bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration-Level Characteristics for Iron-Doped Lead-Zirconate-Titanate Ceramic
Authors: Hirose Sadayuki Takahashi
Published: February 2005

Vibration-level characteristics for Fe-doped lead-zirconate-titanate ceramic were studied using the constant current driving method. It was found that mechanical Q was markedly decreased with increasing vibration level, accompanying a lot of heat generation. The other electromechanical characteristics were slightly changed. The heat generation was found to decrease with increasing Fe doping concentration up to ∼2 at.%, and was found to show a minimum for lead-zirconate-titanate with the basic composition close to the morphotrophic phase boundary. It was assumed that the heat generation was mainly caused by ferroelectric domain wall hysteresis loss.
Ultrasonic Butt Welding of Large Metal Plates by Shifting Welding Tip Driving Position
Authors: Tsujino Jiromaru , Ueoka Tetsugi , Watanabe Ichiro , Ogawa Masato , Masakazu Hirasawa Masakazu Hirasawa , Yuki Fujita Yuki Fujita
Published: February 2005

Ultrasonic butt welding of large metal plates by means of shifting the welding tip driving position at regular intervals is studied. The ultrasonic vibration source used has eight 15 kHz bolt-clamped Langevin-type lead-zircon-titanate (PZT) transducers of 60 mm diameter and is driven by a 50 kW static induction thyristor power amplifier. Aluminum plate specimens of 6 mm thickness and 100 mm to 400 mm width are joined successfully end-to-end with almost equal weld strength along the weldment. The input power required for aluminum plates is about 2.2 kW/cm2. The power required by one welding process for aluminum and copper plate specimens of 40 mm width is 4 kW/cm2.
Pressure Distribution for Piezoelectric Extracorporeal Shock Wave Lithotripsy
Authors: Yanagida Yuji , Nobuyuki Iwama Nobuyuki Iwama , Kiyoshi Okazaki Kiyoshi Okazaki
Published: February 2005

The objective of this study is to develop a safer and more effective extracorporeal shock wave lithotripter. The first stage of the study shows the sound pressure field of the shock wave made by an ECHOLITH ESL-500A. The sound pressure distribution is in a ring configuration on a 60 mm plane in front of the focal plane. As the plane approaches the focal plane, the sound pressure relatively increases at the cross point with the axis of the transducer and decreases at the ring. The focal zone is 2.5 mm×16.1 mm at 60 V driving voltage and 1.8 mm×14.2 mm at “INTENSITY 2.” In the next stage we propose a method for changing the field by electronic driving control of each piezoceramic element for effective therapy. The focal zone can be changed from 3.1 mm×19.1 mm to 3.9 mm×32.4 mm at 60 V driving voltage with this method. These focal zones are calculated by means of computer simulation.
Crack Measurements by Laser Ultrasonic at High Temperatures
Authors: Hidetoshi Nakano Hidetoshi Nakano , Satoshi Nagai Satoshi Nagai
Published: February 2005

A noncontact optical system for generation and detection of ultrasound is described. A confocal Fabry-Perot interferometer combined with a multimode optical fiber is used to reconstruct ultrasound images on a sample with a rough surface. The optical fiber is automatically adjusted to optimal positions for effective collection of scattered light from the sample. The confocal Fabry-Perot interferometer provides sensitive detection independent of surface roughness. The system is applied to a fatigue test sample, with which a conventional interferometer has poor sensitivity because of irregularities on the sample surface. The 2D profiles of the fatigue crack are successfully obtained at temperatures up to 1000°C. The crack length estimated from the profile agrees well with that measured using an optical method.
X-Ray Photoacoustic Spectroscopy of ZnO Thin Film
Authors: Toyoda Taro , Masujima Tsutomu , Ando Masami
Published: February 2005

The hard X-ray photoacoustic spectrum of ZnO thin film has been obtained in the EXAFS (extended X-ray absorption fine structure) region using synchrotron radiation. It is shown that information on EXAFS is included in the X-ray photoacoustic signal intensity and phase spectra which reflect the heat production processes in ZnO thin film. However, the results showed that the increases and changes in the photoacoustic signal intensity were different from those of the photoacoustic signal phase in the EXAFS region.
Spatial Distribution of EL2 in GaAs Wafer Determined by Photoacoustic Spectroscopy
Authors: Fukuyama Atsuhiko , Ikari Tetsuo , Kouji Maeda Kouji Maeda , Koji Futagami Koji Futagami
Published: February 2005

Photoacoustic (PA) measurements were carried out at 95 K for semi-insulating (SI) GaAs. A broad peak at 0.92 eV and humps in the higher-energy region are observed. Onsets of the humps are at 1.04 and 1.25 eV. Among these structures in the PA spectra, the broad peak at 0.92 eV is partly photoquenched upon illumination of a secondary light (hν=1.12 eV) and thermal recovery occurs after heating to around 150 K. The spatial profiles of this photoquenching along the wafer diameter show a W-shaped distribution. These results indicate that the quenching component of the peak at 0.92 eV in the PA spectra is due to nonradiative recombination of electrons excited from the EL2 level to the Γ-conduction band minimum. The electron transitions involving the EL2 level can be resolved by the PA measurements for the first time.
Growth and Characterization of In0.83Ga0.17As0.39P0.61 Layers by Liquid-Phase Epitaxy Using Erbium Gettering
Authors: Wu Meng-Chyi , Tu Cheng-Ming Chiu
Published: February 2005

The Er-doped InGaAsP epitaxial layers with a wavelength of 1.1 µm lattice-matched to InP have been grown by liquid-phase epitaxy. When the Er amount doped in the InGaAsP growth solution is lower than 0.21 wt%, it usually has a fairly shiny, smooth surface morphology and a flat interface between epitaxial layer and substrate. By the wavelength-dispersive-X-ray-spectrometry analysis, we find the Ga solid composition maintains the same as that in the undoped layer, while the As solid composition decreases linearly with increasing Er wt%. The lattice mismatch between InGaAsP layer and InP substrate also decreases linearly with the Er wt% in the growth solution. It may be due to the formation of microparticles of Er-rich compounds ErAs. All the Er-doped samples still exhibit n-type conduction, but its electron concentration decreases with increasing Er wt% and is one to two orders of magnitude lower than those of undoped layers. By the photoluminescence (PL) measurements at various temperatures and excitation levels from the undoped InGaAsP layers, we identify the three peaks associated with the near-band-to-band, shallow- and deep-donor-to-acceptor-pair transitions. However, the deep- and shallow-donor-to-acceptor recombination peaks will sequentially disappear with increasing Er wt% for the Er-doped layers. As the Er amount is above 0.54 wt%, only the near-band-to-band peak dominates the PL spectra and exhibit a full width at half maximum of 9.3 meV. These results can be attributed to the donor gettering in the presence of Er. In addition, the PL peak wavelength decreases linearly with increasing Er wt% due to the variations of solid composition and lattice mismatch in the Er-doped quaternary layers.
Monte Carlo Study of Charge Injection Transistors (CHINTs)
Authors: Akeyoshi Tomoyuki , Maezawa Koichi , Masaaki Tomizawa Masaaki Tomizawa , Takashi Mizutani Takashi Mizutani
Published: February 2005

Self-consistent Monte Carlo simulation of the characteristics of charge injection transistors (CHINTs), with special focus on the bias voltage and the channel length dependences of these characteristics, shows that the transconductance of CHINTs increases with increasing collector voltage until the leak current becomes extremely high. Simulation also reveals that the area associated with real-space transfer (RST) is about one-third of the channel, suggesting that CHINTs can operate faster than conventional metal-insulator-semiconductor field-effect transistors (MISFETs). We also investigated the number of electrons that transfer from each valley for two different band configurations and found that RST from the L-valley in GaAs dominates even though the energy level of the L-valley is greater than the heterobarrier height.
In Situ Ellipsometric Observations of the Growth of Silicon Thin Films from Fluorinated Precursors, SiFnHm (n+m≤3)
Authors: Akasaka Tetsuya , Araki Yuhzo , Masami Nakata Masami Nakata , Isamu Shimizu Isamu Shimizu
Published: February 2005

The growth of silicon thin films fabricated from fluorinated precursors SiF
n
H
m
(m+n≤3), was investigated for the first time by in situ ellipsometric observation. Specific dependencies were recognized of the ellipsometric trajectories in the (Ψ, Δ) plane on chemical species used as the precursors. Under certain film preparation condition wherein the structures formed depend greatly on parameters such as the substrate temperature and the substrate material, the film structure was altered from amorphous to polycrystalline or epitaxial. The ordering of the structure was gradually improved with an increase in the thickness. Under the other condition, µ-crystalline films with columnar texture were fabricated independently of substrate temperature or material.
Optical Constants of ZnSexTe1-x Ternary Alloys
Authors: Shunji Ozaki Shunji Ozaki , Sadao Adachi Sadao Adachi
Published: February 2005

The methods for calculation of the various optical constants in semiconductors are discussed, and results for ZnSe
x
Te1-x
ternary alloys are presented. The model used here is based on an interpolation scheme, and the effects of alloy composition are properly taken into account in the calculation. The present model reveals distinct structures in the optical spectra at energies of the E
0, E
0+Δ0, E
1, E
1+Δ1 and E
2 gaps. The optical constants and properties considered here are the complex dielectric constant (ε=ε1+iε2), complex refractive index (n
*=n+ik), absorption coefficient (α) and normal-incidence reflectivity (R).
GaAs Schottky Diodes with Ideality Factor of Unity Fabricated by In Situ Photoelectrochemical Process
Authors: Okumura Tsugunori , Shin-ichi Yamamoto Shin-ichi Yamamoto , Michiko Shimura Michiko Shimura
Published: February 2005

Schottky contacts to n-GaAs have been fabricated by means of a photoelectrochemical process in which in situ anodic etching of the substrate surface was performed in the same electrolytic solution as for electroplating of metals (Ni, Au, Sn and Pb). Measurement of the cyclic voltammogram was helpful in determining the applied voltages for in situ etching as well as metal deposition, and thus in fabricating good Schottky contacts reproducibly. The ideality factor (n value) of the fabricated diodes was unity for the substrate with an electron density of 2×1016 cm-3. The values of Schottky barrier heights determined by means of the I-V and C-V methods were in close agreement, and the chemical trend was clearly observed.
77 K Operation of Amorphous Si/Si Heterojunction Bipolar Transistors
Authors: Jiang Zheng , Jing Wu , Tongli Wei , Yian Wang , Wang Shu Wang Shu , Tong Qinyi Tong Qinyi
Published: February 2005

The low-temperature characteristics of current gain H
FE in amorphous emitter silicon heterojuntion bipolar transistors are studied. Current gain H
FE falls with decreasing temperature and increasing base concentration N
B at both room temperature and low temperatures. H
FE increases with increasing applied voltage V
BC at low-temperatures due to the low-temperature avalanche multiplication effect in the collector-base junction. It is concluded finally that the values of H
FE of this device at low temperatures are adequate for most digital applications.
Properties of BaPb1-xBixO3 as Observed in Single-Crystal Thin Films
Authors: Minoru Suzuki Minoru Suzuki
Published: February 2005

The resistivity, low-field Hall coefficient, optical transmission,
reflectivity, and upper critical field have been measured for BaPb1-x
Bi
x
O3
single-crystal thin films as a function of Bi content x.
It is found that the semiconductive temperature dependence
of resistivity, which evolves as x increases from 0.25,
is intrinsic to the BaPb1-x
Bi
x
O3 system. When
x exceeds 0.3, the resistivity abruptly increases and the
superconductivity
disappears. These changes are accompanied by a change in the
sign of the Hall coefficient. Based on these experimental results, a
systematic change of the electronic structure of the BaPb1-x
Bi
x
O3 system is
discussed. Furthermore, various physical properties of the BaPb1-x
Bi
x
O3
system are also derived based on a simple assumption.
Preparation, Processing and Tunneling in YBa2Cu3O7-δ-Pb Native-Barrier Structures
Authors: Frangi Francesca , Dwir Benjamin , James Jonathan H. , Andrea Gauzzi Andrea Gauzzi , Davor Pavuna Davor Pavuna
Published: February 2005

We have developed a procedure for the preparation of small (40×40 µm2) window-type YBa2Cu3O7-δ-Pb junctions with YSZ insulator and native tunnel barrier. We present the patterning technique of the two electrodes based on photolithography and wet etching. The nature of the barrier is found to be semiconducting. The tunneling measurements show gap-like feature of YBa2Cu3O7-δat 8.5 meV and some additional features related to Pb and YBa2Cu3O7-δphonon spectra.
Electron Spin Resonance in an Intermedate Valent Ytterbium Compound YbCuAl
Authors: Tien Cheng , Yu Jiag-Tsu , Duh Horong-Mo
Published: February 2005

The electron spin resonance (ESR) spectra in the mixed-valence compound YbCuAl have been observed between 4 K to 77 K. The temperature dependence of linewidths shows a clear anomaly around 40 K. Above 42 K, g=g
s=2.0023. Below 10 K, enormous g-shifts are observed. The properties of ESR spectra in YbCuAl can be qualitatively described by the s-f mixing model.
Second-Harmonic Generation and Relaxation in Polyurea Thin Films Prepared by Vapor Deposition Polymerization
Authors: Hikita Masayuki , Sinichi Yamada Sinichi Yamada , Teruyosi Mizutani Teruyosi Mizutani
Published: February 2005

Aromatic polyurea thin (PU) films were fabricated by means of coevaporation of 4,4'-diphenylmethane diiso-cyanate (MDI) and either 4,4'-diamino diphenyl methane (DDM) or 4,4'-diamino diphenyl ether (DDE). For the two PU films, second-harmonic generation (SHG) caused by corona poling and the subsequent isothermal decay were investigated. The second-order nonlinear coefficient d
33 was estimated to be 5.3 and 6.3 pm/V for PU(DDM) and PU(DDE), respectively, and proved to exhibit almost no decay with time up to 2000 h. It was also found that annealing prior to the poling process caused no additional increase of SHG. This result was interpreted in terms of increase in the packing density of molecules, leading to suppression of the molecular orientation. PU films containing excess residual isocyanate groups showed a large SHG decay to about 60% of the initial value within 10 min. It was concluded that the residual isocyanate groups in as-deposited PU films greatly affects the behavior of SHG relaxation.
Intrinsic Transmission Loss of Polycarbonate Core Optical Fiber
Authors: Tomoyoshi Yamashita Tomoyoshi Yamashita , Kensuke Kamada Kensuke Kamada
Published: February 2005

Intrinsic transmission loss of polycarbonate (bisphenol A-type) optical fiber (PC-POF) was experimentally determined by investigating three intrinsic loss factors: electronic transition absorption (ETA), molecular vibration absorption (MVA) and light scattering caused by thermal dielectric fluctuation. The intrinsic transmission losses for optical windows are 224 dB/km at 764 nm and approx. 166 dB/km at 650-656 nm. The intrinsic ETA loss is large in the region of short wavelength, hence it is suggested that the PC-POF yellows for white light transmission. The optical anisotropic parameter of polarizability for PC is much larger than that of polymethylmethacrylate (PMMA). The intrinsic scattering loss of PC-POF results almost entirely from the anisotropic scattering caused by the strong optical anisotropy of this polymer. Present transmission loss of PC-POF is much larger than the estimated intrinsic transmission loss because of the large excess loss arising from extrinsic loss factors. The PC-POF has the potential for low transmission loss equal to that of the PMMA-POF, if it is optically purified.
Positron Annihilation in Vitreous Silica Glasses
Authors: Akira Uedono Akira Uedono , Shoichiro Tanigawa Shoichiro Tanigawa
Published: February 2005

The annihilation characteristics of positrons in vitreous silica glasses (v-SiO2) were studied by measurements of two-dimensional angular correlation of positron annihilation radiations and positron lifetime spectra. From the measurements, it was found that positrons and positronium (Ps) atoms mainly annihilate from trapped states by vacancy-type defects in v-SiO2. For v-SiO2 specimens with cylindrical porous structures, annihilations of Ps with anisotropic momentum distributions were observed. This fact was attributed to the momentum uncertainty due to localization of Ps in a finite dimension of pores. This investigation showed possibilities for the detection of microstructures in v-SiO2 by the positron annihilation technique.
Tuning of a Surface Acoustic Wave Resonator Formed of Lithium Tetraborate Substrate Combined with Piezoelectric Ceramic Element
Authors: Hikita Kazuyasu , Suetsugu Takumi , Iizuka Hiroyuki , Yanagida Masaru Miyayama
Published: February 2005

Tuning of resonant characteristics, especially of resonant frequency, was studied on surface acoustic wave resonator, which was formed on a lithium tetraborate substrate and adhered to a poled piezoelectric ceramic element. The resonant frequency was tunable when a electric field (up to 1.5 kV/mm) was applied to the piezoelectric element. The magnitude of resonant frequency tunining was about 600 ppm, so that the temperature coefficient of resonant frequency change could be tuned to be constant or almost zero ppm/°C over the experimental temperature range between 0 and 75°C. The mechanism of tuning is considered to be that the distance between interdigital electrodes on the resonator was changed as the piezoelectric ceramic element was actuated and deformed with the application of electric field.
Local Etching Effect of Fine Gold Particles Deposited on Graphite
Authors: Hiroyuki Watanabe Hiroyuki Watanabe
Published: February 2005

The etching effect of fine gold particles evaporated on a graphite surface was investigated in this study. Gold particles with diameters around 2-3 nm deposited on graphite coagulate to form 10-100 nm-diameter particles during annealing at about 400°C. Furthermore, at the same time, it was found that the coagulation was accompanied by etching of the graphite substrate. For highly oriented pyrolytic graphite (HOPG), the same phenomenon was observed. On the other hand, no etching phenomenon was observed for a diamond surface. The oxidation reaction of graphite at the interface between gold particles and graphite by residual gas molecules in vacuum is greatly enhanced by the catalytic effect of gold particles.
Secondary Electron Emission from Hydrogen-Implanted Graphite with Real Depth Profile of Hydrogen
Authors: Ohya Kenji Nishimura
Published: February 2005

An experimental hydrogen depth profile is applied to a Monte Carlo simulation of secondary electron emission from hydrogen-implanted graphite. Due to hydrogen implantation, the secondary electron yield increases but the electron backscattering coefficient does not clearly change. Through thermal annealing of the specimen at a temperature higher than 600°C, the secondary electron yield returns to that of a clean graphite without implantation.
Dynamic Observation of Ag Desorption Process on Si(111) Surface by High-Temperature Scanning Tunneling Microscopy
Authors: Sato Tomoshige , Sueyoshi Takashi , Shin-ichi Kitamura Shin-ichi Kitamura , Masashi Iwatsuki Masashi Iwatsuki
Published: February 2005

The dynamical isothermal desorption process of Ag adsorbed on a Si(111) surface kept at about 600°C was observed by means of high-temperature scanning tunneling microscopy (HT-STM). The desorption of Ag caused a transition from the √3×√3-Ag phase to the 3×1-Ag phase having a lower Ag coverage, followed by another transition to the 7×7 phase. In the respective phase transitions, the produced phases extended from steps and domain boundaries. The number of Si atoms moved is discussed for the case of the phase transition from the 3×1-Ag structure to the 7×7 structure.
Scanning Tunneling and Atomic Force Microscopy of T4 Bacteriophage and Tobacco Mosaic Virus
Authors: Imai Kensaku , Yoshimura Kosei , Tomitori Masahiko , Nishikawa Osamu , Kokawa Ryouhei , Yamamoto Mitsuhiko , Kobayashi Masato , Ikai Atsushi
Published: February 2005

Bacteriophage T4 and tobacco mosaic virus were imaged by scanning tunneling microscopy after metal coating of the specimens and by atomic force microscopy without coating, and their topographies were examined. A metal coating approximately 5 nm in thickness assured easy and reproducible imaging of samples but obscured their detailed structural features. AFM gave a better resolution on this scale, revealing the presence of tail fibers 2 nm in diameter of T4 phage, which is the best resolution so far reported for isolated biological structures. Sample topographies were in good agreement with the results of previous electron microscopic analysis.
Scanning Tunneling Spectroscopy of Nanofeatures on Silver-Selenide Surface
Authors: Yasushi Utsugi Yasushi Utsugi
Published: February 2005

Scanning tunneling spectroscopy (STS) was performed to characterize nanofeatures on silver-selenide (Ag-Se) surface chemically modified by scanning tunneling microscopy (STM). Differential conductivity and gap-modulation images of the topologically modified surface show no structures, verifying no accumulation of Ag ions and chemically homogeneous surface. Moreover, current-voltage characteristics show that the Ag-Se surface is semiconductive. These characteristics change with the period of application of bias voltage, revealing the dynamical movement of Ag ions; lateral movement on the surface and migration into the matrix. These results suggest that these methods are powerful for chemically analyzing the fabricated nanofeatures.
Possibility of Observing Spin-Polarized Tunneling Current Using Scanning Tunneling Microscope with Optically Pumped GaAs
Authors: Sueoka Kazuhisa , Hayakawa Kōichi Mukasa
Published: February 2005

A scanning tunneling microscope (STM) experiment demonstrating the spin-polarized tunneling effect was performed. A GaAs thin-film sample pumped by circularly polarized light, and a ferromagnetic polycrystalline Ni tip are used. The tunneling current is perturbed by modulating the power and polarization of the pumping light. The perturbation arises due to three dominant effects: the thermal expansion of the tip or sample, the variation in excited carrier concentration in GaAs and the spin-polarized tunneling effect. The spin-polarized effect can be distinguished by observing the current dependence on the bias. Well-adjusted pumping optics allows the separate detection of the spin-polarized signal, which depends upon the circular polarization of the light and the tip magnetization. The present experiment indicates the feasibility of a spin-polarized STM with a non-magnetic tip.
Atomic Force Microscope Using an Optical Fiber Heterodyne Interferometer Free from External Disturbances
Authors: Oshio Takanori , Nakatani Noboru , Suzuki Yoshiyuki Sakai
Published: February 2005

This paper describes an atomic force microscope (AFM) using an optical fiber heterodyne interferometer free from external disturbances in the optical paths of two fibers used for measuring the small displacements of a cantilever. For the elimination of disturbances, the phases of beat signals for two points are differentiated. A special plano-convex lens with double optical axes is used for obtaining two beams at two points. The noise level of this interferometer is 4.5×10-3 nm/√Hz and is limited by the phase noise of the phase meter used. It is confirmed, by measuring the electric force between the tip and the sample, that the interferometer can be used for measuring the displacement of the cantilever. By inspecting the surface of an echellete grating, it is demonstrated that this AFM is a powerful tool for measurement of the surface on the nanometer order.
Modeling and Simulation of High Density Plasmas
Authors: Graves David B. , Hanming Wu Hanming Wu , Robert K. Porteous Robert K. Porteous
Published: February 2005

We present a model of an ECR plasma in a cylindrical (z, r) geometry with resonant zone near the substrate surface. The model combines a hybrid (particle ion-fluid electron) treatment of plasma transport with an ad-hoc model of microwave power deposition. The model is used to test the effect of the radial profile of microwave power on the spatial profiles of plasma parameters: plasma density, plasma potential and electron temperature. It is shown that for uniformity of ion flux at the substrate surface, microwave power must be peaked off axis.
Al-Cu Alloy Etching Using In-Reactor Aluminum Chloride Formation in Static Magnetron Triode Reactive Ion Etching
Authors: Masaaki Sato Masaaki Sato , Yoshinobu Arita Yoshinobu Arita
Published: February 2005

We describe a new Al-Cu alloy etching system that uses aluminum chloride formed in the reactor to build deep-submicron Al-Cu laminated interconnections. The etching residue containing copper chloride after Al-Cu etching can be removed by a flow of aluminum chloride at a relatively low temperature of 120°C. This is because copper chloride reacts with aluminum chloride to form volatile chloroaluminate copper. In the new etching system aluminum chloride is formed through the use of a second cathode covered with aluminum targets in static magnetron triode reactive ion etching (SMTRIE). With this configuration, aluminum chloride flow can be precisely controlled and highly selective deep-submicron etching of Al-Cu laminated interconnections without any residue can be achieved. It is also shown that the aluminum chloride flow suppresses after-corrosion.
A Comparison of Cl2 and HBr/Cl2-Based Polysilicon Etch Chemistries: Impact on SiO2 and Si Substrate Damage
Authors: Rembetski John F. , Chan Y D. , Boden E. , Gu Tieer , Awadelkarim O. O. , Ditizio R. A. , Fonash S. J. , Li Xiaoyu , Viswanathan C. R.
Published: February 2005

The damage produced in thin SiO2/Si structures after plasma exposure in Cl2-based or HBr/Cl2-based reactive ion etching environments is examined. The etch chemistries and parameters used were those of a poly-Si gate overetch. In this study, the damage present in the SiO2 and Si substrate after these etch exposures and that remaining after a 900°C 1 hour Ar anneal is examined for both etch chemistries. Oxide reliability is shown to be affected even by the more benign etch, even after the annealing. On the other hand, Si substrate defects are annealed out to low levels after a 700°C 1 hour anneal for both chemistries. These defects are, however, present in numbers that are large enough to affect generation lifetimes either immediately after etch or at intermediate annealing temperatures.
TiN Thin Film Prepared by Chemical Vapor Deposition Method Using Cp2Ti(N3)2
Authors: Ikeda Koichi , Masahiko Maeda Masahiko Maeda , Yoshinobu Arita Yoshinobu Arita
Published: February 2005

Two kinds of chemical vapor deposition (CVD) processes are described for depositing a titanium nitride (TiN) thin film using a biscyclopentadienyltitanium diazide (Cp2Ti(N3)2) source. One is photo-assisted CVD and the other is thermal CVD. The CVD-TiN films are evaluated using thermal desorption spectroscopy and Auger electron spectroscopy. The results reveal that the films include hydrocarbon components consisting of five carbon atoms, and nitrogen atoms desorbed at temperatures over 600°C, and then Ti-C bonds are formed in the films. The film composition (N/Ti) is affected by nitrogen partial pressure. This relationship is significant at substrate temperatures above 400°C. Light irradiation makes it possible to deposit the film at below 350°C. These results indicate that the photo-assisted CVD is effective in making high-quality TiN thin film at low temperature region.
High Rate Deposition of Silicon Dioxide Membrane by Excimer Laser Enhanced Projection Chemical Vapor Deposition from Organic Compounds at Low Temperature
Authors: Tomoura Seiichirou , Takashima Kouji , Minami Kazuyuki , Esashi Masaki , Nishizawa Jun-ichi
Published: February 2005

A novel method of high-rate deposition of silicon dioxide from organic compounds at low temperature was studied. The new method is called light projection chemical vapor deposition (CVD) utilizing an ArF excimer beam. Tetramethylorthosilicate (TMOS) and hexamethyldisilazane (HMDS) are suitable source materials. This method enables the deposition of fine SiO2 patterns without subsequent photolithography. High deposition rates of about 3500 Å/min from TMOS and about 2000 Å/min from HMDS were obtained at 2°C.
Frequency Stabilization of a Diode-Laser-Pumped CW Neodymium-Doped Yttrium Vanadate Intracavity-Doubled Solid-State Laser
Authors: Carty Timothy , Tokuyuki Honda Tokuyuki Honda , Hirokazu Matsumoto Hirokazu Matsumoto
Published: February 2005

A Brewster plate and a KTiOPO4 crystal are placed inside a laser-diode-pumped Nd:YVO4 solid-state laser cavity to cause single-frequency oscillation of the 1.06 µm cw transition. The second-harmonic frequency generated by the KTP crystal is locked to an iodine absorption line at room temperature. Difficulties with intracavity frequency doubling and the observation of intensity and frequency hysteresis during cavity length modulation are discussed.
Internal Bias Field of Sarcosine-Doped Triglycine Sulfate Crystal
Authors: Noriyuki Nakatani Noriyuki Nakatani , Naoyuki Hara Naoyuki Hara
Published: February 2005

Single crystals of ferroelectric triglycine sulfate (TGS) have been grown from aqueous solution containing 10 mol% of sarcosine. The crystal, referred to as SarTGS, shows a quite different habit from undoped TGS. The concentration of sarcosine incorporated in the crystal is, at most, 1/500 of the solution concentration. Although sarcosine is not chiral, an internal bias field E
b of 40-140 kV/m is produced. The direction and intensity of E
b, as well as the domain structure, vary according to the crystal growth sector. The directions of E
b in matching sectors in both b sides of the seed crystal are opposite to each other. In the sectors where the growing surface is parallel to the b-axis, no bias field is produced. The cause of such a feature of E
b in the SarTGS crystal is discussed in terms of symmetry considerations.
Selective Growth of Diamond Thin-Film Employing Yttria-Stabilized Zirconia Thin-Film Mask
Authors: Maki Tetsuro , Gen Liang Hou Gen Liang Hou , Takeshi Kobayashi Takeshi Kobayashi
Published: February 2005

A novel process, which employs yttria-stabilized zirconia (YSZ) as a thin film mask, has been developed to obtain selective growth of diamond films. YSZ films were prepared by pulsed ArF excimer laser deposition and rf-diode sputtering, the latter of which offered a much better masking effect than the former when the diamond film was grown by microwave plasma-assisted chemical vapor deposition with CO/H2 source gas. In scanning electron microscope images, the edge part of the selectively grown diamond film revealed a morphology somewhat different from that of the central part. Observed areal distribution of the morphology is an indication of migration of the growth species on the YSZ film mask.
Consideration of Optimal Magnet Coil Design for 1300 MWth Coal Combustion Magnetohydrodynamic Generator
Authors: Nishimura Ryo , Yoshiaki Aoki Yoshiaki Aoki , Naoyuki Kayukawa Naoyuki Kayukawa
Published: February 2005

In this paper, we discuss the effect of the cross-sectional shape of a magnet coil upon the reduction of the magnetohydrodynamic (MHD) channel length. Employing a coal-combustion plasma with semiperfect gaseous characteristics, the generator output performance of various magnet coil shapes are evaluated based on the 1-D gasdynamic model. The shape of a magnet coil cross section is optimized for a 1300 MWth supersonic Faraday-type MHD generator with a square inlet cross section. It is shown that the channel length can be shortened by 33% through optimization of the coil shape, in comparison with the case of the crescent-shaped coil producing a uniform magnetic field where the enthalpy extraction is effectively kept unchanged. Also, it is estimated that the capital cost for a stand-alone commercial MHD/steam combined plant can be decreased by more than 6% by means of this coil shape optimization.
Misorientation Dependence of Crystal Structures and Electrical Properties of Si-Doped AlAs Grown on (111)A GaAs by Molecular Beam Epitaxy
Authors: Yamamoto Teiji , Inai Makoto , Shinoda Akinori , Toshihiko Takebe Toshihiko Takebe , Toshihide Watanabe Toshihide Watanabe
Published: February 2005

Si-doped AlAs layers are grown on (111)A GaAs by molecular beam epitaxy (MBE). The crystal phase is found to change from hexagonal (H) to cubic (C) and the resistivity of AlAs layers is shown to be strongly dependent on the misorientation from exactly oriented (111)A GaAs. It is confirmed that hexagonal AlAs can only be grown on exactly oriented (111)A GaAs and that zincblende AlAs can be grown on misoriented (111)A GaAs, using X-ray diffraction and Raman scattering measurements, respectively. The lattice constants of hexagonal AlAs are determined to be a=4.034 Å and c=6.568 Å. Si-doped AlAs with a zincblende structure shows n-type conductivity and low resistivity, but Si-doped AlAs with a hexagonal structure exhibits high resistivity (>105 Ω·cm). The crystal qualities and electrical properties of Si-doped AlAs on 5°-misoriented (111)A GaAs are equivalent to those of Si-doped AlAs on (100) GaAs.
Ion-Beam-Assisted Deposition of TiN Thin Films
Authors: Kubota Hiroshi , Chen Jen Sue , Nagata Masanori , Elzbieta Kolawa Elzbieta Kolawa , Marc Aurele Nicolet Marc Aurele Nicolet
Published: February 2005

X-ray diffraction and transmission electron analyses are used to investigate changes in the microstructure that occur when TiN films are grown by sequential deposition and irradiation on unheated Si substrates. A N2-Ar gas mixture serves partly for the reactive sputter deposition of TiN from Ti in a rf magnetron target and partly for the generation of a broad ion beam in a Kaufman source. When analyzed in terms of a simple model, the data suggest the existence of a critical growth rate of two <111> bilayers of TiN per deposition-irradiation cycle. Below that rate, the columnar growth microstructure changes into a granular one with azimuthal texture.
Role of 2D Electron-Hole Lattice System in Modulated Structure of High-Tc Superconductor Bi2-xPbxSr2CaCu2O8+δ
Authors: Seiichi Kuwata Seiichi Kuwata , Wataru Kinase Wataru Kinase
Published: February 2005

The role of a 2D electron-hole lattice system in the modulated structure of Bi2-x
Pb
x
Sr2CaCu2O8+δ (Pb-doped Bi-2212) is discussed. The 2D electron-hole lattice system is constructed by neutralizing local polarization charges on the crystal surface or between two adjacent layers. Assuming that the Pb type of modulation is obtained by reversing two neighboring polarizations in the Bi type of modulation in pairs, we explain the following experimental findings: (1) the ratio of the modulation period of the Pb type structure, k
2, to that of the Bi type structure, k
1, gives discrete values, such as k
2/k
1=3/2, 5/3, and 2; (2) as x increases, k
2 tends to increase and approximately follows the relationship k
2-k
1\proptx; (3) when the sample is irradiated with an intense electron beam, the modulation of the Pb type transforms into that of the Bi type. The physical meaning of the above assumption is discussed.
Effect of Film Resistance on Characteristics of High-Tc Multilayer Junctions
Authors: Iguchi Ienari , Takeshi Kusumori Takeshi Kusumori , Hideaki Hayashida Hideaki Hayashida
Published: February 2005

The effect of film resistance on high-T
c tunnel and proximity-effect multilayer junction characteristics is investigated in detail. The calculation based on the four-probe method is presented. It is shown that the measured tunnel resistance greatly deviates from the actual tunnel resistance when the film resistance is comparable to or larger than the latter. The semiconductive behavior with temperature above T
c, which is frequently observed in the measured tunnel resistance of high-T
c tunnel junctions, is attributed to the effect of film resistance, while the calculated actual tunnel resistance is found to be almost temperature-independent. The puzzling temperature dependence of junction resistance in SNS multilayers (S: HTSC, N: normal conductor), which exhibit a quasi-long-range proximity effect, is also explained by this calculation.
Successful Pattern Matching with a Large Number of Reference Patterns Using a Joint Fourier-Transform Correlator
Authors: Qiong Zhan Qiong Zhan , Takumi Minemoto Takumi Minemoto
Published: February 2005

Two kinds of modification of the joint transform correlator to perform pattern matching are proposed and the mechanisms are analyzed. Simulation and experimental results show that pattern matching is executed correctly by the modified JTCs; it is shown that one of the two modified joint transform correlators is equivalent to matched filtering and the other corresponds to pure-phase-only filtering.
Nonresonant Third-Order Susceptibility Measurements in 4'-(Pentyloxy)-4-Biphenyl Carbonitrile (5OCB)
Authors: John Philip John Philip
Published: February 2005

This paper reports, for the first time, the determination of the real part of the third-order nonlinear susceptibility χ(3) (-ω; ω, 0, 0) in the isotropic phase of a nematic liquid crystal 4'-(pentyloxy)-4-biphenyl carbonitrile (5OCB), based on electrooptic Kerr effect experiments. The highest value of χ(3) observed near the nematic to isotropic transition temperature at 632.8 nm is found to be 8.02×10-19 m2 v-2. The observed value of χ(3) in this medium is about 113 times higher than that of CS2.
Study of YBa2Cu3O7 Superconductor by Low-Temperature Scanning Tunneling Microscopy and Spectroscopy
Authors: Tanaka Masamoto , Takebayashi Seiki , Hashimoto Misao , Kashiwaya Satoshi , Hirayama Fuminori , Koyanagi Masao
Published: February 2005

The electronic structure of YBa2Cu3O7 (YBCO) superconductor was studied by low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS), since the electronic states of CuO2 planes in the superconducting state may shed light on the mechanism of high-T
c superconductivity. Experiments were performed on the cleaved surface of a bulk single-grain YBCO specimen at 4.2 K. Two different STS conductance spectra were obtained, a BCS-like one and a metalliclike one. These spectra were observed alternately with a periodicity of 0.8±0.2 nm, suggesting that YBCO has a two-dimensional structure in which CuO2 planes are strongly superconducting and CuO chains are metallic-like.
Delay Properties of Optical Wave in Semiconductor Trench for Depth Measurement Using Interference Spectroscopy
Authors: Shirasaki Hirokimi , Kondo Noriyuki , Abematsu Atsushi
Published: February 2005

In the depth measurement of trenches on a semiconductor substrate by means of interference spectroscopy, we sometimes cannot measure the depth when the diameter approaches the wavelength of visible light. To investigate the cause, we determined the delay properties from the reflected intensity data obtained by interference spectroscopy. Then, we confirmed that the delay time in the short wavelength is nearly equal to the time taken by the light to reach the bottom and return to the entrance. However, we found that when the trench diameter approaches the wavelength used in measurement, the change of delay becomes long.
Ba(Ti, Zr)O3 Ceramics Sintered with Lead Borate Glass
Authors: Chunz-Heuy Wang Chunz-Heuy Wang , Long Wu Long Wu
Published: February 2005

The sintering of Ba(Ti, Zr)O3 ceramics is significantly influenced by the addition of 4PbO·B2O3. The eutectic temperature of 4PbO·B2O3 is around 500°C, so it exists as a liquid phase during the sintering process. Grain growth in Ba(Ti
y
Zr1-y
)O3 exhibits a peculiar phenomenon. The liquid has high surface tension which aids solubility and penetration. As a consequence, the spreading liquid can penetrate solid-solid interfaces. Penetration leads to disintegration of the solid and subsequent rearrangement of fragments. The theory of grain growth in the presence of a liquid phase is examined in terms of the equation R

n
=k
*
t. The grain growth kinetic exponent, n, has an inverse relationship with the rate of grain growth. With suitable amounts of glass frit and sintering temperature, the density of the ceramics was enhanced and the dielectric and piezoelectric properties were improved.
Field-Induced Biaxiality in SmA Phase of a Liquid Crystal Exhibiting Electroclinic Effect
Authors: Kimura Munehiro , Kobayashi Tadashi Akahane
Published: February 2005

The field-induced biaxiality of a liquid crystal which exhibits a strong electroclinic effect in the SmA phase has been detected by means of transitional dielectric constant measurement. The biaxiality in dielectric constants increases along with the molecular tilt as the applied voltage increases and as the temperature approaches the SmA-SmC* transition point. These experimental findings areexplained qualitatively in terms of a Landau-type free energy theory by adding a term which represents the effect of the induced dielectric biaxiality.
Structures of Carbon Deposits Formed on a Graphite Electrode during Fullerene Generation
Authors: Ata Masafumi , Matsuzawa Nobuyuki , Kijima Yasunori , Imoto Jun'etsu Seto
Published: February 2005

Silver-colored carbon adducts were grown on a graphite electrode connected to the negative lead during fullerene preparation by an electric arc method, and hemispherical carbon adducts were observed with scanning electron microscopy. The carbon adducts were also observed with transmission electron microscopy, which showed spherical carbon particles of 50-300 Å in diameter having a graphitic layered structure. X-ray diffraction measurements suggest that the graphitic stacking of the spherical carbon particles has a turbostatic layered structure. The mechanism of the formation of these carbon adducts as well as fullerenes and nanotubes is discussed on the basis of these observations and by estimation of spin concentrations of each product.
Nonlinear Optical Properties of Si(111)7×7: Intensity Behavior of Second Harmonics from the Polarizations along [21̄1̄] and [011̄] Axes
Authors: Nakamura Ken , Yamamoto Hiroyoshi , Domen Kazunari , Hirose Hazime Shimizu
Published: February 2005

Intensity distribution of s- and p-polarized second harmonics (SH) generated on Si(111)7×7 was observed at the incidence angle of 20°. Observed s- and p-polarized SH were generated from polarizations induced along [21̄1̄] and [011̄] axes, respectively. SH generated from the polarization along [011̄] axis showed an intensity behavior different from the fourfold symmetry which is expected from the surface structure.
Electron Energy Distribution Detection in Symmetrically Driven RF Argon Discharge
Authors: Takashi Kimura Takashi Kimura , Kazuyuki Ohe Kazuyuki Ohe
Published: February 2005

The electron energy distribution function (EEDF) is measured with a Langmuir probe in a symmetrically driven capacitively coupled rf argon discharge. The distortion of the probe current-voltage characteristics by rf plasma potential fluctuation, which is suppressed by electric circuit resonance among an inductance, the electrode-plasma sheath and the plasma-ground stray capacitances, is finally eliminated by applying the remaining fluctuation to the probe. The detected EEDF differs from the theoretical one obtained from the Boltzmann equation.
Recovery Effect from a Deposit on the Anode Wire of Proportional Counters
Authors: Yamauchi Makoto , Kawai Nobuyuki , Atsumasa Yoshida Atsumasa Yoshida , Masaru Matsuoka Masaru Matsuoka
Published: February 2005

We have found a recovery effect from a deposit on the anode wire of proportional counters after high count detection. Usually we use a quenching gas of some organic material for proportional counters. During the development of position-sensitive proportional counters, we found that isobutylene as a quenching gas creates a deposit on the carbon anode wire in proportional counters under high irradiation, while carbon dioxide eliminates the deposit. Furthermore, we have measured the expansion of the deposit on the anode wire using an X-ray beam of 0.15 mmφ.
Relative Sensitivity Factors for Submicron Secondary Ion Mass Spectrometry with Gallium Primary Ion Beam
Authors: Satoh Hitomi , Masanori Owari Masanori Owari , Yoshimasa Nihei Yoshimasa Nihei
Published: February 2005

Relative sensitivity factors (RSFs) of thirteen elements in the oxide glass matrix in secondary ion mass spectrometry (SIMS) excited by a gallium focused ion beam were determined. RSFs were obtained by analyzing powder particles of standard glass samples. Whole volumes of each particles were analyzed in the “shave-off” mode in order to avoid topographic effects. Reproducibility of RSFs was good, and sample-to-sample scattering of values was relatively small. Dependence of RSFs on the first ionization potential was shown to be reasonable. In order to check the validity of the RSFs, coal fly ash particles were analyzed. The results were in reasonable agreement with the data obtained through the bulk chemical analysis.
Ultrasonic Correlation Analysis in Quefrency Domain for Structural Imaging
Authors: Matsushige Hirotaka Okabe
Published: February 2005

An ultrasonic quefrency (Fourier transformation of frequency) analysis was utilized to image the internal structure of materials. The imaging method comprises four processes: (1) calculation of spectrum, (2) division by the power spectrum of a pulse or other component, (3) Fourier transformation into the quefrency domain, and (4) analysis and imaging in the quefrency domain. In this study, we applied this method to image the defects in carbon-fiber-reinforced plastics (CFRP). Compared with the conventional ultrasonic images, this method was proven to provide greatly improved images, suggesting that this method is a powerful tool for nondestructive inspection of composite materials including CFRP.
Analysis of Metallic Multilayers Using Hypersonic Surface Waves Induced by Transient Reflecting Gratings
Authors: Shen Qing , Akira Harata Akira Harata , Tsuguo Sawada Tsuguo Sawada
Published: February 2005

Gigahertz surface acoustic waves (the Rayleigh-like modes) have been optically generated and detected on ultrathin (<1 µm) metallic single-layer and multilayered films attached to glass substrates using the laser-induced transient reflecting grating (TRG) technique. The dispersion relations of the excited Rayleigh-like modes could be constructed experimentally and theoretically. By finding the best fitting of the theoretical dispersion curves to the experimental data, this method can be used to deduce the elastic constants of ultrathin multilayered films.
Laser-Stimulated Scattering Microscope Study of an Ion-Implanted Silicon Surface
Authors: Harata Akira , Shen Qing , Takayuki Tanaka Takayuki Tanaka , Tsuguo Sawada Tsuguo Sawada
Published: February 2005

Surface modification of a silicon single crystal induced by argon ion implantation of a light dose condition (300 keV, 1011 atoms/cm2) has been investigated using a laser-stimulated scattering microscope, whose operational principle is based on microscopic measurements of transient reflecting gratings (TRGs). One-dimensional distributions of various material parameters, velocity, onset time and attenuation coefficient of surface acoustic waves and parameters relating to thermal diffusion, thermal expansion and optical absorption, are determined by analyzing the TRG responses measured sequentially along a line across the implanted and unimplanted regions. Some theoretical aspects are presented for the empirical equation used in deducing these parameters from the TRG responses. The change in the anisotropic property of the acoustic velocity is also discussed.