bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation and Electrooptic Characteristics of M-ttbPc LB Films
Authors: Higo Tomoyuki , Ikehara Takashi , Irokawa Katusmi , Yamashita Masafumi
Published: September 2005

Ultrathin films of tetra-tert-butyl-phthalocyaninato-iron (FettbPc) mixed with promoting stearic acid (SA) were deposited on clean and Al-coated glass substrates by the Langmuir-Blodgett (LB) method. The LB films were investigated by X-ray diffraction (XRD) analysis, UV-visible spectroscopy and FT-IR to determine their structures and to analyze the optical and electrical properties. The photovoltaic efficiencies of solar cells composed of Al/FettbPc:SA LB film/Au and Al/CuttbPc:SA LB film/Au were 1.65×10-5% and 3.20×10-6%, respectively. The junctions at Al/Pc seem to be disrupted by interfacial layers of Al2O3. The magnitudes of the efficiencies were smaller than those of Al/In/M-Pc/Au cells, fabricated by an evaporation method, by a factor of 2 or 3.
Transparent Organic Light-Emitting Devices Fabricated by Cs-Incorporated RF Magnetron Sputtering Deposition
Authors: Uchida Takayuki , Mimura Toshifumi , Kaneta Shingo , Ichihara Masahiro , Ohtsuka Masao , Otomo Toshio
Published: September 2005

For the cathode of a transparent organic light-emitting device (TOLED), an indium–tin oxide (ITO) film was deposited using RF magnetron sputtering with Cs vapor introduction during the sputtering process. The work function of the Cs incorporated ITO film was 4.3 eV with electric conductivity and it was very stable in an atmospheric environment over an extended period of time. It was shown that this Cs incorporation technique was effective for the incorporation of Cs in an ITO film and that it resulted in an ITO film with a low work function. The TOLED fabricated with ITO:Cs as a cathode showed a much higher electron injection efficiency than currently used devices with an alkali-metal doped organic layer at low current density.
Simulation for Reset Operation of Ge2Sb2Te5 Phase-Change Random Access Memory
Authors: Kim Sung Soon , Jeong Seong Min , Lee Keun Ho , Park Young Kwan , Kim Young Tae , Kong Jeong Taek , Lee Hong Lim
Published: September 2005

The reset operation of phase-change random access memory (PRAM) was simulated by the finite element method. The dominant variables for optimizing reset operation were proved to be not only the reset current but also the shape of the formed amorphous region in the writing layer. The connection of the electrical resistances through the crystal and/or the formed amorphous region in the writing layer was found to depend on the shape of the formed amorphous region. The classical nucleation theory and Monte Carlo method were used to evaluate the nucleation during the quenching step by simulation. It is considered that considerable nucleation occurs during the quenching step. It is also predicted that nuclei formed during the quenching step may reduce the incubation time in the crystallization step.
Reoxidation after NH3 Plasma Nitridation for Multiple-Thickness Oxynitrides
Authors: Lai Chao Sung , Fan Kung Ming
Published: September 2005

A novel manufacturable multiple gate oxynitride thickness technology is proposed in this work. An ultrathin dielectric film (E
OT=2.5 nm) of lower oxidation growth rate than conventional films was fabricated by NH3 plasma nitridation. Oxide thickness was reduced by about 80% for samples treated by NH3 plasma nitridation. However, the thickness limitation is 1.3 nm for NH3 plasma nitridation. This is believed to be due to nitrogen incorporated in the silicon surface to form a nitridelike thin film, which retarded oxide growth. The effects of NH3 plasma nitridation were systematically studied, and the rapid thermal N2O reoxidation of an NH3 plasma sample was also demonstrated in this work. This novel process improves the gate oxide reliability, decreases bulk trap densities, provides better SILC immunity, and produces less charge trapping and a higher Q
bd.
Practical High-Resistivity Silicon-on-Insulator Solution for Spiral Inductors in Radio-Frequency Integrated Circuits
Authors: Kodate Junichi , Douseki Takakuni , Tsukahara Tsuneo , Okabe Takehito , Sato Nobuhiko
Published: September 2005

The effect of high-resistivity (high-R) silicon-on-insulator (SOI) substrates on spiral inductors in radio-frequency integrated circuits (RF ICs) has been investigated by experiment and simulation. The effect of the high-R substrates on the spiral inductors saturates at a resistivity above 2–3 kΩ cm, and the resistivity must be maintained high with a thickness of about 300 µm. The resistivity dependence of the high-R effect can be explained with a dielectric loss mechanism in silicon substrates. The thickness criterion of the effect can be explained with an inductor model that includes magnetically induced current in a ground plane. On the basis of experimental results and discussion, we conclude that a commercially available high-R wafer with carefully designed back-end process is sufficient for obtaining the maximum effect of high-R substrates.
Superimposition of Different Pinning Mechanisms by Combined Additives in Sm–Ba–Cu–O Superconductors
Authors: Chen Shih-Yun , Hsieh Ping-Chi , Chen In-Gann , Wu Maw-Kuen
Published: September 2005

The critical current density (J
c) of melt-textured growth (MTG) RE–Ba–Cu–O (RE: rare earth elements) materials is strongly affected by the pinning mechanisms of various defects associated with microstructual variations. In this study, different additives were used, such as (a) 0.5 wt % Pt/1.0 wt % CeO2 (A1), (b) nano sized Sm2BaCuO5 particles (N1), and (c) co doping of A1 and N1 (C1). The influence of individual addition of A1 and N1 species was studied. Enhancement in the J
c–H curves was shown for both types of additives, however, at different magnetic fields. Microstructural studies showed that the size of 211-particle decreased and the number of particles increased significantly in the A1 samples, which resulted in increasing dislocations and stacking fault density (known as δl pinning) associated with the 211/123 interfaces. On the other hand, in the N1 sample, nano scale compositional fluctuation of Sm1+x
Ba2-x
Cu3O
y
(where x as well as T
c varied on the nanometer scale) was proposed to result in δT
c pinning. The study shows that two types of pinning centers (δl of the A1 sample and δT
c of the N1 sample) can be superimposed by the combined addition of both additives. Thus, a high J
c at different fields can be achieved due to the activation of different pinning centers.
Epitaxial Growth of Fe/MgO/Fe Heterostructures on SrTiO3(001) Substrates by Magnetron Sputtering
Authors: Marukame Takao , Matsuda Ken-ichi , Uemura Tetsuya , Yamamoto Masafumi
Published: September 2005

We report on the preparation and structural properties of MgO/Fe bilayers (a MgO thin film on an Fe thin film), Fe/MgO bilayers (an Fe thin film on a MgO thin film), and Fe/MgO/Fe trilayers, all grown by magnetron sputtering on SrTiO3(001) substrates. We investigated the structural properties of these heterostructures with X-ray diffraction (XRD) (θ–2 θ scan, rocking curve and pole figure measurements), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). Single-crystalline epitaxial growth was confirmed by the X-ray pole figure measurements for both the MgO/Fe and Fe/MgO bilayers, which were the basic layer components for the Fe/MgO/Fe trilayer. The cross-sectional HRTEM clearly indicated epitaxial growth of the Fe/MgO/Fe trilayer structures on the SrTiO3(001) substrates with excellent flat interfaces having roughness of less than a few angstroms.
Embedded Micro-Flux-Gate Magnetic Sensor in Printed Circuit Board
Authors: Choi Won-Youl , Hwang Jun-Sik , Choi Sang-On
Published: September 2005

We have developed a micro-flux-gate magnetic sensor using a new printed circuit board (PCB) technology. The flux-gate sensor consists of five PCB stack layers including one layer of magnetic core and four layers of excitation and pickup coils. The center layer as a magnetic core is made of a micropatterned amorphous magnetic ribbon with an extremely high DC permeability of ∼100,000; the core has a rectangular ring shape. The four outer layers as excitation and pickup coils have a planar solenoid structure. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path of the excitation field. The chip size of the fabricated sensing element is 9.8 ×5.7 mm2. Excellent linear response over the range of -100 to +100 µT is obtained with 1460 V/T sensitivity at an excitation sine wave of 3 Vp–p and 360 kHz. A low power consumption of ∼10 mW was measured.
Mechanically Tunable Fiber-to-Tapered Planar Waveguide Coupler
Authors: Kim Kwang Taek , Lee Kyu Hyo , Hwangbo Sueng , Kweon Gyeong-il
Published: September 2005

A fiber-to-tapered planar waveguide (PWG) coupler whose resonance wavelength and depth can be mechanically tuned is proposed and demonstrated. The resonance wavelength is controlled by changing the PWG thickness, while the extinction ratio is controlled by varying the coupling length between the fiber and the PWG. The effect of PWG thickness variation along the fiber direction on the resonance sharpness is also investigated. The fabrication techniques and experimental results are presented in detail, along with a short discussion on the potential applications of the device.
Fluctuation of the Carrier-Envelope Phase of a Few-Cycle Laser Pulse from a Chirped-Pulse Amplification System with the Gas Pressure in a Hollow Fiber
Authors: Ishizawa A. , Nakano H.
Published: September 2005

We experimentally confirmed that additional CEP fluctuations induced in a hollow fiber increased with gas pressure. A gas pressure in the hollow fiber of between 2 and 2.5 atm results in both a short-pulse generation and the small CEP fluctuation. We also measured the carrier-envelope phase (CEP) fluctuations of spectrally broadened intense pulses that passed through a hollow fiber. An additional carrier-envelope phase fluctuation of 0.12 rad was induced in white light generated in the hollow fiber under the optimum gas pressure.
Tuning of Channel Spacing in Sampled Fiber Gratings by Heat-Induced Multiple-Phase-Shift Technique
Authors: Yamashita Shinji , Yokooji Muneo
Published: September 2005

We developed a spacing-tunable comb filter using a sampled fiber Bragg grating (SFBG) by heat-induced multiple phase shifting (MPS). We successfully demonstrated two- and three-fold densifications of channel spacing in an experiment.
Laser-Bessel-Beam-Driven Electron Acceleration
Authors: Li Dazhi , Imasaki Kazuo
Published: September 2005

A vacuum-laser-driven acceleration scheme using a laser Bessel beam is presented. In contrast to the conventional Gaussian beam, the Bessel beam demonstrates diffraction-free propagation, which implies the possibility of extending the effective interaction distance for a laser-electron system. In this method, the Bessel beam is truncated by annular slits to realize a series of nonsuccessive dim regions along the path of laser propagation, where the amplitude of the laser field is reduced, making the electron slightly decelerate as it travels in the decelerating phase. We analyzed the propagation characteristics of the truncated Bessel beam with scalar diffraction theory, and then introduced this approach with careful investigation of a three-stage acceleration model.
The Transient Behavior of the Bistable Nematic Liquid Crystal Cells
Authors: Hsu Jy-Shan , Liang Bau-Jy , Chen Shu-Hsia
Published: September 2005

The transient behaviors switched from homogeneous state in the bistable nematic liquid crystal (BiNem) cell have been studied by simulation. We find two different dynamic relaxation processes of the directors when we apply pulses of the same voltage with 1 and 2 ms durations to the cell. The directors which respond to the 2 ms pulse go directly to the so called twisted state and the relaxation time is short. Those which respond to the 1 ms pulse go through an over twisted process before toward the twisted state and the relaxation time is longer. When the pulse duration is too short, the cell is unable to be switched to the twisted state. The explanation is given via the dynamic behavior of the director near the weak anchoring boundary of the cell.
Optimization on the Thickness of Organic Insulator Layer for Advanced Super-In-Plane Switching Mode Thin-Film-Transistor Liquid Crystal Displays
Authors: Lin Jiunn-Shyong , Yang Kei-Hsiung , Chen Shu-Hsia
Published: September 2005

The growth rate of thin-film-transistor liquid crystal display (TFT-LCD) industries is faster than predicted due to the possible replacement of a cathode-ray tube television (CRT-TV) by a liquid crystal display television (LCD-TV). The in-plane switching (IPS) mode has been known as an excellent technology for realizing a wide viewing angle for LCD-TV, but it has the drawback of a low aperture ratio. An advanced super-IPS (AS-IPS) structure with an organic insulator layer was invented to achieve a high aperture ratio with increasing manufacturing cost. In this paper, we proposed a simple method of analyzing the optimum thickness of the organic insulator layer for AS-IPS. We derived the capacitive coupling ratio (CCR) of the IPS cell and analyzed the delay time of the AS-IPS panel to quantify the crosstalk properties. Furthermore, we also analyzed our electrode structure (AS'-IPS), which not only increases substantially the aperture ratio over that of AS-IPS but also reduces the crosstalk using the same optimized thickness of the organic insulator layer.
The Influence of the Driving Voltage and Ion Concentration on the Lateral Ion Transport in Nematic Liquid Crystal Displays
Authors: Stojmenovik Goran , Neyts Kristiaan , Vermael Stefaan , Verschueren Alwin R. M. , Asselt Rob van
Published: September 2005

Nematic liquid crystal displays (LCDs) contain ions that influence the electrooptical characteristics of the display. A typical super-twisted nematic (STN) display for mobile phone applications becomes darker at a standard driving frequency if it contains many impurity ions. We have discovered that ions can travel in the plane of the glass plates in the absence of a lateral electric field, leading to lateral nonhomogeneity in transmission (dark and bright stripes). In this paper, we present our research on the lateral ion transport dependence on the driving square wave (SQW) amplitude and dc component at a wide range of ion concentrations. The existence of a dc component, a high ion concentration and high SQW amplitudes increase the lateral ion speed.
Concept and Results of New Operation Scheme with Improved Control System for Radio Frequency Heating in JT-60U
Authors: Moriyama Shinichi , Shinozaki Shin-ichi
Published: September 2005

The control system of the RF heating system in JT-60U has been improved with the concept of dispersion processing and by featuring a real-time waveform shaping method. The new dispersion processing system has higher performance and reliability than the old single-processor system before modification. Moreover, improvement of operator role sharing, using the real time waveform shaping has enabled more efficient and smooth operation. In the typical role sharing, a simple rectangular waveform of the RF heating power is set by the experiment operator, and the waveform is reshaped with the parameter set by the RF operator who is familiar with the condition of the RF system at that time. The simple and flexible composition of the new control system will also enable further improvement of hardware to enhance plasma performance and facilitate fusion experiments.
Molecular Beam Epitaxy of Highly Oriented Pentacene Thin Films on an Atomically Flat Sapphire Substrate
Authors: Itaka Kenji , Myojin Norikatsu , Yamashiro Mitsugu , Yamaguchi Jun , Koinuma Hideomi
Published: September 2005

The crystal quality of pentacene thin films was found to be markedly improved by the use of atomically flat sapphire substrates. In general, the crystallinity of the thin film depends strongly on the surface condition of the substrate or the underlying layer. However, there are few reports on the flatness effect on the underlying layer to organic thin films grown on dielectric materials such as SiO2 and Al2O3, where it is necessary to fabricate organic thin films for the practical configuration of bottom-gated organic field-effect transistors. The surface of heat-treated sapphire shows step structures with atomically flat terraces, and is an ideal model of the surface of dielectric layers. The grain size and the X-ray diffraction intensity of a pentacene film deposited on this atomically flat substrate increases markedly in comparison with the films deposited on as-polished sapphires. In addition, the photoconductivity of pentacene films was also improved using atomically flat sapphire substrates. This result suggests that the surface roughness of the substrate and the underlying layer plays a important role in the crystallinity and electrical property of pentacene thin films.
Internal Strain of Self-Assembled InxGa1-xAs Quantum Dots Calculated to Realize Transverse-Magnetic-Mode-Sensitive Interband Optical Transition at Wavelengths of 1.5 µm bands
Authors: Ebe Hiroji , Uetake Ayahito , Akiyama Tomoyuki , Kawaguchi Kenichi , Ekawa Mitsuru , Kuramata Akito , Nakata Yoshiaki , Sugawara Mitsuru , Arakawa Yasuhiko
Published: September 2005

We calculated the interband optical transition energies in self-assembled In
x
Ga1-x
As quantum dots on InP as functions of the strain, composition, and height of dots on the basis of the k·p perturbation theory. We found that a transverse-magnetic (TM)-mode-sensitive optical transition at wavelengths in the range from 1.5 to 1.6 µm is achieved due to the light-hole valence band when the crystal lattice is expanded in the same direction of growth as the in-plane lattice matched to the substrate at x≤0.4, or when the lattice is compressed in the growth direction with the in-plane lattice relaxed at x≥0.6. We propose barrier structures covering the dots in order to realize these conditions, leading to TM-mode-sensitive quantum dots for polarization-independent optical amplifiers.
Recent Advances in X-ray Phase Imaging
Authors: Momose Atsushi
Published: September 2005

Since the middle of the 1990s, X-ray phase imaging including phase tomography has been attracting increasing attention. The advantage of X-ray phase imaging is that an extremely high sensitivity is achieved for weak-absorbing materials, such as biological soft tissues, which generate a poor contrast by conventional methods. Medical and biological imaging is the main target of X-ray phase imaging, and several trials using synchrotron radiation sources and laboratory sources have been made. Measuring and controlling the X-ray phase are also significant for X-ray microscopy with a high spatial resolution, and innovative techniques are attracting intense interest. The progress of X-ray phase imaging is supported by the developments in X-ray sources such as third-generation synchrotron radiation sources, optical elements, and image detectors. This article describes the advantages of using X-ray phase information and reviews various techniques studied for X-ray phase imaging.
Endurance and Data Retention Improvement of Silicon–Oxide–Nitride–Oxide–Silicon Nonvolatile Semiconductor Memory Devices with Partially Bottom-Silicon-Rich Nitride Structure
Authors: Chien Hua-Ching , Wu Kuo-Hong , Chang Jui-Wen , Kao Chin-Hsing , Chen Tung-Sheng
Published: September 2005

A significant reliability improvement in silicon–oxide–nitride–oxide–silicon (SONOS) flash memory devices by band-gap engineering of the nitride layer has been attained. The gradually varied reaction gas flow rate during deposition has generated special nitride films with non uniform composition profiles and band gaps. As a result, SONOS devices with partially Si-rich nitride structures have exhibited superior cycling endurance, radiation hardness, and data retention compared with devices with a uniform standard nitride. The marked improvement can be attributed to the increased charge-trapping/detrapping efficiency of the nitride layer since a significant number of highly accessible trapping levels have been created in the nitride that has a graded band gap. In addition, the deepened barrier heights between the nitride and its surrounding oxides may also reduce undesirable charge-loss probability and assist in charge storage. Because the dimension of flash memory cells is continuously shrinking, the proposed technique will be valuable for mass storage applications.
Stability Enhancement of Polysilicon Thin-Film Transistors Using Stacked Plasma-Enhanced Chemical Vapor Deposited SiO2/SiNx Gate Dielectric
Authors: Choi Byoung-Deog , Kim Won-Sik , So Myeong-Seob , Koo Jae-Bon , Kakkad Ramesh , Mo Yeon-Gon , Kim Sung-Chul
Published: September 2005

The use of a double-layer, plasma-enhanced chemical vapor deposited SiO2/SiN
x
film as a gate dielectric material for polysilicon thin-film transistors was investigated in order to reduce mobile ion contamination and to improve gate oxide integrity degradation. We observed that the interposed silicon nitride film between the gate electrode and the SiO2 gate insulator prevents the incorporation of mobile ions into the SiO2 film, and also increases the breakdown voltage of the gate-insulating film. The mobile ion densities for the double SiO2/SiN
x
and single SiO2 gate dielectrics (no interposed SiN
x
layer between the gate electrode and SiO2 gate insulator) were 1.3 ×1011 and 1.7 ×1012/cm2, respectively. The breakdown fields at the 50% failure points in the Weibull plots for the double and single dielectric cases were 8 and 5 MV/cm, respectively. We conclude that the silicon nitride layer of the double gate insulator film minimizes ion contamination, leading to the enhancement of breakdown characteristics.
New Current–Voltage Model for Surrounding-Gate Metal–Oxide–Semiconductor Field Effect Transistors
Authors: Chiang Te-Kuang
Published: September 2005

On the basis of the current continuity equation and closed-form solutions of Poisson's equation, a new and continuous current–voltage (I–V) model that includes both doped and undoped Si bodies for surrounding-gate metal–oxide–semiconductor field effect transistors (MOSFETs) is developed. The continuous form of the I–V equation represents the entire drain current characteristics including all regions of MOSFET operation: linear, saturation and subthreshold. Compared with conventional charge-sheet approximation, this approach preserves physical volume-inversion phenomena and easily predicts drain current characteristics without assuming an empirical smoothing function for the correctness of piecewise approximation. It is shown that the I–V curves can be generated using this model and agree well with two-dimensional (2D) simulation results over various drain biases. This model gives the exact I–V prediction for surrounding-gate MOSFETs and can be used in SPICE simulation.
New Monte Carlo Simulation Technique for Quasi-Ballistic Transport in Ultrasmall Metal Oxide Semiconductor Field-Effect Transistors
Authors: Natori Kenji , Wada Naoya , Kurusu Takashi
Published: September 2005

A new Monte Carlo simulation technique considering the uncertainty relation and the Pauli principle is proposed for analyzing a quasi-ballistic metal oxide semiconductor field-effect transistor (MOSFET). Instead of the conventional phase space that consists of continuous position and momentum, a discrete phase space represented by a complete basis set of the state vector is employed. The carrier dynamics in the device are analyzed using the Monte Carlo simulation framework, in which a possible transition among numerous probabilistic transitions between these discrete states is selected using random numbers. The technique is applied to a 90 nm MOSFET. Analysis shows how the phonon scattering disturbs the ballistic transport, and yields a result that the backscattered flux due to phonon scattering amounts to 27% of the original carrier flux injected from the source for the device.
Contact-Hole Etching with NH3-Added C5F8 Pulse-Modulated Plasma
Authors: Ooka Masahiro , Yokoyama Shin
Published: September 2005

For plasma etching, an alternative perfluorocarbon (PFC) gas is necessary in order to minimize the effect on global warming. Etching contact holes of sub-0.1-µm size in SiO2 is studied using an etching gas with a small greenhouse effect, cyclic (c-) C5F8 containing various other gases (O2, H2 and NH3). Adding NH3 to pulse-modulated plasma is quite effective for improving the etching characteristics compared with adding O2 or H2. Adding NH3 improves both the hole profile and etching selectivity. The influence of the added NH3 gas was analyzed by optical emission spectroscopy (OES), and the correlation between the flow rate of NH3, the OES results, and the SiO2 etching rate was studied.
Magnesium Diffusion at Dislocation in Wurtzite-Type GaN Crystal
Authors: Harafuji Kenji , Kawamura Katsuyuki
Published: September 2005

The behavior of interstitial Mg atoms at an edge dislocation is studied in the wurtzite-type GaN crystal by molecular dynamics (MD) simulation. Parameters for a two-body interatomic potential are determined by the Hartree–Fock ab initio method. First, an edge dislocation extending to the [0001] direction is generated in an MD basic cell composed of about 11,000 atoms. Second, Mg atoms are placed at substitutional and interstitial positions in the MD basic cell, and the Mg atoms are traced. It is found that the diffusivity of Mg atoms at a dislocation is enhanced along the dislocation. At 1000 K, the diffusivity of interstitial Mg atoms inside the dislocation core is approximately three orders of magnitude larger than that of interstitial Mg atoms located outside the dislocation. The enhanced diffusion along the dislocation originates from unbalanced atomic forces between the Mg atom and surrounding atoms.
Control System for Readout Electronics of Multi-Channel Magnetocardiographs Using High-Temperature DC Superconducting Quantum Interference Devices
Authors: Kandori Akihiko , Suzuki Daisuke , Tsukamoto Akira , Kumagai Yukio , Miyashita Tsuyoshi , Ogata Kuniomi , Seki Yusuke , Yokosawa Koichi , Tsukada Keiji
Published: September 2005

We aimed to develop a control system for multichannel magnetocardiography (MCG) based on a high-temperature DC superconducting quantum interference device (high-T
c SQUID). To create this system, we used one oscillator as an AC bias controller to operate a multichannel high-T
c SQUID. To optimize the SQUID parameters (such as the AC bias, offset voltage), two new control sequences based on a cross-correlation method and a fast Fourier transform method were developed. Using the AC bias controller and the sequences, the typical white noise level of the SQUID was about 50–60 fT Hz-1/2 around 100 Hz. Multichannel MCG signals were detected clearly in the system with the SQUIDs. We conclude that our control system with one oscillator and new protocols can reliably operate a multichannel SQUID.
Laser Interference Lithography with Highly Accurate Interferometric Alignment
Authors: Soest Frank J. van , Wolferen Henk A. G. M. van , Hoekstra Hugo J. W. M. , Ridder René M. de , Wörhoff Kerstin , Lambeck Paul V.
Published: September 2005

It is shown experimentally that in laser interference lithography, by using a reference grating, respective grating layers can be positioned with high relative accuracy. A 0.001° angular and a few nanometers lateral resolution have been demonstrated.
Experimental and Numerical Study of Charge-Pump Pixel Addressing for Organic Light-Emitting Diode Displays
Authors: Seo Jong-Wook , Kim Han Byul , Pyun Chang Soo
Published: September 2005

A charge-pump (CP) pixel addressing method for an organic light-emitting diode (OLED) display panel is shown to be feasible by implementing pixel arrays of both OLEDs and semiconductor light-emitting diodes (LEDs). It is also shown that the light output from the CP-OLED can be made to last for the entire panel scanning period and that the crosstalk between pixels can be minimized by a proper choice of drive signal waveforms. A SPICE circuit model is developed, and a pn-junction model is found to be effective in the numerical simulation of CP-OLED display panels. It is also found that a high contrast ratio and a high luminance level can be achieved using the new pixel addressing method.
Dual Domain Effect on a Rubbing Mura in Liquid Crystal Displays Associated with In-Plane Rotation of LC Director
Authors: Oh Sang Min , Eom Tae Young , Kim Seung Jae , Lee Seung Hee , Kim Hyang Yul , Lim Young Jin
Published: September 2005

The liquid crystal (LC) modes, in-plane switching (IPS) and fringe-field switching (FFS), associated with a transition from a homogenously aligned to twist deformation require rubbing process. In both devices, 1° of misalignment in azimuthal direction could cause voltage–dependent transmittance (V–T) to be different from that in a normal area and consequently results in a rubbing mura. According to our studies, dual domain structure of the FFS and IPS modes could reduce such a V–T difference dependent on the position although 1° of misalignment exists since the LC directors rotate clockwise and anticlockwise.
Effect of Horizontal Electric Field Generated by Data Signal on Disclination Lines near Pixel Edge in Fringe Field Switching Mode
Authors: Kim Mi Sook , Seen Seung Min , Jeong Youn Hak , Kim Hyang Yul , Kim Seo Yoon , Lim Young Jin , Lee Seung Hee
Published: September 2005

We have studied the dynamic stability of a liquid crystal (LC) in an adjacent active region near the edge of a pixel slit according to the horizontal electric field generated by the data signal for the fringe field switching (FFS) mode. The horizontal component of a fringe electric field becomes strong as the distance between the common electrode and the data bus line decreases. Therefore, the disclination lines (DLs), which are formed near the pixel edge, barely intrude an active region. Moreover, the LC director existing in this region becomes stable and has a large twist angle. This indicates that the LC dynamic stability near the pixel edge is markedly affected by the horizontal electric field of a strong data signal.
Copper Plating Method on Flat Surface for High Frequency Signal Transfer
Authors: Hontake Koichi , Wakizaka Yasuhiro , Furuya Akihiko , Uchida Daisuke , Kuribayashi Koichiro , Noda Tomoko , Sugimura Masahiko , Chikuma Mitsuyasu , Toki Sotaro , Sasaki Jun , Hagiwara Muneaki , Nakada Akira , Kubota Hiroshi
Published: September 2005

A copper plating process for printed wiring boards operating in the GHz frequency range has been developed that improves the adhesion strength between the copper interconnects and the resin substrate by using an imidazole compound to form coordinate bonds. The coordinate bonds are prepared by impregnating the resin substrate with an aqueous solution of amino-group-containing imidazole (AI). The adhesion strength is measured by a tensile test with various concentrations of AI solution and different treatment times of impregnation. As a result, the highest adhesion strength of 4.2–5.1 N·cm-1 can be obtained on the entire surface of a 340×340 mm2 substrate, where the flatness is down to 58.7 nm. This result is due to the optimization of the impregnating condition for AI and of the removal condition for weak boundary layers. The signal transmission characteristics of the interconnects on the substrates fabricated by this processes are compared with the conventional process by S
21 parameter extraction in the GHz frequency range. The transmission characteristics of this process are markedly improved compared with those of conventional processes.
Effect of RF Power on Physical Properties of MgTiO3 Films by RF Magnetron Sputtering
Authors: Huang Cheng-Liang , Chen Yuan-Bin
Published: September 2005

Physical properties of rf-sputtered crystalline MgTiO3 thin films deposited on n-type Si(100) substrates at different rf powers have been investigated. These films were fabricated at 400°C by choosing different RF powers (from 100 to 400 W) at a substrate temperature of 400°C which is much lower than the bulk sintering temperature. X-ray diffraction (XRD) analysis showed that the deposited films exhibited a polycrystalline microstructure. The grain size of the films increased with increasing RF power. The electrical properties were measured using C–V and I–V measurements on metal-insulator-semiconductor (MIS) capacitor structures. At an RF power of 400 W and a substrate temperature of 400°C, a dielectric constant of 16.2 ( f =10 MHz), a leakage current density of 2.03 ×10-9 A/mm2 and a dissipation factor of 0.041 were obtained.
Beamwidth Control in Parametric Acoustic Array
Authors: Yang Jun , Tan Khim-Sia , Gan Woon-Seng , Er Meng-Hwa , Yan Yong-Hong
Published: September 2005

Directional sound can be generated by amplitude-modulating the ultrasound carrier wave with an audio signal and then transmitting it from an array system. On the basis of the analysis of its radiation pattern, an algorithm using delay-and-sum beamforming is proposed to control the beamwidth and sidelobe of demodulated audible sound. Simulation results show that enhanced performance in terms of sidelobe level can be achieved by using the Chebyshev weighting function, compared with the beamforming algorithm without shading.
Observation of Amorphous Recording Marks Using Reflection-Mode Near-Field Scanning Optical Microscope Supported by Optical Interference Method
Authors: Sakai Masaru , Mononobe Shuji , Yusu Keiichiro , Tadokoro Toshiyasu , Saiki Toshiharu
Published: September 2005

A signal enhancing technique for a reflection-mode near-field scanning optical microscope (NSOM) is proposed. Optical interference between the signal light, from an aperture at the tip of a tapered optical fiber, and the reflected light, from a metallic coating around the aperture, enhances the signal intensity. We used a rewritable high-definition digital versatile disc (HD DVD) with dual recording layers as a sample medium, and demonstrated observation of amorphous recording marks on the semitransparent (the first) recording layer. In spite of low optical contrast between the crystal region and the amorphous region on this layer, we successfully observed recording marks with good contrast.
Electrical and Thermal Stability Characteristics of HfCN Films as Metal Gate-Electrode Synthesized by Metalorganic Chemical Vapor Deposition
Authors: Wang Wenwu , Nabatame Toshihide , Haneji Nobuo , Shimogaki Yukihiro
Published: September 2005

Hafnium carbonitride (HfCN) films were prepared by metalorganic chemical vapor deposition (MOCVD) using Hf[N(C2H5)2]4 (TDEAHf) precursor. The electrical and thermal stability characteristics of the CVD-HfCN films as a metal gate electrode were studied for the first time for the MOS device application. As a result, the effective work function of HfCN (ΦHfCN) on SiO2 and HfO2 dielectrics were extracted from the C–V measurements of each MOS stack with various equivalent oxide thickness (EOT) to be about 4.54 and 4.45 eV, respectively. Especially, for the HfCN/SiO2/Si stack, after rapid thermal annealing (RTA) at high temperature, the EOT shows negligible change; while the ΦHfCN increased gradually to be about 5.08 eV at 900°C.
Enhancement of Formation in Boron–Carbon–Nitrogen Nanotubes by Plasma Rotating Electrode Process
Authors: Kim Chang Su , Choi Sang Hun , Kim Woo Jin , Jo Sung Jin , Lee Se Jong , Song Kie Moon , Baik Hong Koo
Published: September 2005

We investigated the effect of anode rotation on the nucleation and growth of B–C–N nanotubes by the plasma rotating electrode process (PREP). With rotation of the anode and/or increase in metal concentration, the number and length of nanotubes were increased, that is, the yield of B–C–N nanotubes was increased. This result is related to the improvement of discharge characteristics by rotating the anode and/or the enhanced catalytic effect of metal species.
Capacitance Measurement in Organic Thin-Film Device with Internal Charge Separation Zone
Authors: Terai Masaya , Fujita Katsuhiko , Tsutsui Tetsuo
Published: September 2005

To verify the concept of electric-field-assisted bipolar charge spouting in organic thin films, model devices with an internal charge separation (ICS) zone were fabricated. A double-insulation-type organic thin-film device, indium–tin–oxide (ITO)/poly-chloro- p-xylylene (PCPX)/tris(8-quinolinolato)aluminum(III) (Alq3)/Mg-doped Alq3/V2O5/N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD)/PCPX/Al (device with an ICS zone), and four devices with similar structures without the ICS zone were fabricated. The capacitance of the devices under positive and negative applied biases was measured. The device with the ICS zone showed a clear capacitance increase when the bias condition met the electric-field-assisted bipolar charge separation.
Non-equilibrium Phenomenon between Electron and Lattice Systems Induced by the Peltier Effect
Authors: Iwasaki Hideo , Hori Hidenobu , Sasaki Shosuke
Published: September 2005

Temperature distributions of the electron and lattice systems induced by the Peltier effect have been precisely measured by improved Harman method, where the temperature differences (ΔT
el and ΔT
la) have been independently evaluated for several terminal lengths (L
V) in thermoelectric materials (Bi,Sb)2Te3. Both temperature distributions have different behaviors in the stationary state, that is, the L
V dependences of ΔT
el and ΔT
la show positive and negative curvatures, respectively. It is also indicated that the temperature difference has a linear relation to L
V in the whole system and the observed non-equilibrium phenomenon is consistent with a law of the conservation of heat quantity.
Characterization of Planar Semipolar Gallium Nitride Films on Spinel Substrates
Authors: Baker Troy J. , Haskell Benjamin A. , Wu Feng , Fini Paul T. , Speck James S. , Nakamura Shuji
Published: September 2005

Specular, planar semipolar gallium nitride films were grown by hydride vapor phase epitaxy. This is the first report of high quality semipolar GaN films that could be used for device growth. Planar films of (10-1-1)GaN have been grown on (100)MgAl2O4 spinel, and planar films of (10-1-3)GaN have been grown on (110)MgAl2O4 spinel. The in-plane epitaxial relationship for (10-1-1)GaN on (100) spinel was [10-1-2]GaN ∥[011]spinel and [1-210]GaN ∥[0-11]spinel. The in-plane epitaxial relationship for (10-1-3)GaN on (110) spinel was [30-3-2]GaN ∥[001]spinel and [1-210]GaN ∥[-110]spinel.
Effects of Reflective Coatings on Performance of Divergence-Narrowed External-Cavity Laser-Diode Arrays
Authors: Zheng Yujin , Miyajima Hirofumi , Suzuki Hideki , Kan Hirofumi
Published: September 2005

This study was conducted to experimentally investigate how reflective coatings on the front facets of laser-diode arrays (LDAs) affect the performance of external-cavity LDAs, devices that yield divergence-narrowed emission. We compared the performance of two external-cavity LDAs equipped with front facets coated with different reflective coatings (with a low or high reflectivity). Our results confirm that a low reflectivity yields a superior performance in a divergence-narrowed external-cavity LDA. At a high drive current of 39.9 A, the divergence angle of an LDA with a low-reflectivity coating of 3% was suppressed from 8.4 to 1.2° at an available output power of 22.3 W.
Control of Epitaxial Growth Orientation and Anisotropic Thermoelectric Properties of Misfit-Type Ca3Co4O9 Thin Films
Authors: Sakai Akihiro , Kanno Tsutomu , Yotsuhashi Satoshi , Odagawa Akihiro , Adachi Hideaki
Published: September 2005

We have investigated the control of crystal orientation in misfit-type layered cobaltite Ca3Co4O9 thin films by rf-planar magnetron sputtering and succeeded in growing epitaxial films with c-axis, a-axis and b-axis orientations normal to the substrate. Anisotropic transport properties (parallel to the CoO2 layers and perpendicular to the CoO2 layers) were measured using the b-axis-oriented epitaxial films with a layered structure perpendicular to the substrate surface. The resistivity parallel to the CoO2 layers (ρ
a
) is about 8 mΩ cm at room temperature while that perpendicular to the CoO2 layers (ρ
c
) is about 300 mΩ cm; the anisotropy is estimated to be about 40. Thermoelectric anisotropy is not considerably pronounced; the parallel Seebeck coefficient S

a
is measured to be 110 µV/K and the perpendicular S

c
is 40 µV/K at room temperature.
5×5 cm2 GaAs and GaInAs Solar Cells with High Conversion Efficiency
Authors: Yamada Takashi , Moto Akihiro , Iguchi Yasuhiro , Takahashi Mitsuo , Tanaka So , Tanabe Tatsuya , Takagishi Shigenori
Published: September 2005

We fabricated GaAs and GaInAs solar cells with a large cell area of 5×5 cm2 as the first step toward their practical use. The 5×5 cm2 cells showed high conversion efficiencies equivalent to those of 1×1 cm2 cells owing to both a good uniformity of epitaxial film characteristics in a 3-inch wafer and the reduction of the series resistance of grid electrodes. Moreover, a higher conversion efficiency of 26.0% under 1-sun air-mass 1.5 global conditions was achieved for the 5×5 cm2 GaAs cell by optimizing the antireflection coating. This is the highest efficiency among GaAs cells ever reported. The 5×5 cm2 GaInAs cell showed an efficiency of 4.2% as the bottom cell under a GaAs top cell. Therefore, a conversion efficiency of more than 30% can be expected for the 5×5 cm2 GaAs/GaInAs mechanically stacked tandem cell.
Control of Glut1 promoter activity under basal conditions and in response to hyperosmolarity: role of Sp1
Authors: Hwang Daw-Yang , Ismail-Beigi Faramarz
Published: September 2005

We previously identified (Hwang DY and Ismail-Beigi F. Am J Physiol Cell Physiol 281: C1365–C1372, 2001) a 44-bp GC-rich segment of the rat proximal glucose transporter (Glut)1 promoter, located at −104 to −61, as necessary for basal transcription of the Glut1 gene. Using deletion and mutational analysis and expression of transfected reporter constructs, we report in the present study that mutation of the Sp1 site located within this segment of the promoter leads to a marked (∼4-fold) decrease in basal promoter activity. Double mutations located in the Sp1 site and in a second downstream GC-rich region (−71 to −51) did not cause a further decrease in promoter activity. Gel shift and supershift assays verified the importance of the Sp1 site. Exposure of cells to trichostatin A resulted in increased expression of the endogenous Glut1 as well as the transfected wild-type construct. Finally, the presence of the Sp1 site was found to be essential for the positive response of the promoter to hyperosmolarity. We conclude that the consensus Sp1 site located in the rat proximal Glut1 promoter is necessary and sufficient for basal expression of the Glut1 gene, as well as for its response to hyperosmolarity.
Role of the renal nerves in blood pressure in male and female SHR
Authors: Iliescu Radu , Yanes Licy L. , Bell William , Dwyer Terry , Baltatu Ovidiu C. , Reckelhoff Jane F.
Published: September 2005

Female spontaneously hypertensive rats (SHR) have lower blood pressures than males. The renin-angiotensin system plays an important role in the sexual dimorphism of blood pressure in SHR. The sympathetic nervous system can stimulate renin release, and, therefore, the present study was performed to determine whether the renal sympathetic nerves play a role in the sexual dimorphism of blood pressure in SHR. Male and female SHR underwent bilateral kidney denervation or sham surgery, and, 2 wk later, mean arterial pressure (MAP) and pulse interval were recorded, and baroreflex sensitivity (BRS) was measured by the sequence technique. Left ventricle index (LVI) was also calculated. MAP was higher in sham-operated males than females (182 ± 5 vs. 169 ± 4 mmHg; P < 0.01), but, despite the higher MAP in males, LVI was significantly greater in female rats. BRS was not different between sham-operated male and female SHR. Following bilateral renal denervation, MAP was decreased by a similar percentage (8–10%) in males (169 ± 2 mmHg) and females (152 ± 3 mmHg), whereas LVI was reduced only in female SHR. BRS was not altered by renal denervation in either sex. These data indicate that renal nerves play a role in the control of blood pressure in SHR independent of sex, but do not play a role in mediating the sex differences in blood pressure.
Hyperthermia-Induced Proteasome Inhibition and Loss of Androgen Receptor Expression in Human Prostate Cancer Cells
Authors: Pajonk Frank , van Ophoven Arndt , McBride William H.
Published: September 2005

Prostate cancer is the second leading cause of death in men in western countries and is usually treated by surgery and/or radiotherapy. More recently, hyperthermia has been introduced into clinical trials investigating a possible effect in the first-line treatment of prostate cancer. However, the molecular mechanisms of hyperthermia are not completely understood. In this study, we investigated the effects of hyperthermia on proteasome function and its significance for signal transduction, cell death and androgen receptor (AR) expression in PC-3, LnCaP, and DU-145 human and TRAMP-C2 murine prostate cancer cells. Hyperthermia caused apoptosis and radiosensitization and decreased 26S proteasome activity in all three human cell lines to about 40% of untreated control cells. 20S proteasome activity was not affected by heat. Heat treatment inhibited constitutive and radiation-induced activation of nuclear factor κB caused by stabilization of IκB. Although stabilization of AR by proteasome inhibitors has been reported previously, AR protein levels in LnCaP cells decreased dramatically after heat. Our data suggest that inhibition of proteasome function and dependent signal transduction pathways might be a major molecular mechanisms of heat-induced apoptosis and radiosensitization. Hyperthermia abrogates AR expression in androgen-dependent cells and might thus promote malignant progression of prostate cancer.
Coexpression of Cyclooxygenases (COX-1, COX-2) and Vascular Endothelial Growth Factors (VEGF-A, VEGF-C) in Esophageal Adenocarcinoma
Authors: von Rahden Burkhard H.A. , Stein Hubert J. , Pühringer Franziska , Koch Ina , Langer Rupert , Piontek Guido , Siewert J. Rüdiger , Höfler Heinz , Sarbia Mario
Published: September 2005

Cyclooxygenases (COX), especially COX-2, are considered to be involved in carcinogenesis. Our study was initiated to test whether expression of COX isoforms (COX-1 and COX-2) is linked to expression of potent inducers of angiogenesis [vascular endothelial growth factor (VEGF)-A] and lymphangiogenesis (VEGF-C) in esophageal adenocarcinoma. One hundred twenty-three esophageal adenocarcinomas were investigated by means of quantitative reverse transcription-PCR for expression of COX-1, COX-2, VEGF-A, and VEGF-C. Additionally, COX-2 protein expression was determined using immunohistochemistry. Three esophageal cancer cell lines (OE-33, OSC-1, and OSC-2) were treated with COX-inhibiting substances (diclofenac, rofecoxib, and SC-560) and the effect on expression of the four genes was determined. COX-2 protein expression was found in all carcinomas under analysis. RNA expression levels of COX-1 and COX-2 varied markedly in carcinoma tissues and correlated significantly with each other (P < 0.001, r = 0.726). Furthermore, COX expression correlated with expression of VEGF-A (COX-1: P < 0.001, r = 0.753; COX-2: P < 0.001, r = 0.764) and VEGF-C (COX-1: P < 0.001, r = 0.778; COX-2: P < 0.001; r = 0.613). Exposure of esophageal cancer cell lines OE-33, OSC-1, and OSC-2 with three COX-inhibiting substances (diclofenac, rofecoxib, and SC-560) resulted in significantly reduced expression of VEGF-A and VEGF-C. In conclusion, our data suggest that both COX isoforms may be involved in the pathogenesis of esophageal adenocarcinoma, as they are linked to the expression of important modulators of angiogenesis (VEGF-A) and lymphangiogenesis (VEGF-C).