bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial Cross Sections for Electron Impact Dissociation of CF4 into Neutral Radicals
Authors: Tohru Nakano Tohru Nakano , Hideo Sugai Hideo Sugai
Published: February 2005

The electron energy dependence of partial cross sections for dissociation of carbon tetrafluoride (CF4) into neutral radicals CF3, CF2 and CF has been measured. This was accomplished with threshold-ionization mass spectrometry in a differentially pumped dual-electron-beam device. The threshold energy for dissociation into each neutral radical was measured for the first time to be 12.5 eV, 15.0 eV and 20.0 eV for CF3, CF2 and CF radicals, respectively. The absolute cross sections for electron impact energy between 10 and 300 eV were determined through measurements of the radical sticking coefficient and electron-impact nitrogen dissociation. The magnitude of the cross section at its maximum is 0.39×10-20 m2 at 120 eV for CF3 radical, 0.22×10-20 m2 at 130 eV for CF2 radical, and 0.21×10-20 m2 at 110 eV for CF radical.
Efficient Optical Phase Conjugation in Methyl-Orange-Doped Polyvinyl Alcohol Film
Authors: Egami Chikara , Kazuo Nakagawa Kazuo Nakagawa , Hirofumi Fujiwara Hirofumi Fujiwara
Published: February 2005

An efficient optical phase conjugate (PC) wave in methyl-orange (MO)-doped polyvinyl alcohol (PVA) films by degenerate four-wave mixing (DFWM) is reported. As the wavelength concerned was far from the absorption center of the MO dye, a PC wave was generated more efficiently. For the configuration of mutually orthogonal-polarized pump and probe waves the PC reflectivity reached 30% at a wavelength of 531 nm and an intensity of 1 W/cm2 of a cw krypton-ion laser, by using a film with absorbance (=the product of the small-intensity absorption coefficient and the film thickness) of 2.1 at 531 nm. It was found that the photoinduced birefringence resulting from trans-cis isomerization, i.e., the real part of the nonlinear susceptibility χ2112, mainly contributed to generation of the PC wave at 531 nm.
Capacitive Dilatometer for Measurement of Oscillatory Magnetostriction
Authors: Matsui Hiroshi , Satomi Yanagida Satomi Yanagida , Terutaka Goto Terutaka Goto
Published: February 2005

A new type of capacitive dilatometer for the measurement of the oscillatory magnetostriction associated with the de Haas-van Alphen effect has been developed. The control of sample orientation allows for the survey of the field angle dependence of oscillatory intensity in the magnetostriction as well as the cross-sectional area of the Fermi surface. The precise control of the gap between the electrodes in the capacitive dilatometer at low temperatures provides for the detection of the oscillatory magnetostriction at high resolution better than δl/l=10-8. Application of this capacitive dilatometer to aluminum is discussed.
Photoconductivity Decay Characteristics of Undoped p-Type CuGaS2
Authors: Susaki Masami , Horinaka Hiromichi , Yamamoto Nobuyuki
Published: February 2005

Photoconductivity decay characteristics of undoped p-type CuGaS2 were measured at temperatures between 100 and 340 K to determine the carrier relaxation mechanisms correlated with some transition peaks in the excitation spectra. A direct recombination of free electrons and holes is observed for the intrinsic peak. For the extrinsic peak via a shallow donor, excited holes relax rapidly with a temperature-independent decay time of 5-8 µs, followed by electron decay with a temperature-dependent decay time. This results in a major recombination path between the conduction band and a shallow acceptor state. For the broad peak via a deep donor, a remarkable increase in decay time occurs above 250 K. This phenomenon is primarily caused by thermal emptying of the shallow acceptor state.
Measurement of Humidity Using Surface Acoustic Wave Device
Authors: Nomura Tooru , Oobuchi Ken , Furukawa Tsutomu Yasuda
Published: February 2005

A surface acoustic wave (SAW) sensor utilizing the acoustoelectric effect has been designed for measurement of humidity in sensing ambient atmosphere. Most of the studies reported on sensors utilize the effect of mass loading. In this paper, we propose a somewhat different SAW humidity sensor that uses the changes in the film conductivity rather than the mass. A 30 MHz dual SAW delay line fabricated on 128° YX LiNbO3 was coated with the sodium salt of poly(styrene) sulfonate. This hygroscopic polymer coating caused the SAW velocity change of 10 m/s per 10% relative humidity. The response was quite linear in the range from 20 to 70%RH.
Crystal Growth, Dielectric and Polarization Reversal Properties of Bi4Ti3O12 Single Crystal
Authors: Masuda Yoichiro , Masumoto Hiroshi , Baba Akira , Goto Takashi , Hirai Toshio
Published: February 2005

A Bi2O3-TiO2 phase diagram was determined using differential thermal analysis (DTA) apparatus. Bi4Ti3O12 (BIT) micalike single crystals grown by a flux method were clear and slightly grayish in color. Ferroelectric and dielectric properties of BIT crystals were observed from measurements of electric displacement vs electric field hysteresis loops and the dielectric constant. Also, the polarization switching characteristics of BIT crystals were investigated. The switching time and switching current density were read from the transient waveforms.
Influence of Poling Conditions on Properties of BaTiO3 Single Crystal
Authors: Nakao Osamu , Tomomatsu Kazuhiko , Ajimura Shoji , Akihito Kurosaka Akihito Kurosaka , Haruo Tominaga Haruo Tominaga
Published: February 2005

A BaTiO3 single crystal, whose dimensions were 3.9×3.9×3.6 mm3, was mechanically and electrically poled to remove its 90° and 180° ferroelectric domain walls, respectively. After mechanical poling, four-step electrical poling was applied to the crystal, which did not include 90° domain walls, with the aim of removing the 180° domains gradually. In each of these steps, the dielectric constant of the crystal was measured using an impedance analyzer. Prior to the electrical poling, the dielectric constant in the [001] direction was 137 at 100 kHz (unclamped) and 133 at 10 MHz (clamped). By applying four-step poling, these values varied gradually with the progress of poling, and became 130 and 58, respectively, after the final step, i.e., in a single-domain state.
Preparation of Sr(Zr, Ti)O3 Ceramics and Their Dielectric Properties at Microwave Frequencies
Authors: Yamada Akira , Utsumi Yoshikazu , Hisao Watarai Hisao Watarai , Ken Sato Ken Sato
Published: February 2005

Powder of the dielectric ceramic Sr(Zr, Ti)O3 was prepared by a new chemical method using TiO2 powder. The obtained fine and well-dispersed powder had good sinterability. The microscopic compositional uniformity in the sintered body was estimated by WDX, and the dielectric properties were measured at 6 GHz and 1 MHz. The samples prepared by the chamical method had excellent uniformity and a Q value (1/tan δ) 2.5 times that of the samples prepared by the conventional method.
Multiplexing Performance of Antiferroelectric Liquid Crystal Device
Authors: Yamamoto Norio , Yamada Yuichiro , Koshobu Nobuaki , Mori Kahoru , Nakamura Kohji , Orihara Hiroshi , Ishibashi Yoshihiro , Suzuki Yoshiichi , Kawamura Ichiro
Published: February 2005

A multiplex-driving technique for an antiferroelectric liquid crystal device has been studied. A new driving scheme is proposed, which overcomes the disadvantage of slow switching from a ferroelectric state to an antiferroelectric state. It is confirmed that the antiferroelectric liquid crystal device can be driven at a high duty ratio of 1/500 by using this scheme.
Electrooptic Modulation in the Optical Waveguide Using Ferroelectric Liquid Crystal
Authors: Ozaki Masanori , Sadohara Yutaka , Uchiyama Yasushi , Manabu Utsumi Manabu Utsumi , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

A fast electrooptic modulation in the polymer waveguide using ferroelectric liquid crystal has been proposed. In this device, the soft mode ferroelectric liquid crystal (SMFLC) is used as an active material on the passive polymer waveguide, and electrooptic switching is realized by controlling the total reflection at the polymer waveguide-liquid crystal interface. The response time is of the order of several microseconds. An analogue electrooptic modulation in the waveguide is realized using the field-induced linear molecular tilt of the electroclinic effect in SMFLC.
Antiferroelectric Properties and Their Surface Effect in Ferroelectric Liquid Crystal 3MC2PCPOPB
Authors: Moritake Hiroshi , Shigeno Nobuyuki , Masanori Ozaki Masanori Ozaki , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

A detailed study of dielectric and optical properties in ferroelectric liquid crystal (R)-4′-3(-methoxycarbonyl-2-propoxycarbonyl)phenyl 4-(4-(n-octyloxy)phenyl)benzoate (3MC2PCPOPB) has been carried out. It has been found that the anomalous temperature dependence of the dielectric constant in 3MC2PCPOPB is due to the antiferroelectric property. In the antiferroelectric phase, five stable states are observed in voltage dependence of apparent tilt angle, and on the basis of those measurements the T(temperature)-E(electric field) phase diagram is obtained. In a thin cell (<3 µm), both ferroelectric and antiferroelectric domains are simultaneously observed at the same temperature over a wide temperature range. Although the ratio of the area of antiferroelectric domains to that of ferroelectric domains gradually increases with decreasing temperature, a complete antiferroelectric phase does not appear even at low temperature.
Enhancement of Optical Wave Mixing Characteristics of Photorefractive Bi12SiO20 Crystal by Moving Grating Method
Authors: Yoshihara Toshiyuki , Iba Jun , Uesu Yoshiaki , Hikita Kazuyasu , Iizuka Hiroyuki
Published: February 2005

The moving grating method was applied to a photorefractive Bi12SiO20 crystal in order to enhance the light amplification factor γ0 in the two-wave mixing process and the reflectivity R of the phase conjugate wave in the four-wave mixing process. It was found that γ0 and R exhibited maximum values when the interference pattern moved inside the Bi12SiO20 crystal at an optimum velocity. We achieved 65% reflectivity of the phase conjugate wave at that velocity. The response time of the photoinduced refractive index grating was determined with varying incident beam intensity, external electric field and grating spacing.
Dielectric and Optical Studies of the Low-Temperature Phase in NaNbO3: Effect of Manganese Dopant
Authors: Molak Andrzej , Yamashita Akira Onodera
Published: February 2005

Pure and Mn-doped NaNbO3 crystals have been investigated dielectrically between 380 and 20 K. Below room temperature, no phase transition is observed in pure sodium niobate. With increasing Mn content, a structural phase transition is induced around 140 K. The dielectric constant shows a maximum for the sample with 0.7 wt.%, and shows large thermal hysteresis. In the low-temperature region, ferroelectric activities could not be detected in either pure or lightly doped NaNbO3. The phase diagram of T
c vs the concentration of Mn is obtained. Domain motion associated with this phase transition is observed around the transition temperature. This evidence proved that the low-temperature phase is induced by light doping with Mn ions. The uniaxial stress decreases T
c; dT
c/dσ=-80 K/kbar on heating and -600 K/kbar on cooling.
Humidity Dependence of Surface Resistances of LiNbO3 and LiTaO3 Single Crystals
Authors: Maeda Masaki , Sakiyama Ikuo Suzuki
Published: February 2005

Humidity dependence of the surface resistivity and the dielectric properties of adsorbed-water layers on the surfaces of LiNbO3 and LiTaO3 single crystals were examined. Experiments were carried out for the specimens with various cuts of the crystals to investigate the mechanism and the origin of the logarithmic dependence of the surface resistance on humidity.
Phenomenological Thermodynamic Theory for Pb(Zn1/3Nb2/3)O3-PbTiO3 Binary Solid Solution and Calculations for Phase Diagram, Dielectric Constants, Lattice Parameters and Piezoelectric Constants (New Estimation Method for Unknown Dielectric Stiffness Constants in Elastic Gibbs Free Energy for Binary System)
Authors: Takashi Yamamoto Takashi Yamamoto , Yoshihiro Terashima Yoshihiro Terashima
Published: February 2005

Unknown dielectric stiffness constants in elastic Gibbs free energy for Pb(Zn1/3Nb2/3)O3 were estimated by fitting the calculated phase diagram with the experimental one for the Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) solid solution, and by considering the discontinuity of the dielectric constant at the rhombohedral-tetragonal morphotropic phase boundary in the (1-x)PZN-(x)PT system, x>0.105. The calculated PZN=PT phase diagram using the newly estimated values was in good agreement with the experimental PZN-PT one. The dielectric constants, lattice parameters and piezoelectric constants of the PZN-PT system could be calculated at a given composition and temperature. On comparison with experimental data, this method was found to be effective for material design.
Thin-Film Long-Wire Antenna for 10.6 µm CO2 Laser Radiation
Authors: Shimizu Takashi , Yasuoka Yoshizumi , Gamo Kenji , Namba Susumu
Published: February 2005

Thin-film warm carrier devices which had 100-, 400- and 450-µm-long thin-film antennas were fabricated, and antenna properties at CO2 laser frequency were investigated. It was found that the fabricated thin-film antenna works as a long-wire antenna with electrical loss for CO2 laser radiation.
Intraband Relaxation Time in Compressive-Strained Quantum-Well Lasers
Authors: Park Seoung Hwan , Asada Masahiro , Kudo Koji , Arai Shigehisa
Published: February 2005

Intraband relaxation time is investigated theoretically for a compressive-strained quantum well by considering carrier-carrier and carrier-longitudinal optical (LO) phonon scattering mechanisms. It is found that the spectral broadening factor decreases from 10 meV in the lattice-matched quantum well to about 5 meV in the strained quantum well. This is mainly attributed to the reduction of the hole effective mass due to the strain effect. Dependence of the intraband relaxation time on carrier density and well width is also discussed.
Dielectric Behavior and the Devil's Staircase in the SmCα
* Phase of an Antiferroelectric Liquid Crystal, 4-(1-methylheptyloxycarbonyl)phenyl 4′-octylcarbonyloxybiphenyl-4-carboxylate
Authors: Hiraoka Kazuyuki , Takanishi Yoichi , Takezoe Hideo , Fukuda Atsuo , Isozaki Tadaaki , Suzuki Yoshiichi , Kawamura Ichiro
Published: February 2005

We have observed an increase of the dielectric constant under a bias electric field in the SmCA
* and SmCα
* phases in 4-(1-methylheptyloxycarbonyl) phenyl 4′-octylcarbonyloxybiphenyl-4-carboxylate. This implies a field-induced phase transition to the ferrielectric and/or to the ferroelectric phases. The transitions were also clearly observed in the field-induced apparent tilt angles in these phases. The electric-field-induced Devil's staircase was confirmed in the SmCα
* phase. Using these observations, a T(temperature)-E(electric field) phase diagram was drawn.
Structual Studies of Poly(Fluoroalkyl Methacrylate)s and Poly(Fluoroalkyl α-Fluoroacrylate)s
Authors: Koizumi Shun , Ohmori Akira , Shimizu Tetuo , Iwami Motohiro
Published: February 2005

Poly(fluoroalkyl methacrylate)s and poly(fluoroalkyl α-fluoroacrylate)s with various fluoroalkyl groups were prepared. These polymers were characterized for tacticity by proton and fluorine nuclear magnetic resonance (1H and 19F NMR) and investigated by Electron Spectroscopy for Chemical Analysis (ESCA) to assign each signal. We found that tacticity of poly(fluoroalkyl α-fluoroacrylate)s were independent of the fluoroalkyl structure. The relationship between the structure of polymers and ESCA signals for all polymers was clarified. Also, we found an orientation effect of fluoroalkyl groups on the surface of the polymer films through the analysis of F1s ESCA signals.
A Simple Method for Obtaining the Power Distribution Yielding a Desired Temperature Distribution in Zone-Melting Recrystallization
Authors: Byoung-Jin Yoon Byoung-Jin Yoon , Choong-Ki Kim Choong-Ki Kim
Published: February 2005

A simple one-dimensional method for obtaining the power distribution from a temperature distribution which is desirable for successful zone-melting recrystallization (ZMR) is proposed. The power distribution thus obtained can be realized by a tungsten-halogen lamp with a focusing mirror. The actual temperature distribution calculated by solving the heat flow equation two-dimensionally with the obtained power distribution as the input heat source shows very close agreement with the initially desired target, especially in the region where the temperature gradient must be controlled precisely. The enthalpy method has been used to incorporate the abrupt changes of the optical and thermal properties of silicon upon phase transition. It has been found that the temperature distribution is insensitive to some local changes in the input power distribution so that we can modify the input power distributions in such a way to make the mechanical processing of the focusing mirror easier. This method may be applied to systems other than the ZMR system which require the shaping of the temperature distribution.
Barrier Height Imaging Investigation of Liquid Crystal Molecules Adsorbed on Graphite
Authors: Okumura Akihiko , Kazuo Miyamura Kazuo Miyamura , Yohichi Gohshi Yohichi Gohshi
Published: February 2005

The barrier height imaging technique was applied to a graphite surface covered with liquid crystal molecules. Barrier height images of the molecules were found to exhibit better image quality than the scanning tunneling microscope (STM) images. Under different conditions, images of underlying graphite were obtained instead of molecular images, in both STM and barrier height images. It was also found that the barrier height image and the simultaneously obtained STM image of adsorbed molecules were reversed in contrast while those of the underlying substrate graphite were similar. The reason for this difference was discussed in relation to the mechanism of molecular image formation.
Sub-100 nm-Resolution Grazing Incidence Soft X-Ray Microscope with a Laser-Produced Plasma Source
Authors: Aoki Sadao , Ogata Taro , Sudo Shuuzou , Onuki Tetsuji
Published: February 2005

A high-resolution soft X-ray microscope was constructed using grazing incidence mirrors and a laser-produced plasma source. An Nd-YAG pulse laser (1.064 µm) was focused onto an aluminum target to produce soft X-rays above 4 nm in wavelength. The beam energy of the laser was 1.4 J, with a pulse width of 8 ns. The Wolter type-I mirror was used as an objective mirror and the toroidal mirror as a condenser. The magnification of the objective was 20. A holographic plate was used as a detector. Resolution of about 40 nm was achieved with a single shot.
Size Dependence of Morphology of Diamond Surfaces Prepared by DC Arc Plasma Jet Chemical Vapor Deposition
Authors: Hirabayashi Keiji , Kurihara Noriko Iwasaki , Ohtake Naoto , Yoshikawa Masanori
Published: February 2005

The size dependence of the surface morphology of a diamond crystal prepared by the dc arc plasma jet chemical vapor deposition (CVD) is observed using a high-resolution field-emission scanning electron microscope (FE-SEM). The difference in the change of the surface morphology between the {111} surface and the {100} surface is caused by the difference in the growth mode; the {111} surface is formed by the multi-nucleation growth mode, whereas the {100} surface is formed by the single nucleation growth mode.
Magnetooptical Spectra in Pt/Co and Pt/Fe Multilayers
Authors: Sato Katsuaki , Hongu Hidetoshi , Ikekame Hiroshi , Watanabe Jun , Tsuzukiyama Koichi , Togami Yuji , Fujisawa Masami , Fukazawa Tomoyuki
Published: February 2005

Magnetooptical (MO) spectra were measured between 1.2 and 5.9 eV in Pt/Co and Pt/Fe multilayers and corresponding Pt-Co and Pt-Fe alloys produced by DC magnetron sputtering. Real and imaginary parts of off-diagonal conductivity-tensor elements were calculated using optical constants n and k, deduced from the reflectivity spectra measured with synchrotron radiation. The off-diagonal conductivities thus obtained suggest that magnetooptical spectra of multilayers are caused by those of corresponding alloys formed at the interface. To confirm this assumption, a simulation of MO spectra was performed by means of the virtual optical constant method using diagonal and off-diagonal conductivity of the alloy layer determined by the experiment. The results of calculation provide evidence for the presence of an alloy layer at the interface between Pt and transition metal.
Dielectric Relaxation in Oxide Glasses
Authors: Shyamal Kumar Saha Shyamal Kumar Saha , Dipankar Chakravorty Dipankar Chakravorty
Published: February 2005

Dielectric relaxation spectra of lithia-containing silicate glasses and V2O5-P2O5 glasses respectively have been analysed using a heterophase conductor model developed recently. The model considers the glass as comprising diagonal layers of phases having widely different electrical conductivities. The conducting phase is assumed to have a local conductivity varying sinusoidally with the spatial co-ordinate. Excellent agreement between the experimental data and the theoretical values have been obtained over a broad frequency spectrum. The Kohlrausch-Williams-Watts (KWW) exponent has also been estimated for all the glasses. The exponent appears to be related to the conductivity fluctuation-a higher value of the latter leading a lower value of and vice versa.
High Pressure Synthesis of a New Perovskite, (SrLa)(MgMn)O6-x
Authors: Choy Jin-Ho , Demazeau Gérard , Seung-Tae Hong Seung-Tae Hong
Published: February 2005

A new cubic perovskite, (SrLa)(MgMn)O6-x
, has been prepared under the reaction conditions of high temperature (900°C) and high oxygen pressure (60 kbar). The latter condition was generated by in situ thermal decomposition of KClO3 in a belt-type apparatus. The X-ray diffraction pattern shows that Mg and Mn ions are distributed randomly in the B-site of the cubic perovskite with the lattice constants of 3.873(3) Å. Redox titration and thermogravimetric analysis were carried out to determine the average oxidation state of manganese ions, and/or the content of oxygen deficiency that was deduced as x\cong0.38(2). Electron spin resonance spectra and magnetic susceptibility measurements indicate a weak ferromagnetic coupling due to the superexchange interaction between t
2g orbital electrons of Mn(IV) and Mn(V).
Polar Glass Structure for Second-Order Nonlinear Optics Prepared by the Langmuir-Blodgett Method Using Amorphous Polymers with an Azo-Dye
Authors: Okada Shuji , Matsuda Hiro , Masaki Atsushi , Nakanishi Hachiro , Abe Takashi , Ito Hiroshi
Published: February 2005

In order to obtain Langmuir-Blodgett (LB) films for second-order nonlinear optics, LB films of the amorphous copolymers synthesized from methyl methacrylate and 2-(N-ethyl-N-(4-(4-nitrophenyl)azo)phenyl)aminoethyl acrylate were investigated. From the measurement of F-A isotherms and UV and visible spectra of the Langmuir (L) film, it was estimated that the azo-dye moiety was squeezed out from the air-water interface into the subphase, and the dipoles of azo-dye align uniaxially in the direction perpendicular to the interface. The L film could be deposited into X-type multilayers by the horizontal lifting method, resulting in the formation of “polar glass.”
A Semiempirical Calculation of Ion-Induced Kinetic Electron Emission Statistics
Authors: Kaoru Ohya Kaoru Ohya , Ichiro Mori Ichiro Mori
Published: February 2005

Electron emission statistics (ES) of ion-induced electron emission from gold at keV energy are investigated using a Monte Carlo simulation of the transport of the projectile ion and recoiling target atoms and a semiempirical model of the kinetic emission. Apparent deviations of experimental ES from Poisson distributions can be explained to result from backscattering of ions and/or recoiling of target atoms.
Ab Initio Molecular Orbital Study on the Reaction of Trimethylaluminum with an H Radical
Authors: Yoshiko Someya Hiraoka Yoshiko Someya Hiraoka , Masao Mashita Masao Mashita
Published: February 2005

The reaction of trimethylaluminum (Al(CH3)3, TMA) with an H radical has been investigated using ab initio molecular orbital calculations. It has been shown that the reaction energy for Al(CH3)3+H→AlH(CH3)2+CH3 and the activation energy for Al(CH3)3+H→Al(CH3)2+CH4 are much smaller than the dissociation energy for radical decomposition, Al(CH3)3→Al(CH3)2+CH3. This means that H radicals easily break Al-C bonds. Therefore, it is suggested that H radicals, which come from hydride group-V sources, play an important role in the reduction of unintentional carbon incorporation into layers grown from alkyl group-III materials.
Characterization of a Natural Barrier in an Au/Ba1-XKXBiO3 Junction
Authors: Suzuki Seiji , Suzuki Hiroshi , Iyori Masahiro , Takahashi Kazuhiko , Tatsuro Usuki Tatsuro Usuki , Yorinobu Yoshisato Yorinobu Yoshisato
Published: February 2005

X-ray photoelectron spectroscopy (XPS) has revealed that the “natural barrier” on a Ba1-X
K
X
BiO3 (BKBO) thin-film surface is composed of a K-compound layer and a nonstoichiometric layer resulting from Ba depletion. An Au/BKBO junction was fabricated at various temperatures, and its electrical properties were investigated. Junction resistivity could be reproducibly controlled between 10-1 and 10-5 Ω·cm2 by varying the temperature of Au deposition between room temperature (RT) and 300°C. The decrease in junction resistivity with increasing Au-deposition temperature was found to be a result of decomposition of the K-compound layer and rearrangement of the nonstoichiometric layer by annealing the BKBO film.
Fabrication of Superconducting TlSr2(Ca, Cr)Cu2O7 Thin Films by Laser Ablation and Thallium Diffusion
Authors: Tang Yongqiu , Luo Weiang , Chen Zuyao , Nasrazadani Seifollah , Chan Fui T. , Salamo Gregory , Donald O. Pederson Donald O. Pederson , Zhengzhi Sheng Zhengzhi Sheng
Published: February 2005

Superconducting TlSr2(Ca, Cr)Cu2O7 thin films have been prepared on MgO(100) substrates via laser ablation and thallium diffusion. Precursor SrCaCrCuO films were first deposited by an excimer laser; thallium was then incorporated by annealing the precursor films between un-fired TlSrCaCrCuO bulk pellets. The product superconducting films are 1212 phase and exhibit T
c(ρ=0) up to 90 K and J
c(transport) up to 104 A/cm2.
Present and Future Trends in Microlithography
Authors: R. Fabian Pease R. Fabian Pease
Published: February 2005

Some of the trends are well known and are desirable: features are shrinking and field sizes are expanding. At least one other trend is well known and is undesirable: wafer exposure tools are becoming very expensive. Other trends are less clear; throughput and overlay precision are improving but not dramatically. The failure of sub-optical technologies, notably X-ray lithography (XRL), to displace optical lithography is well publicized but at the same time the ability to push optical lithography to feature sizes smaller than the exposing wavelength is becoming tougher; phase-shifting masks and associated approaches (“wavefront engineering”) may be the saviour or may be the “last gasp” of optical lithography. How much further down lithographic technology will be pushed for IC manufacturing may well be set by factors unrelated to the physics of the lithographic process. Such factors include overlay capability, cost effectiveness and the electrical performance of circuit and systems with very small dimensions.
The Method of Measuring Optical Performance in KrF Excimer Lithography
Authors: Suzuki Kazuaki , Yukako Matsumoto Yukako Matsumoto , Masayuki Murayama Masayuki Murayama
Published: February 2005

The theoretical meaning of the ratio of top width to bottom width of a resist pattern (T/B) is explained by a simple model. In KrF excimer lithography, the positive photoresist, FH-EX1, is suitable for T/B evaluation. The method of measuring the optical performance of the projection optical systems using T/B is introduced. The response data of T/B for defocus, dose, the normalized spatial frequency and the illumination/projection condition are shown. In addition, with application of the result of the optimization of the illumination/projection condition by T/B evaluation to the exposure of the chemical amplification resist, it is shown that sufficient depth of focus for 0.35 µm line and space patterns can be obtained.
Fabrication of Diamond Membranes for X-Ray Masks by Hot-Filament Method
Authors: Marumoto Kenji , Yabe Hideki , Matsui Yasuji , Yamashita Hiroaki , Kikuchi Noribumi
Published: February 2005

Diamond thin films have been grown on a Si substrate by a hot-filament method with mixtures of CH4 and H2, and properties such as stress and optical transmittance were investigated for free-standing membrane films as a function of methane concentration (0.5-2.0%) and deposition pressure (8-80 Torr). Ellipsometric and Raman scattering measurements were also carried out to evaluate the film structure, and graphite and void components. It has been found that the loss in the optical transparency is mainly due to light scattering at the surface. It is also shown that boron doping is useful for decreasing the film resistivity, which is advantageous for electron beam (EB) writing and inspections.
Sputtered W-Ti Film for X-Ray Mask Absorber
Authors: Yabe Hideki , Marumoto Kenji , Aya Sunao , Yoshioka Nobuyuki , Fujino Takeshi , Watakabe Yaichiro , Yasuji Matsui Yasuji Matsui
Published: February 2005

Properties of DC-sputtered W-Ti absorber films such as internal stress, density and microstructure were systematically investigated for X-ray mask application. Smooth, stress-free amorphous W-Ti films with a comparatively high density of 16.5-17.0 g/cm3 were obtained by optimizing several conditions: gas pressure, N2 content in the working gas, DC power density and annealing temperature. The reproducibility of the film stress was about ±5×107 Pa. Reproducibility was found to be mainly determined by the degree to which the sputtering tool used could be controlled. Furthermore, it was confirmed that the optimized absorber films offered good stability under stress within 1×107 Pa when stored in an air atmosphere for more than 250 days.
Resolution Limitation of Proximity X-Ray Lithography Determined by Waveguide Effect
Authors: Ogawa Taro , Murayama Seiichi , Kozo Mochiji Kozo Mochiji , Eiji Takeda Eiji Takeda
Published: February 2005

In proximity X-ray lithography, the thickness of mask patterns is 500 to 1000 times greater than the X-ray wavelength. This is expected to induce a new physical phenomenon such as interaction between X-rays within the mask patterns. Taking into account such X-ray wave interaction, the resolution limitation of proximity X-ray lithography is reexamined by a new simulation method treating the mask pattern as a kind of waveguide and directly solving Maxwell's equations, instead of Fresnel's approximation. It is recently discovered that the waveguide effect severely deteriorates the resolution, particularly in the sub-100-nm range, by interference of propagated X-rays in the microgap range. Furthermore, this result makes the mask-wafer gap latitude for pattern replication smaller, and may limit the resolution of proximity X-ray lithography, at most, to 70 nm, which is worse than so far expected. Thus, more attention should be focused on gap control or mask design, taking the waveguide effect into account in order to minimize degradation caused by this effect.
Lissajous Electron Plasma (LEP) Generation for Dry Etching
Authors: Nomura Noboru , Ohkuni Mitsuhiro , Tamaki Tokuhiko , Nakayama Ichiro , Harafuji Kenji , Srinivasan Sivaram Srinivasan Sivaram , Masafumi Kubota Masafumi Kubota
Published: February 2005

A new concept for plasma generation which enhances plasma density at low pressures through the use of a high-frequency rotating electric field is introduced. A 50-MHz electric power was applied to three electrodes which are positioned with a triangular symmetry. A phase shift of 120° between the electrodes brought about uniform and high plasma density at a pressure of 1 Pa. The nonuniformity of Ar gas plasma generated was within 10% over a 6” wafer using a tuned Langmuir probe electron density measurement. Polysilicon etchings were made by both SF6/O2 and Cl2/O2 plasmas. The achieved polysilicon etch-rate was over 200 nm/min for both kinds of plasmas at an electric power of 90 W along with a 13.56 MHz RF bias power of 30 W applied to the substrate. High etch-rate selectivity between polysilicon and oxide of 45 for SF6/O2 and 152 for Cl2/O2 was realized. A very low etch-rate nonuniformity of 1.5% was attained for Cl2/O2.
Study of Pulse Erasing on Phase-Change Erasable (PCE) Sampled Servo Disc
Authors: Ishibashi Hiromichi , Ohta Mitsuro Moriya
Published: February 2005

An experimental study has been conducted on a phase-change erasable (PCE) sampled servo system. In the erase procedure, a pulse-modulated laser beam is irradiated on the PCE media. The result shows that media damage is less than in conventional continuous erasing.
Integrated Optical Pickup with Highly Sensitive Servo Signal Detection
Authors: Yokomori Kiyoshi , FUJita Shunsuke , Misawa Shigeyoshi , Kihara Tami , Aoki Magane , Hiroe Akihiko , Takaura Atsushi , Yoshinobu Nakayama Yoshinobu Nakayama , Hiroyoshi Funato Hiroyoshi Funato
Published: February 2005

We proposed a novel structure for an integrated optical pickup based on monolithic integration of waveguide mirrors and photodetectors in a waveguide on a Si substrate. The detection characteristics of focusing and tracking error signals have been demonstrated to be sufficient for practical applications.
Multilayered Magneto-Optical Disks for Magnetically Induced Superresolution
Authors: Kaneko Masahiko , Katsuhisa Aratani Katsuhisa Aratani , Masumi Ohta Masumi Ohta
Published: February 2005

Magnetically induced superresolution (MSR) has been realized in magneto-optical disks using exchange-coupled magnetic multilayer film. Two new detection methods have been developed. In front aperture detection (FAD), the heated area in the light spot is optically masked. In rear aperture detection (RAD), a signal is read out only from the heated area. For higher readout power in RAD, the aperture area is sandwiched by double masks, since another mask is generated in the highest temperature region. The cut-off spatial frequency in both types of detection is more than two times higher than that in conventional detection. A high C/N of 42 dB is obtained in the MSR disks by both methods for a mark length of 0.3 µm.
High-Density Recording Using Mark Length Recording Method for Magnetooptical Disk
Authors: Toshiaki Iwanaga Toshiaki Iwanaga , Hiroshi Inada Hiroshi Inada
Published: February 2005

Mark length recording for a magnetooptical (MO) disk has two serious problems, thermal interaction and intersymbol interference. In order to resolve these problems, read-write compensation methods, the pulse train write compensation method, readout waveform equalization, and second-order differential pulse detection method, have been developed. Using mark length recording with effective read-write compensation, it has been confirmed that the (1, 7)RLL (Run Length Limited) code is a higher recording code than the (2, 7)RLL code for magnetooptical recording. A 0.5 µm/bit minimum bit recording length, using the (1, 7)RLL code for mark length recording, has also been achieved.
High-Track-Density Flattened Magnetooptical Disks with Low Crosstalk
Authors: Taki Kazunari , Matsuda Riki , Ohashi Yumiko , Takuya Hamaguchi Takuya Hamaguchi , Hideo Maruyama Hideo Maruyama
Published: February 2005

The carrier-to-noise ratio (CNR), crosstalk and noise levels have been investigated for flattened and semiflattened magnetooptical disks with narrow track pitches of 1.2 and 1.0 µm. The track pitch of the flattened and semiflattened disks can be reduced to less than the laser spot size under the condition that the laser spots irradiated on the adjacent recording regions overlap each other only on the spiral guiding band. The CNR of 48.3 dB and low crosstalk of less than -36 dB were achieved for the track pitch of 1.2 µm when the domains of 0.76 µm length were recorded. Crosstalk of less than -30 dB was obtained for the track pitch of 1.0 µm with the conventional optical head having an objective lens of 0.53 NA and a 780-nm laser.
Accurate Track-Count Accessing of Optical Disk Drive
Authors: Masaharu Ogawa Masaharu Ogawa , Osamu Ito Osamu Ito
Published: February 2005

In order to create a rapid accessing feature of optical disk drives, the optical head should be positioned as accurately as possible near the target track if seeking motion is desired. First, an accurate seeking span decision algorithm employed to predict the spiral tracks' rotational number during seeking is discussed. Second, a method of correcting a miscount in the number of crossing tracks for accurate track-count accessing is proposed. During the seeking operation, the method of correcting the track miscount can generate a virtual track-crossing pulse in real time when a track-crossing pulse is missed due to a distorted tracking error signal during seeking. These two methods are practically installed in a 130 mm International Organization for Standardization (ISO) format optical disk drive and effectively operated for accurate track-count accessing.
Static and Dynamic Electron Transport in Resonant-Tunneling Diodes
Authors: Tsuchiya Hideaki , Matsuto Ogawa Matsuto Ogawa , Tanroku Miyoshi Tanroku Miyoshi
Published: February 2005

The static and dynamic behavior of resonant-tunneling diodes is studied using the improved Wigner function model. In the study of static current-voltage characteristics, the exponential decrease of the peak current with the barrier thickness and the existence of a proper barrier thickness for which the peak-to-valley current ratio becomes the maximum are demonstrated. In the large signal simulation, the external current response to an abrupt bias switch is analyzed. As a result, it is found that the switching time of resonant-tunneling diodes is principally determined by the electron effective mass of the material system used rather than by such a device structure as the thickness of the double barrier and the doping density of the electrode.
Direct Solder Bump Formation Technique on Al Pad and Its High Reliability
Authors: Ogashiwa Toshinori , Akimoto Hideyuki , Shigyo Hiroyuki , Murakami Yoshihiro , Inoue Akihisa , Masumoto Tsuyoshi
Published: February 2005

A new technique of direct solder bump formation on an Al pad for flip-chip interconnection was developed by using a rapidly solidified Sn-1Ag-1Zn-5Sb alloy wire. The solder balls made from the wire by arc discharge in Ar containing H2 were bonded to an Al-1Si layer by thermosonic bonding at 423 K in air. The addition of Zn and Sb into the Sn-base alloy was effective in obtaining a good contact state between the ball and the Al-1Si layer. The shear strength of the Sn-base alloy bump is 61 MPa in the as-bonded state and remains almost unchanged even after aging for 400 h at 473 K. The fracture morphology also remains unchanged upon aging. Furthermore, there is no distinct increase in the interdiffusion distance between Sn and Al. These results allow us to expect practical use of the direct solder bump formation technique on Al pad with high reliability.
YBaCuO Thin-Film Growth on Electrooptic LiNbO3 Substrate with Buffer Layer
Authors: Hashiguchi Shoichi , Min Eungi , Sakuta Ken , Kobayashi Takeshi
Published: February 2005

Oxide superconducting YBaCuO thin films were grown on Y- and Z-cut LiNbO3 (LN) electrooptic crystal substrates with and without buffer layers, and their film crystallinity was closely investigated by X-ray diffraction, transmission electron microscopy, reflection high-energy electron diffraction and Auger electron spectroscopy. Due to the intensive reaction, direct deposition of films resulted in poor quality. When sputtered (111)-MgO film was introduced as a buffer layer, significant diffusion of constituent atoms was unavoidable among YBaCuO, MgO and LN. As a result, the superconductivity of the YBaCuO layer was substantially degraded. The Y2O3- stabilized ZrO2 (YSZ) grown by sputtering, followed by wet O2 anneal, served as a good buffer layer for Y1Ba2Cu3O
y
films on LN substrates, and epitaxial growth of (00l)-Y1Ba2Cu3O
y
with T
c0=89 K was reproducibly obtained on Y-cut LN substrates.
Detection of Cell Membranes in Human Corneal Endothelial Micrograms Using Mathematical Morphology
Authors: Hasegawa Akira , Kazuyoshi Itoh Kazuyoshi Itoh , Yoshiki Ichioka Yoshiki Ichioka
Published: February 2005

We propose a method for computer-assisted detection of cell membranes in human corneal endothelial micrograms. Detection of the cell boundary is generally achieved by manually tracing the cell membranes in the micrograms. However, manual tracing is subjective and time consuming. Our method uses modified morphological filters to smooth out noise while keeping linear structures in the image. The processed image is then binarized by template matching. Since the resultant membranes in the image normally consist of broken lines, they must be connected. The identical morphological operation is used again to connect the broken lines. The shapes of cells derived by this method overlap well with those defined by manual tracing.
Optical and Thermal Properties of Sulfur-Perturbed F2
+ Centers in NaCl as the Laser Active Center
Authors: Suzuki Yoshiro , Saitoh Tatsuhiko , Ozawa Ken , Yasuhiro Kondo Yasuhiro Kondo , Masamitsu Hirai Masamitsu Hirai
Published: February 2005

The optimum sample preparation, optical properties, and stability against light and heat for sulfur-perturbed F2
+ centers (F2
+:S-) in NaCl have been investigated to determine the potential quality as a laser material. F2
+:S-'s were introduced into NaCl doped with Na2S by additive coloration and subsequent photoaggregation. Absorption and luminescence bands occurred at 1.18 and 0.832 eV at 80 K, respectively. The excitation spectra for the luminescence showed two maxima at 1.18 and 2.71 eV. The luminescence efficiency was 0.84±0.03 between 80 and 290 K. Photoexcitation of the F2
+ center in F2
+:S- to the 2pπu state at 80 K converted the configuration of F2
+:S- into the most compact form, and also rotated the F2
+ axis by 60°, while the photoexcitation above about 190 K destroyed F2
+:S-. F2
+:S- was expected to be stable for ∼19 days at 290 K, and ∼400 days at 268 K in the dark.
Raman Scattering Spectra of the Folded Acoustic Phonon in AlxGa1-xAs/GaAs Superlattices for Various Al Mole Fractions
Authors: Fukasawa Ryoichi , Okubo Yusei , Ohta Osamu Abe
Published: February 2005

We report the Raman scattering spectra of the folded longitudinal acoustic phonon of Al
x
Ga1-x
As/GaAs superlattices for various aluminium (Al) mole fractions. The effect of Al mole fraction increases on the Raman intensities and the frequencies was studied.
Microwave Studies of Electron Scattering by Isolated Interstitial Oxygen and Oxygen Complex in Silicon
Authors: Ohyama Tyuzi , Sugihara Kohei , Eizo Otsuka Eizo Otsuka
Published: February 2005

Results of microwave cyclotron resonance absorption are given for several Czochralski (CZ)-grown silicon crystals with different concentrations of isolated oxygen atoms. In the same way, results are also presented for some annealed samples with different concentrations of thermal donors (TD) and oxygen-nitrogen (O-N) complexes. We conclude that isolated oxygen atoms, though electrically inactive, contribute to electron scattering. We also give a theoretical prediction based on the electric dipole scattering model with an appropriate effective dipole moment, D=1.1 Debye units, for the Si-O-Si complex. Agreement between theory and experiment is quite satisfactory. In addition, experiments making use of annealed samples enable us to make a precise determination of the electron scattering rates by TD and O-N complexes.
Bond Strength of Bonded SOI Wafers
Authors: Fumitoshi Sugimoto Fumitoshi Sugimoto , Yoshihiro Arimoto Yoshihiro Arimoto
Published: February 2005

We developed a tensile strength measurement technique for bonded silicon-on-insulator (SOI) wafers. After oxidation, wafers are patterned, prior to bonding, to reduce the bonded area. After bonding and grinding, tensile strength is measured by pulling samples perpendicularly to the interface by holders adhesively fixed to the samples. The strength of bonded SOI wafer annealed at 1100°C for 30 minutes exceeded 2000 kgf/cm2, and samples separated not at the bond interface, but at the Si itself. Both SiO2/Si and SiO2/SiO2 bond strengths increased with annealing temperature. The SiO2/Si bond strength was stronger than that of the SiO2/SiO2 bond for annealing temperatures under 1100°C. The strengths became equal after 1200°C annealing. The initial bond strength was maintained in a heat cycle varying from -65°C to 150°C in air for five months.
Analysis of Optical Constants for Sputter-Deposited InSb Films Based on the Interband-Transition Model
Authors: Takayuki Miyazaki Takayuki Miyazaki , Sadao Adachi Sadao Adachi
Published: February 2005

The dielectric-function spectra for InSb films rf-sputter-deposited on (0001) and (011̄0) sapphire substrates have been analyzed by using a simplified interband transition model. The film deposited on (0001) sapphire is epitaxial, while the film on (011̄0) sapphire is polycrystalline in structural properties. The model based on the Kramers-Kronig transformation includes the E
0, E
0+Δ0, E
1, E
1+Δ1, E
0
′, E
0
′+Δ0
′, E
2, E
1
′ gaps and indirect gap (E
g

L
) as the main dispersion mechanisms. The analysis suggests that the sputter-deposited InSb films include a small and a large number of void networks in the film medium for epitaxial and polycrystalline films, respectively. Dielectric-function-related optical constants, such as the refractive index and extinction coefficient, of the InSb films are also presented and analyzed.
A Mass Spectrometric Study of the Decomposition of Trimethylgallium (TMGa) with Trimethylarsine (TMAs)
Authors: Masataka Hoshino Masataka Hoshino
Published: February 2005

Trimethylgallium (TMGa) pyrolysis with Trimethylarsine (TMAs) is studied. I measure the decomposition rate constant by the sampling gas method with a quadrupole mass spectrometer. The decomposition rate constant of TMGa depends on the TMGa initial partial pressure. However, the rate constant of TMGa with TMAs is almost independent of the TMGa initial partial pressure. I propose a model in which TMAs on the reactor surface inhibits the adsorption and decomposition of TMGa on the surface. The TMAs decomposition rate constant increases until TMGa/TMAs=1. It remains constant from 1 to 10. I hypothesize a model for the decomposition of TMGa with TMAs. TMAs molecules adsorb almost all of the adsorption sites. They inhibit the TMGa from adsorption on the sites. TMGa does not decompose on the surface. On the other hand, TMGa catalyzes TMAs to decompose in the gas phase through TMGa·TMAs adducts.
Self-Linearized Optical Modulation of a Normally-On Asymmetric Fabry-Perot Modulator with High Contrast, Low Insertion-Loss, and Low Operating Energy
Authors: Law K.-K. , J. L. Merz J. L. Merz , L. A. Coldren L. A. Coldren
Published: February 2005

We report self-linearized current-biased modulation of a high-performance normally-on asymmetric Fabry-Perot modulator. The self-electro-optic effect device based on this modulator exhibits high contrast (>100:1) reflected output linear with respect to the drive current, large reflectivity change (∼70%) and needs very low electrical switching energy (voltage swing <4 V). Self-linearized modulators with both high-contrast and low insertion loss are potentially useful for sophisticated analog optical processing functions.