bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Annealing on Molecular Orientation of Rubbed Polyimide Film Observed by Reflection Ellipsometry
Authors: Ichiro Hirosawa Ichiro Hirosawa , Nobuyoshi Sasaki Nobuyoshi Sasaki
Published: October 2002

The influence of annealing on the molecular orientation of rubbed polyimide film was investigated using reflection ellipsometry. A marked decrease in the in-plane anisotropy of polyimide film was observed when annealing above 130° C. Detailed analysis proved that the decrease in anisotropy was due to the change in the molecular orientation direction in the temperature range of 130–230° C. Annealing at 280° C not only changed the direction of orientation but also the disordering of polyimide orientation.
Range-resolved Image Detection of Laser-induced Fluorescence of Natural Trees for Vegetation Distribution Monitoring
Authors: Saito Yasunori , Hatake Ken-ichiro , Nomura Eiji , Kawahara Takuya D. , Nomura Akio , Sugimoto Nobuo , Itabe Toshikazu
Published: October 2002

Fluorescence images of in vivo and natural tree leaves induced by the second harmonic of a Q-switched YAG laser have been remotely and directly detected by a lidar with a gated image-intensified charge-coupled-device (II CCD) camera. Simple spectroscopic measurements using a colored glass filter showed that the fluorescence was caused by the chlorophyll in the leaves. The chlorophyll fluorescence was useful to distinguish trees and other objects. Tree locations up to a distance of around 150 m from the system were also determined with a range resolution of 15 m from the range-resolved fluorescence images. The results showed that this technique has a great potential use as a monitor of vegetation distribution.
Halo Formation from Mismatched Axisymmetric Beams in a Periodic Focusing Channel
Authors: Masanori Ikegami Masanori Ikegami , Hiromi Okamoto Hiromi Okamoto
Published: October 2002

In a recent paper [H. Okamoto and M. Ikegami: Phys. Rev. E 55 (1997) 4694], we investigated halo formation from mismatched axisymmetric beams in a uniform focusing channel, developing a 1D space-charge code dedicated to breathing-mode study. We proceed now to a periodic focusing situation, generalizing the work. Several realistic beam distributions are used to self-consistently explore the halo properties of breathing beams. It is found that the fundamental quantities, such as maximum halo extent, halo intensity, etc., exhibit the features analogous to those obtained in the previous study unless the resonant instability driven by the periodicity of the external restoring force takes place. A large stop band of the second-order structure-driven resonance is encountered in the region σ0>90° while higher-order resonances are usually much weaker. We further demonstrate that a halo may be removed by means of a multiple collimator system provided that the wake fields generated by the collimators are negligible.
Improved Properties of Silicon Nitride Films Prepared by the Catalytic Chemical Vapor Deposition Method
Authors: Shinya Okada Shinya Okada , Hideki Matsumura Hideki Matsumura
Published: October 2002

The properties of silicon nitride (SiNx) films produced by the catalytic chemical vapor deposition (cat-CVD) method are extensively studied for device application. In the cat-CVD method, the deposition gases such as a silane (SiH4)) and ammonia (NH3)) gas mixture are decomposed by catalytic cracking reactions with a heated catalyzer near the substrates, and the SiNx films are formed at substrate temperatures around 300°C without using plasma. It was found that the electrical insulating properties such as resistivity and breakdown voltage and also the optical properties of the cat-CVD SiNx films were almost similar to those of high-temperature thermal CVD films, and that the hydrogen content was much lower than that of conventional plasma enhanced CVD (PE-CVD) films and was only a few atomic percent. It was also revealed that the film was water-resistive, the chemical etching rate was just 1/10 of that for PE-CVD films, and that the step coverage of cat-CVD SiNx films was conformal. The films are expected to be used as new device passivation films and are superior to the conventional PE-CVD SiNx films.
Spectral Properties of Cavity Radiation: Nonuniversal Characteristics
Authors: Sasanuma Michio , Onoue Takashi , Hayashino Katsuhiro Nakamura
Published: October 2002

The spectral properties of thermal radiation from a stadium-type cavity are examined. The significant effects of the shape and material species of the cavity wall on the spectral intensity are observed. The fluctuation of radiation intensity amounts to ten percent of the standard intensity estimated by use of Planck's formula and reveals the non-equilibrium and non-universal nature of the cavity radiation.
Schematic Model for the Migration of Interstitialcy-Type Self-Interstitial Including the Middle State
Authors: Yoshida Masayuki , Tsuruno Reiji , Kamiura Yoichi , Takahashi Manabu , Tomokage Hajime
Published: October 2002

Migration of interstitialcy-type self-interstitial is considered to be the repetition of breaking a bond and forming a new bond. Based on this, if a split-<100> self-interstitial is most stable, it migrates via a bond-centered self-interstitial. If a bond-centered self-interstitial is most stable, it migrates via a split-<100> self-interstitial.
Stability of UV-Type Two-Domain Wide-Viewing-Angle Liquid Crystal Display
Authors: J. Chen Yukito Saitoh , Alan Lien Alan Lien
Published: October 2002

We calculated the Gibbs free energy for the splayed-twist state, the reversed-twist state, and the reversed-tilt state of UV-type two-domain wide-viewing-angle thin film transistor liquid crystal display (TFT-LCD) panels to evaluate the stability of the three configurations. We show that the smaller tilt angle is the dominant fact on that influences the stability of the splayed-twisted state. Further more, at high applied voltage, the reversed-tilt state is the most unstable, and is easily deformed into the reversed-twist state. Methods are therefore proposed for reducing the reversed-tilt state area. General trends of the critical voltage as a function of the chiral pitch, twist angle, cell gap, dielectric constant, and elastic constant are also discussed.
Surface Optical Second Harmonic Generation from Rutile TiO2(110) in Air
Authors: Kobayashi Eiichi , Mizutani Goro , Ushioda Sukekatsu
Published: October 2002

We have measured the azimuthal angle dependence of the SH intensity from the (110) face of TiO2 (rutile) in air at the fundamental photon energy of 2.33 eV. The pattern of the SH intensity shows two-fold symmetry for the p -in/ p -out polarization configuration, four-fold symmetry for the p -in/ s -out polarization configuration, and two-fold symmetry for the s -in/ p -out polarization configuration. From the results of the experimental and theoretical analyses we have concluded that the observed SH light is generated from the surface electric dipole polarization.
Nanometer-Scale Lithography on the Oligosilane Langmuir-Blodgett Film
Authors: Maruyama Hiroyuki , Kosai Nobuyuki , Sato Tadatake , Sagisaka Shigehito , Segawa Hiroshi , Takeo Shimidzu Takeo Shimidzu , Kazuyoshi Tanaka Kazuyoshi Tanaka
Published: October 2002

Nanometer-scale lithography was performed by applying the local electric field of scanning tunneling microscope (STM) to an oligosilane Langmuir-Blodgett (LB) film composed of tridecamethylhexasilanylacetic acid ( MeSi6AA) transferred onto a facet of a gold single crystal. After halting the probe tip and applying a higher bias voltage than is usual for STM imaging with feedback on, holes with diameters of 30–50 nm appeared. The formation of the holes depended on the polarity and bias applied. These results are accounted for because the electron beam emitted from the tip under high electric field broke the LB film. It was also discovered that fixation of the tip by making the feedback off could create holes with diameters of less than 10 nm.
Growth of Crystalline Silicon on a Cryogenic Substrate by Photochemical Reaction in a Condensed Phase
Authors: Kataoka Toshihiko , Endo Katsuyoshi , Ashida Masayoshi , Orita Hiroyuki , Oshikane Yasushi , Haruyuki Inoue Haruyuki Inoue , Yuzo Mori Yuzo Mori
Published: October 2002

We have studied photochemical deposition in a condensed phase. In the experiment, liquid silane ( SiH4) on a cryogenic substrate is irradiated with KrF and ArF excimer laser. The deposited film is characterized by Raman scattering, scanning electron microscopy, transmission electron microscopy and transmission electron diffraction. The film is composed of many rod-like crystalline silicon (c-Si) products. Their diameter and height are 400–500 nm and 500–700 nm, respectively. It is remarkable that the rod-like c-Si has grown on the cryogenic substrate. Therefore, we consider that the liquid-solid interface reaction plays an important role in the crystallization growth. In other words, the growth from the c-Si surface is necessary for crystallization. This technique solves general problems in photochemical vapor deposition techniques, such as deposition on the optical window, thermal damages of the substrate and the low deposition rate in the gas phase.
X-Ray Stress Measurement of Mounted Silicon Chips
Authors: Fujii Nobuyuki , Inui Katsunori , Kozaki Shigeru
Published: October 2002

Stresses in semiconductor silicon chips were measured by an X-ray stress measurement method that is applicable to microareas (60 µ m dia.) of single crystals. The measurement was conducted before and after silicon chip mounting on a substrate. Also measured were residual stresses in areas around bumps. As a result, about +30 to +40 MPa tensile stresses were determined at the corners of the rear side of a test piece silicon chip, which was fixed with resin, and about +70 to +80 MPa tensile stresses were found near the solder-bump formed surface of another test piece silicon chip.
Estimate of Light Scattering Loss of Amorphous Polymer Glass from Its Molecular Structure
Authors: Tanio Norihisa , Koike Yasuhiro
Published: October 2002

The fluctuation theory indicates that the isotropic light scattering loss of amorphous polymer glass, which is used as a material for polymer optical fiber, decreases with the decrease in isothermal compressibility β and refractive index. In order to prepare low light-scattering-loss polymer glass, it is necessary to know the isothermal compressibility of polymers. However, the β for most polymers has not yet been measured precisely using a mechanical procedure. In this work, we estimate the isothermal compressibility of amorphous polymer glass from its molecular structure and calculate its isotropic light scattering loss.
Proximity Effect Correction For Electron Beam Lithography: Highly Accurate Correction Method
Authors: Takashi Kamikubo Takashi Kamikubo , Takayuki Abe Takayuki Abe , Susumu Oogi Susumu Oogi , Hiroto Anze Hiroto Anze , Mitsuko Shimizu Mitsuko Shimizu , Masamitsu Itoh Masamitsu Itoh , Tetsuro Nakasugi Tetsuro Nakasugi , Tadahiro Takigawa Tadahiro Takigawa , Tomohiro Iijima Tomohiro Iijima , Yoshiaki Hattori Yoshiaki Hattori , Toru Tojo Toru Tojo
Published: October 2002

A new formula for proximity effect correction is discussed. The formula is represented by a series expansion. When infinite terms are used, the formula gives accurate optimum correction doses. The correction accuracy of the new formula is evaluated for the worst case scenario and compared with the conventional formula. It is shown that (1) the new formula suppresses correction errors to less than 0.5% for the deposited energy and (2) dimensional errors are less than 4 nm, even if only the first 3 terms are calculated for critical patterns. By using the new formula, the proximity effect correction can be carried out with sufficient accuracy, even for making reticles of 1 Gbit or higher-capacity DRAMs.
The Effect of Down-Flow Cleaning Process on Materials Used in an Electron Beam System
Authors: Naoharu Shimomura Naoharu Shimomura , Munehiro Ogasawara Munehiro Ogasawara , Kenji Ohtoshi Kenji Ohtoshi , Satoshi Yamasaki Satoshi Yamasaki , Yuji Fukudome Yuji Fukudome , Ryoichi Hirano Ryoichi Hirano , Shuichi Tamamushi Shuichi Tamamushi , Toru Tojo Toru Tojo , Tadahiro Takigawa Tadahiro Takigawa
Published: October 2002

In order to search for an appropriate material for an electron beam (EB) system to which in situ cleaning is applied, we investigated the particle generation due to the cleaning process and beam drift due to charging of the processed electrodes. In order to study the particle generation, we observed the change of surface morphologies of materials caused by the cleaning process. Particles are generated on the surfaces of Ag and BeCu. Particle generation is not observed on the surfaces of Ti, Cu, BeCu (Au-plated), Au, Al, Al (Au-plated), Al (Ni plated) and Pt. In order to study the charging effect, we measured the beam drift after cleaning the electrodes. The beam drift is small when Au and Ti electrodes are used and large when Ni plated electrodes are used. Therefore, Au and Ti are suitable materials for the EB system to which the in situ cleaning process is applied.
Internal Stress and Microstructure of WNx Bilayer Films for X-Ray Masks
Authors: Lee Don-Hee , Park Chil-Keun , Song Ki-Chang , Jeon Young-Sam , Lee Tae Ho , Jeong Chang Young , Ahn Jinho
Published: October 2002

In order to obtain the low-stress absorber for the X-ray mask, we have investigated the internal stress and the microstructures of WN

x

bilayer films with the structure of amorphous/crystalline phases. WN

x

film goes through a transition from an amorphous phase to a crystalline phase as the N2 content in the working gas increases. WN

x

bilayer film was prepared by two-step sputtering with varying N2 content of 10% for the crystalline phase and 5% for the amorphous phase. Precise stress control of the film was carried out by step annealing in a N2 atmosphere. We could obtain the internal film stress of less than 10 MPa by step annealing. The WN

x

bilayer film exhibits a very smooth surface with roughness of less than 1 nm and a long term stress stability less than of 2 MPa in air.
Fabrication of Aspherical Mirrors for Extreme Ultra-Violet Lithography (EUVL) Using Deposition Techniques
Authors: Masahito Niibe Masahito Niibe , Takeo Watanabe Takeo Watanabe , Hiroo Kinoshita Hiroo Kinoshita
Published: October 2002

Mirrors for the imaging optics of extreme ultra-violet lithography (EUVL) systems require highly precise figure processing. We have examined a method of fabricating the aspherical surfaces by deposition. A film of graded thickness is deposited on a spherical substrate using an RF-plasma-enhanced magnetron sputtering system with a deposition mask. The distribution in thickness of the deposited film is close to the designed value, and the method was shown to be feasible for figuring aspherical surfaces. The deposition films for the method are required to have little surface roughness and low residual stress. We have compared the roughnesses and residual stresses in Mo single layer films and Mo/Si multilayer films used in mirrors for soft X-rays. Both values for Mo/Si multilayers were about one order of magnitude smaller than those for Mo single layer films. The roughness of Mo/Si multilayer films almost satisfies the required value for EUVL optics; however, further study is necessary to diminish the residual stress.
Electron Beam Assisted Chemical Etching of Single-Crystal Diamond Substrates with Hydrogen Gas
Authors: Jun Taniguchi Jun Taniguchi , Iwao Miyamoto Iwao Miyamoto , Naoto Ohno Naoto Ohno , Ken'ichi Kantani Ken'ichi Kantani , Masanori Komuro Masanori Komuro , Hiroshi Hiroshima Hiroshi Hiroshima
Published: October 2002

The electron beam assisted chemical etching (EBACE) method with hydrogen gas is applicable to direct fine patterning of single-crystal diamond substrates. A scanning electron microscope (SEM) combined with a gas introduction system was used for EBACE. Hole, line and rectangular patterns were successfully fabricated. In the case of fabrication of the rectangular pattern, the etched depths are proportional to the electron dose. The etching rate using oxygen gas is faster than that using hydrogen gas. Raman scattering was used to confirm whether amorphous carbon was formed on the etched areas. The obtained Raman spectra indicate that areas etched using both hydrogen gas and oxygen gas do not form amorphous carbon.
Reactive Ion Etching of Diamond in O2 and CF4 Plasma, and Fabrication of Porous Diamond for Field Emitter Cathodes
Authors: Hiromu Shiomi Hiromu Shiomi
Published: October 2002

Reactive ion etching (RIE) of synthetic Ib diamond and chemical vapor deposition (CVD) diamond films in O2 and CF4 has been investigated. The large etch rate of up to 2.8 µ m/h and etch rate ratios of 15–20 for diamond (100)/Al were obtained at CF4/O2=10–20%. Numerous columnar structures of approximately 300 nm length and 10 nm width have been made by etching CVD polycrystalline diamond films in O2 plasma. The structures made the diamond film “porous”. A comparative study of field emission characteristics has been made for as-grown diamond films and porous diamond films. The average turn-on field was in the range of 2–3 V/µ m for porous diamond films and 6–8 V/µ m for as-grown diamond films.
Epitaxial Growth of Poly(dimethylsilane) Evaporated Films on Poly(tetrafluoroethylene) Layer
Authors: Reiji Hattori Reiji Hattori , Yukio Aoki Yukio Aoki , Takeshi Sugano Takeshi Sugano , Junji Shirafuji Junji Shirafuji , Tsuyoshi Fujiki Tsuyoshi Fujiki
Published: October 2002

Epitaxially grown poly(dimethylsilane) (PDMS) films have been prepared by evaporation on a highly-oriented poly(tetrafluoroethylene) (PTFE) layer which is formed by means of a mechanical deposition technique. The orientation characteristics of PDMS films are determined using atomic force microscopy, polarizing microscope images, X-ray diffraction patterns and polarized absorption spectra. The oriented regions lie along the grooves (1–5 µm wide) formed on the PTFE layer. The X-ray diffraction patterns and the polarized absorption spectra indicate that the (110) plane of the crystal structure is parallel to the substrate surface and that the c-axis of the Si-backbone chain is parallel to the grooves on the PTFE-coated substrate.
Spatially Averaged (Global) Model of Time Modulated High Density Chlorine Plasmas
Authors: Ashida Sumio , Lieberman Michael A.
Published: October 2002

Properties of chlorine plasmas generated in a high-density, low pressure ( ∼5 mTorr) plasma source using a pulsed-power modulation method are calculated by a spatially averaged (global) model. Both time resolved and time average plasma properties are discussed. The recombination coefficient for chlorine atoms at the wall plays an important role in determining the electronegativity of the plasma, since the dissociation fraction of the gas greatly affects the generation of negative ions. Even for such discharges, which have substantial electronegativity in the bulk plasma, it is only possible to extract negative ions at the walls by using modulations having longer “off” times than a few tens of microseconds. This is the time scale required for the sheath voltage, which confines negative ions within the bulk plasma, to collapse, due to thermalization and loss of electrons.
Evaluation of Ozone Condensation System by Thermal Decomposition Method
Authors: Migita Shinji , Sakai Kazuo , Mori Zon , Hiroyuki Ota Hiroyuki Ota , Ryozo Aoki Ryozo Aoki
Published: October 2002

An ozone condensation system is evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone is condensed by the adsorption method and its concentration is analyzed using the thermal decomposition method. The concentration of ozone exceeds 90 mol% and ozone is supplied for a sufficiently long time to grow oxide thin films. Investigation of the ozone decomposition rate demonstrates that ozone can be transferred into the film growth chamber without marked decomposition. The ozone concentration is also evaluated using a quadrupole mass analyzer and the accuracy of this method is compared with the results of the thermal decomposition method.
Fluorine-Related Defects in BF2
+-Implanted Si Probed by Monoenergetic Positron Beams
Authors: Uedono Akira , Kitano Tomohisa , Watanabe Masahito , Moriya Tsuyoshi , Komuro Naoyuki , Kawano Takao , Tanigawa Shoichiro , Suzuki Ryoichi , Ohdaira Toshiyuki , Mikado Tomohisa
Published: October 2002

Fluorine-related defects in 30-keV BF2
+-implanted Si were probed using monoenergetic positron beams. From measurements of Doppler broadening profiles of the annihilation radiation as a function of incident positron energy and those of lifetime spectra of positrons, depth profiles of defects and the species of the defects were determined. For an as-implanted specimen, the major species of the defects below the amorphous region was identified to be divacancies. Upon rapid thermal annealing above 700 °C, solid phase epitaxial growth of the amorphous region started, but no shift of the depth profile of defects detected by the positron annihilation technique was observed. During the regrowth of the amorphous region, vacancy-fluorine complexes were introduced. The complexes between vacancy clusters and fluorine atoms were observed even after 1100 °C annealing.
Raman Scattering and Two-Phonon Infrared Transmission Spectra of Cu(AlxGa 1-x)S 2 Crystals
Authors: Terasako Tomoaki , Nozomu Tsuboi Nozomu Tsuboi , Hisao Uchiki Hisao Uchiki , Seishi Iida Seishi Iida
Published: October 2002

First- and second-order Raman scattering and two-phonon infrared (IR) transmission measurement results for Cu(Al

x

Ga1-
x

)S2 single crystals have been examined as a function of x. It is apparent that the highest frequency B2 and E modes at the zone center exhibit two-mode(persistence)-type behavior. The appearance of the two-mode-type behavior in a ternary alloy system is shown to be explainable by theoretical consideration based on a modified model of the type judging criterion. In addition, some of the two-phonon IR absorption bands and second-order Raman peaks are found to be due to phonons located at zone-boundary points. Compositional dependence of the A1(W1) mode Raman line shape and the appearance of a cross-coupled phonon between the two modes indicate that the clustering effect is essentially suppressed in this alloy system.
Real-Time Enhancement of Defects in Periodic Patterns Using Photoinduced Anisotropy of a Bacteriorhodopsin Film
Authors: Takayuki Okamoto Takayuki Okamoto , Kenji Yamagata Kenji Yamagata , Ichirou Yamaguchi Ichirou Yamaguchi
Published: October 2002

We propose a defect-enhancement system for periodic patterns using a nonlinear spatial filter that uses photoinduced anisotropy of a bacteriorhodopsin film. The nonlinear filter passes low-intensity beams while blocking high-intensity beams. The system enhances the defects in real time because the anisotropy induced on the bacteriorhodopsin film by the first sample does not have to be rewritten if subsequent samples have the same periodic structure. It can also be applied to moving samples due to the shift invariance of the Fourier pattern. In the experiments we detected 10 µm defects in a photomask for a liquid crystal display. The dependence of the contrast ratio of the enhanced defect to the background on the intensity of the probe beam is also measured.
Transport Properties in InP/InAlAs Type II Single Heterostructure
Authors: Inoue Hiroshi Matsui , Hidetoshi Iwamura Hidetoshi Iwamura , Satoshi Endo Satoshi Endo , Hiroshi Uozaki Hiroshi Uozaki , Naoki Toyota Naoki Toyota
Published: October 2002

A type II interface is formed in an undoped InP/InAlAs single heterostructure grown by gas source molecular beam epitaxy. From measurements of the electrical resistivity, magnetoresistance and Hall effect, it is confirmed that a two-dimensional electron gas system containing a sheet carrier concentration of 1.8 × 1011 cm-2 is formed in the single hetero interface. In this study, the effective mass is estimated to be 0.074m
0, corresponding to the 1st subband by the Shubnikov-de Haas effect at different temperatures. It can be clarified experimentally that the effective mass of the 1st subband is almost equal to the electron-mass in bulk InP. The energy difference between the Fermi level and the 1st subband is obtained as 5.8 meV, which is lower than the energy separation between the 1st and 2nd subbands.
Exchange Kinetics of Alkanethiol Self-Assembled Monolayers Probed by Attenuated Total Reflection with Enhancement of Surface Plasmon Resonance
Authors: Kajikawa Kotaro , Hara Masahiko , Hiroyuki Sasabe Hiroyuki Sasabe , Wolfgang Knoll Wolfgang Knoll
Published: October 2002

Exchange kinetics for octanethiol ( C8H17SH) self-assembled monolayers (SAMs) by octadecanethiol ( C18H37SH) in solution are studied by in situ measurements of reflectivity in the attenuated total reflection (ATR) geometry with surface plasmon resonance (SPR) enhancement. While rapid exchange kinetics are found for the octanethiol SAM prepared by 1-day exposure to the ethanol solution, the octanethiol SAM prepared by 30-minute exposure exhibits only slow exchange kinetics. This fact may originate from different adsorption states, due to the gradual dimerization of the octanethiol monomers during their exposure to the solution, with dimers being less strongly adsorbed than the monomers.
Nb/Nb Oxide-Based Planar-Type Metal/Insulator/Metal (MIM) Diodes Fabricated by Atomic Force Microscope (AFM) Nano-Oxidation Process
Authors: Shirakashi Jun-ichi , Matsumoto Kazuhiko , Miura Naruhisa , Konagai Makoto
Published: October 2002

A novel fabrication technique for fabricating metal/oxide-based electron devices was investigated using an atomic force microscope (AFM) nano-oxidation process. This technique was applied to the surface modification of niobium (Nb) thin films. Successful surface oxidation of Nb was performed by applying a negative bias voltage to a conductive cantilever. Ultra-narrow Nb oxide wires could be obtained by precisely adjusting oxidation parameters such as scanning speeds and applied bias voltages. Using this technique, planar-type metal/insulator/metal (MIM) diodes with a Nb/Nb oxide system were fabricated. Nb-based MIM diodes clearly showed nonlinear current-voltage ( I-V ) characteristics. Furthermore, the electrical properties of Nb/Nb oxide junctions were studied in detail using MIM diode structures. From the temperature dependence of I-V characteristics on the MIM diodes, a barrier height of 133 meV and a relative dielectric constant of 64 were obtained in the single-junction Nb/Nb oxide system.
Measurement of the Delamination of Thin Silicon and Silicon Carbide Layers by the Multi-Wavelength Laser Ellipsometer
Authors: Hara Tohru , Kakizaki Yasuo , Tanaka Hisao , Inoue Morio , Kajiyama Kenji , Yoneda Tomoaki , Masao Katsuya
Published: October 2002

The refractive index and thickness of a triple layer are measured using a multi-wavelength laser ellipsometer, where three different wavelengths around 750 nm were employed. This measurement gives the refractive indexes and thicknesses of the delaminated Si layer and the air gap. The thickness of the delaminated Si layer and air gap are 774 nm and 60 nm, respectively, in the H+ implanted Si layer with annealing at 600° C. The delamination of the 619-nm-thick SiC layer can also be observed by this measurement in 6H SiC, where H+ is implanted at 100 keV with 1×1017 ions/cm2 and annealing is performed at 800° C for 10 min. This nondestructive ellipsometric measurement is useful for the delamination study of Si and SiC layers.
Precision Side-Polished Fibers with a Long Interaction Length
Authors: Liaw Shien-Kuei , Chiu Jin-Yu , Tseng Shiao-Min
Published: October 2002

We succeeded in fabricating precision side-polished fibers embedded in silicon V-grooves and then polished six fibers using a home-made polisher. The control of the polishing depth of the side-polished fibers was as accurate as ±0.25 µ m. Another merit of our polished samples was their negligible losses even though the effective interaction lengths were long. Experimental calibrations of our samples agreed with theoretical results.
Thermal Stability of Magnetically-Aligned Nematic Liquid Crystal Layer on Nonrubbed Polyimide Surface
Authors: Akiyama Hidenari , Yoshida Norihiro , Nishikawa Michinori , Kobayashi Shunsuke , Yasufumi Iimura Yasufumi Iimura
Published: October 2002

We have studied the thermal stability of liquid crystal (LC) molecules adsorbed on two different polyimide films. LC molecules adsorbed on the polyimide film with a high polarity show higher thermal stability than those adsorbed on the polyimide film with a low polarity. This result is strongly related to the nematic wetting property of the polyimide films; the polyimide film that shows high wettability of the nematic phase gives high thermal stability of LC molecules adsorbed on the film. The result is also analyzed using a two-dimensional rotation diffusion model, and the importance of the nematic wetting property for the thermal stability is emphasized in relation to the surface LC ordering.
Dynamic Properties of InAs Self-Assembled Quantum Dots Evaluated by Capacitance-Voltage Measurements
Authors: Horiguchi Naoto , Futatsugi Toshiro , Yoshiaki Nakata Yoshiaki Nakata , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

We report on the dynamic properties of electron transport between InAs self-assembled quantum dots and n-GaAs substrate through tunneling barrier. The time constant of the electron transport was estimated by making use of the frequency dependence of the capacitance increase due to the InAs dots. The time constant ranged from microseconds to submicroseconds in samples with 40 nm tunneling barriers. The value was consistent with the theoretically calculated CR time constant.
Magnetic Quantum Oscillations in In 0.53Ga 0.47As/In 0.52Al 0.48As Multiquantum Well Observed by Millimeter Wave Response
Authors: Hiroshi Matsui Hiroshi Matsui , Masaki Narushima Masaki Narushima , Yuichi Kawamura Yuichi Kawamura , Naohisa Inoue Naohisa Inoue , Satoshi Endo Satoshi Endo , Hiroshi Uozaki Hiroshi Uozaki , Naoki Toyota Naoki Toyota
Published: October 2002

We report on millimeter wave measurements of an In0.53Ga0.47As/In0.52Al0.48As multiquantum well fabricated by gas source molecular beam epitaxy. Transmission experiments with the millimeter waves (16–110 GHz) were carried out as a function of the magnetic field up to 10 T at temperatures down to 0.6 K. The quantum oscillations corresponding to the Shubnikov-de Haas effect are observed in the amplitude and phase of the transmitting waves. The effective mass can be estimated as 0.058m
0 for the 1st-subband electron. In spite of a small Fermi energy of 27 meV for the 1st subband, the enhancement of an effective mass is 30% over the bulk band-edge mass of 0.041m
0. The large difference originates from the resonant polaron coupling due to a fundamental GaAs-like LO-phonon in addition to the band nonparabolicity of the In0.53Ga0.47As well.
Femtosecond Refractive-Index Nonlinearities in a Flint Glass Single-Mode Fiber
Authors: Takuya Suemura Takuya Suemura , Morimasa Ohtani Morimasa Ohtani , Ryuji Morita Ryuji Morita , Mikio Yamashita Mikio Yamashita
Published: October 2002

Change in the refractive index at around 630 nm in the femtosecond time region has been measured for the first time for a 75-wt% PbO-doped silica single-mode fiber with a highly sensitive, time-resolved interferometer using a heterodyne pump-probe technique. The result shows that the instantaneous response, nonlinear refractive index is 9.8 times as large as that of a conventional fused-silica fiber. This suggests that the PbO fiber is useful for efficient optical pulse compression and ultrafast optical switching in the visible and near-infrared wavelength region.
Formation of Elastic Cone-Like Microstructures on the Composite of Elastomer and Carbon Black by Excimer Laser Ablation
Authors: Ono Shigeyuki , Nakaoka Shinya , Wang Jun , Niino Hiroyuki , Yabe Akira
Published: October 2002

Laser ablation of composite material consisting of elastomer and carbon black was performed using a KrF excimer laser. Remarkable sensitization of polymer ablation with carbon black was observed and cone-like microstructures were produced on the ablated surface. The development of large cones was due to the aggregation of carbon-rich cones by repeated etching and melting upon further laser irradiation. The cone-like microstructures revealed a visco-elastic property that could be useful in the applications of sealing and packing materials.
Analysis of the Light Transmission of Cylindrical Doubly-Clad Waveguides with an Anisotropic and Metallic Outer Cladding
Authors: Jing-Hong Zhan Jing-Hong Zhan , Shiao-Min Tseng Shiao-Min Tseng
Published: October 2002

The light transmission in a weakly guided cylindrical step-index waveguide, containing a section of the double cladding with an anisotropic or metallic outer cladding, is theoretically investigated. Instead of formulating the dispersion relationship in the doubly-clad section, the throughput power of a guided ray in such a waveguiding structure is estimated from the viewpoints of the ray propagation and its tunneling phenomenon. Illustrated examples and calculations clearly show the filtering properties of the waveguide. Advantages of the present method and comparisons with other approaches are also discussed.
Raman Spectra of CuInSe 2 Thin Films Prepared by Chemical Spray Pyrolysis
Authors: Sho Shirakata Sho Shirakata , Hitoshi Kubo Hitoshi Kubo , Chihiro Hamaguchi Chihiro Hamaguchi , Shigehiro Isomura Shigehiro Isomura
Published: October 2002

Raman spectra have been investigated for CuInSe2 polycrystalline thin films prepared by chemical spray pyrolysis. The A
1 mode Raman peak at 174 cm-1, the dominant peak in CuInSe2 with a chalcopyrite structure, and a peak at 182 cm-1 have been observed. The A
1 mode peak is dominant for Cu-rich films and stoichiometric films deposited at high substrate temperature. On the other hand, the 182 cm-1 peak is dominant for In-rich films and stoichiometric films deposited at low substrate temperature. By comparing the Raman results with the X-ray diffraction measurements, the peak at 182 cm-1 is found to be characteristic of CuInSe2 with a sphalerite structure.
Magnetic Field-Induced Effects on the Melting Temperatures of Polymer Gels
Authors: Yoichiro Matsumoto Yoichiro Matsumoto , Isao Yamamoto Isao Yamamoto , Masuhiro Yamaguchi Masuhiro Yamaguchi , Yoshihiro Shimazu Yoshihiro Shimazu , Fumihiro Ishikawa Fumihiro Ishikawa
Published: October 2002

The gel-melting temperature was observed for aqueous agarose and aqueous methyl cellulose gels which were prepared under the influence of magnetic fields up to 5 T. The exposure to magnetic fields during gelation caused the melting temperature to increase in the agarose gels (+1.0 K for the 0.2 wt% gel) and to decrease in methyl cellulose gels (-3.5 K for the 0.4 wt% gel). The change in melting temperature was reduced with increasing polymer concentration and was saturated in magnetic fields below 3 T. Stable gel structures were constructed due to the exposure to magnetic fields.
Structural Study of an Al72Ni20Co8Decagonal Quasicrystal Using the High-Angle Annular Dark-Field Method
Authors: Pang Tsai Koh Saitoh
Published: October 2002

High-angle annular dark-field (HAADF) images of an Al72Ni20Co8decagonal quasicrystal have been taken for the first time. It has been found that the transition metals form pentagonal and star-shaped cluster columns with radii of about 0.4 nm. The atom-cluster columns with a 2 nm diameter of the alloy, which have been considered as the basic structural unit with decagonal symmetry so far, have been revealed to have no decagonal symmetry. These atom-cluster columns have been found to be decomposed into the pentagonal and star-shaped cluster columns, corresponding clusters existing in the Al13Fe4monoclinic approximant. The tiling of the pentagonal and star-shaped clusters has been found to agree with the rhombic Penrose lattice for an area with a diameter greater than 50 nm.
Ohmic Ignition of Alcohol-Ammonium Nitrate Mixture for Hot Light Gas Generation
Authors: Kazunari Ikuta Kazunari Ikuta
Published: October 2002

The theoretical considerations of the ohmic ignition of an alcohol-ammonium nitrate mixture for the generation of hot light gas are described in detail along with a suggested design for an accelerator.
Structure and Stress-Induced Alignment of a Hydrogen-Carbon Complex in Silicon
Authors: Yoichi Kamiura Yoichi Kamiura , Nobuaki Ishiga Nobuaki Ishiga , Yoshifumi Yamashita Yoshifumi Yamashita
Published: October 2002

We applied deep-level transient spectroscopy (DLTS) under uniaxial stress to study the structure and bonding nature of a hydrogen-carbon (H-C) complex in Si. The application of <111> and <110> compressive stresses split the DLTS peak into two as ratios of 1:3 and 2:2, respectively, which were the ratios of the low-temperature peak to the high-temperature peak. No splitting was observed under the <100> stress. These results indicate the trigonal symmetry of the H-C complex and the anti-bonding nature of its electronic state. We observed a stress-induced alignment of the complex at 250K for 50 min under a <110> stress of 1 GPa.
High-Definition Microscopy of Pressure-Induced NaCl-CsCl Transition in RbCl
Authors: Koji Shigematsu Koji Shigematsu , Yoshinori Takahashi Yoshinori Takahashi , Tsutomu Sawada Tsutomu Sawada , Ken'ichi Takemura Ken'ichi Takemura , Yoshihiro Taniguchi Yoshihiro Taniguchi , Seiji Sawamura Seiji Sawamura , Toshiyuki Tomobe Toshiyuki Tomobe , Kazunori Kawasaki Kazunori Kawasaki , Masato Koyama Masato Koyama
Published: October 2002

Both forward and backward phase transitions of RbCl were observed, in cases in which as-grown single crystals of RbCl were prepared even for obtaining a high-pressure phase by rearrangement of ions through the intermediary of the solution. Our high-definition microscopy revealed new characteristics of the dynamics of this well-known phenomenon: On compression, the NaCl-type single crystal was slowly transformed with retention of single crystallinity and without apparent change in crystal shape and size. Moreover, the reverse transition was totally destructive; the mother single crystal of CsCl-type broke into fragments. These characteristics are inconsistent with the widely accepted transition mechanism based on highly cooperative movement of ions.
Deep Interface States in SiO 2/p-type α-SiC Structure
Authors: Naoya Inoue Naoya Inoue , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroshi Yano Hiroshi Yano , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

Thermally grown SiO2/p-SiC interfaces were characterized by a high-frequency C-V measurement using a light illumination technique. A large negative flatband shift at room temperature in a p-type SiC MOS capacitor is caused by fixed charges in SiO2 near the interface and holes captured at deep interface states. The contribution of both components to the voltage shift could be separated by utilizing illumination. By illumination under the deep depletion condition, deep states emit holes and become neutral. Therefore, only fixed charges affect the voltage shift after the emission of holes from the deep states. From this method, the total deep state density was estimated to be 4∼6 ×1012 cm-2 and the effective fixed charge density, 1 ∼2 ×1011 cm-2, indicating that the flatband shift is mainly caused by holes trapped at deep interface states.
Transverse Mode Filtering and Spectral Purification Through Stimulated Raman Scattering
Authors: Yasuyuki Hirakawa Yasuyuki Hirakawa , Hidemasa Kanada Hidemasa Kanada , Totaro Imasaka Totaro Imasaka
Published: October 2002

Low-order transverse mode of dye laser emission was more efficiently converted into Stokes beams because of a high Raman gain coefficient, and the Stokes beams with near-TEM00 mode and good spectral purity were obtained from a multi-mode pump beam. High-order transverse mode remained and amplified spontaneous emission of the dye laser were removed by placing a pinhole at the beam waist, giving a flatter intensity distribution for the fundamental and Stokes emissions in the Raman spectrum.
Hydrogen Molecules in Defective Silicon
Authors: Fukata Naoki , Sasaki Shinichi , Murakami Kouichi , Ishioka Kunie , Nakamura Kazutaka , Kitajima Masahiro , Fujimura Shuzo , Kikuchi Jun , Haneda Hajime
Published: October 2002

Hydrogen molecules are formed in crystalline silicon treated with atomic hydrogen. We have investigated the effect of defects in silicon on the formation of hydrogen molecules. Raman measurements were taken on crystalline, microcrystalline and amorphous silicon after treatment with atomic hydrogen. A vibrational line of H2 was observed in crystalline and microcrystalline silicon after treatment with atomic hydrogen. The intensity of the vibrational line in microcrystalline silicon is approximately one fifth of that observed in crystalline silicon. No Raman signals due to H2 were detected in either amorphous Si:H or amorphous silicon produced by ion implantation. These results suggest that hydrogen molecules observed in hydrogenated crystalline silicon are trapped in the interstitial sites in nondamaged crystals of silicon.
Growth of Ga1-xBxN by Molecular Beam Epitaxy
Authors: Vezin Vincent , Yatagai Satoshi , Hiroyuki Shiraki Hiroyuki Shiraki , Satoshi Uda Satoshi Uda
Published: October 2002

Pseudobinary compounds of column III elements and nitrogen are semiconductors widely studied for optoelectronic applications. Ga1-
x

B

x

N compounds are considered to be prone to phase separation due to the large difference in bond length between B–N and Ga–N. However if a sufficient amount of boron can be incorporated to Ga1-
x

B

x

N compounds, lattice matching with substrates such as SiC, AlN and Ga1-
x

Al

x

N may be achieved. We used molecular beam epitaxy to grow Ga1-
x

B

x

N films on sapphire c faces with various values of x. Single-phase wurtzite Ga1-
x

B

x

N with x up to 4.56% has been obtained.
Scanning Tunneling Microscopy Study of C(2×4)-NO/Pt(001)
Authors: Moon-Bong Song Moon-Bong Song , Kazutaka Momoi Kazutaka Momoi , Masatoki Ito Masatoki Ito
Published: October 2002

A structure of NO adsorbed on a Pt(001)-hex R0.7° surface at 300 K was investigated by atomically resolved scanning tunneling microscopy (STM) in an ultra-high vacuum environment. STM images of NO on a Pt(001) surface at 300 K showed a simple c(2×4)-NO superstructure corresponding to a saturation coverage of 0.25. Our STM observation differed from the previous c(2×4) models for the NO adlayer with a saturation coverage of 0.5. At 90 K, extremely small and one-dimensionally grown domains of a quasi-c(2×4) adlayer were observed as clustered islands with a stripe structure of the bare Pt(001)-hex R0.7° surface.
Formation of ErP Islands on InP(001) Surface by Organometallic Vapor Phase Epitaxy
Authors: Bolotov Leonid , Tsuchiya Junji , Fujiwara Yasufumi , Takeda Yoshikazu , Arao Nakamura Arao Nakamura
Published: October 2002

First observation of ErP islands formed on InP(001) during Er-exposure by organometallic vapor phase epitaxy is demonstrated for 0.7–0.8 ML coverage. Different features of the surface morphology for Er-exposed InP are observed depending on substrate temperatures. While large islands (200–300 nm) are grown on the InP(001) surface at a substrate temperature of 530° C, small dots (17–30 nm) with the density of about 5×109 cm-2 are formed at 580° C. ErP islands are preferably grown along the [010] and [100] directions to decrease the lattice distortion.
Narrow Photoluminescence Line Width of Closely Stacked InAs Self-Assembled Quantum Dot Structures
Authors: Sugiyama Yoshihiro , Nakata Yoshiaki , Futatsugi Toshiro , Sugawara Mitsuru , Yuji Awano Yuji Awano , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

We report an effect of interval layer thickness in stacked InAs self-assembled quantum dot (QD) structures on photoluminescecnce (PL) characteristics focusing on thicknesses less than 3 nm. A drastic decrease in PL line width as narrow as 21 meV at 4.2 K was obtained with 2-nm interval layers. PL measurements show that the stacked structure forms an equivalent single QD structure which vertical size is extended effectively more than that of single layer QD. This attributes to the decrease of PL line width governed by the fluctuation mainly in the vertical direction. PL from higher order quantized states up to the 4th state are also clearly observed.
Sensitive Giant Magnetoresistive Sensor Using AC Bias Magnetic Field
Authors: Yamane Haruki , Kobayashi Juro Mita
Published: October 2002

A new sensitive magnetic sensor was developed by utilizing the giant magnetoresistance effect of spin-valve film. The sensor element was composed of a spin-valve layer patterned to a micro size, and a bias current layer which generates a square wave AC magnetic field. High sensitivity was attained using only the edge part of the step shape MR loop.
Sintering and Dielectric Properties of Ba2Ti9O20Microwave Ceramics by Glass Addition
Authors: Cheng Chien-Min , Cheng-Fu Yang Cheng-Fu Yang , Shi-Hong Lo Shi-Hong Lo
Published: October 2002

MgO–CaO–SiO2–Al2O3(MCAS) glass, which is fabricated by the sol-gel method, is selected as the sintering aid of Ba2Ti9O20ceramics. The effect of adding glass on the sintering and dielectric properties of Ba2Ti9O20ceramics is investigated. The crystalline phases of MCAS- Ba2Ti9O20ceramics are Ba2Ti9O20and cordierite. As the content of MCAS glass increases, the density curve is shifted to lower sintering temperature. For the densified MCAS- Ba2Ti9O20ceramics, the dielectric constants (at 1 MHz) decrease with increasing MCAS glass content.
Strain-Compensation Effect on the Reduction of Lattice Distortion in InGaAs/(In)GaAs(P) Strained Quantum-well Structures on GaAs Substrates
Authors: Hiramoto Kiyohisa , Toyonaka Misuzu Sagawa
Published: October 2002

InGaAs/InGaAsP strained quantum-well (QW) structures grown by metal-organic vapor phase epitaxy on (001) GaAs substrates were investigated using photoluminescence measurement and transmission electron microscopy. The lattice distortion in and near the QW structures caused by compressive strain in the InGaAs wells was reduced far below that of ordinary InGaAs/GaAs QW structures and the maximum number of QWs without cross-hatched patterns on the samples can be increased when tensile-strain InGaAsP barriers were introduced.
Formation of InAs Wires and Dots on Vicinal GaAs (110) Surfaces with Giant Steps by Molecular Beam Epitaxy
Authors: Torii Satoshi , Shim Byoung-Rho , Yasuda Haruyuki , Maehashi Kenzo , Shigehiko Hasegawa Shigehiko Hasegawa , Hisao Nakashima Hisao Nakashima
Published: October 2002

InAs are grown on vicinal GaAs (110) surfaces with giant steps using molecular beam epitaxy. Atomic force microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy show that uniform and well-aligned InAs wires and dots are formed on the facets at giant step edges due to the accumulation of InAs. This accumulation is only observed in a relatively high growth temperature range (580–600° C) and not at low temperatures.
Photoreflectance and C-V Measurement Investigations of Dry Etched Gate Recesses for GaInP/InGaAs/GaAs Pseudomorphic High Electron Mobility Transistors (HEMTs) Using BCl3/Ar Plasma
Authors: Chi-Wein Kuo Chi-Wein Kuo , Yan-Kuin Su Yan-Kuin Su
Published: October 2002

Photoreflectance (PR) spectroscopy and capacitance-voltage (C-V) measurements are used to characterize the surface damage caused by BCl3/Ar plasma in barrier layer of GaInP/GaInAs/GaAs pseudomorphic high electron mobility transistors (PHEMT). When the BCl3/Ar flow ratio is either lower or higher than 6:4, PR spectra indicate plasma causes damage such as nonradiative recombination centers, scattering centers and strain which lead to decreased signal intensity, broadened linewidth, and the spectral shift, respectively. The plasma-induced surface damage also results in a positive voltage shift of the C-V curve. By using a BCl3/Ar mixed gas, the positive voltage shift of the C-V curve is less than that of samples with pure BCl3. Both PR and C-V measurements are in good agreement. These results show that photoreflectance spectroscopy is a powerful, nondestructive tool for investigating surface damage and can be used to improve the performance of PHEMTs.