bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
Effect of Dilution Gases on the SiH3Radical Density in an RF SiH4Plasma
Authors: Hideshi Nomura Hideshi Nomura , Akihiro Kono Akihiro Kono , Toshio Goto Toshio Goto 
Published: October 2002

Infrared diode laser absorption spectroscopy was used to measure the density of silyl ( SiH3) radicals in low-pressure (4.0 Pa) 13.56-MHz rf plasmas utilizing H2/, He/, Ar/, and Xe/SiH4gas mixtures. The SiH3production frequency per SiH4molecule was also derived from the SiH3density and its decay rate in the afterglow. The observed SiH3density decreased with increasing dilution ratio in all the gas mixtures, but the SiH3production frequency per SiH4molecule increased significantly for Xe dilution and remained nearly constant for H2, He, and Ar dilution. Based on these results, the relative importance of different SiH3production channels is discussed.
Experimental Study of Very-High-Frequency Plasmas in H2by Spatiotemporally Resolved Optical Emission Spectroscopy
Authors: Shigeru Kakuta Shigeru Kakuta , Takeshi Kitajima Takeshi Kitajima , Yutaka Okabe and Toshiaki Makabe Yutaka Okabe and Toshiaki Makabe 
Published: October 2002

A very-high-frequency (VHF) plasma at 100 MHz is experimentally investigated in parallel-plate configuration in H2using spatiotemporal optical emission spectroscopy and current-voltage-power waveforms. The observed optical emission intensity and net excitation rate profiles have strong temporal and spatial variations. The VHF plasma is still capacitive, and is maintained by reflected electrons in the oscillating sheath next to the instantaneous cathode. The characteristics of VHF plasmas, that the excitation rate increases in proportion to the square of driving frequency, and that the minimum sustaining voltage and pressure decrease with increasing frequency, are experimentally confirmed at pressures, ranging from 0.01 to 2 Torr and at the frequency of 100 MHz .
Laser-Induced Fluorescence Observation of In-Atoms Produced by DC Reactive Sputtering of Indium-Tin-Oxide Target
Authors: Yoshinobu Matsuda Yoshinobu Matsuda , Takuya Kido Takuya Kido , Kazumi Ano Kazumi Ano , Kazuhiro Shirakata Kazuhiro Shirakata , Hiroshi Fujiyama Hiroshi Fujiyama 
Published: October 2002

Spatial density profiles of sputtered In-atoms in a dc glow discharge with an indium-tin-oxide (ITO) cathode were measured by laser-induced fluorescence (LIF) spectroscopy. The absolute density of In-atoms was obtained by calibrating the LIF signal with the Rayleigh scattering signal for Ar. The spatial density profile of In-atoms had a peak at a certain distance from the cathode, and this peak density was about 1011 cm-3 for pure Ar dc discharge at 0.2 Torr and 0.6 Wcm-2. The behavior of spatial profiles of the absolute In-density was investigated as a function of dc discharge power, total pressure ( Ar+O2), and O2 partial pressure. Addition of a small amount of O2 caused a drastic change in both the absolute In-density and its spatial distribution. From these observations, the reactive sputtering mechanism in a dc glow discharge is discussed.
Electrode Lifetimes in a Plasma Focus Soft X-Ray Source
Authors: Yasuo Kato Yasuo Kato 
Published: October 2002

The lifetime of electrodes and the insulator in a plasma focus device is investigated for application to short-wavelength radiation sources. Evaporation and sputtering of electrodes are the root of almost all problems when a plasma X-ray source is applied to lithography. The erosion of electrodes is reduced by the combination of polarity inversion of the applied voltage to the electrodes, application of tungsten-inserted hollow electrode to the inner electrode, and improvements in the shape of the outer and inner electrodes. Weight of the debris is reduced from 38 µg/shot to 9 µ g/shot at 3.5 kJ energy discharge upon introducing these improvements. After 400,000 discharges, electrode lifetimes are estimated at more than 1 million discharges, and the ceramic insulator maintains a high discharge repetition rate. The X-ray intensity increases as the copper vapor is reduced in the pinched plasma.
Electron Spin Resonance-Computer Tomography with Field Gradient Wires inside the Cavity: Images of Alanine Dosimeters and Some Materials
Authors: Masahiro Yamamoto Masahiro Yamamoto , Motoji Ikeya Motoji Ikeya 
Published: October 2002

A large magnetic field gradient with high linearity was obtained for electron spin resonance (ESR) imaging using sixteen straight wires inserted into a cylindrical microwave cavity of TE011mode. Pentacrinus, a carbonate fossil and commercial alanine dosimeters irradiated by 30 kGy have been imaged with the magnetic field gradient intensity of 1 T/m or 2 T/m to determine the resolution of the ESR-computer tomography (CT) imaging. The distribution of radicals in a γ- and an X-irradiated alanine dosimeter has been imaged to investigate the uniformity of an alanine pellet with polystyrene and the self-attenuation effect. A piece of burned wood has been imaged to visualize the oxidation reaction.
Metal-Insulator-Metal Tunneling Light-Emission Junction in Surface Acoustic Wave Field
Authors: Min Cai Yi , Sun Cheng Xiu Sun Cheng Xiu , Gao Zhong Lin Gao Zhong Lin 
Published: October 2002

In the study of metal-insulator-metal (MIM) light-emitting tunneling junctions (LETJs), we adopt surface acoustic waves (SAW) in order to induce light emission instead of surface roughness and set our MIM LETJs in the field of SAW. As a result, the LETJs' efficiency and stability have been increased appreciably.
In this paper, we introduce the LETJs' basic structure and technology, and discuss its emission spectrum and I-V characteristic curve. Above all, we observe the negative resistance phenomenon (NRP) in its I-V curve.
Trains of Flux Jumps Observed in a Quench-and-Melt-Grown YBa2Cu3O7 under Pulsed Magnetic Field
Authors: Itoh Takeo Takizawa , Tanimura Yoshinobu , Kohji Kanbara Kohji Kanbara , Mitsuru Morita Mitsuru Morita , Misao Hashimoto Misao Hashimoto 
Published: October 2002

The motion of quantized fluxes in ring-shaped YBa2Cu3O7 samples has been observed under pulsed magnetic field in the 15 K to critical temperature (T
c) range. Successive flux jumps have been observed in a low-J
c sample, where J
c is the transport critical current density. All these jumps are determined by the Lorentz force, and not by the thermal avalanche conditions. It is suggested that the trains of jumps are caused by the weakened pinning force in a degraded sample.
Electrical Properties of Layered ZrSe2Single Crystals Annealed in Selenium Atmosphere
Authors: Tetsuo Ikari Tetsuo Ikari , Kouji Maeda Kouji Maeda , Koji Futagami Koji Futagami , Akio Nakashima Akio Nakashima 
Published: October 2002

Temperature dependencies of electron carrier concentrationnand Hall mobility µHof layer ZrSe2single crystals are investigated for samples annealed in vacuum or Se atmosphere. The high carrier concentration in the order of 1019 cm-3for the as-grown sample decreases to 1018 cm-3upon annealing in Se atmosphere. We consider that the dominant donor state in ZrSe2is produced by a complex involving interstitial Zr atoms and Se vacancies. The temperature dependence of µHis explained by inter and intravalley electron scattering by acoustic phonons.
Nanometer Modifications of Non-Conductive Materials Using Resist-Films by Atomic Force Microscopy
Authors: Shin-ichi Yamamoto Shin-ichi Yamamoto , Hirofumi Yamada Hirofumi Yamada , Hiroshi Tokumoto Hiroshi Tokumoto 
Published: October 2002

We demonstrate the nanolithography of a SiO2 substrate by modification of ultrathin films of nonconducting polymer using an atomic force microscope (AFM) followed by wet etching. Using an AFM tip under high normal forces of the order of 100 nN in air, and at a writing speed of 1 µm/s, large areas of 10 ×10 µm2 patterns with widths less than 28 nm and depths of 10 nm were reliably fabricated onto the SiO2 substrate.
Atomic Layer Etching of Silicon by Thermal Desorption Method
Authors: Shigeru Imai Shigeru Imai , Takeo Haga Takeo Haga , Osamu Matsuzaki Osamu Matsuzaki , Takeo Hattori Takeo Hattori , Masakiyo Matsumura Masakiyo Matsumura 
Published: October 2002

Atomic layer etching of Si has been realized by modulating the substrate temperature synchronized with chlorine gas irradiation. This is based on the surface chemistry wherein chlorine atoms adsorbed on the clean Si surface at room temperature are thermally desorbed as SiCl2 over 650°C. For Si(111) substrates, the etching rate R was saturated at about 3/7 monolayer per cycle for the peak temperature of more than 675°C. The saturated etching rate corresponds to half the number of rest atoms of the Si(111) 7 ×7 surface. The chlorine dosage for the saturation was about 3.5 mTorr × 4 s. The experimental results agreed well with the theoretical estimations based on the desorption kinetics of SiCl2. The increase of the surface roughness by etching was less than one monolayer.
Dielectric Properties of Pb(ZrxTi 1-x)O 3 Single Crystals Including Monoclinic Zirconia
Authors: Tatsuya Hatanaka Tatsuya Hatanaka , Hideo Hasegawa Hideo Hasegawa 
Published: October 2002

Pb(ZrxTi1-x
)O3 single crystals including monoclinic zirconia were grown from Pb(Zr0.5Ti0.5)O3 ceramics in a PbO-KF-PbCl2 flux. The composition of the crystals was determined as Pb(Zr0.3Ti0.7)O3 and the crystals included 8 vol% zirconia particles with a size of ∼5 µm. The dielectric constants showed a maximun around 415°C although the expected phase transition point (T
c) is about 440°C. The shift of T
c was discussed in terms of the phenomenological Landau theory and explained by the existence of the internal compressive stress caused by the volume expansion of ZrO2.
Atomic-Layer Chemical-Vapor-Deposition of SiO 2 by Cyclic Exposures of CH 3OSi(NCO) 3 and H 2O 2
Authors: Shunsuke Morishita Shunsuke Morishita , Yasutaka Uchida Yasutaka Uchida , Masakiyo Matsumura Masakiyo Matsumura 
Published: October 2002

Atomic-layer chemical-vapor-deposition (AL-CVD) of SiO2 has been achieved by cyclic exposures of CH3OSi(NCO)3 and H2O2 at room temperature. The deposition rate was saturated at about 2.0 Å/cycle i.e., equal to the ideal quasi-monolayer/cycle. The surface roughness after 100 deposition cycles was found to be less than ±10 Å by atomic force microscopy (AFM). Film properties were also evaluated by auger electron spectroscopy (AES), X-ray photoemission spectroscopy (XPS), and Fourier transform IR (FT-IR) spectroscopy.
Effect of Intense Intersubband Optical Excitation on the Electron Distribution in GaAs/AlAs Quantum Wells
Authors: Soichiro Tsujino Soichiro Tsujino , Hidefumi Akiyama Hidefumi Akiyama , Hiroharu Sugawara Hiroharu Sugawara , Mathilde Rüfenacht Mathilde Rüfenacht , Yutaka Kadoya Yutaka Kadoya , Takeshi Noda Takeshi Noda , Hiroyuki Sakaki Hiroyuki Sakaki 
Published: October 2002

Hot electrons were generated in n-doped GaAs/AlAs multiple quantum wells by optical intersubband excitation and their energy distributions were studied at 10 K. By measuring photoluminescence (PL) spectra, the hot-electron temperatureTelwas quantitatively evaluated, taking into account such effects as the degenerate distribution of electrons, impurity-induced level broadening, and the distribution of holes. It was found that, when the intensityPof the excitation was 30 kW cm-2, i.e. a few percent of the onset intensity for absorption saturation,Telincreased from 10 K to 120 K while the lattice temperature remained unchanged. WhenPwas between 10 W cm-2and 30 kW cm-2, the rise ofTelwas well explained by the balance between the photon energy absorption and the energy loss due to the LO phonon emission inside the ground subband.
Maskless Deposition of Au on GaAs by Low-Energy Focused Ion Beam
Authors: Kito Kuniyoshi , Yanagisawa Junichi , Monden Kentaro , Nakayama Hiromasa , Yuba Yoshihiko , Gamo Kenji 
Published: October 2002

Direct deposition of Au films on GaAs substrate was performed using low-energy focused ion beam (FIB) irradiation. Pure Au film was obtained and current-voltage (I–V) characteristics of the Au/GaAs contacts were measured. The degradation of I–V characteristics compared to those of Au/GaAs contacts formed by evaporated Au was observed even for deposition at an energy of 50 eV due to ion-irradiation-induced damage. The I–V characteristics were somewhat improved by annealing at 200°C for 1 min. As an example of application, a Au gate was formed on a GaAs/AlGaAs heterostructure using low-energy FIB direct deposition, and current control capability was demonstrated.
Turn-off Transient Analysis of a Double Diffused Metal-Oxide-Semiconductor Device Considering Quasi Saturation
Authors: Chung-Min Liu Chung-Min Liu , James B. Kuo James B. Kuo 
Published: October 2002

This paper reports the turn-off transient of a double diffused metal-oxide-semiconductor (DMOS) device considering the quasi-saturation behavior. Based on the two-dimensional (2D) simulation result, during the input ramp-down period of 100 ps, the accumulated electrons below the gate oxide are pushed toward the p region below the lateral channel toward the source, causing a surge in source current. After the input ramp-down period, these electrons are withdrawn from the drain by the quasi-saturation current.
Estimation of the Emission Barrier Height of p-Type Semiconducting Diamond from its Field Emission Property
Authors: Ken Okano Ken Okano , Satoshi Koizumi Satoshi Koizumi , Junji Itoh Junji Itoh 
Published: October 2002

The emission barrier height of p-type semiconducting diamond has been estimated relatively by comparing the field emission property of a diamond field emitter array (FEA) and a molybdenum (Mo) FEA having the same geometry. Diamond FEA showed lower turn-on voltage than Mo FEA in the emission current-anode voltage characteristics. The slope ratio of diamond FEA to Mo FEA in Fowler-Nordheim (F-N) plots yielded the emission barrier height ratio of the diamond to Mo as 0.44 ±0.06. From the obtained ratio, the emission barrier height of the diamond can be estimated to be 1.87 ±0.26 eV when the work function of Mo (4.24 eV) is assumed.
Preferentially (105)-Oriented SrBi2Ta2O9 Films Prepared by Laser Ablation Method
Authors: Yoshihiro Oishi Yoshihiro Oishi , Wenbiao Wu Wenbiao Wu , Keigo Fumoto Keigo Fumoto , Masanori Okuyama Masanori Okuyama , Yoshihiro Hamakawa Yoshihiro Hamakawa 
Published: October 2002

SrBi2Ta2O9 thin films are prepared on both Pt sheet and Si wafer by the laser ablation method using an ArF excimer laser below 500°C. Crystallographic properties of the film are characterized with substrate temperature (T
s) and O2 gas pressure as parameters. SrBi2Ta2O9 thin films are oriented preferentially to (105) on both Pt sheet and Si wafer. X-ray photoelectron spectra (XPS) depth profile reveals a homogeneous composition and XPS signals of Bi suggest oxygen deficiency of the film on the Si wafer. The films deposited on Pt and Si consist of spherical grains of about 250 and 200 nm diameter, respectively. A good capacitance-voltage (C–V) hysteresis curve is obtained in the metal oxide semiconductor (MOS) structure of the SrBi2Ta2O9 film on SiO2/Si at T
s of 500°C.
Diffusivities and Activities of S Implanted into GaAs through an As-doped a-Si:H Film
Authors: Masanori Sakaguchi Masanori Sakaguchi , Katsuhiro Yokota Katsuhiro Yokota , Akira Shiomi Akira Shiomi , Haruya Mori Haruya Mori , Akiyoshi Chayahara Akiyoshi Chayahara , Yoshie Fujii Yoshie Fujii , Kiyohito Hirai Kiyohito Hirai , Hiromichi Takano Hiromichi Takano , Masao Kumagai Masao Kumagai 
Published: October 2002

Sulfur (S) ions are implanted at 500 keV into GaAs through 120 nm a-Si:H films doped with arsenic atoms at a concentration of 2×1020 cm-3. The samples are annealed in Ar gas at temperatures of 700–1000°C for 15 min. The sheet carrier concentration increases with increasing implant dose and annealing temperature. The diffusivity of the S atoms decreases with increasing implant dose. Silicon (Si) atoms are also doped from the a-Si:H films into GaAs during annealing and S+ implantation. The distribution of the Si atoms becomes slightly shallower as the implant dose increases. The carrier concentrations, however, are left unchanged by Si doping.
Structural Study of Amorphous SiNx:H Films Produced by Plasma-Enhanced Chemical Vapor Deposition
Authors: Kazuki Wakita Kazuki Wakita , Hideki Hayashi Hideki Hayashi , Yoshikazu Nakayama Yoshikazu Nakayama 
Published: October 2002

The structure of amorphous SiNx:H films prepared by glow discharge decomposition of SiH4 and NH3 has been investigated by measurements of X-ray diffraction intensity. The first peak in atomic density function obtained by analysis of diffraction intensity indicates a nearest-neighbor distance of 1.74 Å which corresponds to the Si–N bond length of 1.730–1.745 Å in β-Si3N4 crystal. We have also estimated the Si–N–Si–N bond configuration by comparing the corrected observed scattering intensity with the scattering intensity calculated using a simple bonding model. It has been shown that a Si atom bonded to a N atom with a coplanar bond has two tetrahedral bonds in the plane of the coplanar bonds.
Characterization and Fabrication of Chimney-Shaped Metal Field Emitters
Authors: Cheng Huang-Chung , Wang Chih-Chong , Hsieh Tzu-Kun Ku 
Published: October 2002

A novel fabrication technology has been successfully developed for chimney-shaped metal field emitters in order to improve the electrical characteristics of field-emission devices. This technology is based on anisotropic dry etching and sputtering deposition of metal film as well as wet etching of the attached silicon. It enables easy fabrication of chimney-shaped field emitters with excellent uniformity and high reproducibility. The anode current of the chimney-shaped Cr field emitter array (FEA) is 36.3 µA at the applied voltage of 1100 V and the threshold voltageVT, defined as that for which the anode currentIareaches 1 µA is 787 V. The chimney-shaped Cr FEA emits a current thirty times higher than that from the cone-shaped Cr-clad FEA at the applied voltage of 1100 V. This can be attributed to the presence of many sharp tips along the edge of the chimney-shaped emitter. The degradation phenomenon is not observed because compensation occurs between these many sharp tips. Another merit of this technique is that only one photolithography mask is needed during processing.
Dilution-Gas Effect on Electron Density and Temperature in RF SiH 4 Plasma Based on Microwave Cavity Resonance Measurement
Authors: Hideshi Nomura Hideshi Nomura , Akihiro Kono Akihiro Kono , Toshio Goto Toshio Goto 
Published: October 2002

Using a microwave cavity resonance technique, the electron density (n
e) in a low-pressure (40–100 mTorr) RF (13.56 MHz) SiH4 plasma and the electron loss rate in the afterglow were measured with varying SiH4 fractions in the SiH4/Xe, /Ar, /He and /H2 mixture gases. The behavior of electron temperature (T
e) was estimated from the relative variations of the excitation rate constants (k
em) for emissive rare-gas excited states, which were derived by combining the results of electron density measurements with optical emission measurements. The product k
em
n
e generally increased with increasing dilution but the behaviors of the individual k
em and n
e differ considerably for different mixture gases. The results were discussed in terms of energy and particle balance consideration. It was found that the dominant electron loss process in the afterglow is attachment and that the major attaching species is not SiH
x
(x=0–4) but some larger molecules produced in the plasma, even under the low-power (< about 5 W) conditions studied. The same attachment process was shown to have a significant role in determining T
e and n
e in the active plasma.
Si Dimer Chain on Si(100)-2×1:H Surface Fabricated by Scanning Tunneling Microscope
Authors: Huang Dehuan , Yamamoto Yoshihisa 
Published: October 2002

In order to fabricate an atomic chain with metal, semiconductor and insulator phases on an atomically flat insulating surface by manipulating single atoms one by one with an ultrahigh-vacuum scanning tunneling microscope (UHV STM), we investigated the Si(100)-2×1 surface and its hydrogen termination. The obtained STM images show that the Si(100)-2×1 surface will have fewer defects when appropriate preparation is employed. We successfully prepared the monohydride Si(100)-2×1:H surface using the dry etching process. Hydrogen atoms on the Si(100)-2×1:H surface can be extracted by applying both positive and negative voltage pulses between the STM tip and the sample surface with a certain tunneling current. This implies that the mechanism for extracting hydrogen atoms on the monohydride surface is due to not only electron excitation but also field evaporation. There is a pairing effect to force extracted hydrogen atoms in pairs from dimers. Using this technique, we fabricated a Si dimer chain on the Si(100)-2×1:H surface by removing pairs of hydrogen atoms.
A Study of Damage Induced in In0.52Al0.48As Surface by Reactive Ion Etching
Authors: Gwo-Cherng Jiang Gwo-Cherng Jiang 
Published: October 2002

Photoreflectance (PR), Raman scatter (RS), and photoluminescence (PL) experiments have been carried out to characterize the In0.52Al0.48As surface exposed to plasma with a gas of methane-hydrogen. PR spectra indicate that reactive ion etching (RIE) causes damage such as nonradiative recombination centers, scattering centers, and defects leading to the decrease of signal intensity, broaden linewidth and red shift of the transitions by increasing the rf power. In the Raman scattering study, RIE causes damage against InAs-like and AlAs-like longitudinal optic (LO) modes vibration. As the rf power increased, the maximum of two LO modes shifts towards lower frequency and the line shape becomes increasingly asymmetric. Also, the degraded intensity causes by disorder and point defects gradually with increasing rf power. Corresponding PL measurements showed that the transition energies red-shift with increasing the rf power. In addition, the spectral feature a broadens, and the intensity decreases with rf power more than 200 W. There is a good correlation of the PL, PR, and RS indicating that these methods can be used as sensitive evaluate for near surface damage of the epilayer.