bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Spatial Cyclotron Subharmonic Resonances and Mirror Trapping of an Electron Beam by These Resonances
Authors: Sadamoto Yoshiro , Hijiya Makoto , Hagiwara Shigeo
Published: February 2005

A spatial cyclotron resonance and its subharmonic resonances are obtained from the measurement of an electron beam current passing through a magnetic mirror with a spatially modulated magnetic field. These resonances are also confirmed by solving the equation of motion in three magnetic configurations using a 6th-order Lunge-Kutta method. Mirror trapping of an electron beam by the resonances is shown. A remarkable result is found at the second subharmonic resonance.
Optical Activation of Er3+ Implanted in Silicon by Oxygen Impurities
Authors: Favennec P. N. , L'Haridon H. , Moutonnet D. , Salvi M. , Gauneau M.
Published: February 2005

Luminescence spectra and SIMS measurements of Er-doped silicon are presented in this paper. Luminescence was found to be stronger in Czochralski-grown Si crystals, known to contain up to 1018 cm-3 of oxygen center. Direct role played by oxygen impurities in the optical activation of the 1.54 µm luminescence was demonstrated by implanting oxygen into Er implanted layers in silicon at concentrations comparable to those of Er. Possible mechanisms of enhancement of photoluminescence are discussed.
Intersubband Absorption in In0.15Ga0.85As/Al0.35Ga0.65As Multiple Quantum Wells
Authors: Shakuda Yukio , Katahama Hisashi
Published: February 2005

Intersubband absorptions within pseudomorphic quantum wells of the conduction band in In0.15Ga0.85As/Al0.35Ga0.65As multiple layers have been studied with various well widths and doping concentrations. The band-offset ratio of the conduction band is estimated to be from 55% to 70% by the calculation of intersubband absorption energies, taking into account the strain effects, the doping effects, and the nonparabolic nature of the energy band.
Single-Crystal X-Ray Structure Analysis of New Oxide-Superconductor Bi2(Sr1-xLnx)2(Gd1-yCey)2Cu2O10+z
Authors: Nakai Izumi , Imai Katsuhiro , Arima Takahisa , Tokura Yoshinori , Asano Hajime , Takagi Hidenori , Uchida Shin-ichi , Beyers Robert , Torrance Jerry B.
Published: February 2005

The crystal structure of Bi2(Sr1-x
Ln
x
)2(Gd1-y
Ce
y
)2Cu2O10+z
(Ln=Gd with x=0.1, y=0.23 and z=0.16 or Ln=Ce with x=0.1, y=0.13 and z=0.16) was determined using the X-ray intensity data of a single crystal. The chemical composition was determined by electron microprobe analysis. The crystal data are as follows: orthorhombic, space group Cmmb, a=5.435(2), b=5.446(1), c=17.826(5) Å, final R factor R
w=0.053 for 640 independent observed reflections. The structure is composed of stacking of the Bi-O double layer, a Cu-O sheet of CuO5 pyramids, and the fluorite-like Ln2O2 layer. Sr is located between the Cu-O sheet and the Bi-O double layer. The crystal has a commensurate type superstructure with unit cell dimensions b×9 and c×2 of the subcell: a=5.426(7), b=49.06(2), c=35.66(2) Å. Precession photographs showed orthorhombic symmetry and systematic absences suggested condensed symbols C
*
c
* for the space group of the superlattice. The modulation of the structure was well reflected on the anisotropic motions of the thermal ellipsoids of the component atoms in the average structure.
Superconductivity in the Pb2Sr2-xLaxCu2Oz System
Authors: Sasakura Hiroyuki , Nakahigashi Kiyotaka , Minamigawa Shinnosuke , Nakanishi Shigemitsu , Kogachi Mineo , Fukuoka Nobuo , Yoshikawa Masatoshi , Noguchi Satoru , Okuda Kiichi , Yanase Akira
Published: February 2005

Superconductivity has been discovered in the new Pb-based copper oxide system of Pb2Sr2-x
La
x
Cu2O
z
. The maximum onset and zero resistivity temperature was about 38 K and 33 K, respectively. The ceramics had a tetragonal symmetry with a=0.5422 nm and c=1.2695 nm, which became an almost-single phase in the composition x=1.0.
Optical Pulse Shaping Using a Fourier-Transformed Hologram
Authors: Ema Kazuhiiro , Shimizu Fujio
Published: February 2005

An optical pulse-shaping technique using a Fourier-transformed hologram is reported. This technique permits the arbitrary manipulation of the amplitude and phase of the input pulse. We demonstrate the shaping of a picosecond pulse into asymmetric multipulses and into a square pulse.
Large Aperture Polarized Light Source and Novel Liquid Crystal Display Operating Modes
Authors: Belayev S. V. , Schadt M. , Barnik M. I. , Fünfschilling J. , Malimoneko N. V. , Schmitt K.
Published: February 2005

A wide aperture liquid crystal polarized light source (LC-PLS) is presented which converts unpolarized-into circular- and/or linearly polarized light with an efficiency better than 80%. Moreover, new operating modes for electro-optical field-effects on which liquid crystal displays (LCDs) are based are shown to increase the transmission of twisted nematic (TN)-LCDs by a factor of two. Besides, a 25% shift of the TN-LCD transmission-voltage characteristics towards lower voltages is achieved. One of the new, reflective LCD-operating modes is shown to avoid light absorption by thin film transistor structures in actively addressed LCD-projection systems. Within the bandpass region of the cholesteric liquid crystal filters the combination of LC-PLS with appropriate LCD-operating mode is shown to increase the transmission of LCD-projection systems three to five times compared with conventional LCD-projectors.
Generation of Continuous Short-Wavelength Waves by Soliton Breakup
Authors: Yamamoto Motokazu , Sakurai Akira
Published: February 2005

A continuous short-wavelength wave generator has been constructed by utilizing the breakup phenomenon of the water wave soliton. This wave generator is a new frequency up converter. Furthermore, it is suggested that an electromagnetic wave frequency up converter can be developed based on the same principle.
Infrared Characterization of Interface State Reduction by F2 Treatment in SiO2/Si Structure using Photo-CVD SiO2 Film
Authors: Nakamura Masakazu , Okuyama Masanori , Hamakawa Yoshihiro
Published: February 2005

IR-ATR and IR transmission spectra of photo-CVD SiO2 on Si have been measured to characterize the effect of F2 treatment on the interface formation. IR-ATR spectra show that the Si-H bonds at the interface are reduced remarkably by the F2 treatment. This reduction effect depends on the growth temperature, and the dependence is qualitatively similar to that of the interface states. IR transmission and XPS spectra show that the residual F in the SiO2/Si structure is not bonded to Si. It is considered from these measurements that the F2 treatment activates the Si surface to form tight Si-O bonds.
Ideal Crystal Growth from Kink Sites on a GaAs Vicinal Surface by Metalorganic Chemical Vapor Deposition
Authors: Fukui Takashi , Saito Hisao
Published: February 2005

(AlAs)1/2(GaAs)1/2 fractional-layer superlattices are grown on a (001) vicinal substrate by metalorganic chemical vapor deposition. The substrate is misoriented to [1̄10] by 1.92° and [110] by 0.10{
d
e
g
r
e
e}. A large surface area of the superlattice is observed by bright field transmission electron microscopy (TEM). The superlattice periods are uniform and no undulation is observed, which is the same quality as that of normal superlattices. The results suggest the ideal growth from a kink site occurs during MOCVD growth, and the distances between kink sites are equal.
Metalorganic Vapor Phase Epitaxial Growth of Lithium-Doped ZnS
Authors: Mitsuishi Iwao , Shibatani Junji , Kao Ming-Hui , Yamamoto Masahiro , Yoshino Junji , Kukimoto Hiroshi
Published: February 2005

Lithium-doped ZnS epitaxial layers have been grown on GaAs substrates by metalorganic vapor phase epitaxy, using cyclopentadienyllithium as the dopant. Low-temperature photoluminescence spectra have shown the presence of lithium acceptors in the grown layers. The electrical resistivity decreased with increasing sublimation temperature of lithium dopant. The lowest resistivity achieved was about 4×102 Ω·cm and the highest p-type carrier concentration was 7.5×1015 cm-3.
Formation of Thermally Stable Multilayered BSCCO Films with 2223, 2234 and 2245 Structures
Authors: Nakamura Keikichi , Sato Junichi , Ogawa Keiichi
Published: February 2005

The conditions to synthesize the thermally stable, multilayered BSCCO films with 2223, 2234 and 2245 structures have been investigated. It is shown that the films sputter-deposited at T
s=665°C became thermally stable and showed super-conductivity in their as-deposited state when the appropriate target composition and cooling process were chosen. However, the multilayered films decomposed partially or completely into the 2212+2201 or 2212 phase when the substrate temperature was about 20 to 45°C lower than the above condition.
A New Method of Estimating the Superconducting Volume Fraction in High-Tc Superconductors
Authors: Ando Yoichi , Akita Shirabe
Published: February 2005

A new method is proposed to estimate the superconducting volume fraction in a high-T
c oxide superconductor. It is based on mixed-state magnetization and calculated from the reversible portion of the magnetization curve in a high field range. The method is inherently free from the Meissner fraction ambiguity; therefore, it is more appropriate for the evaluation of high-T
c oxide than the conventional methods based on perfect diamagnetism.
Magnesium Oxide Thin Films Prepared by Chemical Vapor Deposition from Magnesium 2-Ethylhexanoate
Authors: Maruyama Toshiro , Shionoya Jun
Published: February 2005

Magnesium oxide thin films were prepared by a low-temperature atmospheric-pressure chemical vapor deposition method. The raw material was magnesium 2-ethylhexanoate, which is nontoxic and easy to handle. The deposition can be carried out in air. At a reaction temperature above 450°C, a highly [100]-oriented polycrystalline film can be obtained on amorphous substrates.
Third-Harmonic Generation in Highly Oriented Poly(2,5-dimethoxy-p-phenylenevinylene) Film Prepared by Use of the Langmuir-Blodgett Technique
Authors: Kamiyama Koji , Era Masanao , Tsutsui Tetsuo , Saito Shogo
Published: February 2005

Highly oriented poly(2,5-dimethoxy-p-phenylenevinylene) MO-PPV thin films were obtained by use of the Langmuir-Blodgett (LB) technique. In the MO-PPV LB films, MO-PPV chains formed uniaxial orientation along the dipping direction in addition to ordinary planar orientation due to the use of the LB technique. Anisotropy of third-harmonic generation was observed in the oriented LB film; third-order susceptibilities χ(3) in the directions parallel and perpendicular to the orientation axis were estimated to be 2.9×10-10 esu and 0.75×10-10 esu at the fundamental wavelength of 1.064 µm, respectively.
Single Target Sputtering of As-Grown Superconducting Bi(-Pb)-Sr-Ca-Cu-O Thin Films on MgO(100)
Authors: Hakuraku Yoshinori , Miyagi Daisaku , Higo Satoru , Ogushi Tetsuya
Published: February 2005

As-grown superconducting thin films of Bi(-Pb)-Sr-Ca-Cu-O have been prepared on MgO (100) at 620–720°C by dc magnetron sputtering using a single target. The targets used were Pb-free Bi3Sr2Ca2.2Cu3O
x
and Pb-doped Bi3Pb2Sr2Ca2.2Cu3O
x
in nominal compositions. The as-grown process with no annealing yields c-axis oriented superconducting thin films with zero resistivity above 70 K. The superconducting properties of the thin films were affected by the substrate temperatures during film growth. The c-axis lattice constant of the films was also controlled to the value of 24–37 Å by changing the substrate temperature. The best film showed zero resistivity at 76 K and a superconducting 37 Å phase. The critical current density was measured at 4.2 K with J
c=2×106 A/cm2.
A Defect-Induced Absorption Loss in ZrF4-Based Fluoride Glasses
Authors: Ohishi Yasutake , Kobayashi Kenji , Fujiura Kazuo , Terunuma Yukio , Takahashi Shiro
Published: February 2005

It is shown that there is a reduced species originating from LaF3 in ZrF4-based fluoride glasses, in addition to the well-known reduced zirconium. Absorptivity of reduced lanthanum for the induced absorption is measured. The influence of the induced absorption on the spectral attenuation is considered.
Preparation of Pb-Doped Bi-Sr-Ca-Cu-O Superconducting Thin Films Grown by Chemical Vapor Deposition
Authors: Natori Katsuaki , Yoshizawa Shun-ichi , Yoshino Junji , Kukimoto Hiroshi
Published: February 2005

Superconducting Bi-Pb-Sr-Ca-Cu-O(BPSCCO) thin films have been prepared on SrTiO3 (100) substrates at 830°C by chemical vapor deposition using triphenylbismuth, tetramethyllead (Pb(Me)4) and β-diketone metal chelates of Sr, Ca and Cu for metal sources. The Pb/(Bi+Pb) ratio was controllable up to 0.15 by the flow rate of Pb(Me)4. The presence of the high-T
c phase was confirmed from the X-ray diffraction pattern. The T
c end of the films increased from 71.2 K to 84.6 K with increasing Pb/(Bi+Pb) from 0 to 0.15.
In Situ Preparation of Superconducting Thick Films from Rapidly Quenched Bi-Sr-Ca-Oxide Films and Surface-Oxidized Cu Plate
Authors: Sung Tae-Hyun , Nakagawa Zenbe-e , Yoshimoto Mamoru , Koinuma Hideomi , Yoshimura Masahiro
Published: February 2005

Superconducting thick films of Bi2Sr2CaCu2O
y
are successfully prepared by in situ reaction between amorphous film of Bi2SrCaO
x
and CuO/Cu substrate. The film of Bi2SrCaO
x
with a 5 µm thickness reacted with the oxidized copper to yield (00l) oriented Bi2Sr2CaCu2O
y
films by heating at 820–850°C for 1–60 min in air. These films showed a superconductivity with the maximum T
c(end)=83 K obtained by heating in air at 855°C for 20 min. Similar superconductivity was obtained by heating thick films at 850°C for short periods such as 1 min.
High-Speed Intensity Modulation by Quantum-Confined Field Effect Combined with Modulation of Injection Current in Light-Emitting Triodes
Authors: Mukaiyama Keiji , Yamanishi Masamichi , Kan Yasuo , Ohnishi Takanori , Okuda Masahiro , Suemune Ikuo
Published: February 2005

A combination of the quantum-confined field effect with the modulation of current injection is, for the first time, demonstrated to result in high-speed switching of emission intensity in AlGaAs light-emitting triodes at room temperature. The switching scheme does not reply on changes in carrier population at all but purely on effects of the electric field on oscillator strength in the quantum well active layer of the device, in marked contrast to the modulation scheme in conventional light-emitting diodes. The response time of the luminescence intensity for a pulsed input voltage is observed to be completely free from recombination lifetime limitation. It is shown that the high-speed capability inherent in the field effect is not degraded by the modulation of current injection and that three-terminal operation is essential for the high-speed switching.
Electromigration Induced Step Bunching on Si Surfaces – How Does it Depend on the Temperature and Heating Current Direction?
Authors: Stoyan Stoyanov Stoyan Stoyanov
Published: February 2005

Recently reported data for an influence of the heating current direction on the micromorphology of Si surfaces have been analyzed on the basis of the hypothesis for electromigration of Si adatoms. The results provide a reasonable explanation of the observed step bunching on the (111) Si surface, which occurs either at moderate or at high temperature depending on the direction (step up or step down) of the heating current. The confrontation with the experimental data results in a negative effective charge of the Si adatoms. The formation of major and minor domains on (001) Si vicinal surfaces under low temperature annealing is also interpreted in accordance with the obtained theoretical results. The force acting on the Si adatoms is estimated to be 0.8×10-16 N and can be created by an electric field of 5 V/cm if the effective charge of an adatom is equal to the elementary electric charge.
Displacement Current Generated by Photo-Induced Molecular Switching in a Single Monolayer
Authors: Iwamoto Mitsumasa , Noguchi Tetsuya , Hiromasa Fuwa Hiromasa Fuwa , Yutaka Majima Yutaka Majima
Published: February 2005

The optical molecular switching in single monolayers containing azobenzene derivatives deposited on solid substrates due to photo-induced cis-trans isomerization was detected by using a displacement current-measuring technique. The reversible displacement current generation was found to be sustained by the alternative applications of UV light and visible light, whereas the current generation was never initiated by the successive irradiation of UV or visible light. Finally, we concluded that the technique developed here will be used in future molecular electronic technologies.
The Quality of the Illumination for a Spherical Capsule Enclosed in a Radiating Cavity
Authors: A. Caruso A. Caruso , C. Strangio C. Strangio
Published: February 2005

The implosion of spherical capsules by the incoherent X-rays emitted from surrounding hot high-Z walls seems to be a scheme relevant to inertial confinement fusion. In this paper the quality of the illumination for a spherical capsule enclosed in an axisymmetric radiating cavity is considered for the two extreme cases of given, (optically) thick or thin, non-uniform, emitting cavity surface layer.
If the specific intensity on the radiating surface is represented by an expansion in Legendre polynomials, it is found, for spherical radiating cavities, that the n-term contribution to the power density upon the capsule factorizes as the product of a function of the position on the capsule surface, times a function f(n, x) of its radius x. Furthermore, it is found that values of x may exist for which f(n, x)=0, this being true both for thick and thin modeling with values of x almost the same. Simple criteria to get a given degree of uniformity are suggested.
The effects of the cavity shape on the illumination quality have been also studied as a function of the cavity aspect ratio for spherical capsules enclosed in ellipsoidal cavities (oblate or prolate).
X-Ray Focusing with Elliptical Kirkpatrick-Baez Mirror System
Authors: Uchida Yoshio Suzuki
Published: February 2005

Focusing Properties of a grazing-incidence mirror system are tested using a monochromatized synchrotron radiation X-ray source. The optical system employs two mirrors, each of elliptical cylinder shape, arranged in a crossed-mirror geometry (Kirkpatrick-Baez configuration) and generates a demagnified image of a 100-µm-diameter pinhole placed upstream in the beamline as the X-ray source. Edge-scan profiles show the focused spot size at half-maximum of about 1.7 µm×3.8 µm at a wavelength of 2.3 Å. In two-dimensional scanning of test patterns, a fine pattern of a 0.6 µm line and 0.6 µm space was resolved.
Population of the Metastable State of Yb I by an Electric Discharge
Authors: Jin Wei-Guo , Horiguchi Takayoshi , Wakasugi Masanori , Takashi Hasegawa Takashi Hasegawa , Wei Yang Wei Yang
Published: February 2005

An atomic beam oven of a discharge type is constructed and the performance in populating a metastable state of Yb I is examined. The relative populations of the ground state 4f
146s
21
S
0 and the metastable state 4f
135d6s
2 (7/2, 3/2)5 of Yb I are measured for the first time by the laser-induced fluorescence method. It is found that the population of the metastable state increases with the discharge current and that of the ground state decreases to 30%. The method is also applicable for other elements.
The δ-Doped In0.25Ga0.75As/GaAs Pseudomorphic High Electron Mobility Transistor Structures Prepared by Low-Pressure Metal Organic Chemical Vapor Deposition*
Authors: Chang C. Y. , Lin W. , Hsu W. C. , Wu T. S. , S. Z. Chang S. Z. Chang , C. Wang C. Wang
Published: February 2005

The (800 Å)GaAs/In0.25Ga0.75As/(0.5 µm) GaAs strain layers with δ-doping in the GaAs cap layer were fabricated without using AlGaAs layers. Triethylgallium (TEG), trimethylindium (TMI), arsine (AsH3) and silane (SiH4) were used as the sources and dopants in these structures grown by the low-pressure metalorganic chemical vapor deposition (LP-MOCVD) technique for the first time to study these structures. The δ-doping was obtained by a stop-growth process by which a very thin and heavily doped layer (1.86×1013 cm-2) can be realized. For the (δ-doped) GaAs/In0.25Ga0.75As/GaAs high electron mobility transistor (HEMT) structures, the concentration of two-dimensional electron gas (2-DEG) and the Hall mobilities were investigated. Experimental results show that a structure with (80 Å) In0.25Ga0.75As as the active channel and with a 70 Å spacer layer revealed the highest 2-DEG concentration and mobility product of 5.5times1016 V-1·s-1 at a temperature of 77 K. These structures are easy to achieve by the LP-MOCVD mechod and are promising for high-performance field effect transistors (FETs).
Tunneling Spectroscopy of Resonant Transmission Coefficient in Double Barrier Structure
Authors: Masahiro Tsuchiya Masahiro Tsuchiya , Hiroyuki Sakaki Hiroyuki Sakaki
Published: February 2005

It is theoretically pointed out that the tunneling spectroscopy technique offers us a method to evaluate the resonant tunneling transmission coefficients of double barrier structure: the transmittance function is proportional to the second derivative of I-V characteristics. Peaked transmittance of the first resonance level was, indeed, measured in an AlAs(2.3 nm)-GaAs(5.4 nm)-AlAs(2.3 nm) double barrier structure. It was found that the measured half width at half maximum of the peak was 15 meV which is 220 times larger than a predicted value (∼69 µeV) calculated with a simple Kronig-Penny type model, while the peak height was reduced from unity by a factor of 950. The width is, however, in good agreement with width of photoluminescence peak from the structure. The results imply presence of energy broadening mechanisms in the resonant tunneling structure.
Metal Organic Molecular Beam Epitaxy Growth of Ga0.5In0.5P/GaAs Quantum Well Structures
Authors: Garcia Jean Charles , Philipe Philipe , Maurel Maurel , Philippe Bove Philippe Bove , Jean Pierre Hirtz Jean Pierre Hirtz
Published: February 2005

High-quality GaAs/GaInP single and multi-quantum-well structures have been grown by metal organic molecular beam epitaxy. Wells as thin as 10 Å have been grown exhibiting confinement energies exceeding 310 meV. The influence of growth interruption at both interfaces has been investigated by low-temperature photoluminescence. The critical role of the relative incorporation kinetics of arsenic and phosphorus atoms in determining the nature of the normal and inverted interfaces defining GaAs quantum wells is shown. An excitonic type recombination is evidenced by low-temperature-dependence photoluminescence measurements. Carrier capture is shown to be very efficient, even for the narrowest wells studied.
Elastic Anomalies of High-TcSuperconductor YBa2Cu3O7-xbetween 77 K and 300 K
Authors: Kamioka Hiroaki , Nobuyuki Okuda Nobuyuki Okuda , Shoji Nitta Shoji Nitta
Published: February 2005

The shear and compressional wave velocities and attenations in the high-Tcsuperconductor YBa2Cu3O7-xare accurately determined by the pulse transmission method using a “dual-type cell” at temperatures between 77 K and 300 K. The temperature dependence of shear wave velocities shows the change of three steps. Three attenuation peaks (shear wave) appear at about 80, 170 and 210 K. The peaks correspond to the steps of shear wave velocity. From measured ultrasonic data, the elastic and inelastic properties of aggregates on YBa2Cu3O7-xare reported, and are discussed on the basis of previous reports.
Preparation and Characterization of YBa2Cu3O2-δFilms Containing an Excess Amount of Cu by Chemical Vapor Deposition
Authors: Higashiyama Kazutoshi , Ushida Takahisa , Higa Hiroyuki , Izumi Hirabayashi Izumi Hirabayashi , Shoji Tanaka Shoji Tanaka
Published: February 2005

YBa2Cu3O7-δfilms containing an excess amount of Cu were prepared on MgO(001) at 650-750°C by chemical vapor deposition using β-diketone metal chelates. In the films prepared at the low temperatures of 650°C and 700°C, the degree ofc-axis orientation was enhanced with increase of the Cu content from Y:Ba:Cu=1:2:3 to 1:2:4, and the films with Cu-rich content showed higherTcvalues than the films close to the stoichiometric composition. At the higher temperature of 750°C, a supplied excess of the Cu element affected the in-plane alignment of the grains and critical current density.
Reaction-Bonded Boron Nitride-Aluminum Nitride Ceramic Composites
Authors: Kanai Takao , Kei Tanemoto Kei Tanemoto , Hiroshi Kubo Hiroshi Kubo
Published: February 2005

Hexagonal boron nitride-aluminum nitride (h-BN-AlN, 75-25 wt%) ceramic composites are synthesized by reaction bonding. Metallic component-free, relatively dense composites are obtained by using h-BN and Al as starting materials and by optimizing sintering conditions. In comparison with reaction-bonded BN, higher bending strength, 98 MPa, and higher thermal conductivity, 66 W/(m·K), are attained for a Y2O3-added BN-AlN composite. A low thermal expansion coefficient of 2.6×10-6/K is also achieved.
Time Response of Liquid Crystals Aligned on Ferroelectric Layers
Authors: Hitoshi Mada Hitoshi Mada
Published: February 2005

A new mode of liquid crystal display which has a fast response time is proposed. Using a solid ferroelectric material as an aligning layer, a ferroelectric liquid crystal director is controlled from the surface by an external electric field. In a preliminary experiment, guanidine aluminium sulfate hexahydrate is used as the aligning layer, and a response time half that of the conventional aligning method is obtained.
Autofocusing System of Optical Microscope Utilizing Electrostrictive Actuators
Authors: Suyama Ryuji , Tanemoto Kei , Kobayashi Yoshinari , Yajima Masao
Published: February 2005

A precise positioning table equipped with a pair of electrostrictive actuators and hinged levers has been manufactured. A good displacement-vs-applied-voltage relationship has been achieved with an 18-µm stroke and small hysteresis. An autofocusing system of an optical microscope utilizing the table has been assembled. The system has high precision (0.035 µm) of repeated positioning and can focus a microscope with ×100 magnification of the objective lens.
Dependence of Au- Production upon the Target Work Function in a Plasma-Sputter-Type Negative Ion Source
Authors: Okabe Yushirou , Sasao Mamiko , Yamaoka Hitoshi , Wada Motoi , Junji Fujita Junji Fujita
Published: February 2005

A method to measure the work function of the target surface in a plasma-sputter-type negative ion source has been developed. The method can determine the work function by measuring the photoelectric current induced by two lasers (He-Ne, Ar+ laser). The dependence of Au- production upon the work function of the target surface in the ion source was studied using this method. The time variation of the target work function and Au- production rate were measured during the cesium coverage decrease due to the plasma ion sputtering. The observed minimum work function of a cesiated gold surface in an Ar plasma was 1.3 eV. At the same time, the negative ion production rate (Au- current/target current) took the maximum value. The negative ion production rate indicated the same dependence on the incident ion energy as that of the sputtering rate when the work function was constant.
Laser Interferometer Instrumented in a Disk Antenna for Gravitational Radiation
Authors: Tsubono Kimio , Norikatsu Mio Norikatsu Mio , Akihiko Mizutani Akihiko Mizutani
Published: February 2005

Disk antennas combined with a laser interferometer as a displacement transducer can be made into highly sensitive, wideband detectors for gravitational radiation. The proposed detector system, which operates at room temperature, has a minimum detectable amplitude of gravitational radiation, h
min=4×10-18, and a detection bandwidth of 80 Hz at around 1.2 kHz. The expected performance of the laser transducer is calculated and the feasibility of this type of detector for gravitational radiation is shown.
Reflection High-Energy Electron Diffraction Studies of Vicinal Si(111) Surfaces
Authors: Hibino Hiroki , Shinoda Yukinobu , Yoshihiro Kobayashi Yoshihiro Kobayashi , Kiyomasa Sugii Kiyomasa Sugii
Published: February 2005

Analysis of the reflection high-energy electron diffraction (RHEED) patterns from the vicinal Si(111) surfaces misoriented to [112̄] shows that step bunching takes place on the surface, and the surface breaks up into (111) and (331) facets. A previously unreported superstructure is found on the (331) facet. From the temperature dependence of the diffraction spot positions, this superstructure and the 7×7 structure on the (111) facet are shown to cause the reconstruction-induced faceting.
Preparation of a-Si and a-Si-Alloy Films Using an Ion-Gun Chemical Vapor Deposition Method
Authors: Haku Hisao , Sayama Katsunobu , Matsuoka Tsugufumi , Tsuda Shinya , Nakano Shoichi , Michitoshi Ohnishi Michitoshi Ohnishi , Yukinori Kuwano Yukinori Kuwano
Published: February 2005

As a new amorphous-silicon (a-Si) fabrication technique, an ion-gun chemical vapor deposition (CVD) method, in which ions add energy to surface reactions, has been developed. The ion source employed in this gun is of the hot cathode type with a multicapillary anode which creates a collimated gas flow. A-Si:H and a-Ge:H films, fabricated at the substrate temperature of 130°C, show low dihydride bond density and high photosensitivity (4.0×105 at E
opt∼1.95 eV and 5.1 at E
opt∼1.03 eV, respectively). In addition, a double ion-gun CVD method, for which the energy of two kinds of ion species can be independently controlled, has been developed for fabricating high-quality a-Si-alloy films. Highly photoconductive a-SiGe:H films with low optical gaps (<1.3 eV) were obtained using this fabrication method.
Near-Infrared Transmission Measurement of EL2 Concentration in Semi-Insulating GaAs Wafers with a Laser Diode (λ=1.3 µm)
Authors: Pan Ci-Ling , Hsiao-Hua Wu Hsiao-Hua Wu , Tzung-Rue Hsieh Tzung-Rue Hsieh
Published: February 2005

We demonstrated a near-infrared transmittance setup for EL2 concentration mapping in undoped semi-insulating (SI) GaAs wafers. The light source was a power-stabilized laser diode (λ=1.3 µm) operating in the light emitting diode (LED) mode. The sensitivity of the apparatus was as low as 1014 cm-3 for typical commercial wafers 350 µm in thickness.
Properties of Titanium Nitride Films for Barrier Metal in Aluminum Ohmic Contact Systems
Authors: Hara Tohru , Yamanoue Akira , Iio Hiroki , Inoue Ken , Nakamura Gen Washidzu
Published: February 2005

Properties of titanium nitride (TiN) films deposited by reactive sputtering and dc magnetron sputtering from composite target are studied. In the as-deposited films, a TiN (200) grain, which is the lowest energy grain and is dominant in bulk TiN, is grown in films from composite target. A resistivity of 44 µΩ-cm is attained. These results show that high quality TiN films can be deposited by dc magnetron sputtering employed TiN composite target. However, a TiN (111) grain is grown in TiN films by the nitridation of Ti. Nitridation of a reactively sputtered TiN film in ammonium is also studied. The TiN films deposited from composite target and formed by the nitridation of titanium show good barrier performance in Al-Si/TiN/Si Ohmic contact.
Mechanism for Initial Stage of Selective Tungsten Growth Employing a WF6 and SiH4 Mixture
Authors: Itoh Hitoshi , Kaji Naruhiko , Watanabe Toru , Haruo Okano Haruo Okano
Published: February 2005

Precise control of the interface reaction between adsorbates and the solid surface is now becoming a key issue for thin film growth technology. In this paper, the importance of electronic interaction in selective thin film growth has been demonstrated for the first time for the growth of tungsten films. It has been found that the dissociation of adsorbed molecules due to electron transfer from the substrate plays a crucial role in realizing the selectivity of tungsten growth.
Effect of Gas Species on the Depth Reduction in Silicon Deep-Submicron Trench Reactive Ion Etching
Authors: Sato Masaaki , Shin'ichi Kato Shin'ichi Kato , Yoshinobu Arita Yoshinobu Arita
Published: February 2005

In silicon deep-submicron trench reactive ion etching (RIE), a clearly larger micro-loading effect is found in fluorinated gas than in chlorinated gas. To elucidate the gas effect, a model experiment is carried out in Cl2 and SF6. Etched depth dependence on pattern width is also calculated considering both shadowing effect and surface migration of etching species. Based on the results, it is revealed that the micro-loading effect is caused by: (1) decreasing etching species concentration on the trench bottom with increasing trench depth and/or decreasing trench width, and (2) larger change in etch rate with the change in etching species concentration is in fluorinated gas than in chlorinated gas. It is also noted that adoption of a heavier halogen for the etching gas offers one way to eliminate the micro-loading effect because ion-assisted etching is dominant in heavier halogen etching.
Low-Temperature Fluorination of GaAs Surface by CF4 Plasma
Authors: Iida Masahiro , Hiromasa T. Kaibe Hiromasa T. Kaibe , Tsugunori Okumura Tsugunori Okumura
Published: February 2005

The GaAs surface was fluorinated at low temperatures in CF4 plasma. The constitution and the composition of the formed films as functions of the substrate temperature and exposure time were analyzed by X-ray photoelectron spectroscopy. The fluoride films whose thickness increased with the substrate temperature consisted of gallium oxyfluoride and free As. We have also examined the influence of the surface treatment of GaAs substrates as well as the capping layer on the fluoride films. The sulfur treatment delayed the initiation of fluorination, and a-Si:H capping layer prevented free As from evaporating out.
In Situ Monitoring of GaN Growth Using Interference Effects
Authors: Shuji Nakamura Shuji Nakamura
Published: February 2005

The interference effect was observed as an oscillation of the intensity of the transmitted IR radiation through the epitaxial film from the carbon susceptor during GaN growth using an IR radiation thermometer in metalorganic chemical vapor deposition (MOCVD). The IR radiation transmission intensity (IR-RTI) oscillations in GaN growth with and without an AlN buffer layer were studied in detail. The amplitude of the oscillation decreased with increasing thickness due to the thickness fluctuation of the growing GaN film within the measured spot area. In GaN growth with the AlN buffer layer, a very strong oscillation was observed because the surface morphology was much improved by the prior deposition of the AlN buffer layer. The sharp drop of the IR-RTI, which was attributed to the generation of the island growth of GaN around the nucleation site of the AlN buffer layer, was observed at a thickness of about 0.3 µm.
High Schottky Barriers between Amorphous-Si-P Alloy and P-Type Gallium Arsenide
Authors: Toshio Ogino Toshio Ogino
Published: February 2005

Schottky barriers of as high as 0.75 V are formed between p-type GaAs and amorphous Si-P alloy films. These high barriers are probably caused by P atoms on the GaAs surface. Because this contact is temperature-stable and easily formed simply by conventional chemical vapor deposition (CVD), it is suitable for fabrication of GaAs complementary metal-semiconductor field effect transistors (MESFETs).
Phase-Change Optical Disks with High Writing Sensitivity Using a-SiN:H Protective Films Prepared by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition
Authors: Sugiyama Yasuyuki , Yamazaki Hiroki , Susumu Fujimori Susumu Fujimori , Iwao Hatakeyama Iwao Hatakeyama
Published: February 2005

Hydrogenated amorphous silicon nitride (a-SiN:H) films prepared by electron cyclotron resonance plasma chemical vapor deposition (ECR-PCVD) technique are applied as the protective layers of phase-change optical disks. The properties of protective films and the disk structure are investigated with an aim toward improving the writing sensitivity and overwrite repeatability. The writing laser power required to obtain a sufficient carrier-to-noise ratio (C/N) of 53 dB can be as low as 11 mW at a linear velocity of 10 m/s. The erasability is more than 26 dB, the power tolerance is about 3 mW, and overwrite repeatability is 106 cycles. This is attributed to the superior protective film properties such as decreased thermal conductivity and excellent surface flatness.
Kβ X-Ray Emission Band and K X-Ray Absorption-Edge Structure of Sulfur in Layered Transition-Metal Compounds TiS2, ZrS2and HfS2
Authors: Sugiura Chikara , Shoji Shizuko , Kojima Shinjiro
Published: February 2005

The sulfur-Kβ emission spectra in fluorescence from TiS2, ZrS2and HfS2are measured with a high-resolution two-crystal vacuum spectrometer. The emission spectra are presented along with available XPS spectra of the valence bands of these disulfides and the sulfur-Kabsorption-edge spectra reported previously. TheKβ-emission andKabsorption-edge spectra are compared with the XPS spectra, UPS spectra, optical-gap data and energy-band calculations of the compounds. The relative intensities of the absorption peaks at theKedges are shown to be related to the degree of covalent mixing of the metaldand sulfur 3pstates.
Free-Volume-Dependent Atomic Diffusion in Compositionally Modulated Amorphous Co-Zr Films
Authors: Tadashi Mizoguchi Tadashi Mizoguchi , Masakatsu Murata Masakatsu Murata
Published: February 2005

Atomic interdiffusion in compositionally modulated amorphous Co-Zr films was investigated by means of in situ X-ray diffraction measurements during successive isothermal annealing. The results were analyzed as free-volume-dependent atomic diffusion and activation-type temperature dependence of both the atomic diffusion coefficient, and the annihilation rates of free volume were confirmed with the activation energy Q
D=8.84(±0.41)×104 J/mol and Q
A=3.77(±0.96)×104 J/mol, respectively.
Formation of Herringbone Structure with Davydov Splitting in Cyanine Dye-Adsorbed Langmuir-Blodgett Films
Authors: Saito Kazuhiro , Ikegami Keiichi , Kuroda Shin-ichi , Yuka Tabe Yuka Tabe , Michio Sugi Michio Sugi
Published: February 2005

Interface-adsorbed complex Langmuir-Blodgett (LB) films of arachidic acid and a water-soluble cyanine dye were fabricated using the diffusion-adsorption method. Formation of an H-aggregate with absorption band split was observed in the LB film. This split is assignable as Davydov splitting, which is characterized as the split of the band into two bands, whose transition moments are orthogonal to each other, due to formation of herringbonelike aggregates. The estimation of the molecular arrangement in the aggregate was performed based on Davydov's theory and the extended dipole model.
A Confinement-Collector GaAs Switching Device Prepared by Molecular Beam Epitaxy
Authors: Liu Wen-Chau , Der-Feng Guo Der-Feng Guo , Yeong-Shyang Lee Yeong-Shyang Lee
Published: February 2005

A new GaAs switching device with AlGaAs confinement collector structure has been demonstrated. An interesting S-shaped negative-differential-resistance (NDR) phenomenon, originating from the impact ionization at the GaAs intrinsic layer and the screening effect of acceptors at the p
+ base region, is observed. From the experimental results, it is known that the temperature variation plays an important role in the transport characteristics. Furthermore, the significant control voltage ratio, V
S/V
H, of the studied structure introduces a good potential for switching circuit applications.
Pressure Dependence of the Formation of YBaCuO Films by Chemical Vapor Deposition
Authors: Lee Hee-Gyoun , Park Joung-Shik , Shin Hyung-Shik , Kim Chun-Young , Chan-Joong Kim Chan-Joong Kim , Dong-Yeon Won Dong-Yeon Won
Published: February 2005

YBaCuO films were prepared on MgO(100) single-crystal substrates at 850°C under various pressures by the chemical vapor deposition method. The films showed superconductivity above liquid nitrogen temperature (T
c,0=81∼84 K). Faster growth of films that accompanied the formation of a porous microstructure was observed as the pressure was reduced.
Yield of Ion-Induced Secondary Electrons from Single Crystal
Authors: Hasegawa Masataka , Fukuchi Tooru , Susuki Yasuhumi , Fukui Shouichi , Kenji Kimura Kenji Kimura , Michihiko Mannami Michihiko Mannami
Published: February 2005

Anomalies in the yield of ion-induced secondary electrons from single-crystalline target are studied. They are (1) disappearance ofchannelling dips in the angular distribution of the yield of secondary electrons in MeV light ion channelling, and (2) an increase of the yield at angle of incidence on a surface smaller than about 10°. These are interpreted in terms of ion trajectories affected by crystal periodicity and effective mean escape length for secondary electrons in a solid.
Polyacetylene Metal-Semiconductor Field-Effect Transistors
Authors: Chen Ying-Chung , Cheng Chien-Chuan , Mao-Hsiung Chen Mao-Hsiung Chen , Kuang-Chin Huang Kuang-Chin Huang
Published: February 2005

Planar and sandwich types of polyacetylene metal-semiconductor field-effect transistors (MESFETs) have been fabricated. The current-vs-voltage (I-V) characteristics show that both types of MESFETs are depletion-mode transistors with low transconductances of about 10-6-10-7s. Channel modulation has been observed in both types of transistors; however, pinch-off cannot be found even at the drain voltage of up to about -30 V. The performances of both types of MESFETs have been compared and the effects on the performance of the transistor have been discussed.
Improvement in Spatial Resolution of Infrared Scanning Internal-Photoemission Microscope
Authors: Kenji Shiojima Kenji Shiojima , Tsugunori Okumura Tsugunori Okumura
Published: February 2005

The spatial resolution of the infrared scanning internal-photoemission microscope has been improved to be less than 5 µm. This was achieved by making use of a single mode fiber as the filter for the laser beam emitted from the laser diodes. The wavelength variation by the temperature control of a “single” laser diode is sufficient for determining the Schottky barrier height.
(Pb, La)(Zr, Ti)O3 Films by Multiple Electrophoretic Deposition/Sintering Processing
Authors: Sugiyama Shinichi , Akira Takagi Akira Takagi , Kaoru Tsuzuki Kaoru Tsuzuki
Published: February 2005

(Pb, La)(Zr, Ti)O3 films were prepared by multiple (electro-phoretic deposition/sintering) cycles, using fine crystalline powders, acetone, nitrocellulose and HNO3 as suspensions. Dense, strong films having a final thickness of 15∼25 µm were formed reproducibly on platinum substrates. Due to tight contact between the film and rigid substrate, during firing, lattice constants of sintered films were 0.3∼0.5% longer than those of bulk with the same composition. Reflecting these lattice expansions, the Curie temperature of sintered films shifted to higher temperature as compared to that of bulks with the same composition. All films with the composition 8/65/35 and 9/65/35 are ferroelectric and thus exhibit pyroelectric, and piezoelectric activities. These characteristics of the films are modified from those of the bulk form by crystal lattice distortion.
Growth and Properties of PbTiO3 Thin Films by Photoenhanced Chemical Vapor Deposition
Authors: Katayama Takuma , Fujimoto Masashi , Masaru Shimizu Masaru Shimizu , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

The photoenhanced chemical vapor deposition (CVD) of PbTiO3 thin films was carried out using tetraethyl lead, titanium tetraisopropoxide and nitrogen dioxide. The use of NO2 and UV light irradiation during the growth run affected the crystalline quality and dielectric properties of films. The photodeposited films with a perovskite structure were obtained on sapphire at substrate temperatures above 530°C. In this study, it was found that the photodissociation of NO2 played an important role in decreasing the growth temperature. The step coverage characteristics of films were also investigated.
Properties of Piezoelectric Ceramics Sintered in Reducing Atmosphere
Authors: Kunihiro Nagata Kunihiro Nagata
Published: February 2005

Antireduction piezoelectric ceramics were fabricated by adding excess 3 at % of divalent metal ion Sr or Ba to the A site and 0.3∼1.0 wt% of MnCO3 and glass for lead perovskite material. Piezoelectric K
p and d
31, constants of specimens sintered under a reducing atmosphere of P
0=10-9 MPa were about 45% and about 200×10-12 m/V, respectively, and bending strength was about 760 kg/cm2. Employing this material, we should be able to fabricate multilayer piezoelectric ceramic devices where Cu or Ni can be used as the internal electrode.
Piezoelectric Properties of 0-3 Composite of Polymer and Ceramic Powder Mixture of PZT and PbTiO3
Authors: Hisao Banno Hisao Banno , Kohji Ogura Kohji Ogura
Published: February 2005

Hydrostatic piezoelectric constants of composites consisting of polymer and ceramic powder mixture of PZT and PbTiO3 with different average ceramic particle sizes (PZT/PT=7.5 µm/3.3 µm) took enhanced values in the PZT-rich region of the ceramic powder mixture at 70 ceramic volume percent. The reasons are discussed in this paper.
Ultrasonic Motor Utilizing Elastic Fin Rotor
Authors: Uchiki Tatsuya , Nakazawa Toru , Nakamura Kentaro , Minoru Kurosawa Minoru Kurosawa , Sadayuki Ueha Sadayuki Ueha
Published: February 2005

An ultrasonic micromotor which has vibration conversion `elastic fins' in the rotor is proposed and constructed for trial. The motor, which is 5 mm in diameter, has proved to work quite well, and this suggests the possibility of further miniaturization of the motor. The principle and experimental evaluations of the characteristics of the motor are presented.
Dielectric Properties of Lead Alkaline-Earth Zirconate at Microwave Frequencies
Authors: Kato Junichi , Hiroshi Kagata Hiroshi Kagata , Keiji Nishimoto Keiji Nishimoto
Published: February 2005

Dielectric properties of alkaline-earth-substituted PbZrO3 ceramics up to microwave frequencies were investigated. Although there were no preferable characteristics in the Ba- or Sr-substituted system, the ceramics in a (PbCa)ZrO3 system showed not only high dielectric constants in the range of 100 to 118, but also high Q values of 1000 to 1150 and small temperature coefficients of resonant frequency of 0 to 30 ppm/ °C. The crystal structure of the Ca-substituted ceramics was also investigated by X-ray powder diffraction. The structure changed from PbZrO3-type orthorhombic to CaZrO3-type orthorhombic through cubic and rhombohedral with increasing Ca substitution. Coaxial dielectric resonators made of the selected above material had Q values in the range of 430 to 450 at the 900 MHz band.
Optical Logic Element Using Ferroelectric Liquid Crystal with Electrical Feedback
Authors: Moritake Hiroshi , Tagawa Akira , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

Optical bistability in surface-stabilized ferroelectric liquid crystal (SSFLC) with an electrical feedback has been studied. The hysteresis in the transmission-voltage curve which is characteristic of SSFLC is found to contribute to the expansion of the optical bistable region. Dynamic characteristics of the switching between optical bistable states by an incident light pulse have also been studied. A new multilogic element with both OR and AND functions which can be selected by controlling the duration of the reset light pulse can be realized.
BaTiO3 Single Crystal Growth by Travelling Solvent Floating Zone Technique
Authors: Jun Furukawa Jun Furukawa , Takeyo Tsukamoto Takeyo Tsukamoto
Published: February 2005

Single crystals of BaTiO3 were grown from the ceramic rods doped with Sr (1.0-3.0 mol%) by a travelling solvent floating zone technique. The grown crystals were slightly opaque yellow. The ferroelectric phase transition occurred at 129°C in a crystal doped with Sr (1.0 mol%). The X-ray diffraction patterns at room temperature were well fitted to those of tetragonal BaTiO3. Ferroelectric properties of grown crystals were examined.