bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of the p+ poly-Si Gate Fabricated Using the As Preamorphization Method
Authors: Kim Yeo Hwan , Kwon Sang Jik , Kuk Jin Chun Kuk Jin Chun , Jong Duk Lee Jong Duk Lee
Published: October 2002

In a deep submicron p-channel metal oxide field effect transistor (PMOSFET), the importance of the p+ poly-Si gate with less boron penetration and higher conductivity increases. With As implantation prior to B+ implantation, the conductivity of the p+ poly-Si gate was improved and the boron penetration was suppressed. These phenomena can be attributed to the enhancement of the grain growth in the As-preamorphized film and the retarded boron diffusion during annealing. DC conductivity of the film preamorphized by As+ ions at 180 keV and 4×1014 cm-2 was about 36% higher than that of the B implanted film without As preimplantation, in spite of the carrier compensation effect. Cross-sectional transmission electron microscopy (XTEM) micrographs show the bilayer with an upper layer of larger grain size ( ∼0.22 µm) and a lower layer of smaller grain size ( ∼0.03 µm) in the preamorphized and annealed film.
Structures and Properties of (ZnS)n(ZnSe)m (n=1–4) Ordered Alloys Grown by Atomic Layer Epitaxy
Authors: Fujiwara Hiroyuki , Toshiyuki Nabeta Toshiyuki Nabeta , Isamu Shimizu Isamu Shimizu
Published: October 2002

For the first time, two types of ordered alloys, (ZnS)

n

(ZnSe)12
n

( n=1–4) and (ZnS)3(ZnSe)

m

( m=12–72), were grown on GaAs substrates at low temperature (T=200° C) by atomic layer epitaxy (ALE). Hydrogen-radical-enhanced chemical vapor deposition (HRCVD) was used to deposit the atomic layers. Layered structures were confirmed by X-ray diffraction of the deposited films, which showed satellite peaks at the expected values. Photoluminescence (PL) measurements indicate a high quantum efficiency with a single, narrow emission band near the bandgap energy. Despite the large lattice deformation, deep-level emission intensity was negligible in a wide compositional range of the ordered alloys, (ZnS)3(ZnSe)

m

. The photoluminescence peak energies shift systematically with changes in the selenium-to-sulfur ratio of these ordered alloys. The (ZnS)

n

(ZnSe)12
n

ordered alloys grow coherently with excellent structural and optical properties and exhibit low defect densities.
Analytical DC Model for a-Si:H Thin-Film Transistors Using Effective Temperature Approach
Authors: Shiao-Shien Chen Shiao-Shien Chen , James B. Kuo James B. Kuo
Published: October 2002

In this paper, we present an analytical dc model for a-Si:H thin-film transistors considering deep and tail states simultaneously. Using an effective temperature approach, the localized deep and tail states have been considered in the dc model such that no approximations are needed. As verified by the published data, this analytical dc model provides an accurate prediction of the drain current characteristics of an a-Si:H thin-film transistor.
Fabrication of a-axis Oriented YBa2Cu3Ox/PrGaO3/a-axis Oriented YBa2Cu3Ox Trilayer Films
Authors: Masashi Mukaida Masashi Mukaida , Shintaro Miyazawa Shintaro Miyazawa
Published: October 2002

This paper reports the fabrication of a-axis oriented YBa2Cu3O

x

/PrGaO3 insulating barrier/ a-axis oriented YBa2Cu3O

x

trilayer films by in-situ pulsed-laser deposition. A cross sectional transmission electron microscopy (XTEM) analysis of the junctions verifies that the ultrathin PrGaO3 insulating barrier does not form islands between the base and the counter electrode of YBa2Cu3O

x

films and the a-axis oriented YBa2Cu3O

x

grows right on the insulating PrGaO3 ultrathin (30 Å) film without any c-axis oriented or disordered YBa2Cu3O

x

layer. Excellent surface coverage of the base electrode of the YBa2Cu3O

x

thin film is considered to result from lattice matching and the similarity of the crystal structure. Lattice matching perovskite insulators with the same thermal expansion coefficient are attractive for use as the insulating barrier for superconductor/insulating barrier/superconductor (SIS) junctions.
Real-Time Observation of the Interaction between Flux Lines and Defects in a Superconductor by Lorentz Microscopy
Authors: Harada Ken , Kasai Hiroto , Matsuda Tsuyoshi , Yamasaki Masami , John E. Bonevich John E. Bonevich , Akira Tonomura Akira Tonomura
Published: October 2002

Flux lines in a Nb thin film at 4.5 K were observed by using a 300-kV field-emission transmission electron microscope equipped with a TV system. When the magnetic field applied to the film was suddenly changed, flux lines moved until arriving at an equilibrium state by hopping from one pinning center to another. Frame-by-frame observation of videotape recorded with a time resolution of 1/30 s revealed how individual flux lines behaved when they came across subgrain boundaries, and interacted with the boundaries.
Strain Effect on 630 nm GaInP/AlGaInP Multi-Quantum Well Lasers
Authors: Kamiyama Satoshi , Uenoyama Takeshi , Masaya Mannoh Masaya Mannoh , Kiyoshi Ohnaka Kiyoshi Ohnaka
Published: October 2002

We theoretically analyzed the GaInP/AlGaInP strain effect of compressive- and tensile-strained multi-quantum well (MQW) lasers with the lasing wavelength of 630 nm and under a fixed optical confinement condition. Since the compressive-strained MQW has the weaker valence subband mixing, it can greatly reduce the hole band density of states, and results in the reduction of the threshold current. On the contrary, the tensile strain increases the density of states, so the strain of up to 0.5% has no effect in reducing the threshold current despite the large matrix element. In the comparison with the experimental results, however, the threshold current density of the compressive-strained MQW obtained in our calculation is much lower than that in the experimental results. It seems that the nonradiative recombination current, which is not included in our calculation, increases in the compressive-strained MQW because of its narrow well width.
Parametric Studies on the Laser-Diode-Pumped, Thermal-Lensing-Compensated, Mode-Locked, Q-Switched Nd:YAG Laser
Authors: Ohmi Masato , Naito Kenta , Ishikawa Koji , Akatsuka Masanori , Sato Tsuyoshi , Yamanaka Masanobu , Masahiro Nakatsuka Masahiro Nakatsuka , Sadao Nakai Sadao Nakai
Published: October 2002

The parametric studies of a laser-diode (LD)-pumped, acousto-optic (AO)-mode-locked and Q-switched Nd:YAG laser were carried out. Adequate compensation for the thermal lensing in the longitudinally pumped laser rod was provided by analyzing the spot size in the astigmatically compensated cavity. The width of the mode-locked pulse with 0.5 nJ output energy per pulse was elongated to 910 ps by means of an intracavity etalon. Good stabilities of the output energy (±3%) and the peak power (±5%) were obtained, which are comparable to those of the flash-lamp-pumped mode-locked Q-switched lasers.
Long-Wavelength Receiver Optoelectronic Integrated Circuit on 3-Inch-Diameter GaAs Substrate Grown by InP-on-GaAs Heteroepitaxy
Authors: Mihashi Yutaka , Goto Katsuhiko , Ishimura Eitaro , Miyashita Miyo , Shimura Teruyuki , Nishiguchi Harumi , Kimura Tatsuya , Tetsuo Shiba Tetsuo Shiba , Etsuji Omura Etsuji Omura
Published: October 2002

A monolithic long-wavelength receiver optoelectronic integrated circuit (OEIC), which integrates an InGaAs PIN-photodiode (PD) and a GaAs field-effect transistor (FET), has been successfully fabricated on a 3-inch-diameter GaAs substrate using InP-on-GaAs heteroepitaxy, by metalorganic chemical vapor deposition (MOCVD) and conventional GaAs-IC process technology. The epitaxial quality of the PD layer has been improved by use of a low-temperature-grown buffer layer, thermal cyclic annealing and an InGaAs/InP strained-layer superlattice. The integrated PD has low dark current of 10 nA at -5 V bias voltage, and exhibited stable operation at 175°C. The fabricated receiver OEIC has 1.4 GHz bandwidth and sensitivity of -28.1 dBm at the transmission rate of 622 Mb/s with bit error rate of 10-9, which is applicable to practical subscriber optical communication systems.
Structural Formula and Gas-Sensitive Properties of α-Fe2O3(SO4
-) Ceramics
Authors: He Fangjun , Han Jisheng , Zheng Ying , Yu Hui , Wang Yong
Published: October 2002

The relationship between SO4
- and the structure of α-Fe2O3(SO4
-) ceramics, and gas-sensitive properties were studied by means of temperature-resistant properties and infrared spectra. We concluded that α-Fe2O3 became gas-sensitive by adding some other ions with a similar structure.
Dielectric Response of Ferroelectric Liquid Crystal Cells
Authors: Panarin Yuri P. , Xu Huan , Seamus T. Mac Lughadha Seamus T. Mac Lughadha , Jagdish K. Vij Jagdish K. Vij
Published: October 2002

The dielectric response of a number of homogeneously aligned FLC cells has been investigated. Several relaxation processes exhibiting behaviour with different relaxation times are found for the first time. These are identified with the structure of the smectic layers in the cell and the parameters of the FLC mixtures. The assignment of these processes is based on a combination of electro-optic and dielectric investigations.
Computer Simulation of Growth Process of Binary Quasi Crystal
Authors: Sasajima Yasushi , Adachi Katsumi , Tanaka Hideki , Ichimura Minoru , Masanori Itaba Masanori Itaba , Satoru Ozawa Satoru Ozawa
Published: October 2002

We performed Monte Carlo simulation of the aggregation process of a two-component Lennard-Jones system on the two-dimensional (2D) Penrose lattice for the purpose of studying the details of the creation and growth process of quasi crystals. We adopted the potential parameter values proposed by Widom et al. [Phys. Rev. Lett. 58 (1987) 706]. The present simulation clarified that the stability of the formed quasi crystals depends on temperature and the strength of the potential and that the transition from solid state to liquid state occurs when the value of the inverse of the dimensionless temperature is approximately 4.0.
The Study of Ultrathin Tantalum Oxide Films before and after Annealing with X-Ray Photoelectron Spectroscopy
Authors: Muto Akiko , Yano Fumiko , Yasuhiro Sugawara Yasuhiro Sugawara , Shimpei Iijima Shimpei Iijima
Published: October 2002

The effects of post-deposition annealing on the microstructure of tantalum oxide ( Ta2O5) deposited on Si are evaluated by means of X-ray photoelectron spectroscopy. With the peak decomposition technique and the angle-resolved X-ray photoelectron spectroscopy (ARXPS) method we found that there is SiO2 layer and Ta suboxide at the interface. By using a simple two-layer model, the thickness of both the Ta2O5 layer and the interfacial SiO2 layer could be evaluated. Investigating Ta2O5 films this way before and after annealing revealed that annealing has the following effects on the interfacial reaction. With post-deposition annealing under O2, Ar, or N2 gas, the Si substrate is oxidized by oxygen from the Ta2O5 layer. The Ta2O5 is partly reduced and N2 gas activates this reaction. The thickness of the interfacial SiO2 layer is reduced by nitridation of the Si substrate.
Preheating Effects of Melt on Nucleation and Growth of Oleic Acid Polymorphs
Authors: Noriyuki Yoshimoto Noriyuki Yoshimoto , Kiyotaka Sato Kiyotaka Sato
Published: October 2002

Preheating effects of melt on nucleation and growth of oleic acid ( cis-ω 9-octadecenoic acid) polymorphs were studied. The nucleation rate of the metastable α-form was significantly influenced by the preheating temperature of the melt. Degree of supercooling (ΔT) and induction time (τ) for crystallization of the α-form increased with increasing preheating temperature of the melt from 20°C to 80°C. However, there was no clear pre-heating effect on the most stable β-form. This may suggest that differences in the melt structure which have been previously reported by Iwahashi et al. [J. Phys. Chem. 95 (1991) 445] influence the nucleation rates of the α-form. On the contrary, the preheating effect on growth rate of the α-form was not appreciable. This could indicate a modification of the melt structure at the solid-liquid interface of oleic acid crystals.
Deposition of WSix Films from Preactivated Mixture of WF6/SiH4
Authors: Saito Takeyasu , Shimogaki Yukihiro , Egashira Yasuyuki , Komiyama Hiroshi , Yuyama Yoshiaki , Sugawara Katsuro , Takahiro Katsumi , Nagata Shinji , Yamaguchi Sadae
Published: October 2002

WSi

x

films were formed on a substrate from thermal chemical vapor deposition (CVD) of WF6 and SiH4. Chemical reactions were initiated upstream of the substrate by a preheater, and chemical reactions are radical chain reactions which produce preactivated cursors that are deposited, causing film growth. Because chemical reactions occur upstream of the substrate, film formation occurred even at temperatures as low as 40° C. Compared with films deposited at the same substrate temperature, without preheating, the Si content increased by 50%, the interfacial concentration of residual fluorine decreased by one order of magnitude, and the sticking probability of the precursors on the substrate was the same. The sticking probability was shown to depend solely on the substrate temperature, even for varying degrees of preheating. Deposition on a low-temperature substrate of the preactivated precursors provides a means to deposit conformal WSi

x

films with low interfacial concentration of fluorine.
Patterning Characteristics of Oblique Illumination Optical Lithography
Authors: Horiuchi Toshiyuki , Takeuchi Yoshinobu , Tamechika Emi , Mimura Yoshiaki , Seitaro Matsuo Seitaro Matsuo , Katsuhiro Harada Katsuhiro Harada
Published: October 2002

The patterning characteristics of oblique illumination lithography are investigated. When the reticle is illuminated obliquely, the pattern widths corresponding to the opaque parts of the reticle are apt to become thinner than those replicated by conventional optical lithography. This characteristic is verified by both analysis of the projected image intensity distribution and some patterning experiments. The double harmony of the periodical pattern image plays an important role in defining the pattern widths. We concluded that the lack of the double harmonic light waves caused the pattern shrinkage in the case of oblique illumination lithography. In recognizing the above differences, the exposure dose can be suitably controlled so as to attain high resolution and large focus latitude.
Improvement of the Uniformity of Tungsten/Carbon Multilayers by Thermal Processing
Authors: Oshino Tetsuya , Murakami Katsuhiko , Nakamura Hiroshi , Masayuki Ohtani Masayuki Ohtani , Hiroshi Nagata Hiroshi Nagata
Published: October 2002

Tungsten/carbon (W/C) multilayers deposited by ion beam sputtering were annealed by focused infrared rays in vacuum and investigated by X-ray diffraction. The periodic spacing increased with the annealing temperature between 200 and 600° C after only 4-min annealing time, and the ratio of increase was about 0.01%/° C. A new control method of the periodic spacing distribution by thermal processing was suggested, where several areas of the sample were annealed at different temperatures. The periodic spacing distribution, which was a convex profile for the as-prepared W/C multilayer films, became uniform and the periodic spacing difference compared with the designated one was within 0.06 nm.
Investigations of Pressure and Temperature Effects on Gelation Process of Egg White by Time-Resolved Turbidimetric Measurements
Authors: Haruichi Kanaya Haruichi Kanaya , Kazuhiro Hara Kazuhiro Hara , Atsushi Nakamura Atsushi Nakamura , Nobuyasu Hiramatsu Nobuyasu Hiramatsu , Kazumi Matsushige Kazumi Matsushige
Published: October 2002

Dynamical properties of the gelation process of egg white under simultaneous pressure and heat treatments were investigated by measuring the transmitted light spectra. It was found that pressures up to 180 MPa can suppress the heat-induced gelation. In a pressure-jump experiment, the transmitted light intensity rapidly increased on the application of pressure, then decreased gradually, which indicates that dissociation of the protein clusters occurs before polymerization.
High Frequency Resonant Electromagnetic Generation and Detection of Ultrasonic Waves
Authors: Kawashima Katsuhiro , Wright Oliver B. , Hyoguchi Takao
Published: October 2002

High frequency resonant mode electromagnetic ultrasonic generation and detection in metals is demonstrated at frequencies up to ∼150 MHz with various metal sheet samples. Using a unified theory of the generation and detection process, it is shown how various physical quantities can be measured. The sound velocity or thickness of the sheets can be derived from the resonant frequencies. At resonance the detected amplitude is inversely proportional to the ultrasonic attenuation of the sample, whereas the resonance half-width is proportional to this attenuation. We derive the ultrasonic attenuation coefficient from the half-width, and show how the grain size of the material can be probed. In addition we present results for thin bonded sheets, and show how a measure of the bonding or delamination can be obtained. This high frequency resonant method shows great promise for the non-destructive evaluation of thin sheets and coatings in the sub- 10-µm to 1-mm thickness range.
Studies of NH3 Thermal Nitridation of Ultrathin Si-Oxide Films on Si using Photoemission Spectroscopy with Synchrotron Radiation
Authors: Ken-ichi Yamamoto Ken-ichi Yamamoto , Masatoshi Nakazawa Masatoshi Nakazawa
Published: October 2002

The NH3 thermal nitridation process of ultrathin Si-oxide films on a Si(100) substrate has been investigated by in situ X-ray photoelectron spectroscopy using synchrotron radiation. Silicon oxide films with a thickness of about 0.7 nm are exposed to NH3 gas at 1.3×10-4 Pa at substrate temperatures from room temperature to 800° C. Nitridation occurs above 800° C, which is the desorption temperature of Si oxides. In the initial stage of nitridation, the Si substrate near the interface is nitrided and the nitridation components of Si1+–Si4+ ( Si

n
+ means the chemical bonding state bonded to n nitrogen atoms) are generated. The number of Si4+ component increases as the thickness of the nitrided film increases, and when the Si-nitride films are 1 nm thick, it contains no oxygen atoms.
Guided Acoustic Phonons in Quantum Wires: Theory of Phonon Fiber
Authors: Norihiko Nishiguchi Norihiko Nishiguchi
Published: October 2002

Acoustic phonon modes confined to a GaAs cylindrical quantum wire within AlAs are analytically investigated within the context of an elastic continuum model. Elastic properties are assumed to be isotropic for both materials for mathematical convenience. The displacement vector is expressed by the scalar potential and two vector potentials. The confined acoustic phonon modes are classified into three types according to the rotational symmetry of the potential functions: dilatational, torsional, and flexural modes. Dispersion curves of the modes show phonon subband structures with finite cutoff frequencies due to confinement of waves in lateral directions. The density of the confined phonon modes accordingly appears as staircaselike structures.
Simulation of Ultrasonic Beam in Vortex
Authors: Haitao Pan Haitao Pan , Shigeo Ohtsuki Shigeo Ohtsuki
Published: October 2002

The shell function method is extended and adapted to evaluate the acoustic pressure field in an arbitrary inhomogeneous and moving medium. In the case of an inhomogeneous and quiescent medium, the shell function method for computing the acoustic pressure field due to a finite source was developed using the principle of reciprocity. Based on the reciprocity in a moving medium, the extension is accomplished by investigating rays as originating from an imaginary point source located at the observation point, in the medium with reversed flow direction. Through a numerical example of evaluating the pressure field in a vortex produced by a disk source, it is shown that the shell function method gives an interpretation for the beam displacement with respect to the vortex.
Suppression of Irregularity in Frequency Response and Directivity of a Piezoelectric Polymer Film Hydrophone
Authors: Yasuhiro Nakamura Yasuhiro Nakamura , Takahiko Otani Takahiko Otani
Published: October 2002

The construction of piezoelectric polymer film hydrophones has been studied in order to suppress irregularities in hydrophone frequency response and directivity characteristics caused by the formation of induced surface waves on the backing material. A polyvinylidene fluoride (PVDF) hydrophone having a cylindrical baking material rounded at its edge is shown to have flat frequency response in the range of 100 kHz to 10 MHz and to have good directivity in agreement with piston motion theory.
Propagation Characteristics of Shear-Horizontal Plate Modes on Water-Loaded LiNbO3
Authors: Kohji Toda Kohji Toda , Akihiro Sawaguchi Akihiro Sawaguchi
Published: October 2002

Propagation characteristics of shear-horizontal (SH) plate modes along a water-loaded surface of a rotated Y-cut X-propagation LiNbO3 thin plate are numerically analyzed from the viewpoint of the operation performances of an interdigital transducer. The phase velocity, electromechanical coupling constant, mode conversion efficiency and transducer efficiency are given as a function of the product of frequency and substrate thickness. The velocities obtained from the measured center frequencies of the SH wave devices are in good agreement with the numerically analyzed results. The zeroth-order symmetrical mode has a very high coupling constant of 20% for rotation angles of around 30° under a very low mode conversion value of below 1%.
Characteristics of AlN Thin Films Deposited by Electron Cyclotron Resonance Dual-Ion-Beam Sputtering and Their Application to GHz-Band Surface Acoustic Wave Devices
Authors: Okano Hiroshi , Tanaka Naoki , Hirao Yasuhiro , Kobayashi Yasumi , Kenichi Shibata Kenichi Shibata , Shoichi Nakano Shoichi Nakano
Published: October 2002

A (001) plane of hexagonal aluminum nitride (AlN) has been deposited on R-plane sapphire ((1 1̄·2)Al2O3) with inclination of about 26° against the substrate by electron cyclotron resonance (ECR) dual-ion-beam sputtering. A shear horizon (SH) wave as well as a modified Rayleigh wave could be excited on this AlN film. The phase velocities of the SH wave (V
SH) and Rayleigh wave (V
R) were 6000∼6730 m/s and 5600∼5950 m/s, respectively. V
R has no effect on the propagation direction. However, V
SH has considerable influence on the propagation direction, and becomes maximum at the propagation direction of 45 degrees against [12·0]AlN. The insertion loss and temperature coefficient of delay time (TCD) of the 1.21-GHz-band two-port-type resonator using SH waves were 7.5 dB and 35.4 ppm/°C, respectively. These values are acceptable for practical use.
Surface Acoustic Wave Filter Composed of Interdigitated Interdigital Transducers and One-Port Resonators
Authors: Yatsuda Hiromi , Yoshihiko Takeuchi Yoshihiko Takeuchi , Taira Horishima Taira Horishima
Published: October 2002

This paper describes a design method for low-loss surface acoustic wave (SAW) filters with a large stop-band attenuation. The method employs a conventional interdigitated interdigital transducer (IIDT) SAW filter and conventional one-port SAW resonators, which are constructed on one chip and connected electrically. The resonators provide a large attenuation in a specified stop band. On the other hand, the resonators act as an element in a matching circuit for the IIDT SAW filter in the passband. An 880 MHz filter was designed and fabricated according to the proposed method. The side-lobe attenuation of 45 dB in the specified stop band and the insertion loss of 2.5 dB in the passband were realized.
Bleustein-Gulyaev-Shimizu Wave Propagating under Metallic Gratings of Finite Thickness
Authors: Ken-ya Hashimoto Ken-ya Hashimoto , Masatsune Yamaguchi Masatsune Yamaguchi
Published: October 2002

The discrete Green function theory, which takes the mass-loading effect into consideration, is developed, and the propagation and excitation characteristics of a Bleustein-Gulyaev-Shimizu wave (BGSW) under metallic gratings of finite thickness are discussed. Acoustic fields in the grating electrodes are expressed as a sum of analytical solutions, while those in a substrate, as the effective acoustic impedance matrix. The effective permittivity for the grating structure, which gives the discrete Green function, is derived by minimising a functional defined by the acoustic fields at the boundary. Velocity dispersion of BGSW propagating on Al-grating/PZT-5H and Au-grating/PZT-5H structures is shown, and the mass-loading effect on the BGSW propagation and excitation is discussed.
Ultrasonic Butt Welding of Aluminum, Copper and Steel Plate Specimens
Authors: Tsujino Jiromaru , Ueoka Tetsugi , Yuki Fujita Yuki Fujita , Ichiro Watanabe Ichiro Watanabe
Published: October 2002

Characteristics of ultrasonic butt welding of the same and of different metal plates are 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. Welding specimens of aluminum, copper and steel plates of 6 mm thickness are successfully joined end-to-end with weld strength almost equal to that of an aluminum specimen. The input power required for aluminum, aluminum and copper, and aluminum and steel plates are about 5 kW/cm2, 5.5 kW/cm2 and 3.5 kW/cm2, respectively. The measured temperature rise at the specimen side surface and elongation of the welded specimen during a tensile test correspond to weld strength. The hardness distributions along the weldment of welded specimens are measured and the maximum temperature rise in an aluminum welding specimen is estimated to be over 480°C from the reduction of hardness at a welding specimen surface.
Single-Resonance Longitudinal and Torsional Vibrator Combination-Type Motor: Improvement of Motor Characteristics
Authors: Masaharu Shimanuki Masaharu Shimanuki , Manabu Aoyagi Manabu Aoyagi , Yoshiro Tomikawa Yoshiro Tomikawa
Published: October 2002

The present paper deals with the single-resonance longitudinal and torsional vibrator combination-type motor, which is one of the ultrasonic motors with a relatively large torque. To improve the characteristics of this motor, the authors studied the calculation method of the resonance frequencies and designed the motor so that the resonance frequencies of the longitudinal and torsional vibrations were very close to the measured ones, because it was thought that the motor characteristics were largely affected by the degree of approximation of the resonance frequencies. Experimental results have proven that the prototype motor produced large torque with a maximum of 14.0 kgf·cm under a total electrical input power of 30 W; this value was 1.5 times as large as that reported previously. That is, it has been clarified that with sufficient degree of approximation of the resonance frequencies, as mentioned above, the output torque of the motor could be greatly improved; however, its efficiency (maximum of 13.1%) was maintained at almost the same value as before.
An Analysis on the Driving Force and Optimum Frequency of a Noncontact-Type Ultrasonic Motor
Authors: Yamayoshi Yasuhiro , Hirose Seiji , Shuji Sone Shuji Sone , Hisashi Nakamura Hisashi Nakamura
Published: October 2002

A Noncontact-type ultrasonic motor driven by the radiation pressure of the sound waves can be rotated well and miniaturized. In the previous study, the maximum revolution speed reached 4,000 rpm in the case of a small ultrasonic motor of 5 mm diameter and 0.5 mm thickness. In this paper, a consideration of the driving force of such a noncontact ultrasonic motor is described.
Measurement of Low-Frequency Ultrasonic Waves by Fraunhofer Diffraction
Authors: Yoshito Sonoda Yoshito Sonoda , Masanori Akazaki Masanori Akazaki
Published: October 2002

The application of the Fraunhofer diffraction method, which has been developed as a new means to identify long-wavelength plasma waves or fluctuations appearing in plasma nuclear fusion research machines, to the measurement of low-frequency ultrasonic waves propagating in air was theoretically and experimentally examined. It is experimentally demonstrated that a wave with a wave number of about 0.1 to 0.74 mm-1can be detected by using a visible laser. Such a wave number corresponds to a diffraction angle of 0.6 to 4.3 mdeg, which is much smaller than the standard value measured by the conventional diffraction method. Furthermore, it is shown that if a diverging probe beam is adopted, the wave position can be identified by measuring the spatial phase distribution of the diffracted wave.
Design of an Acoustical Imaging Operator Based on the Singular Value Decomposition Method
Authors: Murata Yorinobu , Minagawa Keiji , Yasutaka Tamura Yasutaka Tamura , Kiyohito Koyama Kiyohito Koyama
Published: October 2002

A new imaging operator has been developed for acoustical imaging using a 2ch m-sequence encoding array transducer. The new imaging operator has the ability to correct the poor orthogonal property of a transfer matrix. Moreover, images with many image points have been reconstructed by the new imaging operator. The new imaging operator has been composed on the basis of the singular-value decomposition (SVD) of the transfer matrix in the frequency domain. Characteristics of the new imaging operator are discussed by simulating the two-dimensional point spread functions (2-D PSFs). An image with a high dynamic range was obtained for a single object on the sampling image points by the method. Moreover, the method was able to reconstruct the image of the existing object outside the sampling image points.
Quality Improvement of Ultrasonic Diffraction Tomography Based on Knowledge of Background Velocity
Authors: Akira Yamada Akira Yamada
Published: October 2002

A reconstruction method in ultrasonic diffraction tomography aiming at the relaxation of the weak scattering condition was investigated. The method with a simple fast procedure was realized by effectively incorporating the background information into the conventional first-order Born reconstruction based on the assumption that the background velocity variation of the object is known. Simulation and experimental results using cylindrical test objects were shown. As a result, the validity of the present method was demonstrated to satisfy the practical requirement to a certain extent.
Water Bottom Material Discrimination Using Multilayered Neural Network
Authors: Kouno Toshiyoshi , Seiichi Motooka Seiichi Motooka , Nobuyuki Takano Nobuyuki Takano
Published: October 2002

The measurement to establish the discrimination method of water bottom material using the pulse echo method and neural network data processing were performed in a model water bath. Furthermore, the optimum learning and discriminating conditions were studied in order to obtain a good discrimination result by restraining the changes in intensity level of the echo signals. It is concluded that optimum values of learning and discriminating data to be input to the multilayered neural network are the mean value of 6 datums for learning data and 20 mean values of 3 datums each for discriminating data.
Low-Temperature Formation of Palladium Silicided Shallow p+n Junctions Using Implant through Metal Technology
Authors: Lin Cheng-Tung , Pei-Fen Chou Pei-Fen Chou , Huang-Chung Cheng Huang-Chung Cheng
Published: October 2002

Excellent silicided shallow p+n junctions have been successfully achieved by the implantation of BF2
+ ions into thin Pd films on a Si substrate to a dose of 5×1015 cm-2 and subsequent low-temperature (as low as 500° C) furnace annealing. The formed junctions have been characterized for the respective implantation conditions. In this experiment, the implant energy plays the key role in obtaining a low leakage diode. Reverse current density of about 1 nA/cm2 and the ideality factor of about 1.03 can be attained by the implantation of BF2
+ ions at 100 keV and subsequent annealing at 600° C. The junction depth is about 0.08 µm, measured by the spread resistance method. As compared with the results of unimplanted specimens, the implantation of BF2
+ ions into a thin Pd layer can stabilize the Pd silicide film and prevent it from forming islands during high-temperature annealing. High-temperature stability of palladium silicides and the leakage current mechanism are also discussed in this report.
Formation of Cubic GaN on (111)B GaAs by Metal-Organic Vapor-Phase Epitaxy with Dimethylhydrazine
Authors: Kuwano Noriyuki , Kobayashi Kenki , Oki Kensuke , Miyoshi Seiro , Yaguchi Hiroyuki , Onabe Kentaro , Shiraki Yasuhiro
Published: October 2002

The microstructure of GaN grown on (111)B GaAs by a metal-orgnic vapor-phase epitaxy method has been examined by transmission electron microscopy. Trimethylgallium and dimethylhydrazine were used as the source materials. It was revealed that the GaN crystal has a zincblende structure and is formed heterogeneously penetrating into the GaAs substrate. In a GaN crystal, stacking faults propagate on {111} planes other than those normal to the growth direction.
Fabrication and Characterization of Nb–(Nb Nanoconstrictions)–NbN Short Weak Links
Authors: Abe Hiroya , Hamasaki Katuyoshi , Kazuaki Kojima Kazuaki Kojima , Masayuki Sasaki Masayuki Sasaki
Published: October 2002

We report the fabrication and characterization of thin-film Nb–(Nb nanoconstrictions)–NbN short weak links prepared by applying an electric field to an insulating Nb/MgO/NbN edge sandwich with an area of 0.2 µm2. The growth of Nb nanoconstrictions in the MgO ( ∼7 nm thick) insulator layer connecting two superconducting banks is assisted by electric field in liquid helium. For an interpretation of device quasiparticle characteristics, the Blonder, Tinkham and Klapwijk (BTK) theory [Phys. Rev. B 25 (1982) 4515] is used. The current-voltage curves and excess current-normal resistance products are found to agree closely with the BTK predictions by assuming two independent (series) normal metal-superconductor contacts. The two-level fluctuation (TLF) of conductance was apparently observed in the samples with Andreev reflection probability of A (E)≪1. For the samples with A (E)∼1, i.e., nearly clean contacts, no apparent TLF was observed in the frequency band up to 100 kHz.
Determination of Rotational Viscosity of Nematic Liquid Crystals from Transient Current: Numerical Analysis and Experiment
Authors: Masahiro Imai Masahiro Imai , Hiroyoshi Naito Hiroyoshi Naito , Masahiro Okuda Masahiro Okuda , Akihiko Sugimura Akihiko Sugimura
Published: October 2002

A simple method is presented for the determination of the rotational viscosity of nematic liquid crystals. Theoretical expressions for the rotational viscosity from transient displacement current in nematic liquid crystals are derived. The validity of the expressions is numerically examined. It is found that the rotational viscosity can be obtained with sufficient accuracy. The rotational viscosity of ZLI-2293 (Merck Ltd.) is measured at various temperatures by the present method.
Remote Plasma SiO2Deposition by Tetraethoxysilane with Chemically and Energetically Different Atomic Species
Authors: Wickramanayaka Sunil , Matsumoto Akinori , Nakanishi Yoichiro , Hosokawa Naokichi , Yoshinori Hatanaka Yoshinori Hatanaka
Published: October 2002

Thin films of SiO2are deposited using tetraethoxysilane (TEOS) as the source gas in remote rf (13.56 MHz) and microwave plasmas. Depositions were carried out using atomic and molecular radicals of different reactivities generated in O2, N2, H2, Ar and He plasmas. SiO2films could be fabricated only in the downstreams of O2, N2and Ar plasmas with the reaction of TEOS. SiO2was not produced by TEOS with the reaction of downstream of H2or He plasma. SiO2deposited with Ar plasma contains a small amount of C. The activation energy of film growth rate varies depending on the partially decomposed TEOS precursor density. Furthermore, the quality of SiO2films deposited with energetically different ground-state ( O(3P)) and excited-state ( O(1D)) atomic oxygen environments was comparatively studied. Films deposited in an excess O(1D) environment show better physical and electrical properties, though the yield of SiO2is independent of the state of the atom.
Preparation of Oriented Large Domains of Diacetylene Monolayer at the Air-Water Interface
Authors: Yamada Susumu , Hatta Eiji , Mukasa Kōichi
Published: October 2002

Large domains in a diacetylene derivative (10,12-pentacosadiynoic acid) monomer monolayer at the air-water interface were obtained by spreading a solution of relatively high concentration. Uniformly oriented large domains of over 20 mm×5 mm were prepared when the area of water surface was slowly increased by moving a barrier after the highly concentrated solution was spread on a small bounded water surface.
Asymmetric Thin Film of Poly(p-phenylene) Prepared by Vacuum Deposition
Authors: Asakura Toshihide , Toshima Naoki
Published: October 2002

The thin film, prepared by a vacuum deposition method from poly( p-phenylene) synthesized from benzene by a CuCl–AlCl3–O2 catalytic system, had an asymmetric property in its photo-luminescence spectra. Namely, the spectrum observed from the region near the surface had maximum emission peaks at 400–500 nm, while the spectrum observed from the region near the substrate had a maximum emission peak at wavelength above 600 nm. This asymmetric property was observed in the case of the film prepared with a low-temperature substrate. To the contrary, the thin film, prepared at high substrate temperature (150° C), or heat-treated (200° C, in N2, 1 h) after preparation, had no such asymmetric property. The asymmetric property was related to the surface crystallinity and probably the morphology of the film. The surface of the asymmetric film was almost structureless except for some structures resembling whiskers. The surface of the film without the asymmetric property, however, consisted of meshlike structure constructed by small round particles or a complicated meshlike structure.
New Silylation Bi-layer Resist System Employing Photochemical Selective Resist Silylation
Authors: Kotaka Yoshiaki Mimura
Published: October 2002

This paper describes a new silylation bi-layer resist system (SIBIS) that employs our previously reported photochemical selective silylation technique. Several different types of SIBIS are presented: normal-transfer SIBIS, image-reversal SIBIS, two-way normal-transfer/image-reversal SIBIS using the same resist materials, dry-development SIBIS, and SIBIS that uses an antireflective undercoating as a bottom layer. These SIBISs are applicable to optical, e-beam, and X-ray lithographies with proper selection of top-layer resist materials. This investigation primarily focuses on the top- and bottom-layer materials and silylation process conditions. Each of the SIBIS processes demonstrate fine pattern fabrication capability. The usefulness and superiority of SIBIS for LSI fabrication is confirmed.
SOI (Silicon-On-Insulator) for High Speed Ultra Large Scale Integration
Authors: Chenming Hu Chenming Hu
Published: October 2002

Bulk complementary metal-oxide-semiconductor (CMOS) technology scaling can not sustain the historical rate of speed increase. A realistic target for silicon-on-insulator (SOI) delay and power reductions in comparison to bulk technology are 40% and 30%, independent of scaling, mostly through capacitance reduction. Denser isolation allows more compact layout and easy integration of different high speed (E/D NMOS), low power (CMOS), analog (bipolar, grounded-body CMOS) and memory devices. Silicon device speed record (13 ps at 1.5 V, 300 K) has been set with SOI E/D NMOS. Leakage current due to steady state and transient floating-body induced threshold lowering (FITL) is a device issue which deserves more attention.
Theory of Scanning Tunneling Microscopy and Scanning Tunneling Spectroscopy Based on the Resonant Tunneling Model: Can We Observe Surface States?
Authors: Kenji Makoshi Kenji Makoshi
Published: October 2002

A theory based on a simple model for resonant tunneling processes is presented to calculate the current in the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). A simple expression of the current is given, which consists of three parts: one for the electron occupation, one for the change of the electronic states by admixtures between the tip and the sample, and the third for current from the surface to the electrode attached to the sample. It is shown that the surface states do not contribute to the tunneling current if they lie in the gap of the bulk band, because we can construct only evanescent waves in such an energy range. However when the surface states appear in a gap at certain wave vectors parallel to the surface but energetically degenerate to bulk states with different parallel wave vectors, they can be observed because the translational symmetry parallel to the surface is broken by the tip. The present theory can be applied to the detailed analysis of the tunneling current combined with suitable electronic state calculations.
√ 3×√ 3 Reconstructions of Si(111) and Ge(111) Induced by Ag and Au
Authors: Nogami Jun , Kejia Wan Kejia Wan , Jon C. Glueckstein Jon C. Glueckstein
Published: October 2002

Both Ag and Au induce reconstructions of the Si(111) and Ge(111) surfaces with √ 3×√ 3R30° periodicity. The structure of the surface for the different noble metal/substrate combinations varies. This paper discusses scanning tunneling microscope results and their relationship to the current understanding of the surface atomic structure in each system.
Molecular Arrangement at Cleaved Single-Crystal Surface of Steraric Acid Observed by Atomic Force Microscope
Authors: Fujii Masatoshi , Fujihara Yasuhiro , Sugisawa Satoshi , Fukada Kazuhiro , Tadashi Kato Tadashi Kato , Tsutomu Seimiya Tsutomu Seimiya
Published: October 2002

The cleaved surface of a B-form single crystal of stearic acid was observed with an atomic force microscope (AFM) under the magnification of molecular resolution. The AFM image obtained shows a regular array of circular spots which are reasonably regarded to be the end methyl group of the alkyl chain of stearic acid. The AFM images observed were subjected to a Fourier analysis from which exact two-dimensional lattice spacing was estimated. The molecular packing of the methyl groups at the cleaved surface seems to differ slightly from that in the bulk (001) plane, and suggests that structural reformation occurs when the crystal is cleaved.
High Resolution of Magnetic Force Microscope Image using a Just-on-Surface Magnetic Force Microscope
Authors: Hosaka Sumio , Honda Atsushi Kikukawa
Published: October 2002

The high spatial resolution of a magnetic force microscope (MFM) has been studied with respect to a tip-sample separation, theoretically and experimentally. In the estimations, the MFM resolution becomes high as the separation decreases. The separation of less than 1 nm provides an advanced resolution of less than 10 nm. In the experiments, the probe of the conventional MFM cannot be allowed to come within 10∼20 nm of the sample to avoid mixing the atomic force with the magnetic force. By contrast, just-on-surface-MFM (JS-MFM), which allows for the MFM measurement at a small separation within 1 nm, can provide a detailed observation of the localized surface magnetic stray field with an advanced resolution of less than 10 nm.
Time Evolution of Contact-Electrified Electron Dissipation on Silicon Oxide Surface Investigated Using Noncontact Atomic Force Microscope
Authors: Fukano Yoshinobu , Uchihashi Takayuki , Okusako Takahiro , Chayahara Ayumi , Sugawara Yasuhiro , Yamanishi Yoshiki , Oasa Takahiko , Seizo Morita Seizo Morita
Published: October 2002

Deposition and observation of contact-electrified electrons on thin silicon oxide surface were performed separately and successfully investigated by the noncontact DC mode measurement of the induced electrostatic force with an atomic force microscope (AFM). It was found that the dissipation of the contact-electrified electrons had three stages with respect to time, which correspond to a stable state, an unstable state and a trapped state at the charge trap site.
New Large Angle Tilt Implanted Drain Structure: Surface Counter-Doped-Lightly Doped Drain for High Hot Carrier Reliability
Authors: Chou Jih Wen , Chang Chun Yun , Huang Chimoon , Ho Lien Tse , Ko Joe , Hsue Peter
Published: October 2002

A new surface counterdoped-lightly doped drain (SCD-LDD) structure with large angle tilt (LAT) implantation is proposed in this study. This structure introduces an additional larger tilt angle and lower-energy BF2 implant after the n- implant, which counterdopes the n- surface concentration to achieve a gate/ n- fully overlapped, buried and sloped n- region inside the gate edge. As a result, the lateral electric fields inside the gate edge are reduced and pushed deeper into the substrate. In addition to a reduction in substrate current, this profile also suppresses hot carrier injection by driving the current away from the surface and the maximum electric field; then it shifts the avalanche region further into the bulk Si. This consequently produces a more effective enhancement of hot carrier reliability than that of conventional LDD's and controlled large-angle-tilt implanted drains (LATID's) for submicron VLSI circuits under 5 V operation. In conclusion, this SCD-LDD provides one more degree of freedom in optimizing the n- region doping profiles as a new LATID structure.
Stable Passivation Systems for GaAs Prepared by Room-Temperature Deposition of SiO2 Films
Authors: Hashizume Tamotsu , Yoshino Masaki , Ishikawa Motohiro , Shimozuma Mitsuo
Published: October 2002

The 50-Hz plasma enhanced chemical vapor deposition technique allowed the deposition of high-quality SiO2 onto GaAs at room temperature without destroying the surface structure of amorphous-As covered GaAs, resulting in the stable SiO2/As/GaAs passivation system. Abrupt carrier profiles were reproducibly obtained for the Si-implanted and rapid thermal annealed GaAs using this passivation system.
Flux Pinning of the Stress Field in Y1-xLnxBa2Cu3O7-δ
Authors: Fang Minghu Fang Minghu , Cai Meng Cai Meng , Jiao Zhengkuan Jiao Zhengkuan , Zhang Qirui Zhang Qirui
Published: October 2002

Our experimental results of flux pinning effects in Y1-
x

Ln

x

Ba2Cu3O7-δ(Ln=Gd, Sm and Eu) samples show that for each partially substituted sample, there exists strong flux pinning at higher field in comparison with the undoped samples, and the maximum pinning force density F

m
a
x

p
increases with the increasing of the atomic radius of Ln. Furthermore, the F

m
a
x

p
(x) vs x curve is symmetrical with respect to x=0.5 in Y1-
x

Eu

x

Ba2Cu3O7-δ. It is suggested that there are two different flux pinning mechanisms in these samples. The pinning effect at higher field may stem from the lattice stress field due to the partial substitution of Ln with different atomic radii for Y. The pinning effect at lower field is caused by the magnetic interaction between a vortex and the grain surfaces.
Copying Characteristics of the Magnetically Induced Superresolution Disk
Authors: Takahashi Koyata , Toshio Inase Toshio Inase , Akio Kondo Akio Kondo
Published: October 2002

Copying characteristics of recorded domains from the recording layer to the readout layer were studied for the magnetically induced superresolution disk. It was found that the larger the difference of the wall energy between the switching layer and the readout layer was, the better copying characteristics were. The copying field of a domain tended to be much less than that without or outside of a domain. To explain this behavior, it was proposed that the interface wall within a domain sinks into the recording layer in comparison with the one without or outside of a domain.