bluuebunny/crossref_metadata_2025 huggingface dataset:
Coherent Control of the Polarization of Ultrashort Optical Pulses Using Electromagnetically Induced Transparency
Authors: Masahiro Takeoka Masahiro Takeoka , Daisuke Fujishima Daisuke Fujishima , Fumihiko Kannari Fumihiko Kannari
Published: October 2002

We propose a scheme of all-optical polarization switching in a four-level atomic system. In this scheme, the polarization state of an optical pulse is controlled by an another control pulse via a four-wave mixing (FWM) process between orthogonal components of a pulse. Using a sufficiently strong control pulse, a linear absorption loss during FWM is significantly suppressed, therefore the polarization can be controlled with high transmission efficiency. Since our scheme requires only one ground (stable) state, it is applicable to the excitonic systems of semiconductor quantum wells. Our numerical calculation, based on typical parameters of Pb-based inorganic-organic-layered perovskite-type materials, shows that, using ultrashort-pulse trains, polarization switching with a high repetition rate of more than 10 GHz is possible.
Behavior of Thermally Induced Defects in Heavily Boron-Doped Silicon Crystals
Authors: Jeong-Min Kim Jeong-Min Kim , Joon-Young Choi Joon-Young Choi , Hyon-Jong Cho Hyon-Jong Cho , Hong-Woo Lee Hong-Woo Lee , Hak-Do Yoo Hak-Do Yoo
Published: October 2002

The effect of the first-step heat treatment temperature on the bulk microdefect (BMD) and oxidation-induced stacking fault (OiSF) formation in two kinds of heavily boron-doped silicon wafers, with and without an OiSF ring area, were investigated by comparing it with that in lightly boron-doped wafers. The BMD density was observed to be higher in the heavily doped silicon than in the lightly doped one at the same oxygen concentration. Unlike in the lightly doron-doped silicon, in the heavily boron-doped silicon, OiSFs were formed over the entire wafer surface regardless of the OiSF ring position when the first-step heat treatment was carried out at 900°C.
Lattice Distortion in GaAsP Heteroepitaxially Grown on GaP and Si by Metalorganic Molecular Beam Epitaxy
Authors: Nakamura Kazuhiro , Hashimoto Tetsutaro , Yasui Toshiyuki , Yoshimoto Masahiro , Matsunami Hiroyuki
Published: October 2002

Lattice distortion in GaAsP layers has been studied using high-resolution X-ray diffractometry. GaAsP layers were grown on GaP and Si substrates by metalorganic molecular beam epitaxy (MOMBE), using triethylgallium (TEGa), tertiarybutylarsine (TBAs) and phosphine (PH3) as source gases. The lattice constants of epitaxial layers were obtained from the results of X-ray (004) and (115) diffraction. The lattice constant parallel to the growth surface (a
||
) was longer than the one perpendicular to the surface (a
⊥). The GaAsP epi-layer was two-dimensionally strained in the growth plane. This is explained by the difference of thermal expansion coefficients. The distortion in the GaAsP epi-layers on a GaP substrate was smaller than that on a Si substrate.
Electrical Properties and Thermodynamic Stability of Sr(Ti1-x,Rux)O3 Thin Films Deposited by Inductive-Coupling-Plasma-Induced RF Magnetron Sputtering
Authors: Ryoichi Ohara Ryoichi Ohara , Tatsuo Schimizu Tatsuo Schimizu , Kenya Sano Kenya Sano , Masahiko Yoshiki Masahiko Yoshiki , Takashi Kawakubo Takashi Kawakubo
Published: October 2002

Sr(Ti1-x
,Ru
x
)O3 (STRO) epitaxial thin films were deposited on single-crystal SrTiO3(100) substrates using the inductive-coupling-plasma-induced RF magnetron sputtering method without oxygen. The electrical conductivity of STRO films increases with Ru concentration and levels of the Ru 4d states are observed in the band gap of SrTiO3 by X-ray photoelectron spectroscopy (XPS) analysis. These results are consistent with those obtained by first-principles calculations. Thermodynamic stability increases with the decrease of Ru concentration, and STRO (x<0.50) is free from degradation under annealing H2 atmosphere at 600°C. This high resistance against reductive processes indicates that STRO (x<0.50) is one of the most suitable candidates for conductive oxide electrodes of oxide capacitors.
Characteristics of Pb(Zr0.52Ti0.48)O3 Thin Films on p-Si with a Buffer Layer of Bi4Ti3O12 Prepared by Pulsed Laser Deposition
Authors: Wang Hua , Yu Jun , Dong Xiaomin , Zhou Wenli , Wang Yunbo , Zheng Yuankai , Zhao Jianhong
Published: October 2002

The Pb(Zr0.52Ti0.48)O3 ferroelectric films with a c-axis oriented Bi4Ti3O12 buffer layer were deposited on p-Si(100) substrate by pulsed laser deposition (PLD) technique. The Pb(Zr0.52Ti0.48)O3 films were found to grow with a preferred orientation along (110) direction. Good ferroelectric properties were obtained for a 400 nm thick Pb(Zr0.52Ti0.48)O3/Bi4Ti3O12 film system with Au electrodes: P
r and E
c were 20 µC/cm2 and 48 kV/cm respectively. The memory window of capacitance–voltage (C–V) charactristics enlarged obviously and the current density reduced nearly two orders of magnitude after introducing the BIT buffer layer. The decay in remnant polarization was only 10% up to at least 109 bipolar switching cycles.
Thermochromic Properties of Double-Doped VO2 Thin Films Prepared by a Wet Coating Method Using Polyvanadate-Based Sols Containing W and Mo or W and Ti
Authors: Takahashi Ikuya , Hibino Mitsuhiro , Kudo Tetsuichi
Published: October 2002

A mixture of metallic vanadium, tungsten and molybdenum powder was dissolved in a hydrogen peroxide solution, to yield a polyvanadate sol containing W and Mo. A thin film of V1-x-y
W
x
Mo
y
O2 was fabricated on a fused silica substrate by spin-coating using such a sol followed by reduction in hydrogen and successive annealing in a nitrogen atmosphere. Thin films in the system V1-x-z
W
x
Ti
z
O2 were similarly prepared using a sol containing W and Ti. All the films obtained in this study showed a clear thermochromic switching performance with a large transmittance change in the infrared region. For V1-x-y
W
x
Mo
y
O2, the switching temperature (T
t) was lowered by doping at approximately T
t=T
t0 (=67°C)-ax-by, where a and b are the decrease rates of each individual dopant (about 1920 and 870°C, respectively, for 0≦x, y≦0.03). Doping of Ti had little effect on T
t, but markedly reduced hysteresis of the transition. We demonstrated that a double-doped film of V1-x-z
W
x
Ti
z
O2 (x=0.018 and y=0.10) showed thermochromic switching almost without any hysteresis at a temperature as low as 45°C.
Dry Etching Characteristics of Pb(Zr,Ti)O3 Films in CF4 and Cl2/CF4 Inductively Coupled Plasmas
Authors: Jung Jin-Ki , Lee Won-Jong
Published: October 2002

The dry etching mechanism of lead zirconate titanate (PZT) films was studied in high density CF4 and Cl2/CF4 inductively coupled plasmas. The concentrations of atomic Cl and F as well as the flux and energy of bombarding ions were monitored as a function of etching parameters such as etching gas ratio, substrate bias voltage (Vs), induction coil power and process pressure. The compositions and chemical bonding states of etched PZT films were examined by X-ray photoelectron spectroscopy (XPS). The etching of PZT films in CF4-based plasma is chemically assisted sputter etching, and the dominant step of the overall etching process is either the formation or the removal of the etch by-products, depending on the etching conditions. The etching of PZT films in Cl2/CF4 mixed plasma is mainly dominated by the formation of metal chlorides which depends on the concentration of the atomic Cl and the bombarding ion energy. The PZT film shows a maximum etch rate in 90% Cl2/(Cl2+CF4) plasma where the concentration of atomic Cl is maximum. The etch selectivity of PZT to Pt is less than 1.3 in CF4-based plasma, where as more than 2 in Cl2/CF4 mixed plasma. The amount of sidewall residue is greatly reduced in Cl2/CF4 mixed plasma compared with in CF4 plasma. A more vertical etch profile of PZT films can be obtained by lowering the process pressure and increasing the substrate bias voltage.
Analysis of Atomic Force Curve Data for Mapping of Surface Properties in Water
Authors: Sirghi Lucel , Nakagiri Nobuyuki , Sugimura Hiroyuki , Takai Osamu
Published: October 2002

This paper presents an analysis of atomic force versus distance curves for a silicon nitride probe and a silicon sample immersed in water. A custom-built atomic force microscope (AFM) was adapted for working in water by building a water cell from a liquid drop caught between a glass lamella fixed on the top of the cantilever base and the sample surface. An algorithm for processing of force curve data for long- and short-range forces is described. The force curve data taken for a sample consisting of a silicon wafer Si(111) patterned with V-shaped grooves and a silicon nitride cantilever in water were digitally acquired and automatically processed for mapping of surface properties. A weak repulsive double layer force with no relevant dependence on sample topography was observed on the force curves taken during approach movement of the cantilever. On the other hand, the attractive hydration force showed a strong dependence on the sample topography. Large hydration force values were noticed on the inclined faces of the V-shaped grooves while small hydration force values were noticed outside the grooves. The result was explained by the dependence of the tip curvature radius at the contact region on the tilt of the sample surface.
Reduction of Long-range Interactions using Carbon Nanotube Probes in Biological Systems
Authors: Maeda Yasushi , Nishijima Hidehiro , Akita Seiji , Matsumoto Takuya , Nakayama Yoshikazu , Kawai Tomoji
Published: October 2002

Carbon nanotubes (CNT) have been used as tips in non-contact atomic force microscopy (NC-AFM) to observe biomolecules including deoxyribonucleic acid (DNA) molecules. Adhesion and electrostatic forces, which affect NC-AFM measurements even in vacuum condition, can be drastically reduced by using a CNT tip without thermal treatments for samples. Consequently, stable imaging of DNA molecules was performed under the presence of a water layer and various surface charges on the substrate. This is highly advantageous for imaging biomolecules, which are denatured easily by thermal treatment.
Effects of Oxygen Concentration on Characteristics of RF-Sputtered In2O3–ZnO Thin Films
Authors: Park Seoung-Hwan , Kim Hwa-Min , Rhee Byung-Roh , Ko Eun-Young , Shon Sang-Ho
Published: October 2002

The effects of oxygen concentration on the electrical and optical properties of In2O3–ZnO films are investigated. In2O3–ZnO films deposited under the pure Ar gas show a resistivity of about 3.8 ×10-4 Ω·cm, comparable to that of indium-tin-oxide (ITO) films (∼10-4 Ω·cm), and an average transmittance of over 90% in the visible range. Thin films deposited at higher oxygen concentration also show larger absorption at about 400–500 nm compared to those deposited at the oxygen concentration of 0.0%. We propose that it is desirable to use pure Ar gas to obtain films with lower resistivity and higher transmittance in the visible range. Moreover, in the case of films deposited with a higher oxygen concentration, it is found that the resistivity significantly decreases with increasing heat treatment temperature.
Electrical Properties of (1-x)Ta2O5–xTiO2 Crystalline Thin Films Prepared by Metalorganic Decomposition
Authors: Salam K. M. A. , Konishi Hidekazu , Mizuno Masahiro , Fukuda Hisashi , Nomura Shigeru
Published: October 2002

Polycrystalline (1-x)Ta2O5–xTiO2 thin films were formed on a Si substrate by metalorganic decomposition (MOD) at an annealing temperature of 900°C. Thin films with 0.92Ta2O5–0.08TiO2 (x=0.08) composition exhibited superior insulating properties compared to other compositions. The main reason for the improvement in the insulating properties could be the charge compensation of excess oxygen by the TiO2 additive. The leakage current density was lower than 1×10-9A/cm2 up to an applied electric field of 3 MV/cm. The bulk-limited Poole-Frenkel conduction dominates the current–voltage characteristics. capacitance–voltage characteristics of these films showed good dielectric properties with a maximum dielectric constant of 16 and a charge-storage density of 42.5 fC/µm2 at 3 MV/cm.
Influence of Vacuum-Annealing Process on the Secondary Electron Emission Coefficient (γ) from a MgO Protective Layer
Authors: Jeoung Jin-Man , Lim Jae-Yong , Kim Young-Guon , Seo Yoonho , Cho Guang-Sup , Choi Eun-Ha
Published: October 2002

The secondary electron emission coefficient (γ) of vacuum-annealed MgO films has been investigated using a γ-focused ion beam (γ-FIB) system. The vacuum-annealed MgO films have been found to have higher γ values from 0.05 to 0.12 than those from 0.03 to 0.06 for as-deposited MgO films for operating Ne+ ions whose acceleration voltages ranged from 50 V to 200 V. It is shown that the γ for the as-deposited MgO protective layer is significantly decreased by the influence of holding in air since the hydroxyl OH groups are absorbed onto the MgO surface from the atmospheric air. It is also observed that the secondary electron emission coefficient γ for the vacuum-annealed MgO protective layer is less influenced by holding in air than that for the as-deposited MgO protective layer. Based on these findings, it is concluded that the vacuum-annealed MgO protective layer plays an important role in lowering the firing voltage in alternating current-plasma display panel (AC-PDP) compared with the as-deposited MgO protective layer or the as-deposited MgO protective layer held in air.
Prepulse Effect for Recombining Plasma Produced by Ultrashort High-Intensity Lasers
Authors: Woo Choi Il , A. Tanaka Hiroyuki Daido , Kunioki Mima Kunioki Mima
Published: October 2002

We compare the space-resolved characteristics of carbon plasmas produced using a single ultrashort high-intensity laser pulse (>1019 W/cm2) of less than 800 fs duration and those using a combination of a 100 ps duration prepulse and an ultrashort laser pulse. Profiles of electron density and electron temperature as functions of position from the original target surface are derived from the measured one-dimensional space-resolved soft X-ray spectra. The electron density was estimated from the Inglis-Teller limit and from a comparison of the experimental and the calculated profiles of Lyman series lines. The electron density gradually increases up to the critical density of the incident laser light near the target surface, and the density gradient is much steeper when the plasma is produced using the single ultrashort pulse. The electron temperature was estimated from the intensity ratio of the H-like Ly-β line to the He-like He-β line and that of the H-like Ly-α line to its satellite lines. The plasmas produced using the prepulse additionally are relatively uniform with moderate electron density and temperature, and a larger portion of the K-shell lines from carbon ions is produced in the recombining phase, rather than in the heating phase. With a suitable choice of prepulses, the spatial and temporal profiles of the plasma density and temperature can be controlled, which can facilitate applications of the laser-produced plasmas to various kinds of research, such as producing a gain medium for X-ray lasers.
Radial-Pumped Microchip High-Power Composite Yb:YAG Laser: Design and Power Characteristics
Authors: Pavel Nicolaie , Saikawa Jiro , Taira Takunori
Published: October 2002

We present a novel architecture for a quasi-four-level diode-pumped high-power microchip laser. The design uses a Yb:YAG core surrounded by an undoped YAG region of slab or disk shape, and that can be pumped from one side (unsymmetrical pumping) or from both slab sides (symmetrical pumping). Theoretical descriptions of the pumping optimization, pump-beam distribution, and output-to-input power characteristics are presented. The simulations show that from a composite Yb:YAG chip, which consists of a Yb:YAG core of 2.0-mm diameter and 13.0-at.% Yb concentration surrounded by an undoped YAG slab of 5.0-mm width and 0.8-mm thickness, a TEM00 output beam of 100 W continuous-wave power could be obtained. The expected optical-to-optical efficiency is 39%.
A Laser Thomson Scattering System for Low Density Glow Discharge Plasmas
Authors: ElSabbagh Mansour A. Mansour , Koyama Hiroki , Bowden Mark D. , Uchino Kiichiro , Muraoka Katsunori
Published: October 2002

A laser Thomson scattering system was constructed to measure the electron properties of capacitively-coupled radio-frequency glow discharges. The system was designed for the detection of the very small Thomson signal against a large background of Rayleigh scattered light. Measurement of electron density of 1015 m-3 order was achieved.
A Liquid Water Model That Explains the Variation of Surface Tension of Water with Temperaure
Authors: Khan Arshad , Khan M. Rezwan , Khan M. Ferdouse , Khanam Fahima
Published: October 2002

A model is presented that explains the variation of surface tension of liquid water with temperature. The presence of non H-bonding H (NHB H) atoms (defining surface of assumed clusters) together with H-bonding atoms, is considered in this treatment. A good agreement between the experimental and computed values suggests the validity of this model. The change in the number of NHB H atoms and density account for the variation of surface tension with temperature. Previously, the same model was applied to explain the anomalous variation of density of liquid water with temperature [A. Khan et.al.: Chem. Phys. Lett. 266 (1997) 473].
A New Multifunctional Sensor for Measuring Oil/Water Two-phase State in Pipelines
Authors: Sun Jinwei , Shida Katsunori
Published: October 2002

This paper presents a non-contact U form multi-functional sensor for the oil pipeline flow measurement. Totally four thin and narrow copper plates are twined on both sides of the sensor, from which two variables (capacitance, self inductance) are to be examined as the two functional outputs of the sensor. Thus, the liquid concentration (oil and water), temperature are finally evaluated. The flow velocity inside the pipeline could also be estimated by computing the cross correlation of the capacitance-pair. To restrain the effects of parasitic parameters and improve the dynamic response of the sensor, a proper shielding strategy is considered. A suitable algorithm for data reconstruction is also presented in the system design.
Hard X-Ray Microtomography Using X-Ray Imaging Optics
Authors: Akihisa Takeuchi Akihisa Takeuchi , Kentaro Uesugi Kentaro Uesugi , Yoshio Suzuki Yoshio Suzuki , Sadao Aoki Sadao Aoki
Published: October 2002

The first experiment to test the hard X-ray microtomography using X-ray imaging optics was carried out at the undulator beamline BL47XU of SPring-8. A Wolter type grazing incidence mirror was used as an objective. A charge coupled device (CCD) camera coupled with a phosphor screen and a relay lens (pixel size: 6 µm×6 µm, spatial resolution: 12.3 µm in full width at half maximum (FWHM)) was used as a detector. X-ray energy was selected to be 9 keV using a Si(111) double crystal monochromator. The magnification of the X-ray microscope system was 3.71 and the converted pixel size at the object plane was 1.6 µm×1.6 µm. Although three-dimensional images could not be obtained, Fresnel-fringe-free two-dimensional images were successfully reconstructed.
Diffraction-limited Microbeam with Fresnel Zone Plate Optics in Hard X-Ray Regions
Authors: Suzuki Yoshio , Takeuchi Akihisa , Takano Hidekazu , Ohigashi Takuji , Takenaka Hisataka
Published: October 2002

A hard X-ray microbeam with zone plate optics has been tested, and preliminary experiments on scanning microscopy have been performed. A Fresnel zone plate fabricated by the electron-beam lithography technique is used as an X-ray focusing device. The material of the zone structure is tantalum with thickness of about 1 µm, and the outermost zone width of the zone plate is 0.25 µm. A focused spot size measured by knife-edge scanning is 0.3 µm at an X-ray energy of 8 keV. Closer evaluation of the spatial resolution has been done by observing resolution test patterns in a scanning X-ray microscopy experiment, and fine patterns with a 0.2 µm-structure have been resolved.
Gradation Stitching Exposure Performance in the Improvement of Dose Uniformity and Continuity at the Field Stitching Boundaries
Authors: Horiuchi Toshiyuki , Mochida Hiroyuki
Published: October 2002

The effectiveness of gradation stitching exposure is demonstrated using a laboratory-built exposure system. After investigating convenient slit shapes, trapezoidal slits with an apex angle of 80° were adopted. From the viewpoints of ease of preventing corner rounding of exposure light flux and slit fabrication, trapezoidal slits were determined to be better than pentagonal slits. As the first experimental stage, exposure dose uniformity and continuity of the stitched parts are evaluated at the reticle plane in order to eliminate the complicated influence of the projection optics on patterns printed on wafers. Exposure and development of a special resist the dissolved depth of which after development changes almost linearly with the exposure dose is utilized for detecting partial irregular dose distribution in the narrow stitched parts. It is clarified that the dose inequality in the stitched parts is improved by adopting the gradation stitching exposure method. Moreover, by observing the line-and-space test pattern profiles and measuring the line pattern widths in the stitched parts, it is proved that the changes of top-view profiles and line widths are also very small and negligible. It will become difficult to develop a high-resolution projection optics with a large field for shorter wavelengths hereafter. Applying the gradation stitching exposure, large LSI chips will be replicated favorably by stitching two small scan fields. If a small field size is admissible, resolution and/or depth of focus will also be considerably improved.
Numerical Simulation on Read-Out Characteristics of the Planar Aperture-Mounted Head with a Minute Scatterer
Authors: Tanaka Kenji , Ohkubo Toshifumi , Oumi Manabu , Mitsuoka Yasuyuki , Nakajima Kunio , Hosaka Hiroshi , Itao Kiyoshi
Published: October 2002

Recently, various researches on optical recording based on near-field optical principles have been conducted for higher data storage density. However, there is a problem of the trade-off between signal output and spatial resolution, especially when an aperture-type near-field optical head is utilized for high speed data-readout. In order to solve this problem, we propose a novel near-field optical head, the planar aperture-mounted head with a minute scatterer, and analyze its read-out performance through the three-dimensional finite-difference time-domain (3D-FDTD) method. Our simulations reveal that the Silver scatterer placed at the center of the planar aperture strongly enhances optical energy due to the local surface plasmon excitation, and that this head has the potential to realize high resolution and high signal output simultaneously.
Jitter Analysis for Land/Groove Phase Change Disk
Authors: Ohkubo Akinori , Yanagisawa Takuma , Nomoto Takayuki , Ohsawa Seiichi , Yokogawa Fumihiko
Published: October 2002

A 22 GB optical video recording system with an objective lens of high numerical aperture (NA), a blue laser and a thin cover layer is proposed. We classify the jitter which increased by aberrations into three components for this system. We analyze the dependence of jitter components on the groove depth in detail. Furthermore, we confirm advantages of the limit equalizer (Limit-EQ) and the two-dimensional adaptive equalizer for the land/groove (L/G) phase change disk.
Spectro-Ellipsometry Investigation of Cascaded Crystallization Behavior of Phase-Change Ge–Sb–Te Alloy
Authors: Kim Sang Youl , Kim Sang Jun , Lim Hanjo , Lah Sang Moo , Park Young Dong , Jeong Tae Hee , Seo Hun
Published: October 2002

The cascaded crystallization behavior of phase-change Ge–Sb–Te alloy films has been confirmed by spectroscopic ellipsometry. The evolution of crystallinity analyzed by spectro-ellipsometry showed strong correlation with that revealed by the X-ray diffraction patterns. The depolarization effect in each stage of the cascaded crystallization process is discussed.
Properties and Reactive Sputtering Parameters of GeN Film for High-Density Phase-Change Optical Disk
Authors: Miao X. S. , Chong T. C. , Shi L. P. , Tan P. K. , Li J. M. , Lim K. G.
Published: October 2002

The dependence of optical and thermal properties of phase-change optical disks on the diffusion of sulfur atoms from ZnS–SiO2 dielectric layers into a GeSbTe phase-change recording layer was simulated. The influence of reactive sputtering parameters on the properties of GeN films has also been studied. Significant improvement in the direct overwriting cycles was achieved in the 4.7 GB digital versatile disk-random access memory (DVD-RAM) disk with a GeN interface layer after optimizing the sputtering parameters of the GeN film.
Influence of Groove Shape on Rear Expansion Detection Readout
Authors: Takahashi Koyata , Tsunashima Shigeru
Published: October 2002

We have investigated the influence of groove shape and recording scheme on readout of rear expansion detection (RED) magneto optical media. Marks recorded by laser pulse magnetic field modulation (LP-MFM) were found to expand without a field while those recorded by light intensity modulation (LIM) required a field for expansion. Media with steep wall grooves showed a high carrier-to-noise ratio (CNR) of 42.7 dB at a mark length of 0.2 µm when recorded by LP-MFM and required a low readout field of less than 100 Oe even when recorded by LIM.
Optical Storage System for 0.4 mm Substrate Media Using 405 nm Laser Diode and Numerical Aperture 0.60/0.65 Objective Lens
Authors: Ko Jungwan , Park In Sik , Yoon Du-Seop , Chung Chong-Sam , Kim Yoon-Gi , Ro Myong-Do , Doh Tae-Yong , Shin Dong-Ho
Published: October 2002

The most important application of the blue-laser optical storage system is the recording high-definition digital broadcasting. For this application, the next-generation blue laser optical storage system requires a data capacity of at least 2 h of a digital broadcasting data stream with a data transfer rate of 23.5 megabits per second (Mbps). In addition to the capacity goal, system compatibility with the conventional digital versatile disc (DVD) system as well as the compact disc (CD) system is important. In order to satisfy the requirements of blue-laser optical storage, a system for media with a substrates thickness of 0.4 mm was proposed, and improved molding technology, crosstalk cancellation technology, dynamic tilt compensation technology and quadrature phase shift keying (QPSK) modulated wobble addressing method were developed for the system. We confirm the feasibility of the proposed system for media with a 0.4 mm substrate using a 405 nm blue laser diode and objective lens with a numerical aperture (NA) of 0.6 (0.65 for rewritable system).
Study of Oxygen-Doped GeSbTe Film and Its Effect as an Interface Layer on the Recording Properties in the Blue Wavelength
Authors: Hee Jeong Tae , Lyul Lee Hun Seo , Min Choi Sung , Jun Kim Sang , Youl Kim Sang
Published: October 2002

An oxygen-doped GeSbTe interface layer improves the overwriting characteristics of the phase-change optical disk in the blue wavelength. The thermal and optical properties of oxygen-doped GeSbTe film and its crystal structure were investigated. Crystallization temperature and activation energy of the amorphous Ge–Sb–Te–O films are increased with the oxygen concentration while the melting point is decreased. The refractive index of the crystalline state monotonically increases with the oxygen concentration of the film, while its extinction coefficient monotonically decreases. In terms of the crystalline structure, fcc characteristic peaks disappear gradually with oxygen concentration, and above 35 at.% of oxygen, hexagonal peaks appear.
Photoaddressable Polymers for Rewritable Optical Disc Systems
Authors: Sabi Yuichi , Yamamoto Masanobu , Watanabe Hidetoshi , Bieringer Thomas , Haarer Dietrich , Hagen Rainer , Kostromine Serguei G. , Berneth Horst
Published: October 2002

We present results of the feasibility study on photoaddressable polymers (PAPs) applied to optical disc systems. PAPs represent a new class of organic rewritable materials that exhibit a huge signal birefringence (Δ
n) at the readout wavelength. By optimizing the disc structure and the readout optics, the signal amplitude is proved to be sufficient for the optical disc systems. A low noise profile and sharp recording profile led to a maximum carrier-to-noise ratio (C/N) of 58 dB and a clear eye-pattern. They also showed a potential for multi-level recording, since the recording was dominated by a pure photon mode.
High-Density Read-Only Memory Disc with Super Resolution Reflective Layer
Authors: Kikukawa Takashi , Kato Tatsuya , Shingai Hiroshi , Utsunomiya Hajime
Published: October 2002

We report that super-resolutional readout occurred in read-only memory (ROM) discs with very simple materials and structure. By adopting a 15-nm-thick layer of Ge, Si, Mo, and W as a reflective layer, a carrier-to-noise ratio over 40 dB could be obtained from small pits which were below the resolution limit of our optical system. Experimental and thermal simulation results showed that the super resolutional readout phenomenon in the discs is strongly correlated to the film temperatures that are reached when a laser spot is irradiated on the films. Signal characterizations suggest that the super resolutional readout mechanism of the discs is different from those of conventional ROM and conventional super-resolutional ROM discs. We have named them “Super-ROM” discs.
Magneto-Optical Characteristics Enhanced by Super Resolution Near Field Structure
Authors: Kim Jooho , Fuji Hiroshi , Yamakawa Yuzo , Nakano Takashi , Buechel Dorothea , Tominaga Junji , Atoda Nobufumi
Published: October 2002

Using a silver oxide thin film of a non-magnetic mask layer, the magneto-optical (MO) recording signals were enhanced by surface plasmon. A resolution of less than 170 nm was achieved by the near-field coupling between a light-scattering center generated in the AgO
x
film and the light polarization of MO marks. The electrical field intensity was also confirmed by a computer-simulation. Optimization of the disk structure and materials, and the effects of readout power were investigated.
A Format of High-Density Rewritable Optical Disk using Groove Recording
Authors: Tonami Junichiro , Chaen Shuichiro , Mochizuki Masaki , Kondo Tetsuya , Nakamura Hideki , Nakagawa Eiji , Ohshima Katsunori , Oki Tsuyoshi , Hayami Atsushi , Itonaga Makoto
Published: October 2002

A new physical format using groove recording and new signal processing techniques is discussed. The signal reproduction of shallow pre-embossed pits was confirmed with a technique utilizing tangential push-pull (TPP) and a compatible partial response (PR) equalizing system. An evaluation in terms of the bit error rate by hardware experiments is demonstrated.
Phase Change Disc for High Data Rate Recording
Authors: Inoue Hiroyasu , Hirata Hideki , Kato Tatsuya , Shingai Hiroshi , Utsunomiya Hajime
Published: October 2002

We have developed a phase change disc having a thin transparent cover layer corresponding to the new optical recording system (DVR) using a blue laser (405 nm) and a numerical aperture (NA) of 0.85. We have achieved a user capacity of 22 GB per side of the 120 mm diameter disc, and a user data recording rate of 70 Mbps by designing a highly flat transparent cover layer, a recording layer having high crystallization speed and a film structure for rapid cooling.
A New Structure of Super-Resolution Near-Field Phase-Change Optical Disk with a Sb2Te3 Mask Layer
Authors: Shi Lu Ping , Chong Tow Chong , Miao Xiang Shui , Tan Pik Kee , Li Jian Ming
Published: October 2002

A super-resolution near-field phase-change optical disk with a new mask layer of Sb2Te3 was studied. The disks were fabricated and characterized. The problem of thermal stability for the conventional Super-RENS (Super-Resolution Near-field Structure) was studied for the first time. In order to solve the problem of poor thermal stability, two new structures with a thermal shield layer that can significantly improve thermal stability were proposed, fabricated, and analyzed. Recording marks as small as 56 nm were observed.
Experimental Results of 3-piece 0.4 mm Molded Substrate
Authors: Ro Myong-Do , Lee Kyung-Geun , Yoon Du-Seop , Hwang In-Oh , Park Chang-Min , Kim Yoon-Gi , Park In-Sik , Shin Dong-Ho
Published: October 2002

To achieve the same margin as that of the digital versatile disk (DVD), using a 0.4 mm substrate has been molded for a high-density optical disk for double-sided dual layer disk. In this paper, the characteristics of a read-only and rewritable high-density optical disk of 0.4 mm plastic substrate is reported using a new resin material for injection molding, to improve both the birefringence and the mechanical characteristics.
Optical Disk Mastering Using Optical Superresolution Technique
Authors: Shieh Han-Ping D. , Tsai Shih-Yaon , Peng Yi-Hsing , Hsieh Tsung-Eong
Published: October 2002

A new laser lithography technique using the effect of optical superresolution can effectively reduce the exposed spot size on a photoresist layer, thus allowing disk mastering toward higher density using an existing light source and optics. A thin metallic mask layer deposited on the top of the photoresist layer is used to obtain a “below optical diffraction limit” linewidth on the photoresist layer. The feasibility of the laser lithography technique, as evaluated by simulation and experimental results, revealed that the linewidth on the photoresist layer could be shrunk by more than 50% of the diffraction limit of the optical system.
An Advanced Signal Detection Technique for Digital Versatile Disc Systems
Authors: Seob Cho Eing , Soo Cho Yong
Published: October 2002

We compare various signal detection techniques for high-density digital versatile disc (DVD) systems in terms of performance and hardware complexity, and propose a fixed-delay trellis search with decision feedback (FDTrS/DF) suitable for ASIC chip implementation. Based on various simulation and implementation results, it is shown that the proposed FDTrS/DF provides the best performance among various signal detection techniques, such as partial response maximum likelihood (PRML), decision feedback equalizer (DFE), fixed-delay tree search with decision feedback (FDTS/DF), and signal space detection with decision feedback (SSD/DF), even with low hardware complexity.
Byte Merging Inter-Row Interleaving Scheme for the Error Control of High-Density Digital Versatile Disk
Authors: Daeyon Kwak Daeyon Kwak , Jaehyung Kim Jaehyung Kim , Jaejin Lee Jaejin Lee , Jun Lee Jun Lee , Heungsang Jung Heungsang Jung
Published: October 2002

An efficient interleaving scheme, named byte merged inter-row interleaving (BMIRI) for an error correction code (ECC) block in the higher density digital versatile disk-random access memory (DVD-RAM) is presented. The error correction performance with the BMIRI has been investigated by computer simulations for various long burst and short burst errors. The results show that the BMIRI is effective for ECC block of higher density DVD-RAM.
Digital Holographic Memory Using Two-Dimensional Modulation Code
Authors: Kume Tatsuya , Yagi Shogo , Imai Tadayuki , Yamamoto Manabu
Published: October 2002

The degradation of reconstructed images from a digital holographic memory that uses highly sensitive strontium barium niobate as a recording medium was reduced using two-dimensional modulation codes that have low average intensity and high coding efficiency. The signal-to-noise ratios of the reconstructed images and hence the bit error rates of the data retrieved from the images were improved without reducing the coding efficiency.
Designing Center Error Control in Optical Disc Drive Systems
Authors: Kyung-Soo Kim Kyung-Soo Kim , Seong-Pyo Hong Seong-Pyo Hong
Published: October 2002

In this paper, the feedback control system for controlling the center error which represents the vibration of the object lens of the pick-up during the movement of the coarse actuator is considered. The center error signal measured from the push-pull signal is corrupted by the track-cross noise, which degrades the control performance. Through the experiments, we discuss a few issues related to the center error control for improving the quality of the compact disc player as an audio-video equipment.
Inner Area Aberration Compensating Lens for Compact Disc (Compact Disc-Recordable)-Digital Versatile Disc Compatible Head
Authors: Hayashi Hideki , Yamamoto Hiroaki , Anzai Joji , Kamei Tomotada , Mizuno Sadao , Tanaka Yasuhiro , Yamagata Michihiro
Published: October 2002

We have developed a dual-wavelength digital versatile disc(DVD)/compact disc(CD)-compatible inner area aberration compensating lens capable of reading compact disc-recordable (CD-R) disks. In order to be able to read CD and CD-R disks with an infrared laser, it is essential to increase the numerical aperture (NA) of the inner area, but the resulting deterioration of the read signal has been a problem. Performance levels that enable DVD disks to be read have been achieved by reducing the fifth-order spherical aberration (SA5) by means of a phase step.
A Novel Pickup Head Design for DVD-Multi System
Authors: Huang Der-Ray , Ju Jau-Jiu , Wei Li-Ding , Chang Chi-Lone , Shih Hsi-Fu , Yang Tzu-Ping
Published: October 2002

This paper introduces a novel holographic optical element (HOE) pattern design to generate focusing and tracking signal for using in digital versatile disc DVD-multi pickup heads. The digital verstile disk (DVD) multi drive will be able to read disks written in the DVD-ROM, DVD-video, DVD-audio, DVD-R/W, and DVD-R formats. DVD multi drive will also be able to write disks in the DVD-RAM and DVD-RW/R formats. The HOE design provides the focusing error signal and both differential phase detection (DPD) and pushpull tracking signals for DVD-ROM disks and rewritable land-groove disks. The HOE pattern is divided into two main regions. The inner region is for focus detection and the outer region is for DPD and Pushpull tracking detection. In this study, a rotary actuator is used to reduce the tilt angle of the objective lens in the DVD-multi pickup head. The finite element method of the actuator is studied to analyze the resonance of the structure and the magnetic field of the voice coil motor.
An Integrated Magneto-Optical Sliding Head for First Surface Laser Pulsed Magnetic Field Modulation Magneto-Optical-Recording
Authors: Penning Frank C. , Kesteren Hans W. van , Aa Michael A. H. van der , Martynov Yourii V. , Vullers Ruud J. M.
Published: October 2002

A sliding head with integrated focusing lens and magnetic field modulation coil has been designed and manufactured. The component can be used for high data rate, first surface magneto optical recording with a NA=0.85 and λ=400 nm. A coil is integrated into the air bearing surface of a slider to maintain a head-disk distance of around 1 µm. It can generate at least a 200 MHz modulated magnetic field of 15 kA/m fieldstrength. We have tested the coil, slider performance and two stage tracking by using a flat 0.6 mm thick slider.
Parallel Recording Array Head of Nano-Aperture Flat-Tip Probes for High-Density Near-Field Optical Data Storage
Authors: Kim Young-Joo , Suzuki Kazuhiro , Goto Kenya
Published: October 2002

Increasing the memory capacity and data transfer rate of optical data storage to match the market requirements is now a challenging task. To realize a more effective and simple memory system, a parallel near-field optical system has been proposed using vertical cavity surface emitting laser (VCSEL) microprobe array heads. The concept, structure and fabrication process of new flat-tip microprobe arrays have been discussed and realized by the preparation of a silicon probe array in this research. Flat-tip probes are advantageous for improving optical properties since they are prepared from materials of high refractive index and the array shows good structural design for the contact head system with good uniformity of the probe height. We have successfully prepared Si nano-aperture probe arrays with the aperture size of 150 to 500 nm using microfabrication techniques, including photolithography, wet chemical etching, and a newly developed aperture formation process which uses a SiO2 mask layer. The microstructural observation of Si flat-tip probe arrays is in good agreement with our design concepts and supports the strong possibility of their application to actual recording heads. We are now developing a monolithic nano-aperture VCSEL probe to complete our parallel near-field optical system with high memory capacity and fast transfer rates in the near future.
Volume Holographic Device for Spherical Aberration Correction and Parallel Data Access in Three-Dimensional Memory
Authors: Suk-Chun Lee Suk-Chun Lee , Wataru Inami Wataru Inami , Yoshimasa Kawata Yoshimasa Kawata
Published: October 2002

We propose a volume holographic device for spherical aberration correction and parallel data readout in three-dimensional optical memory. Since the volume holographic device has high angular selectivity and wavefront conversion property, it is possible for that the volume holographic device can achieve data separation in each layer and the correct the spherical aberration which is generated when the data in deep layers are read or written. We present the theoretical analysis of parallel readout property using Kogelnik's diffraction theory [Kogelnik: Bell Syst. Tech. J. 48 (1969) 2909]. We also demonstrate some experimental results of the volume holographic device.
Analysis of Atomic Force Microscopy Images of Crystal Originated “Particles” on Silicon Wafers Treated with NH4OH:H2O2:H2O Solution
Authors: Lee W. P. , Seow W. S. , Yow H. K. , Tou T. Y.
Published: October 2002

Crystal-originated particle (COP) side-wall angles and rates of change in width were measured after treatment in an SC-1 solution by atomic force microscopy (AFM) to determine the shape, size and type of the particles on a polished (100) Si wafer surface. The etched silicon tip's maximum measurable slope angles were used to determine whether a COP originated from either the upper or the lower portion of an octahedral void. If the COP side-wall angle is equal to the maximum measurable slope angle of around 72°, the COP originated from the upper portion of the void. The lower portion of an octahedral void corresponds to a side-wall angle of 55°. This was confirmed through the study of COP width changes in NH4OH:H2O2:H2O (SC-1) solution. The COP width depends on the rates of change in width and the shape of its void. The rates of change of width of the COP which originated from the lower portion of the void was found to be 0.8 nm/min whereas that of the COP which originated from the upper portion of the void was 2.5 nm/min. It is also shown that a perceived single-type COP could very well be the upper part of a twin-type COP, which reveals its form of a much larger geometry only after the wafers are dipped repeatedly in the SC-1 solution.
iD PHOTO System –Digital Photo Media for Still Cameras–
Authors: Watanabe Hiroshi , Ichiura Syuichi , Kawakami Kouichi
Published: October 2002

We developed a 50-mm-diameter magnetooptical disk system, iD PHOTO as a next-generation system for digital still cameras. The iD PHOTO system is based on the advanced storage magneto optical disk (AS-MO) standard, [rf1,rf2,rf3,rf4] and its media has a maximum capacity of 730 MB on a 50-mm-diameter single-sided disk, which exceeds the compact disc (CD) capacity, while being the world's smallest [rf5] rewritable optical disk. Using this system, it is possible to rewrite data at a high speed of more than 20 Mbps over one million times and moreover, it is suitable for saving data over long periods. Employing the magnetic field modulation (MFM) recording method and the center-aperture-detection (CAD)-type magnetic superresolution (MSR) readout method, the iD PHOTO system realizes high-density recording. The non return to zero inverted plus (NRZI+) modulation and the external clocking system enable high-capacity user data. Finally, we show that the read and write characteristics, which are sufficient for realizing a stable system, are obtained using external clocking and the CAD-type MSR readout method.
Format Description and Evaluation of the 22.5 GB Digital-Video-Recording Disc
Authors: Kees Schep Kees Schep , Bert Stek Bert Stek , Roel van Woudenberg Roel van Woudenberg , Martijn Blüm Martijn Blüm , Shoei Kobayashi Shoei Kobayashi , Tatsuya Narahara Tatsuya Narahara , Tamotsu Yamagami Tamotsu Yamagami , Hiroshi Ogawa Hiroshi Ogawa
Published: October 2002

We describe the format of the 22.5 GB rewritable digital-video-recording (DVR) system. The format is based on an objective lens with a high numerical aperture (NA=0.85), a thin cover layer (0.100 mm thick), and a blue-laser diode (λ=405 nm). We discuss experimental verification of the format and possible future extensions. The DVR system is well suited to be the basis of a third-generation optical-recording family for high-definition video recording.
Near-Field Optical Recording on a Pre-Grooved Phase-Change Disk in the Blue-Violet
Authors: Ichimura Isao , Kishima Koichiro , Saito Kimihiro , Yamamoto Kenji , Kuroda Yuji , Iida Atsushi , Masuhara Shin , Osato Kiyoshi
Published: October 2002

Near-field optical recording was implemented on a pre-grooved phase-change disk by using a φ1 mm superhemispherical solid immersion lens (SIL) of 1.5 numerical aperture. The SIL unit was mounted on a two-axis actuator for enabling both gap-height and tracking controls. The gap height was precisely adjusted with a capacitance formed between the SIL and disk materials. Groove structures were fabricated on a glass substrate by a reactive-ion-etching (RIE) process and flattened with spin-on-glass (SOG) coating for obtaining reliable push-pull tracking error signals. The phase-change layer stack was optimized by a vector diffraction analysis in order to maximize evanescent coupling at the gap height as small as 50 nm. A bit density of 80 nm was demonstrated on the land of a pre-grooved disk at the wavelength of 407 nm.
Near-Field Signal Detection Using Sub-Wavelength Sized Planar Aperture Slider on Oxide Ferrite Media
Authors: Yoshikawa Hiroshi , Andoh Yasuko , Baubet Carole , Furuya Akinori , Tanabe Takaya , Yamamoto Manabu
Published: October 2002

Optical transmission and surface characteristics of oxide ferrite (Fe3O4) as a write-once medium for near-field optical surface recording were investigated. Narrow line patterns were recorded on the surface of as-sputtered Fe3O4 (100 nm thick) using cw laser (532 nm) under various laser powers. Optical transmission intensities under far-field and near-field illumination methods were compared. Near-field signals exhibited signal transition width close to the aperture width, indicating high near-field readout resolution. However normalized transmission intensities were nearly the same, suggesting that signal characteristics depends on the recorded pattern not on the illumination method. No surface deformation were observed using atomic force microscope for low write power range (2.6–3.4 mW). Therefore, laser illumination of the medium surface probably causes a local oxidization of Fe3O4 to defect spinel ferrite (γFe2O3) resulting in a purely optical change without any surface deformation. Surface hardness and roughness were comparable with conventional hard disk surfaces.