bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of the Deterioration of Luminescence Efficiency of P-53 Phosphor Due to Electron Bombardment
Authors: Ohno Katsutoshi , Abe Tomohiko , Kusunoki Tsuneo
Published: February 2005

In order to withstand high excitation power density for the long operational lifetime required, preparation processes have been improved to reduce the deterioration of the luminescence efficiency of P-53 phosphors due to electron bombardment. The effects of several factors on the luminescence efficiency and the resistivity to high electron bombardment were evaluated. P-53 phosphors should be single-phase cubic YAG and have good surface crystallinity. In order to compensate for the change in charge by Ba2+(flux) taken up inside the phosphor particles, addition of tetravalent metal compounds to the starting materials was performed and the addition of SiO2 was found to be effective. As a result, the deterioration of brightness due to electron bombardment could be reduced by about 70%, while high luminescence efficiency was maintained.
Preparation and Characterization of Superconducting Y–Ba–Cu–O Films by the MOCVD Technique
Authors: Ohnishi Hiroshi , Kusakabe Yoshihiko , Kobayashi Minoru , Hoshinouchi Susumu , Harima Hiroshi , Tachibana Kunihide
Published: February 2005

Superconducting Y–Ba–Cu–O thin films were obtained by the MOCVD technique on MgO(100) substrates at 715°C without postannealing. β-diketonate chelates were used as source metal organic complexes. This paper describes the film characterizations of electrical resistivity, composition, surface morphology and microstructure. Superconducting films were composed of a dense matrix and dispersed particles. The Y–Ba–Cu composition of the matrix was close to the 1:2:3 superconducting phase, while the particles were mainly composed of CuO. The highest zero-resistant temperature obtained in this experiment was 85 K. The film was highly oriented with the c-axis normal to the substrate. The lattice constant of the film was 11.68 Å.
AC Conductivity of Amorphous Fe2O3–Bi3O3 Oxide Glasses
Authors: Chaudhuri B. K. , Som K. K. , Ghosh A.
Published: February 2005

The frequency-dependent ac conductivity of an iron-bismuth semiconducting ferrite glass in the frequency range of 102–105 Hz and in the temperature range of 77 to 450 K is reported. The experimental data have been analysed with reference to various theoretical models based on the quantum mechanical tunneling through the barrier and the classical hopping over the barrier. The analysis shows that the correlated barrier hopping (CBH) model is the most appropriate one for the present semiconducting glasses. This model predicts quantitatively the temperature dependences of both the ac conductivity and its frequency exponent. However, the other existing theoretical models, such as quantum mechanical tunneling (QMT) and the overlapping large polaron tunneling (OLPT) model, are not consistent with the experimental data.
Fermi Level Effect on Compositional Disordering of AlAs/GaAs Superlattice
Authors: Ogawa Kazuhisa , Kawabe Mitsuo
Published: February 2005

The Fermi level effect on impurity-induced compositional disordering of the AlAs/GaAs superlattice has been investigated by studying the disordering at the surface. It is shown that the Si-induced disordering is suppressed at the surface and the thickness of the suppressed layer depends on the Si concentration; that is, the superlattice with the larger Si concentration has the thinner suppressed layer. These results indicate that the surface suppression effect originates from the surface depletion layer where the Fermi level is pinned near the midgap, and that the intermixing is explained by the Fermi level effect.
Determination of Charge and Level Shift of Manganese in Some Manganese Chemicals and Ores by X-Ray Emission Spectroscopy
Authors: Acharya B. S. , Pradhan Rajeev
Published: February 2005

X-ray emission spectra usually give a direct picture of the occupied states above Fermi level and the K emission band reflects the distribution of electrons of p-symmetry in the outer levels. The `3d' transition metal compounds exhibit a wide variety of properties due to their valence band consisting of s, p and d like states. These `d' states are strongly localised and influence the properties of the compounds through s-d, p-d hybridization. In the present investigation, the level shift of the 2p3/2 states of Mn in MnO2, MnPO4, MnSO4, KMnO4, δ-MnO2, Mn-Nodule and BCS-Mn-Ore has been determined. Besides, the spectrum of Mn has been resolved into several bands like A, B, F, G and X following the Gaussian peak assumption. It has been found that the binding energies of all chemicals and ores except KMnO4 show higher value compared to pure Mn 2p3/2 state and quadrupole transitions have negligible effect on the X-ray transitions.
The 1/f2 Noise Spectrum Derived from Electromigration–Induced Resistance Change
Authors: Liou D. M. , Gong J. , Chen C. C.
Published: February 2005

A model based on the electromigration-induced resistance change was used to analyze the noise characteristics of aluminum thin-film resistors, and the 1/f
2 noise power spectrum was derived theoretically from the rate equation of the resistance change. Experiments were performed on samples stressed with a current density of 1 × 106 A/cm2 at 125°C for 50 hours. The measured noise indeed showed 1/f
2 noise and the results were analyzed quantitatively with the derived model.
New Package Cooling Technology Using Low Melting Point Alloys
Authors: Fukuoka Yoshitake , Ishizuka Masaru
Published: February 2005

This paper describes one of the new package cooling technology concepts using low melting point alloys in order to perform high density packaging. Two kinds of cooling alloy materials, Bi/Sn/In and Bi/Pb/Sn/In, whose melting points are less than 80°C and which are not expensive, were selected. Each experimental substrate sample was fabricated using greensheet technology on which a tungsten metallised heat resistor was formed. A kovar shell was attached to the back side of the substrate and filled with the low melting point alloy. The temperature distribution of the substrate was measured and it was confirmed that the substrate back surface temperature was fixed at the melting point for several minutes by thermal absorption while the alloy's phase changed. This new cooling technology is extremely useful for high-power circuit packages.
Selective Epitaxial Growth of AlGaAs by Atmospheric Pressure –MOCVD Using Diethylgalliumchloride and Diethylaluminiumchloride
Authors: Yamaguchi Ko-ichi , Okamoto Kotaro
Published: February 2005

Selective epitaxy of AlGaAs was carried out by atmospheric pressure-MOCVD using DEGaCl and DEAlCl. In the case of Al composition of 0 and 0.16, polycrystal deposition on SiO2 masks was drastically suppressed at the growth rate below 0.020 µm/min. Even, in case of high Al composition of 0.43 and 0.73, a high selectivity of the deposition could be realized as long as the growth rate was kept below 0.017 µm/min. The high selectivity of the deposition can be explained by reevaporation of the reactant species in the form of GaCl and AlCl on the masks. Extremely flat surfaces were also obtained for GaAs selective epilayers grown below substrate temperature of 750°C and growth rate of 0.02 µm/min. In case of Al0.16Ga0.84As selective growth, ridge growth appeared in spite of growth conditions of 0.02 µm/min and 730°C. It is proposed that the ridge growth is related with vapor-phase diffusion from mask areas.
ZnTe Growth and In Situ Gas Analyses in Low-Pressure MOVPE
Authors: Nhishio Mitsuhiro , Ogawa Hiroshi
Published: February 2005

Homoepitaxial layers of ZnTe have been grown by the low-pressure metalorganic vapor phase epitaxial method as a function of total pressure or substrate temperature. The growth rate of the epitaxial layer decreases with decrease in these growth parameters, and depends upon the substrate orientation. For the (110), (100) and (111)Te substrates, the activation energy associated with the growth rate is almost independent of the total pressure and substrate orientation. The in situ gas analyses, using the quadrupole mass spectrometer and ultraviolet spectrometer, were carried out in order to clarify the pyrolysis properties of the source materials.
Short-Pulse Generation in the Transient Raman Regime with a Parahydrogen Raman Laser
Authors: Higashii Takeshi , Tsunemi Akira , Nagasaka Keigo , Midorikawa Katsumi , Tashiro Hideo
Published: February 2005

Generation of Stokes pulses as short as 1 ns has been observed in the transient rotational Raman conversion of CO2 laser pulses with a multiple-pass Raman cell. The capability of producing pulses with energies up to 100 mJ in the 13–17 µm region was demonstrated. The experimental results were found to be consistent with theoretical predictions of the Stokes pulse width and the conversion efficiency in transient scattering.
F-Type Centers in Neutron-Irradiated AIN
Authors: Atobe Kozo , Honda Makoto , Fukuoka Noboru , Okada Moritami , Nakagawa Masuo
Published: February 2005

The production of point defects by neutron irradiation and thermal decay in sintered AIN polycrystal are investigated. The absorption band at 370 nm is observed after reactor neutron irradiation to a dose of 1016 n/cm2 (E>0.1 MeV). The defect corresponding to the band is tentatively assigned as an F-type center from the optical absorption and electron spin resonance.
X-Ray Photoelectron Spectroscopy Studies on Modified Poly(ethylene Terephthalate) Surfaces after KrF Laser Ablation
Authors: Kokai Fumio
Published: February 2005

The chemical structure of poly(ethylene terephthalate) (PET) surfaces modified by the irradiation of a KrF laser pulse are investigated by X-ray photoelectron spectroscopy. A decrease in oxygen-to-carbon atomic ratio and a change in bonding environment are induced by laser irradiation with a single laser pulse. The ablation is observed at fluences greater than ∼90 mJ/cm2. The observed features along the depth of a created surface are discussed in terms of preferential removal of carboxylic groups in PET molecules and surface oxidation after ablation.
Ferromagnetic (LaSr)MnO3 Films Deposited by RF Sputtering
Authors: Cho Jaekyong , Gomi Manabu , Abe Masanori
Published: February 2005

We prepared polycrystalline films of perovskite-type lanthanum manganese oxide La1-x
Sr
x
MnO3 (0≤x≤1) by RF diode sputtering, and investigated their structural, magnetic and magneto-optical properties. Crystalline films were easily grown during sputtering at relatively low substrate temperature (≥170°C). The films as crystallized in situ were poorer in crystallinity, and much smaller in saturation magnetization compared to bulk samples. By annealing the films in O2 atmosphere above 900°C, the saturation magnetization increased and approached the values of bulk samples. Magnetization was aligned perpendicular to the film plane when the film with x=0.21 (which was sputter-deposited in mixed gas of Ar:O2=9:1 on a GGG substate at 500°C) was annealed in air at 800°C. Faraday rotation F and ellipticity X increased at higher photon (h
v) energy range. F of the film annealed in O2 atmosphere at 900°C formed a peak at h
v=2.9 eV, reaching -2.6×104 deg/cm. X of the film reached -5.0×104 deg/cm at h
v=3.1 eV. The lanthanum manganese oxide film is a candidate for magneto-optical recording media using Kerr effect at short wavelength.
Steady-State Solution of Point-Defect Diffusion Profiles under Irradiation
Authors: Hashimoto Tsuneyuki
Published: February 2005

The solutions of the steady-state diffusion profiles of interstitials and vacancies given by Lam et al. are modified for application to high temperature irradiations, where equilibrium vacancies become significant. The effect of equilibrium vacancies on the diffusion profiles is similar to that of the homogeneously distributed sinks. Consequently, the modified solutions are obtained by altering the sink concentration expression.
Radical Emissions and Anomalous Reverse Flames Appearing in Upward-Increasing Magnetic Fields
Authors: Aoki Takashi
Published: February 2005

Upward-increasing magnetic fields of lower intensities increased flame dimensions and liberations of carbons, and decreased radical emissions, temperatures and a bluing tendency of the flame. These phenomena were opposite to those occurring in the upward-decreasing magnetic fields. The upward-increasing magnetic fields of stronger intensities caused an anomalous inverse burning, where the positions of the blue and the yellow-orange regions are reversed, and the highest temperature of the flame appeared at flame surfaces distant from the flame top. The above phenomena are ascribable to the fact that the flame shapes and the flow directions of combustion products, air and the flame were changed due to the magnetic forces originating from magnetic gradient fields, thereby resulting in changes in the mixing and the diffusion conditions.
White-Emitting Thin-Film Electroluminescence Devices with SrS Phosphor Doubly Activated with Rare-Earth Ions
Authors: Okamoto Shinji , Nakazawa Eiichiro , Tsuchiya Yuzuru
Published: February 2005

Thin-film electroluminescence (TFEL) devices with SrS-based phosphor layers have been investigated to obtain white emissions by mixing emissions of two different rare-earth activators, and new white-emitting phosphor layers, except for SrS:Pr, Ce, have been developed. SrS:Sm, Ce and SrS:Nd, Ho phosphor layers show white El-emissions, whose color coordinates correspond to points in the white area on the CIE chromaticity diagram. The EL emissions of SrS:Pr, Ce, SrS:Nd, Ce, and SrS:Ho, Ce phosphor layers are not found in the white area, but are close to the area. Luminance of the emissions, for devices driven with a sinusoidal voltage of 5 kHz, are 200–750 cd/m2, The three primary colors, red, green and blue, can be extracted from the emission of all these devices with color filters. Relative intensities of the three extracted colors are evaluated.
Gallium Arsenide Electroluminescent P-N Junctions Made by Close-Spaced Vapor Transport Epitaxy
Authors: Mimila-Arroyo Jaime , Navarro Gerardo , Pérez Gustavo , Castanedo Rebeca
Published: February 2005

Epitaxial gallium arsenide p-n junctions have been prepared using close-spaced vapor transport to grow an n-type layer on a p+ substrate. The diodes obtained show two well-defined conduction mechanisms. Using deep level transient spectroscopy a level located at E
c–E
t=0.74 eV having a concentration around 1014 cm-3 has been detected in the n region. Forward biased diodes show room temperature electroluminescence peaking at 1.4 eV.
Valence Band Electronic State of Transition-Metal Silicide TiSi2 Studied by Soft X-Ray Emission Spectroscopy (SXES)
Authors: Zhou Nansheng , Hirai Masaaki , Kusaka Masahiko , Iwami Motohiro , Nakamura Hatsuo
Published: February 2005

A soft X-ray emission spectrum (SXES) due to a transition from the valence band to an electron excited Si-L2, 3 level for TiSi2, a transition metal silicide, has shown a clear sharp peak at hν, photon energy, ∼98 eV. From the SXES study, it is concluded that a fair amount of the Si s-like electronic state is included in the upper half, especially at the Fermi edge, of the valence band density of state (VB-DOS) of TiSi2. This fact is in clear contrast to dominant proposals given so far, where it is claimed that the upper part of the VB-DOS of TMSi's is constructed only by electronic states due to transition metal(d)-Si(p) hybridization.
Preferentially Oriented Crystal Growth in Dynamic Mixing Process–An Approach by Monte Carlo Simulation–
Authors: Kiuchi Masato , Chayahara Akiyoshi , Horino Yuji , Fujii Kanenaga , Satou Mamoru , Kang Hee Jae , Beag Young Whoan , Kimura Yoshihide , Shimizu Ryuichi
Published: February 2005

Titanium nitride films produced by a dynamic mixing method have a preferential crystallographic orientation, and the orientation varies with the arrival ratio of the depositing elements. For this study, we performed a Monte Carlo simulation of the damaging process caused by nitrogen ion irradiation onto (111) and (100) planes of a TiN single crystal. The simulation predicts that in (100)TiN, N+ penetrates through the open channel, losing its kinetic energy mainly by electronic stopping, while N+ loses its kinetic energy mainly by nuclear stopping in (111)TiN, leading the crystal to be amorphous. The contribution of this dynamic mixing process to the development of preferred orientation is discussed.
A Simple Alternating Current Magnetometer of the Automatic Balancing Type
Authors: Ikeda Naoshi , Kohn Kay
Published: February 2005

An improvement of a Hartshorn type alternating current magnetometer is reported. The use of a dual channel oscillator, a two-phase lock-in amplifier and a personal computer enabled us to obtain a simple feedback system for automatic balancing of the bridge. The resolution of this system is about 3×10-7 emu of magnetic moment or higher at the field of 0.8 Oe in amplitude and 159 Hz in frequency.
Observation of Initial Growth Stage of Amorphous Si Film Deposited on 7×7 Superlattice Surface of Si(111) by Low-Energy Electron Diffraction
Authors: Shigeta Yukichi , Maki Kunisuke
Published: February 2005

The intensities of low-energy electron diffraction (LEED) were measured from Si films with various thicknesses (d) which had been deposited on a 7×7 reconstructed surface of Si(111) substrates maintained at 170°C. The intensity profile from Si films at d>60 Å gives a feature showing the formation of an amorphous phase. From ultrathin Si films with 5 Å<d<60 Å, two peaks were observed clearly at positions which correspond to the (0, 0) and (1, 0) rods in the Si(111) surface. This suggests that the Si film in the vicinity of the Si(111) substrate comprises interface layers with the some ordered structure. Some discussion is given on the interface layers, which are composed of two epitaxially grown grains. A normal stacking sequence of the diamond structure is formed in one grain and the reversed stacking sequence grows at the stacking fault layer on the preserved 7×7 structure in another grain.
Superresolution of FT-NMR Spectra by the Maximum Entropy Method and AR Model Fitting with Singular Value Decomposition
Authors: Uchiyama Takanori , Minamitani Haruyuki , Sakata Makoto
Published: February 2005

The complex maximum entropy method and complex autoregressive model fitting with the singular value decomposition method (SVD) were applied to the free induction decay signal data obtained with a Fourier transform nuclear magnetic resonance spectrometer to estimate superresolved NMR spectra. The practical estimation of superresolved NMR spectra are shown on the data of phosphorus-31 nuclear magnetic resonance spectra. These methods provide sharp peaks and high signal-to-noise ratio compared with conventional fast Fourier transform. The SVD method was more suitable for estimating superresolved NMR spectra than the MEM because the SVD method allowed high-order estimation without spurious peaks, and it was easy to determine the order and the rank.
Particle Simulation of Drift-Cyclotron Instability
Authors: Lee Jae Koo , Birdsall C. K.
Published: February 2005

The drift-cyclotron instability may occur in a collisionless Maxwellian magnetized plasma, driven by the free energy associated with a spatial density gradient normal to the magnetic field. Electrostatic particle simulations are used to study this instability with both species magnetized and treated fully nonlinearly. During the linear stage simulations show exponential growth in time over a few ion cyclotron periods, with the growth rates in fair agreement with a linear nonlocal theory, while the real parts of frequencies are not well resolved in the short growth period. The total electrostatic field energy reaches a peak of a few percent of the initial ion kinetic energy for most runs, with ωpi
2/ωci
2 and mass ratios ranging from 25 to 200. These simulation saturation levels are somewhat above those predicted by existing nonlinear theories. At the time of saturation, the phase space pictures of electrons and ions show bunching and density profile modification occurs.
Determination of Electron Energy Distribution Function of Plasmas by Digital Processing from Langmuir Probe Characteristic
Authors: Fujita Fumiyuki , Yamazaki Hatsuo
Published: February 2005

Electron energy distribution functions of plasmas were calculated by digital processing from Langmuir probe characteristics. The method used is based on the least squares priciple for fitting the experimental data to a polynomial curve, and performs the differential operation by a convolution of data with weighting functions. The computer program developed in accordance with this method was applied to the probe characteristics of positive column plasmas. The results were compared with the Maxwellian and Druyvesteyn distribution functions.
Anisotropy of Elastic Scattering of Low-Energy Electrons in Noble Gases
Authors: Ohya Kaoru , Mori Ichiro
Published: February 2005

The elastic differential cross sections of low-energy electrons with He, Ne, Ar, Kr and Xe atoms are investigated with the phase shifts obtained theoretically. The results show the forward scattering and the behavioral variation with the scattering angle for the Ramsauer gases (Ar, Kr and Xe), and the isotropic scattering for He and Ne.
Temperature, Density, and Perturber Dependences of Absorption of the 3.39 µm He–Ne Laser by Methane
Authors: Tsuboi Takao , Arimitsu Naoko , Ping Du , Hartmann Jean-Michel
Published: February 2005

We present an experimental and theoretical study of the absorption of the IR He–Ne laser (3.39 µm) by Ch4. Shocktube measurements were made for mixture of CH4 with Ar, N2, and O2 in wide density and temperature ranges. Calculations were made by using the available spectroscopic data on CH4 absorption lines. Comparison between experiments and calculations show that the theoretical predictions are accurate for all densities up to the temperature of 1200 K. At 2000 K, the calculations fail, probably due to insufficient knowledge of hot-band lines. Furthermore, the present study shows that mixture of CH4 with Ar, O2, and N2 lead to absorptions which are similar (within experimental error), as is confirmed by the theoretical model.
Additive Nitrogen Effects on Oxygen Plasma Downstream Ashing
Authors: Fujimura Shuzo , Shinagawa Keisuke , Nakamura Moritaka , Yano Hiroshi
Published: February 2005

Using an improved actinometry method, additive nitrogen effects on oxygen plasma downstream ashing have been studied. The ion current of the Langmuir probe and emission intensity change in OI(7774) and OI(8446) as a function of nitrogen mixing ratio showed that emission caused by dissociative excitation of oxygen molecules did not significantly influence the actinometry in our experiment. Thus, the actinometry measured accurate relative concentrations of atomic oxygen in the plasma by selecting XeI(4671) or XeI(4624) for the actinometer to OI(7774) and OI(8446) or by using ArI(7503) or ArI(7067) for the actinometer to OI(6258) and OI(4368). The change in the ashing rate and the relative concentration of atomic oxygen as a function of the nitrogen mixing ratio corresponded well, and both values at 10% nitrogen mixing were twice those with no nitrogen mixing. The activation energy was unchanged regardless of additive nitrogen. Therefore the role of nitrogen as the additive impurity gas is only to increase oxygen in the plasma.
A Simple Cylindrical Retarding Field Energy Analyzer
Authors: Fujii Yasuo , Ishiguro Eiji , Kitada Tadayoshi
Published: February 2005

A simple cylindrical retarding electron energy analyzer (CREA) with a retarding field was designed on the basis of a calculation of the potential distribution and the electron trajectories. A prototype analyzer was constructed and the performance was examined. The resolution obtained was about 0.3% at the FWHM at the electron energy of 500 eV, which was in fairly good agreement with the calculated resolution of 0.5%. The transmission efficiency of the CREA was about 30% at the electron energy of 200 to 500 eV. The Auger spectrum of a Ag sample measured with a modulation technique was very similar to a spectrum observed by a CMA.
Water Vapor Effects on Titanium Diffusion into LiNbO3 Substrates
Authors: Nozawa Toshinori , Miyazawa Hiroshi , Miyazawa Shintaro
Published: February 2005

This paper describes experimental studies on titanium diffusion into Z-cut LiNbO3 substrates as a function of water vapor content in the diffusion atmosphere of oxygen and argon. LiNbO3 crystal characteristics were found to depend mainly on water vapor content, while Ti-diffusion characteristics were found to be affected not only by water vapor content but also by the type of carrier gas. This study has important implications for the successful fabrication of Ti-diffused LiNbO3 waveguides; for oxygen carrier gas, a small amount of water vapor should be introduced, while for argon carrier gas, a medium amount of water vapor should be introduced.
Rotating CO2
- Centers in Coral and Related Materials
Authors: Miki Toshikatsu , Kai Ayako
Published: February 2005

Radiation-induced radicals in coral, single-crystal aragonite, synthetic calcite and calcium phosphates are studied by ESR at low temperatures. The isotropic ESR signal at g=2.0007, which is used for ESR dating of CaCO3, disappears below 200 K, and a spectrum with an anisotropic line shape is detected. The linewidth of the isotropic signal increases between 220 and 200 K with decreasing temperature. The g=2.0007 signal is attributable to rotating CO2
- ions.
Very-Low-Energy Electron Beam Lithography Using a Retarding Field
Authors: Ishii Kiyoshi , Matsuda Tadahito
Published: February 2005

This work explores the feasibility of very-low-energy electron lithography using a retarding field electron optical column and a self-developing resist. It is shown that the retarding field electron optical column has excellent focusing properties for a very-low-energy electron beam and permits focusing at energies as low as 20 eV. In addition, this study finds that poly (2-methylpentene-1 sulfone) (PMPS) is self-developed at exposures to energies of above 40 eV. Here, also a 0.6- µm line-and-space pattern is achieved using a 50-eV electron beam. It is demonstrated that the patterns produced by very-low-energy electron beam lithography exhibit excellent linewidth control.
Characterization of Indium Tin Oxide and Reactive Ion Etched Indium Tin Oxide Surfaces
Authors: Kuo Yue
Published: February 2005

ITO films, both before and after annealing, were characterized with various methods. The changes in film characteristics are discussed. RIE etching mechanisms for the unannealed ITO films in three reactive gases (CF2Cl2, CF3Cl, and CF4) and two diluent gases (N2 and Ar) were delineated by analyzing and comparing the surface ESCA data with the process results. For undiluted gases, indium is the major component left on the surface, and each gas has its own etch preference for different components. The addition of a diluent into the plasma may change the surface composition as well as the etching mechanisms. To increase the whole film etch rate, each component has to be etched off effectively.
Self-Aligned Microfabrication of Metal-Semiconductor Contacts by Projection-Patterned Excimer Laser Doping
Authors: Sugioka Koji , Toyoda Koichi
Published: February 2005

Self-aligned microfabrication of metal-semiconductor contacts by projection-patterned doping using a KrF excimer laser and SiH4 gas is demonstrated. Copper thin films with a linewidth as narrow as 2.35 µm are deposited selectively on the doped region by electroplating using a CuSO4 aqueous solution. In addition, Au thin films with a linewidth of 1.57 µm are also deposited selectively by electroless plating in an Au-24s aqueous solution. Various properties of the metal thin films deposited by the different plating conditions are discussed. Using the selective metallization process, nonalloyed ohmic contacts can be fabricated with a specific contact resistance as low as 4.95×10-6 Ωcm2, which is 1/150 of that of the conventional alloyed contacts.
Low Energy Focused Ion Beam System and Application to Low Damage Microprocess
Authors: Kosugi Toshihiko , Mimura Ryou , Aihara Ryuzo , Gamo Kenji , Namba Susumu
Published: February 2005

We have developed a low energy focused ion beam (FIB) system by employing retarding field optics. The system is equipped with a gas jet and is used for ion beam assisted etching or deposition. To evaluate the usefulness of low energy FIB, we have been investigating defects in GaAs induced by irradiation of low energy Ga+ FIB and Ar+ unfocused beams. Defets induced by irradiation at 300 K were observed even at a depth of >2000 Å, which is much deeper than the ion range. However, it was observed that the deep distribution was suppressed by irradiation at low temperature (100 K.
Influence of Chamber Pressure on Hydrogen Bonding Configurations in a-SiGe:H Films Prepared by Photo-CVD
Authors: De Abhijit , Ganguly Gautam , Ray Swati , Barua A. K.
Published: February 2005

Hydrogenated amorphous silicon-germanium (a-SiGe:H) thin films have been deposited by the process of mercury sensitized photo-CVD method from a mixture of silane and germane gases. The growth processes of a-Si:H and a-Ge:H films have been studied at different chamber pressures and from these data optimum pressures for the deposition of a-SiGe:H films have been selected. The variations of the electrical and structural properties of these films with optical band gap have been studied with films deposited at different chamber pressures. The properties of a-SiGe:H films have been found to be better at lower chamber pressure and the data is interpretated on the basis of changes in hydrogen bonding configuration with pressure.
Magnetic Shielding Effect of Ba2YCu3O7-δ Plates
Authors: Ohshima Shigetoshi , Okuyama Katsuro
Published: February 2005

The magnetic shielding effect of Ba2YCu3O7-δ, Cu and Fe-Ni plates was examined as a function of the frequency of applied ac magnetic field using magnetic heads. The effect of Ba2YCu3O7-δ plates was superior to that of Cu and Fe-Ni plates in the low-frequency (< 5 kHz) region at 77 K, while in the high-frequency (> 10 kHz) region, the effect of Ba2YCu3O7-δ plates was almost the same or slightly inferior to that of Cu plates. The shielding effect of Ba2YCu3O7-δ plates was strongly affected by the micro cracks and porosity of the samples. The magnetic shielding effect of Ba2YCu3O7-δ plates decreased rapidly with applied dc magnetic field, while the effect of Cu and Fe-Ni plates did not change with the application of dc magnetic field.
Local Magnetic Anisotropic Effects in Fe-B-Si Metallic Glasses
Authors: Murthy G. V. S. , Raju S. B.
Published: February 2005

Magnetic hysteresis studies were carried out on Fe78B13Si9 (2605S-2) and Fe79B16Si5 (2605S-3) for both as-cast samples and those after annealing for 2 hours at different temperature, viz., 373 K, 473 K, 573 K and 673 K. The coercivity was found to increase with annealing temperature almost similarly for both samples in the beginning. Maximum coercivity was obtained for the samples annealed at 473 K. Then the coercivity was found to decrease when annealed at 573 K and 673 K. The value for the sample annealed at 673 K was found to be even less than the as-cast value. Saturation magnetization of all the samples was determined using small samples in a high magnetic field. The observed changes in these parameters at different annealing temperature as compared with as-cast values are discussed on the basis of different effects taking place during the amorphous-to-crystalline transformation and consequent fluctuating exchange interactions and local magnetic anisotropy.
Crystal Growth during the Sintering of Ultrafine SiC Powders Containing Much Free-Si
Authors: Ando Yoshinori , Ohkohchi Masato
Published: February 2005

Ultrafine powders of SiC containing a large amount of free-Si, which had been prepared by a gas-evaporation method, were sintered at various conditions with the aid of amorphous boron. Surfaces of sintered bodies were examined by scanning electron microscopy (SEM) and X-ray diffraction. Different growth features due to asymmetry in the evaporation of free-Si were observed on the top and bottom surfaces of sintered bodies. Remarkable grain growth of platelike and polyhedral crystals of SiC was observed in the single sintering at high temperature under the existence of free-Si and with the aid of boron. By the multiple sintering of the identical specimen, the existing region of 6H-SiC and remaining free-Si was clarified versus the sintering temperature and the amount of boron addition.
Observation of a Visible Line Emission from RF and ECR Oxygen Plasmas
Authors: Sakamoto Yuichi , Kokai Hideki , Komuro Shuji , Uchiyama Tomoo , Kashiwagi Kunihiro , Morikawa Takitaro , Murayama Yoichi
Published: February 2005

Spatial distributions of 777-nm (3s5S-3p5P) emission from oxygen ECR (2.45 GHz) and RF (13.56 MHz) plasmas are observed near an electrode. For the ECR plasma, a peak in the emission near the resonance zone was observed under a certain pressure (4 × 10-3 Torr) accompanied by a decrease in the emission toward the electrode. For the RF plasma, an increase in the emission toward the electrode was observed.
Thin Film Monitoring with Ellipsometry in In-Line Processing Equipment
Authors: Hayashi Yasuaki
Published: February 2005

An ellipsometer for in-line monitoring has been developed. The construction is simple and it determines both the refractive index and thickness of a film in about 5 seconds through a simple and fast calculation method. The ellipsometer was set under an unloading chamber of in-line processing equipment and the optical alignment was adjusted with a simple method. For examination, SIN
x
films have been monitored. The results have been that the measurement was precise and the in-line monitoring of the film was successively performed.
Si/W Ratio Changes and Film Peeling during Polycide Annealing
Authors: Yoo Chue-san , Lin Tin-hwang , Tsai Nun-sien , Ijzendoorn Leo. J.
Published: February 2005

Tungsten silicide has found wide applications in VLSI device fabrications; nontheless, peeling has been a major problem in manufacturing. Adhesion of tungsten silicide films is strongly related to the film compositions, Si/W atomic ratios, which in turn can be altered by oxidation conditions. In this work, we investigated the tungsten polycide peeling mechanism and explored the causes for peeling. RBS, XRD and Auger were used to correlate the silicide adhesion to its composition changes due to oxidation. It is found that during the first oxidation of the polycide films, the silicon atoms in the silicide films are driven out of the silicide bulk toward both the surface and polysilicon-silicide interface. Bared oxidized polycide films would peel upon further oxidation. The peeling mechanism is illustrated. Solutions to the film peeling prevention will also be proposed.
Novel Process for Direct Delineation of Spin on Glass (SOG)
Authors: Imai Akira , Fukuda Hiroshi , Ueno Takumi , Okazaki Shinji
Published: February 2005

Some types of spin on glass (SOG) are radiationchemically sensitive and act as negative-tone resist for electron beam (EB) exposure. Using direct EB writing, 0.2 µm line and space (L/S) patterns are obtained with a 400 µC/cm2 EB dose at an acceleration voltage of 30 keV. Although this material has high-resolution capability, the sensitivity is too low for practical resist applications. In order to improve sensitivity, an acid catalyzed system is introduced. 0.3 µm L/S patterns are delineated with an EB exposure dose of 0.7 µC/cm2 using a SOG-based chemically amplified material. This radiationchemically sensitive characteristic of SOG can be applied to a bi-layer resist system.
Study on Reaction Mechanism of Aluminum Selective Chemical Vapor Deposition with In-situ XPS Measurement
Authors: Kawamoto Hideaki , Sakaue Hiroyuki , Takehiro Shinobu , Horiike Yasuhiro
Published: February 2005

Aluminum (Al) films have been deposited selectively on Si at a substrate temperature from 270 to 330°C under 1 × 10-3 Torr employing dimethylaluminum hydride (DMAlH). The experiments were carried out in a reaction chamber connected to an X-ray photoelectron spectroscopy (XPS) analyzer. The origin of selectivity was studied by in-situ XPS analysis, dopant dependency and surface treatments. The selectivity was independent of the dopant type and its concentration in Si substrate. In-situ XPS measurement revealed that the Al-hydrogen (H) bond was broken only on the Si surface. No Al film grew on the Si surface subjected to Ar+ ion bombardment, while the Si surface exposed subsequently by hydrogen radicals was allowed to deposit the Al film. Eventually, it is considered that hydrogen (H) and/or fluorine (F) which terminates the Si surface after dipping in HF solution reacts with H atoms and methyl group in DMAlH, leading to the selective deposition of Al. Al did not grow on SiO2 and Al2O3 surfaces because of the easy oxidation of Al due to the reaction of Al with oxide surfaces. Al could deposit on the TiN surface after the native oxide was reduced by hydroden radicals.
SiO2/Si Interfaces Studied by STM and HRTEM (II)
Authors: Niwa Masaaki , Onoda Minoru , Matsumoto Michikazu , Iwasaki Hiroshi , Sinclair Robert
Published: February 2005

The morphology of the interfaces between Si(001) and thermal SiO2 grown by several oxidation conditions has been studied to compare the roughness of the interfaces observed, in particular, by STM and HRTEM. For STM observations, hydrogen-terminated Si surfaces were prepared by means of HF dipping. Dry oxide interfaces had irregularly distributed bumplike protrusions; in contrast, wet oxide interfaces revealed relatively flat features except for large undulations which localized sparsely. These morphological features ran along in the <110> direction. It was difficult to obtain a reproducible STM image for dry oxide interface. The interface roughness of both wet and dry oxides resulted in higher values for the STM observation in comparison with HRTEM results. During the HRTEM observation, high-energy electrons damage the sample and reduce the oxide thickness by roughening the interface, especially in the wet oxide samples.
Electron-Beam Testing of Microwiring Substrates
Authors: Brunner Matthias , Schmid Ralf , Schmitt Reinhold , Lischke Burkhard , Wörner Mireille , Bergh Nikola Then
Published: February 2005

The miniaturization of microwiring substrates which are used for high-density chip packaging imposes increasing problems on electrical testing. Mechanical probes fail to contact pads reliably in the 50 µm range and are limited to a fixed pad configuration. An electron-beam test system has been developed to overcome these problems. It uses CAD data for flexible beam positioning within a 10 cm × 10 cm field. An electron probe with a spot size of 40 µm is used for charging networks and reading pad voltages. The system has already demonstrated its operation by detecting shorts and opens on a limited number of substrates which were rejected as defective by a mechanical prober during the final test of the current production.
Fabrication of Free-Standing Single-Crystal Silicon Nanostructures for the Study of Thermal Transport and Defect Scattering in Low Dimensional Systems
Authors: Potts A. , Williams D. A. , Young R. J. , Blaikie R. J. , McMahon R. A. , Hasko D. G. , Cleaver J. R. A. , Ahmed H.
Published: February 2005

Free-standing wire samples have been fabricated that enable low dimensional conducting wires to be examined by transmission electron microscopy (TEM). These structures have been fabricated using a combination of gas-assisted ion beam etching and electron beam lithography, and have cross-sectional dimensions between 70 nm and 1 µm, and lengths of up to 50 µm. The free-standing wires have been examined by TEM before and after ion implantation and annealing. The results indicate that no extended defects are created in the wires, even for high doses (1016cm-3) or high beam energies (>50 keV). The reason for this is not fully understood. In addition, the fabrication process has been extended so that low temperature electrical measurements can be performed on the TEM samples. In this way it is hoped eventually to study the role of specific crystalline defects in limiting the electronic and phonon transport.
Aging Reduction of ZnS Films Using Chopping Technique
Authors: Puri Vijaya R. , Puri Ravinder K. , Karekar Ravi N.
Published: February 2005

This paper describes changes in the refractive index of chopped and non-chopped ZnS films when exposed to air, moisture and heat ambients as measured by an ellipsometer. The films were deposited on a glass substrate using the vacuum evaporation technique. Film thicknesses from 300 Å to 1400 Å are reported here. The chopping technique has been found successful in reducing the aging of ZnS films. The changes in the refractive index are found to be thickness-dependent and this dependence is considerably reduced in chopped films. Chopping seems to increase the homogeneity of the films. The changes in the refractive index are interpreted as the effects of various processes.
Ultralow Resistivity in Langmuir-Blodgett Heterofilms of Much Less than the Metal Resistivity and Ultrahigh Current Density
Authors: Hino Taro , Kushida Masahito
Published: February 2005

Ultralow resistivity in Langmuir-Blodgett (LB) heterofilms of much less than the metal resistivity was briefly reported in the previous paper, and such remarkable characteristics seem to be due to the two-dimensional potential well with electron gas generated in the LB heterofilms. In the present paper, detailed data of the ultralow resistivity are described with data related to temperature (room temperature ∼75°C) and ambient air pressure. The minimum resistivity of 4.0×10-12Ω·cm was measured; furthermore, an ultrahigh current density of 2.0×106 A/cm2 was observed.
Surface Modification of Polytetrafluoroethylene Films by Discharges
Authors: Kusabiraki Minoru
Published: February 2005

A triode glow discharge system was used for the plasma treatment of polytetrafluoroethylene (PTFE) films and the formation of plasma polymerized hexamethyldisiloxane (PPHMDS) films on PTFE films. The nitrogen plasma increased the surface tension of the PTFE films to about 40 dyn/cm by applying an rf voltage to the substrate electrode. The contact angle of water on the PPHMDS films with the rf voltage was changed to 40°∼90° by corona discharge exposure for 30 s at 6 kV. This reduction is due to the decarbonization and the oxidation of PPHMDS films.
High Resolution Time-of-Flight Electron Spectrometer
Authors: Uehara Yoichi , Ushiroku Tadamasa , Ushioda Sukekatsu , Murata Yoshitada
Published: February 2005

We have developed a high resolution time-of-flight (TOF) electron spectrometer. To attain the high resolution, a new high speed electron gate was developed for precise flight time measurement. The time resolution of this gate improves for slow electrons and it is a few hundred picoseconds for an electron beam of a few eV. To evaluate the performance of the TOF spectrometer, we have measured the energy distribution of electrons emitted from NEA GaAs irradiated by a 820 nm GaAlAs laser with a 60 ps pulse width. The spectrometer including the gate works as intended and the highest resolution achieved is 3 meV for the electron flight energy of 3 eV.
A Study of Particle Confinement Using Skin Radiative Approximation Method in JT-60 Tokamak
Authors: Koide Shinji , Shimizu Katsuhiro , Sugiyama Takashi , Nishitani Takeo
Published: February 2005

In order to analyse the particle behavior of hydrogen plasma based on the measurement data of Hα line radiation, `skin radiative approximation method' has been used. The characteristics of particle confinement in the JT-60 tokamak are investigated by this model. This method will be applicable to large tokamak like JT-60, JET and TFTR.
The Dipole Moment of the B'0+ State of IBr Determined through the Line Shape Analysis of the Stark Modulation Spectrum
Authors: Takei Taka-aki , Watanabe Akiyoshi , Sato Yoshi-ichi , Amako Yoshito
Published: February 2005

The dipole moment of the B'0+ state of IBr has been determined from the line shape analysis of the Stark modulation spectra of the B'0+←X
1Σ+ transition. It is -0.056±0.017 D at the v'=11 level of IBr81 and -0.033±0.034 D at the v'=15 level of IBr79. The magnitude of dipole moment of the B'0+ state is considerably smaller than that of the ground-state dipole moment (0.726 D), and its direction is opposite to that of the ground-state one.
A New Angular Shearing Interferometer for Collimation in the Nanoradian Range
Authors: Tanaka Mitsuru , Nakayama Kan
Published: February 2005

A new compact polarization laser angular interferometer for precision collimation of a mirror in the nanoradian range is described with an analytical treatment and an experimental verification of its performance. The phase of the optical fringe is proportional to the angular deflection of the object mirror. The angular shearing in two interfering laser beams modulates its amplitude so sharply that it enables determination of a particular optical fringe out of a number of periodic fringes. Ray tracing and Gaussian beam treatment can describe the mechanism of the modulation and explain the experimental behavior and predict some important features of the interferometer required for other precision applications.
Thermally Stimulated Discharge of Au/LB/Air-Gap/Au Structures Incorporating Cadmium Arachidate Langmuir-Blodgett Films
Authors: Iwamoto Mitsumasa , Sasaki Tohru
Published: February 2005

We fabricated cells having the structure of Au/LB/air-gap/Au in order to eliminate the influence of both the inherent oxide layer formed on electrodes and metallic wires through the LB film. We then investigated the dynamic behavior of constituent molecules in the LB film by measuring the thermally stimulated current (TSC) in a short-circuit condition while the cell was heated at a constant heating rate. TSC peaks were observed at temperatures of -190°C, -40°C and about 90°C, and these peaks were assigned to the relevant discharge mechanism relating to the thermal relaxation of molecules in the LB film. Finally, it was concluded that TSC peaks were obtained even when the number of deposited layers was one.
Effect of Ar Pressure on the Sputter Deposition of Tungsten/Carbon Multilayers
Authors: Nagata Hiroshi , Seki Shoji
Published: February 2005

Tungsten/carbon multilayers were formed using rf magnetron sputtering at various Ar gas pressures. With decreasing Ar gas pressure, the reflectivity of the multilayers increased and smooth interfaces were observed. The growth of amorphous like W films proved to be important in reducing the interfacial roughness.
Long Plasma Production by a Radio-Frequency Discharge between Dielectric-Covered Parallel Electrodes
Authors: Nonaka Shigehiko
Published: February 2005

A very long plasma (1.5 meters) was confirmed to be produced by a radio-frequency (28 MHz) discharge between long dielectric-covered electrodes. The properties are: (1) the plasma number density drastically decreases at gas pressures below 15 Pa due to the shifting of the main discharge region toward the exterior near the electrode edges, (2) this density becomes maximum at the tip of the long electrodes and (3) becomes uniform within a narrow electrode width at intermediate pressures around 10 Pa. These properties were well explained qualitatively using the transmission line and ambipolar diffusion theories.
Accelerated Motion of a Metal Ring by Discharges with a Dielectric Substance
Authors: Murakami Hiroyuki
Published: February 2005

After a teflon plate superimposed on top of a glass plate is rubbed with cloth, it is held several centimeters away from the glass plate and a metal ring is put on the glass plate. The metal ring then begins to rotate on the glass plate by intermittent discharges between the teflon plate and the ring surface. The mechanism of acceleration of the metal ring is found to be the ring receiving the driving power by the Coulomb force accompanying the intermittent discharges between the teflon plate and the ring surface. The acceleration of the metal ring is measured by taking photographs of the rolling state of the metal ring.