bluuebunny/crossref_metadata_2025 huggingface dataset:
Pd–Ni–Si–Be–B Liquid Metal Ion Source for Maskless Ion Implantation
Authors: Arimoto Hiroshi , Takamori Akira , Miyauchi Eizo , Hashimoto Hisao
Published: November 2005

A new type of alloyed liquid metal ion source for maskless ion implantation into III-V compound semiconductors has been developed. An alloy consisting of Pd, Ni, Si, Be and B is used as the liquid metal for this ion source, which can offer B ions for device isolation as well as Si ions (n-type dopant) and Be ions (p-type dopant) from a single emitter tip. With this ion source, a submicron width high resistivity layer has been obtained by implantation of B ions using a beam of 0.1 µm diameter.
Fe–Nd–Ti Films with Perpendicular Magnetic Anisotropy
Authors: Tsutsumi Kazuhiko , Sugahara Hiroshi
Published: November 2005

Fe–Nd–Ti thin films with perpendicular magnetic anisotropy have been prepared by rf sputtering. Though Fe–Nd films has its easy axis of magnetization in the film plane, the addition of Ti to Fe–Nd causes the film to have an easy axis of magnetization in the normal to the film plane. The structure of Fe–Nd-Ti film is detected to be partially crystallized in amorphous alloy matrix.
Scanning Electron Microscope Observation of Magnetic Domains Using Spin-Polarized Secondary Electrons
Authors: Koike Kazuyuki , Hayakawa Kazunobu
Published: November 2005

A new method for observing magnetic domain structures with a scanning electron microscope has been developed in which the image is the result of spin polarization of secondary electrons. With this method the domain structures on an iron (001) surface have been observed. At present, spatial resolution is not less than 10 µm, but can be expected to be reduced to far less than that of both conventional electron microscopic and optical reflection methods.
Homogeneity of Vertical Magnetic Field Applied LEC GaAs Crystal
Authors: Osaka Jiro , Kohda Hiroki , Kobayashi Takashi , Hoshikawa Keigo
Published: November 2005

The effect of a vertical magnetic field on both GaAs melt temperature distribution and the homogeneity of LEC GaAs crystals is studied. It is found that although melt flow fluctuations that introduce irregular striations can easily be eliminated, laminar thermal convection cannot be completely suppressed by the magnetic field. This residual laminar thermal convection degrades both microscopic and macroscopic homogeneity of crystals. However, striation-free crystals having a doped Se concentration variation of less than 2.5% across the wafer are obtained by optimizing the seed rotation rate in the presence of such a magnetic field.
Calculation of Bond Length in Ga1-xInxAs Ternary Semiconductors
Authors: Fukui Takashi
Published: November 2005

A simple model for calculating the nearest neighbor bond length in ternary semiconductors is presented. Calculated bond lengths for Ga1-x
In
x
As agree well with experimental data by EXAFS. The change in bond lengths for Ga0.5In0.5As is only 21%, compared with that calculated using the virtual-crystal approximation approach. Using this model, the change in bond length and bond angle for other ternary zincblend structure alloys can also be easily estimated without using EXAFS.
Time Dependent Small Angle X-Ray Scattering Study in Poly (methyl Methacrylate) under Uniaxial Tensile Stress
Authors: Shichijyo Shiro , Matsushige Kazumi , Takemura Tetuo
Published: November 2005

Time dependent small angle x-ray scattering was conducted on poly (methyl methacrylate) (PMMA) at constant strains to study the micromechanism of the stress relaxation phenomenon. The application of strain induced a rapid nucleation of submicrocracks with lens-like shape (over 1000 Å in diameter and about 600 Å in thickness), and the correlation between the increase in submicrocrack concentration and the stress relaxation process was clarified quantitatively. These results suggest that in brittle polymers such as PMMA, the formation of submicrocracks plays a decisive role in the stress relaxation phenomenon.
Growth of Low and Homogeneous Dislocation Density GaAs Crystal by Improved LEC Technique
Authors: Shimada Takashi , Terashima Kazutaka , Nakajima Hiroaki , Fukuda Tsuguo
Published: November 2005

An improved LEC technique of enhanced heating of B2O3 encapsulant layer through the windows of susceptor cylinder is described. By this technique, low temperature gradients of 10∼25°C/cm in the axial direction and 5°C/cm in the radial direction were achieved. Two-inch diameter crystals grown by this technique with a slow cooling rate exhibited quite low dislocation density of 8×103 to low 104 cm-2 order from front to tail of the crystal.
Proposed GaAs–Al–GaAs Metal Base Transistor
Authors: Chen Z. H. , Smith J. S. , Margalit S. , Yariv A. , Chiu L. C.
Published: November 2005

The potential and feasibility of a metal base GaAs–Al–GaAs transistor are discussed. The transistor is capable of ultra-high speed performance primarily due to the reduced base resistance and elimination of the base contact resistance.
Composition-Modulated Structures in InGaAsP and InGaP Liquid Phase Epitaxial Layers Grown on (001) GaAs Substrates
Authors: Ueda Osamu , Isozumi Shoji , Komiya Satoshi
Published: November 2005

InGaAsP and InGaP epitaxial layers lattice-matched to (001)-oriented GaAs substrates successfully grown by liquid phase epitaxy have been investigated by transmission electron microscopy, scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. In both layers, periodic diffraction contrasts (modulated structures), are observed in two equivalent directions of the <100> and the <010>. Compositional variation has also been observed along these structures. These are associated with spinodal decomposition of the crystal during growth.
Perpendicular Magnetic Anisotropy in γ-(Fe1-xOsx)2O3 Thin Films
Authors: Ishii Osamu , Yoshimura Fumikatsu , Terada Akira
Published: November 2005

This letter reports preparation of γ-(Fe1-x
Os
x
)2O3 thin films that have easy axis of magnetization normal to the film plane. This unusual condition was the result of magnetic annealing under an external field of 10 kOe perpendicular to the film plane. The optimum annealing temperature and Os content, x, to obtain film with a large perpendicular anisotropy were about 400°C and 0.05, respectively. Read/write characteristic measurement of film with ring head exhibited a dipulse waveform, confirming perpendicular magnetic recording.
Thermally Stimulated Current in Polyethylene Terephthalate Electrets Formed by AC Electrical Fields
Authors: Maeda Akinori , Kojima Kenzo , Takai Yoshiaki , Ieda Masayuki
Published: November 2005

Thermally stimulated current (TSC) in polyethylene terephthalate (Au-PET-Al) was investigated with excitation by AC electric field. Two TSC peaks were observed above room temperature and were ascribed to the release of trapped electrons injected from the Al electrode. This TSC analysis with AC electric field excitation can easily evaluate the peak of trapped electronic carriers separating from other peak due to dipolar polarization.
Structural Evaluation of GaAs/AlGaAs Heterointerfaces by Atomic-Resolution Electron Micrograph with Clear Contrast
Authors: Furuta Tomofumi , Sakaki Hiroyuki , Ichinose Hideki , Ishida Yoichi , Sone Mitsuo , Onoe Morio
Published: November 2005

Transmission electron microscopy observation was made on GaAs/AlGaAs heterostructures which were grown on (001) GaAs by molecular beam epitaxy. A lattice image with a clear contrast was obtained for the first time. It was found that heterostructures were free from crystal defect both in layers and at interface. By performing a digital image analysis on lattice image, the compositional grading and/or the height of interface roughness were estimated and found to be less than ±1.25 atomic layers.
Photoemission of Cs Valence Electrons from a Cs Monolayer on Si(111) 2×1
Authors: Tochihara Hiroshi , Kubota Masakazu , Aruga Tetsuya , Miyao Masahiro , Murata Yoshitada
Published: November 2005

The adsorption of Cs atoms on the Si(111) 2×1 surface has been studied by photoelectron spectroscopy using synchrotron radiation. A photoemission peak due to Cs 6s valence electrons is clearly observed at full monolayer coverage by tuning photon energy at around 50 eV over an available energy range from 30 to 130 eV. The peak appears at almost the same initial energy (-1 eV) as that of the surface state of the clean Si(111) 2×1 surface. It is shown that the insulator-metal transition in the Cs monolayer takes place with increasing coverage.
Correlation between Surface Morphology and Electrical Properties of GaAs Grown by Metalorganic Chemical Vapor Deposition
Authors: Mizuta Masashi , Kawata Seiji , Iwamoto Takashi , Kukimoto Hiroshi
Published: November 2005

Surface morphology, including growth pyramids and rough surface, formed on MOCVD grown GaAs epitaxial layers has been investigated for different ratios of As to Ga atoms during growth. Such a morphology is correlated with the electrical property of the film. More specifically, rough surface textures together with p-type conductivity of the undoped sample result simultaneously for smaller As to Ga ratios. The effect of the As to Ga ratio on surface morphology and conductivity-type conversion is different for different orientations of substrates. This fact and the formation of the growth pyramids are explained on the basis of a local deficiency of As at the growth surface.
Characterisation of Stoichiometry in GaAs by X-Ray Intensity Measurements of Quasi-Forbidden Reflections
Authors: Fujimoto Isao
Published: November 2005

Deviation from stoichiometry in GaAs was detected in an accuracy of c
Ga-c
As=3×10-5 by measuring variations of integrated intensities of weak quasi-forbidden reflections of X-rays. Fairly large deviations of the order of 10-4 with higher atomic concentrations in As lattice planes were found for undoped semi-insulating liquid-encapsulated Czochralski (LEC) grown crystals compared with horizontal Bridgaman (HB) grown ones. The radial distribution of the deviation in a wafer was observed to have a total correlation with the distribution of dislocations. Capability of the method is demonstated by results obtained for epitaxial layers grown by VPE, LPE and MBE.
Deep Electron Traps in Undoped GaAs Grown by MOCVD
Authors: Hashizume Tamotsu , Ikeda Eiji , Akatsu Yuji , Ohno Hideo , Hasegawa Hideki
Published: November 2005

Deep electron traps in undoped GaAs grown by metalorganic chemical vapor deposition (MOCVD) have been investigated using DLTS measurement. Five electron traps were detected. The dominant trap shows an activation energy of 0.80±0.02 eV, which is probably the same level as EL2 in conventional VPE GaAs layers. The remaining four traps were only observed in samples grown with a particular trimethylgallium (TMG) source, and were below the detection limit (5×1011-5×1012 cm-3) with other TMG sources. These results strongly indicate that the four traps are due to impurities in the source material.
Mechanism of High Gain in GaAs Photoconductive Detectors under Low Excitation
Authors: Matsuo Nozomu , Ohno Hideo , Hasegawa Hideki
Published: November 2005

Very high photoconductive gain of about 104–105 is observed in GaAs photoconductive detectors for low photon flux density of 1015–1017 photons/(cm2·s). This high gain decreases with increasing photon flux density. A model is proposed which includes carrier separation by surface band dending and surface recombination of photogenerated carriers controlled by surface barrier height. This model is shown to quantitatively explain the photon flux density dependence of both high gain and response time.
Vertical Magnetic Field Applied LEC Apparatus for Large Diameter GaAs Single Crystal Growth
Authors: Terashima Kazutaka , Katsumata Tooru , Orito Fumio , Fukuda Tsuguo
Published: November 2005

A new vertical magnetic field applied LEC apparatus has been developed for volume production of large size GaAs single crystals. The apparatus consists of a superconducting magnet with compact refrigerator systems and an in-house modified high pressure puller. Temperature fluctuation through the molten GaAs was suppressed to less than 0.3°C by the application of more than 1000 Oe. The vertical magnetic field effects on GaAs melt are described in comparison with the results of a transverse magnetic field.
Plasma Shapes for Achieving High Heating Efficiency during Neutral Beam Injection in Doublet III
Authors: Yokomizo Hideaki , Konoshima Shigeru , Aikawa Hiroshi , Kasai Masao , Ninomiya Hiromasa , Kobayashi Tomofumi , Matsuda Toshiaki , Miya Naoyuki , Nagami Masayuki , Shimada Michiya , Kitsunezaki Akio
Published: November 2005

Three plasma configurations have been compared for achieving an improved heating efficiency (H-mode) during the neutral beam injection phase. The H-mode plasmas are observed only in divertor configurations. The highly elongated divertor shape has achieved H-mode plasmas with the best heating efficiency. Required beam power for achieving these plasmas increases from ∼1 MW to ∼4 MW as the plasma current increases from 360 kA to 740 kA. The stored plasma energy increases as the plasma current increases and improves 50% over that in low heating efficiency (L-mode) at the best H-mode discharges.
Composite Josephson Device
Authors: Nakanishi Masakazu , Hara Ko
Published: November 2005

A superconductive loop circuit including more than four Josephson junctions (JJ), which is called a Composite Josephson Device (CJD), can support a fluxoid stably without inductance and has multiple stable states depending on the number of fluxoids. One of the simplest cases of CJD with a three-terminal six JJ loop device is analyzed numerically. The result shows that it has five stable areas and is able to operate as a current amplifier within a certain parameter range.
NbN/Nb Josephson Junction with a Plasma Oxidized Barrier
Authors: Iwata Tsunekazu , Takei Koji , Igarashi Masaru
Published: November 2005

Oxide growth on a niobium nitride film formed by rf plasma oxidation was studied using NbN/Nb-oxide/Nb tunnel junctions. A model of the oxide growth on niobium nitride is discussed to compare the oxidation on a film with a pre-oxidized layer formed by thermal oxidation and a film without the pre-oxidized layer. Using a thermally pre-oxidized layer, a junction with high critical current density can form with good controllability.
Preferential Desorption of Ga from AlxGa1-xAs Grown by Molecular Beam Epitaxy
Authors: Kawabe Mitsuo , Matsuura Nobuyuki
Published: November 2005

Substrate-temperature dependence of surface and bulk composition of Al
x
Ga1-x
As grown by molecular beam epitaxy has been studied by auger electron spectroscopy and photoluminescence. Ga desorption during epitaxial growth is not negligible at the substrate temperature above 650°C. The surface Ga density of as-grown Al
x
Ga1-x
As is less than that of the bulk due to the Ga desorption after Ga flux is stopped. When the epitaxial wafer is kept at the growth temperature (above 690°C) for a few minutes without Al and Ga fluxes and with As4 flux, the surface is covered with approximately three monolayers of AlAs due to desorption of Ga.
Thickness Dependence of SiO2 Capping Layers on Recrystallization of Germanium Islands on Insulator
Authors: Takai Mikio , Tanigawa Takaho , Gamo Kenji , Namba Susumu
Published: November 2005

The thickness of SiO2 capping layers has been varied to suppress agglomeration and surface rounding of germanium layers on SiO2 during zone melting recrystallization. It was found that SiO2 capping with a thickness of more than 1 µm could suppress agglomeration and surface rounding successfully and most of the islands were single crystalline with flat surfaces. The predominant orientation of germanium islands was found to be (100).
Growth and Properties of Undoped n-Type ZnSe by Low-Temperature and Low-Pressure OMVPE
Authors: Fujita Shigeo , Matsuda Yoshinobu , Sasaki Akio
Published: November 2005

Undoped ZnSe epitaxial layers have been grown at a temperature as low as 250°C onto (100)GaAs substrates by a low-temperature and low-pressure organometallic vapor-phase epitaxial (OMVPE) technique using dimethylzinc (DMZ) and H2Se as source materials. The epilayers have exhibited strong blue emission and low resistive n-type conductivity. Typical values of the electron concentration n, the resistivity p, and the electron Hall mobility µ are n=8.2×1016 cm-3, p=0.31 Ω·cm, and µ=244 cm2/V·s, respectively.
Residual Strain in Single Crystalline Germanium Islands on Insulator
Authors: Takai Mikio , Tanigawa Takaho , Miyauchi Michihiro , Nakashima Shin-ichi , Gamo Kenji , Namba Susumu
Published: November 2005

Residual strain in single crystalline germanium islands, recrystallized by zone melting, on SiO2 substrates has been investigated by Raman microprobe measurements with a spatial resolution of 5 µm. It was found that strain of 3.0×10-3–6.0×10-3, corresponding to local tensile stress of 2.3 to 4.6 kbar, remained in single crystalline germanium islands after zone melting recrystallization.
Generation of Pulsed Ion Beams from Various Dielectric Materials Cooled with Cryogenic Anode
Authors: Horioka Kazuhiko , Takahashi Tsutomu , Kasuya Koichi , Mizui Junichi , Tazima Teruhiko
Published: November 2005

A cryogenic magnetically insulated B
r diode was operated successfully at 2 GW power level by a “LIMAY-I” pulsed power generator (IPP NAGOYA). The dielectric anode materials C
n
H2n+2, H2O, D2O, and C6H6 were tested as ion sources and it was confirmed that generated ion currents were affected by the molecular structure and the surface temperature of the anode materials.
Visualization of Defects in GaAs by Oxidation in Water
Authors: Fukuta Katsuyoshi , Yasuami Shigeru
Published: November 2005

Boiling GaAs wafers in deionized water creates oxide films on their surfaces. The thickness and color of the film depends upon the defect density in the wafer. The film thus depicts a pattern showing a good correspondence with the X-ray traverse topograph and etch pit pattern.
Millimeter and Submillimeter Cyclotron Resonance Study of High-Purity ZnSe
Authors: Ohyama Tyuzi , Otsuka Eizo , Yoshida Tomoaki , Isshiki Minoru , Igaki Kenzo
Published: November 2005

We have observed for the first time the electron cyclotron resonance in a high quality ZnSe crystal, using both millimeter and submillimeter waves. We obtain an isotropic effective mass m
*=0.145m
0. From linewidth measurement it is found that the cyclotron mobility at 4.2 K exceeds 2.3×105 cm2/Vs. A strong anisotropy in absorption intensity has been observed in 35 GHz measurement.
New and Simple MOCVD Technique Using Completely Gaseous MO-Sources Especially Useful for Growing Zn-Chalcogenide Films
Authors: Yoshikawa Akihiko , Yamaga Shigeki , Tanaka Keiji
Published: November 2005

A Simple and inexpensive MOCVD technique using completely gaseous MO-sources especially useful for growing Zn-chalcogenide and -oxide films is proposed. It is shown that the flow rate of MO-source material can be controlled more accurately and simply by this technique than in a conventional MOCVD technique using a bubbling-cylinder for MO-source. Its application for growing ZnS and ZnSe films is also shown. High-quality and low-resistivity ZnSe films are grown on GaAs substrates without intentional doping using this technique and show a strong blue near-band-edge photoluminescent peak.
TEM Investigation of Dislocation Loops in Undoped InGaAsP and InGaP Layers Grown by Liquid Phase Epitaxy
Authors: Ueda Osamu , Komiya Satoshi , Isozumi Shoji
Published: November 2005

Undoped InGaAsP and InGaP layers grown on (001)-oriented GaAs substrates by liquid phase epitaxy have been investigated by transmission electron microscopy. Two types of dislocation loops are observed in the same crystals as follows: interstitial type Frank loops with Burgers vectors of a/3<111> and vacancy type prismatic loops with Burgers vectors of a/2<101>. Most are generated in the region near the interface between the epitaxial layer and the substrate.
A New Perpendicular Magnetic Film of Co–O by Evaporation
Authors: Nakamura Kyuzo , Tani Noriaki , Ishikawa Michio , Yamada Taiki , Ota Yoshifumi , Itoh Akio
Published: November 2005

A new perpendicular magnetic film has been developed by an evaporation method using room temperature substrates. The film is obtained by partially oxidating the Co film with the oxygen gas introduced during deposition. The film structure is a mixture of very fine Co grains and CoO phase. The obtained films have such superior perpendicular magnetic properties as H
c⊥=1100 Oe, H
k=5.5 kOe and 4πM
s=6000 G at Co–45 at%O film composition.
Focusing Characteristics of X-Ray Zone Plates Fabricated by Electron Beam Lithography and Reactive Ion Etching
Authors: Aritome Hiroaki , Aoki Hitoshi , Namba Susumu
Published: November 2005

Focusing characteristics of zone plates fabricated by a new method using electron beam lithography are investigated by the He–Ne laser (632.8 nm), synchrotron radiation and the characteristic X-ray of carbon (4.47 nm). The measured spot size is that of the reduced image of the radiation source and the value can be close to the diffraction limited value by choosing the appropriate optical system. Focusing characteristics can be quantitatively well interpreted by using the lens formula.
A 400 kV High Resolution-Analytical Electron Microscope Newly Constructed
Authors: Bando Yoshio , Matsui Yoshio , Kitami Yoshizo , Inomata Yoshizo , Ibe Katsuhiko , Honda Toshikazu , Harada Yoshiyasu
Published: November 2005

A resolution limit of 0.23 nm has been achieved successfully by a newly constructed 400 kV analytical electron microscope equipped with an energy dispersive X-ray spectrometer. The characteristic of the new microscope is briefly described and structure images of H-Nb2O5
- and 6H-SiC crystals are obtained to show the observation capability of high resolution structure imaging.
High-Frequency Ultrasonic Transducer Operating in Air
Authors: Tone Masayuki , Yano Tsutomu , Fukumoto Akira
Published: November 2005

The design and application of high-frequency piezoelectric air transducers are described. By employing a double layer acoustic matching transformer to a ceramic thickness mode vibrator, an air transducer with low insertion loss (52 dB) and good RF pulse response (9 µs of -20 dB ring-down period) has been developed. Use of the transducer operating at 1 MHz for distance measurement in a range of 0∼20 cm has revealed that the range resolution and the measurement accuracy are 1.5 mm and of the order of 0.1 mm, respectively. Other applications described here are the characterization of cloth surfaces and profile measurement of cloths.
Hot Electron Energy Distribution in One-Dimensional Cannonball Target at 10.6 µm Laser Wavelength
Authors: Terai Kiyohisa , Daido Hiroyuki , Fujita Masayuki , Nishimura Hiroaki , Mima Kunioki , Nakai Sadao , Yamanaka Chiyoe
Published: November 2005

Hot electron energy distribution in one-dimensional Cannonball target irradiated by a 10.6 µm laser pulse was investigated by using a multilayered foil technique. The experimental results suggested that the energy distribution of hot electrons in the Cannonball target was quite different from that in the simple planar target. We found that the high energy tail was truncated due to the effects of the presence of front disk in the Cannonball assembly. It is expected that Cannonball targets can quite effectively suppress the hot electron preheating at 10.6 µm laser wavelength.
High Coercive Thin Films of Co-Doped γ-Fe2O3–Fe3O4 Solid Solution
Authors: Ohta Satoshi , Ishii Osamu , Terada Akira
Published: November 2005

Fe3+[Fe3+
1+2δFe2+
1-3δ
Δ
δ]O4 thin films have been prepared by oxidizing sputter-deposited magnetite, where Δ and δ indicate the vacancy and its content, respectively. The coercive force, H
c, exhibited the maximum value when δ was approximately 0.20. Films with a δ of more than 0.18 had only an infinitesimal H
c increase even after 6 years of aging at room temperature. It was surmised that enhanced Fe2+-Δ ordering stabilizes the H
c change with time. (Co0.023Fe0.977)2.80
Δ
0.20O4 films had a 1300 Oe H
c and 0.85 squareness ratio. These films are thought to be useful for high bit density magnetic disk application.
Reflow of PSG Layers by Halogen Lamp Short Duration Heating Technique
Authors: Hara Tohru , Suzuki Hidenori , Furukawa Masakazu
Published: November 2005

Reflow of 7 mol% P2O5 phosphosilicate glass (PSG) deposited on steep polysilicon steps was studied by halogen lamp short duration heating at temperatures ranging from 1050 to 1150°C. Reflow occurs after 60 s with 1050°C heating. Heating times required for reflow decrease rapidly with increased temperature and reach 40 and 15 s at 1100 and 1150°C, respectively. When heating is performed over a certain period, for instance, 80 s at 1100°C, reflow becomes excessive, leading to a breakdown voltage deterioration between Si gate electrodes and Al interconnections as well as a deeper source/drain junction depth. Optimum lamp heating times for adequately tapered contours were 40–80 s at 1100°C and 15–40 s at 1150°C.
Interfacial Reaction in Polycide MOS Gate Structure Employing CVD Tungsten Silicide
Authors: Hara Tohru , Enomoto Syuichi , Jinbo Toshikatsu
Published: November 2005

Interfacial reaction of a CVD WSi
x
polycide gate structure, WSi
x
(2200 Å)/polysilicon (4500 Å)/SiO2 (500 Å)/Si, has been studied by Rutherford backscattering spectroscopy technique. Annealing was done at temperatures of 900–1100°C in flowing dry N2. Slight interfacial reaction was observed at the WSi
x
-polysilicon interface with 1000°C annealing. At 1100°C annealing, however, in addition to this reaction, other reaction was also observed in gate oxide-polysilicon and/or gate oxide-substrate silicon interfaces. Composition of WSi
x
changed from nonstoichiometric (x=2.5) for as-deposited to stoichiometric (x=2.0–2.1) with annealing at temperatures above 900°C. Resistivity of CVD WSi
x
polycide layer was around 900 µΩ·cm for as-deposited, and decreased rapidly to 80, 60 and 42 µΩ·cm with 900, 1000 and 1100°C annealing, respectively.
Transient Photocurrent in Amorphous (As2Se3):Te Thin Films
Authors: Naito Hiroyoshi , Nakaishi Masafumi , Okuda Masahiro , Nakau Tanehiro , Matsushita Tatsuhiko
Published: November 2005

Effects on the transport properties and gap states in a-As2Se3 films produced by the additive Te (2 at.%, 4 at.%, 6 at.%) have been studied by measuring transient photocurrents with a time-of-flight technique. The experimental results are interpreted in terms of a trap-controlled band transport as the mechanism of the dispersive carrier transport in these films. It is found that as the amount of Te increases, the hole drift mobilities decrease, the profiles of gap states remain exponential and their characteristic temperature increases slightly.
OMVPE of Gallium Arsenide Using an Adduct Compound
Authors: Minagawa Shigekazu , Nakamura Hitoshi , Sano Hisumi
Published: November 2005

Organometallic vapor phase epitaxial (OMVPE) growth of gallium arsenide was conducted by making use of the reaction between an adduct compound : trimethygallium triethylphosphine and arsine. Characteristics of this growth process and the grown crystals were described in terms of growth rate, surface morphology, carrier concentration, electron mobility and photoluminescence spectra at 4 K. The highest mobilities obtained so far were 7000 cm2/(Vs) at 300 K and 47000 cm2/(Vs) at 77 K. The lowest carrier concentration was 5×1014 cm-3.
Deposition Mechanism of a-Si: H Film in Disilane-Hydrogen Plasma
Authors: Nakayama Yoshikazu , Takuma Yasuo , Akiyama Koji , Otsuchi Tetsuro , Kawamura Takao
Published: November 2005

Deposition mechanism of a-Si: H film in Si2H6–H2 plasma is investigated in terms of the deposition rate. It is found that the deposition rate is proportional to the square root of the electron concentration in the plasma at any Si2H6 fraction. This relation is interpreted by a simple model of film deposition including a reduction step of the concentration of effective radicals for film deposition by collision between two radicals in the gas phase. The Si2H6 fraction dependence of deposition rate at high Si2H6 fraction also suggests the existence of a production step of oligomeric radicals by radical collision with Si2H6.
CO2 Laser CVD of Disilane
Authors: Iwanaga Takehiko , Hanabusa Mitsugu
Published: November 2005

Amorphous silicon films were deposited by a CO2 laser CVD (chemical vapor deposition) method using disilane gas. With this gas, the films were deposited reasonably fast at relatively low substrate temperatures of 350°C or above. Unlike monosilane, photo-induced effects in the gas phase following light absorption were negligible in deposition processes, and only the pyrolytic process taking place at the laser-heated substrate was important. Some of the physical properties of deposited films were described.
(InAs)1(GaAs)1 Layered Crystal Grown by MOCVD
Authors: Fukui Takashi , Saito Hisao
Published: November 2005

(InAs)1(GaAs)1 layered crystals (LC) were successfully grown on (100) InP substrate for the first time. The growth method was metallorganic chemical vapor deposition (MOCVD). Monolayer growth was achieved by low growth rate and rapid change of gas composition. Layered crystals were confirmed by X-ray diffraction peaks at the (100) and (300) positions. The electrical and optical properties of (InAs)1(GaAs)1 LC were also studied.
Study of Thermal Symmetry in Czochralski Silicon Melt under a Vertical Magnetic Field
Authors: Hirata Hiroshi , Inoue Naohisa
Published: November 2005

A study is made of the effects of a vertical magnetic field on thermal symmetry in a Czochralski silicon melt. By application of a magnetic field of 2500 Oe, thermal asymmetry is reduced to about 1/2 that at 0 Oe, and isothermal contours become concentric circles. A model is proposed where a vertical magnetic field suppresses asymmetric thermal convection which degrades thermal symmetry, and heat transfer in the stagnant melt is dominated by symmetric heat conduction.
Comparison of Impact Ionization Current between PMOS and NMOS
Authors: Matsumoto Heihachi , Miyamoto Kazutoshi , Satoh Yoshihiro , Ishida Susumu
Published: November 2005

The differences of impact ionization current between PMOS and NMOS which have similar channel conductance are discussed in detail. It is not always true that PMOS is more free of the hot carrier problems than NMOS. PMOS has two orders of magnitude larger peak-gate-current than NMOS, which can be well explained by the lower barrier height and higher electric field in PMOS.
Evaluation of Boron and Phosphorus Doping Microcrystalline Silicon Films
Authors: Kaya Hiroshi , Imura Takeshi , Kusao Takashi , Hiraki Akio , Nakamura Osamu , Okayasu Yoshinobu , Matsumura Mitsuo
Published: November 2005

The change in structure and properties of doped µc-Si films with thickness increase were investigated by ESCA, TEM and IR methods. Dopant contents were analyzed by AES and IMA. The Fermi-level position of phosphorus doped µc-Si, evaluated from Si 2p binding energy by ESCA, was shifted by more than 0.3 eV to conduction band edge with the growth of microcrystallization. Phosphorus doping efficiency in µc-Si was better than that in a-Si at the same dopant density. On the contrary, the Fermi-level position of boron doped µc-Si was almost unchanged in spite of its microcrystallization in the deposition process and high doping.
Size of Crystalline Particle in Si-Implanted GaAs Estimated by Laser Raman Spectroscopy
Authors: Nakamura Tomoji , Katoda Takashi
Published: November 2005

The dependence of the peak intensity, full-width at half maximum (FWHM), and peak frequency of the LO phonon in Si implanted GaAs on the dose of Si and on the depth were studied by laser Raman spectroscopy. Raman spectra from almost crystalline particles were observed in all the samples that Si was implanted into at a current fluence between 2 and 400 nA cm-2 even if the dose is as large as 1×1016 cm-2. The minimum size of the crystalline particle can be estimated to be about 45∼50 Å. The size and density of the crystalline particles kept the minimum size and a constant value, respectively, from the surface to a depth of about 0.15 µm in spite of an increase in the intensity of a disorder-activated spectra.
Desorption Study of Carbon Monoxide from Molybdenum Surface by Means of Thermal Desorption Spectroscopy and Auger Electron spectroscopy
Authors: Ueda Kazuyuki , Kinoshita Keiji , Mega Tetsuya , Hashimoto Hatsujiro
Published: November 2005

A rapid scanning mass spectroscopy has been applied demonstratively to a dynamic change of thermal desorption spectroscopy (TDS). In order to obtain a carbon free surface of molybdenum, oxygen was adsorbed on the contaminated surface and subsequently heated. As a result of chemical reaction of carbon and oxygen on the surface, the desorption of carbon monoxide at 470±10°C was observed during heating. Auger signal also indicated a decrement of carbon on the surface.
Ion Beam Pulse Compression by Its Conversion into Soft X-Ray
Authors: Yabe Takashi
Published: November 2005

A new method to compress ion beam pulse is proposed, where ion beam of 1013 W/cm2 at 100 ns is converted into a focusable X-ray of 1014 W/cm2 at ∼10 ns. The method could be used for an energy focusing into a small volume and used in LIB (Light Ion Beam), HIB (Heavy Ion Beam) and even in KrF laser.
Frequency Stabilization of Dye Laser on Iodine by Background-Free First Derivative Signal
Authors: Morinaga Atsuo
Published: November 2005

The background remaining in the first derivative signal of saturated absorption was removed by means of the dual lock-in amplifiers in series, which were synchronized with a modulation frequency of the laser frequency and a chopping frequency of the saturating beam, respectively. Using the background-free first derivative signal, the dye laser frequency was stabilized to an iodine hyperfine transition with a small modulation width of 500 kHz. The frequency stability of 2×10-11 was obtained.
Glow-Discharge Deposition of Amorphous Silicon from SiH3F
Authors: Matsuda Akihisa , Yagii Kiyoshi , Kaga Takao , Tanaka Kazunobu
Published: November 2005

Glow discharge deposition of a-Si:H:F from SiH3F as well as SiH2F2 gas has been studied in comparison to that from SiH4. Deposition rate from SiH3F exceeds that from SiH4 by 2–3 times in magnitude under a low-power deposition condition.
Role of Carbon in the Strengthening of Silicon Crystals
Authors: Yonenaga Ichiro , Sumino Koji
Published: November 2005

Effect of substitutionally dissolved carbon on the mechanical strength of silicon crystals is investigated as a function of the concentration of oxygen dissolved in the crystals. It is concluded that carbon atoms increase the yield strength of silicon crystals when the crystals are initially dislocated and that these atoms coexist with oxygen atoms of concentrations higher than about 5×1017 atoms/cm3.
Optically Detected Magnetic Resonance in Fluorinated Amorphous Silicon (a-Si:F, a-Si:F, H and a-Si:F, D)
Authors: Yoshida Mihoko , Morigaki Kazuo , Matsumura Hideki
Published: November 2005

Optically detected magnetic resonance measurements were carried out at 2 K in a-Si:F, a-Si:F, H and a-Si:F, D. A correlation of A centres (trapped hole centres) with hydrogen is discussed as well as the importance of hydrogen for the luminescence fatigue.
Improved Uniformity of Resistivity Distribution in LEC Semi-Insulating GaAs Produced by Annealing
Authors: Obokata Takeshi , Matsumura Takao , Terashima Kazutaka , Orito Fumio , Kikuta Toshio , Fukuda Tsuguo
Published: November 2005

Two-dimensional distribution of resistivity in two-inch diameter crystals of LEC semi-insulating GaAs has been studied by the three-electrode guard method. Results are given in the form of a contour map for the wafers before and after annealing. Very significant fluctuations in resistivity on a 280 µm scale are observed for as-grown crystals, although the average of resistivity corresponds inversely to etch pit densities. The homogeneity of crystal grown at an 18 mm/h pulling rate, about two times faster than usual, is remarkably improved by annealing at 850°C for 20 minutes or longer.
Maskless Submicrometer Pattern Formation of Cr Films by Focused Sb Ion Implantation
Authors: Gamo Kenji , Moriizumi Koichi , Ochiai Yukinori , Takai Mikio , Namba Susumu , Shiokawa Takao , Minamisono Tadanori
Published: November 2005

Maskless submicrometer patterning of Cr films was done by implanting focused Sb+ ion and by plasma etching using CCl4 gas. Dose and depth dependence of the etching rate and Sb profiles were measured to investigate the concentration dependence of Sb. The present patterning characteristics are compared with conventional patterning characteristics using Au masks. It was found that a sharp threshold dose exists to form an etch resistant layer and this enables formation of few hundred nanometer thick, submicrometer patterns with vertical side walls. It was also found that the resistivity of patterned Cr films increase only 10%.
Dispersion Relation of Optical Eigen Modes in Chiral Smectic C by 4×4 Matrix Method
Authors: Ouchi Yukio , Shingu Toshiaki , Takezoe Hideo , Fukuda Atsuo , Kuze Eiichi , Koga Masao , Goto Nobuyuki
Published: November 2005

Dispersion relations of optical eigen modes (OEM's) in Sm C* are calculated by the 4×4 matrix method. The first order reflection region (full pitch band) consists of only a total reflection region. The structure of the second order reflection region, corresponding to that of the first order in cholesterics, strongly depends on the tilt angle of Sm C* and the propagation direction of OEM's. For a tilt angle smaller or larger than that of light propagation, the reflection region splits into three or consists of a single region with a structure.
Observation of Nonlinear Trajectories of Localized RF-Energy in an Inhomogeneous Magnetic Field
Authors: Ohnuma Toshiro
Published: November 2005

Nonlinear modifications of trajectories of localized RF-energy, so-called resonance cone fields, are observed in an inhomogeneous magnetic field when the applied RF energy is increased. The nonlinear shift of the RF-trajectories can be explained by nonlinear interaction between the localized RF-fields and plasma particles.
Observation of Ferroelectricity in Very Thin Vinylidene Fluoride Trifluoroethylene Copolymer[P(VDF·TrFE)] Films by High Frequency C-V Measurements of Al-SiO2-P(VDF·TrFE)-SiO2-Si Capacitors
Authors: Yamauchi Noriyoshi , Kato Kinya , Wada Tsutomu
Published: November 2005

MIS capacitors with Al–SiO2–P(VDF·TrFE)–SiO2–Si structure were fabricated depositing P(VDF·TrFE) film by a spin coating method to investigate properties of very thin ferroelectric polymer films. By sandwiching the polymer film with SiO2 films, application of an electrical field high enough for ferroelectricity measurement in several tens nm thick P(VDF·TrFE) films became possible. It is revealed that P(VDF·TrFE) film as thin as 32nm shows ferroelectricity by high frequency C-V measurements of the capacitors.
Electrostriction and Piezoelectricity in Ferroelectric Polymers
Authors: Furukawa Takeo , Wen Jian Xun
Published: November 2005

The effect of electrostriction on piezoelectric activity has been investigated in a ferroelectric copolymer of vinylidene fluoride and trifluoroethylene with a composition of 52/48 mol%. The electrostriction constants determined from changes in lattice spacing and the spontaneous polarization associated with a ferroelectric-to-paraelectric transition induce piezoelectric activities, positive d
31 and negative d
32. The combined contributions from the dimensional effect and the electrostrictire coupling are consistent with the magnitude and anisotropy of observed piezoelectric constants.
Fatigue and Recovery Effects of the 0.65-eV Emission Band in GaAs
Authors: Tajima Michio
Published: November 2005

The photoluminescence fatigue effect is carefully reinvestigated on a typical emission with a broad peak around 0.65 eV, believed to be associated with the main deep donor EL2, in undoped Czochralski-grown GaAs crystals. A characteristic recovery effect is found to occur in the “fatigued” emission band by continuous irradiation with Ar laser (514.5 nm); this is explained as an optical transition from the metastable state of the EL2 level to the conduction band in the configuration coordinate diagram. A wide variety of fatigue and recovery rates indicates that various lattice relaxations are induced by the microdefects responsible for the EL2 level.
Hole Transport in Glow-Discharge Produced a-Si:H:F Film
Authors: Nakayama Yoshikazu , Akiyama Koji , Haga Narita , Kawamura Takao
Published: November 2005

The transition in the hole transport at 351 K from dispersive to nondispersive has been observed using the time-of-flight technique on a-Si:H:F film lightly doped with boron, prepared by glow discharge in a gas mixture of SiF4, SiH4 and H2. The activation energy of the hole-drift mobility is 0.286 eV when the transport is nondispersive. The dispersion parameter has a large temperature dependence consistent with the multiple trapping transport. This film shows higher photoluminescence intensity than undoped and other boron doped films exhibiting the dispersive transport of holes over an examined temperature range.
New Selective Deposition Technology by Electron Beam Induced Surface Reaction
Authors: Matsui Shinji , Mori Katsumi
Published: November 2005

A new selective deposition technology by electron beam induced surface reaction has been demonstrated. Cr line patterns were deposited using Cr(C6H6)2 as a source. Cr deposition was confirmed by analysis using XMA and AES. The deposited thickness is proportional to electron beam dose. A 0.15 µm linewidth Cr pattern was deposited at 5×10-7 C/cm. This technology will be important for nanometer structure fabrication and new structure devices.
Annealing Effects in Heavily Ion-Implanted Magnetic Bubble Garnet Films
Authors: Imura Ryo , Ikeda Tadashi , Sugita Yutaka
Published: November 2005

Anomalous increase of the effective anisotropy field change Δ(H
K-4πM
S) has been found when magnetic bubble garnet films were heavily implanted with Ne+/He+ and subsequently annealed at high temperatures (350°C). With annealing, Δ(H
K-4πM
S) increases with annealing time, reaches a maximum value and then decreases. Δ(H
K-4πM
S) vs. strain (Δ
a/a) does not follow the curve for as-implanted films. Δ(H
K-4πM
S) has reached up to 3700 Oe which is 1200 Oe larger than that expected for as-implanted films (2500 Oe). This anomalous increase has been observed only for films whose initial strain is more than about 1.5%; the effect has not been observed in heavily H+
2 implanted films.
Temperature Distribution Measurement of Laser Produced Plasma by X-Ray Photodiode Array
Authors: Kasai Takeshi , Matsushima Isao , Ohwadano Yoshirou , Yano Masaaki
Published: November 2005

A multi-slit camera with an X-ray photodiode array has been developed to measure the electron temperature of a laser produced plasma. The fourth harmonic of Nd: glass laser output is irradiated on an aluminum plane target with a power density of 3×1014W/cm2. The camera is set to view the plasma side. The profiles of X-ray intensity are obtained immediately. Using Abel inversion, the spatially resolved electron temperature distribution with 300 eV at the center is calculated by the absorption method assuming the Maxwellian distribution of free electrons.
Kleinman Relation in the 3rd-Order Nonlinear Susceptibility of Dye Solutions
Authors: Saikan Seishiro
Published: November 2005

On the basis of orientation averaging of the 3rd-order nonlinear susceptibility, it is pointed out that Kleinman symmetry observed in most dye solutions arises from the axial property of π-π* transition dipole moment and its orientation averaging in isotropic media.
GaAs and GaAlAs Reactive Ion Etching in BCl3-Cl2 Mixture
Authors: Tamura Hideo , Kurihara Haruki
Published: November 2005

The reactive ion etching of GaAs and GaAlAs in BCl3–Cl2 mixture has been investigated. Under anisotropic etching conditions, clean etch profiles have been obtained with etch rates as high as 0.6 µm/min for GaAs and 0.4 µm/min for Ga0.55Al0.45As. No lag time has been observed between ignition of the gas plasma and subsequent etching. The variation in etch rates from run to run is less than±10%. The etch rates for the organic resist (AZ-1350) are so slow that deeply etched features (4–5 µm) with vertical side-walls have been obtained using a layer of the resist thin enough to maintain its high resolution.
0.67 µm Room-Temperature Operation of GaInAsP/AlGaAs Lasers on GaAs Prepared by LPE
Authors: Kishino Katsumi , Koizumi Yoshihiro , Yokochi Akira , Kinoshita Susumu , Tako Toshiharu
Published: November 2005

Room temperature pulsed operation of 0.67 µm wavelength GaInAsP/AlGaAs lasers on GaAs was achieved, where the lattice constant of GaInAsP active layer neraly matched those of the Al0.6Ga0.4As cladding layers. The threshold current density Jth of the device was 8 kA/cm2.
High Aluminum Composition AlGaInP Grown by Metalorganic Chemical Vapor Deposition –Impurity Doping and 590 nm (Orange) Electroluminescence–
Authors: Hino Isao , Kobayashi Kenichi , Suzuki Tohru
Published: November 2005

Improvement in doping characteristics and luminescence efficiency for MOCVD grown (Al
x
Ga1-x
)0.5In0.5P was obtained by introducing a simple air-lock system. A few hundredths Ωcm resistivity was obtained for the entire aluminum composition n-type (Al
x
Ga1-x
)0.5In0.5P and less than a few tenths Ωcm resistivity was obtained for p-type (Al
x
Ga1-x
)0.5In0.5P with x\lesssim0.6. 590 nm orange electroluminescence from double heterostructure diodes and 555 nm green photoluminescence, the shortest wavelengths ever-reported for (Al
x
Ga1-x
)0.5In0.5P system, were observed.
Observation of Lattice Defects in Single Crystals of Diacetylene (PTS) by X-Ray Topography
Authors: Kondo Minoru , Matsushita Mitsuyoshi , Izumi Kunihide , Ishizawa Akio
Published: November 2005

The defects in single crystals of diacetylene (PTS) are studied by X-ray topography (Lang's method). Three types of isolated dislocations are observed and two kinds of Burgers vectors are determined. The first is the dislocation with the Burgers vector [001] and the slip plane (100), which has the straight part, which is the pure edge part. The second is the dislocation with the Burgers vector [211]. The third is the dislocation which is perpendicular to (100). In addition, the bundle of pure screw dislocations with the Burgers vector [010] and the planar defect are observed.
A New Method for the Characterization of Traps in Luminescent Materials
Authors: Nakazawa Eiichiro
Published: November 2005

It is shown that measurements of the temperature dependence of the transient intensity of luminescence afterglow sampled at several points in time after the sudden stop of excitation serve as a reproducible and accurate experimental method to investigate traps in luminescent materials which can be superior to the prevailing thermo-luminescence method. An experimental result on Y2O2S activated by Eu3+ is presented as a practical example of this method.
Concentration Dependence of Fluorescence Lifetime of Nd3+-Doped Gd3Ga5O12 Lasers
Authors: Maeda Kazuo , Wada Naoki , Umino Masami , Abe Mitsuaki , Takada Yoichi , Nakano Noboru , Kuroda Hiroto
Published: November 2005

The Nd3+ concentration dependence of the fluorescence lifetime in laser crystal Gd3Ga5O12(GGG) for high power and high efficiency solid state laser is reported for the first time. The dominant mechanism of the concentration quenching in Nd3+: GGG rises from the electric dipole-dipole interaction between Nd3+ ions. The nonradiative transition probability of the 4F3/2 state is found to be proportional to the Nd3+ concentration squared up to the Nd3+ concentration of 5×1020 cm-3. The optimum Nd3+ concentration in Nd3+: GGG is estimated to be (3.4±0.5)×1020 cm-3 in pulsed laser operation.