bluuebunny/crossref_metadata_2025 huggingface dataset:
Contrast Enhancement of ZEP520 Resist by Fullerene-Derivative Incorporation
Authors: Ishii Tetsuyoshi , Murata Yuka , Shigehara Kiyotaka
Published: October 2002

A fullerene-derivative nanocomposite resist system based on a positive-type electron-beam resist, ZEP520, is examined for contrast enhancement. The system containing 10 wt% of the derivative shows a substantially enhanced γ-value of 22.9, which is about three-and-a-half times higher than that of a virgin ZEP resist, and exhibits a very-high-contrast 50 nm pattern in an ultrathin film of 150 nm. Etching resistance is also enhanced and the derivative seems to be as effective as C60 in terms of the number of molecules incorporated. The contrast enhancement by fullerene-derivative incorporation has the potential to further improve the resolution of ZEP and will extend its application in nanolithography.
Flattening of Surface by Sputter-Etching with Low-Energy Ions
Authors: Takaomi Matsutani Takaomi Matsutani , Keigo Iwamoto Keigo Iwamoto , Takaharu Nagatomi Takaharu Nagatomi , Yoshihide Kimura Yoshihide Kimura , Yoshizo Takai Yoshizo Takai
Published: October 2002

The thickness of the damaged layer on a GaAs surface induced by a focused 25 kV Ga+ ion beam (FIB) was reduced from ∼24 nm to ∼2.6 nm by finishing with low-energy Ar+ ions of 200 eV, which has been evaluated by cross-sectional observation under a transmission electron microscope (TEM). The finishing rendered the surface of the damaged layer significantly flatter. This flattening was found to be sensitive to the ion energy; a very smooth flat surface is obtained by sputter-etching with 200 eV Ar+ ions, whilst sputter-etching with 100 eV Ar+ ions causes GaAs particles to remain in the FIB-induced damage layer on the surface, and thus it is not flat.
Material Design of GaN-Based Ferromagnetic Diluted Magnetic Semiconductors
Authors: Kazunori Sato Kazunori Sato , Hiroshi Katayama-Yoshida Hiroshi Katayama-Yoshida
Published: October 2002

Material design of GaN-based ferromagnetic diluted magnetic semiconductors is given based on ab initio calculations within the local spin density approximation. The electronic structure of 3d-transition-metal-atom-doped GaN was calculated by the Korringa-Kohn-Rostoker method combined with the coherent potential approximation. It was found that the ferromagnetic ground states were readily achievable in V-, Cr- or Mn-doped GaN without any additional carrier doping treatments. A simple explanation on the systematic behavior of the magnetic states in GaN-based diluted magnetic semiconductors is also given.
Frequency Agile Microstrip Patch Antenna Using Piezoelectric Substrates
Authors: Tae Song Joon , Hyun Cho Ik , Hoon Kim Young
Published: October 2002

An air-gap microstrip patch antenna using Pb(Zr,Ti)O3 (PZT) post and a microstrip patch antenna using LiNbO3
substrate were fabricated. It is suggested that the operating frequency of the microstrip patch antenna can be controlled by an electric field using piezoelectric material as its substrate. The frequency shift versus the electric field were 1.90 MHz-cm/kV with DC bias, 6.12 MHz-cm/kV with AC bias at the air-gap microstrip patch antenna and 5.57 MHz-cm/kV with DC bias at the LiNbO3 microstrip patch antenna.
Hysteretic Current–Voltage Characteristics of All-Oxide (LaSr) MnO3/BaTiO3/(LaSr) TiO3pin-Diode
Authors: Nakasaka Takuya , Urago Kazuyuki , Sugiura Masanori , Kobayashi Takeshi
Published: October 2002

All-oxide pin-diodes with the ferroelectric BaTiO3
i-layer were prepared on (100) Nb-doped SrTiO3 substrates by the pulsed laser deposition method and ion mesa-etching. The p- and n-layers, respectively, consisted of (LaSr)MnO3 and (LaSr)TiO3. The current–voltage (I–V) curves exhibited the built-in voltage of about 0.3 V and the reverse leakage current was about -1 µA at the voltage of -8 V. Due to the ferroelectricity of BaTiO3, the I–V curves revealed the hysteretic characteristics even when the electron was injected into the conduction band of the BaTiO3 layer, suggesting that the remanent polarization inside the BaTiO3
i-layer is not eliminated even under the coexistence of the excess carriers (electrons) injected.
Temperature-Insensitive Intersubband-Transitions in InGaAs/AlAsSb Multiple Quantum Well Designed for Optical Communication Wavelength*
Authors: Neogi Arup , Yoshida Haruhiko , Mozume Teruo , Georgiev Nikholai , Wada Osamu
Published: October 2002

We present the first experimental evidence on temperature independent intersubband transitions in InGaAs/AlAs/AlAsSb/InP quantum well (QW) structures tailored for optical communication at 1.55 µm. The relative strength and peak wavelengths of intersubband transitions between the four levels in the coupled double QW's change with temperature, due to the carrier redistribution between the miniband states in the conduction band. The temperature insensitivity is observed for the conduction subband electronic transitions between the ground and the uppermost confined subband states in asymmetrically coupled double QW. The temperature dependence of intersubband transitions in coupled and uncoupled systems has been compared and the coupled QW's has been observed to exhibit an extremely small intersubband-transition temperature gradient of 2.3×10-3 meV/K compared to 0.155 meV/K in uncoupled QW's.
Synthesis of Boron Nitride Films by Microwave Plasma Chemical Vapor Deposition in Fluorine-Containing Gases
Authors: Matsumoto Seiichiro , Zhang Wenjun
Published: October 2002

Boron nitride films were deposited on (001) silicon substrates by rf-or dc-bias-assisted microwave plasma chemical vapor deposition in a He–N2–BF3–H2 gas system. Scanning electron microscopy, X-ray diffraction, and infrared and Raman spectroscopies were performed to characterize the films. The deposited films were composed of cubic boron nitride (cBN) and turbostratic and hexagonal boron nitrides with the cubic phase in the range of 50 to 70%. Raman measurements showed both transverse optical (TO) and longitudinal optical (LO) characteristic peaks of cBN. Although these peaks are very broad, this is believed to be the first reliable report on the appearance of clear Raman signals of cBN deposited by microwave plasma chemical vapor deposition.
Homoepitaxial Growth of Diamond Single-Phase Thin Films by Pulsed Laser Ablation of Graphite
Authors: Yoshitake Tsuyoshi , Nishiyama Takashi , Nagayama Kunihito
Published: October 2002

Diamond thin films were grown on diamond (100) substrates in oxygen atmospheres by pulsed laser deposition (PLD) using an ArF excimer laser. The optimum oxygen atmosphere of 5×10-2 Torr can etch the sp2 bonding fractions preferentially. At substrate temperatures between 550°C and 600°C, single-phase diamond films consisting of diamond crystal with diameters of 1–5 µm could be grown. The results demonstrated that the diamond thin films can be homo-grown using PLD by the optimization of the deposition parameters such as the oxygen pressure and the substrate temperature.
Combinatorial Technique Applied to the Synthesis of Carbon Nanotubes
Authors: Hwang Sun-Kyu , Lee Ki-Do , Lee Kun-Hong
Published: October 2002

A combinatorial technique was used to determine the optimum catalyst combination for the efficient synthesis of carbon nanotubes (CNTs). The morphology, length and yield of CNTs greatly differ depending on the catalyst combinations. Among 20 different compositions of mixed catalysts, CNTs of good structure were obtained when the volume ratios of the three precursor solutions–Co(NO3)2, Ni(NO3)2 and Fe(NO3)3–were 4:2:4 (island #7) and 1:5:4 (island #18).
Fully Quantum-Mechanical Calculation of Gate Tunneling Current in Ultrathin Silicon-on-Insulator Metal-Oxide-Semiconductor Devices
Authors: Iwata Hideyuki
Published: October 2002

The gate leakage currents due to direct tunneling in silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) have been investigated for various SOI layer thicknesses (t
SOI) using fully quantum-mechanical calculation. As t
SOI is reduced to 4 nm under the full-depletion condition, the gate tunneling current in SOI MOSFETs increases and becomes higher than that in bulk MOSFETs. However, considering the power supply voltage of SOI MOSFETs is lower than that of bulk MOSFETs, the increase is not so large as to become a serious problem. As t
SOI further decreases, the tunneling current decreases and then increases considerably for t
SOI below 2 nm. Such quantum-mechanical effects on the tunneling current in SOI MOSFETs are discussed in detail.
Temperature Characteristics of 1.5-µm-Band MgO Doped LiNbO3 Quasi-Phase Matched Wavelength Converters
Authors: Bo Chen Bo Chen , Chang-Qing Xu Chang-Qing Xu , Bing Zhou Bing Zhou , Yasukazu Nihei Yasukazu Nihei , Akinori Harada Akinori Harada , Yong Wang Yong Wang
Published: October 2002

Temperature characteristics of MgO doped LiNbO3 quasi-phase matched (QPM) wavelength converters are studied based on different frequency generation (DFG) for the first time. The temperature sensitivity of the QPM wavelength is found to be about 0.113 nm/°C for the device with a period of 18.7 µm, while the wavelength conversion efficiency at a pump power of -0.5 dBm is found to be -26 dB. These values are compatible with the best values for non-doped LiNbO3 QPM-DFG wavelength converters reported to date. It is shown that the converted wavelength can be tuned by changing device operation temperature and pump wavelength, indicating the capability of variable-in variable-out wavelength conversions required in optical cross connect networks.
Irregular Resistance Change in Thin Ag Film on Si Substrate
Authors: Iida Shoji , Hiraoka Akihiko , Tai Toshiaki , Noritake Hideaki
Published: October 2002

We measured the change in crystallization and resistance of Ag film during deposition onto Si(100) or Si(111) substrates. For the Ag crystallization structure on Si(100), it was difficult to specify the type, but in the case of Si(111), the crystallization was √3×√3. Resistance change was irregular with increasing Ag film thickness for both Si(100) and Si(111) substrates. This irregularly can be explained by the partial occupied state formation due to Si–Ag electron coupling and by the quantum dot formation in the Ag island having a subband energy structure.
Measurements of Cell Thickness Distributions in Reflective Liquid Crystal Cells Using a Two-Dimensional Stokes Parameter Method
Authors: Marenori Kawamura Marenori Kawamura , Susumu Sato Susumu Sato
Published: October 2002

A two-dimensional (2D) Stokes parameter method for measuring the cell properties of reflective liquid crystal (LC) cells is proposed. Relationships between the Stokes parameters of the reflected light from the reflective LC cell and the thickness of the LC layer are given by Jones matrix representation. The hyperfine cell thickness distributions can be determined by measuring Stokes parameters of the LC cell and solving Stokes parameter equations. Moreover, these values are discussed and compared with those of the transmissive-type LC cell.
Visibility Measurement with an X-Ray Interferometer Using a Coincidence Technique
Authors: Makina Yabashi Makina Yabashi , Kenji Tamasaku Kenji Tamasaku , Tetsuya Ishikawa Tetsuya Ishikawa
Published: October 2002

A coincidence measurement was combined with conventional interferometry in the X-ray region. It was theoretically and experimentally shown that the coincidence counting rate between two output ports of an X-ray interferometer is directly related to the visibilities of the interference beams. The method developed here will be a powerful tool in constructing more general X-ray interferometers.
Materials Design of Transparent and Half-Metallic Ferromagnets in V- or Cr-Doped ZnS, ZnSe and ZnTe without P- or N-type Doping Treatment
Authors: Katayama-Yoshida Kazunori Sato
Published: October 2002

We propose materials design to fabricate the transparent and half-metallic ferromagnets in V or Cr-doped ZnS, ZnSe and ZnTe based upon ab initio electronic structure calculation with the local-spin-density-functional approximation. The electronic structure and the magnetic properties of 3d-transition-metal-atom-doped II-VI compound semiconductors of ZnS, ZnSe and ZnTe are systematically calculated using the Korringa-Kohn-Rostoker method with taking into account the substitutional disorder by the coherent potential approximation. It is shown that V or Cr-doped ZnS, ZnSe and ZnTe are ferromagnetic without p- or n-type doping treatment, however, Mn-, Fe-, Co- or Ni-doped ZnS, ZnSe and ZnTe are the spin-glass states.
Influence of Interface Structure on Oxidation Rate of Silicon
Authors: Takahashi Kensuke , Nohira Hiroshi , Nakamura Tomohiro , Ohmi Tadahiro , Hattori Takeo
Published: October 2002

X-ray photoelectron spectroscopy studies on the changes in SiO2/Si(111) interface structures and oxidation rates of Si(111) with the progress of oxidation were performed for oxide films formed using atomic oxygen at 400°C. The following results are obtained for the same oxidation condition: 1) an atomically uniform oxidation reaction occurs at the SiO2/Si interface, 2) the oxidation rate changes periodically with the progress of oxidation and decreases significantly at specific interface structures. Therefore, it is revealed that the oxidation rate of Si is influenced by the SiO2/Si interface structure.
Metal-Insulator Transition in Stable One-Dimensional Arrangements of Single Gold Atoms
Authors: Kizuka Tokushi , Umehara Shinjiro , Fujisawa Satoru
Published: October 2002

The atomic arrangement and conductance during the separation process of gold point contacts were simultaneously observedin situby high-resolution transmission electron microscopy. One-dimensional arrangements of gold single atoms, i.e., atomic wires, appeared between two tips at the point contacts. They were stable when their length was increased up to 2.6 nm. The interatomic distance of the wires was 0.25–0.31 nm. It was found that metal-insulator transition occurs in the wires.
Memory Operation of Silicon Quantum-Dot Floating-Gate Metal-Oxide-Semiconductor Field-Effect Transistors
Authors: Kohno Atsushi , Murakami Hideki , Ikeda Mitsuhisa , Miyazaki Seiichi , Hirose Masataka
Published: October 2002

The drain current versus gate voltage characteristics of metal-oxide-semiconductor field-effect transistors (MOSFETs) with a silicon quantum-dot (QD) layer floating gate have shown the unique hysteresis and current bumps which arise from the electron charging or discharging of the QDs with an average dot height of 5 nm. The drain current response to application of a single-pulse gate bias has revealed that the multiple-step charging of the QD layer occurs until single electron occupation at each QD is achieved.
Reduction of Base-Collector Capacitance in Submicron InP/GaInAs Heterojunction Bipolar Transistors with Buried Tungsten Wires
Authors: Toshiki Arai Toshiki Arai , Shigeharu Yamagami Shigeharu Yamagami , Yasuyuki Miyamoto Yasuyuki Miyamoto , Kazuhito Furuya Kazuhito Furuya
Published: October 2002

A buried metal heterojunction bipolar transistor with a 0.5-µm-wide emitter was fabricated by electron-beam lithography, in which three tungsten wires of 100 nm width, 100 nm height and 200 nm period were buried in the InP collector layer. For the device with an emitter area of 0.5×2.5 µm2, total base-collector capacitance was reduced to about 30% of that calculated from the physical dimensions of a conventional heterojunction bipolar transistor, and a current gain cutoff frequency of 86 GHz and a maximum oscillation frequency higher than 135 GHz were obtained.
Generation of Pretilt Angle for Nematic Liquid Crystal Using the Photodimerization Method on Various New Photo-Crosslinkable Polyimide Based Polymers
Authors: Hwang Jeoung-Yeon , Seo Dae-Shik , Son Jong-Ho , Suh Dong Hack
Published: October 2002

We synthesized the various new photo-crosslinkable polyimide based polymers and generation of pretilt angle for a nematic liquid crystal (NLC) using a photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimatric analysis (TGA) measurement until 450°C. The NLC pretilt angle generated was about 2.5°–3.0° by polarized UV exposure on the photopolymers containing a biphenyl (BP), decyl (De), and cholesteryl(chol), chalcone(Chal) group, respectively. However, low pretilt angle of the NLC was measured by polarized UV exposure on the photopolymers containing the fluorine and chalcone group. The NLC pretilt angle generated is attributed to the biphenyl and alkyl moieties, and the photo-dimerized chalcone group of the photopolymer.
Effect of Mo Addition on the Formation of Metastable fcc Zr2Ni and Icosahedral Phases in Zr–Al–Ni–Cu Glassy Alloy
Authors: Saida Junji , Inoue Akihisa
Published: October 2002

We investigated the transformation behavior at the initial crystallization stage in the Zr–Al–Ni–Cu–Mo glassy alloy. In the Zr65Al7.5Ni10Cu12.5Mo5alloy, the crystallization reaction changes to two reactions and the first reaction corresponds to the nanoscale fcc Zr2Ni phase formation. The two-stage crystallization reaction is also observed in the Zr65Al7.5Ni5Cu17.5Mo5alloy, where the primary phase is the nanoscale icosahedral quasicrystalline phase. The difference in the primary phase between the two alloys is attributed to the difference in the chemical affinities of Mo with Cu and Ni. The formation of nanoscale icosahedral and fcc Zr2Ni phases leads to the hypothesis that the icosahedral short-range order exists in the glassy state of the Zr–Al–Ni–Cu alloy as a unit structure in both phases.
Scanning Tunneling Microscopy/Spectroscopy Study of Point Defects on TiO2(110)-(1×1) Surface
Authors: Sakai Yoshiyuki , Ehara Shaw
Published: October 2002

The electronic structure around a point defect in an annealed TiO2(110)-(1×1) surface has been studied by scanning tunneling microscopy/spectroscopy. At a defect site of bridging oxygen, we found an unoccupied defect state at 1.2 eV above the Fermi level. Trapped electrons at the gap states were found on fivefold-coordinated titanium ion rows by current imaging tunneling spectroscopy. We calculated the electronic states of an oxygen defect by the spin-polarized discrete variational (DV)-X α method using a cluster model. The calculated defect states are in good agreement with the experimental results.
High-Efficiency Neutral-Beam Generation by Combination of Inductively Coupled Plasma and Parallel Plate DC Bias
Authors: Samukawa Seiji , Sakamoto Keisuke , Ichiki Katsunori
Published: October 2002

To avoid several kinds of radiation damage caused by charge build-up and by ultraviolet and X-ray photons during etching processes, we have developed a high-performance, neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and top and bottom carbon parallel plates. The bottom carbon plate includes numerous apertures for extracting neutral beams from the plasma. By supplying a direct current (DC) bias to the top plate, the generated ions are accelerated towards the bottom plate. Most of them are efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during the ion transport and with aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. When the aperture diameter and aperture length were 1 mm and 10 mm, respectively, the neutralization efficiency was almost 100% and the neutral flux density was equivalent to 1.2–2.8 mA/cm2. A neutral beam could thus be produced efficiently from the ICP source and the apertures in the bottom plate.
Properties of HfO2/Hf-Silicate/Si Structures with Hf-Silicate Formed by Hf Metal Deposition and Subsequent Reaction
Authors: Bae Geunhag , Lee Hunjung , Jung Donggeun , Kang Hyeoksu , Roh Yonghan , Yang Cheol-Woong
Published: October 2002

Properties of the HfO2/Hf-silicate/Si structure with the Hf-silicate layer which was formed by Hf metal deposition on Si and subsequent reaction of Hf with Si and oxygen during the HfO2 deposition were studied. Post-deposition N2 annealing reduced the equivalent oxide thickness (EOT) value and improved leakage characteristics of the HfO2/Hf-silicate/Si structure. The EOT value was reduced from 2.70 nm to 2.23 nm after annealing. At a proper voltage of 2.5 V, which was defined as the difference between the applied gate bias and the flat band voltage, the leakage current density of annealed HfO2/Hf-silicate/Si structure was 1.88×10-7 A/cm2 while that of as-formed HfO2/Hf-silicate/Si structure was 1.92×10-6 A/cm2. The breakdown field increased from 7.29 MV/cm to 9.71 MV/cm after annealing.
Stabilization of Deoxyribonucleic Acid Network on Mica Surface Using Post Ethanol Treatment
Authors: Nakayama Yoshitaka , Tanaka Hiroyuki , Kawai Tomoji
Published: October 2002

Recently we have successfully fabricated large-scale deoxyribonucleic acid (DNA) networks on mica surfaces. However there is a problem that DNA networks are eliminated instantly when soaked in water. We have successfully found that DNA networks pretreated with ethanol are not eliminated even after being soaked in water. The method of treating DNA networks with ethanol was very simple. The sample is soaked in ethanol for 10 seconds followed by blowing off the remaining liquid with air. This paper provides relatively simple stabilization methods for large-scale DNA networks on mica surfaces that are suitable for the practical application of DNA networks as biomaterials for medical engineering and environment purposes such as capturing intercalating toxic pollutants solved in water solution.
Effect of Oxygen Coverage on Electron Emission from Boron-Doped Polycrystalline Diamond
Authors: Yamada Takatoshi , Kanda Ken-ichi , Okano Ken , Sawabe Atsuhito
Published: October 2002

The relationship between the electron emission properties of a boron-doped chemical vapor deposited polycrystalline diamond thin film and the oxygen coverage on the diamond surface is systematically investigated. The threshold voltage of electron emission becomes higher with increasing oxygen coverage on the surface. The change of emission barrier height estimated from the slopes of Fowler-Nordheim plots and from the coverage of adsorbed oxygen atoms is evaluated. From the results, it was speculated that the emission barrier height was changed by the surface dipole layer that was formed by oxygen atoms on the diamond surface and led to the changes in the electron emission properties.
A New Optics for Dark-Field Imaging in X-Ray Region `Owl'
Authors: Ando Masami , Sugiyama Hiroshi , Maksimenko Anton , Pattanasiriwisawa Wanwisa , Hyodo Kazuyuki , Zhang Zhang , Xiaowei Xiaowei
Published: October 2002

An X-ray optics for X-ray dark-field imaging named `Owl' is proposed. It involves an asymmetric monochromator and a monolithic X-ray optics comprising a collimator C and an analyzer A. The C and A have 4,4,0 diffraction and thickness of 1.08 mm±10 µm. The X-ray energy used was 35 keV. These diffractions have an angular width of approximately 0.3 µrad. The analyzer A accepts only the refracted component from a sample S which is located between C and A, while eliminating the straight component without reacting with it. Two samples, one Al matrix containing boron fibers of 300 µm diameter and the other a wax block containing a nylon fiber simulating breast cancer, show very clear fiber imaging usually not visible by the conventional X-ray technique.
GaN-Based Light Emitting Diodes with Tunnel Junctions
Authors: Takeuchi Tetsuya , Hasnain Ghulam , Corzine Scott , Hueschen Mark , Jr. Richard P. Schneider, , Kocot Chris , Blomqvist Mats , Chang Ying-lan , Lefforge Dale , Krames Mike R. , Cook Lou W. , Stockman Steve A.
Published: October 2002

We have demonstrated hole injection through a tunnel junction embedded in the GaN-based light emitting diode structure. The tunnel junction consists of 30 nm GaN:Si++ and 15 nm InGaN:Mg++ grown on a GaN–InGaN quantum well heterostructure. The forward voltage of the light emitting diode, including the voltage drop across the reverse-biased tunnel junction, is 4.1 V at 50 A/cm2, while that of a standard light emitting diode with a conventional contact structure is 3.5 V. The light output of the diode with the tunnel junction is comparable to that of the standard device. This tunnel junction eliminates the need for a highly resistive p-AlGaN cladding layer in short-wavelength laser diodes and the semi-transparent electrode required for current spreading in conventional GaN-based light emitting diodes.
Image Contrast of Lattice Defects in X-Ray Topography by Resonant Scattering
Authors: Riichirou Negishi Riichirou Negishi , Masami Yoshizawa Masami Yoshizawa , Shengming Zhou Shengming Zhou , Isao Matsumoto Isao Matsumoto , Tomoe Fukamachi Tomoe Fukamachi , Takaaki Kawamura Takaaki Kawamura
Published: October 2002

In order to observe the effect of atomic resonant scattering on X-ray topography, topographs of a GaAs crystal with the 200 reflection have been taken using synchrotron X-rays with energy near the K-absorption edges of Ga and As. The X-ray energy has been tuned to four typical resonant scattering conditions. It is shown that the contrast of lattice defects observed in topographs changes with the resonant scattering conditions. Such topography taken under resonant scattering is useful for studying lattice defects in crystals.
Planarization of the YBa2Cu3O7-x Base Electrodes in Trilayer Josephson Junctions
Authors: Michitaka Maruyama Michitaka Maruyama , Toshiki Furutani Toshiki Furutani , Yasuyuki Yoshinaga Yasuyuki Yoshinaga , Takayasu Kito Takayasu Kito , Gen-ichiro Matsuda Gen-ichiro Matsuda , Hiroyuki Akaike Hiroyuki Akaike , Masumi Inoue Masumi Inoue , Akira Fujimaki Akira Fujimaki , Hisao Hayakawa Hisao Hayakawa
Published: October 2002

We have applied the chemical-mechanical polishing (CMP) planarization technique to YBa2Cu3O7-x
(YBCO) films for the base electrodes in trilayer Josephson junctions. In our planarization process, YBCO films were directly polished using a diamond-based slurry and cleaned by low-angle ion etching. The planarized films showed extremely flat surfaces with the average roughness (R
a) less than 0.5 nm. Moreover, the c-axis-oriented YBCO/PrBa2Cu3O7-y
(PBCO)/YBCO trilayer junctions fabricated using the planarized films as the base electrodes showed resistively shunted junction-like characteristics even when the PBCO barriers were as thin as 10 nm. The I
c
R
n products of the junctions were more than 1 mV at 4.2 K. Our results indicate that CMP is an effective method for obtaining flat YBCO films and for improving the properties of trilayer Josephson junctions.
Thin-Film Vertical-Cavity Surface-Emitting Lasers Containing Strained InGaAs Quantum Wells Fabricated by Substrate Removal
Authors: Ouchi Toshihiko , Sato Takahiro , Sakata Hajime
Published: October 2002

We have demonstrated 980-nm thin-film vertical-cavity surface-emitting lasers (VCSELs), which have strained InGaAs quantum wells in the active region, for the hybrid integration of optoelectronic devices. The thin-film VCSELs were fabricated using a functional layer transfer technique, which consisted of pre-fabrication of the laser structure, Au–Sn metal-bonding onto an AlN substrate and subsequent removal of the growth substrate. Threshold currents of 3.3 mA, output powers of over 3 mW and a threshold voltage of 2.1 V were obtained, indicating there was no serious degradation of laser characteristics due to the transfer process.
Effect of an Occluding Contour on the Volume Perception in Binocular Stereopsis
Authors: Osamu Watanabe Osamu Watanabe , Masanori Idesawa Masanori Idesawa
Published: October 2002

When we observe a solid object such as a sphere or a cylinder, we cannot “see” its rear part. However, we often “perceive” the rear part of an object with a sense of solidity. This perception is called the volume perception. In the present research, we investigated the volume perception in stereopsis psychophysically. The results suggest that the cue for the volume perception is a type of occluding contour, that is, the volume perception occurs when a contour is generated by self-occlusion such as the outline of a sphere, while the rear part is not perceived when a contour corresponds to a discontinuous ridge such as an edge of a polyhedron.
High-Temperature Electrical Properties of NiO-Doped WO3 Thick Films
Authors: Park Jinseong , Hong Kwangjun , Lee Woosun , Shin Yongjin
Published: October 2002

The electrical properties of NiO-doped WO3 thick films were investigated as a function of the amount of NiO, partial pressure of oxygen, temperature and NO2 concentration. NiO-doped WO3 thick films were prepared by the screen-printing technique. The grain growth is inhibited by the addition of NiO. The electrical conductance of undoped WO3 is high at a low partial pressure of oxygen. The electrical conductance of NiO-doped WO3 increases with NiO content of up to 1.0 mol%, and then decreases. The sensitivity for NO2 gas increased up to 1.0 mol% of NiO, and then decreased.
Current Paths over Grain Boundaries in Polycrystalline Silicon Films
Authors: Kimura Mutsumi , Inoue Satoshi , Shimoda Tatsuya , Sameshima Toshiyuki
Published: October 2002

Current paths over grain boundaries in polycrystalline silicon films have been analyzed using two-dimensional simulations. It is found that the current path is winding and longer than the distance between the electrodes. It is also found that the current path tends to flow perpendicular to the grain boundary and avoids the vertex of the grains. The reason why the current path tends to flow perpendicular to the grain boundary can also be explained using an analytical method.
Enhancement of Second-Harmonic Generation in Helical Ferroelectric Liquid-Crystal Cells under Oblique Incidence
Authors: Hoshi Hajime , Shin Ki-Chul , Chung Doo-Han , Ishikawa Ken , Takezoe Hideo
Published: October 2002

A numerical method was introduced to study the second-harmonic generation (SHG) in helical ferroelectric liquid crystals. The level of approximation is the same as that of the 4×4 matrix method and any polarization conditions can be analyzed. A special phase matching of the SHG, which occurs when the fundamental and SH waves are located near the photonic band edges, was analyzed under the oblique incidence condition. For the material used in previous studies, numerical results showed some features at an incidence angle of 30°. (1) Enhanced SHG is possible when the wavelength of SHG matches the dips near the edges of the total-reflection half-pitch band in the linear reflection spectra. (2) The SH peak intensity is expected to show d
3 dependence of cell thickness d.
Influence of the Surface Alignment Conditions and the Polymer Stabilization on the Electrooptic Characteristics of Ferroelectric Liquid Crystal Displays Exhibiting Half-V Switching -A Comparison of Photoalignment and Rubbing Technique-
Authors: Tetsuji Ishitani Tetsuji Ishitani , Hirokazu Furuta Hirokazu Furuta , Jun Xu Jun Xu , Shunsuke Kobayashi Shunsuke Kobayashi
Published: October 2002

In this paper, it is reported that the electrooptic (EO) performance of a ferroelectric liquid crystal display (FLCD) exhibiting half-V-shaped switching using an FLC material which has no smectic A phase-R2301 (Clariant Japan) depends on the surface alignment conditions such as photoalignment and rubbing. It is shown that an FLCD cell fabricated using the photoalignment technique, which produces weak azimuthal anchoring, results in a superior EO performance at a low saturation operation voltage and for a wide cone (deflection) angle compared to those fabricated under a weak-rubbing condition. Furthermore, polymer stabilization using newly developed photocurable monomers was adopted in order to increase the thermal stability of the EO characteristics of a half-V-shaped FLCD. This polymer stabilization is also shown to influence the EO characteristics.
The Effect of an Electrostatic Force on Imaging a Surface Topography by Noncontact Atomic Force Microscope
Authors: Tadashi Shiota Tadashi Shiota , Keiji Nakayama Keiji Nakayama
Published: October 2002

Noncontact atomic force microscope (NC-AFM) with and without scanning Kelvin probe force microscope (SKPM) has been studied to clarify the effect of an electrostatic force between a cantilever tip and a specimen on the NC-AFM imaging. The NC-AFM image contrast of a quenched Si (111) surface reflected the distribution of the surface potential, while that observed with a feedback of the SKPM signal showed good agreements with the previous results. The experimental results show that the electrostatic force affects the NC-AFM image formation, so that the electrostatic effect must be compensated to obtain an actual surface topography by NC-AFM.
Neutron Evolution from a Palladium Electrode by Alternate Absorption Treatment of Deuterium and Hydrogen
Authors: Mizuno Tadahiko , Akimoto Tadashi , Ohmori Tadayoshi , Takahashi Akito , Yamada Hiroshi , Numata Hiroo
Published: October 2002

We observed neutron emissions from palladium after it absorbed deuterium from heavy water followed by hydrogen from light water. The neutron count, the duration of the release and the time of the release after electrolysis was initiated all fluctuated considerably. Neutron emissions were observed in five out of ten test cases. In all previous experiments reported, only heavy water was used, and light water was absorbed only in accidental contamination. Compared to these deuterium results, the neutron count is orders of magnitude higher, and reproducibility is much improved.
Electron Ionization, Attachment and Detachment Coefficients in SF6and N2Gas Mixtures
Authors: Li Xu-Guang , Xiao Deng-Ming , Yang Shao-Jun
Published: October 2002

In this paper, we present an analysis of the avalanche growth in electronegative gases which exhibit detachment process in addition to ionization and attachment. The model is used to determine swarm parameters from a pulsed Townsend method. As an example, the swarm parameters for SF6–N2are presented and discussed. A new swarm method for measurement of electron ionization, attachment and detachment from negative ions in SF6and its mixtures was developed. The value of transport coefficient of SF6–N2has been given.
Adsorption of Fluorinated C60on the Si(111)-(7×7) Surface Studied by Scanning Tunneling Microscopy and High-Resolution Electron Energy Loss Spectroscopy
Authors: Fujikawa Yasunori , Sadowski Jerzy T. , Kelly Kevin F. , Nakayama Koji S. , Mickelson Edward T. , Hauge Robert H. , Margrave John L. , Sakurai Toshio
Published: October 2002

The adsorption structure of fluorinated C60molecules deposited on the Si(111)-(7×7) surface was studied using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). The results of HREELS revealed the existence of the silicon-fluorine vibration modes with the energy of 103–107 meV, indicating that some of the fluorine atoms were detached from the molecules and chemisorbed to the surface. These fluorine adsorption sites were observed around the adsorbed molecules directly in the STM images. Many of the fluorine-adsorbed sites were found to form thread-like structures. Random formation of the F–Si bonds on the surface prohibits the fluorinated fullerene's freedom from forming an ordered monolayer on the Si(111)-(7×7) surface.
Theoretical Analysis of Tip Effect on Noncontact Atomic Force Microscopy Image of Si(100) 2×1: H Surface
Authors: Miura Nariaki , Tsukada Masaru
Published: October 2002

The influence of the tip structure on the noncontact atomic force microscopy (nc-AFM) image of a hydrogenated Si(100) 2×1 surface is revealed by a theoretical simulation with the first-principles density functional approach. Two different Si tips, i.e., a clean Si(111) tip and a hydrogen terminated Si(111) tip, are modeled by SiH3and SiH4clusters, respectively, and the simulated nc-AFM images are compared for the respective tip models. The clean Si tip produced a much larger corrugation amplitude than the hydrogen-terminated Si tip. For the latter tip, a marked change in the image is observed with the approach of the tip turning point towards the surface. When the tip turning point becomes very close to the surface, the inversion of the brightness of the image is found to appear.
Comparison of Material Properties of CuInSe2Films Produced by Reaction of Metallic Alloys to H2Se/Ar and Elemental Se Vapour
Authors: Alberts V.
Published: October 2002

In this study, CuInSe2thin films were produced by the reaction of identical precursors toelemental Se vapour and H2Se/Ar gas. In order to compare the respective growth processes, the reaction temperature was varied between 300°C and 600°C, while all other parameters were kept constant. For a given set of experimental parameters, significant differences were observed in terms of crystalline quality and in-depth compositional uniformity. At low selenization temperatures below 400°C, the reaction process was incomplete, irrespective of the selenization process considered. Reaction of precursors to H2Se/Ar at temperatures above 400°C (for 40 min), produced fully reacted films with uniform and dense surface morphologies and a high degree of in-depth compositional uniformity. Under similar conditions, Se vapour treated samples had nonuniform surface morphologies with an associated relatively large variation in the Cu/In atomic ratio and Se concentration through the depth of the samples. This comparative study identifies the important differences between the two reactive processes and the advantages in using H2Se/Ar as a chalcogenide source.
Theories of Gamma-Ray Bursts
Authors: Mészáros P.
Published: October 2002

▪ Abstract  The gamma ray burst phenomenon is reviewed from a theoretical point of view, with emphasis on the fireball shock scenario of the prompt emission and the longer wavelength afterglow. Recent progress and issues are discussed, including spectral-temporal evolution, localizations, jets, spectral lines, environmental and cosmological aspects, as well as some prospects for future experiments in both electromagnetic and nonelectromagnetic channels.
USE OF MULTILINE CULTIVARS AND CULTIVAR MIXTURES FOR DISEASE MANAGEMENT
Authors: Mundt C. C.
Published: October 2002

▪ Abstract  The usefulness of mixtures (multiline cultivars and cultivar mixtures) for disease management has been well demonstrated for rusts and powdery mildews of small grain crops. Such mixtures are more useful under some epidemiological conditions than under others, and experimental methodology, especially problems of scale, may be crucial in evaluating the potential efficacy of mixtures on disease. There are now examples of mixtures providing both low and high degrees of disease control for a wide range of pathosystems, including crops with large plants, and pathogens that demonstrate low host specificity, or are splash dispersed, soilborne, or insect vectored. Though most analyses of pathogen evolution in mixtures consider static costs of virulence to be the main mechanism countering selection for pathogen complexity, many other potential mechanisms need to be investigated. Agronomic and marketing considerations must be carefully evaluated when implementing mixture approaches to crop management. Practical difficulties associated with mixtures have often been overestimated, however, and mixtures will likely play an increasingly important role as we develop more sustainable agricultural systems.
STRIPERUST OFWHEAT ANDBARLEY INNORTHAMERICA: A Retrospective Historical Review
Authors: Line Roland F.
Published: October 2002

▪ Abstract  This retrospective review deals with the sequence of events and research progress on control of stripe rust of wheat and barley in North America. From the discovery of stripe rust in 1915, it documents the early years of stripe rust research, the 20-year hiatus when stripe rust was not considered important and research was almost nonexistent, the short period in the 1950s when stripe rust became prevalent in the central United States, and the severe epidemics in the West in the 1960s and the associated revival and expansion of research. Finally, it covers 1968 to 2001 when the earlier information was consolidated and combined with results of new research to enable prediction and control of stripe rust, especially in the West.
MOLECULAR BASIS OF RECOGNITION BETWEEN PHYTOPHTHORA PATHOGENS AND THEIR HOSTS
Authors: Tyler Brett M.
Published: October 2002

▪ Abstract  Recognition is the earliest step in any direct plant-microbe interaction. Recognition between Phytophthora pathogens, which are oomycetes, phylogenetically distinct from fungi, has been studied at two levels. Recognition of the host by the pathogen has focused on recognition of chemical, electrical, and physical features of plant roots by zoospores. Both host-specific factors such as isoflavones, and host-nonspecific factors such as amino acids, calcium, and electrical fields, influence zoospore taxis, encystment, cyst germination, and hyphal chemotropism in guiding the pathogen to potential infection sites. Recognition of the pathogen by the host defense machinery has been analyzed using biochemical and genetic approaches. Biochemical approaches have identified chemical elicitors of host defense responses, and in some cases, their cognate receptors from the host. Some elicitors, such as glucans and fatty acids, have broad host ranges, whereas others such as elicitins have narrow host ranges. Most elicitors identified appear to contribute primarily to basic or nonhost resistance. Genetic analysis has identified host resistance (R) genes and pathogen avirulence (Avr) genes that interact in a gene-for-gene manner. One Phytophthora Avr gene, Avr1b from P. sojae, has been cloned and characterized. It encodes a secreted elicitor that triggers a system-wide defense response in soybean plants carrying the cognate R gene, Rps1b.
Resistance to Neointimal Hyperplasia and Fatty Streak Formation in Mice With Adrenomedullin Overexpression
Authors: Imai Yasushi , Shindo Takayuki , Maemura Koji , Sata Masataka , Saito Yuichiro , Kurihara Yukiko , Akishita Masahiro , Osuga Junichi , Ishibashi Shun , Tobe Kazuyuki , Morita Hiroyuki , Oh-hashi Yoshio , Suzuki Toru , Maekawa Hiromitsu , Kangawa Kenji , Minamino Naoto , Yazaki Yoshio , Nagai Ryozo , Kurihara Hiroki
Published: October 2002

Objective—

Several in vitro studies have implicated that adrenomedullin (AM) plays an important role in the pathogenesis of vascular injury and fatty streak formation. To test this possibility in vivo, we evaluated 2 experimental models using transgenic mice overexpressing AM in a vessel-selective manner (AMTg mice).

Methods and Results—

Placement of a periarterial cuff on femoral arteries resulted in neointimal formation at 2 to 4 weeks to a lesser extent in AMTg mice than in their wild-type littermates (at 28 days, intima/media area ratio 0.45±0.14 versus 1.31±0.41, respectively;
P
<0.001). This vasculoprotective effect observed in AMTg mice was inhibited by

N
ω

-nitro-
l
-arginine methyl ester. We further examined the effect of AM on hypercholesterolemia-induced fatty streak formation by crossing AMTg mice with apolipoprotein E knockout mice (ApoEKO mice). The extent of the formation of fatty streak lesions was significantly less in ApoEKO/AMTg mice than in ApoEKO mice (percent lesion area 12.0±3.9% versus 15.8±2.8%, respectively;
P
<0.05). Moreover, endothelium-dependent vasodilatation as indicative of NO production was superior in AMTg/ApoEKO mice compared with ApoEKO mice.

Conclusions—

Taken together, our data demonstrated that AM possesses a vasculoprotective effect in vivo, which is at least partially mediated by NO.
cAMP Signal Transduction, A Potential Compensatory Pathway for Coronary Endothelial NO Production After Heart Failure
Authors: Zhang Xiao-Ping , Tada Hideo , Wang Ziping , Hintze Thomas H.
Published: October 2002

Objective—

This study investigated whether cAMP signal transduction regulates coronary microvascular NO production after heart failure (HF), a state in which endothelial NO synthase (eNOS) is downregulated.

Methods and Results—

Myocardial microvessels were isolated. Nitrite, the hydration product of NO, from these vessels was quantified by using the Griess reaction. Forskolin (10
−4
mol/L), 8-bromo-cAMP (10
−2
mol/L), isoproterenol (10
−4
mol/L), or adrenomedullin (10
−6
mol/L) significantly increased nitrite release by 78±8, 84±14, 71±11, and 73±15 pmol/mg, respectively, from isolated microvessels from normal canine hearts (
P
<0.05 versus control). Bradykinin (10
−5
mol/L) and acetylcholine (10
−5
mol/L) increased nitrite release by 83±13 and 72±6 pmol/mg, respectively (
P
<0.05 versus control). However, NO production induced by bradykinin and acetylcholine was markedly reduced after HF (46±7 and 39±7 pmol/mg, respectively;
P
<0.05 versus normal), reflecting eNOS downregulation (55% in eNOS protein). Surprisingly, NO production in response to forskolin, 8-bromo-cAMP, isoproterenol, and adrenomedullin not only was preserved but also was substantially enhanced in these microvessels after HF (121±14, 124±21, 107±18, and 122±16 pmol/mg, respectively;
P
<0.05 versus normal group) and was associated with an upregulation of protein kinase B (220% increase in protein kinase B protein). All these responses were in an NO synthase or a protein kinase A inhibitor–blockable manner.

Conclusions—

Our data indicate that cAMP signal transduction may be an important potential compensatory pathway to increase myocardial microvascular NO production after HF when eNOS is downregulated.
Norepinephrine Elicits β
2
-Receptor–Mediated Dilation of Isolated Human Coronary Arterioles
Authors: Sun Dong , Huang An , Mital Seema , Kichuk Maryanne R. , Marboe Charles C. , Addonizio Linda J. , Michler Robert E. , Koller Akos , Hintze Thomas H. , Kaley Gabor
Published: October 2002

Background

—

The exact role of adrenoceptors in norepinephrine (NE)-mediated regulation of the human coronary circulation has yet to be elucidated. Thus, the goals of this study were to characterize the adrenoceptors involved in the responses to NE in isolated human coronary arterioles and small arteries.

Methods and Results

—

Arterioles (n=39) and small arteries from the left ventricle of explanted human hearts were isolated and cannulated. Vessels from the hearts of 21 patients were studied: 15 males and 6 females, aged 0.5 to 63 years. Nineteen patients were considered to be New York Heart Association class 4. All hearts exhibited hypertrophy (190±20%). The passive diameter of arterioles was 167±8 μm (range 97 to 323 μm). NE (10
−7
to 3×10
− 7
mol/L) elicited concentration-dependent dilations (47±4 μm) that were unaffected by endothelium removal,
N
ω
-nitro-
l
-arginine (10
− 4
mol/L, an NO synthase inhibitor), or practolol (10
−6
mol/L, a β
1
-receptor blocker). However, administration of propranolol (10
−5
mol/L, a combined β
1
- and β
2
-blocker) or butoxamine (10
−6
mol/L, a β
2
-receptor blocker) completely eliminated the NE-induced dilation. Constrictions to NE (2 of 39 vessels) were inhibited by prazosin (10
−6
mol/L, an α
1
-receptor blocker). Methoxamine (10
− 9
to 10
−5
mol/L, an α
1
-agonist) had no effect, whereas U44619, a thromboxane mimetic, elicited dose-dependent constriction of vessels.

Conclusions

—

Our data indicate that isolated human coronary arterioles and small arteries dilate to NE via β
2
-receptors on smooth muscle. These findings are important to our understanding of the mechanisms action of NE in the human coronary circulation.