bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Diagrams in the Solid Solution Nd–Ba–Cu–O System and NdBa2Cu3O7-δ Single Crystals Growth by the Traveling-Solvent Floating-Zone Method
Authors: Kuroda Kiyoshi , Itoi Kazuhisa , Okano Jun-ichi , Segawa Souichi , Abe Keita , Choi In-Hwan , Hiromi Unoki Hiromi Unoki , Naoki Koshizuka Naoki Koshizuka
Published: October 2002

We have investigated the pseudo-binary phase diagrams between NdBa2Cu3O7-δ (Nd123) and several Ba–Cu–O compositions in air and reduced oxygen atmosphere by DTA, quenching, and X-ray powder diffraction measurements. We found that in air the wider liquidus line exists in the 60–90% concentration of (1/13) Ba3Cu10O13 [40–10% (1/6) Nd123] at 940–1090° C. Under 0.1% O2 in Ar, the liquidus line on the same pseudo-binary line shifts to the 65–92.5% concentration of (1/13) Ba3Cu10O13 [35–7.5% (1/6) Nd123] at 850–1000° C. Furthermore, we tried to grow single crystals of Nd123 based on these phase diagrams by traveling-solvent floating-zone method under 0.1% O2 in Ar. We could get a single crystal rod having the composition of Nd1.02Ba1.98Cu3O7-δ and the T
C∼93 K in all through the length of the crystal rod.
Direct Overwrite Magneto-Optical Disks with Double Mask Type Magnetically Induced Super Resolution
Authors: Fujii Yoshio , Takashi Tokunaga Takashi Tokunaga , Koichi Yamada Koichi Yamada
Published: October 2002

Light intensity modulation direct overwrite (LIMDOW) magneto-optical disks with a double mask type rear aperture detection (RAD) magnetically induced super resolution (MSR) function were investigated in comparison with LIMDOW disks with a front aperture detection (FAD) MSR function. Crosstalk, cross-write and carrier-to-noise ratio at various recording densities were evaluated and a track pitch of 0.6 µ m and mark length of 0.4 µ m which corresponds to an areal density of 3.6 Gbit/inch2 in (1, 7) run length limited pulse width modulation was a potential target for a LIMDOW-FAD disk provided that the crosstalk free condition of the L/G recording scheme was satisfied. On the other hand, LIMDOW-RAD disks showed very low crosstalk in a specified readout field range. The high resolution power of double mask RAD also proved to be effective in LIMDOW-RAD disks and it resulted in a wider power margin and higher carrier level than those in FAD-MSR. LIMDOW-RAD disks are more suitable for high density recording, not only in the track density, but also in the linear density.
The Dependence of the Diffusion Coefficient on the Proton Concentration in the Proton Exchange of LiNbO3
Authors: Kenchi Ito Kenchi Ito , Kazumi Kawamoto Kazumi Kawamoto
Published: October 2002

The concentration-dependent diffusion coefficient for proton-lithium counter-diffusion is studied in this paper. Depth profiles of the proton concentration for proton-exchanged LiNbO3 were measured by secondary ion mass spectroscopy (SIMS). The concentration-dependent diffusion coefficient for the proton-lithium counter-diffusion was calculated by the Boltzmann-Matano method and the relationships between the diffusion coefficient, the proton-exchange process, and the crystal phases in proton-exchanged LiNbO3 were examined. To confirm the validity of the diffusion coefficient calculated from the SIMS data, the depth profiles of the proton concentrations were numerically computed with the calculated diffusion coefficient and the exponential dependence of the diffusion coefficient on the content of lithium benzoate for dilution was reproduced.
Synthesis of Solid Solutions Based on the Akermanite and/or Hardystnite Systems and Their Fluorescence Properties
Authors: Kakitani Satoru , Ishii Hiroshi , Kazuhiro Yamaguchi Kazuhiro Yamaguchi
Published: October 2002

We investigated the incorporation of Eu into Akermanite and Hardystnite crystals and the fluorescence properties of the substances and we found that Eu was incorporated into Akermanite or Hardystnite only when it was co-doped with Na. This procedure enabled limited substitution of Eu3+ for Ca, resulting in the emission of 600 nm red fluorescence under UV irradiation. Eu was, however, incorporated into Akermanite- or Hardystnite-based solid solutions, which were made by limited substitution of Sr for Ca as a form of Eu2+. These substances exhibited emission of blue-colored fluorescence with a spectrum peak around 500 nm. It was also found that Hardystnite and Sr-Hardystnite (Sr substituted for Ca) formed a continuous series of solid solution.
Microwave Dielectric Properties of the (1-x)La2/3TiO3–xLaAlO3System
Authors: Moon Jong H. , Park Hyun S. , Lee Kyung T. , Choi Ju H. , Yeo Dong H. , Yoon Seok J. , Kim Hyun J.
Published: October 2002

The microwave dielectric properties of the (1-x)La2/3TiO3–xLaAlO3system in which LaAlO3havingεr=22,Q·f0=46,000 (at 7 GHz), and τf=-40–-50 ppm/° C was incorporated with La2/3TiO3havingεr≥90 and positive τfwas investigated. The (1-x)La2/3TiO3–xLaAlO3crystal system was pseudo-cubic in the range 0.1≤x≤0.7. Its lattice constant increased with increasingxeven though the amount of LaAlO3containing Al(0.57 Å) ions which are smaller than Ti(0.64 Å) increased. As the amount of LaAlO3increased fromx=0.1 to 0.9, the relative dielectric constant (εr) decreased from 50 to 23 and the temperature coefficient of the resonant frequency (τf) decreased from +84 to -50. On the other hand, the value ofQ·f0reached a maximum (148000 at 9.7 GHz) atx=0.7, where a rapid increase in the peak intensity of XRD occurred, and further increased after prolonged sintering. The microwave dielectric properties ofεr=37,Q·f0=47000 GHz (f0=9 GHz), and τf=-2 ppm/° C were obtained near 0.6La2/3TiO3–0.4LaAlO3(x=0.4) composition.
Temperature Dependence of the Dynamical Behavior of Holographic Gratings Formed in Polymer Dispersed Liquid Crystal Films
Authors: Fuh Andy Ying-Guey , Tsai Ming-Shan , Chien Tsung-Chi Liu
Published: October 2002

Using films made of liquid crystal (LC), pre-polymer and photoinitiator dye mixtures, we fabricated holographic gratings under various curing temperatures. Mixtures having LC contents of 20 wt% and 40 wt% were prepared. Qualitative studies on phase separation using these mixtures were first conducted using a light scattering method. We then investigated the dynamical behavior of the gratings at various ambient temperatures. The grating morphologies were finally investigated using scanning electron microscopy (SEM). The results showed that no macroscopic phase separation was observed in the samples which have a LC content of 20 wt%. The thermal grating was found to dominate in the initial period during the formation of gratings on these films. Later, it was offset by the photopolymerization effect which eventually dominated and determined the characteristics of the final grating. For samples having a LC content of 40 wt%, the thermal grating effect was negligible, due to the molecular diffusions in these samples. The diffraction efficiencies of the final gratings were analyzed, and were found to have a good correlation with their SEM images.
Collective Fluctuation and Switching Behavior in an Antiferroelectric Smectic Subphase Appearing in the Devil's Staircase
Authors: Hiraoka Kazuyuki , Tsumita Takayo , Sugiyama Yutaka , Monzen Kazuhiro , Suzuki Yoshiko Uematsu
Published: October 2002

We present the fluctuational and switching behaviors in an antiferroelectric phase designated as the AF phase, which appears in a temperature region above the chiral smectic C
A
( SmC
A

*) phase of an antiferroelectric liquid crystal, (S)-4-(1-methylheptyloxy-carbonyl)phenyl 4'-octylbiphenyl-4-carboxylate. It has been confirmed that the relaxation of the Goldstone mode due to an antiferroelectric phase mode occurs in the AF as well as the SmC
A

* phase. In addition, we have found that the switching behavior of the AF phase depends on the frequency of an applied electric field. The typical tristable switching between AF and SmC* is observed under a triangular wave of frequencies lower than 0.1 Hz, though the field-induced intermediate phase appears around the frequency range corresponding to the relaxation of the Goldstone mode. We speculate the model responsible for the switching behavior of the antiferroelectric AF phase.
Stability of (C6H5C2H4NH3)2Pb(BrxI4-x) Mixed Crystals
Authors: Nobuaki Kitazawa Nobuaki Kitazawa
Published: October 2002

The stability of (C6H5C2H4NH3)2Pb(Br

x

I4-
x

) mixed crystals was investigated and the degradation process was discussed. A thin film of microcrystalline (RNH3)2PbBr4 was more stable than that of (RNH3)2PbI4, and the stability of (C6H5C2H4NH3)2Pb(Br

x

I4-
x

) mixed crystals was improved by the replacement of I with Br. X-ray diffraction and optical absorption measurements suggested that the (RNH3)2PbI4 crystal changed to β-phenethylamine ( C6H5C2H4NH2) coordinated PbI2 with the elapse of time. In order to determine the origin of degradation, a light irradiation-induced degradation effect was also studied. The photochemical reaction was one of the possible reasons for degradation.
EPR Studies on the Effects of Dopant Cadmium (II) Ions on the Low Magnetic Dimensionality of Copper Calcium Acetate Hexahydrate
Authors: Samanta Rekha , A. K. Pal A. K. Pal
Published: October 2002

EPR investigations on Cd(II) doped copper calcium acetate hexahydrate of the composition Cu1-
x

Cd

x

Ca(Ac)4·6H2O (x=0.004–0.858) have been reported in the present communication. In the single crystal having as low as 0.4% Cd(II) concentration, single line spectrum having enhanced linewidth (7% enhancement) is obtained along the chain axis ( c-axis). For crystals having ≥8.2% Cd(II) concentration hyperfine structure appears. A large number of weak lines due to dimers, trimers and chains of finite length appear superimposed on the main line. It is inferred that Cd(II) impurity ions act as good reflectors and have profound influence on the spin diffusion process in the present 1D system. Along each of d- and e-axes in the tetragonal plane, doublet structures in the concentrated as well as in the dilute crystals are obtained. The doublet splitting (δH

d
) initially increases with increasing dilution; then the rate of increment gradually slows down and practically stops at Cd(II) concentration ∼55%. A model has been proposed to interpret the observed behaviour of δH

d
. Half-field lines due to forbidden ΔM
s=±2 transition within the dimer triplet have been observed in the dilute crystals.
Chemical Vapor Deposition of Nickel Oxide Films from Bis-π-Cyclopentadienyl-Nickel
Authors: Wen-chang Yeh Wen-chang Yeh , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Bis-π-cyclopentadienyl nickel has been proposed as a source material for metalorganic chemical vapor deposition of nickel oxide films. The transparent film deposited at 310°C was of a NaCl-type crystal structure of NiO. The refractive index and optical bandgap were approximately 2.1 and 3.7 eV, respectively.
Formation of Carbon Nitride Films by Helicon Wave Plasma Enhanced DC Sputtering
Authors: Zhang Jin Quin , Setsuhara Yuichi , Kyoh Shoji Miyake
Published: October 2002

Carbon nitride films have been synthesized on Si(100) substrates by using DC sputtering assisted with a high density m=0 mode helicon wave-excited plasma in Ar and N2 mixture. The composition, structure and bonding state of the films were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. From the XPS analysis it was found that the nitrogen to carbon (N/C) ratio in the films could be controlled over a wide range of 0.2–0.9 by changing the target voltage and nitrogen mixing rate via the production of a high density plasma of 1012–1013 cm-3. FT-IR spectroscopy indicated the appearance of an absorption band near 2200 cm-1 corresponding to C≡N covalent bonding. The XPS analysis also suggested the existence of a β-C3N4 phase with sp3 bonding correlated with the variation of the film microhardness.
Improved Response Time of Al–Al2O3–Pd Tunnel Diode Hydrogen Gas Sensor
Authors: Sumio Okuyama Sumio Okuyama , Hirotake Usami Hirotake Usami , Katsuro Okuyama Katsuro Okuyama , Hiroyuki Yamada Hiroyuki Yamada , Koichi Matsushita Koichi Matsushita
Published: October 2002

An Al–Al2O3–Pd tunnel diode acts as a sensitive hydrogen gas sensor. A serious drawback, however, of this hydrogen gas sensor operating at room temperature was a very long response time, typically 30 min. To overcome this disadvantage, the Pd tunnel diode was operated at elevated temperatures, resulting in a marked reduction of the response time, less than 1 min at 83°C. A microheater attached to the back surface of the substrate could be an efficient power source to heat the hydrogen sensor to the required temperature.
Contact Angle and Atomic Force Microscopy Study of Reactions of n-Alkyltrichlorosilanes with Muscovite Micas Exposed to Water Vapor Plasmas with Various Power Densities
Authors: Tohru Nakagawa Tohru Nakagawa , Mamoru Soga Mamoru Soga
Published: October 2002

Monolayers of n-alkyltrichlorosilanes (CH3(CH2)

n
-1SiCl3: Cn) were formed on the surface of Muscovite micas after various numbers of reactive sites were formed on the mica surfaces by exposing the micas to water vapor plasmas whose power, P, varied from 0 to 100 W. Contact angle measurements of the monolayers showed that the coverages of Cn molecules at n≦8 on the mica surfaces increased with an increase in the plasma power on the micas. On the other hand, the coverages of Cn molecules at n>8 on the micas were not so sensitive to the plasma power as those at n≦8. The atomic force microscopy (AFM) observations of the growth process of the monolayers from C18 showed that island structures were formed on the mica surfaces at the low coverages of the monolayers and that each island grew and eventually came into contact with the other islands as the coverage increased. In contrast, island structures were not observed on the mica surfaces during the growth process of C4 monolayers. These results propose a reaction model of Cn molecules with micas, where Cn molecules at n>8 are hydrolyzed with adsorbed water on the micas in the Cn solutions, followed by condensing to form two-dimensional polymerized network domains; Cn molecules at n≦8 are hydrated with the adsorbed water on the micas in the Cn solutions, but the domain sizes of the two-dimensional polymerized network are not so large as those at n>8 because of a limitation of the condensation among the molecules.
Observation of Mixed Fatty Acid Monolayer at the Air-Water Interface Using Phase Contrast Microscopy
Authors: Hirotaka Hosoi Hirotaka Hosoi , Hideki Akiyama Hideki Akiyama , Eiji Hatta Eiji Hatta , Toshio Ishii Toshio Ishii , Kōichi Mukasa Kōichi Mukasa
Published: October 2002

We observed stearic and lignoceric acids, and their mixed fatty acid monolayers at the air-water interface in situ using phase contrast microscopy. It was found that these monolayers exhibit quite different cohesion processes depending on the surface pressure. For stearic acid, the domains of the monolayer on the subphase have smooth surfaces and change their shapes to cover free areas with increasing surface pressure. In contrast, the domains of lignoceric acid divide into a number of smaller domains to cover free areas as surface pressure increased. We also found that the domains of lignoceric acid monolayers have internal substructures (i.e., triangular and inhomogeneous). For the mixed fatty acid monolayers, we clearly observed that some domains have the same internal substructures as those of single component monolayers. These facts demonstrate that a phase contrast microscope is a powerful tool for investigating the cohesion process of fatty acid monolayers at the air-water interface without the need for any probe material.
Simultaneous Measurements of Plasma Flow and Ion Temperature Using the Asymmetric Double Probe
Authors: Maeda Mitsuru , Uehara Kazuya , Amemiya Hiroshi
Published: October 2002

The asymmetric double probe method is extended to measure not only the ion temperature but also plasma flow in the tokamak edge plasma under a strong magnetic field. The plasma flow or the Mach number is determined by the ratio of ion saturation currents of the double probe pins, where the axes of the cylindrical pins are oriented perpendicular to the magnetic field and face up- or downstream. An experiment was performed in the JFT-2M tokamak.
Effect of Magnetic Field and Hydrostatic Pressure on Martensitic Transformation and Its Kinetics
Authors: Kakeshita Tomoyuki , Saburi Toshio , Kindo Koichi , Endo Shoichi
Published: October 2002

We performed recent studies on the effects of magnetic field and hydrostatic pressure on martensitic
transformations in some ferrous and nonferrous alloys. The studies clarified the effects of
magnetic field and hydrostatic pressure on martensitic transformation start temperature, the nature of
magnetoelastic martensitic transformation and the morphology of martensites and transformation kinetics
of athermal and isothermal transformations. Transformation start temperatures of all ferrous alloys
examined increase with increasing magnetic field, but those of nonferrous alloys, such as Ti–Ni and
Cu–Al–Ni shape memory alloys, are not affected. On the other hand, the transformation start
temperature decreases with increasing hydrostatic pressure in some ferrous alloys, but
increases in Cu–Al–Ni alloys. The magnetic field and hydrostatic pressure dependences of the
martensitic start temperature are in good agreement with those calculated by our proposed equations.
While investigations in the work on the ferrous Fe–Ni–Co–Ti shape memory alloy, we
found that magnetoelastic martensitic transformation appears and, in addition, several martensite
plates grow nearly parallel to the direction of the applied magnetic field in the specimen of Fe–Ni
alloy single crystal.
We further found that the isothermal process in Fe–Ni–Mn alloy changes to the athermal
one under magnetic field and the athermal process changes to the isothermal one under
hydrostatic pressure. Based on these facts, a phenomenological theory was constructed, which unifies
the two transformation processes.
P and As Implantation Enhanced Formation of Metal-Free Oxide on WSi2
Authors: Lee Jae-Gab , Kim Ji-Young , Lee Jeong-Yong , Roh Jae-Sung , Huh Jeung-Soo
Published: October 2002

We investigated the oxidation of crystallized tungsten silicide. We also researched the effects of preimplantation by P (or As) on the oxidation. Our results showed that the oxidation involved decomposition of the tungsten disilicide and consumption of the underlying polycrystalline silicon (polysilicon), consequently causing serious reliability problems. Cross-sectional transmission electron microscopy (XTEM) analysis showed that the oxide consisted of crystalline WO3 and amorphous SiO2, which was not removed completely using chemical solutions such as 100:1 HF and 7:1 buffered oxide etchant (BOE). However, P (or As) implantation prior to oxidation produced a SiO2 layer free of tungsten oxide. In particular, phosphorous implantation into silicide yielded a much thinner SiO2 layer on the silicide than As, which might be attributed to the presence of P2O5 in the oxide.
Heavily Sn-doped n-Type InGaP Grown by Metalorganic Chemical Vapor Deposition
Authors: Kazuhiro Nakamura Kazuhiro Nakamura , Takashi Fuyuki Takashi Fuyuki , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

Heavily Sn-doped InGaP layers were grown on GaAs substrates by atmospheric-pressure metalorganic chemical vapor deposition, using trimethylindium (TMIn), trimethylgallium (TMGa) and tertiarybutylphosphine (TBP) as source gases and tetraethyltin (TESn) as an n-type dopant gas. The doping properties of n-type InGaP epitaxial layers were studied using C-V measurements, Hall effect measurements and secondary ion mass spectrometry (SIMS). The carrier concentration can be controlled reproducibly in the range of 1018 to 1019 cm-3 and the maximum carrier concentration of 1.3 ×1019 cm-3 was achieved. The Sn donors incorporated in the InGaP layers are sufficiently activated.
Superconductivity of (La,A)MnO3/YBa2Cu3Oy Trilayer Films (A=Sr, Ca)
Authors: Inokuma Yoshihiro , Masaki Kanai Masaki Kanai , Tomoji Kawai Tomoji Kawai
Published: October 2002

Heteroepitaxial trilayer films in which a high-T
c superconducting YBa2Cu3O

y

(YBCO) layer is sandwiched by ferromagnetic oxide layers of La0.7Sr0.3MnO3 (LSMO) or La0.8Ca0.2MnO3 (LCMO) are formed by the laser molecular beam epitaxy method. When the thickness of each layer was 200 Å, the LSMO-YBCO trilayer film showed both superconductivity and ferromagnetism at low temperature. The superconducting transition temperatures (T
c) of the LSMO-YBCO and LCMO-YBCO trilayer films were lowered by decreasing the thickness of YBCO, and the T
c lowering in LCMO-YBCO films is slower than that in LSMO-YBCO films. This result suggests that the main cause of the T
c decrease is lattice mismatch between the superconductor and the ferromagnetic conductor, since the lattice mismatch of LCMO-YBCO is smaller than that of LSMO-YBCO.
Preparation of Epitaxial Au/Co Superlattices with High Perpendicular Magnetic Remanence by Molecular Beam Epitaxy
Authors: Toshiki Kingetsu Toshiki Kingetsu
Published: October 2002

The Au/Co superlattices are known to exhibit strong perpendicular magnetic anisotropy. However, the remanence and coercivity of the epitaxial superlattices reported in earlier papers were rather small at room temperature. In this study, we have prepared epitaxial Au/Co superlattices with perpendicular magnetic anisotropy that possess full remanence and considerable coercivity at room temperature. The samples were grown on 5-nm-thick Cu seed layers formed primarily on 7×7-(111)Si substrates at 50°C by molecular beam epitaxy.
Analytical Modelling of Active-Matrix Driving of Liquid Crystals with Spontaneous Polarization
Authors: Ton Verhulst Ton Verhulst
Published: October 2002

Analytical equations are derived for the static and dynamic behaviour of analog responding liquid crystals (LCs) with spontaneous polarization under active-matrix driving. The calculated results are compared with measurements and are found to be in agreement. For LCs with high spontaneous polarization and driven by short pulses, a large storage capacitor per pixel is needed to obtain an acceptable voltage sensitivity of the display. As regards the dynamic behaviour, a step in the drive voltage results in a transmission which oscillates around and towards the final value during a number of frames. This number of frames depends on the width of the drive pulses and the value of the storage capacitor, both in relation to the properties of the LC. In Appendix A, measuring methods are described for the characteristic parameters of analog responding LCs with spontaneous polarization.
Stabilization of a Laser Diode with an Intracavity Cesium Cell
Authors: Hagimoto Ken , Akulshin Alexander M. , Shin-ichi Ohshima Shin-ichi Ohshima , Yasuki Koga Yasuki Koga
Published: October 2002

The frequency of a laser diode (LD) with an intracavity cesium cell was stabilized optically by the nature of the atoms in the cell. The injection current and the position of the reflecting mirror were simultaneously controlled to maintain the optimum condition by modulating the injection current and using the phase sensitive detection. The experimental setup was simple and the linewidth became narrower than 100 kHz.
Fluorescence Lifetime of Organic Thin Films Alternately Deposited with Diamine Derivative and Aluminum Quinoline
Authors: Mori Tatsuo , Obata Kouji , Miyachi Kiyokazu , Kawakami Teruyoshi Mizutani
Published: October 2002

Fluorescence lifetimes of organic thin films alternately deposited with diamine derivative (TPD) and aluminium quinoline (Alq3) were measured. The alternating deposition structure was shown to enhance the emission from Alq3 in spite of imperfect film structures. Energy transfer from TPD to Alq3 was evidenced by the correlation between lifetime and period number. It was found to be a competitive process with the TPD radiation process, and its rate of TPD radiation was estimated to be 1.2×1010 s-1. The authors suggested that the presence of the region mixed with TPD and Alq3 at the TPD/Alq3 interface plays an important role in the electroluminescence (EL) process. The Alq3 exciton confinement was clarified experimentally since the component of the faster fluorescence lifetime of Alq3 increased in the short-wavelength region. In addition, the authors proposed a possible EL model based on the suppression of the thermal inactivation of Alq3 excitons during their diffusion.
Molecular Dynamics Simulations of the Behavior of Small Interstitial Clusters in Copper
Authors: Ping Zhao Ping Zhao , Yoshiharu Shimomura Yoshiharu Shimomura
Published: October 2002

Molecular dynamics (MD) simulations are carried out to study the behavior of small interstitial clusters in copper using a semi-empirical many-body potential of the embedded atom method (EAM). In this paper, a set of values of formation, binding and migration energy calculated for single, di-, tri-, tetra-, penta- and hexa-interstitial are reported. Their stable configurations and migration mechanisms are also presented. The results show that the small interstitial clusters have a significantly low migration energy and move in the form of one-dimensional crowdion migration, which indicates that they have a high mobility relative to the single interstitial. The results are also compared with available experimental investigations and previous interstitial calculations using pair potentials.
X-Ray Rocking Curve Study of the Strain Profile Formed by MeV Ion Implantation into (111) Silicon Wafers
Authors: Kuribayashi Masaru , Takumi Katsuhiko , Inoue Akira , Tanaka Hiroyuki , Tomita Hirofumi , Jiang Yi-Chao , Katoh Hiroyuki , Ishida Kohtaro , Aizawa Kazuya , Okayasu Satoru , Tomimitsu Hiroshi , Kazumata Yukio
Published: October 2002

Ni, Cu and Au ions were implanted into silicon (111) wafers at irradiation energies of 80–230 MeV with doses of 0.1–5.0×1014 atoms/cm2. X-ray rocking curves from the wafers were investigated using the dynamical diffraction theory. Strain profiles obtained by curve fitting revealed that the energy loss per unit length (energy deposition) due to a nuclear collision played an important role in the expansion of the lattice spacing. The height of the main peak of the strain profile was proportional to the dose of ion implantation. In the case of Au implantation, an additional distortion near the crystal surface and a uniform expansion of the lattice spacing in the distorted layer were observed.
Effect of Utilizing Hydrogen-Treated Tantalum Anodized Oxidation on Symmetry of Current–Voltage Characteristic of Metal–Insulator–Metal Element
Authors: Liu Hongwu , Wu Yuan , Yuan Jianfeng , Kai Ma Kai Ma , Ximin Huang Ximin Huang
Published: October 2002

The symmetry of current–voltage ( I–V ) characteristic of the metal–insulator–metal (MIM) element with the insulator of tantalum anodic oxidation TaO

x

which is heat-treated in hydrogen (hydrogen-treated) is greatly improved. Meanwhile, the symmetric I–V characteristic, unlike that of the conventional MIM element with tantalum anodic oxidation TaO

x

which is heat-treated in vacuum (vacuum-treated) or in an oxygen atmosphere, is independent of the choice of top-electrode material. In addition, the making process of the MIM element with hydrogen-treated TaO

x

film is less than that of the conventional MIM element with vacuum-treated TaO

x

film. Considering the oxide layer structure, we present a novel p–n-–n band model for MIM element to explain these experimental phenomena.
Strain Mechanism of LiNbO3/Sapphire Heterostructures Grown by Pulsed Laser Deposition
Authors: Shibata Yoshihiko , Kuze Naohiro , Matsui Masahiro , Kanai Masaki , Kawai Tomoji
Published: October 2002

Thin LiNbO3 films are deposited on (001) sapphire substrates by a pulsed laser deposition technique. The epitaxial growth of the films is confirmed by high-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (TEM) analyses. The lattice parameters and thermal expansion coefficients of the films are determined by an XRD technique. The deposited films are strained at room temperature, that is, the a-axis is longer and the c-axis is shorter than those of LiNbO3 single crystals. On the contrary, the films are not strained at the deposition temperature of 735° C. The strain of the films is caused by the large differences in the thermal expansion coefficients between LiNbO3 and sapphire substrates.
Molecular Switching in Phospholipid and Azobenzene Mixed Monolayers Using Maxwell-Displacement-Current-Measuring Technique
Authors: Xiaobin Xu Xiaobin Xu , Mitsumasa Iwamoto Mitsumasa Iwamoto
Published: October 2002

Molecular switching in phospholipid and azobenzene mixed monolayers was examined by Maxwell-displacement-current (MDC) measurement in combination with the surface pressure measurement. It was found that the molecular aggregation of pure azobenzene monolayers was reduced by the introduction of phospholipids possessing unsaturated long alkyl chains (DOLPC) or saturated long alkyl chains (D-DPPC). The surface pressure change was detected from mixed monolayers over the entire range of molecular area with alternating irradiation of ultraviolet and visible light. On the one hand, MDC was generated from DOLPC-azobenzene mixed monolayers over the entire range of the molecular area, whereas the generation of MDC from D-DPPC-azobenzene mixed monolayers was limited in the molecular area. We discussed the generation of MDC from phospholipids-azobenzene mixed monolayers in combination with the surface pressure change measurement.
Nature of Tip-Sample Interaction in Dynamic Mode Atomic Force Microscopy
Authors: Kageshima Masami , Imayoshi Takahiro , Yamada Hirofumi , Nakayama Kan , Sakama Hiroshi , Akira Kawazu Akira Kawazu
Published: October 2002

The dependence curve of the resonance frequency shift of a dynamic mode atomic force microscope (AFM) cantilever on the distance between the tip and the sample is examined. For a system with clean semiconductor sample and a metal-coated tip, the obtained curve exhibited a larger frequency shift compared to one with a uncoated Si tip, and an increasing deviation from van der Waals characteristics as the separation decreased. This is due to an additional attractive force which becomes dominant at a small separation. This force is considered to play a crucial role in high-resolution imaging of semiconductor surfaces with a dynamic mode AFM.
Anatase-Type TiO2 Thin Films Produced by Lattice Deformation
Authors: Sugimura Wataru , Yamazaki Atsushi , Shigetani Hisashi , Tanaka Junzo , Mitsuhashi Takefumi
Published: October 2002

TiO2 thin films were grown onto SrTiO3 substrates by a molecular beam epitaxy (MBE) method using an oxygen radical source. The structure of the thin films obtained was evaluated by X-ray reflection diffractometer (XRD) and reflection high energy electron diffraction (RHEED); TiO2 thin films were determined to be of anatase type and were epitaxially grown in the direction of the c-axis, parallel to the [001] of the substrates. Near the interface, the a-value of thin films increased and the c-value shrank in comparison to that of anatase powder. These results indicated that the anatase phase of TiO2 was induced by a lattice matching process at the interface between SrTiO3 and TiO2.
A Proposal to Increase the Count Rate of a Discharge-Type UV Detector
Authors: Igarashi Ryuji , Takashima Atsushi , Takahashi Yoshiaki , Yukio Iwaya Yukio Iwaya , Masato Sakata Masato Sakata
Published: October 2002

An attempt to increase the count rate of a discharge type UV detector is presented in this report. The proposed principle is to decrease the dead time of the detector by reducing the recovering time of the driving circuit. With the recommended resistor-capacitor circuit, an appreciable reduction is impossible. The reduction is realized by a transistor switch.
Mid-Infrared Photoluminescence from Liquid Phase Epitaxial InAs 1-ySby/InAs Multilayers
Authors: Gong XiuYing , Yamaguchi Tomuo , Kan Hirofumi , Makino Takamitsu , Rowell Nelson L. , Lacroix Yves , Mangyou Atsuo , Aoyama Mitsuru , Kumagawa Masashi
Published: October 2002

Photoluminescence for InAs1-y
Sb
y
multilayers grown on InAs substrates by liquid phase epitaxy has been investigated. A 5 K luminescence peak wavelength longer than 5 µm with a full-width at halfmaximum of 10 meV has been obtained. The compositional and temperature dependence of the PL spectra were studied. A band gap energy shift of 50 meV between 5 and 300 K was observed. The results indicate the high quality of the materials. Light emitting diodes with wavelength of 4.2 µm at 77 K have been obtained. The potential applications for a light source operating in 3–5 µm were demonstrated.
Descaling Behavior of Type430 Hot-Rolled Stainless Steel Coil
Authors: Ito Masahiko , Tachibana Rinso , Seino Yoshikazu , Yamamoto Akira , Kawabata Yoshikazu , Uchino Kazuhiro
Published: October 2002

Iron oxides can be reduced in a scale by batch annealing treatment in a reducing atmosphere of 7 vol% H2+93 vol% N2 at 1123 K for hot-rolled coils of type430 stainless steel. The heating processes cause cracks, a Cr2O3 layer in the scale and a Cr depleted layer on the substrate. It is possible to produce a large number of cracks in the scale by employing a scale breaker. The ease of descaling is positively related to the amount of bending elongation. Similarly with shot blasting, descaling becomes easier as the projection energy of the shot blasting increases. The pickling solution penetrates the scale through cracks on the surface of the strip, and its acid dissolves the stainless steel coil and part of the scale. The scale peels from the stainless steel coil in island-like exfoliation until the scale has been removed from the entire surface of the stainless steel coil.
Basic Study of Quantitative Ion Scattering Spectroscopy I Correction Factors for Quantification
Authors: Asahata Tatsuya , Onobu Masanori , Kondo Akio , Kang Ryuichi Shimizu
Published: October 2002

Basic problems in quantification by ion scattering spectroscopy (ISS), i.e., energy dependence of the detection efficiency of a micro channel plate (MCP) and neutralization probabilities, have been studied using a newly constructed time of flight (TOF)-ISS apparatus. For primary ion energy below keV (1) marked dependence of the detection efficiency of MCP on the signal energy, and (2) strong contribution, to the ISS spectrum, of those neutral signals that are backscattered through the collision with the second or subsequent atomic layer atoms have been clearly revealed. It has also been pointed out that the energy dependence of the detection efficiency is described very well by a simple statistical treatment of secondary electron generation in the detector.
The Generation of Period-2 Oscillation of a Single Bubble in the Transitional Region
Authors: Yoshitaka Murata Yoshitaka Murata , Yoshiaki Watanabe Yoshiaki Watanabe
Published: October 2002

The bubble oscillations in the transitional region driven by ultrasound are numerically calculated and analyzed. The oscillations in the transitional region in the process reaching the stationary oscillations contain important information to elucidate the nonlinear phenomena of a bubble. In particular, the bubble oscillations are treated on the condition that some kinds of tone burst waves with short cycles are applied as the driving sound of a bubble. As a result, it is revealed that the interactive frequency component between bubble resonance and driving sound plays an important role in the generation of period-2 oscillations. Precisely speaking, the period-2 oscillation grows under sufficiently high pressure amplitude, due to the self-positive feedback between the interactive component and the bubble resonance. To aid these analyses, a new mean dealing with the forced oscillation in the transitional region is introduced.
Hierarchical Processing of Levenson-Type Phase Shifter Generation
Authors: Kazuko Yamamoto Kazuko Yamamoto , Taiga Uno Taiga Uno , Kiyomi Koyama Kiyomi Koyama
Published: October 2002

The hierarchical processing of Levenson-type phase shifter generation has been developed. It is integrated with a computer aided design (CAD) system, which makes modification of conflict spots easy for designers. In order to keep CAD data compressed during phase assignment, phase information is stored as a combination of two properties, phase and group reversal. Phase assignment is generally executed cell-by-cell from the bottom up. In each cell, the region processed is kept to a minimum in order to achieve efficient processing. The intrinsic problem of bottom-up hierarchical processing is the merge problem in which patterns to be merged at the cell boundary have different phases, and it is treated with retry processing. The hierarchical phase assignment was applied to 4M-bit memory with a core circuit and the effectiveness of the hierarchical processing was demonstrated. The processed data were compressed to about 1/20, and processing time was reduced by at least 1/2 of those by flat processing.
Evaluation of Shaping Gain Adjustment Accuracy Using Atomic Force Microscope in Variably Shaped Electron-Beam Writing Systems
Authors: Nishimura Shinsuke , Sunaoshi Hitoshi , Yamasaki Satoshi , Hattori Kiyoshi , Tamamushi Shuichi , Wada Hirotsugu , Ogawa Yoji
Published: October 2002

A method for the fine evaluation of shaping gain adjustment, in which resist patterns are measured using an atomic force microscope (AFM), has been explained for the variably shaped electron-beam (EB) writing systems. The shaping gain coefficient was adjusted so that the length between two beams deflected by a shaping deflector is equal to a parameter given to the writing system. For the evaluation of the absolute values of the adjustment, the authors drew line and space patterns on a poly-methyl methacrylate (PMMA) resist. The authors measured the resist height at the shot boundary with an AFM. When the beam size is equal to the shot pitch, the resist height at the shot boundary becomes zero. From the beam size and the shaping-gain shift at which the resist height at the shot boundary becomes zero, beam-size error was calculated. From the beam-size error for various beam sizes, the shaping gain adjustment error of 0.3 nm for the 1 µ m beam size and the shaping-offset error of 6.0 nm have been obtained.
Fabrication of Micro-Marks for Electron-Beam Lithography
Authors: Jun Takamatsu Jun Takamatsu , Tetsuro Nakasugi Tetsuro Nakasugi , Yoshimitsu Kato Yoshimitsu Kato , Naoharu Shimomura Naoharu Shimomura , Hitoshi Sunaoshi Hitoshi Sunaoshi , Kiyoshi Hattori Kiyoshi Hattori , Kazuaki Nakajima Kazuaki Nakajima , Kazuyoshi Sugihara Kazuyoshi Sugihara , Tadahiro Takigawa Tadahiro Takigawa
Published: October 2002

We have developed micro-marks to be used for precise adjustment of the electron optics in electron-beam writers. The micro-marks fabricated are the dot-mark of W on a Si substrate, the hole-mark on a W layer, and the hole-mark on a Au layer. With these marks, it is possible to precisely measure the edge resolution as well as the two-dimensional shape and size in the variably shaped beam (VSB) and the character projection (CP) lithography. Measuring the edge resolution of shaped beam in 50 keV electron-beam writer with these marks, we found that the hole-mark on a W layer gave the best resolution and contrast. These results show that these marks are applicable to lithography of 0.15 µm or below.
A Principle of Deposition of Ultra Low and Uniform Stress Absorber for X-Ray Mask
Authors: Kitamura Kaeko , Yabe Hideki , Sasaki Kei , Ami Shigeto , Kise Koji , Sunao Aya Sunao Aya , Kenji Marumoto Kenji Marumoto
Published: October 2002

We investigate the deposition of ultra low and uniform stress absorbers for highly accurate X-ray masks. We calculate the maximum overlay error between two masks having different absorber coverages as parameters of absorber stress peak-to-valley (pv) value and distribution shape in order to establish the criteria of absorber stress, which suggested that less than 10 and 6 MPa uniformity was required for 30 and 50 mm windows respectively to achieve the mask overlay of less than 5 nm. Then we perform several experiments to optimize the sputtering conditions from the viewpoint of the geometric relation between a sputtering target and mask substrates. We observe that the target-substrate (T-S) distance in the axial direction changes only the average stress, but does not affect the uniformity, while the T-S distance in the parallel direction affects both the average and distribution. A very uniform stress absorber of ±3 MPa for a 25 mm square area is deposited 60 mm away from the target center. From further experiments, we establish a simple but important principle that the linear stress distribution on the stage deposited without rotation cancels out by rotating the substrate, and as a result the absorber stress becomes sufficiently uniform.
Critical Dimension Control in Synchrotron Radiation Lithography Using a Negative-Tone Chemical Amplification Resist
Authors: Sumitani Hiroaki , Watanabe Hiroshi , Itoga Kenji , Hifumi Takashi , Suita Muneyoshi , Ogushi Nobuaki , Mizusawa Nobutoshi , Uda Koji
Published: October 2002

Total critical dimension (CD) controllability for 0.14 µ m line-and-space in SR lithography was evaluated for all wafer levels. The evaluation was carried out for the CD accuracy between the wafers, in the wafer and in the exposure field. The influence of the exposure process instability to the CD accuracy was also evaluated. The instability of the post exposure baking (PEB) temperature and the post exposure delay (PED) time affects the CD accuracy, and they were estimated to be less than 5 nm, respectively. The CD accuracy at the same point on the X-ray mask was 5.4 nm in the wafer and 10.5 nm between the wafers. It was found that the CD accuracy between the wafers was degraded by the inaccurate exposure dosage caused by the daily change of the SR beam distribution in the vertical direction. In the exposure field, the CD instability due to SR beam nonuniformity was 4.1 nm and that due to the X-ray mask was 15 nm. Consequently, the total CD controllability is presently estimated to be 19.5 nm for all wafer levels and the improvement of the dose repeatability and X-ray mask CD control is required to achieve the CD accuracy of less than 11 nm.
A Novel Design of Three-Aspherical-Mirror Imaging Optics for Extreme Ultra-Violet Lithography
Authors: Watanabe Takeo , Mashima Kiyoto , Masahito Niibe Masahito Niibe , Hiroo Kinoshita Hiroo Kinoshita
Published: October 2002

The demagnifying optics for extreme ultra-violet lithography (EUVL), which consists of three aspherical mirrors and one plane mirror, is proposed. A resolution of 0.1 µ m can be achieved on a ring field of 26 mm×1 mm in size and the blur size owing to the distortion is small. The assembly tolerance such as decentration tolerance and tilt tolerance is investigated for each of the aspherical mirrors. It is clarified that the assembly accuracy requires 0.0015 degree for the proposed optics.
Dissolution Inhibitors for 193-nm Chemically Amplified Resists
Authors: Ushirogouchi Tohru , Asakawa Koji , Okino Takeshi , Shida Naomi , Naoko Kihara Naoko Kihara , Makoto Nakase Makoto Nakase
Published: October 2002

Dissolution characteristics and adhesion of 193-nm resists have been investigated by using molecular orbital calculations. The calculation indicated that naphthalene compound had better adhesion than alicyclic compounds by a factor of 1.2. Another calculation result obtained indicated that naphthalene was more hydrophilic than alicyclic compounds. In order to improve the adhesion and dissolution characteristics of the alicyclic resist, introduction of the naphthalene backbone into alicyclic resists was attempted in the form of additives (dissolution inhibitors) or copolymer components. Dissolution inhibitors that have simultaneously a naphthol novolak backbone and a characteristic generate carboxylic acid, such as tetrahydropyranyl ester of naphthol novolak compound condenced with glyoxlic acid (NV4THP), were the most effective dissolution inhibitors increasing dry etch resistance of base polymer by 14% and pattern resolution of original resist by 10%. The naphthalene dissolution inhibitor also largely improves pattern adhesion. These results were consistent with above-mentioned calculation results. 193-nm resists containing vinyl naphthalene in the copolymer structure were also investigated and fundamental resist requirements were satisfied with this polymer by adding adamantane dissolution inhibitor di-tert-butyl 2-((1-adamanthyl)carbonylmethyl) malonate (ADTB).
Consideration of Silylation Contrast in an ArF Liquid-Phase Silylation Process
Authors: Matsuo Takahiro , Endo Mitsuhiro Ohkuni
Published: October 2002

We have studied what determines the silylation contrast for the liquid-phase silylation process in ArF excimer laser lithography. In the liquid-phase silylation, the diffusion kinetics is dependent on the concentration of the diffusion promoter, which acts as the relaxation of the polymer film. The silylating condition of a proper concentration induces the equilibrium state of relaxation and diffusion: Case II diffusion. It was found that the Case II diffusion condition resulted in a higher silylation contrast. Next, attention was paid to the photo-crosslinking density for improving the silylation contrast. The soft-baking temperature had an influence on the crosslinking density. The densification of the polymer film by soft-baking increases the photo-crosslinking density, but an extreme densification decreases it, when the soft-baking temperature is near glass transition temperature (T
g). It is considered that the arrangement of the polymer chains is closely linked with the efficiency of photo-crosslinking.
Charge Injection and Generation in Nematic Liquid Crystal Cells
Authors: Shuichi Murakami Shuichi Murakami , Hiroyoshi Naito Hiroyoshi Naito
Published: October 2002

Charge injection and generation in nematic liquid crystal (NLC) cells have been studied by measuring the steady state currents and capacitances of NLC cells. The steady state current is attributable to the charge injection from the electrode at the lower applied dc voltages, while the steady state current is due to the generation of mobile ions by the Poole-Frenkel effect in the NLC bulk at the higher applied dc voltages. The width of electrical double layers, the desorption energy of the ions, and the interionic spacing of the positive and negative ions created by the Poole-Frenkel effect are estimated from the steady state current data.
X-Ray Microfabrication at the Center for Advanced Microstructures and Devices (CAMD)
Authors: Chantal Khan Malek Chantal Khan Malek , Volker Saile Volker Saile
Published: October 2002

The Center for Advanced Microstructures and Devices (CAMD) has established infrastructure and experience for deep X-ray lithography and functions as a print-shop for high aspect ratio microstructures in the US. A major up-grade of the facility will be completed by the end of 1997. It includes the installation of a wavelength shifter as a hard X-ray source for ultra-deep X-ray lithography and for cost effective, batch fabrication of high aspect ratio micro-components. This paper describes the X-ray micromachining facility and programs at CAMD. The scientific and engineering activities exemplified by results of current studies are reported.
Si Field Emitter Arrays Fabricated by Anodization and Transfer Technique
Authors: Higa Katsuya , Kiyoaki Nishii Kiyoaki Nishii , Tanemasa Asano Tanemasa Asano
Published: October 2002

Field emitter arrays made of single-crystal Si are fabricated by anodization and transfer techniques. The anodization of Si which has n/p junctions produces field emitter tips. The emitter tips are then transferred to another Si substrate by the direct bonding. It has been found that an optimum doping range exists for successful bonding and transfer of the emitter tips. Field emission characteristics of field emitter arrays thus fabricated are also reported.