bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Reconstruction of Three-Dimensional Objects in Integral Imaging using Lenslet Array
Authors: Shin Dong-Hak , Kim Eun-Soo , Lee Byoungho
Published: December 2005

In this paper, a new computational reconstruction technique for three-dimensional (3-D) objects in integral imaging using a lenslet array is proposed and its usefulness is discussed. Experimental results show that this technique improves the visual quality of a 3-D reconstructed image when compared with that of the conventional technique.
Analysis of the Dark-Current Density in Solar Cells Based on Multicrystalline SiGe
Authors: Ohdaira Keisuke , Usami Noritaka , Pan Wugen , Fujiwara Kozo , Nakajima Kazuo
Published: December 2005

We analyzed the dark-current density obtained from solar cells based on multicrystalline SiGe (mc-SiGe) using a modified two-diode model that includes two diodes with diode ideality factors of 1 and 2, shunt resistance, and several series resistances. The ratio of recombination area r, which corresponds to the domination of recombination current, is almost independent of the average Ge composition, while the shunt resistance R
sh shows little change up to 5% and a drastic reduction at an average Ge composition of 10%. These results indicate that the deterioration of solar cell properties with an average Ge composition of 10% is mainly due to its lower shunt resistance, which is caused by the generation of defects. It can also be said that the quality of mc-SiGe is preserved at an average Ge composition of up to 5%. This strongly supports the suitability to high-efficient solar cells of mc-SiGe that has the proper average Ge composition due to its enhanced absorption coefficient and the resultant increase in short-circuit current density.
Investigation of Transparent Conductive Oxide Al-Doped ZnO Films Produced by Pulsed Laser Deposition
Authors: Park Sang-Moo , Ikegami Tomoaki , Ebihara Kenji
Published: December 2005

High-quality transparent conductive aluminum-doped ZnO (AZO) thin films were deposited on quartz glass substrates using pulsed laser deposition (PLD). We varied the growth conditions in terms of substrate temperature and oxygen pressure. The crystallographic structure and electrical and optical properties of the as-grown AZO films were mainly investigated. In X-ray diffraction (XRD), (002) and (004) peaks were detected, indicating that Al doping did not cause structural degradation of wurtzite ZnO. The AZO films formed at a substrate temperature of 300°C showed a low electrical resistivity of 1.33×10-4 Ω cm, a carrier concentration of 1.25×1021 cm-3 and a carrier mobility of 37.6 cm2/(V s) at an oxygen pressure of 5 mTorr. A visible transmittance of above 88% was obtained. The AZO films show comparable electrical and optical properties to those of indium tin oxide (ITO) films and are emerging as a potential good challenger to ITO films.
Kinetic Analysis on the Photoluminescence Enhancement of 3-Mercaptopropyl Trimethoxysilane-Modified ZnS:Mn2+ Nanocrystal Colloidal Solution by Aging Effect
Authors: Sawada Naoki , Hattori Yasushi , Isobe Tetsuhiko , Takahashi Hisamitsu , Itoh Shigeo
Published: December 2005

The ZnS:Mn2+ nanocrystal colloidal solution is prepared by the in situ surface modification co-precipitation method in the presence of 3-mercaptopropyl trimethoxysilane (MPS). The increase in the fractional photoluminescence (PL) intensity by the aging of this solution is represented as a first-order reaction. Judging from the small activation energy, we conclude that Mn2+ ions are exchanged with Zn2+ ions at the surface of ZnS nanocrystals during aging to increase the PL intensity.
Curve Fitting of DC Field Dependence of Dielectric Constant of Barium Strontium Titanate Powder Prepared by Sol–Gel Process
Authors: Chen Yih-Chien , Huang Cheng-Liang
Published: December 2005

Effects of a DC-biasing field on the real part of the relative dielectric constant of barium strontium titanate powder prepared by the sol–gel process for application in phased array antennas have been studied. The real part of the relative dielectric constant of specimens decreases with increasing applied DC biasing field. An overall tunability of 15.7% at 1.5 kV/cm is achieved. The real part of the relative dielectric constant of specimens decreases rapidly before 1.0 kV/cm and slowly after 1.0 kV/cm when compared with the fitting data obtained by curve fitting with Johnson's bias equation. With the introduction of a bias exponent coefficient in the denominator of Johnson's bias equation, a modified bias equation is proposed. The data obtained by fitting with this proposed modified bias equation provide a more accurate description of the DC biasing field dependence behavior than those obtained by fitting with Johnson's bias equation.
Effect of CuO Additives on Sintering and Microwave Dielectric Behaviors of 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 Ceramics
Authors: Wang Jun-Jie , Hsu Cheng-Hsing , Huang Cheng-Liang , Lin Ruei-Jsung
Published: December 2005

Microwave dielectric properties of the complex perovskite compound CuO-doped 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics have been investigated using the conventional solid state method. Copper oxide effectively lowers the sintering temperature of 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics as a sintering aid. Ordering of structures was not observed at sintering temperatures from 1240 to 1360°C. The dielectric constant (ε
r) saturated at a value of 38–40 from 1270 to 1360°C. The Q×f values of 15000–70000 (at 7 GHz) can be obtained in all cases when the sintering temperatures are in the range of 1240–1360°C. The temperature coefficient of the resonant frequency τf was independent of the sintering temperature. An ε
r value of 39.7, a Q×f value of 70000 (at 7 GHz), and a τf value of 17 ppm/°C were obtained for 1 wt % CuO-doped 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics sintered at 1360°C for 2 h.
Microwave Dielectric Properties of MgNb2O6 Ceramics with Fe2O3 Additives
Authors: Hsu Cheng-Hsing , Tseng Ching-Fang , Huang Cheng-Liang
Published: December 2005

The dielectric properties and microstructures of MgNb2O6 ceramics with Fe2O3 additions (0.5–2 wt %) prepared with a conventional solid-state route have been investigated. It is found that MgNb2O6 ceramics can be sintered at 1140°C due to the liquid phase effect of Fe2O3 additions. At 1140°C, MgNb2O6 ceramics with 0.5 wt % Fe2O3 addition possess a dielectric constant (ε
r) of 20.5, a Q×f value of 70000 (9 GHz) and a temperature coefficient of resonant frequency (τf) of -49 ppm/°C. The Fe2O3-doped MgNb2O6 ceramics can find applications in microwave devices requiring low sintering temperatures.
Fabrication of Textured Bismuth Sodium Titanate Using Excess Bismuth Oxide
Authors: Kimura Toshio , Fukuchi Eiichiro , Tani Toshihiko
Published: December 2005

Bi0.5Na0.5TiO3 (BNT) bulk ceramics with a preferred <100> orientation (texture) were prepared by the reactive-templated grain growth method using platelike Bi4Ti3O12 (BiT) particles as templates for BNT. The texture did not develop extensively in stoichiometric BNT, but the addition of excess Bi2O3 to BNT enhanced the texture development. The role of excess Bi2O3 was examined. The calcined compacts were composed of matrix grains with random orientation and <100>-oriented grains transformed from aligned BiT particles, and texture developed by the preferential growth of oriented grains at the expense of matrix grains. In stoichiometric BNT, the growth rate of matrix grains was high and the conditions for the preferential growth of the oriented grains were disrupted. Excess Bi2O3 reduced grain growth rate, and the conditions for preferential growth were maintained, resulting in the development of highly textured BNT. The resultant textured BNT ceramic exhibited 70% higher piezoelectric d
31 and electromechanical k
p coefficients than nontextured BNT.
Preparation, Characterization and Microwave Dielectric Properties of A2BWO6 (A=Sr, Ba; B=Co, Ni, Zn) Double Perovskite Ceramics
Authors: Zhao Fei , Yue Zhenxing , Gui Zhilun , Li Longtu
Published: December 2005

The A2BWO6 (A=Sr, Ba; B=Co, Ni, Zn) microwave dielectric ceramics were prepared by conventional solid-state ceramic route. According to the X-ray diffraction (XRD) results, the ceramics have cubic perovskite structure for all compounds. In addition, the Ni-containing compounds showed apparent supperlattice reflections at low angles, whereas the others didn't. The results of Raman spectroscopy show that the degree of B-site ordering is different with different B2+ ions. The dielectric properties of the ceramics were measured in the frequency range 6.5 to 8.5 GHz using resonance methods. The ceramics have dielectric constant in the range 18 to 30, high quality factor (Q×f value up to 56000 GHz) and negative temperature coefficient of resonant frequencies in the range -72.9 to -31.1 ppm/°C. The dielectric constant increased with increasing B2+ ionic polarizability, and the quality factor was enhanced due to the increase in B-site ordering. The relationship between temperature coefficient of dielectric constant and tolerance factor was accordant in comparison with the other perovskites.
Internal Friction Peak in FCC Fe–Cr–Ni Alloys Hydrogen-Charged by Gas-Equilibration Method
Authors: Ide Naoki , Naito Toyoki , Asano Shigeru
Published: December 2005

An internal friction peak due to hydrogen in Fe55Cr45-x
Ni
x
(x=20–45) and Fe100-x
Ni
x
(x=35–100) alloys was observed. A gas-equilibration method was employed in order to charge specimens homogeneously with hydrogen. In Fe55Cr45-x
Ni
x
alloys, the peak height significantly increased as the nickel content increased, whereas in Fe100-x
Ni
x
alloys the peak height did not show a monotonic change versus the increasing nickel content. In both alloys the peak height depended strongly on the alloy composition.
Reaction of Hydrogen-Terminated Si(100) Surfaces with Oxygen at Very Low Pressures during Heating
Authors: Urabe Shinichi , Nishimura Kazuo , Nishikawa Syuhei , Morita Satoru , Morita Mizuho
Published: December 2005

Reactions of hydrogen-terminated Si(100) surfaces with oxygen at very low pressures during heating are characterized by a method that combines heating and cooling in thermal desorption spectroscopy. Surface hydrogen coverage as a function of temperature is estimated from the hydrogen desorption spectrum obtained by the combination measurement. The surface coverage under the condition with or without introducing oxygen gas indicates that the hydrogen of silicon monohydride begins to desorb after almost half the hydrogen of silicon dihydride desorbs. The hydrogen desorption behavior under the introduction of oxygen gas suggests that bonding between Si and hydrogen atoms for silicon monohydride at the Si(100) surface is stabilized by adsorption of oxygen atoms on surface Si back bond sites during heating.
Variation in 111 d-Space and Generation of Hillocks in Platinum Thin-Film Electrodes by Heat Treatment
Authors: Nakamura Kimitoshi , Otani Yohei , Kurita Masaaki , Okamura Soichiro , Shiosaki Tadashi
Published: December 2005

The variation in 111 d-space of Pt thin-film electrodes during heat treatment was precisely measured by an X-ray diffraction system with a heating stage. The 111 d-space of Pt films deposited at 200°C linearly increased as the temperature was increased to 450°C and was almost constant over the temperatures range from 450 to 600°C due to stress relaxation. The generation of hillocks was observed in the Pt films which were relaxed in this way. On the other hand, in the case of Pt films deposited at temperatures higher than 500°C, the d-space linearly increased and then linearly decreased to almost the same value in the heat treatment at a maximum temperature of 600°C, and no hillocks were observed on the surface after the heat treatment. Furthermore, Pt films prepared at room temperature (RT) at different deposition rates showed different variations in d-space and different sizes of hillocks. These results suggest that knowing the variation in 111 d-space during heat treatment is beneficial for predicting the generation of hillocks in 111-oriented Pt thin films.
Blueshift of Fluorinated Amorphous Carbon Films by Fourier Transform Infrared Spectroscopy
Authors: Oh Teresa
Published: December 2005

The chemical shift of organic materials is one of the important factors in view of the bonding structure, and an amorphous bonding structure in low-dielectric-constant materials is a basic requirement for decreasing the dielectric constant. The chemical shift originates from the conjugated C=C bond and the peculiar phenomenon of the appearance of the terminal C–H bond due to neighboring highly electronegative atoms during the deposition of fluorinated amorphous carbon films. The blueshift due to the condensation of the C–H bond was researched in fluorinated amorphous carbon films, but the redshift due to the elongation of the C–H bond was not observed because the broken C–H bond by fluorine attack becomes an HF bond and evaporates. The breaking of the cross-link structure can be accelerated by annealing and the lowest dielectric constant of the films is 1.98 at the as-deposited film with the cross-link amorphous structure.
Atomic Force Microscope Topography of Nickel-Affected MoS2 Model Catalysts
Authors: Uetsuka Hiroshi , Ikeda Satoshi , Sakama Hiroshi , Sakashita Yukio , Onishi Hiroshi
Published: December 2005

Nanometer-sized particles of MoS2 were synthesized on mica and MoS2 surfaces and observed using an atomic force microscope. Molybdenum oxide was deposited on each substrate and sulfided with H2S gas to simulate catalysts used in petroleum refining. The height of the sulfided particles was regulated to be single or double layers of S–Mo–S suggesting basal-bonded, flat-lying MoS2. When Ni metal was simultaneously deposited with molybdenum oxide, the sulfided particles remained basal-bonded and the number of stacked layers increased by one or two.
Observation of Two Phases of Neutron Emission in a Low Energy Plasma Focus
Authors: Yap S. L. , Wong C. S. , Choi P. , Dumitrescu C. , Moo S. P.
Published: December 2005

Neutron emissions in a low energy 3.3 kJ (15 kV) plasma focus are studied. The system is operated in deuterium and deuterium-argon admixtures. Enhancement of the neutron yield is obtained with a suitable amount of highZadmixture. Time resolved neutron measurements are made by using four detectors positioned at two different distances at both the end-on and side-on direction. Maxwellian pulse fitting techniques are employed to resolve a two phase neutron emission history. The neutron energy and anisotropy for the two phases are determined. The energy and anisotropy of the two phases are found to be different and that the second phase is of high anisotropy. These results confirm the presence of two phases of neutron emission that are possibly due to at least two different kinds of neutron production mechanisms in the low energy plasma focus.
Production of 70Zn Beam from RIKEN 18 GHz Electron Cyclotron Resonance Ion Source
Authors: Higurashi Yoshihide , Kidera Masanori , Nakagawa Takahide , Aihara Toshimitsu , Kase Masayuki , Goto Akira , Yano Yasushige
Published: December 2005

We produced an intense beam of Zn14+–16+ ions from the RIKEN 18 GHz electron cyclotron resonance ion source by inserting a ZnO rod into the plasma directly. This method was successfully applied to produce the intense beam of 70Zn16+ for searching for a superheavy element (atomic number of 113).
Enhanced Electrochemiluminescence by Use of Nanoporous TiO2 Electrodes: Electrochemiluminescence Devices Operated with Alternating Current
Authors: Kado Takashi , Takenouchi Masatoshi , Okamoto Seiichi , Takashima Wataru , Kaneto Keiichi , Hayase Shuji
Published: December 2005

It was found that electrochemiluminescence is enhanced by the use of nanoporous TiO2 electrodes. The nanoporous TiO2 electrodes were fabricated by cumulating nano-TiO2 crystals on the transparent conductive layers (SnO2/F). The device was composed of the porous TiO2 electrodes (10 µm) and SnO2/F electrodes as counterelectrodes. The gap was filled with electrolytes containing Ru(bpy)3(PF6)2 (bpy: bi-pyridyl) in various solvents. The electrochemiluminescence was much larger than that from the cell composed of two flat SnO2/F electrodes. It is likely that the increase in elecrochemiluminescence is associated with the nanopores as well as with the large surfaces of porous semiconductive oxide electrodes.
Lasing from Thick Anisotropic Layer Sandwiched between Polymeric Cholesteric Liquid Crystal Films
Authors: Song Myoung Hoon , Park Byoungchoo , Takanishi Yoichi , Ishikawa Ken , Nishimura Suzushi , Toyooka Takehiro , Takezoe Hideo
Published: December 2005

We have demonstrated a new type of lasing mode in a dye-doped 100-µm-thick nematic liquid crystal layer sandwiched between two polymeric cholesteric liquid crystal films functioning as a photonic crystal. The fabricated cell exhibits several characteristic dips in the transmittance spectrum in addition to fine fringes originating from a Fabry–Perot cavity mode. These dips are due to the phase retardation between optical eigenmodes in the birefringent medium, which is not realized in an isotropic layer. The cell shows multimode lasing at wavelengths corresponding to transmittance maxima within the stopband region when the nematic layer is doped with dyes.
New Technique for Evaluating Adhesion Properties between Soft Materials
Authors: Sato Takaya , Goto Motoaki , Nakano Ken , Suzuki Atsushi
Published: December 2005

A new, simple apparatus for measuring the surface adhesion properties of soft materials was designed, where the adhesion force of a point contact between soft materials and the total energy required to separate the contact can be measured using the springs of phosphor–bronze thin plates with strain gauges. The adhesion between swollen hydrogels was studied here by this simple technique in air at room temperature. The gels used in the present preliminary experiments were poly(sodium acrylate) hydrogels physically cross-linked by aluminum ions. The adhesion force and the separation energy showed a power-law increase with separation velocity. The apparatus was applied to evaluate the adhesion properties of seven anti-inflammatory analgesic cataplasms on the market. It was found that the easiness to separate (rank of adhesion force and the separation energy) was consistent with the results of those obtained by organoleptic evaluations.
Beam Stability Improvement of a Liquid Metal Ion Source
Authors: Hyun Jeong Woo , Yim Youn Chan , Kim Seong Soo , Oh Hyun Joo , Park Cheol Woo , Choi Eun Ha , Seo Yoonho , Kang Seung Oun
Published: December 2005

Previous studies on liquid gallium ion sources used an electrochemically etched tungsten wire with a coil-type heater. Such a structure requires excessive power consumption in the course of heating the liquid metal. In this study, a new structure is proposed that replaces the coil-type heater. It uses a gallium reservoir made of six pre-etched 250 µm tungsten wires that surround the needle electrode. Gallium loading at the reservoir is observed to be much more stable, resulting in an improved beam stability.
Nanoimprint and Lift-Off Process Using Poly(vinyl alcohol)
Authors: Nakamatsu Ken-ichiro , Tone Katsuhiko , Matsui Shinji
Published: December 2005

We developed a lift-off process for a nanoimprint lithography (NIL) using poly(vinyl alcohol) (PVA) as the replicated material. PVA could easily be dissolved in water. A conventional lift-off process using poly(metyl methacrylate) (PMMA) uses acetone as a solvent, while the lift-off process using PVA uses water as a solvent, which is an ecologically friendly process. We demonstrated Au patterns with sub-µm dimensions using a lift-off process with a PVA single layer. In addition, an Hydrogen silsesquioxane (HSQ)/PVA bilayer structure was used for the lift-off process. This bilayer structure could be fabricated by room-temperature NIL and dry etching. Au patterns were easily obtained using the bilayer structure having an inverse tapered shape. In the lift-off process without using HSQ/PVA bilayer, Au wiring with sub-µm linewidth could be obtained, however, 100-nm-linewidth patterns did not remained. Line-and-spacing gratings of 100 nm in the Au patterns were demonstrated using the water lift-off process with the HSQ/PVA bilayer structure.
A Simple Technique to Measure the Friction Coefficient between Polymer Network of Hydrogel and Water
Authors: Yoshikawa Muneyuki , Ishii Ryota , Matsui Jun , Suzuki Atsushi , Tokita Masayuki
Published: December 2005

A simple apparatus to control water flow through a hydrogel at a fixed temperature was designed, in which the hydrogel was mechanically constrained in a glass microcapillary at gelation. An evaluation of the friction between the polymer network of polyacrylamide gels and the solvent water measured by this simple technique is presented here. The effects of the experimental conditions, the pressure applied to the solvent, the temperature and the gel size (the length and the cross-sectional area), on the friction coefficients were examined. The results agreed well with the model of the flux of water flow in a capillary based on the Hagen–Poiseuille equation.
Ultrafast Electronic Excitation in CaF2 Crystals
Authors: Xu Shizhen , Jia Tianqing , Li Xiaoxi , Feng Donghai , Sun Haiyi , Li Chengbin , Wang Xiaofeng , Kuroda Hirao , Li Ruxin , Xu Zhizhan
Published: December 2005

A new pump and probe experimental system was developed, the pump pulse duration of which is stretched and is much longer than that of the probe pulse. Using this system, time-resolved electronic excitation processes and damage mechanisms in CaF2 crystals were studied. The measured reflectivity of the probe pulse begins to increase at the peak of the pump pulse and increases rapidly in the latter half of the pump pulse, when the pump pulse duration is stretched to 580 fs. Our experimental results indicate that both multiphoton ionization and impact ionization play important roles in the generation of conduction band electrons, at least they do so when the pump pulse durations are equal to or longer than 580 fs.
Variations in Cerium X-ray Spectra and Enhanced K-Edge Angiography
Authors: Sato Eiichi , Tanaka Etsuro , Mori Hidezo , Kawai Toshiaki , Inoue Takashi , Ogawa Akira , Yamadera Akira , Sato Shigehiro , Ito Fumihito , Takayama Kazuyoshi , Onagawa Jun , Ido Hideaki
Published: December 2005

A cerium-target X-ray tube is useful in performing cone-beam K-edge angiography because K-series characteristic X-rays from the cerium target are absorbed effectively by iodine-based contrast media. The X-ray generator consists of a main controller and a unit with a high-voltage circuit and a fixed anode X-ray tube. The tube is a 1.0-mm-focus diode with a cerium target and a 0.5-mm-thick beryllium window. The maximum tube voltage and current were 65 kV and 0.4 mA, respectively. Cerium Kα rays were selected out using a barium sulfate filter, and the X-ray intensities without filtering and with a barium sulfate filter were 209 and 16.8 µGy/s, respectively, at 1.0 m from the source with a tube voltage of 60 kV and a current of 0.40 mA. Angiography was performed with an X-ray film using the filter and iodine-based microspheres 15 µm in diameter. In the angiography of nonliving animals, we observed fine blood vessels approximately 100 µm in diameter with high contrasts.
Effect of Laser Irradiation on Enzyme Activity
Authors: Murakami Satoshi , Kashii Masafumi , Kitano Hiroshi , Adachi Hiroaki , Takano Kazufumi , Matsumura Hiroyoshi , Inoue Tsuyoshi , Mori Yusuke , Doi Masaaki , Sugamoto Kazuomi , Yoshikawa Hideki , Sasaki Takatomo
Published: December 2005

We previously developed a protein crystallization technique using a femtosecond laser and protein crystal processing and detaching techniques using a pulsed UV laser. In this study, we examine the effect of laser irradiation on protein integrity. After several kinds of laser were irradiated on part of a solution of glycerol-6-phosphate dehydrogenase from Leuconostoc mesenteroides, we measured the enzyme activity. Femtosecond and deep-UV laser irradiations have little influence on the whole enzyme activity, whereas the enzyme lost its activity upon high-power near-infrared laser irradiation at a wavelength of 1547 nm. These results suggest that suitable laser irradiation has no remarkable destructive influence on protein crystallization or crystal processing.
Effects of High-Density Oxygen Plasma Posttreatment on Field Emission Properties of Carbon Nanotube Field-Emission Displays
Authors: Juan Chuan-Ping , Tsai Chun-Chien , Chen Kuei-Hsien , Chen Li-Chyong , Cheng Huang-Chung
Published: December 2005

The effects of oxygen plasma posttreatment (PPT) on the morphology and field emission properties of carbon nanotube (CNT) arrays grown on silicon substrates are proposed and experimental results are reported. Oxygen PPT led to an enhancement in the emission properties of CNTs, which showed an increase in total emission current density and a decrease in turn-on field after plasma treatment. Scanning electron microscopy (SEM) images showed reduced densities of the CNTs, which resulted in a decrease of the screening effect in the electric field. Raman spectra showed an increase in the number of defects which served as field-emission sites when the plasma power or treatment time with the plasma increased. Transmission electron microscopy (TEM) images were used to identify the quality of the nanotubes, so that we could clearly find evidences of improvement in the field emission properties after plasma treatment. The measurement of electrical characteristics revealed improved field emission properties under proper plasma conditions. The turn-on field decreased from 4.8 to 2.5 V/µm, and the emission current density increased from 78.7 µA/cm2 to 18 mA/cm2 at an applied field of 5.5 V/µm.
Difference in Self-Assembling Morphology of Peptide Nanorings
Authors: Okamoto Hajime , Yamada Tetsuo , Miyazaki Hiroshi , Nakanishi Tsutomu , Takeda Kyozaburo , Usui Kenji , Obataya Ikuo , Mihara Hisakazu , Azehara Hiroaki , Mizutani Wataru , Hashimoto Katsushi , Yamaguchi Hiroshi , Hirayama Yoshiro
Published: December 2005

We synthesized the peptide nanorings of cyclo[-(D-Ala-L-Gln)3], cyclo[-(D-Cys-L-Gln)3], cyclo[-D-Cys-L-His-D-Ala-L-Asn-Gly-L-Gln-] and cyclo[-(L-Gln)5], and studied the way in which the difference in the type and/or number of component amino acid residues changes the self-assembling morphology of the nanorings on gold substrates by atomic force microscopy. The study revealed that cyclo[-(D-Ala-L-Gln)3] formed nanotube bundles through inter-ring hydrogen bonds, while the nanorings of cyclo[-(D-Cys-L-Gln)3] adhered to the gold surface directly due to the high affinity of thiol to gold. In contrast, a random amino acid sequence of cyclo[-D-Cys-L-His-D-Ala-L-Asn-Gly-L-Gln-] resulted in many isolated nanotubes, which were first observed in the present study. While the D,L-peptide nanotubes have very straight forms, the homo-L-peptide of cyclo[-(L-Gln)5] formed interesting randomly branching nanotubes that were entwined and grew on the substrate. Scanning tunneling microscopy was also performed and high-resolution images of both the peptide nanotubes and the nanotube bundles were obtained.
Nanoindentation Test for Evaluating Intermolecular Elastic and Plastic Characteristics of Copper Phthalocyanine Thin Films
Authors: Kanari Moriyasu , Karino Yoichi , Wakamatsu Takashi
Published: December 2005

We present the elastic and plastic parameters and the deformation patterns of a copper phthalocyanine (CuPc) thin film as compared with those of a polyester (PE) film and a metal copper (Cu) bulk. The yield stress of the CuPc film, σY=51.9 MPa, was comparable to that of the PE film and was lower by a factor of 10 than that of the Cu bulk. In contrast, Young's modulus, E
S=9.29 GPa, of the CuPc film was intermediate between those of the PE film and Cu bulk, and the shearing strain energy per unit volume, U
S=8.74×1023 eV/m3, was lower by a factor of 10 than those of these two materials. The load–displacement (P–h) curves of the CuPc film were similar to those of the Cu bulk, in contrast to those of the vsicoelastic PE film, indicating that these deformation patterns showed an elastoplastic behavior and could be expressed by the Maxwell model.
Cleaning Method for Thickness Metrology of SiO2 Thin Films on Si Substrates by Heating in Atmosphere
Authors: Azuma Yasushi , Fujimoto Toshiyuki , Kojima Isao
Published: December 2005

In order to evaluate accurately the thickness of SiO2 films on Si substrates, we applied a heat cleaning method in the atmosphere to remove adsorbates on the SiO2 surface using a hot plate. A high reproduciblity was obtained for the thicknesses of the sample just after heating. In addition, carbon-derived contaminants on the surface were markedly decreased by the heating. Since this method is extremely simple and requires no special equipment and chemicals, it has a potential to become an effective cleaning method for accurate thickness evaluation of SiO2 thin films on Si substrates.
Estimation of Ligand–Receptor Binding Affinity from Fluctuation of Their Interface
Authors: Iwamoto Koji , Ode Hirotaka , Ohta Masami , Misu Takashi , Hata Masayuki , Neya Saburo , Hoshino Tyuji
Published: December 2005

It is necessary for the understanding of protein interactions or in silico drug designs to accurately estimate ligand–receptor affinity. The energy calculation based on the electrostatic force, van der Waals force, and solvation effect is a direct method of computing the magnitude of the interaction between ligand and receptor. By this conventional method, however, it is difficult to estimate a slight difference in binding affinity with sufficient accuracy. We propose a novel concept for the evaluation of binding affinity between a ligand and its receptor by functionalizing the fluctuation at the ligand–receptor interface. This method enables an adequate estimation with a high accuracy compared with the conventional energetic approach. Human immunodeficiency virus type 1 (HIV-1) protease and its inhibitor are used to explain how binding affinity is extracted from the fluctuation in interfacial energy, and a combination of an antigen and its antibody is examined to demonstrate the compatibility between the estimation from the interfacial fluctuation and the experimentally measured binding energy.
Formation and Thermal Stability of Nickel Germanide on Germanium Substrate
Authors: Zhang Qingchun , Wu Nan , Osipowicz Thomas , Bera Lakshmi Kanta , Zhu Chunxiang
Published: December 2005

The formation and thermal stability of nickel germanide on germanium substrate were examined by both electrical and physical characterization methods. Low resistivity (14 µΩ cm) mono-nickel–germanide was formed at a low temperature of 400°C on Ge substrate. The sheet resistance of nickel germanide changed with the germanide formation temperatures and had a similar characteristic as nickel silicide. However, the thermal stability study shows that NiGe formed on Ge substrate has a poorer thermal stability than NiSi on Si substrate, which is due to the lower activation energy of agglomeration in NiGe (2.2±0.2 eV) compared to NiSi.
Temperature-Dependent Contrasts of Lateral p+–n Junctions on H/Si(100) Imaged with Photoemission Electron Microscopy
Authors: Fukidome Hirokazu , Yoshimura Masamichi , Ueda Kazuyuki
Published: December 2005

The temperature dependence of contrasts on a H/Si(100) surface with lateral p
+–n junctions has been studied for the first time by photoemission electron microscopy. It is found that the intensity ratio of photoelectrons from the p
+-region to that from the n-region varies with temperature. This temperature dependence arises mainly from the change in the band bending of n-region. The change can be qualitatively explained by the balance between the higher pinned position of Fermi level induced by hydrogen-termination and surface photovoltage, followed with the further shift of the pinned Fermi level to intrinsic one at higher temperatures.
Coherent 589-nm-light Generation by Quasi-Intracavity Sum-Frequency Mixing
Authors: Saito Norihito , Akagawa Kazuyuki , Hayano Yutaka , Saito Yoshihiko , Takami Hideki , Iye Masanori , Wada Satoshi
Published: December 2005

We demonstrated a simple configuration for high-power 589-nm-light generation by sum-frequency mixing using 1064 and 1319 nm Nd:YAG lasers in continuous-wave oscillation. A periodically-poled KTiOPO4 crystal was set in the 1064 nm laser and a 1319 nm beam emitted from an independently constructed Nd:YAG laser was input in the 1064 nm laser from outside of it. An output power of 980 mW at 589 nm was obtained and the output power was 8 times higher than that in extracavity sum-frequency generation using the same apparatus.
Sub-5-fs Pulse Compression of Laser Output Using Photonic Crystal Fiber with Short Zero-Dispersion Wavelength
Authors: Adachi Muneyuki , Yamane Keisaku , Morita Ryuji , Yamashita Mikio
Published: December 2005

Output pulses from a photonic crystal fiber (PCF) with a zero-dispersion wavelength (ZDW: 853 nm) were compressed to 5.8 fs by feedback spectral-phase compensation. Furthermore, for another PCF with a shorter ZDW (744 nm), whose output spectral-phase measurement and pulse compression are generally thought to be difficult because of coherence degradation between pulses, we measured successfully their phases in the entire spectral region (480 to 1000 nm) by a suitable selection of input pulse and fiber parameters. The pulse compression experiment using an improved feedback system showed that in the short-wavelength region, pulses can be compressed to 4.9 fs, whereas in the entire spectral region, pulses cannot be compressed. This is because the visibility of the spectral interferogram in the spectral-phase interferometry for direct electric-field reconstruction (SPIDER) signal in the longer-wavelength region corresponding to the phase-sensitive soliton-breaking-up region is degraded by large phase modulation using a spatial light modulator.
Scanning Tunneling Microscopy Observation of Individual Boron Dopant Atoms beneath Si(001)-2×1 Surfaces
Authors: Nishizawa Masayasu , Bolotov Leonid , Kanayama Toshihiko
Published: December 2005

Individual B dopant atoms residing beneath Si(001)-2×1 surfaces have been detected by scanning tunneling microscopy (STM). A subsurface B atom appears as a broad protrusion in filled-state images, while it appears as either a broad depression or a localized protrusion in empty-state images depending on the STM tip condition. This variation in dopant appearance is attributed to the different work function (WF) of the tip, i.e., the amount of tip-induced band bending differs depending on the tip WF, resulting in a different tunneling path and an opposite dopant appearance under the same bias voltage.
Perovskite Single-Phase Growth of Epitaxial Pb(Zn1/3Nb2/3)O3 Films by Alternative-Source-Gas-Introduced Metalorganic Chemical Vapor Deposition
Authors: Yokoyama Shintaro , Okamoto Satoshi , Saito Keisuke , Uchida Hiroshi , Koda Seiichiro , Funakubo Hiroshi
Published: December 2005

Relaxor-type ferroelectric Pb(Zn1/3Nb2/3)O3 [PZN] films were prepared on (100), (110), (111)SrTiO3 and MgO substrates by metalorganic chemical vapor deposition (MOCVD). The dependences of the constituent phase of the deposited films on the sequence of gas introduction in the MOCVD and on the kinds of substrates and the orientation of the substrates were investigated systematically. Compared with continuous and pulsed sequences of source gas introduction, an alternative sequence of source gas introduction of the Pb and Zn+Nb, named alternative MOCVD, produces a higher phase purity of perovskite for film deposited on (100)MgO substrates. In addition, the phase-pure perovskite PZN film was first grown on (110) and (111)MgO substrates. This is due to the relatively smaller lattice mismatch between the perovskite PZN and the substrate than that between an impurity phase, pyrochlore, and substrates that exists when films are deposited on these substrates. This is the first reported deposition of the pyrochlore-free phase-pure epitaxial PZN films.
A Palm-Size Ultraviolet Laser Using a Combination of a Monolithic Wavelength Converter and an Optical Fiber
Authors: Hatano Satoshi , Ito Satoshi , Yoshimura Masashi , Mori Yusuke , Sasaki Takatomo
Published: December 2005

We have developed a monolithic wavelength converter which is composed of optically contacted KTiOPO4 and Gd
x
Y1-x
Ca4O(BO3)3. It generates an ultraviolet (UV) light at 0.355 µm just by the incidence of a near-infrared laser at 1.064 µm. Moreover, the converter is attached to the end of an optical fiber which is delivering a near-infrared light to fabricate an extremely compact UV laser. A palm-size UV laser generates an output power of 120 mW at a repetition rate of 60 kHz.
Growth and Electrical Characterization of N-face AlGaN/GaN Heterostructures
Authors: Rajan S. , Wong M. , Fu Y. , Wu F. , Speck J. S. , Mishra U. K.
Published: December 2005

We describe growth and characterization of N-face GaN-based high electron mobility structures using plasma-assisted molecular beam epitaxy (MBE) on C-face SiC substrates. A two-step buffer approach consisting of a low Ga-flux followed by high Ga-flux was used to achieve smooth morphologies and threading dislocation (TD) densities as low as 1.5×1010 cm-2. These TD densities are comparable to the lowest achieved on Ga-face GaN grown by MBE on Si-face SiC. Secondary ion mass spectrometry measurements were carried out to study O, C, and Si incorporation. Hall, capacitance–voltage and transfer length method measurements on GaN/AlGaN/GaN modulation-doped heterostructures were found to match simulations, and a charge of 1×1013 cm-2 with electron mobility above 1000 cm2 V-1 s-1 was measured.
Terahertz Transmission Property of a Thin Metal Hole-Array Filter
Authors: Akazawa Masamichi , Yamazaki Yusuke , Sano Eiichi
Published: December 2005

We studied THz transmission characteristics of a thin metal hole-array filter whose thickness was much smaller than the transmitted wavelength, based on the time-domain sampling. A high transmittance was observed in a passband without a waveguide-like cutoff frequency. Tilting incident angle resulted in splits of the transmission peak. Time-domain waveforms of the transmitted waves indicated the stagnation having frequency-spectrum components in the passbands. Participation of surface plasmon–polaritons in the transmission process is discussed.
Synchronization of 1064 and 1319 nm Pulses Emitted from Actively Mode-Locked Nd:YAG Lasers and Its Application to 589 nm Sum-Frequency Generation
Authors: Saito Norihito , Akagawa Kazuyuki , Hayano Yutaka , Saito Yoshihiko , Takami Hideki , Iye Masanori , Wada Satoshi
Published: December 2005

Sum-frequency generation was carried out by mixing 1064 and 1319 nm pulses emitted from actively mode-locked neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers for efficient 589 nm light generation. A radio frequency of approximately 75 MHz was split into two and fed to acousto-optic mode lockers of two lasers for mode-locked operation. The synchronization of the pulses was achieved by controlling the phase difference between the radio frequencies. The maximum output power at 589 nm reached 260 mW, which corresponded to an energy conversion efficiency of more than 13%. The output power was 3.8-fold that in continuous-wave operation.
Electronic Structure in Valence Band of Nd-Substituted Bi4Ti3O12 Single Crystal Probed by Soft-X-Ray Emission Spectroscopy
Authors: Higuchi Tohru , Noguchi Yuji , Goto Takashi , Miyayama Masaru , Shin Shik , Kaneda Kazuhiro , Hattori Takeshi , Tsukamoto Takeyo
Published: December 2005

The electronic structure of Nd3+-substituted Bi4Ti3O12 single crystals was studied by soft-X-ray emission spectroscopy. The valence band is in good accordance with the band calculation. The valence band is mainly composed of the O 2p state hybridized with Ti 3d and Bi 6s states. The hybridization effect between the Ti 3d and O 2p states increases with Nd3+ substitution, indicating a change in Ti–O bond length in the a–b plane. The hybridization effect between the Bi 6s and O 2p states decreases with Nd3+ substitution. The Bi–O hybridization effect is considered to be closely related to the ferroelectric behavior.
High Sensitivity InSb Hall Effect Biosensor Platform for DNA Detection and Biomolecular Recognition Using Functionalized Magnetic Nanobeads
Authors: Togawa Kiyoshi , Sanbonsugi Hideaki , Sandhu Adarsh , Abe Masanori , Narimatsu Hiroki , Nishio Kousuke , Handa Hiroshi
Published: December 2005

A compact, high sensitivity and low cost biosensing platform based on InSb thin film micro-Hall effect biosensors [30 ×30 µm2; magnetic field sensitivity of 1.8 nT/(Hz)1/2] was developed and used for the detection of DNA molecules labeled with magnetic beads. Magnetic beads (∼200 nm diameter) were functionalized and selectively immobilized onto Hall biosensor surfaces via highly specific hybridization of complementary oligonucleotides and subsequently detected by magnetic susceptibility measurements. The potential for parallel biomolecular analysis with 5 ×5 µm2 linear sensor arrays was demonstrated.
Heteroepitaxial Growth of Rutile TiO2 on GaN(0001) by Pulsed Laser Deposition
Authors: Hitosugi Taro , Hirose Yasushi , Kasai Junpei , Furubayashi Yutaka , Ohtani Makoto , Nakajima Kiyomi , Chikyow Toyohiro , Shimada Toshihiro , Hasegawa Tetsuya
Published: December 2005

Rutile TiO2(100) thin films have been grown on GaN(0001) surfaces by using the pulsed laser deposition method. Reflection high-energy electron diffraction (RHEED) measurements during the deposition clearly revealed the layer-by-layer growth of TiO2 at a substrate temperature of 400°C under an oxygen pressure of 1×10-5 Torr. X-ray diffraction and atomic force microscopy confirmed that the obtained films have high crystallinity with atomically flat surfaces. Pole figure measurements revealed the epitaxial relationship between TiO2 and GaN, namely that the in-plane TiO2<010> axis aligns parallel to the GaN<1010>.
Structural and Luminescence Properties of InAs Quantum Dots: Effect of Nitrogen Exposure on Dot Surfaces
Authors: Sasikala Ganapathy , Suemune Ikuo , Thilakan Periyasamy , Kumano Hidekazu , Uesugi Katsuhiro , Nabetani Yoichi , Matsumoto Takashi , Machida Hideaki
Published: December 2005

The role of nitrogen (N) in InAs quantum dots (QDs) surfaces was studied by supplying a nitrogen (N) precursor to InAs QDs surfaces just before burying them under GaAs capping layers. Monomethylhydrazine was used as the N precursor. InAs QDs treated by such N exposure of their upper surfaces showed the following distinct improvements in their uniformity and efficiency: the peaks of histograms showing QD size distributions observed by atomic-force microscopy became narrower. Photoluminescence (PL) subpeaks originating from QD energy states showed clearer structures. The full widths at half maximum of the PL linewidths were reduced to 20 meV at room temperature, which is among the lowest reported. In addition to these observations of higher QD uniformities, the thermal activation energy for the temperature dependence of integrated PL intensity increased from 150 to 310 meV and also the PL efficiency increased ∼6-folds with the N-exposure of the InAs QD surfaces. The role of N in these marked improvements in characteristics was discussed on the basis of valence-force field model calculations.
Control of p-Type Conduction in a-Plane GaN Grown on Sapphire r-Plane Substrate
Authors: Tsuchiya Yosuke , Okadome Yoshizane , Honshio Akira , Miyake Yasuto , Kawashima Takeshi , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu
Published: December 2005

Mg-doped p-type a-plane GaN films were grown on high-quality unintentionally doped GaN on +0.5°-off r-plane sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). A maximum hole concentration of 2.0×1018 cm-3 was reproducibly achieved at room temperature, which was higher than the maximum hole concentration of p-type c-plane GaN. The activation energy of Mg acceptors in p-type a-plane GaN with a hole concentration of 2.0×1018 cm-3 was found to be 118 meV by temperature-dependent Hall-effect measurement.
Fabrication of Semi-Insulating GaN Wafers by Hydride Vapor Phase Epitaxy of Fe-Doped Thick GaN Layers Using GaAs Starting Substrates
Authors: Takemoto Kikurou , Kumagai Yoshinao , Murakami Hisashi , Koukitu Akinori
Published: December 2005

The hydride vapor phase epitaxy of a 400-µm-thick GaN layer doped with Fe was performed on a (111)A GaAs starting substrate covered by a NiTi protective layer on its back. By removing the GaAs substrate after GaN growth, a semi-insulating (SI) (0001) GaN wafer showing a resistivity of 8.8×1012 Ω cm at room temperature was successfully fabricated. A secondary ion mass spectrometry (SIMS) measurement revealed that doping with an Fe concentration of 1.5×1019 cm-3 was achieved. The full-width at half-maximum (FWHM) of X-ray diffraction (XRD) rocking curves of the (0002) and (1010) planes of GaN did not vary with Fe doping. The etch-pit density (EPD) of a SI GaN wafer was evaluated to be 8×106 cm-2.
Possible Breakthrough for Higher Tc Discovered in Bi(Pb)2223 Practical Tapes
Authors: Shimoyama Jun-ichi , Kato Takeshi , Kobayashi Shinichi , Yamazaki Kouhei , Hayashi Kazuhiko , Sato Ken-ichi
Published: December 2005

By systematic studies on the post-annealing effect in air for Bi(Pb)2223 practical tapes, T
c(onset) was found to be enhanced up to 115.2 K by annealing at 680°C for 250 h from 110.2 K for an as-synthesized tape. Annealing at ∼700°C for a long time always increased the T
c(onset) of the tape above 114 K, at which the generation of the Pb3221 phase simultaneously occurred during annealing. The slightly increased c-axis length was confirmed for annealed samples. The compositional change of cations in Bi(Pb)2223 during post-annealing is believed to be responsible for the T
c enhancement of the present system.
A Single Gap Transflective Display with Single Gamma Curve in the Fringe Field Switching Mode
Authors: Lim Young Jin , Jeong Yon Hak , Choi Min Oh , Jang Won Gun , Lee Seung Hee
Published: December 2005

The single-gap transflective liquid crystal display utilizing the fringe-field switching mode has a problem such that the voltage–dependent transmittance and reflectance curves do not match each other and thus a dual driving circuit is required. This study shows that the optimization of an angle of the electrode used in the transmissive and reflective area solves this problem so that the transflective display with a single gamma curve for reflective and transmissive region is possible.
Crystallographic and Luminescent Characteristics of Red-Emitting Ba2ZnS3:Mn Thin Film Electroluminescent Devices Prepared by Electron-Beam Evaporation
Authors: Ohmi Koutoku , Hara Katsuhiko , Yamasaki Michihiro , Ouchi Yukari , Kobayashi Hiroshi
Published: December 2005

The crystallographic and luminescent characteristics of Ba2ZnS3:Mn thin film electroluminescent (EL) devices have been investigated. Ba2ZnS3:Mn thin films have been prepared by electron-beam evaporation and postdeposition annealing at 600°C. It has been found that the suitable molar fraction of Ba/Zn in a deposition source pellet for suppressing impurity phases formed in thin films is about 1.8. The Ba2ZnS3:Mn EL devices show an efficient reddish-orange luminescence with the Commission Internationale de l'Eclairage (CIE) color coordinates of (x, y) = (0.60, 040). The luminance and efficiency at 1 kHz are 250 cd/m2 and 0.09 lm/W, respectively. Since the Ba2ZnS3:Mn thin films are crystallized even at 600°C, Ba2ZnS3:Mn is a promising red EL phosphor for a low-temperature process.