bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Series of Bismuth Layer-Structured Ferroelectrics
Authors: Takenaka Tadashi , Gotoh Takahiro , Mutoh Sigeo , Takeshi Sasaki Takeshi Sasaki
Published: October 2002

The general formula of a phase relation between well-known bismuth layer-structured ferroelectrics (BLSF) such as Bi3TiNbO9, Na0.5Bi2.5Nb2O9, Bi4Ti3O12, and Na0.5Bi4.5Ti4O15 including perovskite compounds (Bi0.5Na0.5) TiO3 and NaNbO3, that is, Na(m-3+x)/2 Bi(m+5-x)/2 Ti
m-x
Nb
x
O3m+3 (2≤m≤5), was discussed to form the layer structure with the numbers m=3, 4 and 5 of layer, where x is the number of Nb ions in the layer structure and 1≤x≤2 for m=2 and 0≤x≤m for 3≤m≤5. A new BLSF series is found for m=3 and x=1, 2 and 3. The ferroelectricity for m=4 (x=3 and 4) was very weak and no single phase with m=5 was obtained.
Relaxation Oscillations in PbLa(ZrTi)O 3 Transparent Ceramics
Authors: Zhiming Chen Zhiming Chen , Masatsugu Shibata Masatsugu Shibata , Masatoshi Adachi Masatoshi Adachi , Akira Kawabata Akira Kawabata
Published: October 2002

The relaxation optical oscillation of transparent PbLa(ZrTi)O3 (PLZT) 10/65/35 ceramics in the far field has been observed. This is similar to that observed in Pb(Mg1/3Nb2/3)0.9Ti0.1O3 (PMN) ceramics. However, it is found that the oscillatory shape and the optical power required for oscillation are quite different. The transmitted light intensity at the beam center in the far field I
t(t) has been measured as a function of the laser power and ambient temperature. It is impossible for I
t(t) to reach the region of periodic oscillation. The oscillatory sharp can be described using cos
[∑A(1-e
-t/τ)] which is obtained by consideration of a Fabry-Perotetalon model with temperature change after illumination. The mechanism of the oscillation is discussed.
Grating-Type Optical Deflector Using (Pb, La)(Zr, Ti)O3 Ceramics
Authors: Toshio Utsunomiya Toshio Utsunomiya
Published: October 2002

Various types of deflectors have been proposed to date. Optical deflectors utilizing the electrooptic effect have a simple construction, while the deflection angle is small. However, a deflector with high-speed response as well as random access capability will be required in forthcoming applications. From this point of view, the electrooptic deflector should be reconsidered once again. Therefore, it is required that new materials having larger electrooptic coefficients than the materials we have ever had are discovered and new devices having larger deflection angles than the devices we have ever had are developed. Under these circumstances, we have proposed various types of deflectors: one consists of a (Pb, La)(Zr, Ti)O3 (PLZT) rectangular solid and twin triangular electrodes on its top and bottom surfaces, another consists of a PLZT rectangular solid and three triangular electrodes connected in series on its top and bottom surfaces, and so forth. However, this type of deflector has a defect that the deflection angle is small, and thus the operating voltage is high. To obtain large deflection angle and to realize low-voltage operation, we propose a new type of deflector which consists of a PLZT rectangular solid plate and grating-shaped electrodes on its top and bottom surfaces. Its deflection properties are investigated theoretically and experimentally.
Mode of Occurrence and Cause of Twinning in Lithium Tetraborate Grown by Czochralski Method
Authors: Komatsu Ryuichi , Sugawara Tamotsu , Sugihara Tadashi , Uda Satoshi
Published: October 2002

Mode of occurrence and cause of twinning, which are occasionally observed in lithium tetraborate crystals grown pararell to [110], have been investigated. Twinning is related to the crystal symmetry, i.e., 4-fold screw axis along the c-axis. Relashionship between the cause of striations in crystals and the occurence of twinning during growth has also been examined in connection with temperature fluctuations near the interface.
A Phenomenological Theory of the Ferroelectric Phase Transition of Bi4Ti3O12
Authors: Yoshihiro Ishibashi Yoshihiro Ishibashi
Published: October 2002

The ferroelectric phase transition in Bi4Ti3O12 is interpreted phenomenologically on the basis of a Landau-type free energy. The requirements on the concrete parameter values, necessary to induce the first order tetragonal-monoclinic phase transition in Bi4Ti3O12, are discussed. It turns out that a simple free energy function consisting of six terms in the polarization components p

a
and p

c
reproduces well the phase transition itself and the temperature dependence of spontaneous polarizations, while a seventh term is required to reproduce the temperature dependence of the dielectric susceptibilities.
Deep Electron Traps in n-InP Induced by Plasma Exposure
Authors: Corp. Yoshifumi Sakamoto , Tokyo Tokyo , Japan. Japan. , Koichiro Matsuda Koichiro Matsuda , Junji Shirafuji Junji Shirafuji
Published: October 2002

Deep electron traps in n-InP introduced during helium (He)- or hydrogen ( H2)-plasma exposure have been studied by means of isothermal capacitance transient spectroscopy (ICTS). Two electron traps, (Ec-0.51 eV) and (Ec-0.54 eV), which are designated E2 and E4, respectively, are detected at and near the surface treated with He plasma. These traps induced by He-plasma exposure can be passivated with hydrogen. When the samples are treated with H2plasma, E2 traps are only partly active and E4 traps are not detected due to being totally passivated with hydrogen. The density of E2 traps near the sample surface treated with H2plasma is strongly enhanced by applying reverse bias at room temperature because of dissociation and removal of passivating hydrogen. In contrast, hydrogen-passivated E4 traps become reactivated only by thermal annealing. An isochronal annealing experiment for the He-plasma-treated samples shows the first-order annealing process of E2 traps with the activation energy and the attempt-to-escape frequency of 1.5 eV and 3.2 ×1014s-1, respectively. The thermal dissociation process of hydrogen from E4 traps follows first-order kinetics and its dissociation energy and attempt-to-escape frequency are 1.65 eV and 4.9 ×1013s-1, respectively.
Characterization of Metal/GaAs Interfaces by Monoenergetic Positron Beam
Authors: Uedono Akira , Fujii Satoshi , Moriya Tsuyoshi , Kawano Takao , Shoichiro Tanigawa Shoichiro Tanigawa
Published: October 2002

Defects at Schottky contacts in GaAs devices were probed by a monoenergetic positron beam. Doppler broadening profiles of the annihilation radiation were measured as a function of incident positron energy for a Ti/GaAs specimen. From an analysis of the relationship between theSparameter and incident positron energy, vacancy-type defects were found to be present at the Ti/GaAs interface. Annihilation characteristics of positrons in an AuGeNi/GaAs specimen were also studied. In the alloyed layer, the diffusion length of positrons was decreased by scattering and/or trapping of positrons by precipitates and solute atoms, while no response indicating the presence of vacancy-type defects was observed in Doppler broadening profiles.
Photoluminescence Spectra of Eu2+Centers in Ca(S, Se):Eu and Sr(S, Se):Eu
Authors: Yamashita Nobuhiko , Harada Osamu , Kaizo Nakamura Kaizo Nakamura
Published: October 2002

Photoluminescence and excitation spectra are observed for Ca(S, Se):Eu2+and Sr(S, Se):Eu2+powder phosphors at various temperatures between 4.2 and 300 K. The emission band of Ca(S1-xSex):Eu2+at 300 K shifts almost linearly with an increase inx, from 652 nm (x=0) to 597 nm (x=1). In Sr(S1-xSex):Eu2+, the emission band shifts also linearly from 620 nm (x=0) to 571 nm (x=1). At low temperatures, vibronic structures on emission bands are observed for CaS:Eu2+, CaSe:Eu2+, SrS:Eu2+and SrSe:Eu2+. The excitation processes are attributed to two transitions; the intraionic 4f7→4f65dtransition within Eu2+and the fundamental absorption by host crystal, followed by the transfer of the excitation energy to an unexcited Eu2+ion.
Electrical, Optical and Schottky Properties of AgGa(S1-xSex)2 System
Authors: Hiroaki Matsushita Hiroaki Matsushita , Osamu Shiono Osamu Shiono , Saburo Endo Saburo Endo , Taizo Irie Taizo Irie
Published: October 2002

Crystals of the AgGa(S1-x
Sex)2 system have been prepared by the normal freezing method, and the compositional dependences of the electrical, optical and Schottky properties have been studied. Whereas the compositional dependences of the lattice constants a and c are linear, the optical band gap shows concave decrease. It is found that the electrical resistivity is reduced for all compositions by annealing in vacuum. The Schottky barrier of Al or Au contacts is formed in this system except for AgGaS2. The Schottky properties of annealed samples are much better than those of as-grown samples. The electron affinity of this system is considered to increase linearly with increasing composition x.
In Situ Epitaxial Growth of Superconducting Bi2-Sr2-Can-1-Cun-Oy (n=1, 2) Thin Films by Two-Target Magnetron Sputtering under High Pressure
Authors: Shin-ichi Karimoto Shin-ichi Karimoto , Keiichi Tanabe Keiichi Tanabe , Shugo Kubo Shugo Kubo , Koji Tsuru Koji Tsuru , Minoru Suzuki Minoru Suzuki
Published: October 2002

In situ superconducting thin films of Bi2-Sr2-Ca

n-1
-Cu

n

-O

y

(n=1,2) are grown epitaxially on S
r-T
i-O
3 (100) and MgO (100) substrates by two-target rf magnetron sputtering under a high pressure of 0.5 Torr. During growth, film deposition materials are supplied alternately from Bi2-Sr2-Cu1.3-O

y

and Ca-Cu-O

y

targets to control the number of C
u
O
2 layers. It is demonstrated that a sputtering gas pressure higher than 0.3 Torr effectively reduces the compositional deviation, which is normally caused by the resputtering effect. It is also demonstrated that alternate deposition from the two targets leads to controlled epitaxial growth with the c-axis perpendicular to the substrate. As grown epitaxial films thus prepared exhibit superconductivity at a T
c as high as 79 K for B
i
2-S
r
2-C
a-C
u
2-O

y

films and 8 to 11 K for B
i
2-S
r
2-C
u-O

y

films.
Investigation of Photoresponse in Photoconducting Semiconductor-Superconductor Microstructure
Authors: Takaoka Sadao , Nakao Yukio , Kousai Takamasa , Haruta Kazumasa , Oto Kenichi , Murase Kazuo , Gamo Kenji
Published: October 2002

In order to investigate the influence of light illumination on the superconductivity proximity effect between superconductor and photoconducting semiconductor, we fabricate mesoscopic devices from a pair of Pb, In, Au multilayer superconducting films on indium-doped Pb1-
x

Sn

x

Te (x=0.25) photoconducting semiconductor single crystal. We measure the superconducting characteristic of these devices under illumination. In the devices with the gap length of 0.2-0.3 µ m between a pair of the superconductor films, the hysteresis loop in the current-voltage curve is observed, which is a typical characteristic of the Josephson junction. Furthermore the critical current (the point at which resistance increases rapidly) increases with increasing illumination intensity.
Relaxation Oscillator Using Nb/AlOx/Al/Nb Josephson Junctions Measured with DC Superconducting Quantum Interference Devices
Authors: Shimizu Nobuhiro , Morooka Toshimitsu , Morisue Mititada
Published: October 2002

In this paper we propose a new measurement method to investigate the basic properties of a Josephson relaxation oscillator (RO) using dc superconducting quantum interference devices (SQUIDs). The dc SQUIDs linearly and continuously convert the oscillating current into voltage enabling the waveforms to be clearly observed. The voltage and current waveforms have been measured simultaneously. The basic operation of the RO has been experimentally confirmed.
Thermopower of YBa2Cu3-z(CdS)zO7-δwith z=0-0.8 and Phonon Drag Effect
Authors: Banerjee Souri , Chatterjee Sandip , Barik H. K. , B. K. Chaudhuri B. K. Chaudhuri
Published: October 2002

Positive values of thermopower (S) have been observed for the CdS doped YBa2Cu3-z(CdS)zO7-δ(z=0, 0.05, 0.1, 0.5 and 0.8) oxide superconductors investigated in the temperature range of 80-300 K. In contrast to the behaviour of Zn doped YBa2Cu3-yZnyO7-δsystems we observe a phonon drag peak near the superconducting transition temperatureTc, which is consistently suppressed with the increase of CdS concentrations.
Crystallographic Structure and Magnetic Properties of Co Fine Particles Encaged in Carbon Nanocapsules
Authors: Saito Yahachi , Morio Masuda Morio Masuda
Published: October 2002

Cobalt crystallites wrapped in multilayered graphitic cages (nano-capsules) were produced by an arc discharge method. Structural characterization by X-ray diffraction and transmission electron microscopy revealed that the wrapped cobalt particles were in an fcc phase, with a trace amount of hcp Co. The particles were nominally spherical in shape, and typically 10-100 nm in diameter. The core Co metal was protected against oxidation and coalescence. Temperature dependence of the saturation magnetization (M
s) and the coercive force (H
c) was measured between -200° C and 800° C for powder samples, which revealed that the measured M
s was consistent with that for fcc Co over that temperature range. Magnetic tapes prepared from the present powder exhibited H
c of 250 Oe and 30% remanent magnetization of the M
s at room temperature.
Acceleration of Micromagnetic Calculation Based on LaBonte's Iteration
Authors: Kitti Kosavisutte Kitti Kosavisutte , Nobuo Hayashi Nobuo Hayashi
Published: October 2002

It is confirmed that the relaxation method which was used by LaBonte to calculate the equilibrium magnetization structure iteratively can be accelerated significantly by introducing overrelaxation. The results of two-dimensional calculations made for thin Permalloy films of fixed sizes show that, unlike in the original method, the number of iterations necessary for convergence becomes almost independent of the number of divisions under the optimum conditions for overrelaxation. The result of the calculation made for a cross-tie wall shows that the simulation program based on the impoved LaBonte's method is three times as fast as the program developed previously based on the implicit solution of the Landau-Lifshitz-Gilbert equation. The principle of calculation which was guided on the analogy with the S.O.R. method is presented together with the calculation results.
Soft Mode Dielectric Response and Rotational Viscosity of a Ferroelectric Liquid Crystal Polymer
Authors: Gouda Fathi , Skarp Kent , Andersson Gunnar , Lagerwall Sven T. , Stebler Bengt , Helgee Bertil
Published: October 2002

Using dielectric relaxation spectroscopy, the soft mode rotational viscosity has been determined in the smectic A* phase of a ferroelectric liquid crystal polymer. The dielectric strength and relaxation frequency of the soft mode have been measured in the smectic A* and C* phases in the presence of a bias electric field. The experimental results have been discussed in terms of the Landau free energy expansion of the smectic A* to C* phase transition. The main problems encountered in dielectric measurements in the frequency range 10 Hz to 10 MHz are explained in some detail. It is found that a bias electric field enhances the measurements resolution especially in polymeric system where the conductivity, in this case, is higher than in the low molecular weight compounds.
Proton-Exchanged Waveguides for Surface Acoustic Wave on Z-cut LiNbO3 Using Octanoic Acid
Authors: Cheng Chien-Chuan , Chen Ying-Chung , Wang Sheng-Tz , Bo-Wen Tsai Bo-Wen Tsai
Published: October 2002

The properties of the surface acoustic wave (SAW) on proton-exchanged Z-cut Y-propagation LiNbO3 waveguides using octanoic acid are investigated. The distribution of hydrogen in the PE samples measured by secondary-ion mass spectrometry (SIMS) shows a step like profile with the diffusion constant D
0 and the activation energy Q of about 1.18×106 µ m2/ h and 63.21 kJ/mol, respectively. The results show that the acoustic velocity (V
p) of SAW on PE samples decreases monotonically with increased k
d, where k is the wave number (2π/λ) and d is the waveguide depth. Furthermore, the variation of the electromechanical coupling coefficient (K
2) is similar to that of V
p. The SAW insertion loss (IL) becomes saturated at about k
d=0.13, with a maximum increase of about 5-6 dB.
The temperature coefficient of delay (TCD) calculated from the frequency change of the output of the SAW delay line for the temperature ranging from -10 to 50° C shows a clear increase in the PE layer.
Effect of Mixed Argon and Nitrogen Ion Beam on Cubic Boron Nitride Film Formation in Ion-Beam-Assisted Deposition
Authors: Kawashima Humiyuki , Noriyoshi Shibata Noriyoshi Shibata
Published: October 2002

Cubic boron nitride (c-BN) films have been produced by ion-beam-assisted deposition in which a mixed argon and nitrogen ion beam was irradiated on Si (100) substrates during boron evaporation. Ion species and ion concentrations were measured by mass spectroscopy and optical emission spectroscopy methods. Cubic-BN phase formation was significantly enhanced in a restricted range of Ar+ion concentration of around 30% in the mixed ion beam. At an ion energy range from 0.75 to 1.0 keV, a considerable enhancement was observed with a gas flow ratio of Ar/N2=1/5, which corresponded to a relative Ar+ion concentration of 30%. However, at a gas flow ratio of Ar/N2=1/3, which corresponded to the relative Ar+ion concentration of 50%, no film deposition was observed at 0.75-1.0 keV due to the sputtering effect. It was suggested that the ion bombardment effect on the film crystalline structure is controlled by ion current density, ion mixing ratio and ion energy.
Two Dimensional Structure and Growth Mode of Ultrathin Ce Film on a Mo(110) Surface
Authors: Tanaka Yasuaki , Kamei Masayuki , Yoshihiko Gotoh Yoshihiko Gotoh
Published: October 2002

Adsorbed Ce on a Mo(110) surface was observed by RHEED in order to elucidate the growth mode and the structural change with increasing film thickness. Ce was deposited at room temperature and succeeded by annealing at 800° C under ultrahigh vacuum. The 1st Ce monolayer on Mo(110) surface was composed of a distorted γ-Ce(111) layer. The second Ce monolayer grew on the 1st Ce layer with the structure of γ-Ce(111) with no distortion. Further deposition resulted in growth of isolated 3D crystals on the above mentioned Ce double layers. These facts suggest that Ce grows on Mo(110) surface with Stranski-Krastanov growth mode at high temperature (800° C). The first two monolayers as well as the 3D crystals of Ce grew epitaxially, with the Nishiyama-Wassermann orientational relationship of (111)[11̄0]Ceł(110)[001]Mo.
Discussion on Scanning Tunneling Microscopy Images with Resonant Tunneling Model
Authors: Inaba Hirokazu , Yagi Yoshikazu , Masahiro Okuda Masahiro Okuda
Published: October 2002

We apply a resonant tunneling model to explain various scanning tunneling microscopy (STM) images. The resonant tunneling model is used for determining the negative differential resistance characteristics of current-voltage ( I-V ) and STM images. We calculate the I-V characteristics of the resonant tunneling structure in STM system, and examine the relationship between the I-V characteristics and the anomalous STM images. Our results suggest that the resonant tunneling model can explain the anomalous STM images, for example, a reverse contrast image, and high and low magnification images.
Thermally Stimulated Current Caused by Phase Transition in p-Terphenyl Single Crystals
Authors: Higashino Katsuji , Ishiguro Eiji
Published: October 2002

Thermally stimulated current (TSC) spectra in the absence of optical excitation were measured in the temperature range from 180 to 320 K for p-terphenyl (PT) single crystals exposed to oxygen atmosphere. Two broad TSC peaks in the higher-temperature side above 230 K and a sharp structure near 200 K were observed. The two broad TSC peaks were found to have properties of pyroelectric current which appeared in a reversible manner whenever the sample is cooled and heated. The pyroelectric current is considered to originate from oxygen-PT complexes on the surface of the PT crystal. The origin of the sharp structure was attributed to a change in dielectric constant induced by a phase transition of PT crystal.
Gas Identification by a Single Gas Sensor using Porous Silicon as the Sensitive Material
Authors: Akira Motohashi Akira Motohashi , Manabu Kawakami Manabu Kawakami , Hidekazu Aoyagi Hidekazu Aoyagi , Akira Kinoshita Akira Kinoshita , Akinobu Satou Akinobu Satou
Published: October 2002

The peak frequency of the dielectric loss angle of gas molecules adsorbed in a porous silicon gas sensor having a 2.4 nm pore radius is found to vary inversely proportional to the third power of the gas molecular radius. Peak frequency is extremely sensitive to the pore radius, becoming about one order of magnitude higher for a pore radius of 1 nm. The temperature dependence of the peak frequency in the range of 0 to 25 °C was also determined.
Control of the Arrangement of the Native Gallium Vacancies in Ga2Se3on (100)GaAs by Molecular Beam Epitaxy
Authors: Okamoto Tamotsu , Takegami Tsuyoshi , Yamada Akira , Makoto Konagai Makoto Konagai
Published: October 2002

We attempted to control the arrangement of the native Ga vacancies in Ga2Se3films on (100)GaAs substrates by molecular beam epitaxy. When the GaAs substrates were heat-treated at 550° C before growth, the vacancy-ordered superstructure was formed in the [011̄] direction, which is different from the ordering direction in Ga2Se3on (100)GaP. On the other hand, when the heat treatment was not carried out, the ordering direction was [011] at growth temperatures below 500° C. These results indicate that the initial stage of the growth affects the ordering direction in Ga2Se3on (100)GaAs. We have successfully controlled the ordering direction by introducing a Ga2Se3buffer layer grown at low temperature. Furthermore, we investigated the effects of the growth conditions on the ordering of the Ga vacancies in Ga2Se3films on (100)GaAs, and it was found that the vacancy ordering was highly developed at high VI/III ratio and low growth temperature.
Mössbauer Study of Fe Clusters in Cu Matrices Precipitated from Sputter-Deposited Solid Solution
Authors: Hihara Takehiko , Sumiyama Kenji , Wakoh Kimio , Kenji Suzuki Kenji Suzuki
Published: October 2002

Mössbauer spectra have been investigated for Fe clusters precipitated in a sputter (SP)-deposited nonequilibrium Fe11Cu89alloy, and compared with one produced by cluster beam (CB) deposition. With annealing time of the SP-deposited alloy the number of isolated atoms (monomer) does not change at the first stage, but, the number of small clusters decreases and that of large clusters (γ-Fe) increases. This is attributable to Ostwald ripening. Moreover, the size of Fe clusters is more uniform in the CB-deposited alloy than in the SP-deposited alloy after annealing at 573 K for 98.8 ks.
Atomic Images of Saturated and Unsaturated Fatty Acids at Liquid/Graphite Interface and Difference of Tunneling Currents between Them Observed by Scanning Tunneling Microscopy
Authors: Hibino Masahiro , Sumi Akinori , Ichiro Hatta Ichiro Hatta
Published: October 2002

Structures of arachidic acid and elaidic acid molecules adsorbed onto a graphite substrate were investigated using a scanning tunneling microscope. The ordered arrangements of the molecules were observed with atomic resolution. The image of an arachidic acid molecule is composed of nineteen bright spots at the individual hydrocarbon groups in the alkyl chain and a dark region at the carboxyl group. The image of an elaidic acid molecule with an unsaturated hydrocarbon chain is similar to that of an arachidic acid molecule except for a much brighter spot at the double bond in the hydrocarbon chain. As a result, functional groups such as hydrocarbon chains, carboxyl groups and double bonds could be distinguished by the tunnel currents.
Optical Property of Pb(Zr, Ti)O3 Thin Films Deposited on Transparent Substrates by Atmospheric-Pressure Metal-Organic Chemical Vapor Deposition
Authors: Lee Jong Myeong , Cho Hae Seok , Shin Ju Cheol , Kim Hyeong Joon , Kim Dal-Young , Kwun Sook-Ill
Published: October 2002

Ferroelectric Pb(Zr, Ti)O3 (PZT) thin films were successfully deposited on PbTiO3/ITO/Corning glass and PbTiO3/(100)MgO single-crystal substrates by atmospheric-pressure metal-organic chemical vapor deposition. The PZT thin films deposited at 400° C showed poor optical transparency, while PZT thin films showing high transmittance were deposited above 450° C. The PZT thin films deposited at 500° C showed an optical transparency of 80% and a good quadratic electro-optic effect, of which the coefficient was 1.0×10-18 m2/V2.
Observation of In Growth Modes on Si(111)-√3×√3-Ga Using an Ultrahigh-Vacuum Scanning Electron Microscope
Authors: Naoharu Shimomura Naoharu Shimomura , Toshiro Yamanaka Toshiro Yamanaka , Shozo Ino Shozo Ino
Published: October 2002

Epitaxial growth of In layer on Si(111)-√3×√3-Ga was observed using an ultrahigh-vacuum scanning electron microscope (UHV-SEM). √3×√3-Ga (1/3 ML) and √3×√3-Ga [(1/3+2/3) ML] surfaces were prepared. The latter was formed by deposition of 2/3 ML of Ga on the √3×√3-Ga (1/3 ML) surface at room temperature. After 2 ML of In were deposited on the √3×√3-Ga (1/3 ML) surface, √7×√7 and √3×√3 structures appeared. These structures were clearly observed in the SEM images. Around the steps, ditches were observed. At the In thickness of 6 ML, flat islands with various thicknesses were observed. When 2 ML of In were deposited on the √3×√3-Ga [(1/3+2/3) ML] surface, √3/2×√3/2 structure appeared. All the terraces showed the same number of atomic layers without steps. For further In deposition the terraces had various thicknesses which differed stepwise by one atomic layer.
Effect of Surface Material on Spatiotemporal Structure in O 2 RF Glow Discharge
Authors: Mari Shibata Mari Shibata , Toshiaki Makabe Toshiaki Makabe , Nobuhiko Nakano Nobuhiko Nakano
Published: October 2002

The influence of the electrode material on O2 radio-frequency discharge structure is investigated using the relaxation continuum (RCT) model. The discharges considered in this study are self-sustained between parallel plates with spacing of 2 cm at 13.56 MHz. The spatiotemporal discharge structure for the pressure of 1.0 Torr and the sustaining voltage of 100–300sin
ωt V is calculated. The results are discussed for two types of material differing in the surface recombination probability of atomic oxygen γ. When γ is changed from 0.015 to 0.001, the number density of atomic oxygen increases and the distribution has less spatial dependence. As a result, the rate of the electron detachment caused by the collision between O- and O increases, and the plasma density and the density ratio of the negative to positive ions decrease. The change of the material surface also affects the fluxes of positive ions and atomic oxygens to the electrode at a fixed sustaining voltage. The influence of the surface on the dissipated power is also discussed.
Heat Effect on the Taste of Milk Studied Using a Taste Sensor
Authors: Kiyoshi Toko Kiyoshi Toko , Teru Iyota Teru Iyota , Yasumichi Mizota Yasumichi Mizota , Tetsuya Matsuno Tetsuya Matsuno , Toshihiro Yoshioka Toshihiro Yoshioka , Toyohiko Doi Toyohiko Doi , Satoru Iiyama Satoru Iiyama , Tomihisa Kato Tomihisa Kato , Kaoru Yamafuji Kaoru Yamafuji , Ryozo Watanabe Ryozo Watanabe
Published: October 2002

The effect of heat treatment on the taste of milk was investigated using a taste sensor. The transducer is composed of seven electrodes with different kinds of lipid membranes. Sensory evaluations by humans were made in terms of three taste characteristics of “richness (koku),” “cooked flavor” and “deliciousness” together with a measurement of whey protein denaturation. This study provided a quantitative description of the taste change caused by heat treatment of milk, because the output showed high correlations with richness and the degree of protein denaturation.
Phase Diagram of GaAs (111)B Surface during Metal-Organic Chemical Vapor Deposition Measured by Surface Photo-Absorption
Authors: Nishida Toshio , Uwai Kunihiko , Kobayashi Yasuyuki , Naoki Kobayashi Naoki Kobayashi
Published: October 2002

Using surface photo-absorption (SPA), we have investigated GaAs epitaxial growth on a (111)B substrate grown by metal-organic chemical vapor deposition (MOCVD). From reflectivity trace measurement and a comparison of SPA spectra from an MOCVD-grown surface and an MBE-grown surface, we find fast As desorption in MOCVD growth corresponding to the phase transition from an As-rich (2×2) like structure to a (√ 19×√ 19) like structure, and subsequent slow As desorption corresponding to the phase transition from the (√ 19×√ 19) like structure to a Ga-rich (1×1) like surface. We have also obtained a phase diagram with respect to the transition from the As-rich (2×2) like structure to the (√ 19×√ 19) like structure. Specular morphology and sufficient TMG decomposition in high temperature growth are attributed to partial desorption of As-trimers from As-rich (2×2) like surface.
Photoluminescence of Zincselenide Single Crystals Grown by the Sublimation Method
Authors: Yoshino Kenji
Published: October 2002

Zincselenide (ZnSe) single crystals were grown by the sublimation method with various growth times between 48 and 144 h at 1250° C. Seed crystals were obtained by growth in argon or hydrogen atmosphere for 24 h at 1000° C. The obtained crystals were examined by photoluminescence (PL) measurement at 4.2 K.
The bandgap energy (Eg) decreases in the growth time from 48 to 96 h and increases in the growth time from 96 to 144 h in seed crystals obtained under both atmospheres. These decreases in Eg are due to the increase in the number of Se vacancies in the growth times between 48 and 96 h, and the increase in the number of Zn vacancies in the growth times between 96 and 144 h.
Temperature Dependence in InxGa1-xAs/GaAs Double Quantum Well by Contactless Electroreflectance Spectroscopy
Authors: Su Yan-Kuin , Kuan Hrong , Wu Tien-Shou , Huang Ying-Sheng , Lin Feng-Chuan
Published: October 2002

The contactless electroreflectance (CER) spectra of the double quantum wells InxGa1-xAs/GaAs system have been measured at various temperatures (from 20 K to 300 K). The origins of the various spectra features have been assigned by comparing with an envelope-function calculation taking into account the effects of strain. InxGa1-xAs was grown at 5, 10 and 14% different compositions. Photoluminescence (PL), contactless electroreflectance (CER) and photoreflectance (PR) spectra of the InxGa1-xAs indicates high quality material with narrow full width at half maximum (FWHM) and broadening parameter (Γ) values of the peaks. By varying the temperatures of the samples, the strength of the built-in electric field can be changed by the effect of photo-induced voltages.
Metalorganic Chemical Vapor Deposition of AlGaAs Using Tertiarybuthylarsine
Authors: Ishikawa Hironori , Izumiya Toshihide , Masao Mashita Masao Mashita
Published: October 2002

The amounts of intrinsic carbon incorporation in AlGaAs epilayers grown by metalorganic chemical vapor deposition (MOCVD) were compared between ones grown using AsH3 and ones grown using tertiarybuthylarsine (TBAs). The hole concentration of the epilayers grown using TBAs was much lower than that of the epilayers grown using AsH3. It has been suggested that As2 and/or As4 molecules have the ability to remove methyl groups originating from group-III source materials.
Improved Emitter-Base Junction with In2O3 in Dielectric-Base Transistor
Authors: Hato Tsunehiro , Takauchi Hideki , Yoshida Akira , Tamura Hirotaka , Fujimaki Norio , Oshima Yoshifumi , Naoki Yokoyama Naoki Yokoyama
Published: October 2002

We studied In2O3 for use as an intermediate layer between the YBCO emitter electrode and the SrTiO3 base region of dielectric-base transistors (DBT). We fabricated and tested a YBCO(001)/In2O3(100)/SrTiO3(110) hetero-structure by using a laser-ablation deposition technique with high-density targets. Our YBCO/In2O3/n-SrTiO3 diode structure showed a current density that was one order of magnitude larger than with an MgO intermediate layer.
Precise Angle and Position Detection Utilizing Optical Interference on Metal-Oxide-Semiconductor-Type Position-Sensitive Detectors
Authors: Niu Hirohiko , Shiraishi Takehisa , Yoshida Haruhiko , Matsuda Tetsuro , Seigô Kishino Seigô Kishino
Published: October 2002

The optical interference effect is applied to the previously presented metal-oxide-semiconductor (MOS)-type position-sensitive detector (PSD) to achieve more precise measurements. New interference methods are proposed for the precise measurement of angles and positions, which have been examined by the use of Al-SiO2-Si PSD.
It has been experimentally verified that the PSD is convenient for optical interference to produce periodic output signals indicating half-wavelength displacement. A resolution of one second has been demonstrated for the simple angle-detection system in which only an optical-parallel glass plate is added to the PSD measurement system, and that of 20 nm for the position-detection system of a Michelson-type interferometer incorporated with the PSD.
Effects of Alkaline-Earth Elements on Refractive Index Profile and Domain Inversion of Rb-Exchanged Waveguide in K T i O P O4
Authors: Yamada Noriko , Yukihiro Yamamoto Yukihiro Yamamoto
Published: October 2002

The effects of alkaline-earth elements such as Ca, Sr and Ba on refractive-index profile and domain inversion of a Rb-exchanged waveguide in KTiOPO4have been studied. The waveguide depth estimated from refractive-index profile increased with ion-exchange time in a Rb/Ba-exchanged waveguide, while Rb/Sr- and Rb/Ca-exchanged waveguides showed no difference in the waveguide depth with increasing ion-exchange time of over 15 min. Domain inversion due to the replacement of K by Rb/Sr was demonstrated for the first time through selective etching. In addition, second harmonic generation was observed from a periodically segmented waveguide fabricated by ion exchange of Rb/Sr for K. However, the replacement of K by Rb/Ca did not cause domain inversion.
Superlow-Power Readout Characteristics of Photochromic Memory
Authors: Tsuyoshi Tsujioka Tsuyoshi Tsujioka , Minoru Kume Minoru Kume , Masahiro Irie Masahiro Irie
Published: October 2002

Readout characteristics have been investigated with a superlow-power readout method in order to solve the problem of information destruction caused by repeated readout operations in photon-mode photochromic memories. For ordinary photochromic diarylethene media, it was possible to read signals of about 105–106cycles with this method. This method was also applied successfully to wavelength multiplexed recording.
Effect of Resonant Electrons on Ion Temperature Gradient Mode in Anisotropic Plasma
Authors: Hojo Hitoshi , Katsuragawa Naoki , Nakashima Yousuke , Shoji Mamoru , Mase Atsushi , Itakura Akiyosi , Ichimura Makoto , Inutake Masaaki
Published: October 2002

The effect of resonant electrons on the ion temperature gradient mode in an anisotropic plasma is studied. From the analysis of the growth rate and the stability boundary, it is shown that the resonant electron leads to the suppression of the mode due to Landau damping.
Optical Image Simulator Using the Real-Space Expression of the Object Pattern and a Differential Operator for Optical Proximity Effect Estimation
Authors: Harada Katsuhiro , Takeuchi Yoshinobu , Horiuchi Toshiyuki , Seitaro Matsuo Seitaro Matsuo
Published: October 2002

The new optical image simulator described here can accurately estimate the optical proximity effect that causes pattern distortion in systems using off-axis illumination or oblique illumination and in systems using phase-shifting masks. To prevent an undesirable proximity effect from being influenced by the repeated object pattern that occurs in simulations using the conventional fast Fourier transform (FFT) routine, we calculate the image intensity using the real-space expression of the object pattern. A differential operator and Taylor series expansion are introduced to accelerate the calculation. The simulation results are compared here with those of a commercially available FFT simulator, and this comparison confirms that the new simulator evaluates the proximity effect correctly and that the FFT simulator can produce incorrect image intensity at the circumference of the object pattern. We also show that the differential operator and Taylor series expansion are effective in speeding up the optical image calculation using the real space expression.
Arterial Blood Flow Through a Nonsymmetrical Stenosis with Applications
Authors: Vijai P. Srivastava Vijai P. Srivastava
Published: October 2002

The problem of blood flow through an axially nonsymmetric but radially symmetric stenosed tube when blood is represented by a Casson fluid and a Newtonian fluid, is investigated. The equations governing the flow obtained from the proposed model are solved and closed-form expressions for blood flow characteristics, namely, the dimensionless resistance to flow, the wall shear stress and the shearing stress on the wall at the maximum height of the stenosis, are derived. The results obtained are discussed in brief both qualitatively and quantitatively by comparing with related studies in the literature. It is shown that the resistance to flow decreases with increasing values of the parameter determining the stenosis shape and that the maximum resistance is attained in the case of symmetric stenosis. The magnitudes of the resistance to flow are always higher in the case of a Casson fluid model than in the case of a Newtonian fluid model. The wall shear stress and the shearing stress on the wall at the maximum height of the stenosis possess a character similar to the resistance to flow with respect to the Casson fluid parameter; however, the latter is independent of the stenosis shape and the former posseses a character different from the resistance to flow with respect to the parameter determining the stenosis shape. The analysis results are finally used to estimate the blood flow characteristics in different blood vessels using the numerical data from literature.
Practical Optical Proximity Effect Correction Adopting Process Latitude Consideration
Authors: Tsudaka Keisuke , Kawahira Hiroichi , Sugawara Minoru , Ohnuma Hidetoshi , Tomita Manabu , Satoru Nozawa Satoru Nozawa
Published: October 2002

For an optical lithography process with a design rule of under 0.35 µ m, printed resist pattern size and shape tend to differ from those designed because of the optical proximity effect, resulting in line width error and corner rounding. In order to solve such problems, a new optical proximity effect correction (OPC) system taking account of the resist development and process latitude has been developed. The system is designed focussing on accurate optimization of cell patterns such as memory or gate array devices. Using this OPC for a memory device cell pattern of 3.5×6.3 µ m area, the resist edge placement error with process conditions of within ±5% exposure latitude and ±0.75 µ m depth of focus achieved was one-third of that without OPC.
The calculation time for this correction is as short as 2 minutes on a 135 MIPS workstation even with the resist development and process latitude consideration.
Electron Beam Writing Techniques for Fabricating Highly Accurate X-Ray Masks
Authors: Kise Koji , Aya Sunao , Yabe Hideki , Marumoto Kenji , Hifumi Takasi , Yasuji Matsui Yasuji Matsui
Published: October 2002

The problems in electron beam writing for the membrane-process were investigated; the resist thickness on the thinned membrane was adequately uniform (3σ=0.44%), and the resultant pattern size error was negligible. Deformation due to mask chucking onto the electron beam (EB) cassette was small enough to allow production of acceptable gigabit ULSI devices. We also confirmed that the SiC membrane is durable enough for the task of membrane-process, even with thermal impact of EB energy 40 times larger than that used in conventional writing. Moreover, the improvement of pattern size accuracy by using multiple writing was investigated in detail under various conditions of the beam step size, the writing time and the resist sensitivity. The pattern width deviation was improved from 20% to 13% for 0.15 µ m line-and-space patterns by multiple writing, and was little dependent on the beam step size and the resist sensitivity.
Monolayer Nitrogen-Atom Distributions in Ultrathin Gate Dielectrics by Low-Temperature Low-Thermal-Budget Processing
Authors: Lucovsky Gerald , Lee David R. , Hattangady Sunil V. , Niimi Hiro , Jing Ze , Parker Chris , Hauser John R.
Published: October 2002

The research reported in this paper is based on an approach to low-temperature/low-thermal budget device fabrication that combines plasma and rapid thermal processing, and which has been customized to control separately i) the N-atom bonding chemistry and composition profiles, and ii) the structural and chemical relaxations in stacked gate structures. Control of N-atom incorporation at the monolayer level at the crystalline- and polycrystalline-Si interfaces, and at alloy levels within the bulk dielectrics has been achieved by combining low-temperature (∼300° C) plasma-assisted processes to generate the N-atom concentration profiles, with low-thermal-budget rapid thermal annealing (RTA) to promote chemical and structural relaxations that minimize defects and defect precursors. Device measurements indicate that N-atom incorporation improves reliability with respect to hot carrier degradation of field effect transistors.
Fabrication of Lateral Tunnel Junctions and Measurement of Coulomb Blockade Effects
Authors: Wolfram Langheinrich Wolfram Langheinrich , Haroon Ahmed Haroon Ahmed
Published: October 2002

In order to operate single-electron devices at high temperatures, a fabrication process for laterally arranged double tunnel junctions is presented. The dimensions of the island can be reduced relatively easily down to the resolution limit of lithography, resulting in extremely low capacitances. The basic idea of the fabrication process is a very thin metallic nanowire which is made discontinuous by means of a sharp-edged groove in the substrate. Tunnel junctions are formed at either edge of the groove, and the tunnel barrier gap can be adjusted via the depth of the groove and the deposition parameters of the metal film. Coulomb blockade was observable, which is persistent up to temperatures above 77 K.
CONCAVE-DMOSFET: A New Super-Low On-Resistance Power MOSFET
Authors: Tokura Norihito , Yamamoto Tsuyoshi , Kataoka Mitsuhiro , Takahashi Shigeki , Kunihiko Hara Kunihiko Hara
Published: October 2002

This paper describes a new super-low on-resistance power MOSFET.
The new transistor “CONCAVE-DMOSFET” has a concave channel structure fabricated not by trench etching technique, but by a combination of local oxidation of silicon (LOCOS) and diffusion self-alignment using oxide film as a double diffusion mask. The CONCAVE-DMOSFET based on 16 µ m cell design has been fabricated for the first time, and the specific on-resistance of 75 mΩ· mm2 with breakdown voltage of 50 V has been achieved. This specific on-resistance is the lowest ever reported for power MOSFETs of comparable same design rule. The lowest value has been realized by means of the CONCAVE-DMOS technology, which eliminates JFET resistance and provides a damage-free concave surface resulting in high channel mobility of 300 cm2/V·s.
Application of As-Deposited Poly-Crystalline Silicon Films to Low Temperature CMOS Thin Film Transistors
Authors: Miyasaka Mitsutoshi , Komatsu Tadakazu , Shimodaira Akemi , Yudasaka Ichio , Hiroyuki Ohshima Hiroyuki Ohshima
Published: October 2002

As-deposited poly-crystalline silicon (poly-Si) films have been applied to low temperature processed complementary metal oxide semiconductor (CMOS) thin film transistors (TFTs). Continuous two-step deposition of poly-Si films in the infra-low pressure chemical vapor deposition (ILPCVD) reduces the silane partial pressure to 0.10 mTorr to obtain high quality films. The maximum processing temperature of 555° C through the CMOS TFT fabrication is during the poly-Si deposition. Since the as-deposited poly-Si films are good in quality, CMOS static shift registers have been successfully integrated on a glass substrate with the as-deposited poly-Si TFTs.
Melt State of Bi2SrxCa3-xCu2Oz with 1.5<x<2.3 in 0.01 atm Oxygen Partial Pressure
Authors: Yoshida Masashi
Published: October 2002

The phase evolution in the melt of Bi2Sr

x

Ca3-
x

Cu2O

z

has been investigated in 0.01 atm oxygen environment. It has been found that a 4-phase equilibrium is achieved among Bi2(Sr, Ca)3O6, (Sr, Ca)CuO2, (Sr, Ca)2CuO3 and liquid in the region 1.8<x<2.1 at 850° C. On the other hand, for x=2.3, Bi2(Sr, Ca)3O6 and (Sr, Ca)CuO2 are present as solid phases, while for x=1.8, Bi2(Sr, Ca)3O6 and (Sr, Ca)2CuO3, and for x=1.6, only (Sr, Ca)2CuO3 is present. In the entire range of x, the liquid phase has a characteristic composition of Bi:(Sr+Ca)=1:1 while the content of Cu changes as x changes. The solidification of the Bi2212 phase proceeds below 840° C. The Sr/Ca ratio of the 2212 phase grown from the melt is found to be nearly equal to that of the starting material. As temperature decreases, Cu content in the liquid decreases while the ratio of Bi:(Sr+Ca) remains at 1:1.
A Fluorescence Method for Two-Dimensional Quantitative Detection of Organic Residues on Printed Wiring Boards
Authors: Takesue Hiroto , Ikuta Yuji , Shigeki Hoshino Shigeki Hoshino
Published: October 2002

Organic residues which remain on printed wiring boards (PWBs) even after washing with chlorofluorocarbon substitutes are excited optically and their quantities are estimated with significant accuracy on the basis of their fluorescence. The thickness of residues is related linearly to the intensity of their fluorescence and can be estimated even for very thin layers. The distribution of residues on PWBs is visualized as a two-dimensional map of fluorescence intensity, in which variations in intensity are represented as variations in color. This proposed estimation method is applied here to an examination of the relationship between flux residues and electromigration on PWBs, as well as to an estimation of the effectiveness of washing with trichloroethane substitutes.
Growth of Nitrogen-Doped ZnSe and Inhibition of Hydrogen Passivation of Nitrogen Acceptor by Photoassisted Metal-Organic Chemical Vapor Deposition
Authors: Fujita Yasuhisa , Terada Toshiyuki , Tetsuya Suzuki Tetsuya Suzuki
Published: October 2002

Growth of nitrogen doped ZnSe was carried out at the growth temperature of 330 to 390° C by photoassisted metal-organic chemical vapor deposition (MOCVD). Nitrogen concentration of more than 1018 cm-3 was obtained at growth temperatures lower than 350° C using ammonia and t-butylamine as nitrogen dopant sources. Furthermore, hydrogen passivation of nitrogen, which is regarded as a possible cause of acceptor compensation in the layer doped using ammonia, was drastically decreased and p-type layer with hole concentration of 8.3×1017 cm-3 was obtained using t-butylamine.
Raman Study of Ring Structures of Chemical Vapor Deposited SiO 2 Thin Films
Authors: Tadashi Nakano Tadashi Nakano , Naomi Mura Naomi Mura , Akihiko Tsuzumitani Akihiko Tsuzumitani
Published: October 2002

Raman spectroscopy was applied to the analysis of SiO2 thin films formed by various chemical vapor deposition (CVD) methods. Different sizes of siloxane ring structure were successfully detected in the CVD films. The intensity of the Raman scattering band attributable to the three-membered ring (R
3) was found to be a characteristic feature of the film. The deposition method as well as its conditions apparently affected the ratio of the intensity of the R
3 band to that of the R
4 band. From consideration of the etching rate measurement, it is suggested that the R
3 structure can be regarded as a kind of defect of the siloxane network. The constitution of the ring structures given by the Raman spectroscopy is probably a useful indicator of the properties of CVD SiO2 dielectric films.