bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Cubic Boron Nitride Film on Si with Boron Buffer Layers
Authors: Okamoto Masaki , Yokoyama Haruki , Osaka Yukio
Published: February 2005

The c-BN (cubic BN)/BN
X
/B/Si structure was formed using plasma CVD techniques. In contrast with the direct growth of c-BN films, the adherence of the structure on Si was entirely satisfactory. The characterization of buffer layers (BN(X=0.6), BN(X=0.3), B) by X-ray photoelectron, infrared absorption spectroscopies and internal stress measurements show that the c-BN/BN
X
/B/Si structure is useful as a mechanically stable passivation film.
Textural Pattern Observed in Iron and Vanadium Films Evaporated onto Copper (111) Surface
Authors: Ando Yoshinori , Bouzar Hamid , Dingley David J.
Published: February 2005

When iron and vanadium films vaccum-deposited onto copper (111) surface were thicker than 10 and 15 nm, respectively, regular textural patterns were observed in their images of transmission electron microscopy (TEM). The textural patterns were composed of numerous rectangles like laths and showed remarkable contrast at defocussing conditions of TEM, similar to Fresnel contrast. The size of each rectangle composing texture changed with the film thickness and substrate temperature. The most remarkable textural pattern was observed in three-layer film, V/Fe/Cu, and a similar pattern was also observed in the carbon replica taken from its film surface. Therefore, the textural pattern reflects the surface microtopography of each film.
A Theory of a Quartz Crystal Microbalance Based upon a Mason Equivalent Circuit
Authors: Nakamoto Takamichi , Moriizumi Toyosaka
Published: February 2005

The authors analyzed the behavior of a quartz crystal microbalance (QCM) in the experimental environments of air and liquid using a Mason equivalent circuit. It was found that the mass loading effect of QCM could be regarded as an inductance increase, and the analytical equation of the frequency shift, which is valid over the wide range of the thickness of a loading film, was derived. Utilizing this equation, the frequency shift can be predicted without solving the transcendental equation. Furthermore, it was found that various kinds of QCM problems, such as liquid loading and mass loading in liquid, could be solved using the same method because the acoustic load was expressed as a circuit component. Finally, the method to enhance mass loading sensitivity by depositing a thick film with low acoustic impedance over the quartz plate, was suggested.
Optical Detection of Moisture in Air and in Soil Using Dye-Doped Plastic Fibers
Authors: Muto Shinzo , Fukasawa Akihiko , Ogawa Takayuki , Morisawa Masayuki , Ito Hiroshi
Published: February 2005

The moisture-sensitive plastic fiber consists of poly-methylmethacrylate doped with phenol-red dye. The propagation loss of this fiber at around 530 nm increases with increasing water vapor in air, and hence it operates as an excellent humidity sensor with a fast response time. This fiber can also be used for optically detecting moisture equivalent in the soil.
Growth Temperature Dependence of µc-Si:H Films Sputtered with Hydrogen Gas
Authors: Sun Yong , Tonouchi Masayoshi , Miyasato Tatsuro
Published: February 2005

Hydrogenated microcrystalline Si films were deposited by RF sputtering with hydrogen gas in the temperature range of 100–400°C. X-ray diffraction, Raman spectroscopy, and FT/IR absorption measurements revealed that grain size and (110) orientation ratio increased, the growth rate and bonded hydrogen content decreased, and the Raman shift approached that of crystalline Si as the substrate temperature was raised. The temperature dependence of the characteristics suggested that hydrogen desorption together with Si elements from the growing surface and the growth temperature play an important role in determining the characteristics.
Observation of Three Subphases in Smectic C* of MHPOBC by Dielectric Measurements
Authors: Hiraoka Kazuyuki , Taguchi Ayumu , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

In the phase transition from the paraelectric smectic A to the antiferroelectric SmCA
* phase via the ferroelectric SmC* phase in MHPOBC, the existence of a subphase, SmCα
*, between SmA and the normal SmC* (SmCβ
*) was confirmed in addition to that of another subphase, SmCγ
*, between SmC* and SmCA
* by means of dielectric measurements. It was also confirmed that these subphases, SmCα
* and SmCγ
*, disappear in the same compound of lower optical purity as observed by DSC. The model structure of the SmCα
* phase is speculated on the basis of the dielectric measurements.
Optical Constants of a-SixC1-x:H Alloy Films Deposited by Tetrode RF Sputtering
Authors: Akimoto Makio , Akaida Yosinori , Gekka Yasuo
Published: February 2005

The optical constants of hydrogenated amorphous silicon-carbon alloy films have been determined using the pseudo-Brewster angle method. The a-SiC:H films were deposited by a tetrode RF sputtering technique applying the plasma decomposition of C3H8 and H2/Ar mixed gas. The partial pressure ratio of C3H8 to H2/Ar mixed gas, R
p, in the film deposition chamber was chosen as a variable factor for the film deposition. The dependences of the optical energy gap and refractive index of deposited films on R
p were investigated. It was concluded that the absorption edge of a-Si
x
C1-x
:H films is related to the carbon content (1-x) in the films, which is controlled by R
p.
High Hole Mobility in Modulation-Doped and Strain-Controlled p-Si0.5Ge0.5/Ge/Si1-Xs
GeXs
Heterostructures Fabricated Using Molecular Beam Epitaxy
Authors: Murakami Eiichi , Etoh Hiroyuki , Nakagawa Kiyokazu , Miyao Masanobu
Published: February 2005

New heterostructures of modulation-doped p-Si0.5Ge0.5/Ge/Si1-X
s
Ge
X
s
are fabricated using molecular beam epitaxy. The strain in the Ge channel layer can be precisely controlled by changing the composition of the Si1-X
s
Ge
X
s
buffer layer. As a result, a large energy discontinuity (0.22 eV) in the valence band is realized. This leads to the realization of a high hole mobility (4500 cm2/V ·s) at 77 K.
Relation between Pinning Potential and Critial Current Density of YBaCuO Superconducting Thin Films
Authors: Enpuku Keiji , Sako Ryuich , Kisu Takanobu , Yoshida Keiji
Published: February 2005

The relation between the pinning potential and the critical current density of YBaCuO thin films in weak magnetic fields is studied experimentally. The pinning potential U is obtained by comparing the current-voltage characteristics of the film with the flux-creep theory. The values U=25–120 meV are obtained for films with the critical current density j
c(T=0)=5.3×105–1.8×107 A/cm2. It is shown that the pinning potential increases with the increase of the critical current density. The obtained results can be qualitatively explained with the pinning model of isolated vortices.
Preparation of Single Crystals Containing the High-Tc (above 100 K) Phase of a Bi-Sr-Ca-Cu-O Superconductor
Authors: Suzuki Yasunao , Inoue Tetsuo , Hayashi Shigeyuki , Komatsu Hiroshi
Published: February 2005

High-T
c (T
c(zero)\fallingdotseq100 K) Bi-system single crystala were grown by annealing the bulk sample, which was prepared by slow cooling the melt of Bi:Sr:Ca:Cu=4:3:3:4, at 870°C for 100 h in air. It was found from the magnetization measurement (SQUID) that these crystals were mixtures of a high-T
c phase and low-T
c ones (possibly intergrowth).
Phase Transition and Crystal Structure of Ba2CuOx Oxide
Authors: Zhang Wei , Osamura Kozo
Published: February 2005

A phase transition in Ba2CuO
x
oxide from the orthorhombic to tetragonal phase has been identified. Two types of crystal structures of Ba2CuO
x
oxide have been determined by powder X-ray diffraction aided by Rietveld analysis using the program RIETAN. The orthorhombic phase exists at room temperature with the space group of Immm, a=0.40959(2), b=0.39047(2) and c=1.29420(8) nm. The tetragonal phase exists at high temperature above 1083 K with the space group of I4/mmm, a=b=0.39923(2), c=1.29686(8) nm.
Molecular Beam Epitaxy Study of Bi2Sr2CuOx Using NO2 as an Oxidizing Agent
Authors: Watanabe Shunji , Kawai Maki , Hanada Takashi
Published: February 2005

Molecular beam epitaxy (MBE) of Bi2Sr2CuO
x
films has been studied using NO2 as an oxidizing agent. The in situ RHEED and the XPS observations have shown that a two-dimensional layer of the Bi2Sr2CuO
x
phase is formed on a SrTiO3(100) surface even at 300°C under 2×10-7 Torr of NO2.
Operational Voltage Reduction in Total Internal Reflection Light Modulator Using Strontium Barium Niobate
Authors: Kim Sangkuk
Published: February 2005

The operational voltage reduction in total internal reflection light modulator was achieved using strontium barium niobate. The maximum modulation voltage can be reduced to less than 15 V with proximity coupled electric field. The frequency response exceeds 1 MHz without crystal size reduction.
A Phenomenological Theory of the Antiferroelectric Phase Transition in Smectic Liquid Crystals
Authors: Orihara Hiroshi , Ishibashi Yoshihiro
Published: February 2005

By applying the Landau theory, the appearance of the antiferroelectric phase in smectic liquid crystals and the double hysteresis loop are interpreted. Several types of phase sequences including the antiferroelectric, ferroelectric and/or ferrielectric phase are obtained phenomenologically. The D-E curves in the antiferroelectric phase are classified into three types depending on temperature and the coefficients of the fourth-order terms in the free energy.
Raman Scattering in Cuprate Oxides without Apical Oxygen Atoms
Authors: Uzumaki Takuya , Yamanaka Kazunori , Kamehara Nobuo , Niwa Koichi
Published: February 2005

Two-magnon Raman scattering, X-ray powder diffraction and oxygen content in (Ca0.86Sr0.14)CuO2 and T'-phase (Nd2-x
M
x
)CuO4 (M=Eu, Sm, La and Pr) were measured. We examined the relationship between two-magnon frequency and Cu-O bond length and found that the two-magnon frequency increased linearly with decreasing Cu-O bond length in the T'-phase. The two-magnon frequency of (Ca0.86Sr0.14)CuO2 is observed at a value consistent with a linear extrapolation of the relationship found for the T'-phase material. It suggests that the exchange interaction between electron spins in CuO2 sheets is closely related to the Cu-O bond length, and increases with decreasing Cu-O bond length.
Focal Conic Structures in Homogeneously Aligned Chiral Smectic C Liquid-Crystal Cells
Authors: Nakamura Katutoshi , Akahane Tadashi
Published: February 2005

The focal conic structure in homogeneously aligned chiral smectic C liquid-crystal cells is investigated by means of high-resolution X-ray analysis and polarizing microscopic observation. In the case of thick cells, ellipses of focal conics were observed to be densely distributed. Their sizes were widely distributed, but their shapes were all similar, and their long axes were all parallel to the rubbing direction. This type of cell showed almost the same X-ray diffraction pattern with the uniform chevron cell.
Enhanced Growth of Silicon Dioxide Films by Parallel-Resonant RF Plasmas
Authors: Kitagawa Akio , Takeuchi Masaki , Kasagi Masakatsu , Hayashi Masatoshi , Kouchi Yoshitaka , Suzuki Masakuni
Published: February 2005

Low-temperature plasma oxidation of silicon has been studied at 13.56 MHz. Localized plasma around the inductive coupling rf coil was generated in a parallel resonant condition of rf circuit. The growth rate of silicon dioxide films by the parallel-resonant rf plasma is dependent on oxygen pressure, rf power and dc substrate bias voltage. The growth rate of 1000 Å/h is attained at conditions of oxygen pressure 50 mTorr, substrate bias -60 V and rf power 130 W.
Increasing Phenomenon of Abnormal Absorption Current in Liquid Crystal Cells
Authors: Mada Hitoshi
Published: February 2005

An absorption current flowing in ordinal dielectrics monotonically decreases with time. However the current flowing in liquid crystals behaves more complexly. After switching on higher applied voltage, the current first decreases, and then tends to increase with a rather long relaxation time. This increasing phenomenon is explained by the electric double layer model. The phenomenon can be understood as an influence of discharge current according to the decrease of capacitance by reverse electric field due to the double layer. This relaxation time agrees with that of the ion drift, 6s, estimated in a previous paper.
Application of Optical Chaos to Temporal Pattern Search in a Nonlinear Optical Resonator
Authors: Davis Peter
Published: February 2005

An adaptive parametric control method has been proposed for using intrinsic dynamical chaos in a nonlinear system to search among a large number of multistable oscillation modes. We describe the application to a nonlinear optical device with digital and feature coding of oscillation patterns. Computer simulations indicate the control scheme is robust. We discuss the implications for adaptive devices and optical computing.
Neighborhood Operations of Optical Parallel Processor
Authors: Hashimoto Masashi , Kitayama Ken-ichi , Mukohzaka Naohisa
Published: February 2005

An optical parallel processor based upon polarization encoding that performs neighborhood operations is implemented by newly introducing an optical shifter. The experimental results of edge extraction are demonstrated.
Joint Transform Correlator Using a Phase Only Spatial Light Modulator
Authors: Barnes Thomas Heinrich , Matsuda Kiyofumi , Eiju Tomoaki , Matsumoto Kenji , Johnson Francis
Published: February 2005

A Joint Transform Optical Correlator is described which uses a phase only spatial light modulator for input of the Joint Transform plane information into the second stage of the correlator. This, combined with suitable apodizing of the Joint Transform plane intensity distribution, brings several advantages including high optical efficiency, good signal-to-noise ratio, and the ability to correct system aberrations.
Design and Fabrication of Highly Efficient Fan-Out Elements
Authors: Herzig H. P. , Prongué D. , Dändliker R.
Published: February 2005

This paper reports the calculation and fabrication of periodic phase structures for fan-out elements with a theoretical conversion efficiency close to 100% and perfect uniformity. We have measured an efficiency of 92% for a smooth kinoform structure fabricated in photoresist by laser beam writing lithography.
Optical Implementation of Semantic Networks Based on Association
Authors: Hayasaki Yoshio , Kasama Nobuyuki , Yatagai Toyohiko , Mori Masahiko , Ishihara Satoshi , Yajima Hiroyoshi
Published: February 2005

An optical system combining a semantic network technique and an associative network architecture is presented. In the optical implementation of the associative system, an MSLM is used to store an optimum weight matrix. The optimum weight matrix is calculated by a dynamic learning rule.
Optoelectronic Implementation of Bipolar Analog Neural Network Using Shadow Casting
Authors: Zhang Wei , Tanida Jun , Itoh Kazuyoshi , Ichioka Yoshiki
Published: February 2005

Based on the optical shadow casting technique, we propose an optoelectronic implementation of neural network with bipolar analog neurons and interconnection weights. Experimental results of an associative memory based on the Hopfield model using the proposed method are also described.
Holographic On-Line Learning Machine for Multicategory Classification
Authors: Paek Eung Gi , Patel John R. Wullert II
Published: February 2005

A holographic on-line learning machine that is capable of multicategory classification is described. The system exactly implements the single-layer perceptron algorithm in a fully parallel and analog fashion. The performance of the adaptive network is successfully tested for up to 24 characters with different scale and rotation. Also, a compact and robust version of the holographic learning machine is proposed.
Consideration on Mobility Lowering Phenomenon in PolySi Films Using Tunneling Barrier Height Images
Authors: Sagara Kazuhiko , Hosaka Sumio
Published: February 2005

Polycrystalline silicon films were deposited on SiO2, and arsenic ions were implanted into these films. The Hall and resistivity measurements show that the mobility lowering effect and the activity lowering effect dominate the electrical properties of the films. Tunneling barrier height images also suggest carrier trapping at grain boundaries in lightly doped cases, indicating the possibility of arsenic segregation. These results indicate that the mechanism of the mobility lowering effect is mainly governed by the carrier trapping at grain boundaries.
Atomic Layer Epitaxy of GaAs Using GaCl3 and AsH3
Authors: Jin Yoshito , Kobayashi Ryuji , Fujii Kunihiro , Hasegawa Fumio
Published: February 2005

It was demonstrated that the atomic layer epitaxy (ALE) of GaAs could be performed by using GaCl3/H2 and AsH3/H2. The GaCl3 is a powder at room temperature and can be supplied from outside the reactor, and is essentially carbon free. The ALE growth temperature was from 200°C to 500°C. The growth temperature of 200°C is the lowest ever reported in GaAs ALE. The fact that the ALE was performed at 200°C indicates that Ga was supplied as GaCl3, suggesting the possibility of AlGaAs ALE using AlCl3, GaCl3 and AsH3.
Observation of Laser-Induced Melting of Silicon Film Followed by Amorphization
Authors: Sameshima Toshiyuki , Hara Masaki , Sano Naoki , Usui Setsuo
Published: February 2005

Transient conductance measurements were used to study laser-induced amorphization of polycrystalline silicon (poly-Si) film. A 20 nm-thick phosphorus-doped poly-Si film fabricated on a quartz substrate was melted by irradiation with a 30 ns-pulsed XeCl excimer laser. When the melt duration exceeded 70 ns, the silcon film was completely amorphized through rapid solidification. Formation of the amorphous thin film may be brought about by homogeneous solidification without crystalline nucleation.
Photoluminescence of a-Si:H Films Prepared by Catalytic Chemical Vapor Deposition Method
Authors: Yamaguchi Masaaki , Matsumura Hideki , Morigaki Kazuo
Published: February 2005

Photoluminescence in a-Si:H films fabricated using the catalytic chemical vapor deposition method has been measured at 7–300 K. Its property is very similar to that of a-Si:H films produced by the glow discharge decomposition of SiH4gas. Study of the photoluminescence measurements reveals that high-quality films are obtained by the catalytic vapor deposition method.
Crystal Structure of a New Copper-Oxide Compound Pb2Sr2(Nd1-yCey)2Cu3O10+δ with PbO-CuOδ-PbO Unit
Authors: Mochiku Takashi , Osawa Makoto , Asano Hajime
Published: February 2005

We have discovered a new copper-oxide compound Pb2Sr2(Nd1-y
Ce
y
)2Cu3O10+δ with PbO-CuOδ-PbO unit. The crystal structure was determined by Rietveld analysis of X-ray powder diffraction data. The structure can be derived by stacking Pb2Sr2LnCu3O8- and Nd2CuO4-type slabs alternately along the c-axis; they are joined by conductive CuO2 sheets. The compound does not exhibit superconductivity down to 4.2 K.
Growth and Characterization of Homogeneous YBa2Cu3O7-δ Powders Prepared by a Freeze-Drying Method
Authors: Kimura Yoshitaka , Ito Toshimichi , Yoshikawa Hiroaki , Tachiwaki Tokumatsu , Hiraki Akio
Published: February 2005

Homogeneous superconducting powders of YBa2Cu3O7-δ have been successfully prepared from a carbonate solution by means of a freeze-drying method. Sintered powders at 930°C were characterized by 100% volume fraction of the superconducting phase in measurements of field-cooled magnetization at 4.5 K in low fields (\lesssim2 Oe) using a SQUID magnetometer. It turned out that large plate-shaped grains (∼2×5×20 µm3) grew when the powders were heated in a short period (\gtrsim6 hours) and that the packing density was considerably high even without any pressing process.
EXAFS Study on the Local Structure of Cu in Bi-Pb-Sr-Ca-Cu-O Systems
Authors: Uehara Yasushi , Kamijo Nagao , Kageyama Hiroyuki , Wakata Mitsunobu
Published: February 2005

We have conducted an EXAFS study of two kinds of Pb-added Bi-Sr-Ca-Cu-O superconductors with different compositions having different T
c. Copper in the specimen, which mainly consists of the high T
c phase (Bi2Sr2Ca2Cu3O
y
), has nearly the same coordination number as that of the specimen which has a nearly equal amount of the high T
c phase and the low T
c phase (Bi2Sr2CaCu2O
y
). The former specimen showed a smaller Debye-Waller parameter of in-plane Cu-O bonds than did the latter specimen, both at room temperature and at 77 K.
Crystal Structure of a New Pb-Based Copper Oxide Pb2SrLaCu2O6+δ
Authors: Nakahigashi Kiyotaka , Sasakura Hiroyuki , Minamigawa Shinnosuke , Kogachi Mineo
Published: February 2005

The crystal structure of a new Pb-based copper oxide superconductor Pb2SrLaCu2O6+δ (T
c=33 K) has been analyzed by the Rietveld method on the basis of the X-ray powder diffraction data. The material has a single CuO2 sheet and orthorhombic symmetry with a probable space group Cmmm. Its lattice parameters are a=5.3048(9) Å, b=5.4108(3) Å and c=12.689(1) Å. Of the two Cu atoms in the unit, one has twofold coordination while the other has sixfold octahedral coordination with the apexes elongated along the c-axis.
Metalorganic Molecular Beam Epitaxial Growth of ZnSe and ZnS on GaAs Substrates Pretreated with (NH4)2Sx Solution
Authors: Wu Yi-hong , Toyoda Takashi , Kawakami Yoichi , Fujita Shizuo , Fujita Shigeo
Published: February 2005

We tried to prepare ZnSe and ZnS epilayers on GaAs(100) substrates pretreated with a (NH4)2S
x
solution. As a result, it was found that it is possible to grow ZnSe with layer-by-layer or two-dimensional growth from an initial stage of growth under appropriate growth conditions. The surface morphologies of ZnSe and ZnS epilayers are better than those grown on GaAs substrates pretreated in a conventional manner in which GaAs is heated to remove the surface oxidized layer. Furthermore, it was also found that the optical properties of thin ZnSe and ZnS epilayers can greatly be improved through pretreatment of the substrates with (NH4)2S
x
solution.
Epitaxial Growth of EuBa2Cu3O7-y Films on YAlO3 Single Crystals
Authors: Asano Hidefumi , Kubo Shugo , Michikami Osamu , Satoh Makoto , Konaka Tsuneo
Published: February 2005

Epitaxial growth of 1-2-3 superconductor films is reported on a new substrate material that possesses desirable dielectric properties. Magnetron-sputtered EuBa2Cu3O7-y
films on YAlO3(001) show excellent properties with a T
c of 91 K. Films are epitaxially grown with the c-axis oriented normal to the surface, and the a- and b-axes ordered in the plane. The high-frequency (50 GHz) surface resistance of a film is 2 mΩ at 30 K. The dielectric constant of YAlO3 is 16. The dielectric loss tangent at 10 GHz is as low as 7.3×10-5 at 300 K and 2×10-6 at 40 K. YAlO3-based films have considerable potential for high-frequency application.
Rapid Tracking of Resonance and Antiresonance of a Piezoelectric Resonator
Authors: Hayashi Shigeo , Kuwabara Yuji , Sasaki Yukihiko
Published: February 2005

Improvements have been made on the tracking of resonance and antiresonance in a piezoelectric resonator reported previously by the authors. For a disk PZT resonator, it was possible to achieve phaselock in a fundamental mode (f
r=100.3 kHz, f
a=118.6 kHz) if integrator time constant τ\gtrsim10 ms, whereas locking onto the next higher mode (f
r=255.7 kHz, f
a=262.3 kHz) occurred if τ\gtrsim44 ms. For the fundamental mode, the lock-acquisition time T could be described by T\congA|f
0-f
r,a|
m
, where m≈0.35 and A≈4 ms, f
0 is an initial frequency in kHz, and f
r,a=f
r or f
a in kHz.
Suppression of Rapid Beam Loss at Low Energy by RF Excitation of Betatron Oscillation
Authors: Takada Hiroshi , Tsutsui Yasumitsu , Tomimasu Takio
Published: February 2005

Rapid beam loss was observed below the injection energy of 100 MeV in the NIJI-I compact electron storage ring. RF excitation of vertical betatron oscillation was tried for stabilization of the stored beam. The instability was successfully suppressed by this method. It was also found that the application of this method could enlarge the beam size incoherently and was particularly effective for high-current beam storage at low-energy injection, resulting in cost reduction of the compact ring system.
Low-Temperature Synthesis of Diamond Films Using Magneto-Microwave Plasma CVD
Authors: Wei Jin , Kawarada Hiroshi , Suzuki Jun-ichi , Hiraki Akio
Published: February 2005

At a low temperature of 500°C, we have formed diamond films on Al substrates at 0.1 Torr using a magneto-microwave plasma CVD system. Since diamond can be formed at the low pressure of 0.1 Torr, the important parameters for diamond formation such as the plasma density during the diamond deposition can be measured and is found to be the highest (2.1×1011 cm-3) at ECR condition. Above 1×1011 cm-3, using a (CH4+CO2)/H2 mixture, which is a suitable reaction gas for low-temperature diamond formation, high-quality diamond films have been obtained at temperatures as low as 500°C and at low pressure (0.1 Torr) on Al.
Variable-Energy Positron Studies of Vacancy-Type Defects in TiN Films on Si
Authors: Wei Long , Dosho Chisei , Cho Yang-koo , Tanigawa Shoichiro , Hinode Kenji
Published: February 2005

A variable-energy (0–30 keV) positron beam has been used as a nondestructive probe for titanium nitride (TiN) films with a thickness of 800 nm deposited on Si substrates by a reactive sputter deposition in a DC-planar-magnetron-type apparatus. Doppler broadening profiles of positron annihilation radiation are measured as a function of incident positron energy. It is found that the density of titanium vacancies depends on the concentration of titanium in the TiN film. Titanium vacancies are abundant in the titanium-deficient TiN film. The precipitation of metallic titanium is not involved in the specimens.
Influence of Synchrobetatron Resonance on Low-Energy Injection Beam with a Compact Storage Ring
Authors: Takada Hiroshi , Tsutsui Yasumitsu , Tomimasu Takio
Published: February 2005

The effects of synchrobetatron resonance on a low-energy beam were studied using a compact storage ring. The beam profile and lifetime were measured on and off the resonance line. Although the first and second resonances were dangerous, the beam lifetime became long on the third and fourth resonances due to the vertical beam size enlargement. Through DC ion clearing, it was also found that the betatron tune shift and spread, which are caused by trapped ions, were reduced with a decrease in beam energy, contrary to expectations. These results indicate that the operating point for injection is not particularly limited in narrow regions. Moreover, the possibility of high current beam storage at low energy is suggested by making full use of the third and fourth resonances.
Effect of Plasma Temperature on MPD Arcjet Cathode Surface Current Density Distribution
Authors: Sheshadri T. S.
Published: February 2005

The effect of plasma temperature on the radial current density distribution at the cathode longitudinal surface of an MPD arcjet is theoretically investigated by solving the electromagnetic equations for a typical geometry. It is found that the magnitude of the current density increases strongly with increasing temperature and beyond a certain temperature, a current density concentration develops at the cathode upstream edge. This temperature is species dependent and has values of 10,000 K and 8,500 K for argon and hydrogen respectively.
Photo-CVD Direct Patterning of Silicon Oxide Films by Optical Projection
Authors: Suzuki Yoshihiko , Shin-ogi Masataka
Published: February 2005

Patterned silicon oxide films from gaseous hexamethyldisilazane (HMDS) were deposited by a direct patterning method of photoinduced chemical vapor deposition (photo-CVD) using an argon-fluoride (ArF) excimer laser and a photomask. From Auger electron spectroscopy (AES) analysis, these films are seen to have much oxygen and carbon contamination. The growth mechanism was discussed by considering dissociation, adsorption and chemical reaction.
Charge Transfer as an Alternative to Metastability of Defects in Semi-Insulating GaAs?
Authors: Benchiguer T. , Christoffel E. , Goltzené A. , Mari B. , Meyer B. , Schwab C.
Published: February 2005

We have compared the variations of different paramagnetic signals, including that of the AsGa -related antisite, as revealed during 1.2 eV light exposures at 4.2 K, with those observed during a subsequent warming up in several semi-insulating GaAs samples. In addition to a confirmation of the sequence of acceptor levels regarding their energy depth, these experiments suggest a possibility of a mere charge transfer mechanism instead of a metastability for the photoquenchable AsGa-related deep donors.
Simultaneous Observation of Atomically Resolved AFM/STM Images of a Graphite Surface
Authors: Sugawara Yasuhiro , Ishizaka Tatsuya , Morita Seizo , Imai Syozo , Mikoshiba Nobuo
Published: February 2005

We constructed an AFM/STM system with a conductive lever. We applied this system to the observation of a graphite surface in air. As a result, for the first time, atomically resolved AFM and STM images were obtained simultaneously, and it was found that the lattice pattern appearing in the AFM image was different from that in the STM image. In both AFM and STM images, distortion of lattice periodicity due to frictional effect was observed.
The Correlation between Photocreation of Dangling Bonds and Si-H Bond Clusters in a-Si:H
Authors: Morigaki Kazuo
Published: February 2005

The correlation between photocreation of dangling bonds and clustered Si-H bonds in a-Si:H is discussed in terms of a model which takes into account the self-trapping of holes in a weak bond adjacent to a Si-H bond.
A Trial Construction of an Ultrasonic Motor with Fluid Coupling
Authors: Nakamura Kentaro , Ito Takaaki , Kurosawa Minoru , Ueha Sadayuki
Published: February 2005

A fluid coupling type ultrasonic motor, which employs fluid between the rotor and the stator, is proposed and constructed for trial. This ultrasonic motor does not use frictional force and is free from the difficulties of contact, such as abrasion and surface roughness. Though the precise mechanism of the motor is not clear, the maximum revolution of 50 rpm is marked.
Localized Orientation Control in BiSrCaCuO Superconducting Film
Authors: Nagai Yasuhiro , Tsuru Koji
Published: February 2005

This letter reports on localized orientation control in BiSrCaCuO superconducting films. Uniformly oriented crystals, of which the c-axis exists in-plane, were grown on a MgO (110) plane by annealing them in contact with a MgO (100) plane. Thus, stripe patterns including oblique tapers in stripe edges were fabricated on MgO (100) crystals to produce locally appearing (110) planes. By annealing them in contact with a MgO (100) plane, the uniformly oriented crystals were confirmed to grow around oblique tapers in stripe edges fabricated on MgO (100) crystals.
Preparation of Superconducting 1201 Phase in the (Pb1-yCuy)Sr2-xLaxCuOz System
Authors: Sasakura Hiroyuki , Nakahigashi Kiyotaka , Hirose Akinori , Teraoka Hiroshi , Minamigawa Shinnosuke , Inada Katsuhiko , Noguchi Satoru , Okuda Kiichi
Published: February 2005

An almost-single-1201-phase sample has been synthesized in the (Pb1-y
Cu
y
)Sr2-x
La
x
CuO
z
system. The sample showed the superconducting transition with the onset temperature of about 36.5 K and a zero resistivity temperature of about 31.5 K. These values were about 7 K higher than those reported by Adachi et al. The X-ray powder diffraction study showed that the almost-single phase was attained at the nominal composition of x=0.9 and y=0.5, and the crystal structure had a tetragonal symmetry with a=0.3769 nm and c=0.8697 nm.
Influence of the Flux Creep on the Critical Current Density in Bi2Sr2Ca2Cu3Ox and Y(Ho)Ba2Cu3Oy Superconductors
Authors: Kumakura Hiroaki , Togano Kazumasa , Yanagisawa Eiji , Kase Jun-ichiro , Maeda Hiroshi
Published: February 2005

Intragrain J
c values of the textured Bi- and Y-based oxides were obtained at 4.2 K–77 K by the D.C. magnetization measurements with various sweep rates of the magnetic field. The J
c's at 4.2 K were comparable for both oxides. However, with increasing temperature, the J
c of the Bi-based oxide became much more sensitive to the electric field criterion E
c related to the sweep rate of the magnetic field than that of the Y-based oxide. As a result, J
c at 77 K of the Bi-based oxide was significantly decreased in magnetic fields for small E
c. The dependence of J
c on E
c for both oxides can be well understood using the flux creep model.
Light Modulation by Applying High Electric Fields in Double-Insulated ZnS and ZnSe Polycrystalline Films
Authors: Hirabayashi Katsuhiko , Ono Ken'ich
Published: February 2005

Absorption-edge shifts produced by applying electric fields (Franz-Keldysh) in ZnS and ZnSe polycrystalline films have been studied for investigating their application to spatial light modulators. The ZnS and ZnSe polycrystalline films are sandwiched between the insulating layers so that high electric fields of up to about 106 V/cm can be applied to the films. As a result, the adsorption edge is shifted by about 3 nm toward longer wavelength and a light modulation degree of 45% is obtained.
High Field Characteristics of Ultrathin Film of Polyacetylene Derivative Studied with Surface Potential Measurement by Corona Discharge
Authors: Yoshino Katsumi , Yamamoto Yoshihiro , Kyokane Jun
Published: February 2005

Surface potential of corona-charged ultrathin films of a polyacetylene derivative, poly(1-trimethylsilyl-1-propyne), increases with increasing corona voltage, tending to saturate at some limited value V
th. From this V
th value, the breakdown strength is evaluated to be 200 MV/cm, 50 MV/cm and 1.5 MV/cm for films with a 40 Å, 200 Å and 1 µm thickness, respectively. Resistivity of the sample was also evaluated from the decaying characteristics of the surface potential.
Photon Stimulated Desorption of CO from Si Single Crystal
Authors: Murashita Toru , Kaneko Takashi , Yoshihara Hideo , Kobayashi Masanori
Published: February 2005

Photon-stimulated desorption (PSD) of CO from Si single crystal is studied carefully by the throughput method. The photodesorption yield of Si single crystal is lower than that of OFHC copper. To investigate the effect of impurities in Si, stable isotope 13C is chosen as an impurity. 13CO is hardly detected in the outgas due to PSD from 13C-implanted, Si single crystal. It is concluded that carbon in Si single crystal is not desorbed in the PSD process.
Domain Structures of As-Adsorbed Si(100) Surface and GaAs Overlayer
Authors: Uneta Makoto , Watanabe Yoshio , Fukuda Yukio , Ohmachi Yoshiro
Published: February 2005

The surface domain structures of As-adsorbed Si(100) substrates and of subsequently overgrown GaAs films are observed by reflection high energy electron diffraction. Single-domain Si(100)2×1 is obtained by using samples cut at 4° from the (100) crystal axis towards (011). Even at a low substrate temperature of 200°C, As adsorption causes the RHEED pattern to rotate from 2×1 to 1×2, indicating formation of As-As dimers on the Si(100). This surface reconstruction does not change after thermal annealing at 650°C. Furthermore, GaAs layers are grown on two types of As-adsorbed Si(100) substrates. One is subjected to the subsequent 650°C annealing and the other has no subsequent annealing. Upon two-step growth of GaAs layers at 400°C and 630°C on these As-adsorbed Si substrates, both final GaAs surfaces reveal the 4×2 reconstruction, independent of the subsequent annealing of As-adsorbed Si substrates. Previous observation that the domain structure of GaAs on As-adsorbed Si depends on the As-adsorption temperature, is assigned to the presence of the double-domain structure of the Si(100) surface.
SiGe Passivation for Si MBE Regrowth
Authors: Niino Taeko , Tatsumi Toru
Published: February 2005

One of the problems in Si molecular beam epitaxy regrowth for device application is that the cleaning conducted prior to regrowth results in unintentional etching of the Si layer grown in the preceding process. In this study, a SiGe epitaxial layer was successfully applied as a protective coating before RCA cleaning, and a one-order-lower defect density was obtained using the SiGe protective layer without any etching of the Si underlayer. The SiGe layer was completely removed by RCA solution and no Ge was detected in the regrowth layer by Auger electron spectroscopy.
Measurement of Negative Ions by Photodetachment with YAG Laser in Discharge Plasmas
Authors: Amemiya Hiroshi , Suzuki Takanori
Published: February 2005

The photodetachment response of neagative ions has been investigated with YAG lasers using a hollow cathode discharge in oxygen. The current of electrons released by the laser has been measured as a function of the discharge current and the pressure. The diagnostic method is formulated in such a manner that the densities of atomic and molecular negative ions are determined simultaneously from the response of photodetached electrons to the fundamental and second harmonic radiation of YAG laser. The sum of the densities compares well with the total negative ion density obtained by the probe method.
GaAs PN Diodes with Heavily Carbon-Doped P-Type GaAs Grown by MOMBE
Authors: Nozaki Shinji , Miyake Ryuji , Yamada Takumi , Konagai Makoto , Takahashi Kiyoshi
Published: February 2005

GaAs pn diodes with heavily carbon-doped p-type GaAs grown by MOMBE were fabricated. The I-V and C-V characteristics were not significantly affected by the hole concentration of the p-GaAs although a lattice mismatch at the junction generates misfit dislocations. A good I-V characteristic with the ideality factor of 1.3 was obtained even for the carbon-doped GaAs with a hole concentration of as high as 5×1020 cm-3. The electron diffusion lengths in the carbon-doped GaAs were determined to be 1.0, 0.45 and 0.25 µm for hole concentrations of 2×1018, 1×1020 and 5×1020 cm-3, respectively, by EBIC and spectral response measurements.
Cracking Yield Dependence of InP Growth by Chemical Beam Epitaxy
Authors: Uchida Toshi K. , Uchida Takashi , Yokouchi Noriyuki , Mise Kazuaki , Koyama Fumio , Iga Kenichi
Published: February 2005

A high P2-yield cracking cell was newly developed for chemical beam epitaxy. Dramatic improvements in crystal quality were obtained in comparison to a lesser-yield cell. The use of tantalum baffles in a PBN-made cell significantly increased the P2 yield when comparing it to a cell using PBN baffles. The growth mechanism of InP differed from cells with different P2 yields. For the same PH3 and TMI flow rates, higher growth rates and narrower photoluminescence linewidths were obtained with a higher P2 yield cell. Silicon and beryllium doping incorporation mechanisms were also found to be different with these cells.
Pyrolysis of Trimethylgallium on GaAs Surfaces Observed by Pulse Surface Reaction Rate Analysis
Authors: Hoshino Masataka
Published: February 2005

A pulse surface reaction rate analysis (PSRA) was used for determining the rate constants of CH4 formation from TMGa on a GaAs surface. I observed three different rate constants at the same temperature. I hypothesized that the three rate constants are the rate constants for releasing the first, second, and third methyl groups in TMGa on the GaAs surface. The largest rate constant of the three does not satisfied the Arrhenius equation because the rate is as large as the measurement limits. However, the rate constants of the second and third large rate constants, k
2 and k
3, are formulated.
Low-Temperature Preparation of Doped Hydrogenated Amorphous Silicon Films by AC-Biased Microwave ECR Plasma CVD Method
Authors: Kitagawa Masatoshi , Hirao Takashi
Published: February 2005

Phospborus and boron doped bydrogenated amorphous silicon films were deposited by microwave electron-cyclotron-resonance (ECR) plasma CVD with an AC (20 kHz) substrate bias. Electrical properties of the films have been investigated. The dark conductivity gradually increased with the increase of AC substrate bias power. Above the 50 W bias power, the conductivities of about 10-6 ( Ω·cm)-1 and about 10-7 ( Ω·cm)-1 were obtained for both P-doped and B-doped films respectively, under the low substrate temperature below 50°C. These doped films were applied to the fabrication of the a-Si:H junction diode with a structure of glass/Cr/pin/Al. A diode quality factor of about 2.2 was evaluated and a ratio of forward current to reverse current of more than 104 was obtained at 1.5 V.
Fracture Toughness of YBaCuO Prepared by MPMG Process
Authors: Fujimoto Hiroyuki , Murakami Masato , Oyama Terutsugu , Shiohara Yuh , Koshizuka Naoki , Tanaka Shoji
Published: February 2005

The fracture toughness of melt-powder-melt-growth(MPMG)-processed YBaCuO samples was measured and the beneficial effect of the dispersed 211 particles in the 123 superconducting phase on toughening the material was confirmed. Preferred fracture planes were (100), (010) and (001) planes, and the fracture toughness of the (001) plane was lower than that of the (100) and (010) planes.
Crystal Structure of New Metallic Compound Cu6O8·InCl
Authors: Hayakawa Hiroshi , Akiba Etsuo , Yazawa Ichiro , Ihara Hideo , Ono Shuitiro
Published: February 2005

Crystal structure analysis of a new metallic compound, Cu6O8·InCl, has been carried out using the X-ray powder pattern-fitting method (Rietveld method) together with thermal analysis. This compound has a face-centered cubic structure analogous to Ag7O8(NO3) with a space group of Fm 3̄m and a unit cell dimension of a=9.166 Å (R
wp=2.65%). This compound decomposed at 600°C to CuO and In2Cu2O5.
Properties of Tl2Ba2Ca2Cu3Ox Thin Films with a Critical Temperature of 122 K Prepared by Excimer Laser Ablation
Authors: Nabatame Toshihide , Saito Yukio , Aihara Katsuzo , Kamo Tomoichi , Matsuda Shin-Pei
Published: February 2005

Superconducting thin films with a single Tl2Ba2Ca2Cu3O
x
(2223) phase were fabricated on MgO(100) substrates using excimer laser ablation and post annealing. The films had a highly c-axis-oriented structure and showed zero resistance at 122 K. Diamagnetism also appeared at 122 K and a 95% transition was achieved at 110 K. The critical current density of the film at 77 K was 1.5×105 A/cm2 at 0 T.
Highly-Strained InxGa1-xAs/GaAs Multiple Quantum Wells for Electroabsorption Modulation
Authors: Niki Shigeru , Cheng An-nien , Chang Jessica C. P. , Chang William S. C. , Wieder Harry H.
Published: February 2005

The properties of strained In
x
Ga1-x
As/GaAs multiple quantum wells with indium concentrations of up to 0.28 were investigated experimentally for surface-normal electroabsorption modulator applications in the 0.9 to 1.1 µm wavelength range. A 0.5 µm-thick alloy buffer (In
y
Ga1-y
As or In
y
Al1-y
As) was employed in order to relax the in-plane lattice constant of the epitaxial layers from that of GaAs, with two sets of QW layers sharing the strain in opposite directions (oscillating compressive/tensile strain). Distinct exciton peaks and clear quantum confined Stark effect with the maximum Δα=5900 (cm-1) were obtained from such structures at λ=1.05–1.09 µm, indicating good material quality.
Real-Time Optical Holography Using a Spatial Light Modulator
Authors: Poon Ting-Chung , Duncan Bradley D. , Wu Ming Hsien , Shinoda K. , Suzuki Y.
Published: February 2005

A real-time technique for recording and reconstructing optical holograms is proposed. Holographic recording is accomplished by scanning an object with two superposed light beams of different temporal frequencies. For reconstruction, the scanned information is transferred to an electron beam addressed spatial light modulator for coherent processing and optically read out to reconstruct an image of the scanned object.
Effects of Proton Implantation on Amorphous SiO2 Predamaged by Si Implantation
Authors: Fujita Tetsuo , Fukui Minoru , Okada Syunji , Iwayama-Shimizu Tsutomu , Itoh Noriaki
Published: February 2005

The effects of H implantation on amorphous SiO2 preimplanted with Si have been studied through electron paramagnetic resonance (EPR). It is shown that both the width and intensity of the EPR spectra of the E1
′ centres generated by Si implantation increase upon H implantation, in contrast to the results for Ar and succeeding H implantation. The difference is ascribed to the difference in the effective cross section of annihilation under proton implantation of the E1
′ centres in Si- and Ar-implanted SiO2. The result supports the previously propsed model in which the combination of Si and interstitial O reduces the annihilation of the E1
′ centres.
Photo-CVD of Al2O3 Thin Films
Authors: Saraie Junji , Ngan Sin-fat
Published: February 2005

Al2O3 thin films have been prepared by photo-CVD under oxygen atmosphere for the first time using aluminum-tri-isopropoxide as a source material. The light source was a low-pressure Hg lamp. Without UV irradiation the deposition rate had a maximum at a particular oxygen-flow rate, which suggests the Langmuir-Hinshelwood surface-reaction mechanism. With UV irradiation, the deposition rate increased largely at a substrate temperature of less than 300°C. The activation energy of deposition reaction was as small as 1.5 kcal/mol. It was confirmed that the 185-nm light played an important role in the photodeposition. The dielectric dissipation factor ( tan
δ) decreased in the samples prepared by photo-CVD, especially at a low substrate temperature of less than 300°C; that is, the film quality was improved by photo-CVD.
Surface Hydrogen Desorption as a Rate-Limiting Process in Silane Gas-Source Molecular Beam Epitaxy
Authors: Hirose Fumihiko , Suemitsu Maki , Miyamoto Nobuo
Published: February 2005

Surface chemical processes of the silane gas-source molecular beam epitaxy were investigated for Si(100) and Si(111) surfaces by comparing the growth rate with the surface hydrogen coverage during epitaxy. The surface hydrogen coverage was obtained through a thermal desorption measurement just after a quenching of the epitaxy. It was found that the hydrogen desorption process is the major rate-limiting process both on Si(100) and Si(111) surfaces below 600°C.
Surface Composition and Electrochemical Properties of High-Dose Carbon-Implanted Iron
Authors: Fujihana Takanobu , Takahashi Katsuo , Sekiguchi Atsushi , Iwaki Masaya
Published: February 2005

The effect of high-dose C+-implantation on the anodic dissolution properties of iron was studied by multisweep cyclic voltammetry in an acetate buffer solution of pH 5.0. Implantation of 12C+ was performed with a dose of 1×1018 ions/cm2 at an energy of 100 keV. The XPS was used to analyze the depth profile and chemical bonding state of carbon in the surface layers of C+-implanted iron. High-dose C+-implantation was extremely effective in suppression the anodic dissolution of iron in the solution. The dissolution process is discussed from the depth profiles measured before and after electrochemical treatments.
Optogalvanic Measurement of Negative Ions in Plasma by Semiconductor Lasers
Authors: Amemiya Hiroshi , Suzuki Takanori , Shigueoka Yoshyuki
Published: February 2005

The optical response of plasmas has been measured by irradiating semiconductor lasers to hollow-cathode-type discharges in oxygen. The signal generated by the photodetachment from negative ions has been measured for some discharge condition of currents and pressures. The diagnostic method for obtaining densities of atomic and molecular negative ions in an electronegative gas discharge is described.
Location Measurement of High-Energy Electrons in Nagoya Bumpy Torus Using an Impurity Pellet
Authors: Morita Shigeru , Kawatoh Eizoh , Hosokawa Minoru , Takahashi Chihiro
Published: February 2005

An impurity pellet of 0.5 mmφ aluminum sphere is injected into Nagoya Bumpy Torus (NBT-1M) and radial locations of high-energy electrons, so called hot-electron ring, are measured successfully with observations of synchrotron radiation and visible light emission from the pellet which is not ablated. The result shows that the ring thickness is 4–6 cm and the spatial location of the hot electron ring is consistent with a radial position of 2nd-harmonic resonance layer of 18 GHz electron cyclotron frequency varying with an applied magnetic field. It is demonstrated that the present method is useful for diagnostics of the high-energy electrons.