bluuebunny/crossref_metadata_2025 huggingface dataset:
Indium-Tin Oxide Thin Films Prepared by Chemical Vapor Deposition from Metal Acetates
Authors: Maruyama Toshiro , Tabata Kenji
Published: February 2005

Transparent conductive indium-tin oxide thin films were prepared by a low-temperature atmospheric-pressure chemical vapor deposition method without using an oxygen donor. The raw materials were indium acetate and tin diacetate, which are inexpensive and easy to handle. A 260-nm-thick polycrystalline film was obtained after 1 hour of deposition at a reaction temperature of 300°C. The resistivity was 6.93×1013 Ω·cm, and the transmittance was more than 90% in most of the visible range (450–700 nm).
Effects of Oxygen-Potential-Controlled Annealing on the Superconducting Properties of (Bi, Pb)2Sr2Ca2Cu3Oy Thin Films
Authors: Hattori Hisao , Nakamura Keikichi , Ogawa Keiichi
Published: February 2005

The oxygen potential of thin films consisting of monophasic (Bi, Pb)2Sr2Ca2Cu3O
y
was controlled by annealing them under various oxygen partial pressures. The T
c of (Bi, Pb)2Sr2Ca2Cu3O
y
was found to decrease monotonously with decreasing oxygen potential. However, T
c did not change when annealed under higher oxygen pressure up to 2.9×104 torr. The carrier concentration was found to change with oxygen partial pressure, implying that oxygen supplies the carrier. An optimum range of the carrier concentration exists for attaining the highest T
c. This finding is consistent with those of other high T
c hole-type superconductors.
Transport Properties of Parallel Multiple Ballistic Point Contacts
Authors: Hirayama Yoshiro , Saku Tadashi
Published: February 2005

Parallel multiple ballistic point contacts are fabricated using the highly resistive region induced by focused Ga ion beam scanning. The fabricated structure is controlled by a single Schottky gate electrode placed upon it. Quantized currents of µA order are obtained in the fabricated structures.
The Pseudospark Switch–A High-Voltage Gas Discharge Switch for High-Power Applications
Authors: Tinschmann Axel , Okumura Tsuyoshi , Taniwaki Manabu
Published: February 2005

A pseudospark switch, which can substitute thyratrons in pulsed power applications, was successfully tested at hold-off voltages up to 25 kV and peak currents up to 18 kA. A lifetime test was performed until 3.6×107 shots, without showing any significant degradation of the switch. Current rise rates up to 6×1011 A/s and a current reversal capability of 100% are additional features of this switch, which can help to improve the performance of pulsed power devices.
X-Ray Orientation Topography
Authors: Chikaura Yoshinori , Takata Yoshihiro
Published: February 2005

In order to observe orientation distribution in a single crystal, X-ray orientation topography has been devised by applying X-ray scattering radiography. A single crystal of iron-3%(wt)silicon alloy was examined to demonstrate the capability of the system. An accuracy of 20 arc seconds has been attained by the present apparatus with a spatial resolution of less than 48 µm.
Atomically Resolved STM/STS Observation on the Edge of CuO2 and (BiO)2 Layers of Bi-Sr-Ca-Cu-O
Authors: Hasegawa Tetsuya , Kitazawa Koichi
Published: February 2005

Atomic resolution STM observation of the layered structure of an oxide superconductor has been achieved for the first time. The relative contributions to the electronic states from the CuO2 and (BiO)2 layers were remarkably different depending on the tunneling bias voltage, reflecting the two-dimensional nature of the electronic structure of Bi2Sr2CaCu2O
y
. STS on each layer indicated the (BiO)2 layer to be insulating with an energy gap of 0.1 eV while the CuO2 layer was found to be essentially metallic but with an anomalous low-lying excitation spectrum. The modulation structure was observed on the layer-edge surface as well as on the basal plane.
Hydrogen Extraction Activation Energy from D2
+-Implanted Magnetic Bubble Garnet
Authors: Furuya Keiichi , Suzuki Hisamitsu , Kikuchi Tadashi , Uematsu Kenichi , Shin Jae Soo , Imura Ryo
Published: February 2005

Deuterium in D2
+-implanted magnetic garnet films was extracted by means of thermal desorption mass spectrometry and found to be a form of D2O at 360°C in vacuo. The overall activation energy for extraction was measured as 1.62 eV for D2O and 1.04 eV for DHO. The effect of the SiO2 overlayer was also discussed.
Water-Adsorbed States on Silicon and Silicon Oxide Surfaces Analyzed by using Heavy Water
Authors: Yabumoto Norikuni , Minegishi Kazushige , Komine Yukio , Saito Kazuyuki
Published: February 2005

Water-adsorbed states on Si, native oxide and thermal oxide surfaces are investigated by means of thermal desorption spectroscopy. D2O is used to detect the water signals from these surfaces, which are separated from background H2O signals. The water desorption is 1/10 less than the hydrogen desorption. The amount of hydrogen adsorbed is largest on the Si surface and smallest on the thermal oxide surface. Four types of binding states of hydrogen are assigned to be SiO-H and Si-H on the silicon surface, Si-H in the native oxide, and Si-H in the interface between the native oxide and the silicon substrate.
Energetics in Structure Transformation of Ir Clusters on the Ir Surfaces
Authors: Chen Chonglin , Tsong Tien T.
Published: February 2005

We report a quantitative study of the energetics in one- to two-dimensional structure transformation of 3-atom Ir atomic clusters on Ir surfaces. On the (111) plane, the temperature dependence of the ratio of the probabilities of observing a 1-D and a 2-D structure exhibits a simple linear Arrhenius behavior. The 2-D structure is more stable and the difference in the cluster binding energies is 0.098±0.004 eV. In contrast, on the (001) plane, the 1-D structure is more stable, and the energy difference is 0.335±0.015 eV. In addition, a significant deviation from the simple linear Arrhenius behavior is found at low temperatures.
Anomalous Corrugation Height of Atomically Resolved AFM Images of a Graphite Surface
Authors: Sugawara Yasuhiro , Ishizaka Tatsuya , Morita Seizo , Imai Syozo , Mikoshiba Nobuo
Published: February 2005

To clarify the origin of the anomalous corrugation height of atomically resolved AFM images of graphite under strong repulsive (contact) force, we carefully investigated the variation of the force between the lever and a graphite surface during lateral scans. For a weak repulsive force (∼1.3×10-7 N), the variation of the force was rather smooth, where the deduced corrugation heights were ∼0.2 Å. On the other hand, for a strong repulsive force (∼2.2×10-6 N), the variation of the force was spikelike, where the maximum corrugation heights of ∼1.7 Å were determined. We also found that the direction of the spikelike force modulation depends on the scanning direction of the sample. Observed variation of the force seems to be evidence that this anomalous large corrugation height of ∼1.7 Å is induced by the stick slip motion between the lever and a graphite surface.
Spatial Distribution of SiH3 Radicals in RF Silane Plasma
Authors: Itabashi Naoshi , Nishiwaki Nobuki , Magane Mitsuo , Naito Susumu , Goto Toshio , Matsuda Akihisa , Yamada Chikashi , Hirota Eizi
Published: February 2005

Infrared diode laser absorption spectroscopy (IRLAS) was applied to the measurement of SiH3 in a RF silane P-CVD chamber with parallel plate electrodes. The spatial distribution of SiH3 radicals between the electrodes was measured to obtain the incident flux density of SiH3 to the electrode surface. The growth rate of a-Si:H was also measured in the same plasma. These data were used to estimate the contribution of SiH3 to a-Si:H thin-film growth.
Observation of a 0.055 nm Spacing Lattice Image in Gold using a Field Emission Electron Microscope
Authors: Kawasaki Takeshi , Matsuda Tsuyoshi , Endo Junji , Tonomura Akira
Published: February 2005

A 350 kV electron microscope equipped with a magnetic-field-superimposed field emission gun has been developed. A 0.055 nm-spacing lattice image in a gold thin film has been successfully observed with this electron microscope under the condition of 300 kV electron accelerating voltage.
Experimental Fabrication of XMOS Transistors Using Lateral Solid-Phase Epitaxy of CVD Silicon Films
Authors: Ishii Kenichi , Hayashi Yutaka , Sekigawa Toshihiro
Published: February 2005

Experimental fabrication of an XMOS transistor which has two insulated gates called upper-gate and lower-gate has been performed using lateral solid-phase epitaxy of a-Si film deposited by CVD of SiH4. The fabricated XMOS transistors exhibited no punch-through effect and good controllability of the upper-gate threshold voltage by the voltage applied to the lower-gate. It was found that the measured values of the slopes on the upper-gate threshold voltage control by the lower-gate voltage showed good agreement with the calculated value of the slope derived from a simple capacitance couple model.
Electrical, Magnetic and Superconducting Properties of the Quenched Bi2Sr2Ca1-xNdxCu2O8+δ System
Authors: Koyama Kuniyuki , Kanno Satoshi , Noguchi Seiichiro
Published: February 2005

Structure, resistivity and susceptibility are studied in the quenched Bi2Sr2Ca1-x
Nd
x
Cu2O8+δ system. The quenched samples with 0≦x≦1 have a single phase of the Bi2Sr2CaCu2O8+δ structure, as do the furnace-cooled samples. The oxygen concentration decreases slightly by about 0.05 upon quenching from 800°C to liquid nitrogen temperature. The T
c remains a constant (∼90 K) for x≦0.15, and decreases linearly with x for 0.15≦x≦0.45, and superconductivity disappears in the samples with x≧0.45. Referring to the previous results for the furnace-cooled Bi2Sr2Ca1-x
Nd
x
Cu2O8+δ system, the relationship between the T
c and the hole concentration in [Cu-O] is confirmed to be universal in both the quenched and the furnace-cooled Bi2Sr2Ca1-x
Nd
x
Cu2O8+δ systems.
AsH3 Pre-Exposure Conditions for GaAs Epitaxial Growth on Si by Melalorganic Chemical Vapor Deposition
Authors: Fujita Kazuhisa , Shiba Yasunari , Yamamoto Toshiro
Published: February 2005

The effects of AsH3 pre-exposure at high temperature on the crystalline quality of GaAs layer grown on Si have been studied using X-ray diffraction. The full width at half-maximum (FWHM) of the (400) reflection from the GaAs layer was affected by the pressure; at 100O°C, the sample with the AsH3 pre-exposure at 76 Torr shows narrower FWHM than that with the pre-exposure at 760 Torr. Both samples are analyzed by SIMS. The concentration profile of As and Si around the interface in the sample with lower pressure is sharper than that in the sample with higher pressure.
Effects of Annealing on the Structural Properties of GaAs on Si(100) Grown at a Low Temperature by Migration-Enhanced Epitaxy
Authors: Nozawa Kazuhiko , Horikoshi Yoshiji
Published: February 2005

This paper reports the effects of annealing on the structural properties of GaAs on Si(100) grown at a low temperature by migration-enhanced epitaxy (MEE). Low-temperature MEE growth at 300°C followed by brief postgrowth annealing at 580°C produces better-quality crystals than conventional high-temperature growth. A 6 µm-thick sample produced using this method showed an X-ray diffraction FWHM of 123 arcsec with an etch-pit density of 4×105 cm-2. This indicates that low-temperature MEE growth can significantly reduce the dislocation density in the GaAs epilayer compared to the conventional two-step growth technique.
Valence Band Offsets of the InxGa1-xAs/GaAs Strained-Layer Superlattice
Authors: Shiraishi Kenji , Ohno Takahisa
Published: February 2005

This paper presents a theoretical study of the valence band offset of the In
x
Ga1-x
As/GaAs strained-layer superlattices by the ab initio pseudopotential method on the basis of local density functional formalism (LDF). The strain of the superlattice is determined by the valence force field method (VFF), and the spin-orbit interaction is included a posteriori. In these superlattices, heavy holes and light holes are confined in the In
x
Ga1-x
As and GaAs layers, respectively. Also studied is the conduction band offset ratio, which is almost indepdent of the In content x.
Silver-Enhanced Synthesis of YBa2Cu3O7-x
Authors: Wu Nae-Lih , Chang Ying-Chih
Published: February 2005

Formation of the high-T
c superconducting oxide YBa2Cu3O7-x
via Y2BaCuO5+3BaCuO2+2CuO →2YBa2Cu3O7-x
was found to be greatly accelerated by silver (Ag). As an example, for calcination at 900°C for 1 h, the fractional conversion was almost tripled with an addition of 2% (by weight) Ag in the reactant powders. Furthermore, for the calcined powders showing similar extents of the reaction, both the Meissner effect and T
c (up to 95 K) increased with the Ag content. DTA studies established that the temperature at which the maximum reaction rate occurred was significantly lowered due to the presence of Ag.
Orientation of CaCuO2 Thin Films in RF Sputtering
Authors: Yazawa Ichiro , Terada Norio , Matsutani Katsuhiro , Sugise Ryoji , Jo Masatoshi , Ihara Hideo
Published: February 2005

The orientation of CaCuO2 films was examined under various RF sputtering conditions. Two types of crystal growth, (001) and (110) orientation, were controlled by varying the partial pressure of O2 and Ar gas. (001) orientation was observed at lower gas pressure and (110) orientation was observed at higher gas pressure. This suggests that the orientation of CaCuO2 film is related to the total pressure of the sputtering gas.
Application of In-Beam Perturbed Angular Distribution to the Study of High-Tc Oxides
Authors: Komori Fumio , Katsumoto Shingo , Kobayashi Shun-ichi , Ikehata Seiichiro , Ikeda Nobuo , Hashimoto Osamu , Fukuda Tomokazu , Nomura Toru , Yamazaki Toshimitsu
Published: February 2005

The time differential perturbed angular distribution method was applied to the study of high-T
c oxides. Spin rotation signals of the 19F isomer ( τ=128 ns) produced from oxygen nuclei via 16O( α, p)19F were observed in various high-T
c oxides above T
c. The internal field was determined with an accuracy of about 1%. This method is an alternative to the 17O-substituted NMR.
As-Grown Crystallized Thin Films on Bi(Pb)-Sr-Ca-Cu-O by Single-Target Magnetron Sputtering
Authors: Hakuraku Yoshinori , Higo Satoru , Miyagi Daisaku , Ogushi Tetsuya
Published: February 2005

As-grown crystallized superconducting thin films of Bi(Pb)-Sr-Ca-Cu-O have been prepared on MgO(100) at 620–720°C by dc magnetron sputtering using a single target. The targets used were Bi
x
Pb1Sr2Ca2.2Cu3O
y
(x=2.0 and 2.5) in nominal composition. The obtained films had a smooth surface and exhibited a high degree of c-axis orientation perpendicular to the substrate. The c-axis lattice constant of the films was controlled to the values of about 24, 31, 37 and 43 Å by changing the substrate temperature, respectively. As a result, the superconducting properties of the films were strongly affected by the substrate temperatures during film growth. These results also showed that the films with different c-axis lattice constants (i.e., different numbers of CuO2 planes) were easily prepared by a simple single-target sputtering.
Tunneling Characteristics of YBaCuO/MgO/Pb Planar Tunnel Junctions and Observation of Josephson Effect
Authors: Iguchi Ienari , Furuyama Masafumi , Kusumori Takeshi , Shirai Koji , Tomura Shoji , Nasu Masako , Ohtake Hiroaki
Published: February 2005

The measurements on reproducible YBa2Cu3O
y
(YBCO)/MgO/Pb planar tunnel junctions by an in situ fabrication technique are reported. A thin MgO (1.8–6.0 nm) is used as an insulating barrier. The observed tunnel characteristics exhibit a gap opening structure around 20 mV and the zero bias anomaly, similar to those of YBCO/MgO/Au tunnel junctions as previously reported. For junctions with low tunnel resistance, Josephson current is observed. Josephson critical current against external magnetic field exhibits a Fraunhofer-like pattern. Shapiro steps are also observed under microwave irradiation.
Giant Magnetoresistance of Fe/Cr Multilayers on MgO(100) and Glass Substrates
Authors: Araki Satoru , Shinjo Teruya
Published: February 2005

Multilayers consisting of thin Fe and Cr layers were prepared on MgO(100) and glass substrates by alternate deposition in ultrahigh vacuum. It is confirmed that the giant magnetoresistive change found by Baibich et al. in Fe/Cr multilayers on GaAs(100) substrates is reproduced in both types of samples. The resistivity of the Fe(27 Å)/Cr(12 Å) multilayer on MgO is reduced by 37% by applying 7 kOe at 77 K and 13% at 300 K. A sample on a glass substrate also shows a resistivity change of 27% with 7 kOe at 77 K.
Hybrid Optical Bistability and Limiting in Ferroelectric Liquid Crystals
Authors: Ozaki Masanori , Hatai Takashi , Yoshino Katsumi
Published: February 2005

Hybrid optical bistability and limiting in ferroelectric liquid crystals with linear feedback has been studied. Optical limiting and bistability are observed for the cases of negative and positive feedback parameters, respectively. It is also found that the hysteresis in the transmission-voltage curve of ferroelectric liquid crystal contributes to the expansion of the bistable region.
Surface Potential of Polyimide Langmuir-Blodgett Films Deposited on Metal Electrodes
Authors: Iwamoto Mitsumasa , Fukuda Atsushi
Published: February 2005

The surface potential of multilayers of polyimide (PI) deposited on base-Au, Cr and Al electrodes was measured by the conventional surface potential technique. A comparison was made between the surface potential of clean base electrodes and that of base electrodes onto which various numbers of layers were deposited. The surface potential of PI depends strongly on the material of the base electrodes. It was suggested that the surface potential of PI multilayers originates from charges displaced from base electrodes to the PI multilayers.
The Observation of Half Splayed States in Ferroelectric Liquid Crystal Filled Cells by the Excitation of Optic Modes
Authors: Elston S. J. , Sambles J. R.
Published: February 2005

Splayed states in ferroelectric liquid crystal (FLC) cells are seen in general if the elastic distortion energy involved is less than the surface polar interaction energy. Here such states are examined by the propagation of optic modes along a thin layer of FLC. This allows the examination of the optic tensor configuration and indicates the existence of a pinned point at the chevron interface in the smectic layering. This leads to the direct observation that in a chevron type cell these are actually half splayed states, where one half of the cell is uniform, and the other half is splayed. It is seen that the splayed part can be switched between the two halves of the cell.
Investigation of the Decomposition Process of Ga Organometals in MOCVD by the Surface Photo-Absorption Method
Authors: Makimoto Toshiki , Yamauchi Yoshiharu , Kobayashi Naoki , Horikoshi Yoshiji
Published: February 2005

Surface photo-absorption (SPA) is a newly developed in situ optical monitoring technique for the epitaxial growth process. This method is based on the measurement of reflection intensity of p-polarized incident light at close to the Brewster angle. This letter describes use of SPA to investigate the decomposition of Ga organometals in metalorganic chemical vapor deposition during the growth of GaAs layers. Triethylgallium and trimethylgallium are used as the gallium sources, and the temperature range is 300°C–670°C. It is found that the SPA signal is very sensitive to chemical species on the growing surface, and that triethylgallium decomposes almost completely on the growisng surface above 500°C while trimethylgallium does not completely decompose even at 630°C. The results imply that the self-limiting characteristic of the growth rate in atomic layer epitaxy is caused by the formation of a molecular layer of methylgallium compounds.
Electron Paramagnetic Center in Neutron-Irradiated AlN
Authors: Honda Makoto , Atobe Kozo , Fukuoka Noboru , Okada Moritami , Nakagawa Masuo
Published: February 2005

Neutron-Irradiated AlN was investigated using electron paramagnetic resonance. The broad spectrum arising from the electrons trapped in N3- vacancies can be explained by the hyperfine interaction with the surrounding 27Al nuclei. The obtained parameters, the g-value and the hyperfine constant are g=2.007±0.001 and A=(10.9±0.5)×10-4 cm-1, respectively.
Heating Current Induced Conversion between 2×1 and 1×2 Domains at Vicinal (001) Si Surfaces–Can it be Explained by Electromigration of Si Adatoms?
Authors: Stoyanov S.
Published: February 2005

Besides randomly walking on the crystal surface the adatoms are assumed to have a drift velocity c=D
s
F/k
T, where D
s is the surface diffusion coefficient and F is a force, related in some way to the specimen heating current. In the limiting case of narrow terraces (small interstep distance l) the major process on the whole surface is the surface transport, which results an absence of noticeable conversion of the domain structure when F
l/k
T≈0.1. Making use of the agreement between this conclusion and the experimentally observed [H. Kahata and K. Yagi: Jpn. J. Appl. Phys. 28 (1989) L858] lack of conversion (under reversal of the current direction) at l≈40–80 nm and T=700°C, the force F is estimated to be in the range 10-14–10-13 N. Experimental verification of the predicted stability of vicinal surfaces with l<80 nm when F has step-up direction and instability (decay to large terraces, separated by steps of multiple height) when F has step-down direction can be a crucial test of the hypothesis for an electromigration of Si adatoms.
Cold Nuclear Fusion Induced by Controlled Out-Diffusion of Deuterons in Palladium
Authors: Yamaguchi Eiichi , Nishioka Takashi
Published: February 2005

A gigantic neutron burst of (1-2)×106 n/s has been detected from deuterated Pd plates with heterostructures set in a vacuum chamber. An explosive release of D2 gas, biaxial bending of all the samples, and excess heat evolution were also observed at the same time. It has been concluded that these phenomena are caused by the cooperative production of D accumulation layers at Pd surfaces due to controlled out-diffusion of D-atoms.
Optical Ionization Energy of Shallow Donors in S-Doped Epitaxial GaAs
Authors: Saito Ken , Yamada Syoji
Published: February 2005

Far-infrared (FIR) laser experiments together with secondary-ion mass spectrometry (SIMS) analysis are performed to study the shallow donor-ionization energy in n-type GaAs with high donor concentrations. It is shown that the optical ionization energy of shallow donors remains constant for donor concentration N
d as high as 2.0×1016/cm3 and decreases gradually to zero at N
d,crit.∼1×1017/cm3. The latter value is larger than that from the Mott criterion for a metal-insulator transition or that of the thermal regime.
Correlation between Fermi Level Stabilization Positions and Maximum Free Carrier Concentrations in III–V Compound Semiconductors
Authors: Tokumitsu Eisuke
Published: February 2005

Maximum carrier concentrations reported in the literature are compared with the respective Fermi level stabilization positions for various semiconductors. It is shown that heavy n-type (p-type) doping is obtainable for a semiconductor whose Fermi level stabilization position is located near the conduction (valence) band edge.
Oxygen Control in Bi2Sr2Ca1Cu2Ox Superconducting Thin Films by Activated Oxygens
Authors: Takeuchi Kou , Kawasaki Masashi , Yoshimoto Mamoru , Saito Yasutoshi , Koinuma Hideomi
Published: February 2005

Activated oxygens were generated by various methods to compare their effect on the control of oxygen stoichiometry in Bi2Sr2Ca1Cu2O
x
superconducting thin films. The treatment of a film with an oxygen plasma or ozone at 400°C decreased the T
c onset of the film by as much as 20 K from untreated film as it was in the case of film treatment in atmospheric oxygen under UV light irradiation. On the other hand, films exposed to UV light irradiation in the presence of N2O (400 Torr) increased their T
c onset to 100 K by about 20 K. These T
c changes accompanied the change in the c-axis lattice constant. The lattice of the specimens with T
c onset of 60 K was smaller than that of the untreated films, while the specimens with T
c onset of about 100 K had a stretched c-lattice. Thus, the oxygen content or hole concentration in Bi2Sr2Ca1Cu2O
x
films can be controlled at a relatively low temperature and its effect is reflected in the changes of lattice constant and T
c.
Spectral Dependence of Optical Reflection during Flow-Rate Modulation Epitaxy of GaAs by the Surface Photo-Absorption Method
Authors: Kobayashi Naoki , Horikoshi Yoshiji
Published: February 2005

Surface photo-absorption (SPA) is a newly developed in situ optical monitoring technique for the epitaxial growth process. This method is based on the reflectivity measurement of p-polarized incident light at the Brewster angle. This configuration minimizes the bulk GaAs contribution in light reflection. The small reflection light intensity change in the growing process is thus detected with a high signal-to-noise ratio. The spectral dependence of the SPA signal during flow-rate modulation epitaxy of GaAs was found to be composed of anisotropic and isotropic wavelength regions which correspond to the absorption spectra of surface chemical species. These spectra can be ascribed to the optical absorption of the chemical bond between surface Ga (or As) atom and underlying As (or Ga) plane with anisotropy and the optical absorption of the chemical bond related to the surface Ga atom, which is perpendicular to the (001) surface.
Photochemical Etching of GaAs using Synchrotron Radiation
Authors: Terakado Shingo , Nishino Jun-ichi , Morigami Mitsuaki , Harada Mitsuaki , Suzuki Shigeo , Tanaka Kenichiro , Chikawa Jun-ichi
Published: February 2005

The photochemical etching of gallium arsenide by chlorine was investigated using synchrotron radiation. At the substrate temperatures above 25°C, both the irradiated and nonirradiated regions were uniformly etched. In case of substrate temperatures below -25°C, highly selective etching was observed in the irradiated region. We considered that at low temperatures, etching reaction caused by gas-phase excitation is suppressed and photochemical surface reaction becomes dominant.
Molecular Beam Epitaxial Growth of ZnSSe with Hg-Xe Lamp Irradiation
Authors: Matsumura Nobuo , Tsubokura Mitsutaka , Miyagawa Kazuhiro , Nakamura Nobuhiro , Miyanagi Yoichi , Fukada Takashi , Saraie Junji
Published: February 2005

ZnSSe epilayers were grown by MBE with light irradiation using a Hg-Xe lamp. The free-exciton-emission intensities increased in the photoluminescence spectra of the light-irradiated epilayers, and the sulfur composition also increased. However, the surface morphologies were rough. The irradiated-photon-energy dependence of the above irradiation effects was investigated for the first time, and it turned out that the photons of energy larger than the band-gap energy of the epilayer were responsible for the light-irradiation effects.
Thermal Analysis of Target Surface in the Ba-Y-Cu-O Film Preparation by Laser Ablation Method
Authors: Otsubo Shigeru , Minamikawa Toshiharu , Yonezawa Yasuto , Morimoto Akiharu , Shimizu Tatsuo
Published: February 2005

For clarifying the mechanism of material removal from the surface of Ba-Y-Cu-O by a high-intensity pulsed laser beam, a transient temperature distribution was calculated, and the obtained results were compared with the experimental ones. The calculated values well explain the experimental results such as a threshold of the Ba-Y-Cu-O evaporation. It was found that the subsurface temperature exceeds the front surface temperature. Under such conditions, an explosive removal of material can occur resulting in very rapid material removal with no compositional deviation between the target and the deposited film.
Stress-Induced Contact Failures in Al-Si/n-Si Structures
Authors: Mayumi Shuichi , Shishino Masahumi , Ueda Seiji
Published: February 2005

Al-Si/n-Si contacts passivated with P-SiN films were electrically opened during an accelerating life test at 150°C, while contacts passivated with PSG films or P-SiO films were not. The failure rate increased as the size of contacts decreased and also as the tensile stress in Al-Si interconnections increased. The open failures at contacts were attributable to Si precipitation at contacts from Al-Si in the course of stress relaxation in the interconnections.
Effect of Ba-Doping on the Superconductivity of Bi(Pb)-Sr-Ca-Cu-O
Authors: Hakuraku Yoshinori , Ohara Masahiro , Sumiyoshi Fumio , Ogushi Tetsuya
Published: February 2005

We have prepared Ba-doped Bi(Pb)-Sr-Ca-Cu-O superconductor by a solid-state reaction. The sample compositions used were Bi1.84Pb0.34Sr1.91-x
Ba
x
Ca2.03Cu3.06O
y
with different Ba content of x=0, 0.1 and 0.2, respectively. After calcination followed by presintering, the samples were sintered in air at 820–860°C for 50 h. The superconducting property of the obtained samples was greatly affected by doped-Ba content and the sintering temperature. The X-ray diffraction showed the growth of an almost-single phase with a high-T
c superconducting phase. The crystal quality improved, but the temperatures with the superconducting transition were noticeably suppressed by Ba-doping. The c-axis lattice constant slightly increased with Ba-doping. This fact indicated that Ba was probably incorporated into the Sr site of the crystal structure.
Fabrication of RF-Sputtered Y-Ba-Cu-O-Ag Composite Thin Films
Authors: Hahn T. S. , Lee Sang Young , Kim Y. H. , Choi S. S. , Park S. J.
Published: February 2005

We report the successful fabrication of Y-Ba-Cu-O-Ag composite thin films using a single-target RF-sputtering method. Y-Ba-Cu-O grains of the composite film are mostly between 1000 Å and 2000 Å, less than one-tenth the grain size of a typical postannealed polycrystalline Y-Ba-Cu-O film, revealing that the composite film may be useful in fabricating microstrip lines. Zero-resistance temperatures (T
c's) of two Y-Ba-Cu-O-Ag thin films having 1.2 weight% and 6.4 weight% silver are 64 K and 53 K, respectively, which are lower than the T
c's of our Y-Ba-Cu-O thin films prepared without silver.
The Effects of Active Oxygen Atoms in Y-Ba-Cu-O Sputtering
Authors: Matsubara Gensoh , Okabe Yoichi
Published: February 2005

The role of active oxygen atoms in the as-grown fabrication of Y-Ba-Cu-O superconducting thin films on a MgO single-crystal substrate was investigated. By producing different active oxygen concentrations at the substrate using the UV-ozone technique, we found that the role of active oxygen atoms is not only to promote oxidation but also to lower the film growth temperature. As a result, as-grown superconducting Y-Ba-Cu-O thin films were fabricated at the film growth temperature of above 500°C by the UV-ozone technique with reactive ac sputtering.
Multispiral Pregrooved Disk Fabricated by a Beam Scanning Method
Authors: Miyagi Masami , Yamazaki Hiroki , Fujimori Susumu , Iwasawa Akira , Funakoshi Nobuhiro
Published: February 2005

A multispiral pregrooved disk has been fabricated by the beam scanning method. In this method, a recording laser beam is scanned by a galvanomirror to trace the multispiral subcircle while the disk continuously moves. It is demonstrated that a 1.6-micron-spacing 6-fold spiral pregroove is recordable by this method. This method achieves a precise track pitch with less than 0.04-micron deviation. Stable tracking operation on the multispiral pregroove and multibeam recording on the 3-fold spiral pregroove were performed.
Dielectric Relaxation Study of Polychlorotrifluoroethylene by Thermal Sampling TSDC Method
Authors: Shimizu Hiroshi , Nakayama Kazuo
Published: February 2005

The dielectric constant ( ε'), dielectric loss factor ( ε''), and dielectric loss tangent ( tan
δ) of polychlorotrifluoroethylene were calculated using the relaxation parameters derived from the thermal sampling TSDC analysis. Numerical results of dielectric data were represented by three-dimensional (3-D) and/or two-dimensional (2-D) spectra and were compared with the available experimental data. The progression of ε'' in a simulated 3-D spectrum revealed that the incorporation of two γ relaxation modes ( γa and γc) occurred near 1 Hz resulting in the formation of a single peak.
Amorphous Ar Produced by Vapour Deposition
Authors: Kouchi Akira , Kuroda Toshio
Published: February 2005

Amorphous thin film of Ar has been produced for the first time by the vapour deposition method at 10 K and at a condensation rate of less than 3×10-11 m ·s-1 in ultrahigh vacuum. The electron diffraction pattern shows a diffuse halo, and the vapour pressure is two orders of magnitude larger than that of fcc Ar. The crystallization temperature of a-Ar is 20±1 K.
A Novel Method of Sputter Deposition Utilizing a Hot-Cathode Penning Ion Source
Authors: Shoji Fumiya , Oura Kenjiro
Published: February 2005

A new-type ion source based on characteristics of Penning discharge has been devised for sputter deposition. A hot cathode was axially integrated, resulting in high-density plasma at a pressure of lower than 1×10-3 Torr. Sputter deposition could be performed at a low acceleration voltage of 0.20 kV. Plasma parameters, i.e., anode voltage, filament power, and gas pressure, could be independently changed, enabling us to control the deposition process precisely.
Preferential PtSi Formation in Thermal Reaction between Pt and Si0.8Ge0.2 MBE Layers
Authors: Kanaya Hiroyuki , Cho Yukiko , Hasegawa Fumio , Yamaka Eiso
Published: February 2005

Thermal reactions between Pt and Si0.8Ge0.2 MBE layers were studied by sputtering AES and X-ray diffraction measurements. Pt(1000 A)/Si0.8Ge0.2(1000 A) annealed at 300°C for 3 hours or at 400°C for 1 hour formed Pt2(Si0.8Ge0.2)1 or Pt1(Si0.8Ge0.2)1, respectively. The sample annealed at 400°C for 16 hours showed a slight accumulation of Ge at the Pt(SiGe)/Si interface, and the annealing at 500°C for 1 hour repelled the Ge from the surface Pt(SiGe) layer to form a Ge-rich SiGe epitaxial layer at the PtSi/Si interface. These results suggest a stronger bonding of Pt-Si than Pt-Ge and a possible preferential formation of PtSi at the interface even for lower annealing temperatures.
Stress Distribution Analysis in Structured GaAs Layers Fabricated on Si Substrates
Authors: Sakai Shiro , Kawasaki Koji , Wada Naoki
Published: February 2005

The thermal stress in GaAs on Si produced by the thermal expansion coefficient mismatch is analyzed by the finite element method. It is shown that the stress is released near wafer edge or in the mesa-etched stripe whose width is the same order or narrower than the GaAs thickness. The calculated results are compared with the published data to show the validity of the analysis. The new structure to lower the stress is proposed and analyzed. More than one order of magnitude reduction can be obtained by partially separating the GaAs layer from the substrate.
Adsorption and Oxidation Species on a-SiC:H Surface by Corona Exposure
Authors: Kodama Jun , Araki Shin , Kimura Masatoshi , Inagaki Takefumi
Published: February 2005

The hydrogenated amorphous silicon (a-Si:H) photoreceptor used in printing systems produces image blurring at high temperature and humidity. We have examined the problem using infrared reflective-absorption spectroscopy (IR-RAS). We exposed a hydrogenated amorphous silicon carbide (a-SiC:H) film to a corona discharge at 35°C and 80% RH. Adsorption and oxidation species on the film can be detected and determined by IR-RAS. NO3
-, CO3
2-, Si-OH, H-OH, and Si-O-Si are detectable in the a-SiC:H film. The amount of them increases with corona exposure time. We clarify that these specids in a-SiC:H film cause the contact angles to decrease with the corona exposure time and blur the image.
Hot-Pressing of Bi-Pb-Sr-Ca-Cu-O Superconducting Thick Film
Authors: Murayama Norimitsu , Hiramatsu Yasuji , Torii Yasuyoshi
Published: February 2005

Screen-printed Bi1.84Pb0.34Sr2.03Ca1.9Cu3.06O
y
superconducting thick films were prepared on MgO substrates from powder consisting almost entirely of the 110 K phase, and the thick film sandwiched between the two MgO substrates was further hot-pressed in air. Under the hot-pressing condition of 500 kg/cm2 at 855°C for 30 min, the T
c and resistivity at 270 K were 105 K and 6.1×10-4 Ω·cm, respectively. The J
c was 4800 A/cm2 at 77 K in zero magnetic field. The relationship between superconducting properties and hot-pressing conditions was examined.
Fiber-Optic Separation and Compression of Gain-Switched Multimode Semiconductor Laser Pulses
Authors: Lee Yong-Tak , Takahashi Ryo , Kamiya Takeshi
Published: February 2005

Separation and compression of pulses from a gain-switched multimode semiconductor laser are achieved by using a dispersion-shifted fiber. The evolution of the pulse waveform is analyzed by an improved expression of diode laser chirp, suitable for large signal modulation. A brief discussion is made on the possible application of this technique to a novel hybrid time/wavelength division multiplexing scheme for fiber-optic signal transmission.
Initial Magnetization and Critical Current Density for Sintered YBCO and BSCCO Superconductors
Authors: Uehara Kouichi , Yamada Nobuya , Matsumoto Mitsuhiro , Nagano Saburou , Kaji Gentarou
Published: February 2005

The initial Magnetization curves in low-magnetic field were measured for sintered polycrystalline samples of YBa2Cu3O
y
and Bi1.84Pb0.34Sr1.91Ca2.03Cu3.05O
y
. These measurements reveal that transport critical current density (J
ct) is determined by the coupling strength of grain boundaries against penetration of the magnetic flux. This analysis provides a useful method of estimating the J
ct values for sintered oxide superconductors.
Phase Diagram of Nd2-xCexO3-CuO Systems
Authors: Oka Kunihiko , Unoki Hiromi
Published: February 2005

A phase diagram of the Nd2-x
Ce
x
O3-CuO system was investigated in preparation for the crystal growth of Nd2-x
Ce
x
CuO4. Differential thermal analysis measurements of Nd2-x
Ce
x
CuO4 were performed in N2, Ar/O2, air and O2 atmosphere.
Orthorhombic-Tetragonal Phase Boundary in the LnBa2Cu3Oy Compound Systems (Ln=Tm, Gd, Sm)
Authors: Kogachi Mineo , Nakahigashi Kiyotaka , Minamigawa Shinnosuke , Nakanishi Shigemitsu
Published: February 2005

The orthorhombic-tetragonal phase boundaries were determined for TmBa2Cu3O
y
(TBC), GdBa2Cu3O
y
(GBC) and SmBa2Cu3O
y
(SBC) by means of high temperature (in situ) X-ray diffaction. To cover the wide temperature and compositin regions, two different methods previously reported in YBa2Cu3O
y
(YBC) were employed. The results obtained for the TBC, GBC and SBC revealed the same characteristic in shape as that in the YBC: the phase boundary consisted of two curves being upwardly convex. The Rietveld refinement of phases appearing on the low temperature side was also made for the samples with various y's obtained by long-period annealing at low temperature. The percolation limit was confirmed to be located at the position proposed previously for these systems.
Preparation of Bi-System Superconducting Thick Films by Melt Quenching Method
Authors: Emoto Takahito , Yamamoto Jyunya , Murakami Yoshishige
Published: February 2005

We have succeeded in obtaining a Bi-system superconducting thick film on a MgO(100) substrate. It consists mainly of the high-T
c phase and exhibits T
c(zero) at 102 K by the melt guenching method with an intermediate process. The process uses precursor powders which already contained high-T
c superconducting phase.
Effects of Heat Treatment Conditions on the Critical Current Densities of Ba2YCu3O7-y Films Prepared by the Dipping-Pyrolysis Process
Authors: Kumagai Toshiya , Manabe Takaaki , Kondo Wakichi , Minamiue Hidehiro , Mizuta Susumu
Published: February 2005

The effects of temperature and atmosphere on the BYCO formation reaction of BaCO3, Y2O3 and CuO, prepared by the pyrolysis of metal acetylacetonate solution, were examined by TG-DTA, XRD and resistivity measurement. This reaction was found to proceed readily below 900°C under low oxygen partial pressures. Superconducting Ba2YCu3O7-y
films with T
c,zero\cong90 K and J
c(77 K)=300–400 A/cm2 were prepared by the dipping-pyrolysis process using the above solution through heat treatments at 820°–880°C under controlled low oxygen partial pressures of ρ(O2)=1×10-3–2×10-4 atm followed by O2 annealing.
Effects of Film Thickness and Annealing Conditions on 2223 Phase Growth in BSCCO Films Produced by Pb Vapor Doping
Authors: Hayakawa Hirotoshi , Nakamura Keikichi , Ikeda Shozo , Ogawa Keiichi , Takahashi Satoshi
Published: February 2005

The conditions for increasing the fraction of the 2223 phase in BiSrCaCuO films in the Pb vapor doping method were investigated. The optimum range for the growth of the 2223 phase was determined as a function of annealing condition and film thickness. It is shown that the annealing at 835°C for 5 to 12 h after 850°C×3 h annealing in Pb atmosphere is most effective in obtaining the impurity-free 2223 phase. The fraction of the 2223 phase thus obtained exceeded 99%.
Y-Ba-Cu-O Superconducting Films with High Jc Values by MOCVD using Ba-Addition Products
Authors: Matsuno Shigeru , Uchikawa Fusaoki , Yoshizaki Kiyoshi
Published: February 2005

Y-Ba-Cu-O superconducting films having high J
c of 6.3×106 A/cm2 at 77 K and T
c of 92 K were prepared by metalorganic chemical vapor deposition using a new transport technique with Ba-addition products. This CVD method could realize stable vaporization and smooth transportation of Ba source material due to the increase of the evaporation rate at low sublimation temperatures. Consequently, good reproducibility for preparation of the high J
c films (over 106 A/cm2) was achieved.
GaAs/AlGaAs GRIN-SCH-SQW DBR Laser Diodes with Passive Waveguides Integrated by Compositional Disordering of the Quantum Well Using Ion Implantation
Authors: Hirata Takaaki , Maeda Minoru , Suehiro Masayuki , Hosomatsu Haruo
Published: February 2005

GaAs/AlGaAs GRIN-SCH-SQW DBR laser diodes are fabricated by ion implantation and two-step MOVPE growth. Passive waveguides are monolithically integrated by compositional disordering of quantum well heterostructures using silicon ion implantation. Waveguide losses of partially disordered GRIN-SCH-SQW passive waveguides are measured, and propagation losses as low as 4.4 cm-1 are observed at the lasing wavelength. Stable single mode operation is obtained, and the narrowest linewidth achieved is 840 kHz. The results show that this fabrication process is useful for photonic integrated circuits.
Anomalously Large Shift of Absorption Edge of GaSe-Based Layered Crystal by Applied Electric Field
Authors: Iwamura Yasuo , Moriyama Makoto , Watanabe Naozo
Published: February 2005

GaSe and related layered crystals were grown by the Bridgman method. Thin samples were obtained by cleaving. Transmission spectra of the thin samples were measured under an electric field with both incident direction and field direction parallel to the c-axis. The absorption edge shifted forward longer wavelength by 20 nm under an electric field of as low as 1 kV/cm. The shift is more than two orders larger than evaluated on the Franz-Keldysh mechanism.
Enhancement of Faraday Effect in Highly Ce-Substituted YIG Epitaxial Films by RF Sputtering
Authors: Gomi Manabu , Furuyama Hiroshi , Abe Masanori
Published: February 2005

Faraday rotation and ellipticity spectra were measured at photon energy h
v=0.9–4.0 eV for films of Y2Ce1Fe5O12 and Y3Fe5O12 epitaxially grown by rf sputtering. The Ce substitution prominently enhances Faraday effect with paramagnetic dispersion relation not only in the IR region (centered at h
v≃1.4 eV) but also in the UV region (centered at h
v≃3.1 eV). The enhancements in the IR and UV regions are nearly equal in magnitude but opposite in sign. Thus the magneto-optical enhancement by Ce in garnet can be ascribed to two electronic transitions centered around 1.4 and 3.1 eV.
Learning Effect in the Doping Process of Conducting Polymer
Authors: Yoshino Katsumi , Kuwabara Takao , Kawai Tsuyoshi
Published: February 2005

The doping process of poly(3-alkylthiophene) has been activated by repeating the doping-undoping process as a learning effect in neural networks. The diffusion coefficient of a chemically prepared poly(3-alkylthiophene) film increases markedly with doping-undoping cycles. These effects are discussed in terms of the change in morphology of polymer films.
Phase Diagram of the CuGaS2-In Pseudobinary System
Authors: Miyake Hideto , Sugiyama Koichi
Published: February 2005

The phase diagram of the CuGaS2-In pseudobinary system has been investigated. In solutions saturated with stoichiometric CuGaS2 solute at temperatures above 1020°C are single phase, but those saturated below 1020°C are separated into two liquid phases: sulfur-excess primary and sulfur-deficient secondary phases. The solid in equilibrium with the In solution is ascertained to be a single-phase CuGa
x
In1-x
S2 chalcopyrite alloy at temperatures above 70O°C. The mole fraction of CuInS2 in the CuGa
x
In1-x
S2 alloy was determined as a function of liquidus composition of the In solution.
Role of Space Charge in a Memory-Type Organic Photoreceptor Coated on an Organic Polymer Electrode
Authors: Nakazawa Yusuke , Hoshino Katsuyoshi , Jun-ichi Hanna Jun-ichi Hanna , Hiroshi Kokado Hiroshi Kokado
Published: February 2005

Role of photo-generated space charges on the memory effect, observed in an iodine-doped conductive polymer / poly(N-vinylcarbazole) (PVK)-trinitrofluorenone (TNF) double-layered system, was investigated by means off voltage-current measurements. The results were consistent with the previous conclusion obtained by the xerographic technique. The memory effect was found to come from space charges formed at the electrode-photoreceptor interface containing iodine. The space charge formation induced apparent barrier height lowering against carrier injection and the magnitude of lowering was about 60 meV. It was also found that injected charges from polymer electrode per unit space charge was more than 2×103.
Light-Scattering Characteristics in Smectic A Liquid Crystals
Authors: Nobuhiko Nawa Nobuhiko Nawa , Dau Nuo Dau Nuo
Published: February 2005

The light-scattering characteristics of smectic A liquid crystals are investigated. In the case of an electrooptic effect, the scattering texture is produced through either the field effect or the current effect. It is found that the textures formed due to this effect give rise to diffusive scattering patterns resulting from multiple scattering in the structure. In the case of a thermooptic effect, the scattering texture is obtained through the phase transition from a nematic to a smectic A phase. The textures formed as a result of the thermooptic effect exhibit higher diffraction peaks correlating to the shape of the domains. The scattering characteristics are found to depend on the process which forms the textures.
Small Angle X-Ray Scattering from Kr Bubbles in Amorphous and Crystallized Ni84Y8Kr8
Authors: Ratag Victor M. , Satoshi Sakai Satoshi Sakai , Nobuyoshi Wakabayashi Nobuyoshi Wakabayashi
Published: February 2005

Amorphous and crystallized Ni84Y8Kr8 samples have been examined by the small angle X-ray scattering technique. The size of Kr bubbles in the amorphous sample was estimated to be about 20 Å. The size increased with increasing annealing temperature and annealing time.
Symmetry and Second-Order Susceptibility of Hemicyanine Monolayer Studied by Surface Second-Harmonic Generation
Authors: Kajikawa Kotaro , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: February 2005

Theoretical expressions for the surface second-harmonic generation are given for some particular combinations of polarizers. Simulated results are displayed and are compared with the experiments made for the hemicyanine monolayer on the water surface and on a substrate. The main results are as follows. (1) The formation of the H-aggregates on water, which strongly depends on the compression process, breaks C∞v symmetry, and the deposition onto a substrate gives rise to a symmetry change of the H-aggregates. (2) The average molecular tilt angles of pure and mixed hemicyanine monolayers with arachidic acid scarcely change throughout the compression process, unless the H-aggregates are formed. (3) The frequency dispersion of the dielectric constant in the monolayer should not be neglected to obtain correct susceptibility tensor elements.