bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Plane Orientation and Annealing Behavior of Rutile TiO2 Films on MgO Substrate Prepared by Inductively Coupled Plasma-Assisted Sputtering
Authors: Okimura Kunio , Furumi Takahiro
Published: July 2005

In-plane orientation and annealing behavior of Rutile TiO2 films grown on MgO (100) substrates by means of inductively coupled plasma-assisted sputtering were investigated. We deposited TiO2 films on relatively low temperature (≦400°C) MgO substrates in Ar–O2 mixture gases. Several films were annealed in atmospheric O2 at 800°C for 60 min. X-ray φ scan measurements and AFM images revealed that rutile TiO2 film grows on MgO (100) substrate with two orientations of TiO2 (110)[001]∥MgO (100)[011] and TiO2 (110)[001]∥MgO (100)[011]. Post annealing in atmospheric O2 at 800°C improved the crystalline preference of TiO2 film, however, formation of MgTiO3 interface layer was clearly shown by cross sectional TEM image and XPS depth analysis. Values of refractive index and band gap energy were evaluated from optical characteristics of the films. High refractive index of 2.65 at wavelength of 500 nm in as-deposited TiO2 film degraded to 2.0 in annealed film due to the formation of MgTiO3 interface layer. Through this study, we offer stable rutile (110) surface and a formation route of MgTiO3 dielectric layer.
Effects of Process Parameters on the Deposition Rate, Hardness, and Corrosion Resistance of Tungsten Carbide Coatings Deposited by Reactive Sputtering
Authors: Park Yunkyu , Lim Jongmin , Lee Chongmu
Published: July 2005

The reactive sputter deposition of tungsten carbide (WC
x
) films as an alternative to chromium electroplating was studied. The effects of rf power, pressure, sputtering gas composition, and substrate temperature on the deposition rate of the WC
x
coatings were investigated. The effects of rf power and sputtering gas composition on the hardness and corrosion resistance of the WC
x
coatings were also investigated. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) analyses were performed to determine the structures and compositions of the films, respectively. The hardnesses of the films were measured using a nanoindenter. The microstructures of the films were observed by scanning electron microscopy. The corrosion resistances of the films were evaluated using a salt-spray test. The deposition rate of the films was proportional to rf power and inversely proportional to the CH4 content of the sputtering gas. The deposition rate increased linearly with increasing chamber pressure. The hardness of the WC
x
coatings increased as rf power increased. The highest hardness was obtained at a CH4 concentration of 10 vol.% in the sputtering gas. The hardness of the WC
x
film deposited under optimal conditions was much higher than that of the electroplated chromium film, although the corrosion resistance of the former was slightly lower than that of the latter.
Effect of the Surface Temperature on Formation of Low-Temperature Phase in Magnetron-Sputtered Chromium Films
Authors: Shaginyan Leonid R. , Han Jeon Geon , Britun Nikolay V.
Published: July 2005

The existence of a low-temperature (LT) chromium phase with the primitive cubic lattice in chromium films is questionable. We revealed that the main condition necessary for LT phase formation in magnetron sputtered Cr films is the deposition of the film from low-energy atomic flux, which is accomplished during deposition at a high working gas pressure. The films deposited from high-energy atomic flux at a low gas pressure crystallized in the ordinary bcc phase independently of the substrate temperature. This effect is explained by assuming the existence of a “hot” layer on the growth surface whose temperature can be noticeably higher than the substrate temperature.
Properties of Thermal Gadolinium Oxide Films on Silicon
Authors: Ko Hong-Hsi , Chang Liann-Be , Jeng Ming-Jer , Kuei Ping-Yu , Horng Kuo-Yang
Published: July 2005

The formation and electrical characteristics of thermal gadolinium (Gd) oxide films were investigated. A good uniform interface formed by proper treatment was observed by transmission electron microscopy (TEM) examination. The dielectric constant of the thermal Gd oxide films was approximately 10 from capacitance–voltage measurements. The X-ray diffraction (XRD) pattern of the thermal Gd oxide (Gd2O3) films showed that they had a cubic structure. The Gd oxides that were oxidized at higher temperatures exhibited smaller grain boundaries than those oxidized at lower temperatures. The grain boundary size of the Gd oxides significantly affects the leakage property. A good Gd oxide quality can be obtained when the thermal oxidation temperature is above 900°C.
Amplitude Dependence of the Lateral-Vibration Wear Test for Perpendicular Recording Magnetic Disks Treated by Heat Curing
Authors: Miyake Shojiro , Wakatsuki Yukihiko , Wang Mei , Matsunuma Satoshi
Published: July 2005

The tribological characteristics of perfluoropolyether (PFPE) and heat-treated PFPE lubricant films deposited on magnetic thin diamond-like carbon (DLC) film-coated disks by dip coating were studied using lateral modulation frictional force microscopy (LM-FFM). The topography and microstructural properties of the DLC film disk before PFPE lubricant dip coating were investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM) in the dynamic force modulation (DFM) and frictional force modulation (FFM) modes. The TEM and AFM images show valleys and fine spaces formed between grain boundaries. It is possible that free lubricants reserved in these valleys and spaces during dip coating replenished the surface as a result of tip sliding. In wear tests, the friction properties of the PFPE-DLC disk without heat curing were improved due to the supply of lubricant.
Growth and Characterization of ZnO Film on Sapphire by the Helicon Wave Oxygen-Plasma-Assisted Evaporation Process
Authors: Park Sun-Hong , Park Tae-Hee , Kim Kyoung-Bo , Kwon Kwang-Woo , Park Chan-Hyuk , Kim Ki-Sung , Han Sang-Wook , Kim Seon-Hyo
Published: July 2005

The growth of ZnO films on [0001] sapphire substrates was studied using the high-density helicon wave oxygen-plasma (>1011/cm2)-assisted evaporation process. The crystallinity and optical properties of the ZnO films fabricated with and without a grounded grid installed at the end of the plasma source were studied by X-ray diffraction (XRD) analysis, atomic force microscopy (AFM) and photoluminescence (PL) measurements. XRD measurements showed that both samples were highly oriented films along the c-axis perpendicular to the substrate surface. The full widths at half maximum of the θ-rocking curve at (0002) diffraction were 0.53 and 0.63° for the ZnO films grown with and without the grid, respectively. AFM images show that the rms surface roughness of the films grown with the grid is ∼4 times smaller than that without the grid. These indicate that the quality of the ZnO films was considerably improved by adopting the grounded grid. The PL spectra of the ZnO films deposited without the grid showed the prominent deep-level emissions that were not observed from the films grown with the grid. The deep-level emissions might be attributed to the impurities and native defects in the films. These strongly suggest that the grounded grid effectively eliminated the charged ionic species, in the plasma, that can deteriorate the crystalline structure of the ZnO films.
Electron-Induced Modification of Ethylene Molecules Chemisorbed on Si(100) Surface
Authors: Hasegawa Takahide , Mochiji Kozo , Imai Hidenori , Mitamura Toru
Published: July 2005

The effects electron-beam irradiation had on ethylene-chemisorbed Si(100)-2×1 surfaces were investigated. We used a scanning tunneling microscope as an electron-beam source as well as for structural analysis. In the scanning tunneling microscope (STM) image taken of the surface after electron-beam irradiation, two kinds of small and large bright dots appeared, while numerous ethylene molecules had been removed by electron-stimulated desorption. The small bright dots could only be observed at very low electron doses. In contrast, the large bright dots once formed were resistant to successive electron irradiation. The large bright dots could be identified as cyclobutane chemisorbed on Si(100)-2×1. The small bright dots were intermediate species that remained after losing four hydrogen-atoms due to electron irradiation. These species easily react with desorbed ethylenes to form cyclobutanes.
Use of Dielectrophoresis in a High-Yield Fabrication of a Carbon Nanotube Tip
Authors: Park June-Ki , Kim Ji-Eun , Han Chang-Soo
Published: July 2005

This paper reports on the development of an atomic force microscope (AFM) tip with single multiwalled carbon nanotube (MWNT). We used an ac electric field, which causes dielectrophoresis (DEP), to align and deposit single MWNT on a metal-coated AFM tip. By dropping an MWNT solution and applying an electric field between the AFM tip and the electrode, we were able to directly assemble one of MWNTs that were dispersed in the diluted solution on the apex of the AFM tip. We investigated the experimental conditions under which the aligning angle of the CNT to the tip's axis varied according to changes in the angle of alignment between the tip and the electrode. We found the experimental condition of 75% success rate to fabricate CNT tips, and we show how the CNT tip compares with a conventional silicon tip with respect to the imaging of 15 nm gold particles.
Photoexcitation Process Leading to Modification on Poly(tetrafluoroethylene) Surface by Irradiation of Synchrotron Radiation in Soft X-ray Region
Authors: Kanda Kazuhiro , Kato Yuri , Ideta Tomoya , Haruyama Yuichi , Ishigaki Hiroyuki , Matsui Shinji
Published: July 2005

Photoexcitation process leading to a variation in the wettability of a poly(tetrafluoroethylene) (PTFE) surface induced by synchrotron radiation (SR) exposure in the soft X-ray region was investigated. It was found that two types of photoexcitation, that is, the formations of a hydrophobic surface and a hydrophilic surface, proceed on the PTFE surface with the exposure to SR. The formation rate of the hydrophobic surface strongly depended on substrate temperature.
Experimental and Theoretical Investigations of Anode Double Layer
Authors: Gurlui Silviu , Agop Marcel , Strat Mitachi , Strat Georgeta , Bācāiţā Simona
Published: July 2005

The anodic double layer is studied by electrical methods. Irradiating this layer with an optical electromagnetic radiation, resulted in current intensity oscillations and also an increase in their amplitude. A theoretical model is described on the basis of a nonlinear diffusion equation, and both double layer diameter and characteristic oscillation time were calculated. Theoretical results are in agreement with experimental results.
Effects of Annealing Conditions on the Crystallization and Grain Growth of Metastable Ge2Sb2Te5
Authors: Park Yu Jin , Lee Jeong Yong , Youm Min Soo , Kim Yong Tae
Published: July 2005

The Ge2Sb2Te5 thin films deposited by a sputtering method on a SiO2/Si substrate were annealed and subjected to transmission electron microscopy in order to investigate the crystallization and growth of the metastable Ge2Sb2Te5. The metastable Ge2Sb2Te5 was initially crystallized with 10-nm-sized grains and its sheet resistance was still as high as in the amorphous state. Sheet resistance was abruptly decreased at the grain growth stage after the crystallization.
Microwave Reflectometry of Turbulence Spectrum in Tokamak Plasmas
Authors: Bruskin Leonid G. , Mase Atsushi
Published: July 2005

The recently proposed method of plasma turbulence spectrum measurements in tokamaks by means of conventional microwave reflectometry is extended to the case of arbitrary density profiles. The localization property and sensitivity of the method to the microwave scattering by fluctuations far from the cut-off layer is studied, with a conclusion that, depending on the turbulence spectrum and amplitude, such a scattering can deteriorate the results of spectrum reconstruction. However, if turbulence spectrum parameters do not reveal drastic radial variations, the cumulative effect of fluctuations far from the reflection area is not significant. In such a case the reconstructed poloidal wavenumber spectrum of density fluctuations is well localized near the cut-off layer. The studied cases correspond to the geometry and plasma parameters on the JT-60U tokamak.
Rapid and Precise Measurement System for Ultrasonic Velocity by Pulse Correlation Method Designed for Chemical Analysis
Authors: Hosoda Maiko , Takagi Kenshiro , Ogawa Hideo , Nomura Hiroyasu , Sakai Keiji
Published: July 2005

We developed an automatic measurement system for ultrasonic velocity in the megahertz region particularly designed for materials science. The ultrasonic pulse method is fully supported by digital equipment and the correlation function of the 1st and 2nd pulse echoes is numerically obtained from the ultrasonic velocity precisely determined to a relative accuracy of 10-6. An ultrasonic corner reflector is also employed to realize the high reproducibility of the measurement without adjusting the parallelism of the countering transducer and reflector. The performance of the system is examined by determining the concentration dependence of sound velocity in an electrolyte solution in a dilute range.
Two-Dimensional Birefringence Profiling of Optical Wafers by Differential Phase Retardation Method
Authors: Shichijyo Shiro , Fujii Shigeharu , Uchida Masao , Yamada Kazuhiro
Published: July 2005

We have proposed a new method of observing two-dimensional birefringence profiles in optical crystal wafers irrespective of physical thickness distribution by differentiating phase retardations of two orthogonal polarizations. The birefringence profiling of LiNbO3 wafers of 125 mm diameter has been demonstrated and inhomogeneous structures with a small birefringence of approximately 1×10-5 have been visualized successfully. It is suitable for not only material analysis in research but also a rapid non-destructive inspection of wafers in production lines.
Scanning Laser Microscope Able to Detect the Refraction of the Laser Beam
Authors: Mitsui Takahisa
Published: July 2005

We have developed a scanning laser microscope system that can measure the spatial inhomogeneity of the refractive index using the laser beam refracted by the sample. Using this microscope, we can observe samples which are nearly transparent, such as live cells, without any use of dyes. Furthermore, we have visualized the Brownian motion of cell structures by detecting random fluctuations in the photoelectric current. This allows us to understand the rigidity of cell structures and the mobility within them.
Composition and Crystal Phase Control of Chemical-Vapor-Deposited Pb(Zrx,Ti1-x)O3 Films on Various Oxide Electrodes with Reactants Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4 and O2
Authors: Cheng Wei Yuan , Hong Lu Sheng
Published: July 2005

The film-composition-determining path of lead zirconate titanate chemical vapor deposition (PZT-CVD) in a cold-wall reactor operated at 773 K was studied using Pb(C2H5)4, Zr(O-t-C4H9)4, Ti(O-i-C3H7)4, and O2 as the reactants. The differences in composition and crystalline properties of PZT films grown on various oxide substrate surfaces under the same reaction conditions revealed that a heterogeneous reaction between Pb(C2H5)4 and O2 to form PbO as an intermediate plays a decisive role in determining the PZT composition in this multi-component CVD system. To explain these substrate-dependent differences in growth behavior, a reaction model was then developed that utilizes the electronegativity difference of O between the PbO and the oxide substrate as the affinity index for chemisorption of Pb(C2H5)4. This model explains well why PZT grown on IrO2 (with a strong affinity) tends to be Pb-rich in composition but Pb-deficient on (La,Sr)CoO3 (with a weak affinity).
Microwave Local Oscillator for a Cesium Frequency Standard Synthesized from a Cryogenic Sapphire Oscillator
Authors: Watabe Ken-ichi , Hartnett John G. , Santarelli Giorgio , Yanagimachi Shinya , Ikegami Takeshi , Ohshima Shin-ichi
Published: July 2005

A synthesized microwave local oscillator for a cesium atomic frequency standard has been implemented using an ultra-stable oscillator. The oscillator was based on a high Q-factor cryogenic-sapphire-resonator cooled with liquid helium which operates on a Whispering Gallery mode. The cesium hyperfine transition frequency of 9.192 GHz was synthesized from the 10.812 GHz oscillation frequency, chosen because the corresponding mode had the best frequency stability. When compared with a hydrogen maser reference the local oscillator exhibited a fractional frequency stability of 6×10-15 for integration times of 600 to 1200 s at 9.192 GHz, limited only by the cryogenic sapphire oscillator.
Double-Type Photocoupler Negative Feedback Circuit for Very Low Level DC Current Amplifier
Authors: Higa Hiroki , Higashionna Takashi , Maehama Takehiro , Nakamura Ikuo
Published: July 2005

To obtain fast response in a very low level dc current amplifier, the amplifier using a single-type photocoupler negative feedback circuit has been developed; however, it has an offset drift problem because of the electrical property of the photocoupler. In this study, we proposed a very low level dc current amplifier using a double-type photocoupler negative feedback circuit that has two functional parts, that is, a negative feedback part and an offset controller. The experimental results show that the response speed of this amplifier is as high as that of the amplifier using the single-type circuit, and that the offset voltage drift of the amplifier using the double-type circuit is markedly improved.
Optimum Target Position of Ion Production in Ultrashort-Pulse Laser Interaction with Foil Targets under the Existence of Prepulses
Authors: Wada Yoshio
Published: July 2005

It was found that ion production during ultrashort-pulse laser interaction with foil targets is most efficient when the target is positioned behind the waist of the laser, and if the main laser pulse is accompanied by prepulses that evaporate the target. The maximum proton energy was 1.2 MeV when the target was positioned 0.3 mm behind the waist, while it was 0.25 MeV at the waist. A model is proposed in which a prepulse ablates the surface of the target. The resultant neutral gas guides the head of the main pulse caused by the Kerr effect while it is ionized, so the ion generation is more efficient than that without a prepulse.
Simple Ultraviolet Short-Pulse Intensity Diagnostic Method Using Atmosphere
Authors: Aota Tatsuya , Takahashi Eiichi , Losev Leonid L. , Tabuchi Takeyuki , Kato Susumu , Matsumoto Yuji , Okuda Isao , Owadano Yoshiro
Published: July 2005

An ultraviolet (UV) short-pulse intensity diagnostic method using atmosphere as a nonlinear medium was developed. This diagnostic method is based on evaluating the ion charge of the two-photon ionization of atmospheric oxygen upon irradiation with a UV (238–299 nm) short-pulse laser. The observed ion signal increased proportionally to the input intensity to the power of ∼2.2, during the two-photon ionization of atmospheric oxygen. An autocorrelator was constructed and used to successfully measure a UV laser pulse of ∼400 fs duration. Since this diagnostic system is used in the open-air under windowless conditions, it can be set along the beam path and used as a UV intensity monitor.
Analysis of Physical Mark Length Variation for Write Strategy Optimization
Authors: Tao Jing
Published: July 2005

The physical mark length variation is analyzed to determine the relationship between write strategy parameters and measured mark runlength variation. A new approach is proposed to optimize the write strategy parameters on the basis of the mark runlength measurement. In this approach, multiple write strategy parameters are optimized simultaneously to reach the desired mark runlength target, thus the total data-to-clock jitter is minimized. The physical mark length variation caused by write strategy parameters is calculated on the basis of the mark runlength measurement. The experiments on high-speed phase-change recording verified the effectiveness of the optimization algorithm.
One-Dimensional Simulation of Electromagnetic Scattering from Moving or Vibrating Perfect Planes
Authors: Ho Mingtsu
Published: July 2005

The one-dimensional simulation results of the reflection of electromagnetic fields from moving or vibrating perfectly conducting planes are presented in this report. The computational results are obtained by the characteristic-based method with the application of the characteristic variable and relativistic boundary conditions. For the purpose of easy observation of relativistic effects on the reflected electromagnetic waves, the perfect conductor is set either to travel constantly or to vibrate sinusoidally such that the extreme instantaneous velocity is 10 or 20% of the speed of light. The theoretical Doppler shift values are used to examine the accuracy of numerical method. The computational results and the exact values are in good agreement.
Spreading of Droplets Impacting on Smooth Solid Surface
Authors: Gong Shih-Chin
Published: July 2005

An analytical model is developed to predict maximum droplet diameters after droplets impact on a smooth solid surface. The initial total energy of the droplet causes spreading on the substrate, which is opposed by viscous work, contact line work, and surface energy. In dimensionless form, the maximum spread factor can be expressed as a function of Reynolds number, Weber number, and advancing contact angle.
Theoretical Concept of Physical Antibiotics Using Nanoparticles
Authors: Naruse Yujiro
Published: July 2005

The concept of physical antibiotics using nanoparticles is proposed and a feasibility study is performed theoretically. The core operating principle is based on the temperature increase of nanoparticles adhering to an infected area (bacteria colony or biofilm) induced by applying an external magnetic field and electromagnetic waves. In the first phase, the magnetic field increases the temperature of the nanoparticles after their capture by the infection area. In the next phase, the nanoparticles form distributed dipole antennas that will absorb electromagnetic waves efficiently. The high-temperature nanoparticles will drill into the cell walls of the bacteria and consequently destroy the bacteria. There is a possibility that these physical antibiotics will solve the current problems related to conventional antibiotics.
Guiding Molecular Motors with Nano-Imprinted Structures
Authors: Bunk Richard , Carlberg Patrick , Månsson Alf , Nicholls Ian A. , Omling Pär , Sundberg Mark , Tågerud Sven , Montelius Lars
Published: July 2005

This work, for the first time, demonstrates that nano-imprinted samples, with 100 nm wide polymer lines, can act as guides for molecular motors consisting of motor proteins actin and myosin. The motor protein function was characterized using fluorescence microscopy and compared to actomyosin motility on non-structured nitrocellulose surfaces. Our results open for further use of the nano-imprint technique in the production of disposable chips for bio-nanotechnological applications and miniaturized biological test systems. We discuss how the nano-imprinted motor protein assay system may be optimized and also how it compares to previously tested assay systems involving low-resolution UV-lithography and low throughput but high-resolution electron beam lithography.
Al/AlN/InP Metal-Insulator-Semiconductor-Diode Characteristics with Amorphous AlN Films Deposited by Electron-Cyclotron-Resonance Sputtering
Authors: Saito Kunio , Ono Toshiro , Shimada Masaru , Shigekawa Naoteru , Enoki Takatomo
Published: July 2005

Amorphous AlN films deposited by sputtering using electron cyclotron resonance (ECR) plasma were used to form AlN/n-InP metal–insulator–semiconductor diodes. The AlN films were deposited without substrate heating. Capacitance–voltage (C–V) measurements showed a small hysteresis window of ∼35 mV for a 2-nm-thick AlN film, and frequency dispersion was much improved by post-deposition annealing at 200°C in an H2 gas atmosphere. We estimated the interface-trap density to be 3×1012 cm-2eV-1 by comparing 10-kHz and 1-MHz C–V curves. Small leakage currents of less than 2 mA/cm2 at a bias voltage of 1 V were obtained for the 2-nm-thick film. To clarify the effect of the deposition methods, AlN films were deposited by conventional magnetron sputtering. ECR sputtering provided better C–V and current-voltage characteristics than magnetron sputtering for as-deposited AlN films, showing that good metal–insulator–semiconductor (MIS) properties arise because of the suitable deposition method and the good combination of materials. An analysis of surface atoms on the InP substrate by secondary ion mass spectrometry showed a large oxygen concentration on the order of 1022 cm-3, which is not preferable for MIS diode properties. Surface cleaning using dilute HF reduced oxygen and carbon concentrations to less than half.
Nanomechanical Switch formed by Focused-Ion-Beam Chemical Vapor Deposition
Authors: Morita Takahiko , Kanda Kazuhiro , Haruyama Yuichi , Matsui Shinji
Published: July 2005

Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology for forming a free-space-nanowiring. At 295 K the electrical resistivity of a free-space-nanowiring made using phenanthrene as the source gas was 1×102 Ω cm. Adding tungsten hexacarbonyl to the phenanthrene reduced the electrical resistivity to 2×10-2 Ω cm. The nanomechanical switch composed of a coil and a nanowiring has been fabricated by using free-space-nanowiring fabrication technology, and its operation has been confirmed by applying a voltage.
Why Phase-Change Media Are Fast and Stable: A New Approach to an Old Problem
Authors: Kolobov Alexander V. , Fons Paul , Tominaga Junji , Frenkel Anatoly I. , Ankudinov Alexei L. , Yannopoulos Spyros N. , Andrikopoulos Konstantinos S. , Uruga Tomoya
Published: July 2005

Present-day multimedia strongly relies on re-writable phase-change optical memories. We find that, different from current consensus Ge2Sb2Te5 (GST), the material of choice in digital versatile discs–random access memory (DVD-RAM), possesses a structure similar to ferroelectric GeTe, namely that Ge and Sb atoms are located off-center giving rise to a net dipole moment. Amorphisation of both GeTe and GST results in a significant shortening of covalent bonds and a decrease in the mean-square relative displacement concomitant with a drastic change in the short-range order. We demonstrate that the order-disorder transition in GeTe and GST is primarily due to a flip of Ge atoms from an octahedral position into a tetrahedral position without rupture of strong covalent bonds. It is this nature of the transformation that ensures large changes in reflectivity, fast disk performance and repeatable switching over millions cycles.
Signal Enhancement of Super Resolution Enhanced Near-Field Structure Disc by Silver Nano-Particles
Authors: Kurihara Kazuma , Arai Tomofumi , Nakano Takashi , Tominaga Junji
Published: July 2005

We propose a carrier-to-noise ratio (CNR) increment method for a super resolution enhanced near-field structure (super-RENS) with silver nanoparticles. The silver nanoparticles were fabricated by the RF magnetron sputtering method. The mean diameters of the particles under as-deposited and 600°C annealed conditions were evaluated as 5 nm and 15 nm, respectively. The light absorption peak of the silver nanoparticles was adjusted to a laser wavelength of 405 nm for an optical disc system. The silver nanoparticles showed a higher absorption characteristic when they were annealed at above 500°C. In the case of a recording mark size of 50 nm, the CNR enhancement of the super-RENS with the silver nanoparticles was evaluated as 11 dB. This method using the silver nanoparticles provided a higher CNR increment in recording marks below the optical resolution limit.
Maximum Magnetic Field of Thin Film Coils in Magneto-Optical Heads
Authors: Vullers Ruud J. M. , Zieren Victor , Esch Harry van
Published: July 2005

We investigated the maximum current at which coils, integrated in magneto-optical recording heads, can be operated before breakdown, effectively determining the maximum magnetic field. At too high currents, the coil breaks down: either a rupture or a short between the turns occurs. However, already at some lower current, cracks appear in the optical aperture. Due to the cracks, the aperture is optically disturbed, which reduces the optical power during writing and readout. We show that the appearance of these cracks is temperature related. The current, at which the cracking occurs, can be determined by measuring the change of resistance of the coils. This determines the maximum magnetic field the coils can generate. We show that this maximum magnetic field can be increased by adding a NiFe layer underneath the coil, or by adding Cu pads, effectively cooling the coil.
Integrated Optical Unit for Magneto-Optical Pickups
Authors: Hirano Kenji , Miyake Tomoyuki , Ueyama Tetsuo , Ogawa Masaru , Numata Tomiyuki , Nakata Yasuo , Kurata Yukio
Published: July 2005

We have developed an integrated optical unit for magneto-optical (MO) pickups which contains three polarized holograms for detecting MO signals and servo error signals. In this study, we modify the integrated optical unit so that it can reproduce two types of discs using two photo detectors. The phase-shift differential push-pull method is used for the radial servo and it is compatible with different track pitches. We also discuss the quality of the reproduced MO signals.
Coupled-Field-Analysis and Dynamic Improvement of Ultraslim Optical Pickup Actuator
Authors: Lee Dong-Ju , Jung Gi-Won , Park No-Cheol , Yang Hyun Seok , Park Young-Pil , Song Byung Youn , Cho Won Ik , Seong Pyong Yong , Lee Kyoung Ho
Published: July 2005

We propose coupled-field analysis that enables the precise analysis of the dynamic characteristics of optical pickup actuators. The effectiveness of the proposed method is confirmed by applying it to improve the performance of an ultraslim pickup actuator by some optimization methods. The redesigned actuator is evaluated in dynamic experiments.
Correction of Substrate Vertical Birefringence Using Patterned Wave Plate
Authors: Katayama Ryuichi , Komatsu Yuichi
Published: July 2005

In an optical disk system in which an optical head with a polarizing optics is employed and light is focused through a substrate of the disk, the read/write characteristics of the system are degraded by the birefringence of the substrate. A polycarbonate substrate has both an in-plane birefringence and a vertical birefringence. The birefringence of the polycarbonate substrate is measured and its influence is estimated by a numerical calculation. It is understood that the in-plane birefringence simply decreases light intensity at the photodetector, while the vertical birefringence not only decreases light intensity at the photodetector but also increases a focused spot diameter on the disk and decreases the resolution of a radio frequency (RF) signal. A method of correcting the vertical birefringence using a newly developed patterned wave plate is proposed to improve the read/write characteristics of an optical disk system. Increases in the light intensity and resolution using a patterned wave plate are confirmed experimentally.
Fabrication and Characterization of Sub-100 µm Diameter Gallium Phosphide Solid Immersion Lens Arrays
Authors: Lang Matthew , Milster Tom D. , Minamitani Takahisa , Borek Gregg , Brown David
Published: July 2005

Fabrication and testing of a sub-100 µm gallium phosphide solid immersion lens is described with suitable sphericity (<160 nm deviation) to a marginal ray angle of 42° for NA up to 2.2 inside the material.
Feedback Light Coherence Issues in Micro Optical Pick-Ups
Authors: Wilson Bernard W. Bell Jr. and Scott D.
Published: July 2005

The conditions for optimizing laser feedback in small optical pick-ups using 660 nm strained quantum well laser diodes are discussed. Peaks in the coherence function occurring as a periodic function of the feedback path length are found to diminish rapidly once high frequency drive current modulation is applied. However, feedback path lengths less than 25 mm still show large values. This coherent feedback makes the laser sensitive to variations in the phase of the feedback light. The choice of the feedback path length is critical to eliminating these effects.
New Spherical Aberration Compensator for Blu-Ray Disc
Authors: Nakahara Hironori , Matsubara Daisuke , Matozaki Toshiya , Takeshita Nobuo , Yoshihara Toru
Published: July 2005

In high numerical aperture optical disc systems, a spherical aberration compensator is required to accomodate thickness deviations of the cover layer and the space layer. In some cases, a liquid crystal (LC) plate is employed as a spherical aberration compensator and it is generally attached to the objective lens actuator coaxial with the objective lens. It is useful to put the LC plate in a fixed part of the optical head to cope with high-speed disc rotation and to reduce the size of the objective lens actuator, but additional objective lens decentering against the LC plate is caused by the tracking operation. In this paper, a new spherical aberration compensator for Blu-ray Disc optical systems is introduced to decrease the wavefront aberration caused by objective lens decentering.
Head Analysis in Air Flow on Near-Field Optical Disk System with 2-Axis Actuator
Authors: Ishimoto Tsutomu , Ito Tatsumi , Shinoda Masataka , Saito Kimihiro , Kondo Takao , Matsui Takeshi , Kim Sunmin , Nakaoki Ariyoshi , Yamamoto Masanobu
Published: July 2005

Several near field optical disk systems have been proposed and are expected to be the tools for realizing large-capacity optical disk storage systems. However, there remains a concern as to whether removability can be realized in near-field optical disk systems. To resolve this concern, we analyze a near-field optical head installed onto a 2-axis actuator in an air flow. Finally, we conclude that a conical head and the active servo of a 2-axis actuator contribute to the stability of near-field playability with respect to dust robustness.
Effect of Particle Contamination of Objective Lens in a DVD-ROM Drive on Laser Diode Power and Photo Diode RF Signal
Authors: Lee Dae-Young , Pae Yang-Il , Lee Jaeho , Hwang Jungho
Published: July 2005

Air flow produced by disk rotation in an optical disk drive introduces air borne contaminant particles into the drive, which adhere to the objective lens and generates read/write errors. These particles are a serious problem for high-density storage devices and therefore, the effect of particle contamination in a digital versatile disk-read only memory (DVD-ROM) drive on laser diode power and photo diode RF signal was experimentally investigated. The laser power and amplitude of the photo diode RF were reduced, and the RF jitter was exponentially increased with increasing level of contamination of the lens. In addition, data could not be accessed when the contaminated surface area was greater than 20% of the lens surface area.
Fabrication of Slider-Type Near-Field Arrayed Probe for Optical Data Storage
Authors: Kim Eun-Kyoung , Lee Sung-Q , Park Kang-Ho
Published: July 2005

A near-field optical slider has been prepared for a high-density recording system. The slider includes an array of high-throughput near-field probes and the surface-air bearing of the slider has been designed for a flying height of 20 nm. We have developed a prior-etching process for hollowing out the silicon oxide near-field optical tips. Bottom silicon underneath the arrayed tips and the inner silicon of the tips have been successfully removed for the optical path of visible light.
Development of an Air Gap Servo System for High Data Transfer Rate Near Field Optical Recording
Authors: Lee Ju-Il , Aa Michael van der , Verschuren Coen , Zijp Ferry , Mark Martin van der
Published: July 2005

This paper describes development of a bi-axial actuator-based air gap servo system for a near field optical recording system using a blue laser and a solid immersion lens (SIL). We first present a new pull-in procedure ensuring smooth air gap servo start-up without lens-disc collision. Furthermore, a memory-loop control technique has been employed to realize a high-speed air gap servo system guaranteeing a high data transfer rate.
A Study of High-Gain Servo Controller with Complex Zeros for Optical Disk Drives
Authors: Urakawa Yoshiyuki , Watanabe Tetsu
Published: July 2005

As optical disk drives are increasingly used in various applications, their servo systems must be made more robust. Various control technologies have been studied, [rf1,rf2] but they require larger circuits and longer computational times. In this paper, a high-gain servo controller with complex zeros, which is the same order controller as the conventional controller, is proposed. The complex zeros allow higher gain without the loss of phase margin. We implemented the high-gain servo controller in a digital servo system. The discrete model of the digital servo system had 3 sampling time delays, and it caused an enhancement of disturbances at high frequencies. We suppressed the enhancement, using the pole assignment method directly in the discrete model. The experimental data had small rotational errors and good performance for torque disturbance.
Epitaxial Growth of (001)ZrN Thin Films on (001)Si by Low Temperature Process
Authors: Yanagisawa Hideto , Shinkai Satoko , Sasaki Katsutaka , Abe Yoshio , Sakai Akira , Zaima Shigeaki
Published: July 2005

We have prepared (001)ZrN films epitaxially grown on (001)Si substrates by a low temperature process using an ultrahigh vacuum magnetron sputtering system, and evaluated their epitaxial relationships and film qualities, using X-ray diffraction (XRD) analysis, X-ray pole figure, grazing incidence angle X-ray reflectivity (GIXR), transmission electron microscopy (TEM) and atomic force microscopy (AFM). It is clarified that (001)ZrN films grow epitaxially on (001)Si even at room temperature with the directional relationship of ZrN(001)[110]∥Si(001)[110], and the lattice mismatch at the interface between (001)ZrN and (001)Si is relaxed due to the existence of a very thin transition layer. It is also revealed from GIXR and AFM that the epitaxial ZrN films have a high film density and a flat surface morphology, irrespective of substrate temperature.
High-Performance Mixed PRML Architecture for Optical Data Storage System
Authors: Lee Junghyun , Ryu Eun-Jin , Lee Jae-Wook , Cho Eing-Seob , Konakov Maxim , Lee Jeongwon , Lee Jungeun , Chae Hyunsu , Lee Hanseoung
Published: July 2005

A new mixed analog/digital partial response maximum likelihood (PRML) architecture for the optical drive system is presented. To realize a high-speed, low-power and low-cost solution, new data and clock recovery circuits are proposed. The proposed architecture is based on the efficient combination of digital and analog circuits for providing high-speed and low-power data detection for optical data storage systems. The presented circuit shows increased operating speed by 67%, reduced power consumption by 28% and reduced area by 42%, therefore it provides a high-speed, low-power and low-cost system on chip solution for the future optical drive system. A test chip produced is fabricated using 0.18 µm CMOS technology and the product has been proved to demonstrate the performance of the proposed architecture.
Optimized Write Strategy for 4× Speed BD-RE
Authors: Hwang Wook Yeon , Lee Kyung Geun , Yang Chang Jin , Park In Sik
Published: July 2005

We studied an optimized write strategy for a 4× speed phase-change Blu-ray disc system for further practical implementation. This was performed by simulation using three-dimensional alternating directional implicit thermal analysis and crystallization modeling. We evaluated and confirmed this approach by implementing it in 2× recording with commercially available 23 GB discs.
Crosstalk Cancellation for 50-GB/Layer Optical Recording
Authors: Kudo Hiromi , Minemura Hiroyuki , Miyamoto Harukazu , Tamura Reiji , Adachi Kazuyoshi
Published: July 2005

We have developed write/read technologies for post-Blu-ray Disc (BD) with a capacity of 50 GB/layer. In this report, the authors propose a crosstalk cancellation method that minimizes the error between the crosstalk canceled signal and the target signal that is generated from the binary output of an adaptive-partial response maximum likelihood (PRML) decoder. The experimental results obtained using our method show that the bit error rate is reduced to 1/100. A high-density recoding of 50 GB/layer was demonstrated using our method.
Optimal Number of Control Bits in the Guided Scrambling Method for Holographic Data Storage
Authors: Kim Na Young , Lee Joohyun , Hong Youpyo , Lee Jaejin
Published: July 2005

One of the major concerns regarding data detection in holographic data storage systems is overcoming interpage interference (IPI). In general, the IPI can be reduced by making the number of 1 (light) and 0 (dark) pixels the same in a recorded page and to have as many transitions as possible produced in each row and column. Such requirements can be satisfied by the guided scrambling (GS) method. In this paper, we investigate the optimum number of control bits to form a page.
Signals from Multi-Level Run-Length-Limited Modulation Recordings Using Partial Response Maximum Likelihood
Authors: Jiang Sun-How , Kuo Ji-Wen , Ma Chang-Po , Lo Feng-Hsiang
Published: July 2005

Multi-level (ML) modulation recording technology increases the capacity of standard compact disc (CD) and digital versatile disc (DVD) rewritable systems without making changes to the optical/mechanical unit. In this paper, we introduce partial response maximum likelihood (PRML) technology to increase the accuracy of reading multi level signals from a ML-Run-length-limited (ML-RLL) recorded disc. Traditional slicer detection is no longer suitable for detecting multi-level run-length-limited signals. We also show several partial-response methods and their corresponding maximum-likelihood sequential estimation (MLSE) rules for ML-RLL modulation signal detection.
An 8-State DC-Controllable Run-Length-Limited Code for the Optical-Storage Channel
Authors: Noda Makoto , Yamagishi Hiroyuki
Published: July 2005

In order to apply iterative detection to the optical-storage channel, we have developed a dc-controllable 8-state rate-2/3 (1, 7) run-length-limited code with a maximum repeated minimum transition-run length of 5. The code can halve the size of hardware for a soft-input soft-output decoder, compared with that of the conventional 17PP code employed in the Blu-ray disc optical-storage system. The code also outperforms the 17PP code in bit-error rate when a low-density parity-check code is concatenated.
Read/Write Technology for 50 GB/layer at 100 Mbps
Authors: Hirotsune Akemi , Ushiyama Junko , Minemura Hiroyuki , Kudo Hiromi , Miyamoto Harukazu , Tamura Reiji , Adachi Kazuyoshi
Published: July 2005

We developed read/write technology for high-density optical data storage of 50 GB/layer at a data transfer rate of 108 Mbps. We demonstrated the writing and reading capabilities of a 50 GB/layer optical disk recording system at 36 Mbps with a sufficient power margin, using a three-beam crosstalk canceller with optical response equalizers, using a phase-change write-once disk. Bit error rates were below 1×10-4 at 108 Mbps. Experimental results showed that the technology realizes writing and reading densities two times higher and data transfer rates three times higher than those of Blu-ray with a simple optical component such as Blu-ray.
Application of Turbo Codes to High-Density Optical Disc Storage Using 17PP Code
Authors: Miyauchi Toshiyuki , Shinohara Yuji , Iida Yasuhiro , Watanabe Tetsu , Urakawa Yoshiyuki , Yamagishi Hiroyuki , Noda Makoto
Published: July 2005

We have previously proposed a novel trellis decoding technique for soft-output decoding of the 17PP code. Using this technique, we have developed a turbo-coded 17PP system, and showed improvement in the bit error rate (BER) in an additive white Gaussian noise (AWGN) channel by simulation. In this paper, we describe an optimized trellis of the 17PP code that has only 15 states and 53 branches. It is well known that a partial response (PR) channel can be regarded as a convo-lutional code with the trellis structure. Therefore we merged the PR1221 trellis into the 17PP trellis, which we call the “PR17PP” trellis, and similarly optimized this trellis. With the soft-in soft-out (SISO) decoders using this “PR17PP” trellis, it is experimentally confirmed that the turbo-coded 17PP system effectively increases the user capacity of an optical disc.
Hybrid Equalized Partial Response Path-Feedback Maximum Likelihood for 35.4 GB Blu-ray Disc ROM
Authors: Higashino Satoru , Kajiwara Yoshiyuki , Kobayashi Shoei
Published: July 2005

The decoding method with larger margin has been required according to the recent high density optical recordings. Since the optical reproduced signal has a strict cutoff of modulation transfer function (MTF), the high linear density equalization will cause the equalization error. In such a case, adaptive Viterbi [rf1,rf2,rf3] has been investigated as a decoding method which compensates tangential inter-symbol interference (ISI) and the scanty high frequency components. This fundamental theory is based on path feedback Viterbi detection. [rf4] We have developed hybrid equalized partial response path-feedback maximum likelihood (HEPR-PFML) which compensates the scanty frequency components more efficiently than conventional adaptive Viterbi. By using this system, the decoding performance is not only improved, but phase locked loop (PLL) will be stable because of the clear timing error information. We will show the experimental results for the higher density 35.4 GB Blu-ray Disc ROM (BD-ROM) than standard linear densities.
New Equalizer Optimization Method for Partial Response Maximum Likelihood Systems Using Normal Equation with Sequenced Amplitude Margin
Authors: Hayashi Tetsuya , Okumura Tetsuya , Akiyama Jun , Maeda Shigemi , Takahashi Akira
Published: July 2005

A new equalizer optimization method was proposed for partial response maximum likelihood systems. It provides a wider tangential tilt margin and defocus margin in an optical disk system that uses a blue laser (406 nm) and has a numerical aperture of 0.85.
Asymmetry Compensation by Nonlinear Adaptive Partial Response Equalizer for 31.3 GB Blu-ray Disk ROM
Authors: Kajiwara Yoshiyuki , Higashino Satoru , Yamagami Tamotsu
Published: July 2005

We investigated a nonlinear adaptive partial response equalizer for the asymmetry compensation of a 31.3 GB higher linear density Blu-ray disc read only memory (ROM) with a 16% asymmetry. A second-order adaptive Volterra filter approximately equalizes a nonlinear signal into a linear one. We reduced its calculation complexity to design a digital circuit in optimum hardware resources by the result of computer simulations. Then we designed an adaptive Volterra filter on an FPGA evaluation board for bit error rate measurements. Finally, we determined that an adaptive Volterra filter has a capability to obtain improved bit error rates by signal linearization in a conventional Viterbi detector for PR(1221).