bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of Layer Thickness and Composition Variations of AlxGa1-xAs Crystals for Diffusion-and Electromigration-Limited Growth
Authors: Kato Kiyoko , Hiroshi Okuda Hiroshi Okuda , Kazuo Nakajima Kazuo Nakajima
Published: February 2005

We propose a model for calculating variations in growth rate and composition of III-V ternary crystals whose growth is limited by diffusion and electromigration. The model simultaneously satisfies both conservation of mass and phase equilibrium. In the calculation for Al
x
Ga1-x
As crystals, we found that solute transport in the solution is related to parameters such as the diffusion coefficients of solute elements in the solution, the mobility of migrating solute elements, and the electric field in the solution. These parameters play an important role in the growth of ternary compound semiconductors.
Preparation of MgO Thin Films by RF Magnetron Sputtering
Authors: Kaneko Yasuhisa , Mikoshiba Nobuo , Tsutomu Yamashita Tsutomu Yamashita
Published: February 2005

MgO thin films were prepared on Si(100) substrates by RF magnetron sputtering using a Mg, or MgO target. The preferred orientation of MgO thin films using a Mg target was transformed from a (200) plane to a (111) plane as a function of substrate temperature. The preferred orientation of MgO thin films using a MgO target was observed only in the (200) plane.
Preparation of Superconducting Bi-Pb-Sr-Ca-Cu-O Compounds by Oxalate Coprecipitation
Authors: Chen Dian-Hau , Shei Cheng-Yie , Shyang-Roeng Sheen Shyang-Roeng Sheen , Chau-Ting Chang Chau-Ting Chang
Published: February 2005

Bi1.6Pb0.4Sr2Ca2Cu3O
y
has been prepared from an ethylene glycol medium that contains starting metal nitrates via homogeneous coprecipitation using triethylammoniumoxalate and oxalic acid. The theoretical estimate on the conditions of oxalate coprecipitation and preliminary characterization of the properties of the Bi1.6Pb0.4Sr2Ca2Cu3O
y
obtained after the high-temperature treatment are reported. The preparation of this five-component system of Bi, Pb, Sr, Ca and Cu using triethylammoniumoxalate and oxalic acid has worked successfully in a large-quantity preparation of up to 200 g per batch.
Adhesion between Photoresist and Inorganic Substrate
Authors: Kawai Akira , Nagata Hitoshi , Takata Haruhiko Abe
Published: February 2005

Adhesion strength of a photoresist during pattern development decreases as penetration of an alkaline aqueous solution into the photoresist film increases. The penetration is accelerated by increasing the quantity of residual solvent in the photoresist film. Resistance measurements confirmed the penetration. The tensile stress of photoresist films increases as the penetration increases. The creation of inner stress also causes adhesion failure during HF etching. These phenomena cannot be explained by a balance model of surface energy. Therefore, we conclude that the increase in tensile stress causes adhesion loss during both pattern development and HF etching.
Preparation of YBa2Cu3Oy Superconducting Thin Films by Radio-Frequency Plasma Flash Evaporation
Authors: Fukagawa Wataru , Komori Kazunori , Fukutomi Masao , Tanaka Yoshiaki , Asano Toshihisa , Hosokawa Hiroshi Maeda
Published: February 2005

An attempt has been made to deposit superconducting thin films using low-pressure plasma flash evaporation. The rf plasmas used were sustained at 20-30 Torr by the 13.56 MHz rf generator operated at 10 kW. A dense and lustrous film was obtained at the deposition rate of about 10 Å/s. The best film on (100)MgO showed a sharp resistive transition with T
c (ρ=0) as high as 91 K and the J
c of 1.3×104 A/cm2 at 77 K and zero field.
Profiling of Double-Crystal X-Ray Diffraction of InGaAs Epilayers Grown on GaAs
Authors: Okamoto Kotaro , Hajime Tosaka Hajime Tosaka , Ko-ichi Yamaguchi Ko-ichi Yamaguchi
Published: February 2005

In0.12Ga0.88As epilayers were grown by a direct growth (DG) process and a two step growth (TG) process and analyzed by measuring the profile of the diffraction angle and full width at half maximum (FWHM) of double-crystal X-ray diffraction (DXRD). In the case of the DG process, rectangular-shaped grains are surrounded by highly dislocated boundaries, which are observed as crosshatches. Profiles of DXRD indicate that both epilayer and substrate of as-grown samples contain a strain. In the case of TG process, both the region growing coherently and the region containing a high density of defects appear along the heterointerface and the latter acts as an absorber of misfitstrain. As a result, the epilayer is almost free from strain.
Two-Dimensional Measurement of Electrical Surface Charge Distribution on Insulating Material by Electrooptic Pockels Effect
Authors: Kawasaki Toshiyuki , Yujin Arai Yujin Arai , Tatsuo Takada Tatsuo Takada
Published: February 2005

The image produced by a surface electrical discharge and the amount of charge were studied by the Pockels effect of a BSO single-crystal cell. The cell has only one transparent metal plate electrode which is located at the rear surface of the cell and is grounded. Electrical surface charges are placed on the other surface by a high-voltage discharge between the rear plate electrode and a point electrode. The applied impulse voltage on a 1.0-mm-thick cell had a peak of approximately 6 kV. An 8-mm-diameter discharge figure was obtained using a charge-coupled device (CCD) camera which was placed behind the rear electrode. The maximum charge density on the cell calculated from image processing was 70 nC/cm2. Using circular polarized incident light, the polarity of the surface charge was determined. These results are closely related to the charge densities obtained by other methods.
Population Inversion in Mixing Hydrogen Gas with a High Temperature Plasma
Authors: Furukane Utaro , Sato Kuninori , Takiyama Ken , Oda Toshiatsu
Published: February 2005

Inverted population distributions in the hydrogen atom which appear in the contact phenomenon of hydrogen gas with high-temperature helium plasma are analyzed by a collisional-radiative model associated with energy balance equations. By including the ion temperature effect in the energy balance equations, the collisional-radiative model indicates an inverted population of the hydrogen in the same-order range as the experimentally observed ones. The possibility of lasing at the 656 nm line of hydrogen is discussed in connection with initial conditions of helium plasma and injected hydrogen gas.
The Electrochemical Behavior of Anodically Electrodeposited Iridium Oxide Films and the Reliability of Transmittance Variable Cells
Authors: Kazusuke Yamanaka Kazusuke Yamanaka
Published: February 2005

The electrochemical properties of anodically electrodeposited iridium oxide films are investigated for application to transmittance variable cells. The reactivity of electrochromic reaction of the film increases with the increase in water content in LiClO4 propylene carbonate electrolyte, and decreases with increasing temperature of the heat treatment after electrodeposition. The coloration potential E of the film depends on the proton activity in the electrolyte, and increases linearly with the hydrogen electrode potential E' of the electrolyte at a slope of 1.0. This means that the coloration is caused by the release of H+ from the film or by the injection of OH- into the film. The reliability of transmittance variable cells made with the films is tested.
Development of ac Calorimetric Method for Thermal Diffusivity Measurement IV: Films with Low Thermal Diffusivity and Very Thin Films
Authors: Yuqin Gu Yuqin Gu , Ichiro Hatta Ichiro Hatta
Published: February 2005

In the ac calorimetric thermal diffusivity measurement of a thin film with low thermal diffusivity and a very thin film, it happens that the atmosphere surrounding the films significantly affects thermal diffusivity measured when the contribution of propagation of ac temperature waves in the atmosphere is not neglected. In fact, the measurement in a polymer film or in a very thin film should be carried out under vacuum, in which ac temperature waves no longer propagate. The experimental tests were made for polypropylene films and a borosilicate glass plate. The measurement under vacuum is not always required for every kind of film. The condition which is required for the measurement in the air is discussed. In addition, various problems which occur in the measurement of thin films with low thermal diffusivity and very thin films are considered.
Accuracy of Intensity Measurement by Use of an Area Detector with a Photostimulable Phosphor Screen, as Confirmed by Measuring Scattering Intensity from a Liquid
Authors: Nishikawa Keiko , Yasuhiro Sakamoto Yasuhiro Sakamoto , Takao Iijima Takao Iijima
Published: February 2005

An area detector using a photostimulable phosphor screen, namely an imaging plate (IP), has been applied to the intensity measurement of X-ray scattering from liquid CCl4. The scattering intensity in the present experiment has been compared with that determined by means of an energy-dispersive method. The two intensities have agreed well with each other. It has been proved that the use of the IP detector makes it possible to measure the scattering intensities of halo patterns precisely with much shorter accumulating time with a simple procedure of analysis and that there is no effect of the oblique incidence of scattering X-rays to the IP at high scattering angles.
The Effect of Condenser Tilt on Optical Projection Lithography
Authors: Terasawa Tsuneo , Hama Katsunobu , Tawa Tsutomu , Souichi Katagiri Souichi Katagiri
Published: February 2005

A basic study on the imaging characteristics of wafer steppers influenced by a condenser tilt is presented. The effects of condenser tilt are explored by displacing the source images formed on the entrance pupil plane of a projection lens. The intensity distribution of the wafer surfaces influenced by this condenser tilt is obtained by the two-dimensional aerial intensity simulation method based on Fourier optics. Periodic line pattern images are shown to shift due to the condenser tilt when the image plane is out of focus. It is also suggested that the degree of these image shifts increases as the focal error increases and the pattern feature sizes increases, and these image shifts for large feature sizes are approximated by geometrical shifts.
Deformation of Vesicles under the Influence of Strong Electric Fields II
Authors: Hyuga Hiroyuki , Jr. Kazuhiko Kinosita, , Nobuyoshi Wakabayashi Nobuyoshi Wakabayashi
Published: February 2005

Dynamics of vesicle deformation in a pulsed electric field has been studied in the framework of perturbation theory. The membrane is assumed to be initially insulating and to become a conductor after a cerain period of time, t
p, by electroporation. The dynamical behavior was found to be influenced not only by t
p but also by the ratio of the conductivity inside the vesicle and that outside.
Liquid Phase Epitaxy Growth and Properties of GaInAsSb/AlGaAsSb/GaSb Heterostructures
Authors: Xiuying Gong , Bauhua Yang , Yindi Ma , Fensheng Gao , Ying Yu , Wenjian Han , Xuefeng Lui , Jinying Xi , Zuanguo Wang , Lanying Lin
Published: February 2005

The GaInAsSb/AlGaAsSb/GaSb heterostructures were grown by the liquid phase epitaxy (LPE) technique. The materials were characterized by means of optical microscopy, electroprobe microanalysis (EPMA), double-crystal X-ray diffraction, capacitance-voltage (C-V) and Van der Pauw measurements, infrared absorption spectra, photoluminescence and laser Raman scattering. The results show that the materials have fine surface morphology, low lattice mismatch and good homogeneity. Room-temperature light-emitting diodes with an emission wavelength of 2.2 µm were obtained by using the GaInAsSb/AlGaAsSb DH structures.
Preparation and Properties of Si Microcrystals Embedded in SiO2 Glass Films
Authors: Yamamoto Masaki , Hayashi Ryo , Tsunetomo Keiji , Kohno Kenji , Yukio Osaka Yukio Osaka
Published: February 2005

Si microcrystals were successfully doped into SiO2 glass films by the rf magnetron sputtering technique. The dependence of the average size of Si microcrystals on substrate temperature was discussed with reference to transmission electron microscopy observations. The optical absorption spectra of Si microcrystals clearly exhibited the blue shift compared with a bulk Si crystal, which seems to be due to a quantum size effect.
Resonant Raman Scattering in ZnS
Authors: Kanie Hisashi , Nagano Masahiro , Masaharu Aoki Masaharu Aoki
Published: February 2005

Three Raman lines were observed in addition to excitonic emission lines in cubic ZnS using a He-Cd laser 325 nm line. The lines were assigned to the Raman lines of the laser line scattered by one or two phonons. The energies of the LO phonon and the TO phonon were estimated to be 44 meV and 35 meV from the energy of the Raman lines. These values agreed well with those measured by right-angle Raman scattering with an Ar laser 514.5 nm line. With the rise in temperature from 4.2 K, the intensity of the Raman lines declined until 80 K and was then enhanced to about 130 K. The temperatures where the intensity was enhanced corresponded to those where the energy of the free exciton level approached the energies of the Raman lines. The temperature dependence of the Raman intensity was interpreted in terms of resonance between the incident or scattered light with the temperature-dependent free exciton level.
Complex Susceptibility of YBa2(Cu1-xCox)3Oy
Authors: Mazaki Hiromasa , Katsuyama Shigeru , Kosuge Hiroshi Yasuoka
Published: February 2005

The superconducting transition of YBa2(Cu1-x
Co
x
)3O
y
compounds was measured in terms of complex susceptibility, χ=χ′-iχ′′. Samples were prepared in two different ways in the range of 0≤x≤1/3. Group I was fabricated by the ordinary oxidization treatment (slow cooling from 850°C in flowing O2 gas). Group II was prepared by heating in flowing N2 gas at 800°C for 20 h, followed by slow cooling to room temperature in the same atmosphere and then by annealing in flowing O2 gas below 400°C for more than 20 h. The transition curves observed for the samples of the two different groups seem to be essentially the same, except the transition temperature. However, careful examinations of the profiles of χ have revealed that the substituted Co atoms in group II cluster to some degree in the Cul-O planes, although the degree of clustering is not distinctive as in the Fe-doped samples.
Fourier-Mellin Transform and the Invariant Image Moments
Authors: Yajun Li Yajun Li
Published: February 2005

Relationship between the algebraic invariants and the Fourier-Mellin transform of an image irradiance distribution function is revealed. Method is developed for deriving the image moment functions that are invariant with respect to image translation (shift), rotation and size changes without the aid of the theory of algebraic invariants.
Field-Induced Strain of Chemically Prepared Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics
Authors: Ando Toshinori , Ryuji Suyama Ryuji Suyama , Kei Tanemoto Kei Tanemoto
Published: February 2005

Field-induced strain and dielectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics, which are prepared via a wet-chemical process, are studied. The compositions containing 6∼8 mol% PbTiO3 give a relatively large strain of 0.51∼0.68×10-3 with small hysteresis at room temperature.
Effects of Heavy Doping of MgO on Characteristics of LiNbO3
Authors: Hu Long-Jang , Chang Yen-Hwei , Lin I-Nan , Tu Shuenn-Lih , Yang Sheng-Jenn
Published: February 2005

Heavily doped LiNbO3 single crystals were successfully grown using the Czochralski technique. The MgO solubility was, as determined from transmittance and X-ray diffraction data, less than 30 mol% in this crystal. The site-occupancy refinement study reveals that all of the Mg2+ ions incorporated into LiNbO3 will occupy A-site lattices. They first expel the Nb5+ ions which reside in this site and then create vacancies at the same site. The Curie temperature thereafter increases firstly with the MgO content and decreases again when the concentration of MgO goes beyond a certain limit. The C-constant of the Gallagher model, T
c=K-C·C
v, is estimated to be C
b=3333.3 for lightly doped materials and C
a=300.0 for heavily doped materials. The former is due to the decrease in B-site vacancies, while the latter is ascribed to the increase in A-site vacancies.
Thermally Stimulated Exoelectron Emission from BaTiO3 Ceramics
Authors: Watanabe Yoshihisa , Igarashi Yoshikazu Nakamura
Published: February 2005

Glow curves and energy spectra of thermally stimulated exoelectrons are reported for several BaTiO3 ceramics, including pure ceramics, which have a negative temperature coefficient (NTC) of resistivity, and positive temperature coefficient (PTC) ceramics. The surface potentials of these materials are measured at temperatures up to 250°C in air. Glow peaks are not easily observed in pure BaTiO3 ceramics excited by X-rays. However, several glow peaks are readily detected between 40°C and 250°C in PTC ceramics, with especially strong emissions occurring in the semiconductor region below 100°C. Distinct glow peaks are not observed in the same temperature region in the NTC ceramics. These results could be related to the facts that the surface of the PTC ceramics was charged positively and that the potential increased with increasing temperatures.
Surface Segregations during Epitaxial Growth of Fe/Au Multilayers on GaAs(001)
Authors: Ken-ichi Sano Ken-ichi Sano , Tsugio Miyagawa Tsugio Miyagawa
Published: February 2005

The epitaxial growth process of Fe/Au multilayers on GaAs(001) substrates at temperatures of between 300 and 573 K has been studied using reflection high-energy electron diffraction and Auger electron spectroscopy. The growth mode is identified as the layer-by-layer type. Surface segregations of As, Ga, Fe or Au atoms that constitute substrates and underlayers were observed during the growth processes of these multilayers, depending on the deposition condition. These surface segregations can be removed by sputter etching for a short period, and resegregation is not observed afterwards. Differences in the mechanisms of these and conventional surface segregations are discussed.
Study of Blackening Effects of Indium-Tin Oxide by Depositing Sputtered Ta2O5
Authors: Yoshiki Chubachi Yoshiki Chubachi , Kazushi Aoyama Kazushi Aoyama
Published: February 2005

When Ta2O5 dielectric film was deposited on an indium-tin-oxide (ITO)-coated glass substrate by rf reactive sputtering, the blackening of ITO was observed. It was confirmed that the residual gas during sputtering is related to the blackening of ITO. The presputtering in argon-oxygen mixture gas and the following evacuation to basal pressure (less than 1×10-6 Torr) yield Ta2O5 films without ITO blackening.
Formation of Current Leakage Paths at the Interface between Dielectrics in Intense Electric Fields in a Gas Discharge Display Device
Authors: Mikoshiba Shigeo , Kitagawa Shinichi Shinada
Published: February 2005

Electrically conducting paths were formed at the interface between a soda-lime glass substrate and a lead-glass overglaze in a gas discharge display panel under an electric field of 7 kV/cm. This resulted in the panel malfunctioning after 4000-h operation. The current leakage paths consisted of Pb atoms, produced by the reduction of PbO by Na ions. The rate of path formation was strongly sensitive to the electric field, substrate temperature, and also to the presence of ionized gases in the vicinity of the interface. Methods of avoiding insulation failure include using a Pb-free dielectric overglaze, sandwiching the electrodes between lead glasses, and reducing the intensity of the electric field.
Annealing Effect on Mechanical Stress in Reactive Ion-Beam Sputter-Deposited Silicon Nitride Films
Authors: Fourrier Alain , Bosseboeuf Alain , Daniel Bouchier Daniel Bouchier , Guy Gautherin Guy Gautherin
Published: February 2005

Optical properties and mechanical stress of silicon nitride films deposited at room temperature by ion-beam sputtering are studied for various compositions in the range of N/Si=0.6 to N/Si=1.4. The refractive index and mechanical stress are investigated before and after annealing by ellipsometry and the Newton ring method. The silicon-rich film extinction coefficient and stress value decrease after annealing. These property variations are explained by a high structural disorder in films deposited at room temperature which is lowered during annealing. The study of a layer deposited at high temperature (600°C) enables us to check the thermal stress effect in the film. A stress evaluation in the film and at the Si3N4-Si interface shows that sputter-deposited silicon nitride is suitable for the local oxidation of silicon.
The Effective Ionization Coefficient in SF6/Xe-Mixtures
Authors: Hilmert Hartmut , Schmidt Werner F. , Sakai Yosuke , Sawada Sadao
Published: February 2005

The effective ionization coefficient, {α}/p was measured for mixtures of sulphur hexafluoride and xenon over a wide range of compositions. A charge collection method was employed the basic features of which are discussed. The data were analyzed by numerical solution of the Boltzmann-Equation with proper cross sections.
Impurity Content Characterization of Brazilian Quartz Lascas
Authors: Iwasaki Hideo , Iwasaki Fumiko , Oliveira Virginia A. R. , Hummel Daniele C. A. , Pasquali Maria A. , Guzzo Pedro L. , Noêmia Watanabe Noêmia Watanabe , Carlos K. Suzuki Carlos K. Suzuki
Published: February 2005

Lattice impurities (Al, Li, Fe) free from the influence of cations in inclusion liquid were evaluated by atomic absorption spectrophotometry (AAS) in quartz lascas taken from 10 deposits with known localities in three states, Minas Gerais, Tocantins and Bahia. Levels of Al content and associated Li content depend on the localities of deposits. Quartz deposit regions with high Al content are composed of granite, gneiss, and pegmatite as surrounding rocks. It was concluded that the charge compensation for Al-Si substitution in quartz lascas was realized substantially by the formation of Al-Li and Al-OH centers which were confirmed from the linear relation of Al-Li plots by AAS data and IR spectra due to Al-OH center. The variety in Al-Li and Al-OH correlations was attributed to the fluctuation of growing conditions of quartz in nature.
Effect of Ferrite Magnetic Wedge on Capacitor Motor Characteristics in Triac Control
Authors: Kaga Akio , Yoshihisa Anazawa Yoshihisa Anazawa , Katsubumi Tajima Katsubumi Tajima
Published: February 2005

Split-phase capacitor motors are commonly used to drive household electric appliances. The motor has some slots and teeth to embed electric conductors or coils. The presence of the slots and teeth induces the variation of magnetic reluctance through the magnetic circuit to introduce heavy pulsation of the air gap flux. Thus, the voltage, current and torque of the motor become oscillative to increase the electric power loss and finally to reduce the motor efficiency. First, the authors discuss the characteristics of a 3-phase cage-type induction motor in which the ferrite magnetic wedges have been installed into the stator slot openings of the motor to smooth the air gap flux pulsation and to decrease the electric power loss, resulting in improved motor efficiency. If the motor is driven by the voltage source in accordance with the loading condition, more economical operation will be achieved. In this study, a nonsinusoidal voltage controlled by the switching element of a triac has been applied to a capacitor motor with wedges of ferrite magnetic materials. This paper reports on the interesting results obtained.
Determination of Pole Distribution for Thin Film on a Thick Substrate by X-Ray Diffraction
Authors: Takashi Ishiguro Takashi Ishiguro
Published: February 2005

In the case of thin films grown on such a thick substrate that the X-rays cannot pass through, the available methods for measurement of X-rays to determine the pole distribution in the film are the reflection methods, although they have unobservable angle zones in common. In order to cover such a blind zone and to get a particular pole distribution in the film over the entire angle range, different pole distributions are obtained and are united into one normalized pole distribution by making reference to the pole distribution in an ideal sample with random orientation of crystallites. The simple combination method proposed here is applied to the determination of the normalized (00·2) pole distribution in sputtered hexagonal Co thin films.
Characteristics of Hot Electron Ring in a Simple Magnetic Mirror Field
Authors: Minoru Hosokawa Minoru Hosokawa , Hideo Ikegami Hideo Ikegami
Published: February 2005

Characteristics of a hot electron ring are studied in a simple magnetic mirror machine. Hot electron rings (n≈1010 cm-3, T≈100 keV) are most effectively generated under two conditions, when the magnetic field on the axis of the midplane is set near the fundamental, or the second harmonic electron cyclotron resonance to the applied microwave frequency (6.4 GHz). The density profile of the hot electrons is observed to take a so-called ring shape. The radial-cut view of the ring, however, indicates an M-shape density profile, and the density of hot electrons on the axis at the center and is about one-half of the peak ring density encircling the axis. The hot electron ring is susceptible to a few instabilities which can be artificially triggered. With the instability generated, the hot electron ring is observed to transform into a filled cylinder in a few microseconds and then disappears.
A Method to Protect CR-39 Track Detector from Sunlight
Authors: Ahmad N. , Mirza Nasir M. , Sikander M. Mirza Sikander M. Mirza , M. Tufail M. Tufail
Published: February 2005

It has been shown that the track revealing properties of CR-39 track detectors are affected if the irradiated detectors get sunlight exposure. These properties can be preserved if the detectors are wrapped in black carbon paper.
Radical- and Ion-Induced Reactions on Plasma-Deposited Silicon Surfaces
Authors: Miyazaki Seiichi , Kiriki Yoshihiro , Yushi Inoue Yushi Inoue , Masataka Hirose Masataka Hirose
Published: February 2005

A neutral or partially ionized hydrogen or deuterium beam was irradiated onto a silicon thin film produced by silane radical beam condensation on a cooled substrate to study the interaction of silane plasma with a solid surface. The volatile chemical species created by the beam-induced surface reactions have been evaluated by mass spectrometry. It is shown that partially ionized deuterium beam irradiation induces the evolution of HD and partially deuterated silanes from the surface and results in the incorporation of deuterium atoms in the silicon surface layer to form SiHD bonds. The accelerated hydrogen ion beam irradiation produces Si2H6 molecules on the surface in addition to SiH4 and H2 surface products. A chemically inert argon ion beam with energies higher than the plasma potential causes physical sputtering and the desorption of H2, SiH4 and Si2H6.
Control of Reaction Mechanism of Photochemical Vapor Deposition of Aluminum Film by Timing of Source Introduction
Authors: Sahara Kouji , Hideki Ouchi Hideki Ouchi , Mitsugu Hanabusa Mitsugu Hanabusa
Published: February 2005

In photochemical vapor deposition of aluminum film using dimethyaluminum hydride (DMAH) under illumination of a deuterium lamp, a photolytic reaction became dominant when silicon wafer was exposed to DMAH at room temperature prior to substrate heating to 230°C for deposition, while only a pyrolytic reaction took place when DMAH was introduced after the substrate was heated to 230°C. A scanning tunneling microscope study showed formation of Al islands in high density with the DMAH exposure, while well-isolated islands were revealed without the initial exposure. Activation sites created by chemisorption may be responsible for the observed effects.
Low-Temperature Etching for Deep-Submicron Trilayer Resist
Authors: Kure Tokuo , Kawakami Hiroshi , Enami Shinichi Tachi
Published: February 2005

The effects of Cl2 addition to O2 plasma used for deep-submicron trilayer resist etching are investigated. The bottom-layer organic resist is etched using a low-temperature microwave plasma etcher. With O2+Cl2 etching gas, highly anisotropic etching is achieved at higher temperatures than with pure O2. Cl2 concentrations above 25% reduce resist selectivity relative to the SOG intermediate layer. Vertical 0.1-µm-wide resist patterns are achieved with O2+25% Cl2 at -60°C. Broadened resist patterns with tapered side walls are produced at lower temperatures and at higher Cl2 concentrations; this is thought to be caused by chlorine passivation and polymer deposition on the side walls.
The Variation of InxGa1-xSb Solid Compositions with the Vapor Phase Mole Fractions at Different Growth Pressures in Metal Organic Chemical Vapor Deposition
Authors: Su Yan Kuin , Fuh Shyang Juang Fuh Shyang Juang , Tien Shou Wu Tien Shou Wu
Published: February 2005

InxGa1-xSb epitaxial layers have been grown on (100) GaSb substrates at 600°C under different growth pressures of 100 and 170 Torr. From both analyses of X-ray diffraction and photoluminescence (PL), the variation of indium solid composition (x
s) with vapor phase composition (x
v) for both 100 and 170 Torr growths were studied. The distribution coefficient (the ratio x
s to x
v) is found to be smaller than unity. The result is similar to but slightly higher than those reported by Bougnot et al. The In solid compositions grown at 170 Torr were found to be higher than those grown at 100 Torr. The energy gaps of In
x
Ga1-x
Sb epilayers were deduced from photoluminescent peaks (10 K). The relationship between energy gap (10 K) and indium solid composition for different growth pressures of 100 and 170 Torr was studied and compared with the numerical results reported by Auvergne et al. The photoluminescence peak intensity was found to decrease quickly with increasing lattice mismatch between In
x
Ga1-x
Sb epilayers and GaSb substrates.
Floating Potential in Negative-Ion-Containing Plasma
Authors: Haruo Shindo Haruo Shindo , Yasuhiro Horiike Yasuhiro Horiike
Published: February 2005

For a feasibility study of low-energy etching at low pressures, the floating potential in negative-ion-containing plasma was theoretically investigated. The sheath equations into which the effect of the negative ion was incorporated was numerically solved. The results showed that the floating potential with respect to the plasma potential decreased in its absolute value with an increase in the negative ion concentration, and thus it is suggested that low-energy etching would be possible even in low-pressure plasma. A particular emphasis was given on the floating potential showing an abrupt decrease at a certain value of the negative ion concentration with relatively low negative ion temperature, and this was applicable to the digital etching technique.
A Laser Welding and Scribing (LWS) Method for a High-Yield Integrated-Type a-Si Solar Cell
Authors: Kishi Yasuo , Murata Kenji , Inoue Hiroshi , Kiyama Seiichi , Ohnishi Michitoshi , Shoichi Nakano Shoichi Nakano , Yukinori Kuwano Yukinori Kuwano
Published: February 2005

A new fabrication method for integrated-type amorphous-silicon (a-Si) solar cell submodules, called the laser welding and scribing (LWS) method, was investigated. The conditions for laser scribing and laser welding were calculated from a three-dimensional thermal analysis of a multilayer structure. Calculated results were confirmed by experiment, and the optimum laser power density range for scribing was found to be much wider than that for conventional laser patterning methods. Subsequent connection of adjacent cells in a series by laser welding was also easily performed. This fabrication method has led to a total area conversion efficiency of 10.3% for a 100 cm2 integrated-type a-Si solar cell.
High-Efficiency Delta-Doped Amorphous Silicon Solar Cells Prepared by Photochemical Vapor Deposition
Authors: Higuchi Katsuhiko , Tabuchi Katsuya , Lim Koeng Su , Makoto Konagai Makoto Konagai , Kiyoshi Takahashi Kiyoshi Takahashi
Published: February 2005

Amorphous Si solar cells with delta-doped (δ-doped) p-layers were prepared by a multichamber photochemical vapor deposition (photo-CVD) system. By optimizing the structure of the δ-doped p-layer, a conversion efficiency of 12.3% (AM1) was obtained for small-area solar cells with a δ-doped p-layer using B2H6 as a dopant source. The δ-doped p-layers deposited with trimethylboron (TMB) and triethylboron (TEB) as new boron sources were characterized. It was found that the boron layers obtained with TMB by photo-CVD contain a large amount of carbon atoms which degrade the solar cell performance. Carbon contamination was suppressed both by the plasma CVD method with a gas mixture of TMB, H2 and He and by the photo-CVD method with TEB.
Reduction of Gap State Density in a-SiGe:H Alloys
Authors: Watanabe Takeshi , Tsuzuku Susumu , Matsubara Sunao , Muramatsu Shin-ichi , Shimada Toshikazu
Published: February 2005

The reduction of the gap states in a-SiGe:H alloys down to the level in a-Si:H was realized by the low-pressure microwave plasma chemical vapour deposition (CVD) which utilizes hydrogen plasma stream. It was found that the densities of defect states and tail states in the alloy vary with the flow rate of hydrogen introduced into the deposition chamber, and a-SiGe:H alloy with low defect density was attained with an optimized flow rate of hydrogen when the flow rate of source gas (SiH4 and GeH4) was reduced. The Urbach energy also decreased when the flow rate of hydrogen was optimized, and a-SiGe:H alloy with an Urbach energy of 48 meV was obtained. It was also found that the photoconductive property of a-SiGe:H alloys is not sensitive to the density of gap states.
A New Type of Amorphous Silicon Solar Cell with High Thermal Stability
Authors: Teruhisa Kanbara Teruhisa Kanbara , Shigeo Kondo Shigeo Kondo
Published: February 2005

A new type of solar cell has been developed with hydrogenated amorphous silicon (a-Si:H). The cell structure is glass/ITO/(P-a-Si:H)/(I-a-Si:H)/(SiO
x
-complexes)/(Al+O-complexes). In comparison with a conventional PIN-type a-Si solar cell glass/ITO/(P-a-Si:H)/(I-a-Si:H)/(N-a-Si:H)/Al, the new-type cell gives much higher stability against thermal degradation which is caused by internal diffusion of Si and Al at the interface of the back-side electrode on the solar cell. The conversion efficiency of the conventional cell decreased from 6% to less than 1%, but the new-type cell maintained the same efficiency of 5.2% (AM1, 100 mW/cm2) after the storage at 120°C for 20 days. The new-type cell has the open circuit voltage V
oc=0.86 (V), short-circuit current J
sc=12 mA/cm2, and fill factor ff.=0.50, yielding conversion efficiency of η=5.2% under AM1.0 of 100 mW/cm2, and V
oc=0.62 (V), J
sc=18 µA/cm2, ff.=0.73 under a white fluorescent lamp of 200 lx. These photovoltaic parameters are almost the same as those of conventional PIN-type a-Si solar cells. In this paper, fabrication and photovoltaic performance of the thermal stability of the new-type cell are discussed in comparison with conventional solar cells.
High-Gain Collector-Top Ge/GaAs Heterojunction Bipolar Transistors with a Base Layer Fabricated by Suppressing Ga Atom Diffusion at Ge/GaAs Heterojunctions
Authors: Kawanaka Masafumi , Tohru Kimura Tohru Kimura , Jun'ichi Sone Jun'ichi Sone
Published: February 2005

Collector-top Ge/GaAs heterojunction bipolar transistors (HBTs), consisting of an n-type GaAs emitter, a p-type Ge base, and an n-type Ge collector, are fabricated successfully. These exhibit a current gain of 430, the largest among reported collector-top HBTs. Ga atom diffusion into the Ge base layer from the surface of the GaAs emitter layer is suppressed using a two-step Ge growth process, wherein a thin Ge film is grown on GaAs at lower growth temperature prior to normal Ge growth at 500°C. For HBTs with low-temperature-grown (LTG) Ge films of 150 Å thickness, the current gain increases monotonically from 45 to 430 with decreasing LTG film growth temperature from 500°C to 150°C. Insertion of an LTG Ge film lowers the total amount of Ga atoms diffused from the Ge/GaAs heterointerface by one order of magnitude, and reduces both the base width and the doping density of the base layer, resulting in an increase in current gain.
In-situ Calibration for Electric Field Measurements in Glow-Discharge Plasmas by Laser-Induced Fluorescence Using the Optogalvanic Technique
Authors: Yamagata Yukihiko , Kawano Yasuhiko , Muraoka Katsunori , Maeda Mitsuo , Akazaki Masanori
Published: February 2005

We proposed and performed an in-situ calibration of electric field determination in glow-discharge plasmas based on the Stark effect, to relate ratios of laser-induced fluorescence (LIF) intensities (forbidden/allowed) with electric fields E, where accurate E values were measured by the laser optogalvanic (LOG) method. The results were compared with Bell Lab Group static calibration, and yielded 30% lower E value at a given fluorescence intensity. It is discussed, by the aid of solutions of rate equations for the LIF processes, that the present calibration is more accurate at higher electric field (E>100 V/mm) than that obtained by extrapolation of Bell Lab Group results at lower field (E<94.3 V/mm). Also, in the course of this comparison, the value of electric dipole moment for BCl was estimated to be µ=0.93±0.02 Debye.
Photoluminescence Line at 2.29 eV in CuGaS2 Crystal
Authors: Sho Shirakata Sho Shirakata , Shigehiro Isomura Shigehiro Isomura
Published: February 2005

A series of photoluminescence (PL) lines has been observed at 4.2 K in CuGaS2 single crystals grown by an iodine-transport method. They consist of a sharp sero-phonon line at 2.294 eV and phonon replicas. This PL series is discussed in connection with the phonon-assisted transitions observed for the zero-phonon lines at 2.397 and 2.404 eV.
Discharge Plasma and Sheath as a Stochastic Process –What the | f |-α Power Spectral Law Implies–
Authors: Noboru Tanizuka Noboru Tanizuka
Published: February 2005

Noise signals detected with a Langmuir probe from a DC magnetron plasma device are discussed. Noise spectra were characterized by the | f |-α power law with α being the constant stochastic index. α ranged between 2.5 and 5.5 in the frequency range of 0.1<f<2 MHz and was formulated by α≈log
e 16I
d
0.6 with I
d being the discharge current in milliampere. The noise spectra are discussed by the autocorrelation function which reveals a memory included in the signals. It is stressed that noise is related to the formation of a sheath (boundary layer) across which charged particles are transported. It is analogized to cell membrane noise and cosmic noise.
Refractive Index Ellipsoids of a Polyformal Magneto-Optical Memory Disk Substrate
Authors: Shigematsu Kazuyoshi , Shirouzu Shigenori , Sakamoto Shuji , Togawa Sohshi , Mikiya Hayashi Mikiya Hayashi , Takashi Nakagawa Takashi Nakagawa
Published: February 2005

In order to decrease the refractive index anisotropy of constructive units (RIAC), the substitutions of carbonate groups by formal groups were performed. The relationships between chemical structures and RIAC, stress-optical coefficients in glassy state (C
g) and molecular motions in polyformals were investigated, and some low-RIAC polyformals were obtained. The anisotropy of refractive index ellipsoids in a magneto-optical memory disk substrate made by one of these low-C
r polyformals decreased to 1/6 those of a bisphenol-A-polycarbonate disk substrate.
The Effects of Valence States of Manganese on Electrical Properties of ZnO Varistors
Authors: Chen Ying-Chung , Shen Chi-Yen , Chen Hone-Zern , Wu Yin-Fang Wei
Published: February 2005

The electrical characteristics of ZnO varistors with various valence states of manganese were studied. The composition containing low valence state of manganese exhibits low donor concentration, trap density and barrier height. The compositions with lower trap density have the characteristics of higher nonlinear coefficient, higher voltage ratio and lower leakage current. The electrical properties were improved by increasing the sintering temperature and time. It is also found that the depression angle decreases as a function of the increasing sintering time and temperature. The relaxation time for τ3 decreases with increasing sintering time. It indicates an enhancement in the degree of uniformity in trapping conductance and the trap emission/capture rate when sintering time increases. The dependence of the depression angle and relaxation time on the composition have been also presented. On the other hand, the dependence between the electrical properties and wetting behavior of intergranular phase is investigated.
A Hysteresis Model for Antiferroelectric SmCA
* Phases
Authors: Masahiro Nakagawa Masahiro Nakagawa
Published: February 2005

In this paper, we shall present a simple irreversible rotation model with a couple of polarization vectors to account for the hysteretic phenomena in SmCA
* phases. From a numerical calculation, a double hysteresis curve was found in antiferroelectric SmCA
* phase, whereas a single curve was found in the ferroelectric SmC* phase. Remarkably it is found that there exists a direct ferroelectric-ferroelectric transition under a sinusoidal electric field with a sufficiently large amplitude and high frequency in qualitative agreement with experimental findings.
An Improved Preparation Method of Ultrafine Particles by Gas Evaporation with Arc Plasma Sputtering
Authors: Hiroo Oya Hiroo Oya
Published: February 2005

A preparation method of metallic ultrafine particles by means of arc plasma sputtering was improved so as to be applicable to various materials including semiconductor materials. A higher production rate of ultrafine particles was achieved, for example, 380 mg/min, 420 mg/min and 230 mg/min for iron, silver and silicon, respectively.
Use of Glass Beads Filter in Scanning Fabry-Perot Interferometry
Authors: Dodo Taro , Sugawa Masao , Fumiaki Hashimoto Fumiaki Hashimoto , Nobuyuki Matsuki Nobuyuki Matsuki
Published: February 2005

In FIR spectrometry, an interference low-pass filter is used to cut the harmonics of a Fabry-Perot interferometer (FPI). The interference low-pass filter has sharp cutoff characteristics, but has leakage at higher harmonics of the cuton frequency. The appropriate sized glass bead filter can suppress this leakage. The combined use of an interference filter and a glass bead filter gives good performance in FIR spectrometry.
Subgrain Structure and Dislocation Density of Annealed MCT
Authors: Nöllmann Ida , Alicia B. Trigubo Alicia B. Trigubo , Noemi E. Walsöe de Reca Noemi E. Walsöe de Reca
Published: February 2005

X-ray topography (reflexion Lang method) was employed to observe the subgrain structure of MCT (Hg1-x
Cd
x
Te with x=0.2) after annealings under different conditions. Dislocation density (δ) was evaluated in chemically etched MCT specimens both by optical and electron scanning microscopies.
Ingots were grown by the Bridgman method. Cutting, polishing and etching conditions of MCT wafers are specified. Dislocation density of wafers of ingots I (annealed 10 days at 610°C) was δ≃108 cm-2 while that of ingots II (annealed 30 days at 650°C) was of δ≃106 cm-2.
Micrographic and X-ray topography observations revealed results in agreement as regards to the mean area values of sub-grain substructure as well as to the misorientation angles between neighbouring subgrains.
Reduction of Interface Defect Density by Hydrogen Dilution in a-Si:H/ZnS Multilayer Films
Authors: Morimoto Akiharu , Yutaka Nishio Yutaka Nishio , Tatsuo Shimizu Tatsuo Shimizu
Published: February 2005

a-Si:H/ZnS multilayer films were prepared by glow discharge decomposition of a silane gas and a diethylsulfur-diethylzinc gas mixture, and the effect of hydrogen dilution in the preparation was investigated. It was revealed, through ESR and electrical measurements, that the hydrogen dilution of the silane gas down to 3% during deposition suppresses the formation of interface defects, resulting in the enhancement of both the photoconductivity and the photoluminescence. However, it was also revealed through IR measurements that a-Si:H and ZnS tend to result in an alloying around the interface.
Asymmetrical Emission Profiles from Low-Frequency Discharges in SF6 and in N2 Gases in a Planar Diode with a Si-Wafer
Authors: Suganomata Shinji , Ishikawa Itsuo , Junichi Tanaka Junichi Tanaka , Hideo Ozaki Hideo Ozaki
Published: February 2005

Asymmetrical emission profiles were observed on such spectral lines as F I 703.7 and S II 545.4 nm from SF6 discharge, and N2 337.1 and N2
+ 391.4 nm from N2 discharge. The intensity ratio of N2
+ 391.4 to N2 337.1 clearly shows that the observed asymmetries originate from the asymmetrical field distribution induced by an electrically floating Si-wafer mounted on one of the two plane electrodes.
Hybrid Films Formed from Hexamethyldisiloxane and SiO by Plasma Process
Authors: Kashiwagi Kunihiro , Yoshida Yasuhiko , Yoichi Murayama Yoichi Murayama
Published: February 2005

Hexamethyldisiloxane (HMDSO) based films containing silicon monoxide (SiO) were obtained by a plasma process. The HMDSO hybrid films were prepared on the substrates by evaporating SiO during HMDSO plasma polymerization in rf discharge. SiO was evaporated by heating in rf plasma consisting of HMDSO and oxygen at a pressure of the order of 10-4 Torr. The structures of the HMDSO hybrid films thus obtained were analyzed by fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra. The structures of the HMDSO hybrid films containing SiO were also analyzed by FTIR. The ratio of Si/C in the hybrid films formed under the HMDSO monomer gas pressure at 7×10-4 Torr were found to be about 1.5 by XPS spectra. The HMDSO hybrid films were found to be pinhole free, and exhibited the characteristics of electrical insulators.
Calcium Stearate Thin Films Evaporated onto NaCl
Authors: Okuyama Katsuro , Kazuhiro Tada Kazuhiro Tada , Shigetoshi Ohshima Shigetoshi Ohshima
Published: February 2005

Crystallographic orientation of calcium stearate thin films evaporated onto cleaved NaCl was investigated as a function of substrate temperature and deposition rate. At substrate temperatures below ∼50°C, needlelike crystallites of calcium stearate were grown epitaxially with their c axis parallel to the <110> directions of the NaCl substrate (two-directional lateral orientation). At substrate temperatures above ∼70°C, the c axis of the deposited films was normal to the substrate and the [110] calcium stearate was parallel to the <110> NaCl (normal orientation). One-directional lateral growth, i.e., the c axis of the crystallites is pointing in only one direction, was observed in a relatively large area of the film, most frequently at substrate temperatures between 55 and 65°C.
Plasma-Enhanced Chemical Vapor Deposition of Copper
Authors: Nobuyoshi Awaya Nobuyoshi Awaya , Yoshinobu Arita Yoshinobu Arita
Published: February 2005

Plasma enhanced copper chemical vapor deposition (CVD) using acetyl-acetonato copper as a source compound is investigated for VLSI metallization. Results show that electrical resistivity and film morphology are greatly dependent on substrate temperature, and that plasma enhancement results in smooth copper film formation. Hydrogen is essential for reducing oxygen and carbon incorporation of copper film. A smooth surface film of low electrical resistivity (1.8 µΩcm) is obtained by plasma-enhanced CVD with hydrogen carrier gas at the substrate temperatures between 200°C and 280°C. Investigation of the step coverage of the film results in the coverage of the trench being superior to that of the sputtering method.