bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Al(111) Crystal Orientation on Electromigration in Half-Micron Layered Al Interconnects
Authors: Shibata Hideki , Masayuki Murota Masayuki Murota , Kazuhiko Hashimoto Kazuhiko Hashimoto
Published: February 2005

A study has been done on the crystallographic effects of under-metal planes on Al(111) orientation in layered Al interconnects (Al/Ti, Al/TiN/Ti), and the dominant factor for electromigration was clarified in the region below a half-micron line width. It was found that Al(111) preferred orientation is strongly dependent on the crystal structure and process sequence of the under-metal, and universally determined by the difference between the spacing of Al(111) plane and under-metal planes. Moreover, it was found that the electromigration endurance tends to improve in proportion to the degree of Al(111) preferred orientation. Therefore, the formation of an under-metal layer with an appropriate plane whose spacing is close to that of the Al(111) plane is the most significant criterion for the realization of highly oriented Al(111) planes and hence highly reliable ULSI interconnects.
Densification of Bi1.8(Pb)0.35Sr1.9Ca2.1Cu3Ox and Texture Development through Sinter-Forging
Authors: Tampieri Anna , Masini Roberto , Dimesso Lucangelo , Malpezzi Stefano Guicciardi
Published: February 2005

A technique known as sinter-forging has been used to achieve dense Bi1.8(Pb)0.35Sr1.9Ca2.1Cu3O
x
high-T
c superconducting material with oriented grains. The relationship between the final microstructure and processing conditions was elucidated. Material density and texture increases with the hot-forging pressure and temperature. Grains are elongated with the c-axis oriented approximately parallel to the direction of applied stress. The degree of grain orientation has been quantified using X-ray diffraction and is reported in terms of Lotgering's orientation factors. A maximum orientation factor of 38% was found for processing at 830°C and 4 MPa in air. The influence of the sintering temperature and atmosphere on the electrical properties has been investigated. After processing at 810°C and 4 MPa, the sinter-forged materials exhibit superconductivity, according to resistivity measurements, with a T
c (R=0) of 104 K. The critical current density at 77 K increases with increasing bulk density.
Metallic Ag Addition Effects on Y1Ba2Cu3O7-x Superconducting Thick Films
Authors: Yamamoto Takashi , Terui Giichi , ueyama Tamotsu
Published: February 2005

Metallic Ag addition effects on Y1Ba2Cu3O7-x
(YBCO) thick film were investigated from the viewpoints of both superconducting properties and microstructure. With the addition of Ag2O (the starting material), the current density at 77 K (J
c), as well as the zero-resistivity temperature (T
c,off), was improved, resulting in J
c=1300 A/cm2 and T
c,off=93 K. The YBCO superconducting phase partly decomposed to yield Y2Ba1Cu1O5, Ba1Cu1O2 and CuO as a result of the addition of metallic Ag, which varied from Ag2O. Ba1Cu1O2, with a melting point around 900°C, promoted liquid phase sintering for YBCO. Although the YBCO superconducting phase decreased by 40 vol% as a result of these decompositions, J
c and T
c,off improved, compared with those in undoped YBCO thick film, because the YBCO was grown into a large plate and densified, and its c-direction was oriented perpendicular to the substrate.
Synthesis of Superconducting Epitaxial Films of Ba1-xKxBiO3 by Laser Ablation
Authors: Kim Hyun-Tak , Sumi Atsushi , Uwe Hiromoto , Fujita Jun-ichi , Ken-ichi Ohshima Ken-ichi Ohshima
Published: February 2005

Superconducting epitaxial films of Ba1-x
K
x
BiO3 have been synthesized by laser ablation using a stoichiometric target (x=0.4). The films were deposited at substrate temperatures of 450–550°C in argon at the pressure of 1 Torr with successive annealing at 350°C in oxygen at pressure of 1 atm. The energy density of the laser was 1.5–2.5 J/cm2 per pulse. The deposition temperature and the laser power affect the crystalline property, the superconducting property and the surface morphology. The film deposited at the substrate temperature of 510°C has the highest onset T
c of 28 K. The films oriented with respect to <100> are found to be epitaxial, using a four-circle diffractometer. Cracking in the superconducting films is not found. The film on the MgO substrate with small lattice mismatch exhibits higher zero-resistance T
c than those on the other substrates, SrTiO3 and LaSrGaO4.
A New Fabrication Process of Superconducting Nb Tunnel Junctions with Ultralow Leakage Current for X-Ray Detection
Authors: Nakagawa Hiroshi , Pepe Gianpiero , Akoh Hiroshi , Frunzio Luigi , Cristiano Roberto , Esposito Emanuela , Pagano Sergio , Peluso Giuseppe , Barone Antonio , Susumu Takada Susumu Takada
Published: February 2005

A new fabrication process is presented to make Nb/Al/AlO
x
/Nb superconducting tunnel junctions with ultralow subgap leakage current at low temperatures below 4.2 K for X-ray detection. A Nb anodization process has been adopted to make electric insulation at the periphery of an ultrathin AlO
x
tunnel barrier through use in combination with the conventional SiO self-aligned insulation process. The temperature dependence of the subgap current of the junctions fabricated by the present process is in good agreement with that predicted by the Bardeen-Cooper-Schrieffer (BCS) theory, while junctions made by the conventional process show a weak temperature dependence of the subgap current. In addition, the Vm value of the junction fabricated by the present process was found to be more than 3000 mV at 1.2 K. It has been clarified that the anodization process introduces improvements to make the subgap leakage current extremely small in the temperature range from 4.2 K down to 1.2 K.
Modulation Structures and New Type of Twin Boundary in Bi-Sr-Cu-O System Doped with Ba
Authors: Zhiqiang Mao , Li Yang , Zhen Yao , Yu Wang , Yuheng Zhang
Published: February 2005

The microstructural features of Bi2Sr2-x
Ba
x
CuO
y
(x=0, 0.2, 0.3, 0.5) compounds were characterized by means of electron diffraction (ED). In this system, a new kind of crystal defect was discovered, i.e., a 180° twin boundary between (001) and (001̄) planes. Furthermore it was also found that the positions of satellite reflection vary with the increase of Ba content x.
Ferroelectric and Antiferroelectric Properties of Solid-Solution Ceramics Ba(Ca1/3Nb2/3)O3-PbZrO3
Authors: Masaru Yokosuka Masaru Yokosuka
Published: February 2005

Studies have been conducted regarding the solid solution of the binary system Ba(Ca1/3Nb2/3)O3-PbZrO3, as part of a series of investigations on the ternary system of the transparent ferroelectric ceramics Ba(Ca1/3Nb2/3)O3-PbZrO3-PbTiO3. First, the crystal structure of the complex compound Ba(Ca1/3Nb2/3)O3 at room temperature was determined; it has a cubic disordered perovskite structure with the lattice constant a=4.185 Å. Then, for the system of xBa(Ca1/3Nb2/3)O3(1-x)PbZrO3, lattice constants, dielectric constants, electromechanical coupling factors, spontaneous polarization and thermal expansion were measured as a function of temperature for varying x (x=0-0.1). From these results, successive phase transitions from the paraelectric through the ferroelectric to the antiferroelectric phase were found. Finally, the diffuse phase transition for the composition x>0.05 was discussed.
Second-Harmonic Generation in Antiferroelectric Liquid Crystal
Authors: Fujioka Takayuki , Kajikawa Kotaro , Takezoe Hideo , Fukuda Atsuo , Kusumoto Tetsuo , Hiyama Tamejiro
Published: February 2005

We present the first observation of second-harmonic generation (SHG) in the phase-matched condition in an antiferroelectric liquid crystal (AFLC). The SH intensity profile suggests the C2 symmetry instead of the D2 symmetry expected in the ideal helicoid-unwound AFLC structure. This discrepancy is interpreted by the structural change from D2 to C2 symmetry due to a pretransitional effect of the electric-field-induced antiferroelectric-ferro-electric phase transition.
Multipage Display Using Stacked Polymer-Dispersed Liquid Crystal Films
Authors: Kato Kinya , Tanaka Keiji , Shinji Tsuru Shinji Tsuru , Shigenobu Sakai Shigenobu Sakai
Published: February 2005

This paper describes a unique multipage display, in which several images can be formed simultaneously through the pages and a desired page or pages can be displayed instantly. The multipage display consists of a stack of polymer-dispersed liquid crystal (PDLC) films. The images are formed using an electric-field-assisted thermal process, and they consist of opaque and transparent regions. Because opaque regions can be electrically switched to transparent ones without heating, the desired page(s) can be observed through the transparent pages. All the images are written through the films simultaneously using an infrared laser beam to heat selected regions all the way through the stack. The voltages applied separately to each film are controlled by the input data. Regions cooled with a field become transparent, but regions cooled without a field become opaque.
Study of Small Angle X-Ray Scattering Features of Acid- and Alkali-Treated Silk Fibre (Mulberry) Using Correlation Functions
Authors: Misra Tripurari , Panda Pramoda , Patel Tnkadhar , Dillip K. Bisoyi Dillip K. Bisoyi , Dillip K. Panda Dillip K. Panda
Published: February 2005

Silk fibres at room temperature after treatment with solutions of HCl (pH=2) and NaOH (pH=10) have been investigated using the SAXS (small angle X-ray scattering) technique. The theories developed by Vonk (1973) and Ruland (1971) for nonideal two-phase structure characterised by continuous variation of electron density at the phase boundary have been applied to calculate various macromolecular parameters such as the width of transition layer, the average periodicity transverse to the layer, the specific inner surface, the length of coherence, the transversal lengths in matter and void, the range of inhomogeneity, the volume fractions of matter and void, the volume fraction of the transition layer and the characteristic number.
X-Ray Diffraction Study on Phase Relation of BaZnGeO4
Authors: Takai Shigeomi , Hamano Akihiro , Atake Tooru , Nobuo Ishizawa Nobuo Ishizawa , Fumiyuki Marumo Fumiyuki Marumo
Published: February 2005

A single-crystal diffraction study has been carried out at 145 K, 195 K and 300 K to investigate the phase relations of BaZnGeO4. The space group of phase VI has been found to be P6122 or P6522 with the lattice parameters aVI=5.32 Å and c_VI=26.1 Å a
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Reproducibility Tests of Extended X-Ray Absorption Fine Structure for Aqua and Ammine Complexes of First Transition Metals in Solid and Aqueous Solution
Authors: Sakane Hideto , Miyanaga Takafumi , Watanabe Iwao , Matsubayashi Nobuyuki , Ikeda Shigero , Yu Yokoyama Yu Yokoyama
Published: February 2005

X-ray absorption spectra of some aqua and ammine complexes of first transition metals in solid and aqueous solution were measured and analyzed repeatedly. The parameter values of their extended X-ray absorption fine structure (EXAFS) were reproducible within about 0.01 Å in the interatomic distance and about 15% in the amplitude factor. Better reproducibilities were obtained for the samples for which the residuals of fitting calculations were small. The “error bar” was also calculated according to the method suggested at the “International Workshop on Standards and Criteria in X-Ray Absorption Spectroscopy, 1988”. It was shown that the random errors can be as small as ≤0.001 Å in distance and ≤2% in amplitude for samples with simple coordination shell structure.
Growth of GaAs Layers on Si Substrates by One-Step Low-Pressure Metal-Organic Chemical Vapor Deposition without High-Temperature Thermal Cleaning Treatment
Authors: Kiyotaka Sato Kiyotaka Sato , Kenji Togura Kenji Togura
Published: February 2005

The role of thermal cleaning treatment prior to deposition has been studied in one-step low-pressure metal-organic chemical vapor deposition (LP-MOCVD) of GaAs layers on Si(100) substrates. In the process without thermal cleaning, the surface morphologies of GaAs epilayers and the properties of Ti-GaAs Schottky junctions were affected seriously both by the exposure time of the Si substrates in air ambient and by the tilt angle of the substrates. The GaAs epilayers with mirror-like surfaces and good electrical properties were grown on the Si(100) substrates tilted 4° to the <011> direction, regardless of the high-temperature thermal cleaning process.
Electron Spin Resonance Study of Centers Formed in γ-Irradiated PbCl2 Crystals
Authors: Hirota Toyoharu , Fujita Toshiaki , Kazumata Yukio
Published: February 2005

An analisis is presented by utilizing the electron spin resonance spectra of new defects which are produced in PbCl2 single crystals irradiated at liquid nitrogen temperatures with γ-rays from a 60Co source. One of the g tensor axes of the defects corresponds to the crystallographic c-axis, and the other two make an angle of about 12° with the a- and b-axes. The components of the g-factor are g

x
=1.494±0.005, g

y
=1.322±0.005 and g

z
=1.662±0.005. The principal axes of the hyperfine coupling tensor A are collinear with neither the g tensor axes nor the crystallographic axes. The resolved hyperfine structure indicates that these defects fit a model of the paramagnetic centers consisting essentially of an electron trapped at paired lead ions, that is, the Pb2
3+ centers.
The Effects of Gaseous Helium and Nitrogen on the Thermopower Measurements: A Note of Concern for the Discrepancy of the Results Observed in High Temperature Superconductors
Authors: Panagopoulos Christos , Takeshi Fukami Takeshi Fukami , Takafumi Aomine Takafumi Aomine
Published: February 2005

We investigated the effects of gaseous helium and nitrogen on the thermopower measurements. It was observed that for a constant power supply to the heater, the temperature gradient ΔT established across the sample, lead (Pb) in our case, depended upon the thermal conductivity of the gas with which the sample vessel was filled. This affected the estimation of the thermopower S since the measured ΔT was probably a pseudo value due to the heat losses that occurred in the presence of a heat conducting gas. A qualitative model was introduced to account for the physical processes taking place during the thermopower measurements for vessels filled with heat conducting gases. The effects of gas adsorption and desorption to and from the sample respectively are also discussed.
Study on the Electrical Conduction Mechanism in Al2O3/Polyimide Langmuir-Blodgett Film Systems
Authors: Kushida Masahito , Iwamoto Mitsumasa , Hino Taro
Published: February 2005

We fabricated Al/Al2O3/polyimide Langmuir-Blodgett films (PI LB)/Al (MIM) and Al/Al2O3/PI LB/Al/Al2O3/PI LB/Al (MIMIM) junctions by means of the LB technique, and then examined the electrical transport properties of the junctions from the tan δ values of these junctions. For MIM junctions, the tunneling conduction mechanism dominated in PI LB films when the number of deposited PI LB films was less than 4. In contrast, the bulk conduction mechanism dominated when the number of deposited PI LB films was greater than 5. For MIMIM junctions, the tan δ value of the junctions was about 10% of that of MIM-external wire-MIM junctions. It was concluded that middle Al/Al2O3 layers sandwiched between top Al and base Al electrodes control the number of electrons passing through MIMIM junctions.
Reflection High Energy Electron Diffraction Observation of Dynamic Ion Beam Mixing Process in Titanium Nitride Crystal Growth
Authors: Beag Young Whoan , Min Kyung-youl , Inoue Masahiko , Kiuchi Masato , Fujii Kanenaga , Ryuichi Shimizu Ryuichi Shimizu
Published: February 2005

The initial stages of TiN crystal growth on Si substrates in the dynamic mixing method were investigated by reflection high-energy electron diffraction (RHEED) in a newly constructed ultrahigh-vacuum apparatus. The Si (001) RHEED pattern disappeared immediately after dynamic ion beam mixing started, and then was replaced by the halo pattern representing amorphous structures. The halo gradually changed to Debye-Scherrer rings representing Ti polycrystal. The results for Si (001) and (111) substrates have confirmed that the TiN crystal is controlled by the arrival ratio, Ti/N. The present RHEED pattern study has, for the first time, revealed an observable influence of the crystallography of Si substrates on TiN crystal growth.
Composition Change of Indium Oxide Film by Triethylgallium Irradiation Prepared for In Situ Selective Epitaxy Use
Authors: Ozasa Kazunari , Ye Tianchun , Aoyagi Yoshinobu
Published: February 2005

Selective epitaxy of GaAs was examined by the chemical beam epitaxy (CBE) technique on indium oxide masks. The indium oxide films were prepared in vacuum with an alternating supply of trimethylindium (TMIn) and H2O2. The irradiation of triethylgallium (TEGa) and AsH3 on the indium oxide films was performed to examine whether or not GaAs deposition takes place on the oxide films. After irradiation for 30 min above 450°C, drastic change in the chemical composition of the oxide films was observed. That is, indium atoms in the oxide films were replaced by gallium atoms. It was found that gallium atoms released on the oxide surfaces by TEGa decomposition promoted the sublimation of indium oxide through reduction. Two probable reactions are proposed for this sublimation process. The difference between indium oxide and gallium oxide in the suppression of TEGa decomposition is briefly discussed as well. The investigation shows that selective epitaxy of GaAs on the indium oxide masks can be achieved by the CBE technique using TEGa and AsH3, although the sublimation of the oxide limits the film thickness of epitaxial GaAs.
Comments on “Misorientation in GaAs on Si Grown by Migration-Enhanced Epitaxy”
Authors: Ferenc Riesz Ferenc Riesz
Published: February 2005

It is shown that the data reported by Nozawa and Horikoshi [Jpn. J. Appl. Phys. 32 (1993) 626] on the tilting of GaAs layers grown on Si by migration-enhanced epitaxy can be explained by the layer-by-layer nature of the growth process. It is also pointed out that the azimuthal angular shift of the GaAs-Si X-ray rocking curve peak position from the substrate miscut direction does not hint to the in-plane rotation of the epilayer as a whole.
In Situ Measurement of Gas-Phase Reactions in Metal-Organic Chemical Vapor Deposition of Copper Films by Fourier Transform Infrared Spectroscopy
Authors: Hanaoka Ken-ichi , Ohnishi Hiroshi , Kunihide Tachibana Kunihide Tachibana
Published: February 2005

In situ Fourier transform infrared (FT-IR) measurement has been performed in a metal-organic chemical vapor deposition (MOCVD) technique using a source material which is solid at room temperature. First, methods to introduce purge gas into a CVD reactor to prevent raw materials and thermally decomposed products from depositing onto the KBr windows were examined. We were able to separate spectra of gaseous pure source materials and those of species adhered on the KBr windows under the optimum flow rate of purge gas. Then, in situ IR spectra of Cu(DPM)2 were measured in detail in the CVD reactor. The results of measured spectra showed that no change of the chelate carbonyl region occurred, and that two new peaks appeared, of which intensities increased with the increase of the substrate temperature. The dependence corresponded well to the change of the atomic composition in the films deposited on SiO2.
Dynamic Mechanical Behaviour of Thin Metal-Layer Coated Polyethylene Terephthalate Films under Torsional Oscillation
Authors: Isuke Ouchi Isuke Ouchi , Takashi Tanaka Takashi Tanaka
Published: February 2005

Co-Cr or Ni thin layers were deposited on both sides of a polyethylene terephthalate (PET) film by sputtering. Complex rigidity moduli of these films were measured by a torsional oscillation method under a load of 6.8×105 Pa between room temperature and 200°C. The real and imaginary parts of the complex moduli of the coated films were explainable, qualitatively, in terms of those of the base film and thin metal layers using a simple composite model. The loss moduli of Co-Cr layers were small, as previously shown by a nonresonant, forced stretching oscillation method, while those of Ni were definitely greater in the temperature range above 130°C. Cracks occurred in Ni above 165°C and in Co-Cr at higher than 180°C under the minimal load mentioned above.
Reduction Mechanism for Spherical and Chromatic Aberration Coefficients of Magnetic Lens and Retarding Electric Fields
Authors: Mamoru Nakasuji Mamoru Nakasuji , Hiroyasu Shimizu Hiroyasu Shimizu
Published: February 2005

Aberrations generated by the magnetic lens, the aperture lens and the retarding field lens are calculated separately using the electron beam trajectories. Most of the chromatic aberrations for the magnetic lens and retarding electric field system are generated by the magnetic lens. The chromatic aberration coefficient for the system is reduced by the factor (landing beam energy/initial beam energy), because the beam is not yet retarded in the magnetic lens. The spherical aberration coefficient is reduced because the beam semiangle is increased by the retarding field lens. The aperture lens generates negative-sign aberration and reduced the total aberration for the system; however, its absolute value is the smallest among those generated by the other two lenses.
Effect of Adsorbed Matter on Intense Pulsed Ion Beam Generation
Authors: Hashimoto Yoshiyuki , Mitsuyasu Yatsuzuka Mitsuyasu Yatsuzuka , Sadao Nobuhara Sadao Nobuhara
Published: February 2005

Generation of intense pulsed ion beams with high purity has
been studied experimentally. Impurity ions in the ion beams were
found to be caused by adsorbed matter on the anode and residual gas
molecules in the diode chamber. The first few shots without
breaking vacuum in the diode chamber were found to be effective to
remove the adsorbed matter on the anode, and lead to higher purity
of the ion beams. No effect on the ion beam current was observed
upon changing the residual gas pressure in the range from 10-2
to 10-3 Pa or upon leaving the anode in atmosphere for
∼10 h. Residual gas molecules in the diode chamber had little
effect on the purity of the ion beams. After the first 5 shots, the
current of the ion beams was found to be 3.0 kA. The most dominant
species in the ion beams was F2+.
Investigation of Reoxidation and Phosphorus Behavior in HF-Treated Heavily Doped Silicon Surfaces
Authors: Kamiura Yoshitomo , Mizokawa Yusuke , Iida Makio , Isobe Yoshihiko , Kawamoto Kazunori
Published: February 2005

The thermally stimulated desorption (TSD) from aqueous HF-treated heavily phosphorus-doped Si(100) and polycrystalline Si surfaces was studied by Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS) and mass spectroscopy. Desorption analyses indicated that reoxidation takes place slightly, to the same extent in the doped Si(100) and polycrystalline Si surfaces owing to hydrogen desorption. Moreover, a large quantity of phosphorus segregates to the top few layers in the desorption process of the oxides. It was clarified that the HF-treated polycrystalline silicon surface is terminated by hydrogen and resists oxidation similarly to a single-crystal one.
Anisotropic Ridge Growth by Step-Flow-Mode Metalorganic Chemical Vapor Deposition Using Diethylgalliumchloride
Authors: Ko-ichi Yamaguchi Ko-ichi Yamaguchi , Kotaro Okamoto Kotaro Okamoto
Published: February 2005

In selective metalorganic chemical vapor deposition, ridge growth of GaAs was investigated with respect to step-flow-mode growth using diethylgalliumchloride. Although the flat surface of selective epilayers was easy to obtain due to the reevaporation-enhancement effect, anisotropic ridged layers were also observed. The growth form of the ridged layers depended upon crystal orientation of striped mask patterns, off-angle of vicinal (100) substrates and step-flow velocity. Step-flow velocity in the [011] direction was 1.6 times higher than that in the [01?1] direction; as a result, long ridged layers were formed along the [011] direction.
Film Property Control of Hydrogenated Amorphous Silicon Germanium for Solar Cells
Authors: Terakawa Akira , Shima Masaki , Sayama Katsunobu , Tarui Hisaki , Tsuda Shinya , Hidenori Nishiwaki Hidenori Nishiwaki , Shoichi Nakano Shoichi Nakano
Published: February 2005

The optoelectric properties of a-SiGe:H alloys, deposited by the plasma chemical vapor deposition (plasma-CVD) method, were investigated with precise measurement of their germanium content (C
Ge) and hydrogen content (C
H). This investigation revealed that the optical gap of a-SiGe:H alloys can be approximated by a linear function of C
H and C
Ge and various combinations of C
H and C
Ge resulted in identical optical gaps. For each optical gap, the optimum composition for the lowest defect density was derived by comparison with the subgap absorptions measured by the constant photocurrent method (CPM). Based on these, the highest conversion efficiency of 3.7% under red light illumination (>650 nm) for a 1 cm2 a-SiGe single-junction solar cell was achieved.
Lattice-Mismatched InGaAs Double Heterojunction Bipolar Transistors Grown on GaAs Substrates
Authors: Jr. Hiroshi Ito
Published: February 2005

We propose lattice-mismatched InGaAs double heterojunction bipolar transistors (HBTs) fabricated on a GaAs substrate as a new structure for simultaneously reducing power dissipation and improving the electron transport properties. Increasing the In composition in the base and collector layers is effective for reducing the turn-on voltage but causes an increase in the generation current in the collector depletion region and a softening of the breakdown characteristics in the base-collector junction. By optimizing the layer structure for HBTs, the current gain reaches 20 with a base doping of 1?1019/cm3 in spite of the existence of a relatively high dislocation density. The turn-on voltage for an In0.3Ga0.7As base layer at a collector current density of 103 A/cm2 is approximately 0.9 V. The InGaAs HBT can be used also as a phototransistor covering the 1.2-1.5 ?m wavelength region.
The Behavior of Bilateral Latch-Up Triggering in VLSI Electro Static Discharge Damage Protection Circuits
Authors: Huang Heng-Sheng , Chang Chun-Yen , Hsu Chen-Chung , Chen Kun-Luh , Lin Jyh-Kuang
Published: February 2005

A new latch-up phenomenon that shows symmetrical diac I-V characteristics has been discovered recently. Electrical measurements show that a diac parasitic semiconductor-controlled-rectifier (SCR) device can exist between two adjacent electro static discharge damage (ESD) protection circuits or output buffers. The SCR consists of two parasitic P-N-P-N paths and can easily induce a localized SCR latch-up between two adjacent input or output terminals. This is not similar to traditional latch-up that creates a parasitic P-N-P-N path between power supply and ground pins, but is a new bilateral latch-up path between two adjacent input and output pins. A new latch-up failure mode due to this diac structure, which creates a bilateral path during temperature humidity bias (THB) testing, is discussed. Some suggestions regarding the improvement of this diac latch-up degradation are proposed. Advanced analyses and modeling are also presented in this paper. The modified diac latch-up lumped element model successfully explains this phenomenon.
Mechanical Effects of Hafnium and Boron Addition to Aluminum Alloy Films for Submicrometer LSI Interconnects
Authors: Onoda Hiroshi , Takahashi Eishi , Kawai Yasuaki , Madokoro Shoji , Fukuyo Hideaki , Sawada Susumu
Published: February 2005

This is the first report on the mechanical properties of hafnium- and boron-added Al-Si-Cu alloy film for LSI interconnects. Two to three hundred ppm of hafnium and boron addition into Al-Si-Cu alloy film does not influence the Al alloy properties for metal lines as LSI interconnects, such as its low resistivity, low ohmic contact resistance with Si, and fine-line patterning feasibility. The mechanical properties of the Al alloy film, however, change greatly. Vertical hillock and lateral hillock formation is considerably suppressed during heat treatments used in LSI fabrication processes. Stress-induced void formation is also reduced during aging test at 125?C. These effects due to hafnium and boron addition are considered to be an impurity precipitation effect ihat was confirmed by X-ray diffraction analysis and electron probe microanalysis.
Hydrostatic Pressure Effects on Superconductive Phase Transitions in Y1-xCaxBa2Cu3O7-? and Y(Ba1-yLay)2Cu3O7-?
Authors: Tomoyuki Hikita Tomoyuki Hikita , Masayuki Ogasawara Masayuki Ogasawara
Published: February 2005

Pressure effects on the superconductive transitions of cation replaced YBa2Cu3O7-?: Y1-x
Ca
x
Ba2Cu3O7-? (0?x?0.2) and Y(Ba1-y
La
y
)2Cu3O7-? (0?y?0.15) were investigated. The electric resistivity was measured up to 2 GPa as a function of temperature. The dT
c/dp decreases with increasing y for Y(Ba1-y
La
y
)2Cu3O7-?, giving 1.0 K/GPa for YBa2Cu3O7-? and 2.9 K/GPa for Y(Ba0.85La0.15)2Cu3O7-?. For La replacement, the oxygen content was almost unchanged. Therefore, the replacement of Y by La led to electron doping. The pressure derivative of T
c indicates that the pressure induces hole doping whose effect is increased with the increase of La contant. Contrary to our expectation, Y1-x
Ca
x
Ba2Cu3O7-? was not hole-doped but electron-doped because of the increase in the oxygen deficiency with Ca content. However the dT
c/dp is almost independent of x.
Effects of Pulling Direction on Directional Growth of YBa2Cu3O7-x Superconductors
Authors: No Kwangsoo , Shin Woosuck , Bae Sungjoon , Cho Changhyun , Kim Guneik Jang
Published: February 2005

The effects of the pulling direction (upward and downward) on the microstructure and the superconducting properties of the textured bulk YBa2Cu3O
x
high-temperature superconductor samples fabricated using extrusion and directional growth of the superconductor grains reacted from Y2BaCuO5, BaCuO2 and CuO powder mixtures were studied. Compared to the pulled-down sample, the pulled-up sample showed relatively dense and well-textured microstructure, high critical temperature and high critical current density.
Design of Waveguide Grating Based on Simulated Annealing and Narrow-Band Modulation
Authors: Wu Jie , Takashi Kondo Takashi Kondo , Ryoichi Ito Ryoichi Ito
Published: February 2005

A new method for designing optical waveguide grating structures by an optimization technique is proposed based on the concept of narrow-band modulation. A grating profile is considered as a high-frequency periodic grating modulated by a slowly varying binary function. To make the optimization algorithm as robust as possible, a digital vector is introduced to describe the binary function, and simulated annealing is employed to perform the optimization. Several examples of grating design are given. They show that the method offers a great freedom with the least human intervention, for designing a variety of reflection characteristics that are significantly different from those of conventional grating structures.
Continuous Wavelength Tuning of Inter-Valence-Band Laser Oscillation in p-Type Germanium Over Range of 80-120 ?m
Authors: Komiyama Susumu , Hiroshi Morita Hiroshi Morita , Iwao Hosako Iwao Hosako
Published: February 2005

Wavelength tuning of inter-valence-band (IVB) laser oscillation in p-Ge is successfully carried out by incorporating a mechanically variable lamellar grating into the laser resonator. A wide tuning range (80-120 ?m), comparable to the whole spectral domain of IVB oscillation (shorter-wavelength domain), is achieved with fixed electric and magnetic fields at liquid helium temperatures. The best spectral purity of the oscillation lines reaches the limit of instrumental resolution (???0.5 ?m).
Laser Scanning Mode Interference Contrast Microscope and Its Application to Step Height Measurement
Authors: Ooki Hiroshi , Arimoto Rieko , Shionoya Takashi , Matsuura Keiji , Iwasaki Jun
Published: February 2005

The image contrast of the laser scanning mode interference contrast (LASMIC) microscope is descrihed. Some experimental results show the high performance of the LASMIC microscope in visualizing small phase changes on the surface of the sample. Furthermore, as a new application of the LASMIC microscope, quantitative measurement of step heights using LASMIC signals is proposed. The principle of this measurement is described theoretically and its effectiveness is verified experimentally.
Collimation of Two-Dimensional Ballistic Electrons Using Equivalent Snell's Law
Authors: Noguchi Mitsuhiro , Hideki Sakakibara Hideki Sakakibara , Toshiaki Ikoma Toshiaki Ikoma
Published: February 2005

We proposed and successfully demonstrated a method to collimate electron waves propagating in a two-dimensional (2D) electron waveguide, using equivalent Snell's law for equilibrium electrons. The angular distribution of ballistic electrons emitted into a 2D electron gas formed at a high-quality AlGaAs/GaAs heterointerface was measured under a magnetic field, and an electron collimation effect was experimentally confirmed. The electron collimation can be controlled by changing the voltage applied to a collimation gate which is placed in front of the electron injector. This technique can be applied to a double-quantum-well electron-wave switch for improving the switching ratio.
Heterostructures of Pb(ZrxTi1-x)O3 and YBa2Cu3O7-? on MgO Substrate Prepared by Pulsed Laser Ablation
Authors: Wu Nai Juan , Ignatiev Alex , Mesarwi Abdul-Wahab , Lin He , Shih Kan Xie
Published: February 2005

Ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films were integrated to high-T
c superconducting YBa2Cu3O7-? (YBCO) films in PZT/YBCO/MgO(100) and YBCO/PZT/MgO(100) stacking structures by the pulsed laser ablation technique. The YBCO films in both structures were superconducting and c-axis oriented. The PZT films in both structures were of the perovskite structure having the (100) orientation. The detailed profile of PZT/YBCO interface was determined for the ferroelectric constituents. The ferroelectric properties of the PZT films were characterized in the temperature range of 40 K to 300 K. The remanent polarization was above 15 ?C/cm2 and the coercive field was 46 kV/cm at room temperature. The cycling fatigue and the loss tangent were improved at low temperature.
Dielectric Properties and Ferroelectric Domain of BaTiO3 Powders
Authors: Hsing-I Hsiang Hsing-I Hsiang , Fu-Su Yen Fu-Su Yen
Published: February 2005

A systematic study of the particle size dependence of the ferroelectric domain, internal stress and dielectric constant (K) of BaTiO3 powders was performed using scanning electron microscopy, X-ray diffractometer and differential scanning calorimetry. The dielectric constant of BaTiO3 powder was lower than that of the BaTiO3 sintered body. Low values of the dielectric constant were observed for BaTiO3 powder, which was ascribed to low domain density and constrained forces existing in the particles. As the particles became smaller due to the decrease in the constrained force powders of lower domain density are formed.
EL2 Out-Diffusion in Thermally Annealed Liquid-Encapsulated Czochralski GaAs
Authors: Ogata Junzo , Iwai Akiyoshi , Shigefusa Chichibu Shigefusa Chichibu , Satoru Matsumoto Satoru Matsumoto
Published: February 2005

The annealing behavior of the native defect EL2 in GaAs grown by the liquid-encapsulated Czochralski (LEC) method has been investigated by means of deep-level transient spectroscopy (DLTS). After annealing in vacuum, the EL2 out-diffusion profiles were strongly dependent on the annealing temperature and time. Applying the three-step model for EL2 out-diffusion, the activation energy of the diffusion for an arsenic vacancy (V
As) was estimated to be about 3-4 eV.
Diamond Synthesis by Microwave-Plasma Chemical Vapor Deposition Using CH3Cl and CH2Cl2 as Carbon Source
Authors: Takayuki Nagano Takayuki Nagano , Noriyoshi Shibata Noriyoshi Shibata
Published: February 2005

Polycrystalline diamond films have been synthesized from gas mixture systems of CH2Cl2-H2 and CH3Cl-H2 by the microwave-plasma chemical vapor deposition (CVD) technique. The gas reaction speed was promoted by using CH3Cl and CH2Cl2, although the deposition rate decreased, due probably to surface etching by the chlorine in the case of high-concentration CH2Cl2. A broad band centered at about 1500 cm-1 in the Raman spectra decreased considerably in the films compared with those synthesized from the CH4-H2 gas mixture. Very little residual chlorine was detected in the deposited films. The use of chlorine-permuted methane as a carbon source was found to be advantageous for high-purity diamond deposition at low temperature and high concentration.
Interaction of Hydrogenated Silicon Nitride Films with Indium Tin Oxide
Authors: Kimura Etsuko , Kawachi Genshiro , Konishi Nobutake , Matsukawa Yuka , Sasano Akira
Published: February 2005

The whitening mechanism of hydrogenated silicon nitride (SiN
x
:H) film deposited on indium tin oxide (ITO) film was investigated by means of optical emission spectroscopy (OES), scanning electron microscopy (SEM) and X-ray photoelectron spectrosscopy (XPS) analysis. The degree of whitening of the SiN
x
:H film on ITO depends on the deposition conditions of SiN
x
:H, i.e., the SiH4 flow rate and the substrate temperature. Reactive species such as SiH
n
, decomposed from SiH4 gas, preferentially caused the reduction of ITO. This was followed by formation of In metal and a Si-rich porous layer containing SiO2. An abnormal growth of SiN
x
:H films caused by these successive reactions led to the whitening.
X-Ray Photoelectron Spectroscopy of Fluorocarbon Films Deposited by RF Sputtering
Authors: Yoshinori Yamada Yoshinori Yamada , Toshiji Kurobe Toshiji Kurobe
Published: February 2005

Fluorocarbon films are deposited by rf sputtering of poly(tetrafluoroethylene) targets under conditions of various power and pressure levels in pure argon in order to examine the effect of discharge conditions on the deposition rate and molecular structure of the deposited films. The molecular structures of the films are investigated by means of X-ray photoelectron spectroscopy. The films deposited under conditions favoring high deposition rate, such as higher power at a constant pressure or lower pressure at a constant power, contain higher concentrations of cross-links. Heating the deposited films results in an increase in the component of the C1s spectrum assigned to the cross-linked structure.
Electron Cyclotron Resonance Discharge of Gas Sublimated from Decaborane by CO2 Laser Irradiation
Authors: Ito Yoshifumi , Terasawa Takeshi , Naoki Kanazawa Naoki Kanazawa , Masahiro Nishikawa Masahiro Nishikawa
Published: February 2005

Stable plasmas are produced by electron cyclotron resonance (ECR) discharge of gas sublimated from decaborane in the solid state by CO2 laser irradiation. Spectroscopic measurements of resonance line emissions reveal that the density of the sublimation gas is proportional to the square root of the input power of the CO2 laser. Emissions from boron atoms are due to dissociative excitation of the gas, and those from the ions are due to excitation after dissociative ionization. The electron temperature and the density of helium plasmas are about 6 eV and (0.5–3.0) ×10^11 c
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Dynamic Characteristics of Bimorph with Conducting Polymer Gel
Authors: Shakuda Shuzo , Morita Shigenori , Tsuyoshi Kawai Tsuyoshi Kawai , Katsumi Yoshino Katsumi Yoshino
Published: February 2005

A bimorph consisting of poly(3-alkylthiophene) gel film and polypyrrole film has been prepared for the first time and demonstrated to be driven by electrochemical doping. The bend of the bimorph can be controlled by the doping potential, that is, by the dopant concentration. The response time can also be controlled by the doping potential and electrolyte concentration. Anomalous responses have been observed for excess doping levels. The origin of this unique behavior of the bimorph was discussed by taking the role of the dopant in the gel film into consideration.
Construction of Sample Holder for X-ray Diffraction Experiments on Supercritical Fluids
Authors: Keiko Nishikawa Keiko Nishikawa , Masakazu Takematsu Masakazu Takematsu
Published: February 2005

A sample holder for X-ray diffraction experiments on supercritical fluids has been constructed. The holder with Be windows of 2 mm thickness has endured the inner sample pressure of up to 10 MPa, and the temperature of the sample has been changed in the range of 0-60?C. Preliminary diffraction experiments for a supercritical CO2 fluid and a high-pressured CO2 liquid near the critical point have been carried out using the sample holder and a detector with an imaging plate. The total accumulation time was about 1 h. Use of the present equipment enables X-ray diffraction experiments on supercritical fluids to be carried out very easily.
New Method for Studying Surface and Interface Structures Using Kossel Lines
Authors: Toshio Takahashi Toshio Takahashi , Masamitu Takahasi Masamitu Takahasi
Published: February 2005

The angular dependence of Kossel lines from Ge single crystals excited by monochromatized synchrotron radiation was measured precisely in the double-crystal arrangement where the first crystal acts as a sample and the second as an analyzer. The Kossel line profiles showed surface sensitivifies when the excitation beam was incident on the crystal surface at a small angle or when its wavelength was slightly shorter than the absorption edge of Ge. The profiles were compared with the calculations based on the dynamical theory using the reciprocity theorem. The relationship with the X-ray standing wave method was clarified.
Ultrafine Particle Beam Deposition I. Sampling and Transportation Methods for Ultrafine Particles
Authors: Kizaki Yoshimi , Osada Hiroshi , Hiroshi Aoki Hiroshi Aoki , Satoshi Yamazaki Satoshi Yamazaki
Published: February 2005

A new approach using a system in vacuo with a dynamic gas flow named “ultrafine particles beam deposition,” was proposed as a technique for handling ultrafine particles. To create a gas beam flow, three types of sampling and transportation methods for ultrafine particles were tested. In these sampling and transportation methods, the sampling method using a skimmer and differential pumping gave the best results since it enables sampling of hot ultrafine particles soon after they are produced and carries them without collision in a directional gas flow. A narrow size distribution for ultrafine particles ranging from 3 nm to 13 nm could be obtained in the case of ultrafine Fe particles. As a result, the deposited film obtained using such small ultrafine particles showed a metallic luster as grown and characteristics such as specific electric resistance, coercive force and crystalline property similar to those of bulk Fe metal.
Modeling Thermal Diffusion of Scanned and Focused Laser Power on Direct Overwrite Magneto-Optical Disk
Authors: Saito Jun , Morita Kazuhisa , Kurita Shinichi , Doi Masaaki , Aoki Yoshikazu , Hideki Akasaka Hideki Akasaka
Published: February 2005

A simple analytical model with three fitting parameters could simulate the thermal diffusion of scanned and focused laser power on a direct overwrite (DOW) magneto-optical (MO) disk. Three different experiments on the disk give the three fitting parameter values. The thin film structure of the DOW-MO disk has no aluminum layer which current MO disks have, so that the total thermal diffusivity of DOW-MO disks is less than that of the current MO disk. However, the thermal response functions of DOW-MO disks and the current MO disk are not greatly different. Accordingly, as well as the current MO disk, the DOW-MO disk is suitable for high data density recording using the technique of thermal interference uniforming (TIU) to make uniform mark edge shifts. Without TIU, the shifts of edges would depend on the pattern of recorded data.
Diffraction Pattern from Magnetooptical Edges
Authors: Yamamoto Masakuni , Hoshi Hiroaki , Yamaguchi Eiji , Susumu Matsumura Susumu Matsumura
Published: February 2005

We describe an optical edge-detection system that can detect magnetooptical (MO) edges giving the phase shift 0 or π radians to the Kerr component light in the MO data storage. The interference between the diffraction wavefront from the MO edge within a diffraction limited spot and the reference wavefront gives appropriate intensity distribution for the optical edge detection. We calculated the diffraction patterns from the MO edge using the boundary-element method and observed them experimentally using the Twyman-Green interferometer. The two sets of results are in good agreement.
Optimized Disk Structure and Ge-Tb-Sb Composition for Overwritable Phase Change Compact Disk
Authors: Terada Masato , Furuya Kazuyuki , Okamura Tatsuya , Isao Morimoto Isao Morimoto , Masafumi Nakao Masafumi Nakao
Published: February 2005

We have investigated a disk structure and recording film composition suitable for the overwritable phase change compact disk. A high performance has been achieved at low linear velocity using the rapid cooling structure and the recording film composition of Ge25Te48Sb27.
Improvement in Jitter Characteristics in Mark Edge Recording for Phase Change Media
Authors: Ohkubo Shuichi , Okada Mitsuya , Murahata Michio , Tatsunori Ide Tatsunori Ide , Toshiaki Iwanaga Toshiaki Iwanaga
Published: February 2005

This paper describes improvement in jitter characteristics in mark edge recording (MER) for phase change media at a high linear velocity. Jitter of the mark edge position, usually caused by thermal and/or intersymbol interference, can also increase due to overwrite when MER is used with phase change media. We have found that the main cause of jitter increase due to overwrite is the difference in absorptivity between the amorphous and the crystalline states. We were able to reduce jitter significantly by controlling absorptivity through the use of a Si reflective layer. It was also confirmed that this improvement in jitter characteristics can achieve high recording density of 0.59 µm/bit.
Magnetooptic Head Using Substrate-Mode Grating Pairs for Polarization and Leaky Beam Splitting
Authors: Yang-Tung Huang Yang-Tung Huang , Yeong-Her Chen Yeong-Her Chen
Published: February 2005

A novel substrate-mode grating pair structure for polarization and leaky beam splitting is presented for application to magnetooptic heads. These light weight and compact elements provide better flexibility and easier alignment for system applications. Optimum designs for these two types of beam splitters and theoretical evaluation of the system performance are discussed in detail. Preliminary experimental results are also given to demonstrate the feasibility of application of these substrate-mode grating pairs in a magnetooptic head.