bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Characteristics of an Electron Beam Pumped XeF(C→A) Laser with Positive Branch Injection-Controlled Unstable Resonators
Authors: Yamaguchi Shigeru , Hofmann Thomas , Dane C. Brent , Wilson William L. , Yehuda Nachshon Yehuda Nachshon , Frank K. Tittel Frank K. Tittel
Published: February 2005

The performance of injection controlled on-axis (centrally obstructed) and off-axis (non centrally obstructed) unstable resonators with magnifications between 2 and 3 for an electron beam pumped high power XeF(C→A) excimer laser system has been evaluated both in the near and far field. The angular beam divergence with the tested resonators was typically 2-3 times that of a diffraction-limited beam. A beam divergence angle as low as 128 µrad was obtained with a circular cross-section on-axis unstable resonator geometry of magnification 3. A peak brightness of 3×1014 W/(sr·cm2) with a beam divergence of 160 µrad was measured for a square cross-section off-axis resonator of magnification 2. In comparison with an on-axis resonator of the same magnification, the experimental results demonstrated that an off-axis unstable resonator offers an effective configuration for improving the laser beam quality without decreasing the output energy of an injection controlled XeF(C→A) excimer laser.
Effects of Insulating Layers and Active Layer on ZnS:Tb, F Thin-Film Electroluminescent Devices
Authors: Hsu Chin Tsar , Lin Ying Jen , Yan Kuin Su Yan Kuin Su , Meiso Yokoyama Meiso Yokoyama
Published: February 2005

This paper describes the effects of insulating layers and active layer on the ZnS:Tb,F thin-film electroluminescent (TFEL) devices. A green-colored device, deposited by the RF-magnetron system, having doubly-stacked insulating layers has been developed to elucidate the role of insulators. It is shown that the semi-insulating layer, HfO2 film, deposited adjacent to an active layer acts as a carrier injector due to Poole-Frenkle emission, while the insulating SiO2 films act as a carrier limiter. In addition, improvement on device performance, such as crystalline quality of the ZnS:Tb,F thin film and the relative amount of fluorine to terbium, F/Tb, is also discussed.
Theoretical Analysis of Bound-to-Continuum State Infrared Absorption in GaAs/AlxGa1-xAs Quantum Well Structures
Authors: Rusli Rusli , Tow Chong Chong Tow Chong Chong , Soo Jin Chua Soo Jin Chua
Published: February 2005

This paper presents the first detailed analysis of bound-to-continuum state infrared optical transitions in doped GaAs/Al
x
Ga1-x
As quantum well structures taking into account the energy-dependent intrasubband relaxation time. Effects of the quantum well structural parameters on the absorption coefficient are studied so as to provide a basic understanding of how optimal device performance can be achieved by the proper choice of parameters. Theoretical calculations show that absorption peak wavelength and bandwidth are strongly dependent on the well width and barrier height, in agreement with reported experimental results. Therefore, with variation in the structural parameters, the absorption bandwidth can be tuned over a large range.
Pyroelectric Properties of Lead Antimony Stannate-Lead Titanate-Lead Zirconate Ceramics Modified with La and Mn
Authors: Lee Sung Gap , Park Young Hie Lee
Published: February 2005

In the present study, 0.10Pb(Sb1/2Sn1/2)O3-0.25PbTiO3-0.65PbZrO3 ceramics modified with La2O3 (1 mol%) and MnO2 (0∼0.30 mol%) were fabricated, and the structural and pyroelectric properties with different amounts of MnO2 were studied. The crystal structure of specimens was rhombohedral, and average grain sizes decreased with increasing amounts of MnO2. The (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3 specimen modified with 0.24 mol% MnO2 showed a large pyroelectric coefficient, p, (=6.73×10-8 C/cm2 K) and voltage responsivity, R
v, (=125 V/W). Also, in the same specimens, noise equivalent power, NEP, and detectivity, D
*, were 2.376×10-7 W/Hz1/2 and 6.793×106 cm Hz1/2 W, respectively. In the (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3 specimens modified with 0.24 mol% MnO2 voltage responsivity decreased with increasing chopper frequency, and was independent of the thickness of the specimens.
Lead Borate Glass-A New Sintering Agent for BaTiO3 Ceramics
Authors: Chunz-Heuy Wang Chunz-Heuy Wang , Long Wu Long Wu
Published: February 2005

Sintering of BaTiO3 with 4PbO·B2O3 was studied with soak temperature ranging from 1150°C-1400°C and dwell time for 4 h. The PbO-based glasses which exist high polarizability were helpful to the dielectric and piezoelectric properties of the system. The eutectic temperature of the 4PbO·B2O3 was around 500°C, so it would provide liquid phase during the firing process. The glass frit has more significant effect on densification, grain size, and grain size distribution in the system. From SEM observation, the 4PbO·B2O3 appears to be a densification promotor during sintering for BaTiO3 ceramics. The dielectric and pieso-electric properties will also be investigated in this system.
Computer Simulation of Film Growth Process on the Two-Dimensional Penrose Pattern
Authors: Sasajima Yasushi , Tanaka Hideki , Ichimura Minoru , Itaba Masanori , Ozawa Satoru
Published: February 2005

We performed computer simulation of the film growth process on the two-dimensional (2D) Penrose pattern, which is considered a typical structural model of quasicrystal. The atomistic structure of the deposited atoms was calculated as a function of time under various conditions of atomic binding energy, temperature and deposition rate. The Monte Carlo method based upon the solid-on-solid model was utilized for the present calculation. We found a geometrical restriction on the growth front of grains in the 2D Penrose pattern, which is also expected for the growth of an actual quasicrystal.
Growth of GaAs Epitaxial Microcrystals on an S-Terminated GaAs Substrate by Successive Irradiation of Ga and As Molecular Beams
Authors: Nobuyuki Koguchi Nobuyuki Koguchi , Keiko Ishige Keiko Ishige
Published: February 2005

Numerous GaAs epitaxial microcrystals with an average base size of 250 Å×430 Å with (111) facets were fabricated on a sulfur-terminated (S-terminated) GaAs (001) substrate with successive irradiation of Ga and As molecular beams. The growth of GaAs microcrystals on the S-terminated substrate was caused by a vapor-liquid-solid (VLS) mechanism. This phenomenon originated in the inertness for the adhesion of Ga and As molecules and nearly equal lattice constants of the S-terminated GaAs surface and GaAs surface. This method, called droplet epitaxy, is thought to show promise as a growth method for fabricating GaAs quantum well boxes.
Scanning Auger Microscopy Study of Heterogeneous Growth of SiC Film on Si(100) by Reaction with a C2H2 Beam
Authors: Isao Kusunoki Isao Kusunoki
Published: February 2005

A Si(100) surface which was reacted with a well-collimated C2H2 beam was studied using scanning Auger electron microscopy (SAM) after storage in air for a long period of time. Formation of a SiC film was confirmed by the chemical shifts of the C KLL, Si LVV, and Si KLL peaks in the AES integral mode. Chemical maps of the surface were obtained using SAM. A sharp boundary of the region of SiC formed by the C2H2 beam irradiation was observed. The grains with bright tones in the SEM image observed at high magnification were identified as SiC crystals using SAM. The dark areas among the grains were the elemental Si regions. It is clear that the SiC film on the Si surface was not uniformly formed on a µm scale. This suggests that the SiC film grows via nuclear growth.
Correlation between Optical Properties and Crystallite Size in Porous Silicon
Authors: Lehmann Volker , Jobst Barbara , Muschik Thomas , Kux Andreas , Petrova-Koch Vesselinka
Published: February 2005

Recently a quantum size effect was proposed to be responsible for the blue shift of optical absorption edge and photoluminescence peak wavelength as well as for the porous silicon (PS) formation itself. In the debate about the mechanism of light emission from PS a correlation between particle size and luminescence peak position would be a key test of the confinement approach. In this letter X-ray diffraction results of as-etched PS samples will be presented that indicate a decrease of particle size and an increase of stress in conjunction with a blueshift of photoluminescence wavelength and absorption edge.
Phenomenological Studies in Laser Cladding. Part II. Thermometrical Experiments on the Melt Pool
Authors: Kizaki Yoshimi , Azuma Hirozumi , Yamazaki Satoshi , Takagi Hisashi Sugimoto
Published: February 2005

A novel two-color pyrometer composed of a high-speed shutter TV camera and an image intensifier is employed to study the surface temperatures of the cladding layer under CO2laser radiation. The two dimensional image of the surface temperature of the melt pool was stored in the frame memory in National Television System Committee (NTSC) formula. Also, high-speed photography was used to observe the dynamic behavior of the melt pool. The rapid motion and temperature change of the melt pool were observed and the former was greater than the laser scan (200 Hz). From these two time-resolved measurements, the laser cladding layer was found to be under the control of the dynamic behavior of the melt pool.
Multiple-Barrier Systems for Phonons: Transmission Characteristics
Authors: Seiji Mizuno Seiji Mizuno , Shin-ichiro Tamura Shin-ichiro Tamura
Published: February 2005

Transmission characteristics of acoustic phonons
in multiple-barrier systems are theoretically studied.
These systems consist of an alternate stacking of bulk layers
and periodic superlattices.
The phonon transmission rates are derived analytically
based on the transfer matrix method.
We consider phonons within a frequency gap
of the superlattices and find the resonant transmission of these phonons.
The systems considered is analogous to the Kronig-Penny potential
structure for electrons.
Elastic Behaviour of Salol during Melting and Solidification Processes
Authors: Hiroaki Kamioka Hiroaki Kamioka
Published: February 2005

The shear wave velocity and the attenuation of ultrasonic waves in salol have been measured using the pulse transmission method in the temperature range from 10 to 80°C through the melting temperature of 42°C. The frequency of the ultrasonic wave was 1 MHz. The shear wave velocity immediately below the melting point was 670 m/s. By combining the present results with our previous data on the compressional wave velocity, an analysis on the variation in elastic properties of salol during its melting and solidification processes was performed.
Time-Dependent Specific Heat in Vitreous Silica Using Diffusivity Measurement
Authors: Hiroshi Ikari Hiroshi Ikari
Published: February 2005

Pulsed diffusivity measurement of vitreous silica with the sample immersed in liquid helium has been performed. The observed short-time diffusivity is in good agreement with the dc diffusivity over the temperature range from 1.5 K to 3.9 K, which is consistent with the earlier diffusivity measurements. Our result at 1.5 K is, however, not consistent with the time-dependent specific heat measurement in an adiabatic sample arrangement. This may be due to the different sample-to-bath time constants. The diffusivity at low temperatures seems to remain an unsolved problem.
Characterization of Polyvinylchloride by Means of Sound Velocity and Longitudinal Modulus Measurements
Authors: Koda Shinobu , Yamashita Kiyoo , Katsuyuki Matsumoto Katsuyuki Matsumoto , Hiroyasu Nomura Hiroyasu Nomura
Published: February 2005

The longitudinal and transverse sound velocities for polyvinylchloride and polycarbonate with different molecular weights were measured at 30°C. The temperature dependence of the longitudinal sound velocity was measured up to 110°C. The longitudinal sound velocity decreased with increasing molecular weight, while the transverse sound velocity was nearly independent of the molecular weight. The longitudinal, shear and bulk moduli were obtained from the sound velocity and density data. Longitudinal and bulk moduli depended on the molecular weight strongly, but the shear modulus, Young's modulus and Poisson's ratio were insensitive to the molecular weight. The longitudinal sound velocity decreased with increasing temperature and the temperature dependence of the velocity changed drastically around the glass transition temperature.
A Theoretical Model of InP Mass Transport
Authors: Hansen Karsten , Peiner Erwin , Guang-Ping Tang Guang-Ping Tang , Andreas Schlachetzki Andreas Schlachetzki
Published: February 2005

A theoretical model of the mass transport observed after heat treatment of InP surfaces is proposed and experimentally verified. In this model the reduction of surface energy obtained by the refilling of concave surface regions at the expense of convex regions is proposed as the driving force for the mass transport. Given the experimental conditions of an InP crystal almost in equilibrium with its vapour in a closed system, the InP growth reaction was found to be the rate-limiting factor for the mass-transport process rather than the supply of phosphorus through the gas phase or indium via surface diffusion.
Ti-Added Al Electrodes on LiTaO3 36° Y-X Substrates for High Power Surface Acoustic Wave Devices I
Authors: Ota Yasuhiro , Hosaka Norio , Yamada Akitsuna Yuhara
Published: February 2005

The influences of the internal stress of the film, annealing treatment and a sputtered Ti-added Al electrode on 36° rotated Y-X LiTaO3 substrates were investigated. Higher activation energy of the time to failure (TF) was obtained when the amount of internal stress was decreased. The annealing temperature is limited to below 400°C because of discoloration and phase change of the substrate. TF with Al-0.6 wt%Ti electrodes in IIDT filters became ten times that obtained with Al-0.2 wt%Ti electrodes. By the increase of the amount of Ti, the grain size and the standard deviation were decreased.
Surface Acoustic Wave Liquid Sensors Based on One-Port Resonator
Authors: Tooru Nomura Tooru Nomura , Tsutomu Yasuda Tsutomu Yasuda
Published: February 2005

A one-port resonator utilizing shear horizontal surface acoustic waves (SH-SAWs) has been used for sensing applications in liquids. SH-SAWs have been excited on a 36°-rotated Y-cut X-propagating LiTaO3 substrate using interdigital transducers and the one-port resonator configuration has been used as a sensing element in liquids. The sensitivity of the resonance frequency and the Q value for the viscosity of liquids have been measured. Experimental results showed that the resonance frequency and the Q value of the SH-SAW resonator varied with the viscosity of the loaded sample liquid.
Measurement of a Specimen with a Discontinuous Elasticity Variation Using Spherical-Planar-Pair Lenses
Authors: Tsukahara Yusuke , Yanaka Masa-aki , Ueha Katsumi Ohira
Published: February 2005

This paper gives a mathematical formula describing an angular spectrum of an ultrasonic wave which is reflected by the flat surface of a solid with a discontinuous variation of elastic constants. Theoretical calculation was compared with experimental observation, and found to show satisfactory agreement. The formula was developed to model the elasticity measurement of functionally gradient materials using spherical-planar-pair lenses.
Dependence of the X-Ray Photoacoustic Signal Intensity of Pure Copper and Brass on Sample Thickness
Authors: Toyoda Taro , Masujima Tsutomu , Shiwaku Hideaki , Ando Masami
Published: February 2005

The hard X-ray photoacoustic signal intensities (I) of pure copper and brass have been measured in the Cu K-edge region as a function of sample thickness (d) (from 5 µm to 100 µm). It is shown that the photoacoustic signal intensities of pure copper and brass decrease above the sample thickness of 10 µm for each modulation frequency. The absolute values of the power law, d(ln I)/d(ln d), of pure copper and brass depend on modulation frequency.
Properties and Mechanism of Si Selective Epitaxial Growth on Al2O3 using Electron Beam Irradiation
Authors: Ishida Makoto , Tomita Takashi , Masahiko Fujita Masahiko Fujita , Tetsuro Nakamura Tetsuro Nakamura
Published: February 2005

Si films were selectively grown on non-electron-beam-irradiated areas of (011̄2) and (0001)α-Al2O3 substrates and (100)γ-Al2O3 on (100)Si structures by Si2H6 gas-source molecular beam epitaxy (MBE) at growth temperatures from 700°C to 900°C. Si layers were not deposited on the areas exposed to an electron beam dose of more than 1.0×1016 electrons/cm2 using an electron-beam graphicsystem. The irradiated surface of Al2O3 substrates was changed from the original surface to an oxygen-reduced surface. Most of the O atoms on the surface were removed at electron dose densities of more than 1×1016 electrons/cm2, which agrees with the critical dose density for selective epitaxy. X-ray photoelectron spectroscopy (XPS) spectra also showed that the surface consisted of metal like Al instead of crystalline Al2O3 after irradiation. The driving force of selective epitaxy can be considered to be the amorphous surface formed by electron irradiation.
Hydrogen Passivation of Polysilicon Thin-Film Transistors by Electron Cyclotron Resonance Plasma
Authors: Baert Kris , Murai Hiroyuki , Kobayashi Kazuhiro , Hirofumi Namizaki Hirofumi Namizaki , Masahiro Nunoshita Masahiro Nunoshita
Published: February 2005

We have investigated the method of hydrogenation of polysilicon thin-film transistors (TFT) by electron cyclotron resonance (ECR) plasma. It is found that with decreasing pressure (1.5 to 0.35 mTorr) of the hydrogen plasma, the substrate temperature rises due to bombardment of hydrogen ions. At the same time, the amount of hydrogen supplied by the ECR plasma increases. Due to these two effects, the passivation proceeds more quickly under low pressure. The amount of hydrogen supplied by a low-pressure ECR hydrogen plasma is higher than that supplied by other means such as Al sintering or rf hydrogen plasma. When polysilicon TFTs are exposed to the ECR hydrogen plasma, the hydrogenation reduces 75% of the electrically active defect states in 15 min. Polysilicon TFTs with an offset-drain structure reached an on/off current ratio of 8 decades after such ECR hydrogen passivation.
Effects of Electron Irradiation on the Local Structural Change in Oriented Bi2Sr2CaCu2Ox Superconductors
Authors: Yoda Teruo Ishibashi
Published: February 2005

Oriented sintered pellets have been irradiated with 3 MeV electrons up to 2×1018/cm2 at 370 K. By means of X-ray line broadening analyses, the crystallite size have been found to be unchanged upon irradiation of 2×1018/cm2. The lattice constants a and b decreased and the periodicity of the structural modulation along the b-axis increased with irradiation. Finally, the intensity of OKLL Auger electrons decreased with irradiation. All the above findings have been explained in terms of oxygen deficiency in the incommensurate modulated structure due to electron irradiation, which results in the deterioration of the superconducting property.
Microstructural Analysis of CoCr Thin Films by Small-Angle Neutron Scattering
Authors: Takei Koji , Suzuki Jun-ichi , Funahashi Yasushi Maeda
Published: February 2005

Small-angle neutron scattering is applied to the analysis of latent microstructures in compositionally separated CoCr thin films. A fine in-grain structure less than 10 nm in size is observed in a film deposited at 200°C using small-angle scattering. This structure coincides with that observed by means of transmission electron microscopy (TEM) in chemically etched thin films. The fine in-grain structure disappears when the deposition temperature is increased to 400°C. This experiment confirms the existence of latent microstructures in CoCr films and reveals that further analysis of magnetic microstructures is possible using neutron scattering.
A Simple Experiment of Simulating Optical Flip-Flop Operator with Two Oscilloscopes and Photodiodes
Authors: Wang Ching-Sheu , Chen Nei-Po , Shy Jow-Tsong , Gou Yih Shun
Published: February 2005

A coupled hybrid optical bistable device composed of two oscilloscopes and two photodiode detectors has been constructed. This device is used to experimentally simulate the basic feature of the flip-flop operator proposed by Otsuka [Opt. Lett. 14 (1989) 72]. Most importantly, it allows us to model the system easily, and hence the condition of an occurrence of the flip-flop operation is accordingly predicted by the linear stability analysis. Furthermore, the influences of symmetry property of the optical system upon the flip-flop operation have been discussed as well.
GaInAsP/InP Low-Mesa CPBH Surface Emitting Laser with an Optimally Deposited MgO/Si Multilayer Laser Mirror
Authors: Baba Toshihiko , Yogo Yukiaki , Suzuki Katsumasa , Kenichi Iga Kenichi Iga , Fumio Koyama Fumio Koyama
Published: February 2005

With an eye to high-temperature cw operation of GaInAsP/InP surface emitting lasers, we have introduced a low-mesa circular planar buried heterostructure for current confinement and a thermally conductive MgO/Si multilayer mirror for heat sinking. The deposition conditions of MgO were optimized to obtain a high mirror reflectivity of over 99%. The lasing operation of a 1.3 µm device loaded with these new materials was demonstrated with a low threshold of 3.5 mA at 77 K under the cw condition.
Deviation Characteristics of Elliptical Laser Gaussian Beams on Optical Head
Authors: Mitsushige Kondo Mitsushige Kondo
Published: February 2005

Direct focusing of laser diode elliptical Gaussian beams on the focused beam profile and on the cross talk and frequency characteristics is described when the beam which enters the objective lens deviates in a direction perpendicular to the information track. The experimentally measured values of the spot profiles agree well with the calculated values. As the result of deviations, the first-order maxima of the focused beam increase and the cross talk level increases. If the acceptable level is 3 dB in the cross talk level, the beam deviation ratio must be less than 0.18 of the objective lens radius. The beam deviation ratio of 0.18 is acceptable for practical applications. The degradation was less than 0.3 dB for frequency characteristics and 0.2 dB for the objective lens transmittance when the beam deviation ratio was 0.18 of the objective lens radius.
Analysis of the Correlative Characteristics between Adjacent Pixels of Amplified Metal Oxide Semiconductor Imager by a New-Type Least Squares Method
Authors: Taketoshi Kazuhisa , Andoh Fumihiko , Imai Katsu Tanaka
Published: February 2005

The magnitude and distribution of spurious response of the pattern of a circular zone plate of the amplified metal oxide semiconductor (MOS) imager are different from those for charge-coupled devices (CCD). When using the trial-and-error or the least squares method, these features could not be explained by any special shape of the sensing aperture or the sensing distribution, but were explained only by the correlation of accumulated charges between adjacent pixels. This correlation causes less spurious resolution and improves the characteristics of the S/N. (1) The shape of the aperture can be shown by a Gaussian distribution in which the standard deviations in the horizontal and vertical directions are 0.266, and 0.231, respectively. (2) The correlative coefficients in the longitudinal, lateral and diagonal directions each stood at 0.0175. The reliability factor R is 0.6%. (3) The measured signal leakage in adjacent pixels by the microoptical spot is 0.02, which fits the calculated value well. (4) The calculated coefficient of noise reduction is 0.65, which agrees with the obtained value of 0.621.
An Optical Temperature Sensor Using Surface Plasmons
Authors: Bruce Chadwick Bruce Chadwick , Michael Gal Michael Gal
Published: February 2005

The principles of an optical temperature sensor, using surface plasmon generation in a material with a large temperature-dependent refractive index, are presented. The sensor design consists of surface plasmon generation in a thin (500 Å) silver film overlaid with hydrogenated amorphous silicon (a-Si:H). A factor of three change in reflected light intensity, from a glass/Ag/a-Si:H interface, is obtained for a 40°C rise in temperature. The device is compatible with fibre optic technology for remote temperature sensing applications.
Raman Scattering of InGaAsP Lattice-Matched to GaAs in the Region of Immiscibility
Authors: Sugiura Touko , Hase Nobuyasu , Goto Hideo , Tanaka Shigeyasu , Hiramatsu Kazumasa , Sawaki Nobuhiko , Akasaki Isamu
Published: February 2005

We have studied the Raman spectra of the In
x
Ga1-x
As
y
P1-y
quaternary alloys lattice-matched to GaAs in the immiscible region. The spectra exhibit four modes of behavior due to four binary compositions: GaP-, InP-, GaAs-, and InAs-like phonon modes. It was found that the phonon spectra in the immiscible region are well explained by the isodisplacement model of Inoshita [J. Appl. Phys. 56 (1984) 2056].
Luminescence from Thermally Oxidized Porous Silicon
Authors: Shiba Kazutoshi , Sakamoto Kunihide , Seiichi Miyazaki Seiichi Miyazaki , Masataka Hirose Masataka Hirose
Published: February 2005

Porous silicon produced by means of anodization in an HF-based solution has been oxidized in an N2+O2 gas mixture at 900 or 1000°C to realize the ideal passivation of a porous Si surface with thermally grown oxide instead of hydrogen termination. Visible photoluminescence at room temperature has been observed for porous Si whose surface is terminated by oxygen. It is shown that the luminescence from the porous silicon is extremely stable under Ar+ laser light (488 nm) irradiation even in air at room temperature. A possible mechanism for the visible light emission is discussed on the basis of the excitation intensity dependence of the luminescence.
Optical and Electrical Properties of p-GaSe Doped with Sb
Authors: Shigetomi Shigeru , Ikari Tetsuo , Nishimura Hideki
Published: February 2005

Measurements of photoluminescence (PL) and Hall effect have been made on Sb-doped p-GaSe. The PL spectra at 77 K are dominated by two new emission bands at 1.75 and 1.66 eV. The 1.66 emission band is enhanced by adding Sb. The temperature dependences of the peak energy and the PL intensity of 1.66 eV emission band reveal that the acceptor level is located at 0.09 eV above the valence band. The deep acceptor level located at 0.57 eV above the valence band is detected by using Hall effect measurements. We found that the deep acceptor level is probably associated with defects or defect complexes formed by Sb atoms in the interlayer.
Study of Oxygen-Deficient Centers in SiO2 Films Using Photoluminescence Spectra
Authors: Awazu Koichi , Watanabe Kikuo , Kawazoe Hiroshi
Published: February 2005

Amorphous silicon dioxide (a-SiO2) films prepared with thermal oxidation of silicon substrates are studied using photoluminescence. Two luminescence bands at 4.2 eV (290 nm) and 2.14 eV (582 nm) are observed in a-SiO2 film. Peak positions of both the photoluminescence and photoluminescence bands are the same as for the B2α band in bulk silica.
Transient and Steady State Carrier Transport under High Field Stresses in SONOS EEPROM Device
Authors: Lin Jyh-Kuang , Chang Chun-Yen , Huang Heng-Sheng , Ho Tai-Shung , Chen Kun-Luh
Published: February 2005

The carrier transport model of tunneling oxide in a polysilicon-oxide-nitride-oxide-silicon (SONOS) device has been developed. The model is deduced from WKB approximation, and uses Fermi-Dirac statistics. Using the J-E and accompanied by Arnett's trapping model, the switching behavior of the SONOS device can be predicted in a very wide range of switching times from 1 µs to 0.1 s. The steady-state charge distribution and electric field in Si3N4 are also calculated. From Arnett's fundamental equations of Si3N4, we deduce the steady-state equations which describe the electric field and trapping charges. The trapping parameters and detrapping factor ν are discussed and the results are obtained via computer for different temperatures and stress voltages, which are based on the current measurement of SONOS devices. We find that the detrapping effect is somewhat less dominant compared to the trapping effect in our simulations.
Nanometer-Scale Deposition of Ga on HF-Treated Si(111) Surfaces through the Decomposition of Triethylgallium by Scanning Tunneling Microscopy
Authors: Uesugi Katsuhiro , Sakata Kiyoshi , Kawano Seiji , Masamichi Yoshimura Masamichi Yoshimura , Takafumi Yao Takafumi Yao
Published: February 2005

Ga dots on a nanometer scale were deposited using a scanning tunneling microscope (STM) through the decomposition of triethylgallium (TEGa) adsorhed on HF-treated Si(111) surfaces. The deposition of Ga dots of 2-13 nm in diameter was achieved by applying a negative voltage pulse to the sample, while no deposition was observed when a positive voltage pulse was applied. The conditions for Ga deposition were systematically investigated by varying the gap conductance, pulse height and pulse width. A tentative model for the mechanism of Ga deposition is proposed, in which TEGa molecules are decomposed by the electric field betwecn the tip and the sample.
Influences of Indium Tin Oxide Layer on the Properties of RF Magnetron-Sputtered (BaSr)TiO3 Thin Films on Indium Tin Oxide-Coated Glass Substrate
Authors: Kim Tae Song , Oh Myung Hwan , Chong Hee Kim Chong Hee Kim
Published: February 2005

Nearly stoichiometric ((Ba+Sr)/Ti=1.08-1.09) and optically transparent (BaSr)TiO3 thin films were deposited on an indium tin oxide (ITO)-coated glass substrate by means of rf magnetron sputtering for their application to the insulating layer of an electroluminescent flat panel display. The influence of the ITO layer on the properties of (BaSr)TiO3 thin films deposited on the ITO-coated substrate was investigated. The ITO layer did not affect the crystallographic orientation of (BaSr)TiO3 thin film, but enhanced the grain growth. Another effect of the ITO layer on (BaSr)TiO3 thin films was the interdiffusion phenomenon, which was studied by means of secondary ion mass spectrometry (SIMS). As the substrate temperature increased, interdiffusion intensified at the interface not only between the grown film and ITO layer but also between the ITO layer and base glass substrate. The refractive index (n
f) of (BaSr)TiO3 thin film deposited on a bare glass substrate was 2.138-2.286, as a function of substrate temperature.
Molecular Orientations of 1,4-dithioketo-3,6-diphenyl-pyrrolo-[3,4-c]-pyrrole on Crystalline Substrates
Authors: Fukushima Kotaro , Arita Masashi , Hiroshi Yamamoto Hiroshi Yamamoto
Published: February 2005

Molecular orientations of 1,4-dithioketo-3,6-diphenyl-pyrrolo-[3,4-c]-pyrrole deposited onto crystalline substrates have been studied. On alkali halide substrates, there are certain azimuthal relations between the substrates and the deposited films. For example, the films on KCl and KBr have special orientations to the substrates, where the a-axes of the films are nearly parallel to <8 15 0> (or <1 1 0>) of KCl and <7 2 0> of KBr, respectively. These relations are discussed using a geometrical boundary theory applied on the thin films and the substrates.
Propagation Characteristics and Mode Utilizability of Electromagnetic RF and Optical Surface Waves Travelling between a Pair of Metal Sheets
Authors: Shigehiko Nonaka Shigehiko Nonaka
Published: February 2005

Several characteristic features of electromagnetic (EM) surface waves propagating between a pair of planar conductors are disclosed analytically along with the other normal EM modes. The solutions are obtained on the basis of electron plasma oscillation in metals. The results are summarized as follows: (I) there exist primarily two independent surface waves (or optical surface waves), even and odd surface modes; (II) the odd surface mode (SWo) becomes a pure transverse electromagnetic (TEM) wave in the limiting case of an infinite value of electron density in metals; and (III) the even surface mode (SWe) will smoothly change to the even TM1e mode at a certain point of the dispersion curve. Utilizability of the lower modes is discussed for very-high-frequency RF and optical wave transmission lines and for long or large-area plasma production between planar electrodes.
Electronic States of Si(001)2×1-C60 Surface
Authors: Tsuyoshi Yamaguchi Tsuyoshi Yamaguchi
Published: February 2005

Electronic states of a model cluster C60Si39H32 of the Si(001)2×1-C60 surface are calculated by the DV-Xα-LCAO method. Electrons transfer from the Si surface to C60 molecules. The molecule has an ionicity of C60
-2.18. The highest occupied molecular orbital (HOMO) is the dangling bond orbital of the Si surface. Eight occupied orbitals of the C60 molecule near the HOMO have high bondinglike charge density around double bonds between two hexagons and low charge density around single bonds on pentagons. Seven unoccupied orbitals of the C60 molecule near the HOMO have high antibondinglike charge density around double bonds but low charge density around single bonds. The resultant charge density seems to be high around single bonds.
Growth Processes of Si(111)-√3×√3-Ag Studied by Scanning Tunneling Microscope
Authors: Ohnishi Hideaki , Katayama Itsuo , Ohba Yasuyuki , Fumiya Shoji Fumiya Shoji , Kenjiro Oura Kenjiro Oura
Published: February 2005

Domain growth processes of Si(111)√3×√3-R30°-Ag surfaces and their dependence upon deposition conditions have been investigated by means of scanning tunneling microscope. When Ag is deposited at room temperature, small islands are formed on the terraces. After annealing at 350°C, these small islands change into √3-Ag domains on the terraces without diffusion of Ag atoms to the step edges. On the other hand, when Ag is deposited on a hot substrate of about 350°C, the √3-Ag domains nucleate at the step edges and few √3-Ag domains are observed on the terraces. Moreover, two kinds of √3-Ag domains are found in either case: one domain is geometrically higher than the other domain.
Adsorption of Bismuth on Si(110) Surfaces Studied by Scanning Tunneling Microscopy
Authors: Sakama Hiroshi , Kawazu Akira , Sueyoshi Takashi , Sato Tomoshige , Iwatsuki Masashi
Published: February 2005

Bi-adsorbed Si(110) surfaces are investigated by scanning tunneling microscopy (STM). The 2×3 structures where two protrusions are observed in a unit cell at the positive and negative sample bias voltages are formed at 700 K. The up and down terraces of the clean 16×2 structure still remain when Bi atoms are deposited at room temperature, while a rather flat surface with boundaries parallel to [-1, 1, 2] (or [1, -1, 2]) is formed by the adsorption of Bi at 570 K. The 2×3 structures of short-range order are also formed on the flat surface at 570 K.
Scanning Tunneling Microscopic Observations of “Nonconductive” Oxide Surfaces: SiO2 Thin Films Formed on n- and p-Si(100)
Authors: Komiyama Masaharu , Manabu Kirino Manabu Kirino , Hiroyuki Kurokawa Hiroyuki Kurokawa
Published: February 2005

Scanning tunneling microscopy (STM) observations for “nonconductive” silicon oxide (silica) surfaces under ambient conditions were attempted. Thin (approximately 0.6 nm thick) silica films spontaneously formed on p- and n-type Si(100) surfaces were employed as silica samples. X-ray photoelectron spectra from these native-oxide-covered Si surfaces indicate that the valence band edges of the silica thin films are located at the binding energies of 3.0-3.3 eV. In the STM bias voltage dependence of the tip-sample distance on these surfaces under constant current, features attributable to conduction band edges of the silica films are observed at 2.5-3.5 eV above the Fermi edge. From these data it is conjectured that at the bias voltages beyond the range of approximately ±3.5 V, it may be possible to obtain the surface images of these thin silica films by means of STM. Silica surface images thus obtained was presented and discussed.
Scanning Tunneling Microscope and Atomic Force Microscope Observation of Topography of Molecular-Beam-Epitaxy-Grown Pt Films on Cu Buffer Layer and Si(111)-(7×7) Substrate
Authors: Nishikawa Kouichi , Yamamoto Masahiko , Kurumizawa Toshimitsu , Kingetsu Toshiki
Published: February 2005

Topography of Pt films on a Cu buffer layer and Si(111)-(7×7) substrate has been observed by use of scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Changes in topography with increasing thickness of the Pt film are described. Topography of a Cu buffer layer is also described. The existence of two kinds of bands, due to the off-angle of the Si substrate, is shown. As microstructures within the bands, Pt films have a dendritic structure in the early stages of the increase of Pt film thickness, and in the later stages, a number of truncated triangular pyramids of Pt are formed all over the surface of the Pt film.
Atomic Force Microscopy Imaging of Filamentous Aggregates from an N-Terminal Peptide Fragment of Barnase
Authors: Shibata-Seki Teiko , Masai Junji , Yoshida Kenji , Sato Kazuki , Yanagawa Hiroshi
Published: February 2005

This paper reports the atomic force microscopy (AFM) imaging of filamentous aggregates derived from an N-terminal peptide fragment of barnase, a ribonuclease from Bacillus amyloliquefaciens. The sample was deposited on a freshly cleaved mica surface and observed in ambient conditions. The overall shapes of the filamentous structures imaged with two different kinds of AFMs were similar to those obtained with a transmission electron microscope (TEM), except that the filaments in AFM images were broader than those in TEM images. This broadening phenomenon characteristic of AFM images was explained in terms of the convolution-type distortion of the specimen diameter by the scanning-tip apex.
Atomic Force Microscope Combined with Scanning Tunneling Microscope [AFM/STM]
Authors: Morita Seizo , Yasuhiro Sugawara Yasuhiro Sugawara , Yoshinobu Fukano Yoshinobu Fukano
Published: February 2005

Recently we developed a scanning force/tunneling microscope (AFM/STM), wherein the scanning tunneling microscope (STM) is combined with the atomic force microscope (AFM). This AFM/STM system enables investigation of the surface corrugation by AFM and the local conductance by STM in the same microscopic area with nanometer resolution. In the present paper, we report on the AFM/STM application to the characterization of semiconductor surfaces in air with inhomogeneous conductance and with a thin oxide film. As a result, the potential of the AFM/STM for investigating inhomogeneous conductance of ion-implanted Si(100) surfaces was clarified. Moreover the process dependence of oxidation sites on poly-Si surfaces and the voltage-dependent phenomena of thin Si oxide such as contact electrification, corona discharge and dielectric breakdown were studied.
Al Etching Characteristics Employing Helicon Wave Plasma
Authors: Jiwari Nobuhiro , Iwasawa Hiroaki , Narai Akira , Sakaue Hiroyuki , Shindo Haruo , Shoji Tatsuo , Yasuhiro Horiike Yasuhiro Horiike
Published: February 2005

Characteristics of helicon wave plasma employing Cl2 gas and its application to Al etching have been studied. Production of Cl ions dominates that of Cl atoms at 1200W RF power at 2 mTorr. Liberated oxygen from a quartz tube sputtered with Cl ions oxidizes Al and the probe surface. This is overcome by adding 10% BCl3 to Cl2. Electron density, temperature and ion current in Cl2 plasma at 2 mTorr are 5×1010 cm-3, 5.5 eV and 15 mA/cm2, respectively. Formation of negative chlorine is dominant at higher pressure. Although the Al etch rate is 5000 Å/min, selectivity to resist and SiO2 is poor due to high substrate bias voltage. Initiation time depends strongly on bias voltage, while net etching time is not changed. This implies that Al etching follows a chemical reaction even at 2 mTorr. Considerably uniform etch rate was achieved in zero magnetic field in a reactor. Slight variation which may result in the helicon wave plasma was observed.
Local Electric Field Effect in Reactive Ion Etching
Authors: M. Ardehali M. Ardehali , H. Matsumoto H. Matsumoto
Published: February 2005

We present unambiguous evidence that under reactive ion etching conditions, i.e., P≤75 mTorr, the perturbation of the local electric field by the geometric shape of the trench has very little influence on ion trajectories and hence on the etching rate. This local electric field effect is negligible even for trenches with depths as large as 50 µm, and even for incident ions with energies as small as 20 eV. These results are in sharp disagreement with the previous models in the literature.
Porous β-SiC Fabrication by Electrochemical Anodization
Authors: Takazawa Akira , Tetsuro Tamura Tetsuro Tamura , Masao Yamada Masao Yamada
Published: February 2005

It was found for the first time that a porous β-SiC layer was formed on a single-crystalline β-SiC surface by anodic dissolution in a HF solution. Observations using scanning electron microscopy revealed that the as-anodized β-SiC had a porous structure with the minimum size of about 20 nm.
Frequency Dependence of Resistivity of High-Purity Copper at Low Temperatures
Authors: Nakane Hiroshi , Watanabe Tsuneo , Kobayashi Mineo , Hashimoto Takasu
Published: February 2005

The frequency dependence of the surface impedance of different kinds of high-purity copper was measured in the audio frequency region and at low temperatures. The impedance of a coil with and without a rod-shaped sample was measured as a function of frequency. From these values, the surface impedance for copper of different purities was calculated. It was found that the real part of the difference in the coil impedance is proportional to ω
n
, where ω is the angular frequency and n ranges from 1/2 (normal skin effect) to 2/3 (anomalous skin effect). This finding suggests that the surface impedance of high-purity copper at low temperatures can be better explained in terms of the anomalous skin effect than the normal skin effect.
Development of Micro-Coil Sensor for Measuring Magnetic Field Leakage
Authors: Hirota Tetsuya , Siraiwa Toshio , Hiramoto Kazuo , Ishihara Michiaki
Published: February 2005

A magnetic sensor has been developed to detect magnetic leakage flux from cracks on the surface of steel products. This sensor is manufactured employing technology and equipment used for semiconductor microdevices. The sensor has a high sensitivity compared with conventional semiconductor sensors and coil sensors.
HF-Treated (111), (110) and (100)Si Surfaces Studied by Spectroscopic Ellipsometry
Authors: Katsuyuki Utani Katsuyuki Utani , Sadao Adachi Sadao Adachi
Published: February 2005

Spectroscopic ellipsometry (SE) has been used to study chemical (or structural) differences in HF-treated Si surfaces with three different crystallographic orientations, (111), (110) and (100). The observed orientation-dependent SE data are tentatively explained in terms of two causes: the differences in the H-terminated Si (dangling bond) densities and the degree of surface roughness produced by the HF treatment. The HF-treated Si surfaces are also found to become hydrophobic if the surface oxides are completely removed. However, no clear orientation dependence of the wettability has been found among these surface orientations.
Measurement of Abrupt Change of Carrier Concentration by C-V Method
Authors: Sasaki Yukio , Harunori Sakaguchi Harunori Sakaguchi , Shoji Kuma Shoji Kuma
Published: February 2005

Depth profiles of semiconductor wafers with abrupt change of carrier concentration are generally shown to be dull by C-V measurement. A new method of analysis of profile measurement considering changes of internal potential (E
g-E
F) is proposed. Using this analysis, abrupt profiles of a GaAs epitaxial wafer and a Si-ion-implanted GaAs wafer are successfully obtained.
Thermal Diffusivity Measurement of a Thin Film in the Direction across the Film by AC Calorimetric Method
Authors: Kato Ryozo , Hatta Akikazu Maesono
Published: February 2005

A method utilizing ac calorimetry for measuring thermal diffusivity of a thin film in the direction across the film is proposed based on both theoretical analysis and experimental examination. The sample system is composed of three parts: a medium, a thin film sample and a second medium. For precise measurement, it is essential that one of the two media is made of the same material as the thin film sample. With this system, a thin polyimide film with thickness of 75 µm was experimentally examined in the frequency range from 4 to 140 Hz at room temperature. The standard deviation of the analyzed thermal diffusivity was less than 0.2%. The value of the thermal diffusivity is consistent with that obtained with a laser flash method.
Inductive Inference Scheme Based on Spontaneous Fluctuation of a Probabilistic Neural Network
Authors: Yamanaka Masahiro Agu
Published: February 2005

It is shown that spontaneous fluctuation of the neural excitation pattern of a probabilistic neural network can be the source or seed for generation of information in order to perform a kind of inductive inference. A primary model of the inductive inference scheme is proposed and applied to a pattern restoration problem. Results of computer simulation suggest the validity of the proposed model.
Magnetic Properties and Recording Characteristics of Co-Cr-Ta-Pt Thin Film Media
Authors: Inase Toshio , Kentaro Ustumi Kentaro Ustumi , Akio Kondo Akio Kondo
Published: February 2005

Magnetic properties and recording characteristics of Co-Cr-Ta-Pt film for high-density recording media were investigated. It was found in this study that high coercivity of more than 1800 Oe can be obtained by addition of 3 at.% Pt and deposition at 250°C. The increase of coercivity by the addition of Pt atoms is considered to be due to the increase of magnetic anisotropy. The cause of high coercivity of the samples deposited at high substrate temperature is considered to be the growth of hcp(11.0) parallel to the film plane. It was also found that Co-Cr-Ta-Pt media had lower media noise level than Co-Cr-Pt media and that the media noise level of Co-Cr-Ta-Pt can be reduced to the same level as in Co-Cr-Ta media by increasing Cr composition.
Ring-Type Ti:sapphire Regenerative Amplifier with a Wide Tuning Range
Authors: Nakamura Shinki , Midorikawa Katsumi , Minoru Obara Minoru Obara , Koichi Toyoda Koichi Toyoda
Published: February 2005

Using a chirped pulse amplification technique, we have constructed a Ti:sapphire regenerative amplifier with a ring cavity. The amplified pulses with an energy of 4 mJ were compressed to 120 fs at 797 nm and 170 fs at 746 nm. The spectral distortion in the amplifier and the compressed pulse shapes were investigated at the two different wavelengths.
Wall Temperature Dependence of Boronization Using Decaborane and Diborane
Authors: Yamage Masashi , Ejima Takeshi , Saidoh Masahiro , Ogiwara Norio , Hideo Sugai Hideo Sugai
Published: February 2005

A new boronization technique based on pyrolysis of boron hydrides on hot walls was investigated in a laboratory experiment. The deposition rate of boron films through pyrolysis of decaborane was high enough to apply the pyrolysis to actual fusion devices bakable to 300°C. The hydrogen concentration of boron films prepared by the pyrolysis or conventional plasma-assisted boronization at various temperatures was measured with 15N nuclear reaction and/or IR absorption methods. The hydrogen content markedly decreased with increasing wall temperature, where decaborane always gives higher H content than diborane. Oxygen gettering and hydrogen recycling in a boronized vessel were evaluated by pulsed glow discharge in O2/He and D2, respectively. The results were compared between the pyrolysis and the plasma-based boronizations in decaborane or diborane at various wall temperatures.