bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Hydrogen Emission in Laser Plasma Induced by Focusing Fundamental Q-sw YAG Laser on Solid Samples
Authors: Idris Nasrullah , Kurniawan Hendrik , Lie Tjung Jie , Pardede Marincan , Suyanto Hery , Hedwig Rinda , Kobayashi Takao , Kagawa Kiichiro , Maruyama Tadashi
Published: February 2005

Hydrogen emission has been studied in laser plasma by focusing a Nd-YAG laser (1,064 nm, 50 mJ, 8 ns) on various types of samples, such as copper plate, zinc plate and glass plate. Several parameters influencing the emission were varied, such as the type of gas (air, nitrogen and helium), gas pressures (ranging from 2 up to 760 Torr) and laser power density. It was found that Hα emission with a narrow spectral width occurs with high efficiency when the laser plasma is produced in the low-pressure region. It was also confirmed that the conventional well-known laser-induced breakdown spectroscopy (LIBS), which usually carried out at atmospheric air pressure, cannot be applied for the analysis of hydrogen as impurity. This specific characteristic of the pressure dependence of hydrogen is interpreted based on our shock wave model, taking account of the fact that the hydrogen mass is extremely light compared to that of the host elements.
Dependence of Fiber Bragg Grating Characteristics on its Length
Authors: Ando Maki , Yamauchi Makoto , Nakayama Keisuke , Moriyama Kenji , Fujita Keio , Masuda Yuji , Kimura Masanori , Mizutani Yasuo , Kimura Susumu , Yokouchi Takashi , Suzaki Yoshifumi , Nakagawa Kiyoshi , Ejima Seiki
Published: February 2005

A fiber Bragg grating (FBG) is normally made with a length of 10 to 30 mm. Depending on the application, however, a short length may be desired, especially in sensor applications for local detection. Under the most common fabrication conditions using the phase mask method, we have fabricated FBGs with lengths ranging from 0.35 to 15 mm using different excimer laser irradiation times. Although 0.35-mm-long FBGs can be made with laser exposure times exceeding 1 h, the practical minimum FBG length appears to be around 3 mm with exposure times in the range of 3 to 5 min.
Dynamical Behavior of a Ferroelectric Liquid Crystal with Monotropic Transition Temperatures during Electric-Field-Induced Switching Studied by Time-resolved Infrared Spectroscopy Combined with Singular Value Decomposition
Authors: Zhao Jinggang , Ozaki Yukihiro
Published: February 2005

The switching dynamics of a ferroelectric liquid crystal (FLC-154) with monotropic transition temperatures has been explored under the surface-stabilized states by polarized infrared (IR) absorption and time-resolved IR spectroscopy. The polarized IR and time-resolved IR studies have revealed that FLC-154 shows significantly different dynamics from FLCs with non-monotropic thermotropic transition temperatures. The analysis of the relative orientation of the transition moments of the CH2 symmetric and antisymmetric stretching modes has suggested that the alkyl chains of FLC-154 take a gauche-trans-gauche conformation. It has also been revealed from the same analysis that the alkyl chains take different alignment under dc applied voltages of 20 V of both polarities at 65°C. Time-resolved IR spectra of FLC-154 in a planar-aligned cell were measured as a function of the polarization angle ranging from 0° to 180° under a rectangular electric field of ±20 V with a 5 kHz repetition rate in the smectic-C
* (Sm-C
*) phase at 65°C. These spectra have enabled us to explore the reorientation processes of the alkyl chains, the core and the large C=O dipole moments of FLC-154 at all the delay times. The singular value decomposition (SVD) was applied to the time-resolved IR spectra in the 3020–1000 cm-1 region of FLC-154. The results of SVD have provided information about the profile of the principal component (PC) score versus the delay time, enhancing the ability of time-resolved IR in probing the switching dynamic. It has been found from the SVD analysis that the average orientation of a large C=Obiphenyl dipole moment (it arises from the C=O group adjoining the biphenyl ring) of FLC-154 is unchanged during the whole electric-field-induced switching. It seems likely that the core of FLC-154 straddles the polyimide molecules on the surface of the FLC layer. This configuration of FLC molecule forces the transverse C=Obiphenyl dipole moment to be parallel with the rubbing direction, and the molecules of FLC-154 revolve around the average orientation of the C=Obiphenyl dipole moment. These results have suggested that the FLC-154 molecules revolve around the large C=Obiphenyl dipole moment during the electric-induced-field switching. The dynamic SVD profile for the alkyl chains, a large C=Ochiral dipole moment (it arises from the C=O group in the chiral moiety) and the core moiety have shown that all the moieties require an induction period of 10 µs before responding to the electric field.
Tungsten Silicide and Germanide Growth and Metal Interface
Authors: Okuno Kimio , Horio Junya
Published: February 2005

Silicide and germanide growth and the internal diffusivity of silicon and germanium atoms into a tungsten substrate have been studied by atomic capability field ion microscopy (FIM). The silicon-tungsten interface is highly reactive on heating above 850 K and tungsten silicide is easily formed, whereas tungsten and germanium are comparatively less reactive. Although the reaction depth range of silicidation is three atomic layers of the tungsten substrate, the reaction depth of tungsten silicide locally differs at T=950–1000 K. This phenomenon is particularly favorable on and around the W{111} plane and boundary along W(111), W(011) and W(111) which is caused by independently growing silicide on W(001) plane areas. The chemical combination between tungsten and germanium atoms is limited at the top layer of the W substrate. Almost no internal diffusion of germanium into the substrate tungsten occurs. The growth mode of the W silicide and W germanide intrinsically differs. The value of the work function at various silicide and germanide coverages was also evaluated.
Surface Electrical Conduction measurement of Si (100) film of Silicon-on-Insulator wafers
Authors: Kamiyama Eiji
Published: February 2005

This paper discusses an investigation into the surface electrical conduction of Si(100) film in the Silicon-on-Insulator (SOI) wafer. Controlling the gate voltage of the so-called `pseudo-MOSFET', which is a kind of MOSFET and in which the gate voltage is applied to the substrate of SOI wafers, can reduce the contribution from conduction inside the silicon film. The drain current and the resistivity of the silicon film were measured at the cut-off region in drain current–gate voltage (I
d–V
g) characteristics of the pseudo-MOSFET. The experiment shows that the drain current at this region of the HF-treated sample becomes much higher than that of one before HF treatment. Compared with a calculated approximation, this high drain current cannot be explained by the existence of the inversion layer caused by the pinning at the silicon film surface. Hence, it must be due to the surface electrical conduction.
Low-Friction and Long-Life Solid Lubricant Films Structured of Nanoperiod Tungsten Disulfide and Molybdenum Disulfide Multilayer
Authors: Miyake Shojiro , Sekine Yukio , Noshiro Junichi , Watanabe Shuichi
Published: February 2005

To reduce friction coefficient, hardness is increased by using a nanometer-period multilayer structure and shearing strength is decreased by applying of low-shearing-strength tungsten disulfide and molybdenum disulfide layers. In nanoindentation testing, multilayer films showed a higher hardness and a lower modulus of dissipation energy than single-layer films. In nanoscratch and microwear testing using an atomic force microscope (AFM), both the scratching force and wear rate of multilayer films could be decreased. The friction coefficient of the nanoperiod multilayer film was as low as µ=0.04 in the ball-on-disk tribotest in 52 to 58% humidity conditions. The friction endurance life of the nanoperiod multilayer films evaluated from the cycles in which the friction coefficient increases rapidly is nine times longer than those of single-layer films.
Electron Beam Lithography on Organosilane Self-Assembled Monolayer Resist
Authors: Tanii Takashi , Hosaka Takumi , Miyake Takeo , Ohdomari Iwao
Published: February 2005

We report a result of a feasibility study on the application of an octadecyltrimethoxysilane self-assembled monolayer to a resist film for electron beam lithography. The self-assembled monolayer deposited on a silicon dioxide surface by chemical vapor deposition is resistant to both sulfuric acid and hydrofluoric acid. By immersing the electron-beam-irradiated surface into both acids, we successfully develop microstructural patterns in the self-assembled monolayer. In particular, we show the effectiveness of immersing the substrate into a sulfuric-acid-based solution for the development of the pattern. The relationship between the required dose and the developing time is estimated by measuring the morphology of the developed patterns by atomic force microscopy. The pattern in the self-assembled monolayer can be transferred into both the underlying silicon dioxide layer and the silicon substrate. These results indicate that the organosilane self-assembled monolayer serves as an alternative resist for electron beam lithography.
The Temperature Coefficient of Frequency and Quality Factors at Resonance and Antiresonance Frequencies of Infinite Interdigital Transducers for Leaky Surface Acoustic Waves on a SiO2/IDT/36° Y–X LiTaO3 Substrate
Authors: Hasegawa Koji , Sakuma Masayasu
Published: February 2005

The temperature coefficient, electromechanical coupling coefficient and quality factors at resonance frequencies of infinite interdigital transducers (IDTs) for leaky or nonleaky surface acoustic waves on SiO2/IDT/36° Y–X LiTaO3 are presented. The electrode materials of IDTs with aluminum, copper, gold, silver, tantalum, titanium or tungsten alloy are examined. Using the hybrid Trefftz finite element method, the radiation conditions of leaky surface acoutic waves are rigorously taken into account in the presented results. Computed values reveal that silver electrode IDTs with a SiO2 film thickness of 0.36p and an electrode height of 0.2p have an electromechanical coupling coefficient of 0.035 and a temperature coefficient of frequency of -10 ppm/°C, where p is the period of IDT fingers.
Concentration and Injection of Long Deoxyribonucleic Acid Molecules at the Interface of Micro- and Nano-channels
Authors: Ueda Masanori , Takamura Yuzuru , Horiike Yasuhiro , Baba Yoshinobu
Published: February 2005

Using micro- and nano-fabricated channels, we investigated the concentration effects and injection processes of long deoxyribonucleic acid (DNA) molecules under hydrodynamic flow. Depending on the applied pressure, we observed a transition from concentration to permeation of long DNA molecules at the interface of micro- and nano-channels. Critical pressures differed according to the depth of the channel.
Crystallization of Monodisperse Lead Zirconate Titanate Nanoparticles Produced by Laser Ablation
Authors: Katagiri Takahiro , Seol Kwang Soo , Takeuchi Kazuo , Ohki Yoshimichi
Published: February 2005

Monodisperse lead zirconate titanate (PZT) nanoparticles with diameters of 9 nm were produced by laser ablation followed by a gas-phase thermal treatment in combination with a size-classification technique using a very low-pressure differential mobility analyzer. The particles prior to the thermal treatment are amorphous. When the laser power density for ablation increases from 0.5 GW/cm2 to 12 GW/cm2, the production yield of the particles increases regardless of the laser photon energy. When the laser photon energy is 3.5 eV, the nanoparticles generated with laser power densities as high as 7 GW/cm2 are crystallized to perovskite by thermal treatment at 900°C, while those generated with even higher power densities become pyrochlore. In contrast, when the laser photon energy is 2.3 eV, perovskite nanoparticles are obtained only at a power density of 0.5 GW/cm2. These results reveal that the crystalline structure of PZT nanoparticles can be adjusted to perovskite or pyrochlore by changing thermal treatment temperature, laser power density, and photon energy. Furthermore, X-ray photoelectron spectroscopy indicates that the crystallization to pyrochlore is caused by lead deficiency.
Large-Scale Hierarchical Organization of Nanowires for Functional Nanosystems
Authors: Whang Dongmok , Jin Song , Lieber Charles M.
Published: February 2005

We review recent studies of solution-based hierarchical organization of nanowire building blocks. Nanowires have been aligned with controlled nanometer to micrometer scale separation using the Langmuir-Blodgett technique, transferred to planar substrates in a layer-by-layer process to form parallel and crossed nanowire structures over centimeter length scales, and then efficiently patterned into repeating arrays of controlled dimensions and pitch using photolithography. The hierarchically-organized nanowires open up key opportunities in several general areas of nanoscale science and technology. First, hierarchically-assembled nanowire arrays have been used as masks to define nanometer scale metal lines and surface features over large areas. Second, hierarchically-assembled nanowire arrays have been used to fabricate fully-scalable centimeter size arrays of field-effect transistors in high yields without requiring alignment of individual nanowires to output electrodes. Diverse applications of this approach for enabling a broad range of functional nanosystems, including macroelectronic and sensing applications, are described.
Scanning Probe-Based Chemical Conversion of Organic Monolayers
Authors: Sugimura Hiroyuki
Published: February 2005

Atomic force microscopy (AFM) has been applied to localized surface chemical conversion of organosilane self-assembled monolayers (SAMs). Current was injected from a conductive AFM probe into a SAM in order to induce electrochemical reactions of the SAM in the presence of adsorbed water. Two examples were demonstrated. First was oxidation of an alkylsilane SAM. Modification processes were dependent on the operation mode of AFM, that is, contact, intermittent-contact and noncontact modes. In the contact mode, the alkylsilane SAM was decomposed and removed from the substrate Si accompanied with anodization of Si, while in the intermittent-contact mode, methyl groups terminating the SAM were converted to carboxyl groups without causing any changes on the main part of the SAM and the substrate Si. In addition, no modification was induced when the noncontact mode was used. The next example was oxidation and reduction of an amino-terminated SAM in a reversible manner. Oxidation of amino groups on the SAM to nitoroso groups and their reduction back to amino groups were successfully conducted by the current-injecting AFM in the contact mode while applying positive and negative sample biases, respectively. This process could be repeated several times.
Investigation of the Interaction of Hydrogen with a Nb(100) Surface by Scanning Tunneling Microscopy
Authors: An Bai , Zhang Lin , Wen Mao , Fukuyama Seiji , Yokogawa Kiyoshi , Yoshimura Masamichi
Published: February 2005

The surface structures of Nb(100) are investigated during hydrogen uptake at room temperature and subsequent heating in an ultrahigh vacuum (UHV), at elevated temperatures of up to 700 K by scanning tunnelling microscopy (STM). Clusterlike structures of niobium hydride are gradually formed on the (1×1) Nb(100) surface structure due to exposure to more than 8 L of hydrogen at room temperature. The hydride clusters disappear and small (1×1) structure patches are formed on the surface after continued heating to above 450 K in UHV. The interaction of hydrogen with a Nb(100) surface during hydrogen uptake is discussed.
Wide-Range Scanning Probe Microscopy for Visualizing Biomaterials in the Submillimeter Range
Authors: Mizutani Takeomi , Haga Hisashi , Nemoto Koji , Kawabata Kazushige
Published: February 2005

We developed wide-range scanning probe microscope (WR-SPM) for visualizing the topography and mechanical properties of samples in the submillimeter range. A piezoelectric scanner with a maximum x
y scan range of 400 µm square and a z range of 16 µm was constructed by joining two commercial piezotranslators in tandem. The reliability of measurement was confirmed by measuring a well-defined pattern engraved on a silicon substrate. Using the WR-SPM, the spatial distribution of stiffness and time-lapse images of a large colony consisting of approximately 40 epithelial cells were visualized successfully, where the local stiffness was measured using the force mapping mode. These results indicate that the WR-SPM can be a powerful instrument to visualize the mechanical properties of biological phenomena extending in the submillimeter range.
Observation of Etch Figures on Protein Crystals by Atomic Force Microscopy
Authors: Hondoh Hironori , Nakada Toshitaka
Published: February 2005

Etch figures on the (110) face of hen egg white lysozyme crystals in aqueous solution were investigated by atomic force microscopy. Three types of etch pits with flat, “deep” flat and point bottoms were observed. All etch pits are elongated to the [-110] direction, similar to the growth of 2D islands. The etch pit density of contaminated crystals, fabricated from a widely used commercial sample, was approximately ten times greater than that of pure crystals. Moreover, the density of “deep” flat bottom pits on contaminated crystals increased with supersaturation, while their density on pure crystals remained almost constant. These results suggest that the impurity molecules incorporated during growth and the line defects, such as edge dislocations, induced by the molecules are the dominant defects in lysozyme crystals grown from commercially available samples.
Adlayer of Naphthalene on Rh(111) Studied by Scanning Tunneling Microscopy
Authors: Inukai Junji , Wakisaka Mitsuru , Itaya Kingo
Published: February 2005

An adlayer of naphthalene was formed on Rh(111) by vapor deposition. The low-energy electron diffraction analysis showed the adlayer having a (3 ×3) structure. Using a scanning tunneling microscope, individual naphthalene molecules were observed to lie flat on the surface. The C2 axes of the molecules were found to be aligned in the directions of the atomic rows of the Rh substrate.
New FM Detection Techniques for Scanning Probe Microscopy
Authors: Kobayashi Dai , Kawai Shigeki , Kawakatsu Hideki
Published: February 2005

New FM demodulation techniques capable of detecting the fast frequency deviation of a cantilever of a noncontact atomic force microscope are proposed and their features were demonstrated by experiments. The techniques entail the frequency conversion of an input FM signal to a pair of zero-Hz-centered signals with a mutual phase difference of 90 deg, differentiation or Hilbert transformation, multiplication and subtraction. Since the center frequency and scale factor are determined by different processes, a high sensitivity, a fast response and a precise center frequency are achievable at the same time. The developed circuitry is capable of detecting a minimum frequency shift of 0.1 Hz. The maximum response bandwidth is 100 kHz.
Scanning Tunneling Microscopy Barrier Height Imaging of Subsurface Dopant Atoms on Hydrogen-Terminated Si(111)
Authors: Kobayashi Kengo , Kurokawa Shu , Sakai Akira
Published: February 2005

Dopant atoms beneath a hydrogen-terminated Si(111) 1×1 surface are investigated by scanning tunneling microscopy (STM) and barrier height (BH) imaging. Because of the weak screening effect of the hydrogen-terminated Si(111) surface, subsurface donors and acceptors can be imaged by STM. From BH images, we can deduce a local change in BH at subsurface dopant sites. Both the sign and magnitude of the observed BH change are in good agreement with calculations assuming a screened Coulomb potential for a dopant potential.
Photoresponse of Titanium Dioxide Surface on Atomic Scale: Site for Visible Light Absorption
Authors: Komiyama Masaharu , Li Yan-Jun
Published: February 2005

The local photoresponse of a rutile TiO2(110) surface was visualized on the atomic scale by scanning tunneling microscopy (STM). Almost all the areas on the (110) surface responded to the illumination of 325 nm ultraviolet (UV) light, in accordance with the minimum bulk band-gap (3.2 eV) electron transition, with steps and (1×2) ridge areas exhibiting higher response intensities. When the same surface was illuminated with blue light at 442 nm, which is well below the minimum bulk band-gap transition energy, most of the surface areas were dormant, but certain areas at step regions and (1×2) ridge structures responded to the blue light. These sites are associated with oxygen deficiency on the surface, which may give a clue to the possibility of the surface engineering of a titania photocatalyst to be employed under visible light.
Growth of Nanopucks on Pb Quantum Islands
Authors: Lin H. Y. , Chiu Y. P. , Chang C. S. , Chen Y. W. , Tsong Tien T.
Published: February 2005

Two-dimensional periodic arrays of Pb nanopucks have been grown on Pb quantum islands at around 100 K using electronic superstructures on the island surface as templates. These superstructures originate from interfacial electron scattering. They are seen on the surface of Pb quantum islands grown on incommensurate Pb thin films on a Si(111)-7 ×7 surface. The rhombic unit cell of these superstructures can be divided into two triangles. Pb adatoms prefer to adsorb on the triangle with the face-centered cubic stacking. In an appropriate temperature range, the surface deposited atoms can hop more freely within the unit cell than across the cell boundary. The superstructures can thus serve as templates for the confined nucleation of nanopucks of deposited atoms.
A Method for Assembling Nano-Electromechanical Devices on Microcantilevers Using Focused Ion Beam Technology
Authors: Nagase Masao , Namatsu Hideo
Published: February 2005

We propose a new method for assembling nano-electromechanical devices using focused ion beam (FIB) technology. After milling the area surrounding a device (30 µm×10 µm), a small chip containing nano-four-point probes with 60-nm-pitch Si electrodes was picked up by a microprobe and transferred to a scanning probe microscopy (SPM) microcantilever with four aluminum electrodes. Interconnections by tungsten (W) lines between the Si electrodes of the nanodevice and the Al electrodes of the cantilever were formed by FIB-induced gas deposition. The connection of FIB-W lines was confirmed by biased scanning electron microscopy (SEM). We successfully demonstrated a nano-four-point probe system on an SPM cantilever.
Microscopic Observation of Nanofibers and Helical Nanoribbons Composed of Tetraether Cyclobolaphile
Authors: Shibakami Motonari , Miyawaki Kazuhiro , Goto Rie , Shigeno Masatsugu
Published: February 2005

In this paper, we describe the microscopic observation, using transmission electron microscopy and scanning probe microscopy, of self-assembled lipid nanostructures composed of a cyclic amphiphilic compound containing four ether bonds as a hydrophilic-hydrophobic linker, referred to as “tetraether cyclobolaphile”. Cyclobolaphiles mimic naturally occurring cyclic lipids found in archaea that exhibits extreme resistance to harsh environments. The general structural features of such artificial lipids include (i) a cyclic framework, (ii) two diacetylene units, and (iii) two hydrophilic groups. Our previous work has indicated that tetraether cyclobolaphile self-assembles into microtubules and sheet like aggregates in water. Our principle results, which are reported herein, show the self-organization of the lipid into nanofibers and helical nanoribbons in a dry form, which is likely triggered by electron beam and UV irradiation, respectively. In essence, the examination by transmission electron microscopy at a higher magnification indicated that the planar self-assembled lipid aggregates contain fibrous nanostructures with a width of approximately 4 nm. The scanning probe microscopic observation of the irradiated aggregates revealed the presence of fibers that exhibit right-handed helicity with an apparent width and pitch of 25 nm and 130 nm, respectively.
Optical Cognitive Information Processing – A New Field
Authors: Ovshinsky Stanford R.
Published: February 2005

I will discuss unique electronic and structural mechanisms of Ovonic optical phase-change devices making possible orders of magnitude increase of density of memory and introducing multiple information functions in a single nanostructure spot.
Crystallographic Studies on High-Speed Phase-Change Materials Used for Rewritable Optical Recording Disks
Authors: Matsunaga Toshiyuki , Yamada Noboru
Published: February 2005

Optical recording disks, which exploit the reversible phase-change phenomenon between amorphous and crystal states of a material, are now in extensive use, particularly in videodisc recorders for home use. The most commonly used recording materials are GeTe-Sb2Te3 pseudobinary compounds and Sb-Te binary compounds with a small quantity of added In, Ag, and/or Ge. These compounds, which have superior capabilities for holding data at room temperature for extended periods and high rewrite speeds, all tend to have structures in which one lattice site is occupied by two or more elements at random, and the lattices are all cubic or pseudocubic at the high temperatures at which recording and erasure are performed. In addition, with rising temperature, the amplitude of atomic thermal vibration increases exponentially. It is believed that these two characteristics of these materials that are suitable for phase-change optical disks, i.e., an isotropic structure and intense thermal vibration at high temperatures, play very important roles in the virtually instantaneous transformation from the amorphous to the crystal phase. We describe here the relationship between the structural features and the high-speed phase-change mechanism.
Surface Plasmon Effects on the Far-Field Signals of AgOx-Type Super Resolution Near-Field Structure
Authors: Liu Wei-Chih , Ng Ming-Yaw , Tsai Din Ping
Published: February 2005

A super-resolution near-field structure (Super-RENS) of AgO
x
type could perform the task of high-density near-field optical recording in a more feasible way. To further explore the optical resolution and controllability of super-RENS disks, the near-field and far-field optical properties of the AgO
x
-type super-RENS embedded with random silver nanoparticles and nano cavities of different densities were studied using finite-difference time-domain simulations. The random nanostructures yielded super-resolution capability, but the surface plasmon effects generated by the random metallic nanoparticles significantly enhanced the far-field signals. A simplified Fourier optical theory was proposed to understand the relationship between the enhanced near field of random nanostructures and the super-resolution capability in the far field.
Readout Modeling of Super Resolution Disks
Authors: Kataja Kari , Olkkonen Juuso , Aikio Janne , Howe Dennis
Published: February 2005

We describe 3-dimensional numerical simulations (performed using a finite-difference-time-domain modeling tool) of the readout of very small marks recorded on the data surface of an optical storage medium that incorporates a super resolution (SR) structure comprised of two dielectric thin films which encapsulate a thin AgO
x
film. We study how different types of light scattering objects, which are dynamically formed in the SR structure during readout of the recorded data surface, affect the characteristics of the reflected optical power modulation.
Calculation of Surface Plasmon Effect on Optical Discs
Authors: Chiu Kuo Pin , Lin Wei Chih , Fu Yuan Hsing , Tsai Din Ping
Published: February 2005

We calculated the conditions of surface plasmon resonance for various optical discs to evaluate the role of periodic lands and grooves or recording mark trains as grating couplers. With the typical parameters of structure used in the discs, it is shown that surface plasmons have a weak influence on ordinary optical discs. These results differ from the situation with super-resolution near-field optical structures where surface plasmons or localized surface plasmons have a considerable influence on such discs.
Advanced Technologies for Read Channel on Blu-ray Disc
Authors: Tonami Junichiro , Nakamura Hideki , Ohki Takayuki , Tashiro Takushi , Nakano Eiji , Ueno Tomonori , Hayami Atsushi
Published: February 2005

We propose advanced technologies to enhance the system performances of the Blu-ray disc (BD) system. The technologies are based on the read channel that we reported previously. Our previous read-channel was designed for a modulation code with Tmin (minimum length between transition) of 3 and whose f
s (system clock frequency) was higher than 1.5×f
c (channel rate). To achieve technical subjects such as robustness against asymmetry and noise on the BD, our target changed to a read-channel designed for a modulation code with Tmin of 2 (17pp modulation code). Furthermore, to achieve practical subjects for a production, the system clock frequency of the new read-channel became half-rate ( f
s is higher than 0.75×f
c) for saving power consumption, and the performance of the digital phase locked loop (DPLL) was reinforced for random access.
Spherical Aberration Detection Scheme for Optical Pickup Units Using the Push-Pull Signal
Authors: Knittel Joachim , Richter Hartmut
Published: February 2005

We present a new method to generate a spherical aberration error (SAE) signal for an optical pickup unit. The SAE signal is derived from two push-pull signals that are generated by a special diffractive optical element. First experiments provided a proof of principle.
Development of Signal Interpolated Phase Timing Recovery System for High Density Magneto-Optical Disks
Authors: Kanaoka Toshikazu , Taguchi Masakazu , Uchida Akiyoshi , Itakura Akihiro , Matsuura Michio
Published: February 2005

We developed a new timing recovery system for magneto-optical disks (MO) with a higher recording density and higher transfer rate but it is difficult to achieve these without signal to noise ratio (SNR) degradation in the MO readout signal. Therefore, for signal processing, we have developed a turbo code technology, [rf1] which can obtain a high enough coding gain. However, as optimal phase to obtain the optimum performance of the turbo code must be detected, we developed a very precise phase timing recovery system that works under a degraded SNR in the MO readout signal. Moreover, as the turbo code is a kind of block code, which requires decoding by a turbo block unit, we also developed a system for detecting the start point for turbo decoding. We developed a new timing recovery system and, in this paper, we report architecture and performance evaluations of this system.
Modified Partial Response Maximum Likelihood Detection Using the Relative Probability of the 17PP Code for Optical Storage Systems
Authors: Lee Joohyun , Lee Jaejin
Published: February 2005

In this paper, we propose a modified calculation method of the branch metric in partial response maximum likelihood (PRML) detection for high-density optical storage systems. The scheme is related to the relative probability of the run-length limited code. Hence, we also present the relative probabilities of the 17PP coded sequences for 2nd-, 3rd- and 4th-orders of PR targets. The modified PRML detection using the relative probability of the 17PP coded sequence has better bit error rate (BER) performance than conventional PRML detection.
A New Error Correction Algorithm for High-Density Optical Storage Systems
Authors: Kim Youngki , Lee Jun , Lee Jaejin
Published: February 2005

We propose a new error correction technique for high-density optical storage systems using a syndromechecking long-burst error detection scheme. The advantages are (1) easy code rate adjustment and (2) simple code construction (less inner code encoding and decoding time).
Orthogonal Frequency Division Multiplex with Multi-Level Technology in Optical Storage Application
Authors: Ma Chang-Po , Kuo Ji-Wen
Published: February 2005

We applied orthogonal frequency division multiplex (OFDM) to the optical storage system. By equalizing the channel and correcting the sampling frequency error in the frequency domain, and by using different modulations according to the bit error rate performance of the different carriers, we were able to increase the recording data density to 2.6 times of that of digital versatile disc (DVD).
Bit-Wise Volumetric Optical Memory Utilizing Two-Photon Absorption in Aluminum Oxide Medium
Authors: Akselrod Mark S. , Orlov Sergei S. , Akselrod Gleb M.
Published: February 2005

Aluminum oxide single crystal medium for volumetric optical memory utilizing two-photon absorption is investigated. Static and dynamic testers used to demonstrate bit-wise recording and confocal fluorescent readout. Recording is performed with blue 405 nm laser diodes. Less than 1 nJ of energy per recorded bit was found to be sufficient for data writing. “Negative” readout mode using blue 440 nm laser diode and green 520 nm fluorescence is demonstrated. “Positive” readout mode of operation using red 635 nm excitation laser light and 750 nm fluorescence shows high SNR and prolonged nonvolatile readout. Preliminary data using a dynamic spin-stand tester are presented as well.
Advanced Lens Design for Bit-Wise Volumetric Optical Data Storage
Authors: Zhang Yan , Milster Tom D. , Kim Jai Soon , Park Sang-Ki
Published: February 2005

The storage capacity of a fluorescent bit-wise volumetric optical data storage system is limited by the inter-layer crosstalk and the maximum compensation range of spherical aberration induced by different layers inside the medium. Lens designs of far-field and near-field optical systems suitable for volumetric storage are presented. The maximum compensation range of each design is calculated. The storage densities of far-field and near-field confocal systems in terms of bits-in-2 are derived based on the maximum compensation ranges and appropriate data layer spacings that induce a -30 dB maximum level of inter-layer crosstalk. It is shown that an optimized near-field system is able to achieve 1.65 Tb-in-2 data density.
Holographic Memories Using 2-Dimensional Phase-Code Multiplexing Method
Authors: Ezura Megumi , Baba Shigeyuki , Kihara Nobuhiro
Published: February 2005

When implementing a phase-code multiplexing method in real holographic storage systems, there are several factors of cross-talk noise which degrade signal-to-noise ratio (SNR). To reduce such problems, we developed a new and practical phase-code multiplexing method using a 2-dimensional high-resolution phase-only spatial light modulator (P-SLM) which encodes a reference beam with orthogonal phase codes. Theoretically and experimentally, we found that removing a particular all 0 phase code which is always generated by Walsh-Hadamard matrices is quite effective in reducing the cross-talk noise. Moreover, we found that periodically tiled phase-code patterns reduce the cross-talk noise due to inhomogeneous illumination of the P-SLM in real systems. By combining these methods, we achieved bit error rates (BER) for multiplexed holograms on the order of 10-4–10-3 without error correction.
Phase-Change Media for Ultrahigh-Speed Digital Versatile Disc Recording
Authors: Pieterson Liesbeth van , Rijpers Jan C. N. , Hellmig Jochen
Published: February 2005

Rewritable discs based on Ge-Sn-Sb phase-change compositions that combine high crystallization rates with good archival life stability were designed. The crystallization rate can be varied from 2–16× digital versatile disc (DVD) speed by variation of phase-change composition. The rate increases with decreasing Ge concentration and is dependent on dopants. For high-speed discs based on these compositions, back growth is substantial, but can be diminished by designing an efficiently cooled stack. By doing so, phase-change optical recording at 10× DVD rewritable (+RW) with 9% multitrack jitter is demonstrated using a 2T-period-based write strategy.
Dual-Layer Rewritable Phase-Change Recording Media for HD DVD System
Authors: Nakai Tsukasa , Tsukamoto Takayuki , Ashida Sumio , Yusu Keiichiro , Yoshida Nobuhisa , Umezawa Kazuyo , Ohmachi Noritake , Morishita Naoki , Nakamura Naomasa , Ichihara Katsutaro
Published: February 2005

We have investigated the recording characteristics of the dual-layer phase-change recording media for a system that uses the blue-violet laser (wavelength of 405 nm), with the numerical aperture of 0.65 and light incidence on 0.6-mm-thick substrate having the land and groove format (HD DVD). In order to achieve higher storage density for its beam spot size, a number of technologies have been incorporated into the media, such as the bismuth-substituted pseudobinary GeSbTe alloy recording film and hafnium oxide-based interface layer material. The feasibility of the user capacity of 36 GB has been successfully demonstrated.
Recording Mechanism of High-Density Write-Once Disks Using Inorganic Recording Material
Authors: Hosoda Yasuo , Mitsumori Ayumi , Sato Megumi , Yamaguchi Masataka
Published: February 2005

We realized an inorganic write-once disk using a Bi-Ge nitride alloy recording layer for an optical recording system for the Blu-ray disc format. We developed a recording system, which is composed of two types of metal nitride as a recording material. One metal nitride is decomposed easily by the heat of the laser beam during recording. The other metal nitride is not decomposed at that temperature. The recording signal modulation depends mainly on the reflectivity change of the recording layer caused by the decomposition of nitride. The non-decomposing nitride controlled the reaction and prevented deformation of the layer. Thus we could obtain a well-formed minute mark. We confirmed the reliability of our hypothesis on the recording mechanism by using another material, which is composed of Sn-N and Ti-N. By this method, we confirmed that this recording mechanism can be widely applied to any inorganic recording material.
Dynamics of Ultrafast Crystallization in As-Deposited Ge2Sb2Te5 Films
Authors: Wang Qin F. , Shi Lu P. , Huang Su M. , Miao Xiang S. , Wong Kai P. , Chong Tow C.
Published: February 2005

Femtosecond laser-induced ultrafast crystallization in 80 nm as-deposited Ge2Sb2Te5 films has been investigated by time-resolved microscopy. With an average fluence of approximately 10 mJ/cm2, a transient nonequilibrium state of the excited material was formed within 2 ps. The results can be interpreted as an electronically induced nonthermal phase transition.
A New Hard Coat on Cover Layer for Cartridge-Free Blu-ray Disc
Authors: Han Mi Young , Kang Tae-Sik , Lee Seong-Keun , Jang Sung Hoon , Seo Hun , Lee Chang-Ho
Published: February 2005

A new UV-curable hard coat resin with an excellent antifouling property has been developed. A 3-µm-thick hard coat layer was stacked onto a 97-µm-thick cover layer by spin coating. The characteristics of the hard coat layer, such as pencil hardness, microscratch resistance, adhesion, water contact angle and jitter, have been investigated.
Electron Beam Recorder with Nanometer-Scale Accuracy for 100 Gbit/in2 Density Mastering
Authors: Kitahara Hiroaki , Ozawa Yasuyuki , Asai Masafumi , Nishida Tetsuya , Wada Yasumitsu
Published: February 2005

An electron beam recorder (EBR) was developed for mastering optical disks with a recording density of 100 Gbit/in2 using a multilevel recording format. In this recording format, a nanometer-scale accuracy of relative pit edge position is required in both radial and tangential directions. To achieve the recording position accuracy, a rotation stage with a noncontact vacuum seal and a correction system for rotation errors were developed. In addition, an active magnetic shield system and a learning compensation for beam displacement were adopted to improve the stability of the beam position. As a result, the ability to record with high accuracy and high resolution was confirmed from experimental results. A fine pit pattern with a minimum pit length of 70 nm was formed precisely. The recording accuracy of the EBR was evaluated to be approximately 2 nm (standard deviation) in both radial and tangential directions. Furthermore, a carrier-to-noise ratio of 64 dB was also obtained by reproducing an etched silicon master with a 240 nm monotone pit pattern.
Traveling-Wave Photodetector with Asymmetrically Heterostructured Intrinsic Region
Authors: Choe Joong-Seon , Kwon Yong-Hwan , Kim Kisoo , Kim Jeha , Kong Soon-Cheol , Choi Young-Wan
Published: February 2005

Bandwidth limitation by carrier transit time was analyzed mathematically when traveling-wave photodetector's intrinsic region consists of heterostructure. Because of the smaller hole's velocity than electron's, the hole transit length is crucial for determining the large bandwidth. In order to compensate the small transit velocity of hole, we propose that the intrinsic region should be designed asymmetrically. In this study we found that appropriate asymmetric structure enhanced bandwidth by about 100% of symmetric structure and proved experimentally the effect of asymmetric intrinsic region.
Metalorganic Vapor Phase Epitaxy Growth of InAlAsSb on InP
Authors: Yokoyama Haruki , Sugiyama Hiroki , Oda Yasuhiro , Sato Michio , Watanabe Noriyuki , Kobayashi Takashi
Published: February 2005

This paper studies the characteristic of InAlAsSb grown on InP substrates by metalorganic vapor phase epitaxy (MOVPE) using trimethylindium (TMI), trimethylaluminum (TMA), trimethylantimony (TMSb) and arsine (AsH3). Composition analyses of InAlAsSb layers grown at various TMSb flow rates show, for the first time, that the Al concentration in the InAlAsSb layer decreases as the TMSb flow rate increases. We also find that the growth rate of InAlAsSb decreases remarkably as the TMSb flow rate increases. To clarify the reasons for these phenomena, the growth rates of the InAsSb and AlAsSb components are estimated. The growth rate of AlAsSb component shows a similar remarkable tendency with the InAlAsSb growth rate but that of InAsSb almost retains. This means that the decomposition of TMA is suppressed by the presence of TMSb. It is shown that excess Sb on the growth surface is related to this suppression.
Influence of Excimer Laser Beam Shape on Poly-Si Crystallisation
Authors: Brotherton S. D. , McCulloch D. J. , Gowers J. P.
Published: February 2005

Excimer laser crystallization is the currently preferred technique for the fabrication of high performance poly-Si thin film transistors for use in active matrix displays with integrated drive circuits. One of the issues with this process is the trade-off between increased throughput, by reducing the number of laser shots per unit area, and the range of laser energies over which this can be reliably implemented. The fundamental aspects of the crystallization process are analysed, and it is demonstrated that the size of the laser process window has a complex dependence on beam shape and shot number. Experimental results are presented, which show good consistency with a simple analytical model, and the optimum beam shape, and the limits to its application, are discussed.
New Analytical Modeling for Photoinduced Discharge Characteristics of Photoreceptors
Authors: Teshima Akitomo , Miyazaki Seiichi
Published: February 2005

We have developed a new analytical model to simulate the photoinduced discharging characteristics of photoreceptors under illumination, where the electrical potential on the positively precharged surface is decayed by not only the charge neutralization with photogenerated electrons but also the drift of photogenerated holes in the photoconductive layer accompanied with trapping at localized defect states. The hole trapping involves a temporal change in space charge. As an example, we have demonstrated that for amorphous Silicon (a-Si:H)-based photoreceptors fabricated by the plasma-enhanced chemical vapor deposition (PECVD), the photoinduced discharge characteristics measured under weak light illumination are well reproduced with the newly developed analytical model where the quantum efficiency for photoexcitation, hole trapping rate and hole mobility in the photoconductive layer are parameters to determine the internal electric field and potential. From the influence of these parameters on photoinduced discharge characteristics, we have also shown the usefulness of this model in analyzing photoreceptor performance.
Modeling of Nonvolatile Memory Operation of Polysilicon–Oxide–Nitride–Oxide–Semiconductor and Analysis of Program Characteristics Dependent on the Trap Distribution in the Silicon–Nitride Layer
Authors: Imanaga Syunji , Aozasa Hiroshi
Published: February 2005

We performed modeling and simulations of polysilicon–oxide–nitride–oxide–semiconductor (SONOS) memory devices with traps for charge accumulation. Comparisons of the dependence of writing and erasing characteristics on the tunnel-SiO2-layer thickness and SiN
x
-layer thickness were made. Simulated results of erasing characteristics are in good agreement with the experimental results, but simulated results of writing characteristics are not. Moreover, we simulated the dependence of writing and erasing characteristics on the distribution of the trap density in the SiN
x
layer, the dependence of writing characteristics on the doping density of polysilicon for the gate, and the dependence of the injection current and leakage current on the gate pulse duration.
Applications of a Novel Microheater in Micromolding
Authors: Cheng Chao-Min , Ho Mon-Shu
Published: February 2005

A modified local heating procedure is presented that reduces the sheet resistance of silicon wafers used as heating regions. The temperature-dropping gradient is improved obviously with our novel microheater during micromolding. In comparison with the nonsteady diffusion model, secondary ion mass spectrometry (SIMS) measurements show better agreement of nonsteady diffusion model at high temperature than at low temperature. Fine polymer microstructures can be obtained effectively by our micromolding process using a novel microheater.
Characterization of Nonlinear Optical Properties of Silver Oxide Super Resolution Near-Field Structures by Z-Scan Measurements
Authors: Chou Yu-Lin , Chuang Cheng-Ta , Chang Yu-Ming , Tsai Din-Ping
Published: February 2005

Femtosecond laser Z-Scan measurements are used to characterize the nonlinear optical properties of AgO
x
super resolution near-field structures (super-RENS). Open aperture Z-Scan measurements reveal a complex transient nonlinear optical absorption response of AgO
x
super-RENS under intensive laser irradiation. This is attributed to the thermal decomposition of AgO
x
into Ag nanoparticles in the near-field optical mask layer. A bi-compositional model is proposed to explain this complex nonlinear optical response. The threshold laser peak intensity for the phase transition and the nonlinear optical absorption coefficient of an Ag nanoparticle are determined to be I
th∼0.3 GW/cm2 and β=(-5.6±0.5)×103 cm/GW at λ=800 nm, respectively.