bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of the Radiation Field Waveforms Produced by Lightning Return Strokes
Authors: Lee Bok-Hee , Eom Ju-Hong , Kang Sung-Man , Paek Seung-Kwon , Kawamura Tatsuo
Published: February 2005

Some features of the radiation field waveforms produced by cloud-to-ground lightning return strokes were investigated. A transient analyzer was used together with electric and magnetic field measuring devices with frequency bandwidths of 200 Hz to 1.6 MHz and 270 Hz to 2.3 MHz, respectively. The initial peak of the first lightning return stroke fields is followed by several large subsidiary peaks, whose amplitudes are a fraction of that of the initial peak and decrease with time. The subsidiary peaks of the first lightning return stroke fields may be caused by the effect of branches of leader channels. The mean amplitude ratios of the subsidiary peaks to the first return stroke field peak were widely distributed over the ranges of 0.25–0.8, and the mean time interval between the subsidiary peaks ranged from 5 to 15 µs. Detailed statistical analysis showed that the time interval between the subsidiary peaks and the ratio of the subsidiary peaks to the first lightning return stroke field peak in the present work are less than those obtained in subtropical and tropical regions. The parameters characterizing the wave tail of lightning return stroke fields are closely related to the propagation velocity and length of return stroke throughout the entire leader channel, and the subsidiary large pulses in the wave tail of return stroke fields seem to be associated with the resonance in major branches of lightning return stroke channels.
Hund's First and Second Rules in Spherical Quantum Dots (I) in the Zero-Magnetic Field
Authors: Asari Yusuke , Takeda Kyozaburo , Tamura Hiroyuki
Published: February 2005

We theoretically studied the validity of Hund's first and second rules in the three-dimensionally spherically parabolic quantum dot (3D-SPQD). We extended the unrestricted Hartree–Fock (exUHF) approach in order to determine the ground state while conserving the expectation values of the total orbital angular momentum <\hatL
2> and its z component <\hatL

z
> during the scf procedure. We applied this exUHF method to a GaAs 3D-SPQD and obtained the ground-state energy spectra. Our calculation reveals that, among those states having the largest spin multiplicities, the state giving the largest value of <\hatL
2> is energetically more stable than the others having a smaller value of <\hatL
2>; that is the spin filling in the 3D-SPQD obeys Hund's first and second rules.
Multiscale Simulation of Two-Dimensional Self-Organization of Nanoparticles in Liquid Film
Authors: Fujita Masahiro , Nishikawa Hiroyuki , Okubo Tatsuya , Yamaguchi Yukio
Published: February 2005

A set of numerical models for two-dimensional self-organization of nanoparticles in a liquid film is developed and numerical simulations are carried out to investigate the relationship between process conditions and structures of self-organized nanoparticles. The two-dimensional Langevin equation is employed to track nanoparticles on a substrate over time. Each nanoparticle is subject to multiscale surface forces such as capillary force, contact force, electrostatic force, van der Waals force and friction force, as well as Brownian force and fluid drag force. The modeling shows that no surface force can be neglected in the self-organization process because the magnitude of the surface forces strongly depends on the interparticle distances and the thickness of the liquid film. Three principles of two-dimensional self-organization are proposed on the basis of the unsteady behavior of the nanoparticles. The isotropic ordering factor and the non-dimensional boundary length are introduced to quantify the structures of self-organized nanoparticles. Every structure of the nanoparticles obtained here can be classified according to sets of these criteria.
Study of Si Nanostructure in SiO2 layer by Si+ Implantation and Rapid Thermal Annealing
Authors: Lu Fu-Fa , Lin Tung-Hsien , Kao Chin-Hsing
Published: February 2005

In this paper, a process of controlling the size of silicon (Si) quantum dots in SiO2 layers by Si+ implantation and rapid thermal annealing (RTA) is proposed. Through the proposed process, nanoscale Si islands in the range of 2–5 nm have been generated and then analyzed by various techniques including photoluminescence (PL) analysis, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The characterization results are consistent with the results of theoretical computation based on the quantum confinement model by the finite-element method (FEM). The proposed process and results will be helpful in developing single-electron devices.
Preparation and Electronic Properties of Nanoporous Carbon Inverse Opal
Authors: Take Hiroyoshi , Matsumoto Tetsuya , Hiwatashi Shinji , Nakayama Tadachika , Niihara Koichi , Yoshino Katsumi
Published: February 2005

Carbon inverse opals with three-dimensional nanoporous structures are fabricated by a template method using synthetic opals formed by the sedimentation of SiO2 spheres. The pore size of the carbon inverse opals ranges widely from approximately 11 nm to 1 µm depending on the diameter of the SiO2 spheres. The nanostructure size and the degree of graphitization of carbon are also controlled by the change in pyrolysis technique. X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations of the carbon inverse opals prepared by pyrolysis at a heat-treatment temperature (HTT) of 2800°C revealed that the graphite layers are formed in the area surrounding the pore and the degree of graphitization depends on the pore size. The electronic properties of the carbon inverse opals are dependent on pore size and the conditions of pyrolysis and are interpreted to be influenced by weak localization effect by taking into consideration the degree of graphitization depending on pore size.
Crystallization and Raman Shift of Array-Orderly Silicon Nanowires after Annealing at High Temperature
Authors: Niu Junjie , Sha Jian , Yang Qing , Yang Deren
Published: February 2005

Ordered silicon nanowires (SiNWs) with single crystal structure were synthesized using nanochannel-Al2O3 (NCA) and the chemical vapor deposition (CVD) method. Firstly, the SiNWs with nearly amorphous structure were fabricated at 500°C; then the SiNWs with crystalline structure were obtained by annealing an as-received sample at 800°C. The average diameter and length of the SiNWs are 40–70 nm and 10 µm, respectively. The Raman shift related to the crystallization and the amorphous SiNWs was analyzed.
Effects of Chain Length on Adhesive Force between Gold Tip and Gold Substrate Covered with Alkanethiol Self-Assembled Monolayers
Authors: Akimoto Keiko , Sato Fuminobu , Morikawa Takuya , Fujihira Masamichi
Published: February 2005

The effects of chain length on adhesive force between a gold-coated tip and a Au(111) substrate covered with alkanethiol self-assembled monolayers (SAMs) were studied. By microcontact printing (µ-CP), we prepared a patterned surface covered with two types of n-alkanethiol that have the same CH3-terminal functional group but different chain lengths. As a method for mapping adhesive force, pulsed-force-mode atomic force microscopy (PFM-AFM) was used. PFM-AFM enables the simultaneous imaging of surface topography and adhesive force. Regardless the use of the same CH3-terminal functional group to modify a surface, a difference in adhesive force corresponding to the printed pattern was observed. The adhesive force on a printed region covered with a longer alkanethiol SAM was slightly smaller than that of an unprinted region covered with a shorter alkanethiol SAM chemisorbed from solution after µ-CP. The possible molecular mechanisms for the difference in the observed adhesive force were discussed in detail.
Conductivity Measurements of Stilbene-Based Molecules Incorporated into Self-Assembled Monolayers by Conducting Probe Atomic Force Microscopy
Authors: Azehara Hiroaki , Liang Tien-Tzu , Ishida Takao , Naitoh Yasuhisa , Mizutani Wataru
Published: February 2005

We describe a technique for acquiring current-voltage (I–V) characteristics of a metal-molecule-metal junction using a conducting probe atomic force microscopy (CP-AFM) technique. To conduct a repetitive experiment efficiently, we have utilized the current imaging tunneling spectroscopy (CITS) mode of the CP-AFM system. We have prepared a self-assembled monolayer of 1-decanethiol on Au(111) substrate where 4,4'-bis(mercaptomethyl)-trans-stilbene (BMMS) molecules have been incorporated. We demonstrate that we have constructed a conductivity map derived from a set of CITS data. Conductance peaks presumably involved by BMMS molecules have been found in the conductivity map and the corresponding I–V curves have exhibited fluctuations in current. The causes of the current fluctuations are also discussed.
Observation and Manipulation of Nanostructures Formed by Rigid Rodlike Polymers
Authors: Furukawa Kazuaki , Nakashima Hiroshi , Ajito Katsuhiro , Kashimura Yoshiaki , Hu Wenping , Torimitsu Keiichi
Published: February 2005

We report on the formation of nanostructures based on rigid rodlike polymers with σ-conjugated (polysilane) and π-conjugated (poly( p-phenyleneethynylene)) electronic structures. Different types of nanostructures are formed depending on the sample preparation technique, and they are clearly visualized by atomic force microscopy (AFM). The nanostructures comprise stretched single molecular structures, nanobundle networks, and needles, all of which are induced by the intrinsic rigid nature of the polymers. We also show our attempts to manipulate these nanostructures using an AFM cantilever tip.
Noncontact Atomic Force Microscopy Investigation of Phase-Separated Alkanethiol Self-Assembled Monolayers with Different Head Groups
Authors: Ichii Takashi , Fukuma Takeshi , Kobayashi Kei , Yamada Hirofumi , Matsushige Kazumi
Published: February 2005

We investigated alkanethiol phase-separated SAMs (PS-SAMs) with different head groups using noncontact atomic force microscopy (NC-AFM). Two kinds of PS-SAMs were prepared composed of 1-dodecanethiol (C12)/3-mercapto-1-propanol (C3OH) and C12/11-mercapto-1-undecanol (C11OH). We obtained the topographic, energy dissipation, and surface potential (SP) images of each sample. All the images clearly showed the feature of phase separation. Additionally, in the case of C12/C11OH PS-SAMs, the tip-to-sample distance dependence of frequency shift (Δf) and energy dissipation were measured on each domain, which also exhibited a difference in molecular species. We discussed them in terms of the difference in the molecular arrangement, dipole moment and hydrophobic/hydrophilic properties of the head groups.
Self-Assembled Low-Dimensional Potassium Structures on GaAs(110)
Authors: Ishida Nobuyuki , Subagyo Agus , Hosoi Hirotaka , Sueoka Kazuhisa , Mukasa Koichi
Published: February 2005

We investigated the adsorption structures of K atoms on a GaAs(110) surface as a function of coverage by scanning tunneling microscopy. We found three kinds of adsorption structures, namely, the low-density linear chain, the asymmetric chain and the symmetric chain. At the initial stage with low coverage, K atoms form low-density linear and asymmetric chains. With increasing coverage, low-density linear chains disappeared and the number of asymmetric chains increased. At high adsorption coverage, K atoms began to form symmetric chains, so that the symmetric and asymmetric chains coexisted. The strong dependency of the adsorption structure on the coverage is discussed by considering a recent theoretical work.
Scanning Tunneling Microscopy Study of Imaging Change Induced by Electric Field Change of Bipyridine Derivatives in Self-Assembled Monolayers
Authors: Ishida Takao , Koyama Emiko , Tokuhisa Hideo , Belaissaoui Abdelhak , Nagawa Yoshinobu , Nakano Miki , Mizutani Wataru , Kanesato Masatoshi
Published: February 2005

We observed image changes induced by the polarity change of electric fields, by scanning tunneling microscopy (STM), for pre-assembled alkanethiol self-assembled monolayers (SAMs) embedded with small amounts of the bipyridine moiety. In the case of bipyridine dithiol molecules, STM experiments revealed that the apparent thickness of the molecular protrusions was larger under the positive bias. In this case, it was considered that the image change was caused by a conductance difference with different polarities of the tip bias. However, for the bromine-terminated bipyridine molecules, the thickness of the molecular protrusions was larger under negative bias, contrary to the case of dithiol type molecule. We considered that this image change was caused by an actual molecular conformational change because of the strong dipole moment of bromine-terminated bipyridine molecule.
Local Barrier Height of Ir/TiO2 Model Catalysts
Authors: Maeda Yasushi , Akita Tomoki , Okumura Mitsutaka , Kohyama Masanori
Published: February 2005

Iridium was deposited on TiO2(110)-(1×2) surfaces by vacuum evaporation to form Ir/TiO2 model catalysts. The local barrier height (LBH) of Ir/TiO2 was then measured using scanning tunneling microscopy (STM) and compared with that of Au/TiO2. From STM observations, it appeared that Ir was oxidized to IrO2 by annealing at 1073 K. The LBH of IrO2 particles was almost the same as that of the TiO2 substrate, while the LBH of Au particles was 0.3 eV larger. These results suggest that a charge transfer between IrO2 and TiO2 is small, and electrons are transferred from TiO2 to Au.
Scanning Force Microscopic Studies of Escherichia coli Ribosomes on Solid Substrate Surface
Authors: Matsuura Toshihiko , Kobayashi Kappei , Tanaka Hiroyuki , Matsumoto Takuya , Kawai Tomoji
Published: February 2005

Scanning force microscopy (SFM) was used to image ribosomes and ribosomal subunits isolated from Escherichia coli. Topographic images of ribosomal particles adsorbed on a mica surface were obtained directly. At 80 nM, the ribosomes aggregated. At ≤8 nM, a sparser coverage was achieved, with single ribosomes isolated from one another. Although the obtained height was significantly lower than the diameter measured by X-ray diffraction, the height histogram revealed that the observed ribosomal particles belong to three height distributions: approximately 4, 9 and 11 nm. These three distributions correspond to the 70S ribosome, and the 50S and 30S ribosomal subunits, respectively. This work demonstrates that SFM is useful in the discrimination of very small amounts of ribosomal particles on a solid substrate surface.
In Situ Atomic Force Microscopy Observation of the Desorption Process from Monomolecular Organic Layers of a Naphthalene Derivative
Authors: Miyamoto Yusuke , Nemoto Takashi , Yoshida Kaname , Kurata Hiroki , Isoda Seiji
Published: February 2005

A monomolecular crystalline layer of “1,4,5,8-naphthalene-tetracarboxylic-dianhydride” (NTCDA) on a highly oriented pyrolytic graphite (HOPG) substrate was formed by vacuum deposition. By estimating molecular packing in a crystal by scanning tunneling microscopy, a new structure of the monolayer was suggested, which is different from those reported previously. Molecules were observed to be standing perpendicular to the HOPG surface and packed in a face-to-face manner. A thermal desorption process was observed in the monomolecular layer by temperature-variable atomic force microscopy (AFM). The in situ AFM observation clarified that NTCDA molecules desorbed from the edges of crystals just above room temperature. Morphological changes at a constant temperature of 308 K were observed in detail, where desorption rates were concluded to be anisotropically dependent on crystalline edges. This dependency originated from the anisotropy of intermolecular interaction. The rate order of the desorption process, a kinetic parameter, was evaluated to be 0.2, which corresponds well to the desorption behavior observed by AFM.
Scanning Torque Microscopy
Authors: Mizoguchi Tadashi
Published: February 2005

A new type of scanning probe microscope, the scanning torque microscope (STQM), is proposed. It detects the torque exerted on magnetic moments, electric moments or electron spins on a probe tip and obtains information on microscopic local magnetic, electric or exchange fields at the scanning position on the surface of the sample. The proposed STQM measures a component of the torque by the torsion of an elastic cantilever independent from attractive or repulsive force from the sample surface. The phase shift of torsion resonance provides quantitative information on the local field at the sample surface.
Tribological Behavior of Terphenyl Self-Assembled Monolayer Studied by a Pin-on-Plate Method and Friction Force Microscopy
Authors: Nakano Miki , Ishida Takao , Numata Toshimitsu , Ando Yasuhisa , Sasaki Shinya
Published: February 2005

We investigated the friction properties of organic self-assembled monolayers (SAMs) using a pin-on-plate method, friction force microscopy (FFM) and X-ray photoelectron spectroscopy (XPS). A pin-on-plate tribometer was used for friction measurements under practical conditions. The sliding speed and load in the pin-on-plate method were higher than those of conventional FFM. Although the friction coefficients of terphenyl methane thiol SAMs measured by FFM were higher than those of soft octadecanethiol (ODT) SAMs, the friction coefficients of both the SAMs measured by the pin-on-plate method showed almost the same values. In the case of pin-on-plate measurements, the deformation of substrates may affect the friction behavior arising from the higher sliding speed in the pin-on-plate method. Furthermore, XPS measurements indicated that TP1 SAM has a higher durability against friction than ODT SAM. Therefore, we believe that terphenyl methane thiol SAM is a good candidate for a typical future lubricant.
Observation of Surface Polarization Distribution Using Temperature-Controlled Scanning Nonlinear Dielectric Microscopy
Authors: Ohara Koya , Cho Yasuo
Published: February 2005

The adsorbed water effect on the signal obtained by temperature-controlled scanning nonlinear dielectric microscopy (SNDM) is reported. From the experimental and computational results, we verified that the adsorbed water strongly affects the signal strength, depth sensitivity and resolution of SNDM. In addition, we also confirmed that the surface paraelectric layer on LiTaO3 single crystal grows with heat treatment.
Lateral Averaging Effects on Surface Potential Measurements on InAs Dots Studied by Kelvin Probe Force Microscopy
Authors: Ono Shiano , Takahashi Takuji
Published: February 2005

Surface potential measurements on InAs quantum dots (QDs) were performed using Kelvin probe force microscopy (KFM) based on noncontact-mode atomic force microscopy. By the KFM measurements, the potential distribution well corresponding to the topography was successfully observed, and the observed potential difference between the InAs QD region and the surrounding wetting layer region was nearly proportional to the QD diameter. From two-dimensional simulations, in which we calculated the appropriate tip bias to minimize the electrostatic force working between the tip and the sample, we considered that the real dependence of the potential on the QD size still existed, although lateral averaging effects on the potential measurements should be considered to explain the potential observed by the actual KFM measurements. We also pointed out that a lateral averaging effect made the observed potential contrast indistinct, particularly when the size of the nanostructure was smaller than the tip radius.
Non-Contact Atomic Force Microscopy Observation on GaAs(110) Surface with Tip-Induced Relaxation
Authors: Uehara Nobutomo , Hosoi Hirotaka , Sueoka Kazuhisa , Mukasa Koichi
Published: February 2005

We investigate the tip-sample dependence of atomically resolved non-contact atomic force microscopy (NC-AFM) images of a GaAs(110) surface taken with a tip that can resolve the tip-sample interaction originating from the dangling bonds of Ga atoms and the valence charge distribution around As atoms. Comparing the NC-AFM images taken with various tip-sample distances with a theoretical investigation of tip-sample interactions on the surface, the tip-sample interaction near the As atoms and Ga atoms are experimentally distinguished, and it is suggested that observed NC-AFM images reflect the tip induced surface relaxation.
Lens Design of Compatible Objective Lens for Blu-ray Disc and Digital Versatile Disk with Diffractive Optical Element and Phase Steps
Authors: Tanaka Yasuhiro , Komma Yoshiaki , Shimizu Yoshiyuki , Shimazaki Tomoaki , Murata Jun , Mizuno Sadao
Published: February 2005

A two-element objective lens which is compatible with for digital versatile disk (DVD) and Blu-ray Disc (BD) and has adequate optical performances in terms of off-axis wavefront and on-axis chromatic aberration for both optical heads has been designed. The first-order diffracted light is used for DVD and the second-order one is used for BD. We analyzed chromatic spherical aberration and found that using first- and second-diffracted lights causes 20 mλ/nm chromatic spherical aberration at a wavelength of 400 nm. However, using 5λ and 10λ phase steps can reduce chromatic spherical aberration to 7 mλ/nm. The designed two-element lens consists of the first plastic lens, on which there is diffractive optical element, and the second plano-convex glass molded lens.
A Neural Network Approach Based on Interference Pattern Analysis: Application to an Autoalignment Method for the Focusing Unit of NFR System
Authors: Yoon Hyoung-Kil , Gweon Dae-Gab , Lee Jun-Hee , Jeong Jaehwa , Oh Hyeong-Ryeol
Published: February 2005

From the viewpoint of assembly, evaluation results and an autoalignment method for the focusing unit (FU) of a near-field recording (NFR) system are proposed. Generally, the size of the focusing unit composed of the objective lens and the solid immersion lens is smaller than that of the conventional focusing unit. Hence there are difficulties in the precise assembly of the small focusing unit. We developed an evaluation system with an interferometer and evaluated some focusing unit samples, then a tolerance analysis of the assembly error between the SIL and the objective lens and an interference pattern analysis of the assembly error were carried out. A pattern recognition method using a neural network is presented with features, which were extracted from interference patterns due to errors in the FU.
Application of the Sliding-Mode Controller to Optical Disk Drives
Authors: Takahashi Kazuo , Tateishi Kiyoshi , Tomita Yoshimi , Ohsawa Seiichi
Published: February 2005

The Blu-ray Disc system is considered to be the next-generation optical disk system following the digital versatile disc system. The system has a high numerical aperture and a narrow track, so improved performance is needed for the servo system. A conventional pickup control based on a linear servo system is limited in the improvement of the servo performance. We have investigated a new approach to realizing high accuracy, high speed, and high robustness. One of the new servo systems is the sliding mode controller. We applied the sliding mode controller to the optical disk drive, and we proposed an effective utilization of it. We experimentally confirmed that the sliding mode controller had sufficient playability, which means trace accuracy, accessability, and defect resistance. The sliding mode controller is a promising system for realizing further playability of the high-density optical disk system.
New Tracking Servomechanism Using Phase-Shift Differential Push-Pull Method for Recordable Optical Disks
Authors: Ueyama Tetsuo , Watanabe Yukio , Numata Tomiyuki , Sakai Keiji , Horiyama Makoto , Nakata Yasuo , Kurata Yukio
Published: February 2005

We have improved the phase-shift differential push-pull (PS-DPP) tracking method with a multidivision phase-shift grating, which is applicable to various optical disks with different track pitches and does not require the accurate alignment of the three-spot position on a disk. In this paper we presented the properties of this method in recordable optical disks such as phase-change or dye media in which reflectivity greatly changes after recording. In particular, we found the cause of a radial tracking error signal offset occurring at the boundary between recorded and unrecorded tracks. To resolve this issue, we proposed two solutions: one is the optimum calculation procedure for the PS-DPP signal, and another is a newly designed phase-shift grating for recordable disks. We demonstrated the offset cancellation effect of this improved PS-DPP method using a new hologram laser unit for various types of digital versatile discs (DVDs) and showed its applicability to the Blu-ray Disc (BD).
A Low-Power Laser Driver for the Portable Blue Optical Disc Drive
Authors: Boer Bart M. de , Homberg John A. T. M. van den
Published: February 2005

A Portable Blue optical disc drive intended for application in portable devices was developed. It uses discs of only 28 mm in diameter having a capacity of 1 GB. To study the power consumption on a system level, a power model was developed, comprising the entire drive electronics. This model shows that a peak power consumption of 1 W and an average power consumption of less than 50 mW are feasible for specific applications, provided that dedicated low-power electronics is used. Therefore, a low-power laser driver was developed, which, moreover, is sufficiently flexible to allow the use of low-power write strategies. The low power consumption of the laser driver is achieved by minimising the amount of circuitry used, the supply voltages and the clock frequencies. Test silicon was produced in a 0.18 µm complementary metal oxide semiconductor (CMOS) process. The IC, with an area of 0.24 mm2, consumes 19 mW.
Effect of Stabilizer in Reducing Effects of Axial Runout on a Flexible Optical Disk
Authors: Aman Yasutomo , Onagi Nobuaki , Murata Shozo , Uchida Keisuke
Published: February 2005

We have been studying a new optical disk system constructed from a flexible disk and stabilizer. The feature of the system is the extremely small axial runout that is reduced by the aerodynamic effect of the stabilizer. We experimentally demonstrated that the system had the capability of achieving an axial runout of less than 5 µm across a radial region from 35 to 55 mm at a linear velocity of 13 m/s.
A New Run-length-limited (2,7) Parity Preserving Code Limiting the Repeated Minimum Transition Run for Optical Storage Systems
Authors: Hong Hyunsun , Lee Jaejin
Published: February 2005

In this paper, a new run-length-limited (RLL) (2,7) parity preserving (PP) repeated minimum transition run (RMTR) 4 code is proposed. The proposed code shows better performance in terms of density ratio, RMTR, DC component suppression, flexible adaptation for a partial response maximum likelihood (PRML) [1] system and bit error rate (BER) as compared with (2,10) code [2] (currently applied in storage systems) or (1,7) PP code [3] (highly recommended for next-generation optical recording systems). On the basis of the results of experiments on optical storage systems, the superiority of the proposed code is established.
Front Surface Recording Reliability Studies
Authors: Jr. Bernard W. Bell , Blankenbeckler David L. , Howe Dennis G. , Lee Lane W.
Published: February 2005

The data reliability of a front surface optical recording system using a 32 mm disk is demonstrated. The system has approximately the same areal density as the digital versatile disk (DVD) system but utilizes an enhanced error correction coding (ECC) architecture. Theoretical statistical error analysis of the ECC subsystem shows a significantly reduced mis-correction probability. Experimental results from laboratory smoke and dust contamination studies as well as real world experiments performed in an office, a smoky bar, and a greasy kitchen environment are discussed and confirm the robust performance of the system predicted by the theory.
Two-Dimensional Optical Storage
Authors: Lee Alexander van der , Bruls Dominique , Busch Christopher , Immink Andre , Coene Wim , Hekstra Andries
Published: February 2005

Two-dimensional optical storage aims at increasing the data capacity and data rate for a given physical read-out system. It uses parallel read-out in combination with advanced signal-processing. Experimental results results on read only memory (ROM) discs are presented that proof the concept. Laser beam recorded discs proof the concept, and electron beam recorded disc show the feasibility at real physical parameters for a density at 35 GB with ample tilt margins.
Evaluation of Multilayered Waveguide Holographic Memory Media
Authors: Ishihara Kei , Fujiwara Tsuyoshi , Esaki Akira
Published: February 2005

A multilayered waveguide holographic memory media consists of a stack of single-mode slab waveguides. An UV embossing process has been developed for fabricating this structure. This process is suitable for mass production at low cost, but it is has a disadvantage of poor precision in the control of layer thickness and data position. The distribution of the core inclination and the error in data position alignment were checked, and the results showed that this process is sufficiently accurate for fabricating the above media. Also, the durability of the media fabricated by the UV embossing process was tested. The media was preserved under high-temperature and high-humidity conditions (80°C and 85%RH respectively). The results showed that this media has sufficient durability for practical use.
Signal Characteristics of Super-Resolution Near-Field Structure Disk in Blue Laser System
Authors: Kim Jooho , Hwang Inoh , Kim Hyunki , Yoon Duseop , Park Insik , Shin Dongho , Park Yunchang , Tominaga Junji
Published: February 2005

We report the signal characteristics of a super-resolution near-field structure (super-RENS) disk in a blue laser system (laser wavelength, 405 nm; numerical aperture (NA), 0.85). By introducing a new structure for the blue laser system, a 42.5 dB carrier to noise ratio (CNR) at a 50-nm-mark-length-signal (which is equivalent to a 75 GB capacity with a 0.32 micrometer track pitch and a 1–7 modulation code (Blu-ray disc (BD) format)) and a much higher readout-stability were obtained. Transmission electron inicroscope (TEM) image analysis revealed that the new blue structure has clear diffusion protection barriers produced by continuous Pt particles, which is related to higher CNR and readout stability characteristics.
High Resolution Readout Using a Near-Field Optical Probe Embedded in a Condensed Lens
Authors: Kojima Naoto , Mishima Akio , Watanabe Kenjiro
Published: February 2005

We have developed a novel head structure with an embedded near-field optical probe in a solid immersion lens system. This head structure is suitable for optical probe detection using Scanning Interferometric Apertureless Microscope (SIAM) technology. We fabricated a hemispherical lens with an embedded near-field optical probe. The dielectric coupling between probe and medium generates a signal beam with a scattered field which results in a small phase shift. We can observe the surface features of the medium by detecting the degree of phase. In this way, periodic signals from lands shorter than the optical cutoff can be detected. The signal intensity decreases to 1/e2 with a spacing of 60 nm. The detected signals are generated by the near-field optical probe.
Shift Selectivity and Hologram Playback Margin Dependence on the Average Speckle Size of a Randomly Phase Encoded Reference Beam
Authors: Yamatsu Hisayuki , Baba Shigeyuki , Kihara Nobuhiro
Published: February 2005

Several important hologram reconstruction parameters of shift multiplexing with a randomly phase encoded reference beam were investigated as functions of the reference beam average speckle size at the medium. Those are shift selectivity, reference beam defocus margin, and medium tilt margin. It was confirmed that these parameters are linearly dependent on the average speckle size in certain directions. The exception was the in-track direction medium tilt margin which is dominated by the Bragg matching condition. We found that smaller average speckle size is preferable in view of achieving higher recording density, while larger average speckle size is desirable in view of having wider playback margins. Based on the experimental results, the multiplexing of 300 holograms per unit area was demonstrated with a polymer medium with sufficiently low bit error rates.
Media Technologies of 20 GB Single-Layer Rewritable Phase-Change Disc for HD DVD System
Authors: Ohmachi Noritake , Ashida Sumio , Yusu Keiichiro , Nakai Tsukasa , Ichihara Katsutaro , Nakamura Naomasa
Published: February 2005

Sufficient signal amplitude, erase ratio and low amount of cross-erase must be attained to achieve higher recording capacity of rewritable phase-change media. We have developed new media technologies, such as the GeTe-rich GeTe-Sb2Te3 pseudobinary alloy recording film partially substituted with bismuth and an additional layer to control thermal diffusion. The recording layer material enables a high erase ratio with a high signal amplitude. The additional layer also reduces the amount of cross-erase while maintaining a sufficient erase ratio. We have successfully demonstrated rewritable phase-change media having 20 GB capacity by using these media technologies for the HD DVD system with a blue-violet laser diode having the wavelength of 405 nm, a numerical aperture of the objective lens of 0.65 and light incident on a 0.6-mm-thick substrate. In this paper, we describe our new media technologies and the evaluation results, such as tilt margins, uniformity, overwriting cyclability and life durability.
Inorganic Write Once Media
Authors: Chen Bing-Mau , Chen Hung-Fa , Yeh Ru-Lin , Chung Jei-ming
Published: February 2005

A write-once disk with AlSi alloy was proposed and studied. A jitter of 6.5% and a modulation of larger than 0.8 were obtained at a linear velocity of 8.4 m/s. Jitter is less than 5% in the blue laser system at a clock frequency of 66 MHz and a linear speed of 8.25 m/s for track pitch of 0.68 and 0.45 µm disk.
Nonlinear Optical Properties of the Au-SiO2 Nanocomposite Superresolution Near-field Thin Film
Authors: Fu Yuan Hsing , Ho Fu Han , Hsu Wei-Chih , Tsai Song-Yeu , Tsai Din Ping
Published: February 2005

A Au-SiO2 superresolution nanocomposite active nonlinear optical thin film is fabricated reproducibly by cosputtering method with the size of Au nano particles around 2 to 10 nm. Results of the Z-scan indicate that these nanocomposite Au-SiO2 films have nonlinear optical properties and enhanced transmittance at the focusing position. For a 15-nm-thick Au-SiO2 nanocomposite thin film, the transmittance can be 135% for a sample with an average grain size of around 5 nm.
Substrate Deformation Studies on Direct Overwriting of Phase-Change Rewritable Optical Disc with Germanium Nitride Interface Layers
Authors: Tan P. K. , Shi L. P. , Miao X. S. , Meng H. , Wong K. P. , Lim K. G. , Chong T. C.
Published: February 2005

The deformation of polycarbonate substrate during direct-overwriting (DOW) process of phase-change (PC) optical disc with germanium nitride (Ge-N) interface layers was studied. From scanning probe microscopy (SPM) results, the deformation of the land/groove caused by thermal energy during the writing process was highly reduced by the Ge-N interface layers. The Ge-N interface layers not only prevent sulfur atom diffusion into the PC layer during DOW, but also protect the substrate from thermal damage. Therefore, the optical disc with Ge-N interface layers achieved DOW cycles 2 orders higher than that of the conventional rewritable disc. The substrate deformation lifetime during the DOW process was multiplied by approximately 100 times.
Process for Developing Recording Materials of Phase Change Optical Media Using MediaTest-I and Simulation Technique
Authors: Mori Rie
Published: February 2005

The method for investigating temperature-dependent crystallization characteristics by using MediaTest-I and a simulation technique was established. Our method is able to evaluate materials that nucleate easily as well as those that do not, and is also able to evaluate both the crystal growth and nucleation properties. The recording material in compact disc rewritable 4 times speed (CD-RW4×), a material of the SbTe system and the materials of the GaSb system were investigated using this method, and its effectiveness was confirmed. Additionally, it was found that the crystal growth rate of GaSbInSn reaches 10 times that of the recording material in CD-RW4× if its Ga:Sb and In:Sn ratios are adjusted appropriately.
High-Speed 16× Digital Versatile Disk Dye Recording
Authors: Hellmig Jochen , Rijpers Jan C. , Spruit Hans
Published: February 2005

In dye-based optical recording, thermal interference is a major obstacle for high recording speeds. Detailed studies of recorded data reveal that post-heat from writing of a pit can result in unwanted shrinkage of the previously written pit. To prevent pit shrinkage we apply a castle-type writestrategy. We demonstrate digital versatile disk (DVD) recordings at 16× speed, 1× and intermediate speeds.
Manufacture of 27 GB Read-Only-Memory Disc Using Deep-UV Beam Recorder with Two-Dimensional Optical Compensation
Authors: Yoshioka Terufumi , Chika Yuzuru , Adachi Kazuyoshi , Sugiyama Toshinori , Kiyono Kenjiro , Nagai Tadakazu
Published: February 2005

A novel mastering method using a deep-UV laser beam recorder (LBR) with two-dimensional optical compensation has been proposed. Using this technique, uniform fine pits can be created. The result reveals that a 27 GB read-only-memory (ROM) disc can be realized. The bottom jitter with a limit equalizer was 7.5%.
Progress in Electron Beam Mastering of 100 Gbit/inch2 Density Disc
Authors: Takeda Minoru , Furuki Motohiro , Yamamoto Masanobu , Shinoda Masataka , Saito Kimihiro , Aki Yuichi , Kawase Hiroshi , Koizumi Mitsuru , Miyokawa Toshiaki , Mutou Masao , Handa Nobuo
Published: February 2005

We developed an electron beam recorder (EBR) capable of recording master discs under atmospheric conditions using a novel differential pumping head. Using the EBR and optimized fabrication process for Si-etched discs with reactive ion etching (RIE), a bottom signal jitter of 9.6% was obtained from a 36 Gbit/inch2 density disc, readout using a near-field optical pickup with an effective numerical aperture (NA) of 1.85 and a wavelength of 405 nm. We also obtained the eye patterns from a 70 Gbit/inch2 density disc readout using an optical pickup with a 2.05 NA and the same wavelength, and showed almost the same modulation ratio as the simulation value. Moreover, the capability of producing pit patterns corresponding to a 104 Gbit/inch2 density is demonstrated.
Acid-Breakable Resin-Based Chemical Amplification Positive Resist for Electron-Beam Mastering: Design and Lithographic Performance
Authors: Sakamizu Toshio , Shiraishi Hiroshi
Published: February 2005

A positive chemical amplification resist based on acid-catalyzed fragmentation of acetal groups in its main chain has been developed as a means of reducing line-edge roughness. The resist consists of an acid generator, an acid-diffusion controller and an acid-breakable (AB) resin that is synthesized through a co-condensation reaction between polyphenol and aromatic multifunctional vinylether compound. The effects of the fractionation of AB resins on resin properties and line-edge roughness (LER) are evaluated. Although AB resins have wide molecular weight distributions, the density of acetal groups in this AB resin is found to be almost constant except in the lower molecular weight components. The resist with a fractionated resin from which such components are removed provides high-resolution patterns (70-nm-wide pit) with fairly low LER. AFM analysis shows that the surface roughness (SR) of the resist with the fractionated resin is smaller than that of a resist using nonfractionated AB resin, and that the SR value is not altered throughout the range of exposure doses up to just below the start of dissolution. By using the fractionated AB resin, the AB resin-based resist (ABR) is capable of forming sub-100 nm L/S patterns with less than 5 nm of LER (3σ).
Improvement of Electron Beam Mastering Using Dry Etching Process
Authors: Kasono Osamu , Sato Megumi , Sugimoto Tatsuya , Kojima Yoshiaki , Katsumura Masahiro
Published: February 2005

We have developed an electron beam recorder and utilized it in high-density disk mastering. We discussed an electron scattering in disk mastering that degrades the reproduction performance of disks. In order to improve the reproduction performance, we applied a dry etching process to the disk mastering process, and confirmed its efficacy in reducing the scattering effect and improving disk noise by calculation and experiments. We fabricated `Blu-ray Disc'-type read-only memory disks with and without the dry etching process, and noticed the advantage of the dry etching process from the jitter comparison. Finally, a 4.7% jitter was achieved in a 25 GB capacity disk, while a 5.7% jitter was obtained in a 27 GB capacity disk with additional recording compensation.
1×8 Cascaded Multimode Interference Splitter in Silicon-On-Insulator
Authors: Wang Zhangtao , Fan Zhongchao , Xia Jinsong , Chen Shaowu , Yu Jinzhong
Published: February 2005

A cascaded multimode interference 1×8 power splitter is proposed and fabricated in silicon-on-insulator material. The device consists of seven 1×2 power splitters arranged in a tree configuration. The cascaded splitter and its 1×2 splitter element have the power uniformity of approximately 1.5 dB and 0.3 dB, respectively.
Subgap Optical Absorption Studies in Boron Implanted Silicon
Authors: Mathew Alex , Madhusoodanan Kottarath Naduvil
Published: February 2005

Effect of light ion implantation in Si is studied using B+ ion implantation. The subgap optical absorption measurement by photothermal deflection spectroscopy (PDS) is used for the investigations. The subgap absorption is measured as a function of ion dose and substrate temperature. The magnitude of optical absorption, divacancy concentration and inverse logarithmic slope E
0 obtained from absorption measurements are used for analyzing the results. It is found that the 300 K implanted samples do not undergo amorphization even at a dose of 1×1016 cm-2. In the case of 80 K implanted sample, amorphization occurs at a dose of ≈1015 cm-2. The dose and temperature dependence of the above parameters and their annealing induced changes are discussed in terms of the nature and evolution of defects in the case of a light ion like B+ implantation in Si.
Amorphous/Microcrystalline Silicon Thin Film Transistor Characteristics for Large Size Oled Television Driving
Authors: Tsujimura Takatoshi
Published: February 2005

An amorphous silicon thin film transistor (TFT) and a TFT with a microcrystalline/amorphous channel layer are studied for organic light emitting diode (OLED) backplane usage. The amorphous silicon TFT V
TH shift can be reduced with saturation region operation. There are two mechanisms that cause the V
TH shift in a saturation region: One that appears with continuous current flow and the other that appears with the transient charge injection into a gate insulator. SiH4 flow in hydrogen plasma with a pumping flow period shorter than the gas residence time produces a high-transconductance microcrystalline/amorphous silicon TFT.
Characterization of Carrier Concentration and Mobility in n-type SiC Wafers Using Infrared Reflectance Spectroscopy
Authors: Narita Katsutoshi , Hijikata Yasuto , Yaguchi Hiroyuki , Yoshida Sadafumi , Nakashima Shinichi
Published: February 2005

We have estimated the free-carrier concentration and drift mobility in n-type 6H-SiC wafers in the carrier concentration range of 1017–1019 cm-3 from far- and mid-infrared (30–2000 cm-1) reflectance spectra obtained at room temperature. A modified classical dielectric function model was employed for the analysis. We found good agreement between the electrical properties derived from infrared reflectance spectroscopy and those derived from Hall effect measurements. We have demonstrated the spatial mapping of carrier concentration and mobility for commercially produced 2 inch SiC wafers.
Junction Leakage Generation by NiSi Thermal Instability Characterized Using Damage-Free n+/p Silicon Diodes
Authors: Tsuchiaki Masakatsu , Ohuchi Kazuya , Hongo Chie
Published: February 2005

Using n+/p junctions formed by solid phase diffusion, a clear correlation between junction leakage and NiSi thermal instability was readily established. After forming an NiSi layer on damage-free junctions, various post-annealing processes at around the silicidation temperature were applied. A consistent and systematic rise of the leakage level was observed with the increase of the annealing time and the temperature. The migration of the released Ni atoms away from the NiSi layer, the subsequent clustering of the migrant Ni atoms, and the eventual formation of generation-recombination centers deep inside the Si substrate were identified as the basic components of the principal leakage mechanism. Detailed analysis of the thermally stimulated ingressive movement of the leakage-depth profiles revealed a substantial Ni burst at an early stage of annealing. This anomalous Ni burst imposes severe restrictions on junction shallowing for NiSi technology and sets a strict upper limit on the allowable process temperature for effective leakage suppression.
Body-Charge-Induced Switching Characteristics in Fully Depleted Silicon-on-Insulator Digital Circuits
Authors: Sato Yasuhiro , Ishihara Takako , Kado Yuichi , Nishimura Kazuyoshi , Tsuchiya Toshiaki
Published: February 2005

Switching characteristics of digital circuits built with fully depleted (FD) silicon-on-insulator (SOI) metal–oxide–semiconductor field effect transistors (MOSFETs) are experimentally investigated. The results show that the switching speed depends on the input-signal frequency even in FD SOI digital circuits, though FD SOI MOSFETs are expected to suppress floating body effects. The switching becomes faster as the input-signal frequency decreases. This is because the body charge dynamically changes during the switching even in FD SOI MOSFETs. FD SOI MOSFETs have no neutral region in the body, while partially depleted (PD) MOSFETs do. Therefore, impact ionization plays a major role in changing the body charge in FD SOI MOSFETs, while charge redistribution does in PD SOI MOSFETs. The accumulation of majority carriers generated by impact ionization increases the body charge, and thus thereshold voltage decreases, which causes an excess drain current. This excess current is the reason for the faster switching in FD SOI digital circuits. Since the impact ionization efficiency decreases as the supply voltage decreases, the dependence of propagation delay time, t
pd, on the input signal frequency can be largely reduced for FD SOI digital circuits. We also discuss several ways to efficiently decrease majority carriers accumulated in the body region and thereby minimize the dependence of t
pd on the input-signal frequency for FD SOI digital circuits.