bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Beam Recording beyond 200 Gbit/in2 Density for Next Generation Optical Disk Mastering
Authors: Katsumura Masahiro , Sato Megumi , Hashimoto Kazunobu , Hosoda Yasuo , Kasono Osamu , Kitahara Hiroaki , Kobayashi Masaki , Iida Tetsuya , Kuriyama Kazumi
Published: July 2005

We had developed an electron beam recorder for high-density mastering. The electron beam recorder has a capability to record high-density patterning beyond 200 Gbit/in2 density because it has characteristic of fine beam convergence. The behavior of electron scattering is important to realizing high-density patterning. Scattered electrons degrade patterning resolution and high-density patterning can not be realized. Thus, we adopted a new substrate made of a material that reduces the influence of the electron backscattering and attempted to record high density patterning beyond 200 Gbit/in2 density. As experimental result, 300 Gbit/in2 density patterning could be realized.
BD-Type Write-Once Disk with Pollutant-Free Material and Starch Substrate
Authors: Hosoda Yasuo , Higuchi Takanobu , Shida Noriyoshi , Imai Tetsuya , Iida Tetsuya , Kuriyama Kazumi , Yokogawa Fumihiko
Published: July 2005

We realized an inorganic write-once disk for an optical recording system of the Blu-ray disk format. We developed a new Al alloy for the reflective layer and a Nb-compound oxide nitride material for the dielectric layer. By adopting these materials for the reflective layer and the dielectric layer of our write-once disk, we achieved complete exclusion of toxic substances specified in the pollutant release and transfer register (PRTR) law. That is, this disk did not contain any substances specified in the PRTR law. We confirmed this disk to be compatible with 1× to 2× recording at the user capacity of 25.0 GB. The bottom jitter values of both 1× and 2× were less than 6.0%. In addition, we developed another kind of substrate, which was made of a natural polymer derived from corn starch. The bottom jitter value was 6.0% at the user capacity of 25.0 GB with the limit equalizer.
Construction of Injection Mold with MEMS RTD Sensor and MEMS Heater for Micro/Nano Molding Process
Authors: Kim Youngmin , Choi Yong , Kim Young-Joo , Kang Shinill
Published: July 2005

It is a very critical process to control the temperature of stamper surface in the micro/nano molding. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer greatly deteriorates the transcribability and fluidity of polymer melt. To improve the transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, an injection mold was prepared with microelectromechanical systems (MEMS) resistance temperature detector (RTD) sensor and MEMS heater to increase the stamper surface temperature over the glass transition temperature during the filling stage. We could control the stamper surface temperature up to 100°C within a few seconds using the fabricated MEMS heater. Finally, the high density optical disc substrates were replicated using the injection mold with MEMS heater and MEMS sensor.
Enhanced Scattering of Random-Distribution Nanoparticles and Evanescent Field in Super-Resolution Near-Field Structure
Authors: Li J. M. , Shi L. P. , Lim K. G. , Miao X. S. , Yang H. X. , Chong T. C.
Published: July 2005

This study focuses on evanescent fields induced by silver nanoparticles in the mask layer and in the interfaces in an AgOx-type super-resolution near-field structure (super-RENS). The finite-difference time-domain (FDTD) method is used to analyze the scattering fields from the localized surface plasmons of silver nanoparticles. It has been found that the spatial extension of the evanescent field is very short along the thickness direction of the layers, and the 3-dimensional coupling patterns of the evanescent fields from the individual particles are irregular. The study also found that the intensity of the evanescent fields is dependent on the silver concentration.
Characteristics of Flexible-Film Disks
Authors: Murata Shozo , Onagi Nobuaki , Aman Yasutomo
Published: July 2005

To achieve high-density recording with a high numerical aperture (NA) pickup, we produced a flexible optical disk system that has a small axial runout, enabling the pickup to follow the focal servo more easily. Young's modulus, the film thickness, and the position of the radius determine the rigidity of a film. Therefore, we defined the length to which a stabilizer pushing on a disk deformed the disk as the repellent force of the film and investigated the relationship between this repellent force and the axial runout of the disk. Consequently, by developing films with a specific repellent force, the axial runout of a variety of disks was reduced to less than 10 µm and high-density recording was achieved at a linear velocity of 13 m/s.
Improved Field-Emission Properties of Carbon Nanotube Field-Emission Arrays by Controlled Density Growth of Carbon Nanotubes
Authors: Juan Chuan-Ping , Chen Kuo-Ji , Tsai Chun-Chien , Lin Kao-Chao , Hong Wei-Kai , Hsieh Chen-Yu , Wang Wen-Pin , Lai Rui-Ling , Chen Kuei-Hsien , Chen Li-Chyong , Cheng Huang-Chung
Published: July 2005

The density distribution of CNTs is one of the crucial parameters determing the field-emission property of CNTs. To effectively control the density of CNTs, an inactive thin-film layer was deposited on a catalyst. The results showed that improved field emission property could be obtained with a thin SiO layer on the catalyst layer as the precursor. For 3.5 nm Fe and 3.5 nm SiO on 3.5 nm Fe as a catalyst, the turn-on field could be decreased from 3.7 V/µm. to 2.2 V/µm and the field-emission current density increased from 2.6×10-8A/cm2to 2.4×10-4A/cm2when the applied field was 4 V/µm
Optical and Electrical Characteristics of Organic Light-Emitting Diodes with Two-Dimensional Photonic Crystals in Organic/Electrode Layers
Authors: Fujita Masayuki , Ishihara Kuniaki , Ueno Tetsuya , Asano Takashi , Noda Susumu , Ohata Hiroshi , Tsuji Taishi , Nakada Hitoshi , Shimoji Noriyuki
Published: July 2005

Efficient light extraction is a critical issue for improving the overall efficiency of organic light-emitting diodes (OLEDs). Improvements in OLED efficiency are studied via the introduction of photonic crystal (PC) layers, which are expected to enable versatile control of photons. We fabricate two-dimensional PC structures in organic and electrode layers, in which most light is confined, to extract the light in the waveguide mode. Improvements in OLED efficiency of 20 and 130% are observed in spectrally integrated intensity and the peak intensity of forward-propagating light, respectively, in comparison with samples without PCs. As the thickness of the organic layer is partially reduced, lower operating voltages are found not to degrade light-extraction efficiency. We can expect further improvement in the overall OLED efficiency by optimizing PC structure.
Dual Drive and Emission Panel
Authors: Miyashita Takuya , Naka Shigeki , Okada Hiroyuki , Onnagawa Hiroyoshi
Published: July 2005

We propose double-faced organic light-emitting diodes (OLEDs) of a dual drive and emission (DDE) panel. Two OLEDs with two transparent electrodes for data signals and an intermediate reflective electrode for the common scan signal are independently operated. The typical structure of a stacking device is transparent electrode (1)/organic layer (1)/interlayer electrode/organic layer (2)/transparent electrode (2) on a glass substrate. Symmetric bright emission could be obtained using AlNd as the interlayer electrode and MoO3 as the hole injection layer for the upper OLED. The proposed device is useful for emissive double-faced panels displaying different images.
Organic Light-Emitting Microdevices Fabricated by Nanoimprinting Technology Using Diamond Molds
Authors: Kiyohara Shuji , Fujiwara Makoto , Matsubayashi Fumio , Mori Katsumi
Published: July 2005

The fabrication of organic light-emitting microdevices (micro-OLEDs) by nanoimprint lithography (NIL) using diamond molds fabricated by chemical vapor deposition (CVD) was investigated. The diamond molds used in the NIL process were fabricated with the Bi4Ti3O12 octylate (oxide) mask used in electron beam lithography technology. The diamond molds of convex dots of 30 µm square with 60 µm pitch were fabricated. The optimum imprint conditions were found to be as follows: imprinting pressure, press duration, substrate temperature and removal temperature of 0.8 MPa, 15 min, 180°C and 70°C, respectively. The device structure of 30-µm-square-dot OLEDs fabricated by imprinting is indium tin oxide (ITO) [anode]/poly(9-vinylcarbazole) (PVK) and coumarin-6 (C6) (0.1 µm thick) [hole transport and emitting layers]/8-hydroxyquinoline-aluminum (Alq) (50 nm thick) [electron transport layer]/aluminum (Al) (0.1 µm thick) [cathode]. The fabrication and operation of micro-OLEDs with 30 µm square dots in diamond-mold NIL were successfully demonstrated.
Relationships between Light-Emitting Properties and Different Isomers in Polymorphs of Tris(8-hydroxyquinoline) Aluminum(III) (Alq3) Analyzed by Solid-State 27Al NMR and Density Functional Theory (DFT) Calculations
Authors: Kaji Hironori , Kusaka Yasunari , Onoyama Goro , Horii Fumitaka
Published: July 2005

The structures of tris(8-hydroxyquinoline) aluminum(III) (Alq3) in the different polymorphs, α-, γ-, and δ-Alq3, and in the amorphous state, amo-Alq3, have been analyzed by solid-state 27Al nuclear magnetic resonance (NMR). The local structures of α- and amo-Alq3 are found to be similar; both samples are composed of the meridional isomer and are locally disordered. No evidence of the existence of the facial isomer is found even for amo-Alq3. In contrast, the isomeric states of γ- and δ-Alq3 are facial. The 27Al NMR spectrum of δ-Alq3 is influenced by intermolecular interactions, whereas that of γ-Alq3 is determined only by a single facial Alq3 molecule, suggesting that intermolecular interactions are negligible for γ-Alq3. This result is closely related to the experimentally observed good solubility of γ-Alq3. Density functional theory (DFT) calculations support the identification of the isomeric state and the effect of the intermolecular interactions. A clear correlation between the isomeric state and the fluorescence wavelength is found, indicating that the isomeric state of Alq3 is a crucial factor for the light-emitting properties.
Single-Crystal Field-Effect Transistors Based on Organic Selenium-Containing Semiconductor
Authors: Zeis Roswitha , Kloc Christian , Takimiya Kazuo , Kunugi Yoshihito , Konda Yasushi , Niihara Naoto , Otsubo Tetsuo
Published: July 2005

We report on the fabrication and characterization of single-crystal field-effect transistors (FETs) based on 2,6-diphenylbenzo[1,2-b:4,5-b']diselenophene (DPh-BDSe). These organic field-effect transistors (OFETs) function as p-channel accumulation-mode devices. At room temperature, for the best devices, the threshold voltage is less than -7 V and charge carrier mobility is nearly gate bias independent, ranging from 1 to 1.5 cm2/(V s) depending on the source-drain bias. Mobility is increased slightly by cooling below room temperature and decreases below 280 K.
Charge Injection Barrier Heights Across Multilayer Organic Thin Films
Authors: Murdey Richard J. , Salaneck William R.
Published: July 2005

Organic multilayer structures having a tetrathiafulvalene (TTF) or tetracyanoquinodimethane (TCNQ) interlayer were grown by physical vapor deposition on gold, indium tin oxide (ITO) or poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) PEDOT–PSS, substrates chosen to be representative of the anode materials typically used in the manufacture of organic electronic devices. The top layer was either p-quarterphenyl (Qp) or the hole transport material N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD). The valence electronic structure and vacuum level of the compound interface were monitored as a function of film thickness by ultraviolet photoelectron spectroscopy (UPS). Here we report the dependence of the energy level alignment on the substrate work function and discuss how an organic interlayer having a strong electron accepting or donating characteristic might be used to control the charge injection from a conducting electrode to a semiconducting organic hole transport material.
High Activation of Ga at Low Temperatures
Authors: Suzuki Kunihiro , Ebiko Yoshiki , Kataoka Yuji
Published: July 2005

We found that ion-implanted Ga was activated at a concentration of around 4×1019 cm-3, independent of annealing temperature. This active concentration is higher than the solid solubility at 500°C by about three orders. The activated Ga was deactivated during subsequent long-term annealing and approached its thermal equilibrium solid-solubility limit. Ga in the surface high-concentration region moved towards the surface and showed significant out-diffusion. We further evaluated the solid solubility limit of Ga, which we found to be much lower than the reported value.
Metal-Organic Vapor-Phase Epitaxy of Pseudomorphic InAlP/InGaAs High Electron Mobility Transistor Wafers
Authors: Sugiyama Hiroki , Yokoyama Haruki , Matsuzaki Hideaki , Enoki Takatomo , Kobayashi Takashi
Published: July 2005

InP-based high electron mobility transistor (HEMT) structures with a pseudomorphic InAlP barrier/spacer and an InGaAs channel were grown by metal-organic vapor-phase epitaxy (MOVPE). The thickness and composition of the InAlP/InGaAs heterostructure were optimized to reduce the gate-channel distance and obtain high electron mobility. The mobility of over 10000 cm2/V·s with the sheet carrier concentration (N
s) of around 2×1012 cm-2 was successfully obtained at room temperature in an In0.75Al0.25P/In0.75Ga0.25As pseudomorphic HEMT. The reliability of the InAlP layer as a gate-recess wet-etching stopper was also confirmed. The pseudomorphic In0.75Al0.25P-barrier/In0.75Ga0.25As-channel layer structure is suitable for practical ultrahigh-speed InP-based HEMTs.
Hydrogen Blister Formation on Cold-Worked Tungsten with Layered Structure
Authors: Nishijima Dai , Sugimoto Takanori , Ye Minyou , Ohno Noriyasu , Takamura Shuichi
Published: July 2005

Low-energy (<100 eV) and high-flux (>1021m-2s-1) hydrogen plasma exposures were performed on cold-worked powder metallurgy tungsten (PM-W), recrystallized cold-worked PM-W and hot-worked PM-W. Large blisters with a diameter of approximately 100–200 µm were observed only on the surface of cold-worked PM-W. The blister formation mechanism has not been clarified thus far. PM-W has a consisting of 1-µm-thick layers, which is formed by press-roll processing. A detailed observation of the cross section of those blisters shows for the first time that the blisters are formed by cleaving the upper layer along the stratified layer. These experimental results indicate that the manufacturing process of tungsten material is one of the key factors for blister formation on the tungsten surface.
Deposition of Pure Hydrogenated Amorphous Silicon by Plasma-Enhanced Chemical Vapor Deposition for Polycrystalline Silicon Thin Film Transistors
Authors: Hiramatsu Masato , Kimura Yoshinobu , Jyumonji Masayuki , Nishitani Mikihiko , Matsumura Masakiyo
Published: July 2005

A high-purity hydrogenated amorphous silicon film has been successfully deposited using an advanced plasma-enhanced chemical vapor deposition system that is available for mass-production use. Oxygen and carbon concentrations in the film were as low as 1.3×1017 and 2.6×1016 atoms/cm3, respectively, i.e., about hundredth part of the typical values achieved using a recent large-area deposition system and as low as those in CZ-Si wafers. The film was characterized as a function of SiH4 gas flow rate and outgas rate from the reaction chamber, and the results suggest that oxygen and carbon in the film comes predominantly from H2O and CO2 out-gassing from the chamber wall, respectively.
Multiposition Multipass Thomson Scattering Diagnostic for Tokamak NOVA-UNICAMP
Authors: Monteiro Marcelo J. R. , Machida Munemasa
Published: July 2005

In this article, the use of an 8×8-matrix independent 10-stage dynode multichannel photomultiplier for multipass Thomson scattering is described. Light from a pulsed ruby laser is irradiated 12 times in the central region of plasma using the resonator cavity of a multipass system, and integrated scattered light is detected for the first time using the multichannel photomultiplier XP1752 from Philips. The simultaneous measurements of electron temperature and density at four spatial positions, which can be extended by increasing the numbers of Analog-to-Digital Converter (ADC) channels and signal output windows, have been performed throughout full discharge by a shot-to-shot procedure. An electron temperature T
e of 50 eV and a density n
e of 5×1012 cm-3 were measured for the tokamak NOVA-UNICAMP. Because of the use of a low-power ruby laser (typically 1 J) and scattered light amplification using a multipass system, the level of stray light was kept low and absolute density measurements were made possible by nitrogen Rayleigh scattering.
Low-k SiOCH Film Deposited by Plasma-Enhanced Chemical Vapor Deposition Using Hexamethyldisiloxane and Water Vapor
Authors: Shioya Yoshimi , Shimoda Haruo , Maeda Kazuo , Ohdaira Toshiyuki , Suzuki Ryoichi , Seino Yutaka
Published: July 2005

We have developed low dielectric constant SiOCH films by plasma-enhanced chemical vapor deposition (PE-CVD) using hexamethyldisiloxane (HMDSO) containing a siloxane structure and water vapor (H2O) gases. Although the film was deposited using H2O vapor, the content of H2O is very small and the k value can be reduced to the order of 2.5. The leakage current is small and on the order of 10-9 to 10-10 A/cm2 at 1 MV/cm2. The hardness and Young's modulus are larger than 2 and 10 GPa, respectively at the k value of 2.8. However the values decrease abruptly with decreasing k value. The mechanism in which the structure and Young's modulus of PE-CVD low-k film decrease with changing k value and deposition conditions is discussed.
Experimental Study on the Universality of Mobility Behavior in Ultra Thin Body Metal Oxide Semiconductor Field Effect Transistors
Authors: Tsutsui Gen , Saitoh Masumi , Nagumo Toshiharu , Hiramoto Toshiro
Published: July 2005

This paper describes the mobility behavior in ultra thin body (UTB) silicon on insulator (SOI) p-type metal oxide semiconductor field effect transistors (pMOSFETs). We propose a method of detecting scattering mechanisms in UTB pMOSFETs, and experimentally demonstrate that the mobility in an 8.1-nm-thick SOI pMOSFET degrades due only to increased acoustic phonon scattering, while other degradation mechanisms appear in a 4.5-nm-thick device. It is also demonstrated that the mobility in the 4.5-nm-thick device shows universal characteristics as a function of an effective electric field for various substrate biases, which is the same behavior as that of bulk MOSFETs.
Effects of Dielectric Constant on Acid Generation in Chemically Amplified Resists for Post-Optical Lithography
Authors: Kozawa Takahiro , Okamoto Kazumasa , Saeki Akinori , Tagawa Seiichi
Published: July 2005

Acid generation in chemically amplified resists for post-optical lithographies such as electron beam and EUV lithographies is different from that in chemically amplified photoresists. In chemically amplified resists for post-optical lithographies, the role of acid generators is to produce not protons but counter anions of acids through reactions with low-energy electrons generated at ionization events. As the distribution of counter anions determines latent acid image, the dynamics of low energy electrons are important in post-optical lithographies. As the dynamics of low energy electrons are affected by the dielectric constant, the resist performance may be affected as well. In this study, we investigated the effect of dielectric constants of base polymers on the sensitivity and resolution of chemically amplified resists. The electron dynamics were simulated using the Smoluchowski equation. The efficiency of acid generation and the distribution of acids (resolution blur) are discussed in terms of the dielectric constant. The simulation results predict that the acid yield increases and the resolution blur decreases slightly with an increase in the dielectric constants.
Magnetic Compton Scattering Studies of Electrochemically Hydrogenated Nickel
Authors: Mizusaki Soichiro , Miyatake Taichi , Sato Naotoshi , Yamamoto Isao , Itou Masayoshi , Sakurai Yoshiharu , Yamaguchi Masuhiro
Published: July 2005

The influence of hydrogen absorption on the electronic and magnetic states of nickel was investigated by using the magnetic Compton scattering method, associated with band structure calculation. Hydrogen-free, hydrogen-charged and hydrogen-discharging nickel foils were prepared in an electrochemical cell, then their magnetic Compton profiles (MCPs) were measured with circularly polarized 173 keV X-rays in magnetic fields of ±2.5 T at room temperaturein situ. The MCP of the hydrogen-charged nickel was separated into the respective profiles of α-phase NiH0.03and β-phase NiH0.7. The MCP of the β-phase NiH0.7indicates that this hydride is weakly ferromagnetic with a small spin moment µ<0.1 µB/Ni where the positive d-like component is nearly cancelled out by the negative s,p-like component. The band structure calculation yields such a small moment in the hydrogen-ordered NiH0.75, but smaller absolute values of the d-like and the sp-like components than the observed ones.
Proposal for Ultrabroadband Phase-Matching Optical Parametric Chirped Pulse Amplification with a Diverged Pump Beam
Authors: Harimoto Tetsuo , Yamakawa Koichi
Published: July 2005

We propose a novel scheme for optical parametric chirped pulse amplification with a diverged pump beam to achieve an ultrabroadband phase-matching range, in which different signal wavelengths correspond to different inclination angles of the diverged pump beam. Simulation results show that the proposed scheme amplifies a signal pulse shorter than 10 fs at a wavelength of approximately 800 nm.
Proposed Configuration of Optical Isolator with TiO2/Magnetic Garnet Waveguide
Authors: Yokoi Hideki
Published: July 2005

An optical isolator with a TiO2/magnetic garnet waveguide obtained using nonreciprocal phase shift was proposed. The magnetooptic waveguide had an air/TiO2/magnetic garnet structure in which magnetic garnet was used as a lower cladding layer. Nonreciprocal phase shift in the magnetooptic waveguide was calculated at a wavelength of 1.55 µm. A magnetooptic waveguide with a TiO2/magnetic garnet guiding layer was also investigated. The required propagation distance for isolator operation was less than that of the optical isolator with the air/TiO2/magnetic garnet waveguide.
Kernel Adjusted Wiener Filter for Image Enhancement
Authors: Song Young-Chul , Choi Doo-Hyun
Published: July 2005

A modified Wiener filtering method is proposed for resolution enhancement without any loss of the peak signal-to-noise ratio (PSNR), whereby the filtering strength applied to the edge region is adjusted using a modified filter kernel. In spite of the increased filtering strength in the edge region, strong edges are still preserved. Compared to the conventional Wiener filter, the modified Wiener filter provides higher PSNR and better subjective image quality in the filtered image.
Electrical Properties of Holmium-Doped BaTiO3
Authors: Jeong Jaill , Lee Eun Jung , Han Young Ho
Published: July 2005

The effects of Ho (holmium) doping on the electrical properties and microstructural development of (Ba1-x
Ho
x
)TiO3 were investigated by means of defect chemistry on the basis of equilibrium electrical conductivity data measured at 1300°C, as a function of oxygen activity. Ho2O3 additions to BaTiO3 up to 0.3 mol% were compensated by electrons under all oxygen partial pressures and the samples exhibited a low insulating resistance at room temperature. However, at Ho>0.3 mol%, the compensation mode switched from electrons to cation vacancies in the region of high oxygen partial pressure. The solubility limit of HoBa
• was confirmed to be less than 3.0 mol%. The specimens doped with Ho<0.5 mol% had a low insulating resistance and large grains, whereas high insulating resistance and fine grains were observed in the samples doped with Ho grater than 0.5 mol%.
Br K-Edge X-ray Absorption Near Edge Structure Analyses of Bromine Residue Carbon Compounds Using Full Multiple-Scattering Theory
Authors: Uno Kanae , Notoya Yasuharu , Fujikawa Takashi , Yoshikawa Hidetaka , Nishikawa Keiko
Published: July 2005

A recent experimental result shows that Br K-edge X-ray absorption near edge structure (XANES) spectra for bromine residue compounds are sensitive to the heat treatment of host carbon compounds. In the present study we attempt to extract useful information on the geometric and electronic structures of these systems by applying a full multiple-scattering approach to XANES analyses. The residue compounds can be classified into three groups on the basis of XANES spectral features. Present detailed analyses provide us some useful information: Group 1, bromine residue compounds are prepared from host carbon compounds heat-treated at 2000–2800°C, where Br2 molecules exist in the interlayer space of graphite. The interlayer distance expands to about 7.8 Å around the Br2 molecules. For heat treatment at 1900°C, the observed spectra are well explained by the superposition of the spectrum for Group 1 and that for Group 2, with a ratio of 3:4. For Group 2 heat-treated at 1500–1750°C, the host carbon compounds includes Br- ions, but no information on the Br-–C correlation has been obtained. For Group 3 heat-treated at 1000°C, the host carbon compounds mainly includes HBr molecules parallel to small aromatic carbon molecules.
High-Efficiency Carrier Injection Characteristics of Dixanthene Derivatives in Organic Light-Emitting Diodes
Authors: Yoshida Masafumi , Tsuchida Teppei , Kurata Takaaki , Ikeda Masaaki , Sasabe Hiroyuki , Adachi Chihaya
Published: July 2005

We demonstrate that benzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX) derivatives show high-efficiency carrier injection in organic light-emitting diodes (OLEDs). Using 3,11-dibromobenzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX6) as a hole injection layer (HIL), we achieved a low driving voltage of 8.12±0.10 V in obtaining a current density of J=100 mA/cm2. The hole injection characteristics were superior to those of a device with a conventional CuPc layer as a HIL. On the other hand, inserting benzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX1) as an electron injection layer (EIL) efficiently decreased driving voltage, indicating a superior electron injection capability compared with a device without a BDX1 EIL. We show that carrier injection efficiency can be well controlled by the substituent groups of BDX, thus providing efficient hole and electron injection layers.
Carbon Microstructures Synthesized Utilizing the RF Microplasma Jet at Atmospheric Pressure
Authors: Yang Zhongshi , Kikuchi Tomoyuki , Hatou Yasuhiro , Kobayashi Tomohiro , Shirai Hajime
Published: July 2005

A novel rf microplasma jet was successfully generated at atmospheric pressure using a single-tube electrode. Preliminary results of the application of the microplasma jet to the synthesis of carbon microstructures using a CH4 and Ar mixture are presented with the following variables: the inner hole diameter of the needle tube electrode, the flow rate of methane, and substrate temperature. Carbon microstructures such as diamond particles, carbon nanowires, carbon nanotubes and cone-shaped crystalline Si, were synthesized with wide surface distributions by adjusting the deposition parameters. The relationship between the plasma state and the silicon and carbon microstructures and their surface distribution is demonstrated.
Ion Temperature Measurement Using Ion-Sensitive Probe
Authors: Tsushima Akira , Tayama Yuichi
Published: July 2005

The ion current of ion-sensitive probes is investigated on the basis of a numerical analysis of ion orbits. Each ion-sensitive probe investigated in this study consists of a central electrode and a guard electrode, which are biased to an identical potential, V, against ambient plasma. By fitting an expected function, given by I=I
0exp
[-c(e
V/k
B
T
i)], to numerically obtained V–I characteristics of each ion-sensitive probe, we obtain a calibration coefficient, c, for measurement of ion temperature, T
i, and consider the validity of the fitting. Since the calibration coefficient depends on the radius and height of the guard electrode, the layout of the ion-sensitive probe for a reliable measurement of ion temperature is discussed.
Fabrication of Interpenetrating Semilayered Structure of Conducting Polymer and Fullerene by Solvent Corrosion Method and Its Photovoltaic Properties
Authors: Umeda Tokiyoshi , Hashimoto Yuuki , Mizukami Hiroyoshi , Fujii Akihiko , Yoshino Katsumi
Published: July 2005

Photovoltaic cells with an interpenetrating interface between a conducting polymer layer and a fullerene layer fabricated by a solvent corrosion method have been investigated. Using a weakly dissoluble combination of a solvent and an underlayer film, we fabricated a “semilayered” structure that maintained a bilayer structure and interpenetrated at the interface of the conducting polymer and the fullerene layers. Poly(3-hexylthiophene) (PAT6) or poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) were used as the conducting polymer layer and C60 was used as the fullerene layer. In these cells, high external quantum efficiencies (EQEs) were obtained because of efficient exciton dissociations at the interpenetrating interface and efficient carrier transports by each continuous pathway between fullerene molecules of electrons and between conducting polymers of holes. An improvement was achieved by inserting a zinc oxide layer with an appropriate thickness between ITO and fullerene layer. From the comparison between the absorption spectra and the obtained EQE, the ratio of the contribution of each absorption to photocurrent was estimated. The photovoltaic properties were found to be dependent on the solvent used and corrosion time, which have been discussed by taking the form and the degree of corroded interpenetrating interface into consideration.
Electrical Conductivity of Polymer Composites Filled with Metal
Authors: Horibe Hideo , Kamimura Tomosumi , Yoshida Kunio
Published: July 2005

Conductive polymer composites filled with conductive filler particles exhibit a positive temperature coefficient (PTC) effect. It is desirable to develop these composites with a low resistivity at room temperature and a high resistivity after polymer melting. We evaluated the relationships between the PTC properties of the composites and the type of the metal, the particle size of the metal, and the metal content. Among metals containing composites evaluated in this study, the composite consisting of tungsten (W) showed the best PTC properties. Then we compared the PTC properties between the composites consisting of W and of CB. The composite consisting of W has a lower resistivity at room temperature and a higher resistivity after polymer melting than that consisting of CB. Generally, the composite which has a low resistivity at room temperature has a low resistivity after polymer melting. We developed the composite consisting of high-density polyethylene (HDPE)/W = 59/41 vol% (7/93 wt%), which showed a 0.01 Ω cm resistivity at room temperature, and a 105Ω cm resistivity after polymer melting. This composite has no negative temperature coefficient effect after polymer melting.
Dispersion Behaviors of Antisymmetric Flexural Modes Propagating along Wedges with Bilinear Cross Sections
Authors: Yang Che-Hua , Tsen Chun-Zen
Published: July 2005

This study is focused on exploring the dispersion behaviors of anti symmetric flexural (ASF) modes propagating along a bilinear wedge (BW). A BW is wedge whose cross section has two apex angles, as opposed to a linear wedge (LW) whose cross section has a single apex angle. In the literature, many studies regarding the dispersion behaviors of ASF modes have been reported for LWs, but not for BWs. In this study, a laser ultrasonic technique is used to investigate the dispersion behavior of BW-ASF modes. It is determined that a BW-ASF mode arises as a result of mode coupling between two LW-ASF modes of the same order corresponding to the two apex angles of the BW.
Electroluminescence Spikes of Pulsed Organic Light-Emitting Diodes at Switch-Off Using 1,4-Bis[2-[4-[N,N-di( p-tolyl)amino]phenyl]vinyl]benzene as a Light-Emitting Layer
Authors: Wei Bin , Horiba Yashuhiro , Furukawa Kenji , Ichikawa Musubu , Koyama Toshiki , Taniguchi Yoshio
Published: July 2005

The electroluminescence (EL) spikes from low-molecular organic light-emitting diodes (OLEDs) at the switch-off of applied pulse voltage using 1,4-bis[2-[4-[N,N-di( p-tolyl)amino]phenyl]vinyl]benzene (DSB) as an emission layer were observed. The characteristics of EL spikes, such as their duration and magnitude, were studied by changing the device structure of the OLEDs and the conditions of the applied voltage. The duration of the EL spikes was found to depend on the species of electron transport layer but to be independent of the amplitude of the applied voltage. The magnitude of the EL spikes increased with the applied time up to a saturated state, which was significantly determined by the thickness of the emitting layer. The trapezoid pulse voltage was found to be an effective tool for predicting the charge accumulation in the interfacial layer.
Ultrasonic Study of Machinable Ceramic over Temperature Range from Room Temperature to 1000°C
Authors: Kashiwagura Nobuo , Akita Masayuki , Kamioka Hiroaki
Published: July 2005

Shear and compressional velocities and the attenuation of a 0.5 MHz ultrasonic wave in a machinable ceramic were accurately measured by the pulse transmission method over the temperature range from 30°C to 1000°C. The temperature dependence of the compressional and shear wave velocities and attenuation exhibits a marked feature around the glass transition temperature. The temperature dependence of the elastic modulus was calculated from the ultrasonic data. The elastic properties of the machinable ceramic at high temperatures are shown.
Lead Zirconate Titanate Thick-Film Ultrasonic Transducer for 1 to 20 MHz Frequency Bands Fabricated by Hydrothermal Polycrystal Growth
Authors: Ishikawa Mutsuo , Kurosawa Minoru Kuribayashi , Endoh Akito , Takeuchi Shinichi
Published: July 2005

A thickness vibration mode ultrasonic transducer was fabricated by hydrothermal deposition of lead zirconate titanate polycrystalline thick film. This hydrothermal polycrystalline PZT thick-film (HPTF-PZT) ultrasonic transducer was studied for its wide-frequency-band transmission characteristics. The transducer had a 50-µm-thick PZT layer on a 50-µm-thick titanium substrate in an active area of 8 mm×8 mm. The experimental results showed the HPTF-PZT ultrasonic transducer radiated a single ultrasound pulse in the frequency range from 1 to 20 MHz with a 20 dB deviation. Additionally, this transducer generated a 2 MHz sawtooth ultrasonic wave with odd-and even order-harmonic components from the 2nd to the 11th harmonics. These results indicate that the fabricated ultrasonic transducer has satisfactory wide-band characteristics for a MHz frequency range ultrasonic transmitter.
Ultrasonic Measurement System for Detecting Penetration of Boulders by Autocorrelation Analysis
Authors: Kawamura Youhei , Tsurushima Mamoru , Mizutani Koichi , Ujihira Masuyuki , Aoshima Nobuharu , Kuraoka Senro
Published: July 2005

An elastic impact wave method is used as a typical nondestructive test method to investigate the depth of boulder penetration. However, in the elastic impact wave method using, for example, a hammer, the discrimination of the reflection wave produced by minute cracks is difficult. Theoretically, if it becomes possible to input the vibration of an ultrasonic domain into artificial structures, such as a concrete and a boulder, with a strong amplitude, deeper investigation depth compared to the conventional way with a high precision will be attained. In this study, a concrete block, with a known size, which was, unlike boulders, not buried under ground, was used as a test piece in a basic experiment. As analysis methods, a wavelet analysis for checking the reflection wave and an autocorrelation analysis for identifying the time lag of the reflection wave were used. As a result, the reflection wave was detected in a down chirp signal from 50 kHz to 40 kHz.
A Super-Precise CTE Evaluation Method for Ultra-Low-Expansion Glasses Using the LFB Ultrasonic Material Characterization System
Authors: Kushibiki Jun-ichi , Arakawa Mototaka , Ohashi Yuji , Suzuki Kouji , Maruyama Takahisa
Published: July 2005

A super-precise method of evaluating the coefficient of thermal expansion (CTE) of ultra-low-expansion glasses for future extreme ultra-violet lithography (EUVL) systems was developed using the line-focus-beam ultrasonic material characterization (LFB-UMC) system. Evaluation was demonstrated for two commercial glasses, TiO2-SiO2 glass (C-7971) and Li2O-Al2O3-SiO2 glass ceramic (Zerodur). For the C-7971 specimens, the sensitivity and resolution in the velocity measurement of leaky surface acoustic waves (LSAWs) for the CTE were estimated to be 4.40 (ppb/K)/(m/s) and ±0.77 ppb/K for ±2σ (σ: standard deviation). LSAW velocity differences caused by different TiO2 concentrations and distributions or striae in each specimen were successfully detected and evaluated. For the Zerodur specimens, LSAW velocity differences associated with the chemical compositions and crystallization conditions were observed among different ingots and specimens. This ultrasonic method is expected to be an extremely useful and effective CTE evaluation technology and to contribute to improving and developing EUVL-grade glass materials.
Simulation and Analysis of Subharmonics and Tail Effect for Ultrasonic Nondestructive Evaluation of Closed Cracks
Authors: Sasaki Ryouta , Ogata Toshihiro , Ohara Yoshikazu , Mihara Tsuyoshi , Yamanaka Kazushi
Published: July 2005

Subharmonics are generated at closed cracks by the nonlinear effect of large-amplitude ultrasound. This effect has the possibility of more accurate detection and evaluation of closed cracks. Also, it was reported that the tail part of the transmitted wave through the cracks has a peculiar wave, which is called the “tail effect”. Thus far, the mechanisms of the tail effect have not been revealed. In this paper, we introduced a realistic input wave into the previous model, which shows the interaction between closed cracks and large-amplitude ultrasound. As a result, we reproduced both the subharmonics and the tail effect for the first time. Furthermore, the mechanism was verified by comparing the input and output waveforms and using a potential energy diagram. Based on these findings, we proposed novel approaches for nondestructive evaluation of closed cracks.
Error Analysis for Micrometeorological Measurements Using Bidirectional Sound Probe with Long Baseline in Wind Fields
Authors: Itoga Kazuya , Mizutani Koichi , Wakatsuki Naoto , Kudo Kousuke
Published: July 2005

We estimated the measurement errors caused by the errors in time of flight (TOF) and length of the baseline, in meteorological measurement using bidirectional sound probes with a long baseline. In addition, we simulated the measurement in three types of spatial wind distribution, using simple ray tracing. TOFs and the length of the sound ray were calculated for the three wind distributions. The calculated values of air temperature and wind velocity component derived from the TOFs and the length of the ray, were compared with their line-averaged values along the baseline. The results show good agreement. The errors were approximately -0.7°C for the air temperature and approximately -0.01 m/s for the wind component even in wind fields where a 20 m/s wind exists on the baseline. This indicated that the bidirectional-sound probe with a long baseline could satisfactorily carry out micrometeorological measurement in wind fields using conventional calculations.
Nanometer-Order Resolution Displacement Measurement System by Air-Coupled Ultrasonic Wave Introducing Maximum Phase-Sensitivity Tuning
Authors: Sasaki Katsuhiro , Nishihira Morimasa , Imano Kazuhiko
Published: July 2005

An improved system introducing an automatic tuning of the maximum phase sensitivity of ultrasonic signals is constructed for detecting displacements with a nanometer-order resolution. The phases of multiple-reference waves introduced in our previous system are controlled and appropriately set to tune the phase sensitivity. To evaluate our system, the displacement of a high-precision mechanical stage was measured using 40 kHz air-coupled ultrasonic waves. The resolution of the phase detection for our system is improved more than ten times our previous system. A resolution of 40 nm (λ/200,000) displacement has been achieved with a measurable displacement range of 8 mm (≃λ).
Experimental Study on Ultrasonic Computed Tomography Using Transducers Arrayed on the Internal Surface of a Cylinder
Authors: Kim Jung-Soon , Kim Moo-Joon , Kim Jung-Ho , Ha Kang-Lyeol
Published: July 2005

In this study, ultrasonic array transducers with 32 vibrators arranged on the internal surface of a part of a cylinder were fabricated. The vibrators were operated by the piezoelectric transverse effect. By controlling the phase of the input signal for every vibrator, a quasi plane wave was synthesized. Using the fabricated array, inverse scattering ultrasonic computed tomography (UCT) was carried out with a phantom specimen after checking the plane wave generation. It was confirmed that the plane wave was synthesized successfully and a sound velocity image of the phantom was obtained by the plane wave. Consequently, it was noted that the array could be employed as a transmitter and receiver for data acquisition in UCT.
Label Recognition with Wavelength-Selective Collinear Acoustooptic Switches for Photonic Label Routers
Authors: Goto Nobuo , Miyazaki Yasumitsu
Published: July 2005

Collinear acoustooptic (AO) switches have a feature of wavelength-selective switching for wavelength-division-multiplex (WDM) signals. This feature can be used for photonic packet routing in a WDM photonic network. In this paper, application of the collinear AO switches to a label recognition processor in a photonic routing system is investigated. The optical label uses optical codes which are encoded in the spectral domain. The collinear AO switch is considered to be useful for label recognition by using multiple wavelength switching with multiple frequency rf control signals. The switched and unswitched optical signals are processed with a balanced photodetector. A numerical example for the code recognition is presented.
Diffraction Properties and Beam-Propagation Analysis of Waveguide-Type Acoustooptic Modulator Driven by Surface Acoustic Wave
Authors: Kakio Shoji , Uotani Shinji , Nakagawa Yasuhiko , Hara Takefumi , Ito Hiromasa , Iizuka Takashi , Kobayashi Tetsuya , Watanabe Masayuki
Published: July 2005

A waveguide-type acoustooptic modulator (AOM) driven by a surface acoustic wave (SAW) in a tapered crossed-channel waveguide on a 128°-rotated Y-cut LiNbO3 substrate has been proposed for an optical wavelength of 1.55 µm. In this study, to clarify the conditions for a higher diffraction efficiency and a lower driving power, the diffraction properties of the waveguide-type AOM were measured and simulated. First, an AOM with an AO interaction region length of 3 mm was fabricated and the diffraction efficiency of 65% was obtained. Next, the measured values of the SAW power required for 100% diffraction (P
100) for the driving frequencies of 125 MHz and 200 MHz were found to be in agreement with the calculated P
100, which shows that there is an optimum driving frequency. Furthermore, optical frequency domain ranging using a frequency-shifted-feedback fiber laser with the waveguide-type AOM was demonstrated. Finally, the diffraction properties of the waveguide-type AOM are simulated using a beam-propagation method (BPM) and compared with the experimental results.
Numerical Formulation of the FDTD Method for Transient Analysis of Elastic Wave Fields in the Y-Z Plane of Quartz
Authors: Sato Masahiro
Published: July 2005

The present study derives a formulation of the finite-difference time-domain (FDTD) method appropriate for analyzing the transient behavior of elastic wave fields in the Y-Z plane of Quartz. It is shown that this formulation may easily be adapted for use on arbitrary anisotropic solids.
The staggered lattice network of the present study differs from that of an isotropic solid only in the requirement of two variables on a particle velocity node and three variables on a stress node, in contrast to the isotropic case of one variable on a particle velocity node, and two or one variables on a stress node.
Two model problems are considered which allow results obtained by the present numerical method to be compared with analytical predictions. The first model is constructed to test whether the FDTD formulation correctly captures the direction of energy flow for longitudinal and shear plane waves. This direction differs from that of the wave number vector. The second model is constructed in order to test whether the FDTD formulation correctly captures the dependence of phase velocity on the wave number vector. The results obtained from the numerical method are shown to be in excellent agreement with the analytical predictions.
Resonance Patterns of Piezoelectric Partial-Drive Systems without Mechanical Impedance Matching
Authors: Ohki Michio
Published: July 2005

The mathematical rules about resonance frequencies and intensities are investigated for partially-driven piezoelectric transducers with mechanical impedance-mismatch layers inside the transducer. The concepts of (arithmetic) location rules, density and period of resonance pattern are introduced, and some mathematical rules with regard to these quantities are found out, which should be considered when the transducer is designed and analyzed.
Two-Dimensional Analysis of Coupled Vibrations of UHF AT-Cut Quartz Plates with Electrodes of Plano-Mesa Shape
Authors: Sekimoto Hitoshi , Onozaki Yoshihisa , Tamura Takeshi , Goka Shigeyoshi , Watanabe Yasuaki
Published: July 2005

We numerically analyze the influence of both plate and electrode edges on unwanted coupling between fundamental thickness-shear (TS) and spurious modes. Classical mode-matching is utilized to solve the two-dimensional coupled vibrations of an AT-cut quartz plate with strip electrodes of plano-mesa shape. Using this technique, we calculate the minimum frequency differences between TS and flexural (F) or extensional (E) resonances as a function of electrode thickness. The results reveal that, with increasing electrode thickness, the origin of unwanted coupling between TS and F modes shifts from the plate edges to the electrode edges, while TS- and E-mode coupling is caused only by the electrode edges and it therefore closely correlates to the inverse of quality factor Q derived from modeling an infinite plate. We also find that there is an index of electrode thickness that suppresses both F and E components coupled with the TS mode.