gratings in which the optical anisotropy is periodically modulated were fabricated by the polarizer rotation exposure method.
Non-degenerated Four-Wave Mixing Generated Power Ratio between Co-Propagated Pump Fabry–Perot Modes and Probe Signal in a Non-zero Dispersion Shifted Fiber
Authors: Kung Tsu-Te , Chen Chi-Feng
Published: March 2011

We theoretically and experimentally study of the four-wave mixing (FWM) that exists between the co-propagated pump Fabry–Perot (FP) modes of a FP laser diode (FPLD) and the single wavelength probe signal in a 25 km of non-zero dispersion shifted fiber (NZDSF) with zero dispersion wavelength of 1495 nm. The 100-mW co-propagated FP spectra centered at 1440 nm are reproduced via FWM around the 1-mW single wavelength signal around 1552 nm. The maximum FWM generated power ratio is found to have the first condition in matching of the group indices of the pump and signal to obtain the maximum FWM efficiency. And the second condition is mapping the signal wavelength to the center wavelength of the FP pump modes to have the adjacent FP modes with larger powers. The zero-dispersion wavelength of NZDSF can also be determined at the middle of the signal and the center wavelength of pump to have the maximum FWM generated power ratio.
Three-Dimensional Optical Measurement with Spectroscopic Function Using Fiber Laser Supercontinuum
Authors: Ohta Takefumi , Nishizawa Norihiko , Ozawa Tetsuya , Itoh Kazuyoshi
Published: March 2011

A three-dimensional (3D) measurement system with spectroscopic function was demonstrated using a practical supercontinuum light source and an all-fiber interferometer. Spectral information was obtained by Fourier transformation of the observed interference signal. We obtained the absorbances of various plastics. In addition, the system was capable of discerning different surface asperities that were smaller than the spatial resolution of the system by observing the spectral modulation caused by spectral interference that occurred when there was an asperity in the irradiated beam spot. The frequency of the spectral modulation depended on the height of the asperity. In this paper, the spectral modulation was analyzed by numerical calculations, and images based on the spectral modulation differences were obtained experimentally. The longitudinal and transverse resolutions were 3.0 and 125 µm, respectively. Based on the spectral modulation, we demonstrated that our 3D measurement system could obtain images of asperities of diameters 3, 6, 15, and 90 µm, which were smaller than the spatial resolution. A clear 3D image of a metallic cylinder with a small blemish was also obtained using this system.
Compensation of Incomplete Round Trip in an Herriott Multipass-Based Kerr-Lens Mode-Locked Ti:Sapphire Oscillator via an Output Coupler Position
Authors: Song Dong Hoon , Hwang Sung In , Ko Do-Kyeong
Published: March 2011

We examined the soft-aperture Kerr-lens mode-locked femtosecond Ti:sapphire oscillator derived from an Herriott multi-pass cavity (HMPC). Additionally, a novel and simple configuration was provided to extend the cavity length, the HMPC consisting of notched, flat and curved (R = 4 m) mirrors by which beams were injected and extracted. To compensate for beams which failed to complete round trips, the configuration was designed and analyzed as a function of the output coupler position. Such an oscillator generated 21.5 nJ, 34 fs pulses at a repetition rate of approximately 13.5 MHz; the spectral bandwidth represented 20 nm, corresponding to a time-bandwidth product of 0.33, assuming a sech2 fit.
Study of Noise in Current-Perpendicular-to-Plane Giant Magnetoresistance Devices with a Current Screen Layer
Authors: Nakao Ryota , Shiiki Kazuo
Published: March 2011

The noise in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices with a current screen layer (CSL) is investigated to clarify the noise generation mechanism. The noise intensity is greatly enhanced in the antiparallel magnetization configuration due to spin torque effects. In addition, the noise intensity increases as the temperature is reduced because thermal spin fluctuations decrease. Furthermore, the noise intensity increases when spins flow to the free layer because the magnetization of the free layer fluctuates easily. These results imply that noise is generated by fluctuations in the magnetization of the free layer caused by spin torque. Moreover, some CPP-GMR devices with a CSL have some peaks in plots of noise intensity against applied magnetic field. These peaks are thought to be related to the current-induced field and magnetization fluctuations at the edge of the device.
Stability Diagrams of Triple-Dot Single-Electron Device with Single Common Gate
Authors: Imai Shigeru
Published: March 2011

Triple-dot single-electron devices with a single common gate have been studied. The overall stability diagram of the single-electron device with a homogeneous tunnel capacitance C
j and a homogeneous gate capacitance C
g is derived algebraically. If the set of excess electron numbers in the three islands (n
1, n
2, n
3) is (n, n, n), (n, n + 1, n), or (n, n - 1, n), where n is an arbitrary integer, the corresponding stability region S(n
1, n
2, n
3) exists for any C
g/C
j. S(n, n, n), S(n, n + 1, n), and S(n, n - 1, n) for all n are arranged along the V
g axis in the order of n
1 + n
2 + n
3, where V
g is gate voltage, and neighboring stability regions overlap for any C
g/C
j ratio. Overlaps between S(n, n, n) and S(n, n ±1, n) for all n have identical kite-like shapes. Overlaps between S(n, n + 1, n) and S(n + 1, n, n + 1) for all n have identical rhombus shapes. Turnstile operations are possible by alternating gate voltage around overlaps between S(n, n, n) and S(n, n ±1, n) and around overlaps between S(n, n + 1, n) and S(n + 1, n, n + 1), though the sequences of single-electron transfers are different. The range of drain voltage and the swing of gate voltage for turnstile operation are estimated. The overlap between S(n, n + 1, n) and S(n + 1, n, n + 1) seems superior to the overlap between S(n, n, n) and S(n, n ±1, n) because of the larger ratio of the drain voltage range to the gate voltage swing, though the overlap between S(n, n + 1, n) and S(n + 1, n, n + 1) might require higher reliability against the nonuniformity of gate capacitances.
Self-Ordered Nanopore Arrays with 300–400 nm Interpore Distances Formed by High Field Accelerated Mild Anodization
Authors: Ramazani Abdolali , Kashi Mohammad Almasi , Maleki Keyvan , Mohammadniaei Mohsen
Published: March 2011

High field accelerated mild anodization was used to fabricate self-ordered nanoporous alumina arrays. The phosphoric acid with various concentrations was used in a wide range of anodization voltages. Two different temperatures for both sides of the samples were employed to maintain a mid level of current density during the anodization process. The interpore distances were seen to vary from 300 to 400 nm when the anodization voltages changed from 150 to 190 V. A nonlinear-inverse relation between electrolyte concentrations of phosphoric acid and anodization voltages was found in the optimum self-ordering conditions. Similar to the hard anodization, the ratio of interpore distance to voltage was 2 nm/V in high field accelerated mild anodization technique.
Fabrication of Nanogap Electrodes by the Molecular Lithography Technique
Authors: Nishino Takayuki , Negishi Ryota , Tanaka Hirofumi , Ogawa Takuji , Ishibashi Koji
Published: March 2011

We have developed fabrication processes of nanogap electrodes with various metals, by combining the molecular lithography technique, in which self-assembled molecular (SAM) layers with an accurately defined thickness are used for resist, and the electron beam lithography. Until now, the molecular lithography technique has been applied to Au and Pt to fabricate the nanogap electrodes, because a thiol-group of the termini molecule that the SAM resist contains is easily stuck to these metals. In this work, we have extended the technique to various metals on which the SAM layers is hard to be formed, with the help of the X-ray photoelectron spectroscopy (XPS) to obtain information on adhesion conditions of the SAM layers on the metals. Finally, we demonstrate fabrication of the Nb nanogap electrodes with the developed technique. An Au nanoparticle was embedded in between the nanogap, which showed the Coulomb blockade effect and the superconducting gap in the current–voltage curves.
Numerical Investigation of the Growth Rate Enhancement of SiC Crystal Growth from Silicon Melts
Authors: Mercier Frédéric , Nishizawa Shin-ichi
Published: March 2011

Numerical study has been applied to analyze the high temperature solution growth process for bulk silicon carbide (SiC) crystal growth. A two-dimensional axisymmetric model for 2-in. SiC crystal growth was used for this study. The purpose of this paper is to investigate the possible approaches to enhance the growth rate in this process. In particular, we studied the effect of an AC magnetic field on the carbon transport to the crystal growth interface. The results revealed that the carbon flux to the growing crystal is strongly affected by the coil position and the applied frequency. If these two process parameters are properly chosen, we show that the carbon flux at the growing front, and thus the growth rate of SiC, can be enhanced.
Diamond-like Carbon Films Deposited at Room Temperature on Flexible Plastics Substrates for Antireflection Coating
Authors: Lin Chii-Ruey , Wei Da-Hua , Chang Chien-Kuo , Liao Wen-Hsiang , Peng Kang Ran
Published: March 2011

In this present work, diamond-like carbon (DLC) films were coated onto polycarbonate (PC) substrates as a protective layer at room temperature by radio frequency (rf) magnetron sputtering technique. TheID/IGratio, roughness (Ra), and contact angle of amorphous DLC films could be controlled by regulating deposition power. The DLC films deposited at 150 W with a good hardness of as high as 13.74 GPa were realized with a surface roughness and contact angle of 0.63 nm (Ra) and 103°, respectively. Ultraviolet/visible (UV/vis) spectrophotometry of single-layer DLC films showed a high transmissive ability (>80%) in the visible wavelengths. No cracks occurred on the surface of DLC films after the flexibility test 500 times at a frequency of 8.6 min-1. This confirms the excellent adhesion of DLC films on PC plastic substrates with potential applications in flexible optoelectronic devices.
Modification of Semianalytical Finite Element Model for Radio Frequency Sheaths in Single- and Dual-Frequency Capacitively Coupled Plasmas: II. Effects of Nonuniform Bulk Plasma Density and Charging at Dielectric Surface
Authors: Denpoh Kazuki , Shirafuji Tatsuru
Published: March 2011

The effects of nonuniform bulk plasma density and charging at dielectric surfaces have been incorporated into our multidimensional, semianalytical rf sheath model for single- and dual-frequency capacitively coupled plasmas based on the finite element method. The present modification allows us more accurate prediction of spatiotemporal distributions of potential and electric field in the sheath, and hence of electron and ion densities. The spatial distributions of the electric field and the potential above a junction of two different metals and those above a metal–dielectric interface obtained using the modified rf sheath model agree very well with measured data referred to in this study. This result proves the validity of our rf sheath model modified in this study.
Design of Large-Area Surface Wave Plasma Excited by Slotted Waveguide Antennas with Novel Power Divider
Authors: Ishijima Tatsuo , Toyoda Hirotaka , Takanishi Yudai , Sugai Hideo
Published: March 2011

Microwave discharge enables the production of high-density (≥1017m-3) large-area (≥5 m2) flat plasma, owing to its efficient absorption of surface waves. To irradiate microwaves over an entire plasma surface uniformly, an array of slotted waveguide antennas combined with a novel compact power divider is developed. A general guideline for designing the slot antenna array for desired plasma dimensions is presented. Furthermore, in accordance with the antenna design optimized by finite difference time domain (FDTD) simulation, a 915 MHz microwave plasma of 1.3 ×1.1 m2area was successfully produced, verifying the plasma uniformity with two-dimensional Langmuir probe measurements.
Lamb-Dip Laser-Induced Fluorescence Spectroscopy for Measuring Magnetic Field in a Plasma
Authors: Ogiwara Kohei , Aramaki Mitsutoshi , Yoshimura Shinji , Itoh Yuta , Kato Yoshiyuki , Tanaka Masayoshi Y.
Published: March 2011

We have developed a Lamb-dip laser-induced fluorescence (LIF) system to precisely measure the local magnetic field strength in a plasma. Utilizing the hole burning effect, we made sharp dips on the LIF spectrum as the frequency markers and accurately determined the Zeeman splitting by reading the frequency interval of the dips. The method is valid even in the conditions where the Doppler broadening of the LIF spectrum is larger than the Zeeman shift. The newly developed LIF system is capable of determining a magnetic field strength on the order of 10-4T. It has been demonstrated that the Lamb-dip LIF system can successfully reproduce a very small field inhomogeneity in the HYPER-I linear device.
High-Rate Deposition of Amorphous Silicon Films by Microwave-Excited High-Density Plasma
Authors: Inoue Hirotada , Tanaka Kouji , Sano Yuichi , Nishimura Takehiro , Teramoto Akinobu , Hirayama Masaki , Ohmi Tadahiro
Published: March 2011

In this study, the deposition of amorphous silicon (a-Si) thin films using a microwave-excited high-density plasma system is described. We investigate the effects of plasma excitation gas species (argon or helium), total gas pressure, silane (SiH4) flow rate, and substrate stage temperature, estimating the resultant films from cross-sectional morphology, photoconductivity, and dark conductivity measured without light-induced degradation. It is confirmed that high-quality a-Si films (photosensitivity= 1.29 ×106) can be formed in the plasma excitation gas helium at a pressure of 13.3 Pa by relatively high rate (1.1 nm/s) deposition. At the same time, we measure the plasma emission derived from various radicals such as Si and SiH radicals in order to discuss the mechanism of radical generation in the plasma. The result of the measurement implies that when argon is used as plasma excitation gas, metastable states of argon markedly dissociate silane, which produces low-quality a-Si films. On the other hand, it seems that electrons dissociate silane mainly, which produces high-quality a-Si films, in helium.
Improved Retention Characteristic in Polycrystalline Silicon–Oxide–Hafnium Oxide–Oxide–Silicon-Type Nonvolatile Memory with Robust Tunnel Oxynitride
Authors: Hsieh Chih Ren , Lai Chiung Hui , Lin Bo Chun , Zheng Yuan Kai , Lou Jen Chung , Lin Gray
Published: March 2011

In this paper, we present a simple novel process for forming a robust and reliable oxynitride dielectric with a high nitrogen content. It is highly suitable for n-channel metal–oxide–semiconductor field-effect transistor (nMOSFETs) and polycrystalline silicon–oxide–hafnium oxide–oxide–silicon (SOHOS)-type memory applications. The proposed approach is realized by using chemical oxide with ammonia (NH3) nitridation followed by reoxidation with oxygen (O2). The novel oxynitride process is not only compatible with the standard complementary metal–oxide–semiconductor (CMOS) process, but also can ensure the improvement of flash memory with low-cost manufacturing. The characteristics of nMOSFETs and SOHOS-type nonvolatile memories (NVMs) with a robust oxynitride as a gate oxide or tunnel oxide are studied to demonstrate their advantages such as the retardation of the stress-induced trap generation during constant-voltage stress (CVS), the program/erase behaviors, cycling endurance, and data retention. The results indicate that the proposed robust oxynitride is suitable for future nonvolatile flash memory technology application.
Relationship of Electron Diffusion Length to Line Edge Roughness in Chemically Amplified Extreme Ultraviolet Resists
Authors: Kozawa Takahiro , Tagawa Seiichi
Published: March 2011

In chemically amplified resists, secondary electrons sensitize acid generators upon exposure to extreme ultraviolet (EUV) radiation. The migration of secondary electrons degrades the original EUV aerial image and increases the line edge roughness (LER). However, the longer the migration of secondary electrons is, the more acid generators are decomposed. Namely, the resist sensitivity increases with the migration of secondary electrons. Furthermore, the relationship of LER to the sensitivity is a trade-off one. Therefore, the relationship of the migration of secondary electrons to LER is complex. In this study, the effect of the migration of secondary electrons on the image quality was defined using the electron diffusion length specified to line-and-space patterns. The dependence of electron diffusion length and quantum efficiency on material properties was calculated on the basis of the sensitization mechanisms of chemically amplified EUV resists to investigate the relationship of the migration of secondary electrons to LER. Among material properties, the effect of thermalization distance on LER becomes significant below the 22 nm node. The reduction in thermalization distance leads to the reductions in both electron diffusion length and quantum efficiency. Although the reduction in thermalization distance is required to suppress electron diffusion length, the short thermalization distance does not necessarily lead to a low LER. It was found that the thermalization distance of ∼4 nm is sufficient in the resist design for the 16 nm node.
Development of a Surface Magneto-Transport Measurement System with Multi-Probes and the In situ Measurement of Bi Nanofilms Prepared on Si(111)7×7
Authors: Miyata Nobuhiro , Hobara Rei , Narita Hisashi , Hirahara Toru , Hasegawa Shuji , Matsuda Iwao
Published: March 2011

We have developed an independently-driven double probe-stage system that enables in situ magneto-transport measurements on surfaces and ultrathin films, prepared in ultrahigh vacuum. The measurements can be made at temperature down to 7.6 K and under magnetic field up to 7 T. The demonstration of Bi(001) crystal nanofilms on the Si(111)7×7 surface is presented.
Enhanced Contrast of Wavelength-Selective Mid-Infrared Detectors Stable against Incident Angle and Temperature Changes
Authors: Masuno Katsuya , Kumagai Shinya , Tashiro Kohji , Sasaki Minoru
Published: March 2011

A thermal infrared detector with enhanced contrast of its wavelength-selective function has been fabricated. A 2 ×2-mm2-size detector with p++-Si–Pt thermopiles on a Si substrate is the base device. A polymer material is deposited on the hot junctions of the thermopiles, working as a wavelength-selective absorber to integrate spectroscopic function into the thermopile detector. The polymer used is polyacrylonitrile (PAN), with a sharp isolated absorption peak at a wavelength of 4455 nm; the detector shows +35% output increase from the baseline at this wavelength. Very little dependence of the center wavelength (CWL) on the incident angle has been confirmed. Temperature dependencies were measured over the range from 20 to 80 °C. The detector shows a smaller CWL shift, which is ∼1/20 of that of the conventional detector using an optical bandpass filter with a dielectric multilayer on a Si substrate. These features are suitable for miniaturizing the sensor module including the optical setups.
Origin of Etch Hillocks Formed on On-Axis SiC(0001) Surfaces by Molten KOH Etching
Authors: Suda Jun , Shoji Haruki , Kimoto Tsunenobu
Published: March 2011

Molten KOH etching of 6H- and 4H-SiC0001 on-axis substrates was investigated. After molten KOH etching, etch pits originating from threading dislocations (TDs) and basal-plane dislocations (BPDs) were observed on (0001) surfaces. On the other hand, large and small hillocks were observed on (0001) surfaces. The etch hillocks consist of SiC, indicating slower etching at TDs. By comparing the (0001) side and (0001) side of the same substrate, it was found that large hillocks correspond to edge-type TDs, while small hillocks correspond to screw-type TDs.
Tight-Binding Approach to Initial Stage of the Graphitization Process on a Vicinal SiC Surface
Authors: Inoue Masato , Kangawa Yoshihiro , Wakabayashi Katsunori , Kageshima Hiroyuki , Kakimoto Koichi
Published: March 2011

We study the process of growth of graphene by the SiC surface decomposition method to improve the technique of growing graphene. In this study, the initial stage of the graphitization process on a periodically faceted SiC surface is investigated by the Naval Research Laboratory tight-binding approach. The results suggest that the decomposition of the SiC surface started by the desorption of Si atoms at the step edge. It is also found that released C atoms are trapped at the step-edge sites and that neighboring Si atoms are subsequently desorbed. These results suggest that graphene nucleation on the SiC surface proceeds in a negative step-flow mode.
Characterization of Plasma-Irradiated SiO2/Si Interface Properties by Photoinduced-Carrier Microwave Absorption Method
Authors: Hasumi Masahiko , Takenezawa Jun , Nagao Tomokazu , Sameshima Toshiyuki
Published: March 2011

We report photoinduced carrier recombination induced by 13.56 MHz radio frequency argon plasma treatment for samples of silicon substrates coated with thermally grown SiO2layers. The transmissivity of a 9.35 GHz microwave was measured and analyzed under illumination of 532 nm green light to the top or rear surface. Irradiation of argon plasma at 100 W for 5 min caused substantial carrier recombination. The recombination velocity of the plasma-irradiated surface was estimated to be 6000 cm/s. Investigation of 100 kHz capacitance response characteristics as a function of bias voltage for metal oxide p-type silicon structures revealed that irradiation of argon plasma increased the fixed charge density from 3.2×1011to 3.0×1012cm-2. Those changes were restored completely by heat treatment at 300 °C in air for 60 min.
Patterned Single-Wall Carbon Nanotube Transparent Conducting Films for Liquid Crystal Switching Electrodes
Authors: Lee Eun Hye , Ryu Je Hwang , Jang Jin , Park Kyu Chang
Published: March 2011

We have fabricated transparent and electrically conductive single-wall carbon nanotube (SWCNT) thin films for liquid crystal switching electrodes. The SWCNT film had a sheet resistance of 91.02 Ω/□ and a transmittance of 92.33% at 550 nm. Our CNT-based transparent conducting film (TCF) patterning technique is a combination of photolithography and O2 plasma etching. We were able to pattern CNT-TCFs with a high resolution, and as small as 4 µm, and to fabricate them with various shapes and patterns. Our CNT-TCFs were used to successfully switch liquid crystal cells with 100 µm and 15 mm line widths.
Driving Method for Compensating Reliability Problem of Hydrogenated Amorphous Silicon Thin Film Transistors and Image Sticking Phenomenon in Active Matrix Organic Light-Emitting Diode Displays
Authors: Shin Min-Seok , Jo Yun-Rae , Kwon Oh-Kyong
Published: March 2011

In this paper, we propose a driving method for compensating the electrical instability of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) and the luminance degradation of organic light-emitting diode (OLED) devices for large active matrix OLED (AMOLED) displays. The proposed driving method senses the electrical characteristics of a-Si:H TFTs and OLEDs using current integrators and compensates them by an external compensation method. Threshold voltage shift is controlled a using negative bias voltage. After applying the proposed driving method, the measured error of the maximum emission current ranges from -1.23 to +1.59 least significant bit (LSB) of a 10-bit gray scale under the threshold voltage shift ranging from -0.16 to 0.17 V.
Pixel-Level Digital-to-Analog Conversion Scheme with Compensation of Thin-Film-Transistor Variations for Compact Integrated Data Drivers of Active Matrix Organic Light Emitting Diodes
Authors: Kim Tae-Wook , Park Sang-Gyu , Choi Byong-Deok
Published: March 2011

The previous pixel-level digital-to-analog-conversion (DAC) scheme that implements a part of a DAC in a pixel circuit turned out to be very efficient for reducing the peripheral area of an integrated data driver fabricated with low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs). However, how the pixel-level DAC can be compatible with the existing pixel circuits including compensation schemes of TFT variations and IR drops on supply rails, which is of primary importance for active matrix organic light emitting diodes (AMOLEDs) is an issue in this scheme, because LTPS TFTs suffer from random variations in their characteristics. In this paper, we show that the pixel-level DAC scheme can be successfully used with the previous compensation schemes by giving two examples of voltage- and current-programming pixels. The previous pixel-level DAC schemes require additional two TFTs and one capacitor, but for these newly proposed pixel circuits, the overhead is no more than two TFTs by utilizing the already existing capacitor. In addition, through a detailed analysis, it has been shown that the pixel-level DAC can be expanded to a 4-bit resolution, or be applied together with 1:2 demultiplexing driving for 6- to 8-in. diagonal XGA AMOLED display panels.
6.0-Inch Extended Graphics Array Reflective Liquid Crystal Display Using Oxide Semiconductor Thin Film Transistors for Electronic Paper Display
Authors: Toyotaka Kouhei , Kusunoki Koji , Nagata Takaaki , Hirakata Yoshiharu , Wakimoto Kenichi , Koyama Jun , Yamazaki Shunpei , Sato Rai , Okazaki Kenichi , Sakakura Masayuki
Published: March 2011

We focused on the off-state current (I
off) of oxide semiconductor thin film transistors (TFT) (In–Ga–Zn-oxide TFTs), which is lower than that of amorphous silicon TFTs and successfully made a prototype of a 6.0-in. extended graphics array (XGA) reflective liquid crystal display (RLCD) panel integrally including a data selection demultiplexer and a scan driver and capable of displaying still images at 1/180 fps. When still images are displayed, the frame frequency can be set low. This means that the frequency of rewrites of image data is markedly reduced. This leads to the reduction in the power consumption of an LCD panel. Our panel can solve the problems of electronic paper displays: high drive voltage and difficulty of displaying moving images. Thus, our panel is suitable for electronic paper displays.
Proposal of Fast-Moving Ball Actuator Mode for Electronic-Paper Displays
Authors: Lee Jongmo , Keum Chang Min , Choi Hong , Park Hyojoo , Lee Donghyuck , Kim Weyong , Kim Byunguk , Hong Munpyo , Bae Byung Seong
Published: March 2011

We propose a new display mode using a fast-moving ball actuator (FMBA) for reflective electronic paper displays. To realize ball position stability, we developed a triangular wedge-shaped electrode instead of a conventional plane electrode. Using the wedge-shaped electrode we could achieve position stability of the ball and the operation voltage decreased from 60 to 40 V. Since the microballs move one by one, not collectively, the FMBA is free from agglomeration or lateral diffusion. Using the ball-by-ball display mode, the FMBA can achieve a fast response of less than 0.2 ms, as can be seen in quick-response liquid power displays (QR-LPDs). The FMBA can also provide a high resolution of displays over 6350 pixels per inch (PPI) for a pixel size of less than 4 µm and a ball of diameter of less than 1 µm. It is a major advantage for achieving a minute pixel size owing to the use of ball-by-ball displays.
Constant factor approximations for the hotlink assignment problem
Authors: Jacobs Tobias
Published: March 2011

The concept of
hotlink assignment
aims at reducing the navigation effort for the users of a Web directory or similar structure by inserting a limited number of additional hyperlinks called
hotlinks
. The
k
-hotlink assignment problem denotes the task of adding at most
k
outgoing hotlinks to each page of a tree-like site, minimizing the
path length
, that is, the expected number of “clicks” necessary for the user to reach her destination page. Another common formulation of this problem is to maximize the
gain
, that is, the path length reduction achieved by the assignment.

In this work we analyze the natural greedy strategy, proving that it reaches the optimal gain up to the constant factor of 2. Considering the gain, we also prove the existence of a PTAS. Finally, we give a polynomial-time 2-approximation for the 1-hotlink assignment problem, which constitutes the first constant factor approximation in terms of the path length. The algorithms' performance analyses are made possible by a set of three new basic operations for the transformation of hotlink assignments.
Set connectivity problems in undirected graphs and the directed steiner network problem
Authors: Chekuri Chandra , Even Guy , Gupta Anupam , Segev Danny
Published: March 2011

In the
generalized connectivity
problem, we are given an edge-weighted graph
G
= (
V
,
E
) and a collection
D
= {(
S
1
,
T
1
), …, (
S

k

,
T

k

)} of distinct
demands
each demand (
S

i

,
T

i

) is a pair of disjoint vertex subsets. We say that a subgraph
F
of
G
connects
a demand (
S

i

,
T

i

) when it contains a path with one endpoint in
S

i

and the other in
T

i

. The goal is to identify a minimum weight subgraph that connects all demands in
D
. Alon et al. (SODA '04) introduced this problem to study online network formation settings and showed that it captures some well-studied problems such as Steiner forest, facility location with nonmetric costs, tree multicast, and group Steiner tree. Obtaining a nontrivial approximation ratio for generalized connectivity was left as an open problem. We describe the first poly-logarithmic approximation algorithm for generalized connectivity that has a performance guarantee of
O
(log
2
n
log
2
k
). Here,
n
is the number of vertices in
G
and
k
is the number of demands. We also prove that the cut-covering relaxation of this problem has an
O
(log
3
n
log
2
k
) integrality gap.

Building upon the results for generalized connectivity, we obtain improved approximation algorithms for two problems that contain generalized connectivity as a special case. For the
directed Steiner network
problem, we obtain an
O
(
k
1/2 + ϵ
) approximation which improves on the currently best performance guarantee of
Õ
(
k
2/3
) due to Charikar et al. (SODA '98). For the
set connector
problem, recently introduced by Fukunaga and Nagamochi (IPCO '07), we present a poly-logarithmic approximation; this result improves on the previously known ratio which can be Ω(
n
) in the worst case.