bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation and Properties of Polycrystalline p-Type High-Conductivity CdTe Films by Coevaporation of CdTe and Te
Authors: Hayashi Toshiya , Hayashi Hiroaki , Mitsuru Fukaya Mitsuru Fukaya , Yoshinori Ema Yoshinori Ema
Published: February 2005

Polycrystalline p-type high-dark-conductivity CdTe films have been prepared by coevaporation of CdTe and Te. The structural and electrical properties were investigated. The dark conductivity of the films at 300 K ranged from 6.32×10-8 to 3.41 S cm-1. The film structure was of the zincblende type with a preferential orientation of the (111) planes parallel to the substrate. The crystallinity was rather good. From the measurements of the carrier concentration versus ambient temperature characteristics, it was found that the high-conductivity p-type conduction of the films was due to the formation of Cd vacancies, acceptors resulting from the coevaporation of CdTe and Te. It is shown that the high-conductivity films obtained are suitable for p-CdTe/n-CdS solar cells.
Bipolar-Complementary-Metal-Oxide-Semiconductor (BiCMOS) Technology with Polysilicon Self-Aligned Bipolar Devices
Authors: Kim Kwang Soo , An Kee Soo Nam
Published: February 2005

An advanced bipolar-complementary-metal-oxide-semiconductor (BiCMOS) technology providing uncompromised high-performance, double polysilicon self-aligned (PSA) n-p-n bipolar and 1.25 µm gate length CMOS transistors is described. The polysilicon self-aligned-BiCMOS technology (PSA-BiCMOS) is intended for high-speed logic circuit operation at 5 V, where a high level of circuit integration and power consumption is involved. Features include vertical n-p-n transistors with a self-aligned n+ polysilicon emitter and p+ polysilicon base. The CMOS transistor features n+ polysilicon gates and lightly doped drain (LDD) NMOSFET. A process simulator, Stanford University process engineering models (SUPREM III) and device simulator, Poisson and continuity equation solver (PISCES II) were used to optimize the process steps and to enhance device characteristics, respectively. The performance of N- and PMOS transistors is comparable to those of a conventional CMOS process. The driving capability of CMOS and PSA-BiCMOS was compared according to fan-out. Compared to CMOS, PSA-BiCMOS has good driving capability from about 2.5 fan-out and PSA-BiCMOS with 1.25 µm N- and PMOS transistors and a bipolar transistor with 2 µm emitter width exhibits an average ring oscillator delay of 6.25 ns/stage at 1 pF load capacitance at 5 V.
Superconductivity of YBa2Cu3O7-x by Addition of Reactive Fine Powders
Authors: Sakai Takenobu , Nishio Kozi , Ogawa Naoyuki , Izumi Hirabayashi Izumi Hirabayashi , Syoji Tanaka Syoji Tanaka
Published: February 2005

We report a new method for introducing pinning centers by partial melting processing using reactive fine powders, such as SiC, SiO2, Al2O3, and ZrO2. Since this method lowers processing temperature, it may become a useful technique for the production of high-J
c metal-sheathed tapes and wires. YBCO powders were mixed with 25 mol% SiC powder of 0.3 µm, sintered at 980°C for 15 min and cooled at 3°C/h under flowing oxygen gas. The obtained samples show prominent grain growth and reacted phases (Y2BaCuO5, Ba2SiO4) which are of submicron size and uniformly dispersed in the YBCO matrix. Magnetic measurements show the improvement of the critical currents (over 7500 A/cm2 at 77 K 0.04 T), and the sample shows the so-called fishing behavior at 77 K. It seems that the reacted phases (Y2BaCuO5, Ba2SiO4) work as effective pinning centers.
Confirmation of Aluminum-Induced Negative Charge in Native Silicon Dioxide
Authors: Munakata Hirofumi Shimizu
Published: February 2005

Ac surface photovoltage (SPV) disappears in p-type silicon (Si) wafers rinsed with an aluminum (Al)-contaminated RCA solution, while high ac SPV appears in n-type Si wafers. This is because large negative charge due to the metal impurity causes an accumulation region at the p-type wafer surface. The negative charge vanishes with the removal of the oxide. This means that Al resides in the native oxide.
Computer Simulation of Magnetization Reversal Mechanisms of Hexagonal Platelet Particle: Effect of Material Parameters
Authors: Nakatani Yoshinobu , Uesaka Nobuo Hayashi
Published: February 2005

The effect of material parameters on the switching mechanism and switching field, H
sw, of hexagonal platelet particles was investigated by computer simulation. The field H
E was applied perpendicular to the platelet plane which is the easy axis direction of the platelet. The magnetic moments of platelets with a small exchange stiffness constant, A, switch in the normal vortex mode; those of particles with a large A switch in the quasi-coherent rotation mode. The magnetic moments of platelets with a small uniaxial anisotropy constant, K
u, reverse in the normal vortex mode; platelets with a large K
u reverse in the crater mode. The magnetic moments of a thin platelet switch in the quasi-coherent rotation mode; a thick platelet switches in the normal vortex mode.
Porous Composite Slider Bearing Lubricated with Magnetic Fluid
Authors: M. V. Bhat M. V. Bhat , G. M. Deheri G. M. Deheri
Published: February 2005

A theoretical study of a porous composite slider bearing lubricated with magnetic fluid is made. Expressions for pressure, load capacity, friction, coefficient of friction and the centre of pressure are obtained. Magnetic fluid increases the load capacity, does not alter the friction, decreases the coefficient of friction and shifts the centre of pressure towards the inlet.
Total-Reflection Switch Using High-Tilt-Angle Cholesteric-Smectic C* Phase Transition Ferroelectric Liquid Crystal
Authors: Biradar Ashok Manikrao , Bawa Sukhwant Singh , Chhatra Pal Sharma Chhatra Pal Sharma , Subhas Chandra Subhas Chandra
Published: February 2005

A total internal reflection (TIR) microoptic switch using high-tilt-angle materials showing cholesteric-smectic C* phase transition for multimode fiber is described. The device shows excellent temperature-independent electrooptic characteristics and exploits the maximum contribution of ferroelectric liquid crystal (FLC) birefringence. The switch shows asymmetric response and unusual nonlinear behaviour, which is analysed by polarisation reversal current. The nonlinear response is due to the polar surface interaction which behaves as if it were positively charged and has been analysed by the transmission characteristics and by current analysis on applying square and triangular waves of various frequencies. The switch has a switching response of ∼20 ms limited due to monostable surface conditions, and shows a beam attenuation of ∼5×107 in the off state.
Study on Chemical Reactions on the Growing Surface to Control the Structures of µc-Silicon from Fluorinated Precursors
Authors: Nakata Masami , Sakai Akira , Shirai Hajime , Junichi Hanna Junichi Hanna , Isamu Shimizu Isamu Shimizu
Published: February 2005

We investigated the roles of atomic hydrogen in the crystal growth process from fluorinated precursors of SiH
n
F
m
under the two conditions that are dominated by the surface reaction on the substrate and by the gas phase reaction. Differences in structural morphology of microcrystal were observed by TEM (Transmission Electron Microscopy) measurement, and the dependence of crystal structure and orientation on growth thickness were compared. Furthermore, a slight amount of guest molecules modified the crystal structure effectively and improved the elliptic-shaped crystals in the case of PH3 doping gas without any post treatment. The shape of the elliptical crystal, especially the length of the longer axis of the crystal, was clearly changed according to the experimental conditions. This behavior appears as the key factor in elucidating the role of doping constituents of P.
On Ignition of Thermonuclear Fuels Using Neutron-Nuclei Fusion Reactions
Authors: K. Murukesapillai K. Murukesapillai
Published: February 2005

Ways to reduce the neutron number density required for the ignition of D-T fuel using exothermic neutron-nuclei fusion reactions have been investigated. It has been found that improvements in particle and energy confinement times by an order of magnitude reduces the minimum neutron number density required for ignition by an order of magnitude. For example, if the particle confinement time τp and the energy confinement time τE are equal and their values are 0.03, 0.3, 3, 30 seconds, the required minimum neutron number densities are 7.0×1021, 5.4×1020, 6.0×1019, and 6.0×1018 m-3, respectively. Methods to achieve these densities are also indicated.
Production of Electron-Free Plasma by Using a Magnetic Filter in Radio Frequency Discharge
Authors: Hiroshi Amemiya Hiroshi Amemiya
Published: February 2005

A source plasma is generated in a multipole-type device in oxygen by a radio frequency discharge at 13.56 MHz. A SmCo magnet array is mounted between source and target plasma sections as a magnetic filter. In the target section, almost electron-free plasma is obtained. The device can be operated in the pressure range of 10-3 to 10-1 Torr. The plasma densities in source and target plasmas are 109-1010 cm-3 and 108-109 cm-3, respectively.
A New Capacitive / Resistive Probe Method for Studying Magnetic Surfaces
Authors: Kitajima Sumio , Takayama Masakazu , Zama Tatsuya , Takaya Kazuhiro , Takeuchi Nobunao , Hiroshige Watanabe Hiroshige Watanabe
Published: February 2005

A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced.
Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines.
Structure-Parameter Dependence of Modality of Macroscopic Quantum Effect in Superconductor Junction (II) –Linked Junction–
Authors: Masanori Sugahara Masanori Sugahara , Nobuyuki Yoshikawa Nobuyuki Yoshikawa
Published: February 2005

Quantum behaviors of linked junctions of superconductor and normal metal are theoretically studied with the following results. They are classified into two types: type 1 with normal conductance G>G
c and type 2 with G<G
c, where G
c is the critical conductance. Ideal models of type 1 and type 2 are, respectively, prescribed with a set of parameters (g
p≫1, g
s=1) and (g
p=1, g
s≫1), where g
p (parallel mode number) is the number of electronic quantum modes over the cross section of the link and g
s (series mode number) is the number of loss oscillators (phonons or photons) which perform energy-exchange interaction with a transitting electron. In the case of superconductor junctions, type 1 shows the Josephson effect and type 2 shows the PQT effect (duality of Josephson effect). The PQT effect is also expected in some normal type 2 junctions.
Construction of Retarding Field Cylindrical Mirror Analyzer
Authors: Sohma Makoto , Kurokawa Akira , Sakai Ryuichi Shimizu
Published: February 2005

A retarding field cylindrical mirror analyzer (RF-CMA) was constructed. Particular attention was paid to setting up two hemispherical grid-meshes which provide the concentrical retarding field. The grid-meshes were prepared by photoetching and formed by cold working. Mesh holders were made by discharge machining with accuracy of less than several microns.
The performance was examined by measuring elastic peaks and Ag-MVV Auger spectra for different retarding voltages. The result has confirmed that the present RF-CMA allows measurement of the spectrum with resolution twice as high as the conventional CMA without any decrease in the peak intensity of the signals. For higher retarding field, the energy resolution becomes higher as expected while the peak intensity gradually decreases, probably due to the distortion in the concentrical retarding field.
Measurement of Beam Bunch Length in the 1.3-GeV Electron Synchrotron
Authors: Mutou Masayuki , Maruyama Koichi , Fukushima Toshitaka , Miyahara Yoshikazu , Katsuhide Yoshida Katsuhide Yoshida
Published: February 2005

We observed the bunch structure of the circulating beam in the 1.3-GeV Electron Synchrotron (ES) for the first time. The ES operated at a repetition rate of 21 Hz and an rf frequency of 138 MHz. The bunch length variation during the rf acceleration was determined by measuring time distributions of photons produced by the synchrotron radiation. The observed lengths show a rapid decrease from 1.83 to 0.72 ns (FWHM) in the 2-5 ms time interval after the start of acceleration (energy range 0.1-0.25 GeV), and they are almost constant, 0.6-0.7 ns, by the end of acceleration (0.25-1.1 GeV). The behavior is well reproduced by a calculation taking into account the effects of the adiabatic damping, radiation damping, and radiation excitation.
Formation of Titanium Nitride/Titanium Silicide by High Pressure Nitridation in Titanium/Silicon
Authors: Chen Shih-Chang , Tamura Hiroyuki , Hara Tohru , Inoue Ken , Endo Nobuyuki , Kinoshita Kei , Nakamura Shigeaki
Published: February 2005

Formation of a titanium nitride (TiN) layer by the nitridation of Ti in high-pressure (5.8 atm) ammonium (NH3) ambient is studied. A thick TiN layer is formed in high-pressure nitridation. Solid-phase silicidation reaction occurs at Ti/Si during the nitridation. When a thin Ti layer is nitrided in high-pressure NH3 for instance, a thicker TiN and thin TiSi2 multilayer structure, TiN(250 Å)/TiSi2(350 Å)/Si is formed. This structure is useful as a barrier metal for Al ohmic contact and for the adhesion layer in blanket tungsten.
Effects of Phosphorus Pressure on Low-Energy Emission Bands in Zn-Diffused InP
Authors: Wada Morio , Katsutoshi Sakakibara Katsutoshi Sakakibara , Yoichi Sekiguchi Yoichi Sekiguchi
Published: February 2005

The effects of phosphorus pressure during Zn diffusion and sequential annealing on the diffusion profiles and the photoluminescence spectra were investigated by secondary ion mass spectrometry (SIMS) analysis, capacitance-voltage (C-V) and photoluminescence (PL) measurements. Zn diffusion was performed using dimethylzinc as the Zn source. We found that as the PH3 flow rate increased, the diffusion depth deepened and a low-energy broad emission band at 1.23-1.32 eV (77 K) from near the Zn-diffused surface shifted to higher energy while its intensity increased. Another low-energy emission band at 1.28-1.33 eV (77 K) was observed in the Zn-diffused InP with high Zn interstitial concentration. The excitation and temperature dependences of the peak energies indicate that these bands are the so-called quasi-donor-acceptor pair bands with lattice relaxation. These results, along with the effect of annealing, suggest that a Zn incorporation mechanism with a contribution from phosphorus-related defects occurs near the surface.
High-Performance a-SiGe Solar Cells Using a Super Chamber Method
Authors: Haku Hisao , Sayama Katsunobu , Maruyama Eiji , Dohjoh Hiroshi , Nakamura Noboru , Tsuda Shinya , Nakano Shoichi , Yasuo Kishi Yasuo Kishi , Yukinori Kuwano Yukinori Kuwano
Published: February 2005

The influence of impurities on the a-SiGe film properties was investigated using a super chamber. It was found that a-SiGe films with a low impurity concentration can maintain a high photosensitivity of about 106 for Ge content up to 13%, and impurity incorporation deteriorates film rigidity, which was first deduced from the STM (scanning tunneling microscope) measurement. Using a super chamber method, the highest conversion efficiency of 3.34% was obtained for an a-SiGe single-junction cell under red light (long-wavelength light (>∼650 nm) by filtering AM-1.5, 100 mW/cm2 light). A conversion efficiency of 11.9% was also achieved for a stacked cell of a-Si/a-Si/a-SiGe.
Growth and Properties of ZnSe Crystals by a Modified Bridgman Method
Authors: Kikuma Isao , Masatoshi Matsuo Masatoshi Matsuo , Toyokazu Komuro Toyokazu Komuro
Published: February 2005

Zinc selenide crystals are grown from the melt by a modified Bridgman method under argon pressure. The electrical and optical properties of the as-grown crystals are measured as a function of the temperature of a Zn reservoir which produces a vapor of a specific Zn partial pressure. Low-resistivity n-type crystals of 0.2 to 2 Ω·cm are grown at the temperature of the Zn reservoir above 960°C. Electron Hall mobility of the crystals decreases with increasing temperature of the Zn reservoir during growth. A mobility value of 550 cm2/V·s is obtained at room temperature (290 K). The extra Zn partial pressure enhances a bound-exciton line and suppresses deep-level emission bands around 500 and 600 nm in photoluminescence spectra at 10 K.
Hg1-xCdxTe Surface after Chemical Etching and Electrochemical Reduction
Authors: Kengo Shimanoe Kengo Shimanoe , Masao Sakashita Masao Sakashita
Published: February 2005

Surface compositions of Hg1-x
Cd
x
Te (MCT) after chemical etching and electrochemical reduction have been studied with an angle-dependent X-ray photoelectron spectroscopy (XPS) technique. The degree of oxidation formed after the chemical etching in Br2-methanol solutions is dependent on Br2 concentration but independent of etching time. The etched surface is Te-rich. The cation fraction x deviates from that of the bulk value. The oxides and accumulated elemental Te are eliminated from the etched surface by the reduction at -0.9 V vs Ag/AgCl for 1 h in pH 5.0 acetic-acetate solution. The cation/anion ratio and cation fraction x approach the bulk value and are constant in the depth. Furthermore, it is confirmed that the electrochemically reduced surface is more stable in atmospheric oxygen than the chemically etched MCT. This electrochemical reduction is used for treatment prior to surface passivation.
The Field Effect Mobility and the Current-Voltage Characteristics of Amorphous-Silicon Thin-Film Transistors
Authors: Miki Hidejiro , Tobita Toshio , Tsunehiko Nakanishi Tsunehiko Nakanishi , Komyo Kariya Komyo Kariya
Published: February 2005

The current-voltage characteristics of a hydrogenated amorphous silicon thin-film transistor were investigated. The computed equation for the current-voltage characteristics that incorporated gate-voltage-dependent field effect mobility and drain-voltage-dependent effective gate length was in excellent agreement with the experimental data.
p-Type a-SiC:H Films Using Triethylboron and Its Application to Solar Cells
Authors: Tabuchi Katsuya , Yamada Akira , Takahashi Makoto Konagai
Published: February 2005

We propose a new p-type doping gas, B(C2H5)3, instead of the conventional B2H6 gas, which has no B-B bond and B-H bond. The photo- and dark conductivities of 6.0×10-6 Scm-1 and 1.4×10-6 Scm-1 were obtained at the optical band gap of 1.98 eV using B(C2H5)3 and these values are comparable to those of films using B2H6. The conversion efficiency of 11.3% was obtained by applying the p-type a-SiC:H films using B(C2H5)3.
Magnetic Field Dependence of Critical Current Density of Polycrystalline Tl-2223 Wire
Authors: Okada* Michiya , Nabatame Toshihide , Yuasa Toyotaka , Aihara Katsuzo , Seido Masahiro , Shinpei Matsuda Shinpei Matsuda
Published: February 2005

The magnetic field dependence of critical current density J
c for polycrystalline Tl-2223 tape-shaped wire was examined in terms of a model regarding a sample as a bulk which consists of an anisotropic superconductor with an incomplete crystal alignment. We assumed that the critical current density in each grain would be governed only by the perpendicular component of magnetic field to the a-b plane, especially in a high magnetic field. In a low field, we also assumed that the grain boundary weak link would be dominant in terms of J
c. It was found that the magnetic field dependency of J
c in high fields was well described by the present calculation in spite of an inconsistency in low magnetic fields. It was predicted that a practical J
c value of more than 10,000 A/cm2 in a magnetic field above 5T might be possible with a crystal alignment factor of standard deviation σ below 0.5, assuming the crystal alignment in the wire to be of Gaussian distribution.
Structure and Soft Magnetic Properties of Fe/CoZr Multilayer Films
Authors: Jimbo Mutsuko , Sobue Eiji , Shigeru Tsunashima Shigeru Tsunashima , Susumu Uchiyama Susumu Uchiyama
Published: February 2005

Fe/CoZr multilayer films prepared by the RF magnetron sputtering method are reported. The films have a bcc structure with the (110) preferred orientation and consist of fine crystallites of about 10 nm in diameter. The growth of crystallites is very gradual below 350°C. Even after annealing at 450°C, the grain growth is unremarkable, and compositionally modulated structure still remains. The films show excellent soft magnetic properties after annealing above 400°C. Typical values of saturation magnetization, coercive force and saturation magnetostriction were about 21 kG, 1.8 Oe, and +2×10-5, respectively. The films also show a high permeability of about 1800 at frequencies up to 100 MHz.
Static and Dynamic Characteristics of Metalorganic-Vapor- Phase-Epitaxy-Grown 1585 nm InGaAs/InGaAlAs Separate Confinement Heterostructure Multiple-Quantum-Well Metal-Clad Ridge-Waveguide Lasers
Authors: Stegmüller Bernhard , Borchert Bernd , Hedrich Harald , Hans Lang Hans Lang , Gabriele Asam Gabriele Asam
Published: February 2005

Fabrication and characteristics of InGaAs/InGaAlAs separate confinement heterostructure multiquantum-well (SCH-MOW) metal-clad ridge-waveguide (MCRW) laser diodes are reported. The layer structures have been grown by atmospheric pressure metalorganic vapor phase epitaxy (AP-MOVPE) without any use of phospine.
The lasers emit around 1585 nm, and the minimum cw-threshold current is 15 mA for 200 µm-long lasers with high-reflection (HR) coating on both mirrors. For 600 µm- and 800 µm-long one-side HR-coated devices, continuous wave (CW) output power levels up to 16 mW and CW operation around 60°C have been achieved. A power-limited 3 dB bandwidth of 5.1 GHz has been measured. From small signal modulation measurements, a maximum differential gain of 7.7×10-16 cm2 has been calculated.
Molecular Luminescence from Electron-Bombarded YBa2Cu3O7-x
Authors: Masao Kamada Masao Kamada , Sayumi Hirose Sayumi Hirose
Published: February 2005

Luminescence from electron-bombarded YBa2Cu3O7-x
was investigated. It has been found that the luminescence is similar in shape and energy position to the vibronic luminescence due to the CN- molecule, indicating that the luminescence is attributed to the CN- adsorbed on the YBa2Cu3O7-x
surface but not to the luminescence of intrinsic origin.
Time-Resolved Luminescence from (La, Ce)PO4:Tb Phosphors
Authors: Ibuki Sumiaki , Noguchi Toru , Tomoaki Hatayama Tomoaki Hatayama , Shigeru Fukumoto Shigeru Fukumoto
Published: February 2005

Time-resolved spectra of Tb3+ emission have been investigated for highly Tb doped LaPO4 phosphors under 365 nm excitation and 5D3 emissions of Tb3+ at which decay constants much faster than that of 5D4 were observed. Further new line emissions at around 600 nm were found in (La, Ce, Th)(PO4,BO3):Tb phosphor under 365 nm dye laser excitation. The mechanisms for the emissions were discussed, and it is considered that the emissions originated from Ce2+ as a result of the spectral structure and the decay time.
Silver- and Gold-Related Deep Levels in Gallium Arsenide
Authors: Pandian Velayuthan , Yashowanta N. Mohapatra Yashowanta N. Mohapatra , Vikram Kumar Vikram Kumar
Published: February 2005

Characterization of silver- and gold-related defects in gallium arsenide is carried out. These impurities were introduced during the thermal diffusion process and the related defects are characterized by deep-level transient spectroscopy and photoluminescence. The silver-related center in GaAs shows a 0.238 eV photoluminescence line corresponding to no-phonon transition, whereas its thermal ionization energy is found to be 0.426 eV. The thermal activation energy of the gold-related center in GaAs is 0.395 eV, but there is no corresponding luminescence signal.
A Method for the Determination of the Internal Electric Field of Ion-Doped Ferroelectric Liquid Crystals
Authors: Ono Katsumichi , Nakanowatari Jun
Published: February 2005

A new experimental method for the determination of the internal electric field in surface-stabilized ferroelectric crystal cells was proposed. The method is based on the simultaneous analysis of the current responses against square and triangular wave imposition of the voltage across the cell. From this method, the rotational viscosity coefficient and the ionic mobility of a ferroelectric liquid crystal doped with tetra-cyanoquinodimethane (TCNQ) can be estimated. Furthermore, two internal field components, i.e., the internal field due to depolarization and that due to ionic space charge, were calculated.
The Microstructure of ZnO Varistor Doped with Antimony Oxide
Authors: Wu Long , Shen Chi-Yen , Chen Ying-Chung , Wei Yin-Fang , Mao-Hsiung Chen Mao-Hsiung Chen , Kuang-Chih Huang Kuang-Chih Huang
Published: February 2005

The effects produced by different valency and amount of antimony ions on the resulting microstructures of ZnO varistors were studied. From the observation of scanning electron microscopy (SEM), the composition originally added with high valency of antimony ion had a larger grain size than that originally added with a low valency of antimony ion. Conversely, the composition originally added with a high valency of antimony ion possessed fewer intragrain particles than that originally added with a low valency of antimony ion. The spinel particle size and number of intragrain particles increased when the sintering temperature was raised. The compositions containing more antimony oxide can form more spinel phases, and result in an increase in grain growth kinetic exponent and activation energy as well as a decrease in grain size. These compositions have fewer intragrain particles and more spinel particles than those containing less antimony oxide.
Deposition of SiO2 Films from ArF Laser Photolysis of SiH4/N2O Mixtures
Authors: Tsuji Masaharu , Naoki Itoh Naoki Itoh , Yukio Nishimura Yukio Nishimura
Published: February 2005

Deposition of SiO2 thin films by the ArF excimer laser photolysis of mixtures of SiH4 and N2O has been studied in the low substrate temperature range of 30-400°C. The structural properties of the oxide layers were studied by FT-IR spectroscopy. The refractive index of films agreed with that of stoichiometric SiO2 in the substrate temperature range of 150-400°C. The deposition conditions were studied as a function of the substrate temperature, the deposition time, the laser repetition rate, the total pressure, and the N2O/SiH4 flow ratio. The maximum growth rate was ∼70 Å/min at a substrate temperature of 400°C, a total pressure of 2 Torr, a repetition rate of 50 Hz, and a N2O/SiH4 flow ratio of ∼800.
Observation and Analysis of the Δv=5 Stretch Overtone Band Transition of 15NH3
Authors: Moriwaki Yoshiki , Ken'ichi Nakagawa Ken'ichi Nakagawa , Tadao Shimizu Tadao Shimizu
Published: February 2005

The absorption spectra of the Δv=5 stretch overtone band transition of 15NH3 in the visible region (648 nm band) are observed by the photoacoustic method for the first time. The resolution is 0.01 cm-1. The observed Stark spectra at electric field high enough to resolve M components are helpfully employed in assignment of the rotation and inversion transitions. The vibrational level structure is well explained in terms of the local mode theory. The rotational constants and isotope shift are obtained.
Electron-Impact Dissociation of Methane into CH3 and CH2 Radicals II. Absolute Cross Sections
Authors: Nakano Tohru , Hirotaka Toyoda Hirotaka Toyoda , Hideo Sugai Hideo Sugai
Published: February 2005

The electron energy dependence of partial cross sections for dissociation of methane into CH3 and CH2 radicals has been reported in part I of this paper. In order to assign absolute values to these relative cross sections, two additional experiments were carried out. One was cross-section measurement for electron-impact nitrogen dissociation (N2→N+N, N+N+) using threshold-ionization mass spectrometry. The other was the measurement of sticking coefficients of CH3, CH2, and atomic nitrogen. According to these measurements, the absolute partial cross sections for neutral dissociation were determined: maximum cross section is 1.4×10-20 m2 at 24 eV for CH3 radical and 0.72×10-20 m2 at 18 eV for CH2 radical.
Control System of RIKEN Heavy Ion Accelerator Complex
Authors: Wada Takeshi , Kambara Tadashi , Yokoyama Ichiro , Shimizu Kazuo , Takebe Hideki , Makoto Nagase Makoto Nagase , Hiromichi Kamitsubo Hiromichi Kamitsubo
Published: February 2005

The RIKEN heavy ion accelerator complex is controlled by means of three minicomputers, which are linked with one another through optical fiber networks. CAMAC serial highway and GP-IB are used for the link with accelerator devices. Two types of intelligent modules are developed for the interface to devices; one is a CAMAC module and the other is a control module for high-speed local control of the accelerator devices. The operating system is a combination of a real-time and a UNIX system. Application programs are written in FORTRAN 77 language. A color display-based operator's console is adopted with the aim of simple operation and flexibility for future modification and expansion.
Imaging Characteristics of Multi-Phase-Shifting and Halftone Phase-Shifting Masks
Authors: Terasawa Tsuneo , Hasegawa Norio , Hiroshi Fukuda Hiroshi Fukuda , Souichi Katagiri Souichi Katagiri
Published: February 2005

Phase-shifting masks and imaging characteristics are discussed and compared with those of conventional transmission masks. Then, new phase-shifting masks with intermediate values of phase shifting or transmittance are proposed, and their imaging characteristics are investigated. A phase-shifting mask with a 90° phase difference can ease the restrictions on pattern geometries used in phase-shifting technology but does not increase the focus latitude. It is also suggested that a halftone phase-shifting mask is suitable for printing isolated patterns and it gives wider focus latitude than conventional mask technology.
Development of Highly Stable Synchrotron Radiation Source at SORTEC
Authors: Kodaira Masanobu , Awaji Naoki , Kishimoto Takeshi , Hiroshi Usami Hiroshi Usami , Makio Watanabe Makio Watanabe
Published: February 2005

The construction and the initial beam conditioning of a 1-GeV synchrotron radiation (SR) source facility at SORTEC Corporation were successfully completed in 1989. The regular operation for lithography experiments was started in April 1990, and highly stable operation has been maintained for over one year. At present, the beam lifetime with the stored beam of 200 mA has reached over 50 hours. Due to stable beam refilling into the storage ring, automatic operation for a constant level control of the stored beam current was also successfully confirmed. In this paper, performance of the SR source will be further discussed from the viewpoint of the industrial use of the SR source for X-ray lithography in terms of stable and flexible operation, operation efficiency, utilities and radiation safety.
Optical Design for Soft X-Ray Projection Lithography
Authors: Watanabe Yutaka , Suzuki Masayuki , Mochizuki Noritaka , Masahito Niibe Masahito Niibe , Yasuaki Fukuda Yasuaki Fukuda
Published: February 2005

We investigated the effect of soft X-ray multilayer mirrors on the characteristics of image formation and determined that the phase shift of the X-ray on the mirror plays an important role in image formation as well as reflectivity. Under such a condition that the effect on the characteristics of image formation can be neglected, we designed an optical system that has a resolution of 0.18 µm and 0.25 µm at the wavelength of 5 nm and 13 nm, respectively, and distortion of less than 0.01 µm in a whole exposure field of 20×40 mm2. The necessary surface accuracy of mirrors and tolerance of setting mirrors are discussed.
Precise Reactive Ion Etching of Ta Absorber on X-Ray Masks
Authors: Masafumi Nakaishi Masafumi Nakaishi , Kenji Sugishima Kenji Sugishima
Published: February 2005

We investigated the reactive ion etching (RIE) of the Ta absorber on X-ray masks using a mixture of chlorine (Cl2) and chloroform (CHCl3) gases. To improve the pattern profiles, we used a gas mixture of chlorine (Cl2) and chloroform (CHCl3) which enhances deposition and protects side wall. We consistently obtained vertical side walls (90°±3°) with a Ta-to-resist etch-rate ratio (selectivity) of 7 and pattern edge roughness below 0.02 µm. The transfer accuracy was 0.00±0.04 µm (3 sigma) using 40% CHCl3 and Cl2 with a gas pressure of 0.2 Torr and power density of 0.8 W/cm2.
Time-Resolved Photoluminescence Spectra in Single Crystals of CuAlS2:Mn
Authors: Sato Katsuaki , Ishii Koki , Kunio Watanabe Kunio Watanabe , Kensei Ohe Kensei Ohe
Published: February 2005

Time-resolved spectra were measured in single crystals of CuAlS2 doped with different concentrations of Mn, as well as in an undoped crystal, to elucidate the recombination mechanisms associated with the red photoluminescence band at 1.96 eV. The 0.01 wt% Mn-doped sample shows a broad emission band around 2.5 eV, 25 ns after the excitation, which loses intensity rapidly, transferring energy to an infrared peak. At 10 µs both bands are quenched, leaving the red band at 1.96 eV. On the other hand, the PL spectrum in 1 wt% Mn-doped samples at 25 ns consisted of a purple peak at 3 eV and a red peak at 1.96 eV. The purple PL peak relaxed rapidly with a decay time of 50 ns, while the red peak showed a slow decay with a time constant of 100 µs. The possibility of energy transfer between the host impurity/defect states and the Mn ion is discussed.
Smoothing Roughness of SiC Membrane Surface for X-Ray Masks
Authors: Yamashiro Kazuhide , Sugawara Minoru , Hiroyuki Nagasawa Hiroyuki Nagasawa , Yoh-ichi Yamaguchi Yoh-ichi Yamaguchi
Published: February 2005

We have obtained a smoother surface of SiC membranes than that of as-deposited SiC using etch-back and polishing methods, and investigated the influence of surface roughness of SiC films on internal stress and film structure of X-ray absorber films and optical transmittance of SiC membrane. Surface roughness for the as-deposited SiC surface is 15 nm (Ra), whereas that for etch-backed SiC is 6.9 nm (Ra) and that for polished SiC is 4.3 nm (Ra). Optical transmittance of as-deposited SiC membrane is 48% (λ=633 nm) and increases by a few percent with decrease in the Ra value. Internal stress of sputtered Ta tends to show gentler change with increasing surface roughness of SiC film. Film structure of Ta film is largely influenced by the surface roughness of SiC films at low Ar pressure. Sub-half micron absorber patterns with vertical walls, however, have been obtained even on rough surface SiC.
High Performance Resists Tailored for 248 nm Chemical Amplification of Resist Lines Technology
Authors: Sezi Recai , Borndörfer Horst , Leuschner Rainer , Nölscher Christoph , Sebald Michael , Hellmut Ahne Hellmut Ahne , Siegfried Birkle Siegfried Birkle
Published: February 2005

Different dry developable resist systems operating in positive bilayer (Si-CARL) and negative top surface imaging (Top-CARL) modes were investigated for application in 248 nm lithography. After exposure with the KrF excimer laser projection aligner (NA=0.37), development, aqueous silylation and oxygen reactive ion etching, 0.25 µm structures were obtained as the ultimate resolution of Si-CARL with a topresist containing diazoketone photoactive compounds. The process latitudes for 0.4 µm and 0.5 µm lines and spaces amount to 25% and 30% for exposure and to 3 µm and 3.2 µm for defocus, respectively. Comparable values were determined for an alternative Si-CARL system with a new acid catalysed topresist. The required doses for zero bias exposure are 65-70 mJ/cm2 (diazoketone) and 21 mJ/cm2 (acid catalysed). The Top-CARL resist also utilizes the acid catalysed deprotection chemistry for selective silylation of the exposed areas. The preliminary formulation presented well-shaped 0.35 µm structures at 10 mJ/cm2.
Chemically Amplified Bilevel Resist Based on Condensation of Siloxanes
Authors: Sakata Miwa , Toshio Ito Toshio Ito , Yoshio Yamashita Yoshio Yamashita
Published: February 2005

This paper deals with a negative bilevel resist which is based on the acid-catalyzed condensation reaction of poly(siloxane)s. The resist systems consist of photoacid generators and poly(siloxane). Ph3S+OTf- reveals an efficient activity for silanol condensation and the system has a high sensitivity of 0.31 mJ/cm2. Tetrafunctional silane plays the role of crosslinker in this system. Sensitivity improvement of low-sensitivity systems such as benzoin p-toluenesulfonate/poly(siloxane) can be achieved by this method.
Prebake Effects in Chemical Amplification Electron-Beam Resist
Authors: Azuma Tsukasa , Masui Kenji , Takigami Yuji , Sasaki Hideyuki , Sakai Kimihito , Nomaki Tatsuo , Yoshihide Kato Yoshihide Kato , Ichiro Mori Ichiro Mori
Published: February 2005

Prebake effects in chemical amplification electron-beam resist SAL601-ER7 have been investigated. Resolution of the resist is found to be greatly dependent on the prebake conditions when a thick resist film is used. The results of FT-IR and GC/MS analysis suggest that differences in the resolution between thin and thick resist films are due to the residual solvent content which depends on prebake temperature. Because the residual solvent in the resist film is thought to act as a kind of reaction medium, it can be concluded that it affects the diffusion length of the acid catalyst.
Effects of Substrate Temperature during Phosphor Layer Deposition on Luminance of SrS:Ce Blue-Green-Emitting Thin-Film Electroluminescent Devices
Authors: Onisawa Ken-ichi , Abe Yoshio , Takahiro Nakayama Takahiro Nakayama , Masanobu Hanazono Masanobu Hanazono
Published: February 2005

In order to improve the luminance of blue-green-emitting SrS:Ce thin-film electroluminescent devices, the effects of substrate temperature (350-550°C) during phosphor layer deposition were studied. Two deposition procedures were used: sulfur coevaporation and sulfurization of evaporation sources. The luminance increased with increasing substrate temperature in both cases. As the substrate temperature increased, oxygen content decreased and sulfur content remained almost constant for coevaporation; however, sulfur content increased while oxygen content remained low when the sulfurization technique was used. These changes led to improvement in the crystallinity of the phosphor layers. Also, sulfur and oxygen contents in phosphor layers deposited at 550°C by both procedures were almost the same, and as a result, the luminance levels were almost the same.
High Performance Electron Cyclotron Resonance Plasma Etching with Control of Magnetic Field Gradient
Authors: Fujiwara Nobuo , Sawai Hisaharu , Yoneda Masahiro , Nishioka Kyusaku , Horie Kazuo , Kazuo Nakamoto Kazuo Nakamoto , Haruhiko Abe Haruhiko Abe
Published: February 2005

It is shown that high-performance Electron Cyclotron Resonance (ECR) plasma (hyper-ECR) is effective as a dry etching technique for fabrication of VLSI devices. The gradient of the magnetic field is one of the most important parameters for a uniform high etch rate. The Si etch rate and the ion current density can rise with decreasing magnetic field gradient. The high uniformity of the etch rate is achieved with highly uniform distribution of the magnetic field gradient. The density distribution of plasma is also improved by the hyper-ECR, so the drift instability is stabilized and a no-microloading etching process is produced.
Compact Electron Cyclotron Resonance Plasma-Etching Reactor Employing Permanent Magnet
Authors: Narai Akira , Hashimoto Tetsuro , Ichihashi Hideki , Haruo Shindo Haruo Shindo , Yasuhiro Horiike Yasuhiro Horiike
Published: February 2005

A compact electron cyclotron resonance (ECR) plasma-etching reactor employing Sm-Co magnets was studied. A flattened rectangular waveguide with a slot antenna enabled this ECR system, and the plasma was generated with high density of 2×1012 cm-3 at 1×10-3 Torr of Ar. The silicon etch rate in NF3 was limited at low-gas flow rate because of the redeposition of the etching products dissociated by high-density plasma; but, by increasing flow rate, 5000 Å/min was achieved at 1×10-3 Torr under the floating potential of 15 eV. The RF bias of 100 W (430 V of the self-bias) offered a very high etch rate of 2.3 µm/min. The directional feature was achieved at 25 W RF bias (180 V of the self-bias) at 5×10-4 Torr. Further, the multi-slot antenna which was excited by independent microwave sources turned out to improve the etching uniformity considerably.
Electrooptic Light Modulation in Poled Azo-Dye-Substituted Polymer Waveguides
Authors: Shuto Yoshito , Michiyuki Amano Michiyuki Amano , Toshikuni Kaino Toshikuni Kaino
Published: February 2005

The DC electrooptic modulation of 0.633-µm He-Ne laser light has been measured in thin-film waveguides of copolymers containing Disperse Red-1 (DR1) and/or novel dis-azo-dye side chains. The polarized laser light is butt-coupled to the polymer waveguides with propagation length of 4 mm and film thickness of 10-15 µm. The DC linear electrooptic coefficients r33 of the poled DR1- and dis-azo-dye-substituted polymer films are estimated to be 18 pm/V and 27 pm/V at 0.633 µm. Comparison with second-harmonic generation results demonstrates that the DC linear electrooptic effect in the poled azo-dye-substituted polymers is primarily electronic in nature.
Fabrication and Luminescence of Narrow Reactive Ion Etched In1-xGaxAs/InP and GaAs/Gas1-xAlxAs Quantum Wires
Authors: Izrael A. , Marzin J. Y. , Sermage B. , Birotheau L. , Robein D. , Azoulay R. , Benchimol J. L. , Henry L. , Thierry-mieg V. , Ladan F. R. , Taylor L.
Published: February 2005

We present the fabrication process of narrow quantum wires in both In1-x
Ga
x
As/InP and GaAs/Ga1-x
Al
x
As systems based upon e-beam lithography, lift-off, reactive ion etching and MOCVD overgrowth. The carrier lifetime, deduced from low temperature time-resolved photoluminescence, remains of the order of one nanosecond in both systems, showing the good quality of the overgrown interfaces. An efficient capture of the carriers created in the barrier material into the wires is demonstrated. One-dimension quantum confinement effects are observed for the lowest lateral sizes: in In1-x
Ga
x
As/InP wires (width down to 15 nm), quantum shifts of the low temperature cw photoluminescence peak (up to 30 meV) are observed while in GaAs/Ga1-x
Al
x
As wires (width down to 20 nm), we report shifts up to 10 meV of the emission peak.
Ten-Nanometer Resolution Nanolithography using Newly Developed 50-kV Electron Beam Direct Writing System
Authors: Ochiai Yukinori , Baba Masakazu , Heiji Watanabe Heiji Watanabe , Shinji Matsui Shinji Matsui
Published: February 2005

A high energy 50-kV electron beam direct writing system which has a gas introduction line has been developed. Several aspects of the performance of this system are demonstrated. The electron beam size has been improved to be less than 5 nm. 10-nm width line patterns with 50-nm periods in PMMA resist on a thick Si substrate are demonstrated. It is observed that fewer proximity effects occur when a high-energy electron beam is used. 20-nm-width lines and 20-nm-diameter Au-Pd metal patterns have been fabricated by a lift-off method. 14-nm-diameter carbon dot patterns were deposited on a Si substrate by electron-beam-induced deposition using Styrene gas.
Effect of Water Vapor on the Growth of Textured ZnO-Based Films for Solar Cells by DC-Magnetron Sputtering
Authors: Nakada Tokio , Yukinobu Ohkubo Yukinobu Ohkubo , Akio Kunioka Akio Kunioka
Published: February 2005

Large-grain zinc oxide (ZnO) films have been deposited on glass substrates by DC magnetron sputtering in H2O-Ar mixtures at elevated substrate temperatures. The (002)-oriented columnar structure grown in pure Ar changed into the granular structure as the partial pressure of water vapor increased. Low-resistivity pyramidal textured ZnO:Al films were sputter-deposited in a mixture of H2O-Ar(1:1) at 300-400°C. The 2-µm-thick films possessed a sheet resistance of 9 Ω/□ and optical transmission of 80% at 550 nm after annealing in a vacuum. These films have considerable potential as window materials for solar cells.
Relationship between Molecular Orientation and Optical Memory Angle of Surface-Stabilized Ferroelectric Liquid Crystals
Authors: Nobuyuki Itoh Nobuyuki Itoh , Kenichi Nakagawa Kenichi Nakagawa
Published: February 2005

The relationship between the molecular orientation and the optical memory angle of the surface-stabilized ferroelectric liquid crystals was investigated. We have numerically calculated the optical memory angle based on two models of director orientations, the n-director continuous and c-director continuous models, varying the surface pretilt and nonlinearity of deformation of the azimuthal angle and compared the calculation results with the measured memory angle of some FLC samples.
Absence of Superconductivity in the Mixture Y-Ba-Ag-O
Authors: Singh K. K. , P. D. Hunneyball P. D. Hunneyball , P. P. Edwards P. P. Edwards
Published: February 2005

In contrast to earlier reports, we find that the mixture Y-Ba-Ag-O does not form a compound “YBa2Ag3O
x
” in a similar fashion to YBa2Cu3O7 but rather is a combination of Ba-Y-O compounds, silver metal and unreacted starting materials. This mixture shows metallic behaviour, but no superconductivity down to 5 K. The observed metallic behaviour of these samples is almost certainly due to the presence of elemental silver. Electron probe micro-analysis (EPMA) studies show that silver does not react with Y, Ba and Ba4Y2O7 in an oxygen atmosphere. The importance of conjoint EPMA/EDAX (energy dispersive X-ray spectroscopy) and X-ray powder diffraction (XRD) studies is emphasised.
A Simple Experiment of Simulating Optical Bistability with an Oscilloscope and Photodiodes
Authors: Wang Ching-Sheu , Lau Chih-Sheng , Shy Jow-Tsong , Gou Yih-Shun
Published: February 2005

This paper presents a novel and simple hybrid optical bistable system which is composed of an oscilloscope and photodiodes. It allows us to easily control its parameters, including transmission function, feedback amplification, and time of delay feedback. Here, we will present the features of bistability, multistability and self-oscillation in this system and also the dynamical behaviors induced by the effect of the delay in the feedback loop of this optical bistable system.
Fabrication of 780-nm AlGaAs Tunable Distributed Bragg Reflector Laser Diodes by Using Compositional Disordering of a Quantum Well
Authors: Hirata Takaaki , Suehiro Masayuki , Maeda Minoru , Hihara Mamoru , Noriyuki Yamada Noriyuki Yamada , Haruo Hosomatsu Haruo Hosomatsu
Published: February 2005

AlGaAs tunable distributed Bragg reflector (DBR) laser diodes (LD's) with a lasing wavelength of 780 nm were fabricated by means of electron beam (EB) lithography, ion implantation, and two-step metalorganic vapor phase epitaxy (MOVPE). Active and passive waveguides were monolithically integrated by using silicon ion implantation for compositional disordering of quantum-well heterostructures. The optimum single-quantum-well (SQW) structure, with low threshold current and low internal loss, is about 5 nm thick and has an Al mole fraction of 0.06. The graded-index separate-confinement heterostructure (GRIN-SCH) with a carrier-blocking layer was also used to improve the characteristic temperature of a two-step-growth LD. A Iinewidth as narrow as 690 kHz and a frequency tuning of more than 1.7 THz were obtained.