bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Evaluation of Aluminum Volume Fraction Using Photoacoustic Method in Aluminum-Epoxy Composites Prepared by Sedimentation
Authors: Ho Chul Kim Ho Chul Kim , Moon Gyu Jang Moon Gyu Jang
Published: October 2002

The photoacoustic signal decreased along the sedimentation direction of aluminum-epoxy composites due to the increase in effective thermal conductivity as aluminum volume fraction increases. Quantitative estimation of the aluminum volume fraction was made from the variation of the photoacoustic signals incorporating the Rosenc-waig-Gersho theory with the Maxwell–Garnet effective medium theory. The result was in excellent agreement with the result of quantitative image analysis to within 5%, which justifies the use of the photoacoustic method in determining the filler volume fraction in two-phase composites.
Frequency Detuning and Stabilization of a Diode Laser Using the Zeeman Shift of the Saturated Absorption Signal of Rubidium Atoms
Authors: Ho Seong Lee Ho Seong Lee , Sung Hoon Yang Sung Hoon Yang , Young Bum Kim Young Bum Kim , Sang Eon Park Sang Eon Park , Hyuck Cho Hyuck Cho , Jong Dae Park Jong Dae Park
Published: October 2002

We observed saturated absorption spectra of the 87Rb atom under a magnetic field of several millitesla with a diode laser oscillating at 780 nm. The spectra were compared with the theoretical ones obtained on the basis of Nakayama's four-level model. We numerically computed Zeeman splittings of the 52
P
3/2 excited state of the atom. As the magnetic field increased to 5 mT, the absorption peak of the F=2→F'=3 transition shifted almost linearly up to about 62 MHz. The shift direction was reversed by changing the polarization combination of the pump and probe lasers. The measured frequency stability, when the laser was locked at the absorption peak, was better than σy(τ)= 1 ×10-11τ-1/2 for the sampling time of 0.01 s≤τ≤10 s.
Synthesis of AlN Thin Films on Sapphire Substrates by Chemical Vapor Deposition of AlCl3–NH3 System and Surface Acoustic Wave Properties
Authors: Kaya Kiyoshi , Kanno Yasuhito , Takahashi Hiroshi , Hirai Yoshihiko Shibata
Published: October 2002

Thin films of AlN were prepared on (012) sapphire substrates by chemical vapor deposition using AlCl3, NH3, H2 and N2 gases. Crystal orientations, surface microstructures, oxygen impurity contents of the films and surface acoustic wave (SAW) properties determined using an interdigital transducer were investigated. Under optimized conditions, epitaxial AlN films were deposited and crystal orientation of AlN films increased as the thickness of the films increased. Oxygen impurity contents were less than 1 atm%. The dependence of SAW velocity along the [001] AlN axis on the film thickness was in good agreement with the theoretical prediction and the temperature coefficients of the center frequency increased as the film thickness increased. These tendencies are considered to be explained by the high crystal orientation and low oxygen impurity content of AlN epitaxial films.
Optical Energy Gap Measurement of Semiconductor Ultrathin Films Using Optical Waveguides
Authors: Naganori Takezawa Naganori Takezawa , Isamu Kato Isamu Kato
Published: October 2002

Measurement of the optical energy gap (E
o) using a slab optical waveguide (SOW) has been studied. With increasing hydrogenated amorphous silicon ( a-Si:H) film thickness, transmittance was found to decrease with periodic oscillation. It has been clarified that the oscillation is caused by the change of the field strength distribution of a guided mode in a-Si:H according to the increase of a-Si:H film thickness, using the four-layer structure SOW simulation. By removing the oscillation due to the dependence of transmittance on a-Si:H film thickness, the influence of the oscillation on the values of E
o can be eliminated. As a result, it has been demonstrated that E
o of a-Si:H with thickness on the order of 1/40 that of samples used in the conventional method can be measured. It has been clarified that sufficient absorption to determine E
o of a-Si:H ultrathin films is obtained because the sensitivity of the sensor is increased by changing the size of the SOW.
A Silicon Oxide Antireflective Layer For Optical Lithography Using Electron Cyclotron Resonance Plasma Deposition
Authors: Mimura Yoshiaki , Kiuchi Mikiho , Anzai Kazunori , Katsuyuki Machida Katsuyuki Machida
Published: October 2002

Using electron cyclotron resonance plasma deposition, we have developed an SiO

x

film as an antireflective layer (ARL) for the gate process of LSI fabrication by i-line and KrF lithography. The ARL is an absorption type and is 100 nm thick. The estimated optimum optical properties of the ARL for i-line were n=2.3–2.6 and k=0.5–0.6. For KrF, they were n=1.8–2.1 and k=0.5–0.6. An SiO

x

film having these properties can be reproducibly deposited at SiH4/O2 gas flow rate ratio of 1.3 for i-line and 1.1 for KrF. The chemical compositions of the films are SiO0.5 for i-line and SiO1.0 for KrF. The SiO0.5 film was used as an i-line ARL for 0.35-µ m LSI gate fabrication and superior process performance and sufficient critical dimension controllability (variation within 19 nm of 3σ) were obtained.
Microscopic Brillouin Scattering Study in TeO2: Pressure Dependence of Acoustic Modes
Authors: Muhtar Ahart Muhtar Ahart , Takehiko Yagi Takehiko Yagi , Yasunari Takagi Yasunari Takagi
Published: October 2002

The pressure-induced ferroelastic transition of TeO2is investigated in detail using microscopic Brillouin scattering in the backward geometry as a function of pressure. Both the quasi-transverse mode (T') and the quasi-longitudinal mode (L') are measured from 1 atm. to 2 GPa (transition pressurePc=0.9 GPa), using a diamond anvil cell for various propagation directions of phonons, of which the deviations ψ from [110] are 2.3°, 4°, 7.6°, 25°, 35°, and 45°. TheT'-mode frequency for 2.3° decreases to the lowest value of ∼1.37 GHz atPc. Experimental results are generally explained on the basis of the Landau theory of the ferroelastic transition under pressure. It is concluded that the phase transition of the TeO2crystal is driven by a soft acoustic mode. However, for the mode at ψ=45° corresponding to the pure longitudinal modeC11, an elastic anomaly found in the neighborhood ofPcis larger than that for other modes.
Brillouin Scattering Study on KNO 3 Crystal: Appearance of Intermediate Phase on Heating
Authors: Akihiro Nagase Akihiro Nagase , Yoshio Takeuchi Yoshio Takeuchi , Yasunari Takagi Yasunari Takagi
Published: October 2002

The structural phase transition of potassium nitrate, KNO3, has been investigated by means of Brillouin scattering. With increasing temperature, a previously unreported change in other experiments was observed in Brillouin shift, linewidth and mode number, which varied for many measurements. It appears that a phase other than the α- and β-phases, called the “intermediate phase”, appeared between these two phases. This phase always started to appear at 128°C, but did not disappear at a fixed temperature for any measurement. This behavior is similar to that of the γ-phase. We have discussed the origin and nature of the intermediate phase.
Observation of Surface Defects using Photoacoustic Microscope and Quantitative Evaluation of the Defect Depth
Authors: Hoshimiya Tsutomu , Endoh Haruo , Hiwatashi Yoichiro
Published: October 2002

Quantitative trial of nondestructive evaluation (NDE) of a variable-depth defect using photoacoustic (PA) microscopy has been demonstrated. Two kinds of slit-type simulated defects, cross sections of which are rectangular and arc-shaped, were fabricated on a metal specimen by electrical discharge processing. Imaging of defects by PA microscopy enabled precise determination of both the location of edges and the shapes of defects. PA imaging of an artificially made vertical defect with linearly increasing depth showed that the best result agrees well with a model based on a line heat source along a metal wall in a defect.
Photodissociation of Iodobenzene and Photoacoustic Detection of the Products Using a Dual-Purpose Q-switched YAG Laser
Authors: Hidekazu Takekoshi Hidekazu Takekoshi , Shigeo Hayashi Shigeo Hayashi
Published: October 2002

The third harmonic of a Q-switched Nd:YAG laser is used to decompose iodobenzene C6H5I dissolved in benzene. Photoacoustic (PA) signals are observed simultaneously. They initially have a finite value arising not only from the solvent but also from the reaction of the radicals, C6H5· and I·, since the quantum yield of the photodissociation is reported to be approximately 100%. The PA intensity increases with the number of laser shots since the the reaction product, iodine, forms a charge-transfer complex with the solvent, which also absorbs the laser light. From the ratio of initial PA signal to that due to the complex, the quantum yield of chemically induced PA is deduced to be less than 60%.
Brillouin Scattering Study of Glass-Forming Propylene Glycol
Authors: Yoshihara Akira , Kojima Hiromitsu Sato
Published: October 2002

Brillouin scattering of hypersonic sound waves by fragile glass-forming propylene glycol has been studied using a (3+3)-pass vernier tandem Fabry-Pérot interferometer at temperatures between 364 K and 140 K. The velocity dispersion has been analyzed using the Cole-Davidson model (βCD=0.45). The relaxation time was found to obey the Arrhenius law, and we have obtained ΔE=0.28 eV and τ0=1.26×10-15s. The relaxation strength (or the Debye-Waller factor in the mode coupling theory (MCT)) was found to obey the (Tc-T)1/2law belowTc=314 K, as predicted by the MCT. However the crossover temperatureTcwas much higher than our previous result ofTc=227±5 K which was obtained from the broadband susceptibility spectra.
Ultrasonic Study of Gelation Process in Egg White Proteins
Authors: Jong-Rim Bae Jong-Rim Bae
Published: October 2002

Ultrasonic velocity and absorption measurements were made in ovalbumin, conalbumin and ovomucoid which are protein constituents of egg white, at 3 MHz over the temperature range of 10 to 95° C using the pulse-echo-overlap method. The gelation process induced by heat was studied based on the changes in velocity and absorption. The gelation temperatures of ovalbumin and conalbumin were 70° C and 50° C, respectively. However the gelation of ovomucoid did not occur under the range of temperatures investigated. The changes in velocity and absorption due to gelation were observed as a function of time at aging temperatures ranging from 50 to 95° C for conalbumin, and from 70 to 95° C for ovalbumin. The experimental results showed that the changes were prominent at 55° C in conalbumin and at 75° C in ovalbumin. Hysteresis phenomena were also observed by varying the aging temperature. The phenomena are associated with the memorizing effect of the network structure of protein in gel. It was demonstrated that the ultrasonic technique was useful for monitoring the gelation process.
Longitudinal Structural Relaxation of Highly Viscous Liquid: Tetraethylene Glycol
Authors: Noudou Takaaki , Matsuoka Tatsuro , Shinobu Koda Shinobu Koda , Hiroyasu Nomura Hiroyasu Nomura
Published: October 2002

The sound velocities of tetraethylene glycol over the frequency range from 100 MHz to 10 GHz and in the temperature range from 243 to 313 K were measured by Brillouin scattering and high-resolution Bragg reflection methods. Velocity dispersion, which is attributed to structural relaxation, was observed for the frequencies investigated here. The relaxation curves represented by the longitudinal reduced storage modulus were well explained by a double relaxation. The relaxation strength of the fast process decreased with decreasing temperature. The fast process disappeared around 260 K. The relaxation times of the fast process obeyed the Arrhenius law, while the temperature dependence of the relaxation times of the slow process showed non-Arrhenius behavior.
Measurements of Absorption Coefficients in the Deep-Sea Area
Authors: Umezawa Masaaki , Tsuchiya Toshio , Kikuchi Toshiaki , Hashimoto Akio Hasegawa
Published: October 2002

In order to design deep-sea acoustic devices, it is very important to estimate the sound absorption loss in the deep sea. It is known that there is a discrepancy between the measured absorption loss in a water tank and that in the deep sea. We have measured the sound absorption losses in the deep sea using the deep submergence vehicle “SHINKAI 6500” of the Japan Marine Science and Technology Center (JAMSTEC). Our data are close to those measured in the laboratory by Fisher. [rf:1] It appears that absorption loss decreases quadratically as a function of depth.
1.9-GHz-Band Surface Acoustic Wave Device Using Second Leaky Mode on LiTaO3
Authors: Yasumi Kobayashi Yasumi Kobayashi , Naoki Tanaka Naoki Tanaka , Kuniyuki Matsui Kuniyuki Matsui , Hiroshi Okano Hiroshi Okano , Tatsuro Usuki Tatsuro Usuki , Kenichi Shibata Kenichi Shibata
Published: October 2002

The propagation characteristics of a new high-phase-velocity leaky surface acoustic wave (SAW) mode, which is called the second leaky mode, in a periodic structure on LiTaO3 (90°, 90°, 31°) aere analyzed experimentally. The propagation loss is the lowest when the K
H (K=wave number, H=Al electrode thickness) parameter is about 0.5. The higher mode of the second leaky mode is excited when the K
H parameter is larger than 0.7. A ladder type band-pass SAW filter utilizing the second leaky mode on LiTaO3 was designed and fabricated by applying the analysis results to the periodical structure. The pitch of the electrode fingers is 0.8 µ m. The center frequency of the pass band is 1.938 GHz. The minimum insertion loss is 3.3 dB. The attenuation at the center frequency ±100 MHz is 25 dB. The measured characteristics of this filter can be sufficient for practical mobile communication systems.
Analysis of Surface Acoustic Waves Obliquely Propagating under Metallic Gratings with Finite Thickness
Authors: Ken-ya Hashimoto Ken-ya Hashimoto , Goh Endoh Goh Endoh , Makoto Ohmaru Makoto Ohmaru , Masatsune Yamaguchi Masatsune Yamaguchi
Published: October 2002

In this paper we propose a method of analysing surface acoustic waves (SAWs) propagating obliquely under a metallic grating with finite thickness. The discrete Green function originally developed for SAWs longitudinally propagating under the metallic grating is modified, and applied to the characterisation of obliquely propagating SAWs. The method is applied to the analysis of Rayleigh SAWs obliquely propagating on 128° Y
X-LiNbO3 (128-LN), and the result is shown to be in good agreement with experiments. Leaky SAWs obliquely propagating on 36° Y
X-LiTaO3 (36-LT) are also analysed and compared with the result obtained for 128-LN.
Evaluation of Surface Defects Using Surface Acoustic Waves Generated by Phase Velocity Scanning of Laser Interference Fringes
Authors: Harumichi Sato Harumichi Sato , Hideo Cho Hideo Cho , Hideo Nishino Hideo Nishino , Hisato Ogiso Hisato Ogiso , Kazushi Yamanaka Kazushi Yamanaka
Published: October 2002

In order to maintain the reliability of structural materials such as ceramics, it is important to nondestructively detect surface defects that reduce the strength of materials. Therefore, we have developed the phase velocity scanning (PVS) method. The PVS method does not involve the use of coupler (noncontact) and has excellent directivity. We report that the sensitivity for detecting surface acoustic waves (SAW) was improved using a video signal. The video signal S/N ratio, which is defined as the ratio of generated SAW to background noise, is 46.5 dB. Back propagation waves were not detected within the limit of the S/N ratio. Utilizing this excellent directivity we succeeded in B-mode imaging to detect indentation cracks (Knoop indentation cracks). Scattered waves were detected on the indentations of above 100 gf but could not be detected for those of below 50 gf. This result implies that this method can be used to evaluate the critical load of initiating median cracks which is difficult using conventional methods.
Analysis of Acoustic Field in Liquid Radiated by Dispersive Surface Acoustic Wave Transducer
Authors: Nobuhiro Tasaki Nobuhiro Tasaki , Koichi Mizutani Koichi Mizutani , Keinosuke Nagai Keinosuke Nagai
Published: October 2002

We obtained images of the acoustic field radiated from a dispersive surface acoustic wave (SAW) device by numerical calculation and by experiment in order to control the field by varying the frequency. First, a numerical calculation using Smith's equivalent circuit taking loss into account was carried out. Then we produced a transducer using a dispersive SAW device driven in liquid. We made an experiment using the transducer and visualized the radiated acoustic field by the Schlieren method to confirm the validity of the calculation method. The transducer can be used to scan radiating positions over a distance of 9 mm for driving frequencies in the range of 1.5–2.5 MHz. The numerical results agree well with the experimental ones.
Acoustic and Vibrating Properties of C/C Composite
Authors: Pan Haitao , Yasuda Sadayuki Ueha
Published: October 2002

An orthogonal anisotropic material is proposed for use as a new vibrating material of an ultrasonic longitudinal vibrator, with large diameter as well as uniform vibration on the radiating surface. As the orthogonal anisotropic material, C/C composite is used in an experiment due to its high strength in two orthogonal directions. The acoustic properties of C/C composite are measured using acoustic waves and compared to those obtained from the elastic constants. A longitudinal vibrator made of C/C composite is designed and constructed based on these properties. The vibration parameters including the resonance frequency and mechanical quality factor are measured and discussed. The vibration velocity on the radiating surface of a vibrator the diameter of which is larger than half the wavelength of the longitudinal wave, is obtained experimentally and numerically to reveal the feasibility of acquiring a uniform velocity distribution using C/C composite.
Ultrasonic Joining of Polytetrafluoroethylene Sheets Using a Lateral Face of Rod Vibrating Longitudinally at 19 kHz
Authors: Yuji Watanabe Yuji Watanabe , Eiji Mori Eiji Mori
Published: October 2002

Ultrasonic joining of polytetrafluoroethylene (PTFE; Teflon
T
M
) sheets using a lateral face of a rod vibrating longitudinally at 19 kHz is studied. We joined two PTFE sheets 0.3–0.8 mm thick using a 19 kHz longitudinal-mode joining system having a 10 mm×80 mm joining area. The joining tool was a straight bar vibrating longitudinally at 19 kHz. The lateral face of the bar could rub the PTFE face strongly. The temperature rise caused by the rubbing was high enough to enable joining. Joining was accomplished in 3–5 s. The maximum joint strength of sheets 0.5 mm thick was 2.4 MPa under the condition that static pressure was 6 MPa and joining time was 10 s.
Analysis of the Transformation of Mechanical Impact Energy to Electric Energy Using Piezoelectric Vibrator
Authors: Umeda Mikio , Nakamura Kentaro , Ueha Sadayuki
Published: October 2002

We propose a new mechanism of electric power generation in which mechanical impact energy is transformed to electric energy by a piezoelectric transducer. To clarify the relationship between the input mechanical impact energy and the output electric energy in this method, we measured the electric output of a piezoelectric vibrator stimulated by an impact with a steel ball. An electrical equivalent model of the phenomenon is proposed to analyze the transformation efficiency as functions of the electromechanical coupling coefficient, the mechanical loss and the dielectric loss of the vibrator.
Effects of Channel Mobility on SiC Power Metal-Oxide-Semiconductor Field Effect Transistor Performance
Authors: Kobayashi Sota , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

The performance of 6H- and 4H-SiC power metal-oxide-semiconductor field effect transistors (MOSFETs) has been theoretically studied, taking account of channel resistances and mobility anisotropy. For low-voltage (<500 V) devices, the total on-resistance is severely limited by the channel resistance, due to the very low drift-region resistance and to the relatively low channel mobility in SiC. Even in high-voltage (>500 V) devices, a channel mobility higher than 50 cm2/Vs is required to ensure that SiC power MOSFETs are practical.
Surface Morphology Control of YBa2Cu3Ox Thin Films Grown by Metalorganic Chemical Vapor Deposition Using Vicinal SrTiO3 Substrates
Authors: Hideaki Zama Hideaki Zama
Published: October 2002

We have used vicinal SrTiO3 substrates for improving and controlling the surface roughness of a YBa2Cu3O

x

film. If we use a SrTiO3(100) substrate, the surface morphology of the film is abruptly degraded over a thickness equivalent to 15 unit cells. In contrast to using a SrTiO3(100) substrate, good surface morphology is maintained, even at 20-unit-cell thickness, when using a vicinal SrTiO3(100) substrate misoriented by 2°. The reason is that the effective terrace width produced by 2° misorientation is almost equal to the migration length of species on the growing surface. This is suitable for controlling the surface morphology of a YBa2Cu3O

x

film.
Relationship between Variable Capacitance Characteristic and Effect of Ferrite Magnetic Wedge in Capacitor Motor Switched by Triac
Authors: Kaga Akio , Tajima Katsubumi , Masaru Satoh Masaru Satoh , Tadahito Itoh Tadahito Itoh
Published: October 2002

In this study, the capacitance of capacitors connected in series with the auxiliary winding of a capacitor motor was changed by switching the firing angle of the triac, and ferrite magnetic wedges were inserted into the stator slots to reduce the flux density distortion in the air gap.
Sputtering Phenomenon Induced by Laser-Ablated Particles
Authors: Miyashita Takasumi Ohyanagi , Kouichi Murakami Kouichi Murakami , Osamu Yoda Osamu Yoda
Published: October 2002

We have investigated the dynamic behavior of laser-ablated Si particles by means of time-resolved X-ray absorption spectroscopy. Laser-ablated Si particles are found to induce sputtering of an Al plate which is located near the Si target. Moreover, it is suggested that Si cluster formation is enhanced by collisions between laser-ablated Si particles and Si particles backscattered by a Si wafer located near the Si target. We tentatively assign unidentified X-ray absorption peaks appearing near 120 eV to small Si clusters.
Calculation of the Surface Potential across Langmuir-Blodgett Films with Polar Molecules
Authors: Mitsumasa Iwamoto Mitsumasa Iwamoto , Eiji Itoh Eiji Itoh
Published: October 2002

The surface potentials across multilayer films with polar molecules were calculated assuming that the constituent molecules are rod-like and orientationally distributed. In the calculation, the internal electric field was taken into consideration. The effect of the excess charges displaced from the base metal electrodes was also taken into consideration. It was found that the excess charges displaced from base metal electrodes contribute to the change in orientation of polar molecules which results in a change in the voltage across the monolayers. The experimental results for precursor films of polyimide with polar groups (–OCF3, –OCH3) are discussed based on the analysis developed here.
Ferromagnetic Mn-Based Decagonal Alloys at Room Temperature
Authors: Yoshihiko Yokoyama Yoshihiko Yokoyama , Akihisa Inoue Akihisa Inoue
Published: October 2002

A decagonal (D) phase was observed in rapidly solidified Mn-based Mn–Al–Ge–B alloys. The composition range for formation of the D-phase is 22 to 28% Al, 12 to 24% Ge and 7 to 17% B for Mn45Al55-
x
-
y

Ge

x

B

y

alloys. The D-phase has fine grains 50 to 200 nm in diameter and the periodic lattice spacing along the c axis determined from the electron diffraction pattern is 1.2 nm. The D-phase changes to a crystalline phase after annealing for 60 s at 950 K. The D-alloys exhibit ferromagnetism at room temperature and the saturation magnetization under a field of 18 kOe (J
18), remanence (B
r) and intrinsic coercive force ( i
H
c) are 21 emu/g, 8 emu/g and 300 Oe, respectively, for Mn45Al25Ge15B15. The ferromagnetic D-alloys have a Curie temperature of 590 K in the as-quenched state and the annealing for 60 s at 950 K causes a decrease in T
c of about 40 K. The occurrence of a ferromagnetic D-phase in Mn-based alloys is important in the future development of ferromagnetic quasicrystalline alloys with high coercive forces which result from the D-structure with strong anisotropy.
High-Pressure X-ray Diffraction Study of CuFeO2
Authors: Zhao Tong-Rong , Hasegawa Masashi , Takei Humihiko , Tadashi Kondo Tadashi Kondo , Takehiko Yagi Takehiko Yagi
Published: October 2002

A high-pressure X-ray diffraction experiment on hydrostatic compression of CuFeO2 up to about 10 GPa was performed at room temperature using a diamond anvil cell. An anisotropic compression of the unit cell was observed: The ratio c/a in the hexagonal cell increases considerably with increasing pressure. No phase transformation was observed and the delafossite structure is stable up to 10 GPa.
In Situ Observation of Etching Processes of Silica Glasses by Silicon Melts
Authors: Ikari Atsushi , Matsuo Syuitsu , Kazutaka Terashima Kazutaka Terashima , Shigeyuki Kimura Shigeyuki Kimura
Published: October 2002

In order to investigate etching of silica crucibles by silicon melts during silicon crystal growth, an in situ observation was made on formation of white dots with brown edges, called “brownish rings”, at the silica-silicon melt interface. The formation of brownish rings was found to be influenced by melt temperature, OH concentration in silica glasses and oxygen concentration in silicon melts. The growth of brownish rings shows a linear dependence on dipping time and the growth mechanism is essentially the same as that for the devitrification of silica glasses. These results suggest that in order to control the etching of silica crucibles during silicon crystal growth, it is important to control both properties of silica glass and oxygen concentration in silicon melts.
Interface Reactions between Manganese Zinc Ferrite Single Crystals and SiO2–PbO–ZnO–MnO Systems
Authors: Kim Hae June Je , Byeon Soon Cheon , Hong Kug Sun , Son Yong Bai , Jang Sung Do , Chong Hee Kim Chong Hee Kim
Published: October 2002

The interface reactions between Mn–Zn ferrite single crystals and SiO2–PbO–ZnO–MnO systems were investigated using a scanning electron microscope, an electron probe microanalyzer, and an X-ray diffractometer. No intermediate phase was formed at the interface after reaction at 1000° C, but the concentration profiles of Zn and Mn ion at the ferrite adjacent to the interface were markedly affected by their atomic ratio in the glass. When 6 mol% MnO and 4 mol% ZnO, the ratio of which was similar to that in the ferrite, were added to the SiO2–PbO binary system, the concentration of Zn ion was increased at the ferrite adjacent to the interface. It was confirmed that the diffusion rate of Mn ion in the glass melt was higher than that of Zn ion. Therefore, the enrichment of Zn ions was considered to be caused by the higher dissolution rate of Mn ion into the glass from the ferrite than that of Zn ion. It was found that when 7 mol% MnO and 3 mol% ZnO, the ratio of which was higher than that in the ferrite, were contained in the glass, the concentrations of Zn and Mn ions hardly changed at the ferrite adjacent to the interface.
Electrostatic Surface Wave Resonances for an Inhomogeneous Plasma Cylinder
Authors: Gabriele Cicconi Gabriele Cicconi
Published: October 2002

Two solutions of the Laplace differential equation for an inhomogeneous cold plasma cylinder, whose radial electron density profile is considered parabolic and parametrically variable, are presented and discussed. In the first case (a smooth profile) the equation obtained is the confluent hypergeometric differential equation, also called the Kummer equation or the Pochhammer-Baines equation. The solution is expressed in terms of Kummer (or confluent hypergeometric) functions. In the second case, which is a more general case, the series solution to the same equation is achieved by the method of Frobenius. The surface resonance conditions are investigated and the profile-dependent frequency spectrum calculated when an harmonic electric field is incident perpendicularly to the cylinder axis of the plasma considered as collisionless and opaque. In particular, the effects of boundary different media in which the plasma cylinder is embedded are estimated.
Two-Dimensional Plasma Mapping Using String Probes
Authors: Akira Tsushima Akira Tsushima , Keiji Hasegawa Keiji Hasegawa
Published: October 2002

A method for mapping a two-dimensional plasma density distribution was developed by combining probe measurements with computed tomography. This method reduces data for mapping a two-dimensional plasma density distribution without causing much plasma disturbances. It follows that instantaneous mapping and its temporal evolution can be obtained. This diagnostic technique was investigated in detail.
Dual Function of Thin MoO3 and WO3 Films as Negative and Positive Resists for Focused Ion Beam Lithography
Authors: Hashimoto Masahiro , Watanuki Shinichi , Koshida Nobuyoshi , Komuro Masanori , Atoda Nobufumi
Published: October 2002

Fine patterning and metallization technologies have been studied using a combination of refractory metal oxide ( MoO3 and WO3) resists and Ga+ focused ion beam (FIB) lithography. In this work, it is demonstrated that depending on the preparation condition of the films, these thin oxide films act as either a negative or a positive resist with high-contrast capability. According to the results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, the negative resist mechanism is possibly due to an FIB-induced structural change from the amorphous to the ordered state, and the positive resist mechanism is due to a change from the polycrystalline to the disordered state. In both the negative and positive cases, the delineated patterns can be directly reduced to fine Mo or W wires. The potential applications of the observed dual function of oxide resists are also discussed.
Liquid Gold-Antimony Ion Sources
Authors: Yasuhito Gotoh Yasuhito Gotoh , Hiroshi Tsuji Hiroshi Tsuji , Junzo Ishikawa Junzo Ishikawa
Published: October 2002

The mass spectra of ion beams extracted from the impregnated-electrode type liquid gold-antimony ion sources have been investigated. Either eutectic alloy Au66Sb34 or intermetallic compound AuSb2 was used as the source material. The mass spectra were studied as a function of source current or as a function of source temperature, to investigate the behavior of Sb atoms. Analysis of liquid flow and evaporation within the ion source demonstrated that the alloy composition at the ionization point was determined by selective evaporation of Sb atoms, especially for the AuSb2 ion source. Relative intensities of multiply charged monomer ions strongly depended on the estimated concentration of Sb at the ionization point, which determined the evaporation field strength. Also, relative intensities of molecular ions were almost proportional to the estimated concentration of Sb. The present results indicated that ion formation in the liquid gold-antimony ion sources was dominated by the alloy composition at the ionization point. As a result, Au66Sb34 was found to be the preferred material.
Proposed Method to Produce a Highly Polarized e+ Beam for Future Linear Colliders
Authors: Toshiyuki Okugi Toshiyuki Okugi , Yoshimasa Kurihara Yoshimasa Kurihara , Masami Chiba Masami Chiba , Akira Endo Akira Endo , Ryousuke Hamatsu Ryousuke Hamatsu , Tachisige Hirose Tachisige Hirose , Tetsurou Kumita Tetsurou Kumita , Tunehiko Omori Tunehiko Omori , Yasunori Takeuchi Yasunori Takeuchi , Masakazu Yoshioka Masakazu Yoshioka
Published: October 2002

We propose a method to produce a spin-polarized e
+ beam using e
+
e
- pair-creation by circularly polarized photons. Assuming Compton scattering of an unpolarized e
- beam and circularly polarized laser light, scattered γ-rays at the high end of the energy spectrum are also circularly polarized. If those γ-rays are utilized to create e
± pairs on a thin target, the spin-polarization is preserved for e
+'s at the high end of their energy spectrum. By using the injector linac of Accelerator Test Facility at KEK and a commercially available Nd:YAG pulse laser, we can expect about 105 polarized e
+'s per second with a degree of polarization of 80% and a kinetic energy of 35–80 MeV. The apparatus for creation and measurement of polarized e
+'s is being constructed. We present new idea for possible application of our method to future linear colliders by utilizing a high-power CO2 laser.
Brief Measurement of Diffusion Profiles of Deep Impurities by Moving Schottky Contact
Authors: Masami Morooka Masami Morooka , Shinya Fukasako Shinya Fukasako
Published: October 2002

Long-range diffusion profiles of deep impurities, such as gold in silicon are usually obtained by repeating capacitance measurements after each removal of a considerable surface layer followed by fabrication of a Schottky junction on the surface. However, this method is time-consuming. By moving the Schottky electrode on an angle-lapped surface, the profiles have been obtained in less than one-tenth of the time required using the usual method.
Atomic Force Microscopy of Cracks on Si(100) and GaAs(100) Caused by Vickers Indenter
Authors: Misawa Guento , Yamada Hirofumi , Yutaka Seino Yutaka Seino , Kan Nakayama Kan Nakayama
Published: October 2002

It is very important to know the minimum value of the micro-Vickers indentation load when indents with cracks are obtained. Atomic force microscope imaging of cracks around indents made on both Si(100) and GaAs(100) by an indenter is described. The indents made with an applied load of 50 mN were pyramidal depressions of about 3 µ m×3 µ m at the top and a depth of about 0.4 µ m. The observed cracks on Si were meandering curves starting from the area near the corners of the indents and were steps with the maximum height of nearly 100 nm. The cracks are longest when their directions are parallel to <011>, and crack length decreases directions are the closer to <010>. In contrast to Si, straight cracks as ridges with the height of 10 nm to 30 nm were also observed in GaAs. They were isolated from the indent and almost parallel to the <010> or <011> orientation of the crystal.
Dependence of Signals from Embossed Recording Fields and Grooves on Filling of Aperture of Objective Lens
Authors: Hideharu Takeshima Hideharu Takeshima , Hidemi Yoshida Hidemi Yoshida
Published: October 2002

The dependence of signals from embossed recording fields and grooves on the filling of the aperture of the objective lens was studied using a simulation based on a scalar diffraction method. The results indicated that this dependence is too large to ignore and consequently, the difference in the filling D/W between testers should be considered for the correlation between testers.
High-Mobility Thin-Film Transistor Fabricated Using Hydrogenated Amorphous Silicon Deposited by Discharge of Disilane
Authors: Yamamoto Shigeichi , Junji Nakamura Junji Nakamura , Masatoshi Migitaka Masatoshi Migitaka
Published: October 2002

Plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon (a-Si:H) film was investigated with emphasis on the effect of disilane flow rate. A coplanar thin-film transistor (TFT) was fabricated using this a-Si:H film. Silicon-hydrogen bond content in the a-Si:H film was measured by infrared absorption spectroscopy. With decrease in the disilane flow rate from 3.0 cm3/min to 1.5 cm3/min, the maximum field-effect electron mobility (µ FE) of the TFT which depends on the gate voltage increased from 3.3 cm2/( V·s) to 4.9 cm2/( V·s), accompanied by a reduction in the silicon-hydrogen bond content. There was a negative correlation between µ FE and the silicon-hydrogen bond content in the a-Si:H film. The improvement mechanism of µ FE was discussed in terms of the chemical structure of the a-Si:H film.
Correlation between Anomalous Peak Effect in Magnetic Hysteresis Loop and Nanoscale Structure for NdBa2Cu3O7-δ Single-Crystal Superconductor
Authors: Nakamura Masaru , Hirayama Tsukasa , Yamada Yasuji , Ikuhara Yuichi , Yuh Shiohara Yuh Shiohara
Published: October 2002

To investigate the correlation between an anomalous peak effect in the magnetic hysteresis ( M–H) loop and microstructure for the NdBa2Cu3O7-δ (Nd123) single-crystal superconductor, M–H loops were measured with a superconducting quantum interference device (SQUID) magnetometer, and microstructures were observed by transmission electron microscopy (TEM). A TEM image (observed from [001] direction) of the Nd123 single crystal, which has an anomalous peak in the M–H loop, shows a nanoscale modulated structure (tweedlike image). This crystal also has the twin structure, as observed by polarized optical microscopy. In contrast, the Nd123 crystal, which has shown no anomalous peak effect, was found to possess no modulated structure, but twin structure was observed. Therefore the nanoscale structure (the modulated structure) is considered to be responsible for the anomalous peak effect in the M–H loop. Moreover temperature independence of the anomalous peak field in M–H loops was confirmed. We conclude that the nanoscale modulated structure may act as effective pinning center when its length matches that of the vortex lattice spacing.
Diamagnetic Susceptibility of Rhombohedral Graphite
Authors: Kiyoshi Kawamura Kiyoshi Kawamura , Manabu Iwamoto Manabu Iwamoto
Published: October 2002

Magnetic susceptibility of three graphite specimens with different degrees of rhombohedral structure is measured between liquid helium and room temperatures. Diamagnetic susceptibility of rhombohedral graphite is evaluated as a function of temperature in this temperature range. The magnitude of the susceptibility for rhombohedral graphite is much larger than that for hexagonal graphite and the susceptibility is maximum at around 60 K. The experimental results are analyzed and satisfactorily interpreted in terms of the theory for rhombohedral graphite.
Overdrivability of Red Laser Diode Pulse Power for Recording on Direct Overwrite Magneto-Optical Disk
Authors: Ishii Koichiro , Saito Jun , Akasaka Hideki
Published: October 2002

We measured electric current and light power diagrams of red laser diodes with a pulse power condition, and performed a life test of red laser diodes with the pulse power condition. From these experimental results, we conclude that these red laser diodes are overdrivable in pulsing, far exceeding their specification of DC rated power. We also conclude that direct overwrite magneto-optical (DOW-MO) disks with red laser diodes can achieve next-generation large capacity, with current disk rotation speed, which means, a data transfer rate equal to or greater than that of the current disk memory.
Atomic Depth Distribution Analysis of In and Ga on Si(111) during Epitaxial Growth and New Surfactant-Mediated Epitaxy
Authors: Toshiro Yamanaka Toshiro Yamanaka , Shozo Ino Shozo Ino
Published: October 2002

Atomic depth distribution and growth modes of In and Ga on a Si(111) surface were studied by a method using reflection high-energy electron diffraction (RHEED) and total reflection angle X-ray spectroscopy (TRAXS). Indium was deposited on a Si(111)-√3×√3-Ga(1 ML) surface at room temperature. After 2 ML and 6 ML of In deposition, the peak positions and the shapes were similar in the glancing angle dependence of GaK emission. By the analysis of these measurements, the growth mode was concluded to be as follows. First, two layers of In grew on the Ga layer in an ordinary growth mode. After the third layer, however, In grew under the third Ga layer, resulting in a layer structure of (In2Ga)In
m
(m=1,2,3 ...). On other Ga-covered Si(111) surfaces, In grew in an ordinary growth mode.
Growth Temperature Window and Self-Limiting Process in Sub-Atomic-Layer Epitaxy
Authors: Ishida Masahiro , Yamashita Mitsutomi , Yoshio Nagata Yoshio Nagata , Yoshiyuki Suda Yoshiyuki Suda
Published: October 2002

We have recently proposed a sub-atomic-layer epitaxy (SALE) technique by which Si is grown submonolayer-by-submonolayer from Si2H6 on Si(001). In this technique, Si submonolayer adsorption and surface thermal excitation are repeated alternately and an atomically flat surface is obtained in every growth cycle. In this work, SALE growth has been carried out using resistive substrate heating and Ar+ laser irradiation for the thermal surface excitation and the role of the laser irradiation and the relationship between the growth conditions and the growth mode have been quantitatively investigated. The results indicate a substrate temperature window of ∼17±4° C the presence of which has been interpreted in terms of a self-limiting process in the SALE growth. When 5–7 Ω· cm p-type Si(001) substrate is used, a change of the laser power by 0.2 W shifts the substrate temperature window by ∼10±4° C which is in reasonable agreement with the value of ∼12° C estimated using the result of thermally decomposed CVD growth, indicating that the laser irradiation has primarily a thermal effect. The growth mode is controlled by the surface temperature which is controlled by the combination of the Ar+ laser irradiation and the resistive heating.
Improvement of RIKEN 18 GHz Electron Cyclotron Resonance Ion Source using Aluminum Tube
Authors: Nakagawa Takahide , Miyazawa Yoshitoshi , Hemmi Masatake , Chiba Toshiya , Inabe Naohito , Kase Masayuki , Kageyama Tadashi , Kamigaito Osamu , Akira Goto Akira Goto , Yasushige Yano Yasushige Yano
Published: October 2002

We measured the beam intensity of highly charged argon and krypton ions covering the inner wall of a plasma chamber with an aluminum tube. The beam intensity was enhanced strongly and gas mixing was found to be unnecessary.
Applications of Aluminium Nitride Films Deposited by Reactive Sputtering to Silicon-On-Insulator Materials
Authors: Bengtsson Stefan , Bergh Mats , Choumas Manolis , Christian Olesen Christian Olesen , Kjell O. Jeppson Kjell O. Jeppson
Published: October 2002

Self-heating effects in silicon-on-insulator (SOI) devices limit the applicability of SOI materials in electronics in cases where high power dissipation is expected. Aluminium nitride as a potential candidate for buried insulator material in future SOI-structures is investigated. Reactive sputtering was used to manufacture the aluminium nitride films. The deposited films exhibit low stress and fairly low surface roughness. Further, resistivities above 1014 Ωcm as well as low thermal resistances were obtained. Interfacial problems at the interface between silicon and aluminium nitride were handled by adding a thin (a few nm) film of thermally grown silicon dioxide to that interface. The deposited films could be bonded both directly and through an electrostatic technique to silicon wafers. The presented results show that it is possible to make SOI structures with aluminium nitride as buried insulator by means of wafer bonding and subsequent etch-back.
Critical Current Densities and Irreversibility Fields of High Temperature Superconductors Sr2Ca2Cu3O7+δ and Sr2Can-1CunO2n+δF2+y (n=2, 3)
Authors: Yu Shan , Okuda Yuichi , Kawashima Tetsuya , Takayama-Muromachi Eiji
Published: October 2002

From the hystereses in DC magnetization loops, we determined critical current densities J
c and irreversibility fields B
irr of high temperature superconductors Sr2Ca2Cu3O7+δ (0223) and Sr2Ca

n
-1Cu

n

O2
n
+δF2+
y

(02(n-1)n- F, n=2, 3) prepared under high pressure. These phases have simple, thin blocking layers consisting of double SrO–SrO or SrF–SrF planes without any cations between them. J
c and B
irr of 0223 were larger than those of 0223-F, which seems to reflect the difference in the O-based and F-based blocking layers. The J
c and B
irr values obtained for the three phases were comparable to or even smaller than those of Hg-1223 and (Bi, Pb)-2223, in spite of their small spacings between the CuO2 multilayers.
A 35-Series Superconducting Quantum Interference Device Array for High-Dynamic-Range Magnetic Measurements
Authors: Uehara Kunio Kazami , Hisashi Kado Hisashi Kado
Published: October 2002

A 35-Series Superconducting Quantum Interference Device Array has been developed for a magnetometer with a high dynamic range. The coherence of each SQUID was observed in a double-shielded tube made of cryoperm and lead; a maximum voltage swing of 2 mV and flux noise of 0.6 µΦ0/√ Hz were obtained. The nonuniform inductance of the SQUIDs in the array, which causes Φ–V curve modulation, is decreased by using dummy SQUIDs at each end of the array. A gradiometer for biomagnetic measurement was constructed using a 35-SQUID array and a 10×10-mm planar pick-up coil. A magnetic-field sensitivity of 5.4 fT/√ Hz, a maximum slew rate of 1.9 mT/s, and a maximum feedback amplitude of ±2.23 µ T were achieved by using a direct-coupled flux-locked-loop circuit. The dynamic range of the magnetometer input field was ±4.13×108 √ Hz.
Optical Density Dependence of Write/Read Characteristics in Photon-Mode Photochromic Memory
Authors: Tsuyoshi Tsujioka Tsuyoshi Tsujioka , Minoru Kume Minoru Kume , Masahiro Irie Masahiro Irie
Published: October 2002

When photobleaching reactions are used for writing in a photochromic optical memory, the initial optical density in the recording layer plays an important role in the various write/read characteristics; i.e., secondary harmonics, repeatedly readout characteristics, and crosstalks in a multi-wavelength recording. Better characteristics, that is, lower secondary harmonics, higher readout repeatability and lower nonlinear component of crosstalks, were obtained for media with higher optical density.
Tuning Range of a CW Cr 3+:LiSAF Laser Spectrally Narrowed by an Auxiliary Cavity
Authors: J. Vasa Nilesh , Hongye Sui Hongye Sui , Husayin Parhat Husayin Parhat , Tatsuo Okada Tatsuo Okada , Mitsuo Maeda Mitsuo Maeda , Osamu Uchinno Osamu Uchinno
Published: October 2002

A cw \LiSAF laser was spectrally narrowed by a dispersive feedback from an auxiliary cavity coupled externally to a main cavity. The effect of a degree of feedback on spectral narrowing operation was examined. A single-mode operation using a diffraction grating as a feedback element near grazing incidence angle was obtained.
Energetically Stable Conformations of Nylon 66 and Nylon 6 Molecules in Crystals
Authors: Itoh Takashi , Yamagata Tetsuya , Hasegawa Yuka , Masato Hashimoto Masato Hashimoto , Takashi Konishi Takashi Konishi
Published: October 2002

Intramolecular interaction energies are calculated for nylon 66 and nylon 6 with the amide planes fixed, rotating all skeletal bonds of hexamethylene moiety of nylon 66 and those of pentamethylene moiety of nylon 6. Five stable conformations with an inversion center are found to exist for nylon 66, while only the all-trans conformation is shown to be stable for nylon 6. This is consistent with the fact that the phase transition is observed only in nylon 66 crystal.
Atomic Layer Epitaxy Growth of ZnSe on (100) GaAs Using Metalorganic Vapor-Phase Epitaxy System
Authors: Chin-Tsar Hsu Chin-Tsar Hsu
Published: October 2002

The atomic layer epitaxy (ALE) growth of ZnSe is successfully carried out on (100) GaAs substrates at 100–200° C by the use of a metalorganic vapor-phase epitaxy system. The growth rate per cycle is strongly dependent on the substrate temperature. The self-limiting growth of one monolayer per cycle is obtained in the wide substrate temperature range of 100–200° C. Double-crystal X-ray pattern shows that the lattice constant of ZnSe epilayer is 5.69 Å. The surface morphologies are smooth and mirrorlike. The photoluminescence spectrum shows an emission at 443 nm at 77 K.