bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Environment Prediction for Silicon Crystal Growth of up to 16-inch Diameters in Czochralski Furnaces
Authors: Takano Kiyotaka , Iida Tetsuhiro , Kuramoto Makoto , Machida Norihisa , Matsubara Junichi , Shiraishi Yutaka , Nobumitsu Takase Nobumitsu Takase , Hirotoshi Yamagishi Hirotoshi Yamagishi
Published: October 2002

The thermal environment in Czochralski furnaces for silicon crystals having a diameter of 6′′, 8′′, 12′′, and 16′′ is predicted through numerical simulation. To correct for the absence of melt convection factors in the simulation code, the thermal conductivity is increased for part of the molten silicon based on melt flow analysis. During the dipping process, the temperature of the quartz crucible is higher than that of the body process, and increases for larger hot zone size. This study shows that crucible temperatures during the dipping process is almost the same for 8′′ and 16′′ crystals, depending on magnetic field conditions.
Theoretical Investigation of Geometry and Electronic Structure of Layered In 2Se 3
Authors: Masato Ishikawa Masato Ishikawa , Takashi Nakayama Takashi Nakayama
Published: October 2002

The atomic configuration in layered In2Se3 has been studied from the viewpoint of electronic structure. It was found that In2Se3 stabilizes in the layered structure of Se-In-Se=In=Se, where half the In atoms have octahedral bonds (=) and the other half have tetrahedral bonds (-). This structure exhibits semiconducting properties consistent with the results of experiments. Such multicoordination of In atoms occurs due to the large electronegativity difference between In and Se atoms, which also explains why only the In-Se combination shows the layered III2VI3 structure among various III-VI misvalent combinations.
Reduction of Plasma Etching Induced Electrical Degradation in Metal-Oxide-Si Capacitors by Furnace Grown Oxides Rapid Thermal Annealed in N2O
Authors: Kuei-Shu Chang-Liao Kuei-Shu Chang-Liao , Pei-Jer Tzeng Pei-Jer Tzeng
Published: October 2002

Plasma etching induced electrical degradation in metal-oxide-silicon (MOS) capacitors is dramatically reduced by a gate oxide formed in O2 using a furnace and followed by rapid thermal annealing in N2O. The plasma etching induced reduction of charge-to-breakdown value in MOS capacitors is minimized using this technique. The plasma etching induced flatband voltage shift is significantly reduced. The electrical improvement can be explained in terms of a mechanism based on the relaxation of SiO2/Si interfacial strain.
Growth and X-ray Characterization of an InN Film on Sapphire Prepared by Metalorganic Vapor Phase Epitaxy
Authors: Wei-Kuo Chen Wei-Kuo Chen , Yung-Chung Pan Yung-Chung Pan , Heng-Ching Lin Heng-Ching Lin , Jehn Ou Jehn Ou , Wen-Hsiung Chen Wen-Hsiung Chen , Ming-Chih Lee Ming-Chih Lee
Published: October 2002

We report the successful growth of an InN film by metalorganic vapor phase epitaxy. The film quality is found to be strongly dependent on the growth temperature and the TMIn reactant flow rate. The best quality epilayer was obtained at 375°C under a high V/III ratio growth environment. It exhibits a FWHM of the X-ray rocking curve as narrow as 96 arcsec, which explains the superior crystalline quality of our epitaxial film.
High Quality Homoepitaxial GaN Grown by Molecular Beam Epitaxy with NH 3 on Surface Cracking
Authors: Markus Mayer Markus Mayer , Arthur Pelzmann Arthur Pelzmann , Markus Kamp Markus Kamp , Karl J. Ebeling Karl J. Ebeling , Henryk Teisseyre Henryk Teisseyre , Grzegorz Nowak Grzegorz Nowak , Mike Leszczyński Mike Leszczyński , Izabella Grzegory Izabella Grzegory , Sylvester Porowski Sylvester Porowski , Grzegorz Karczewski Grzegorz Karczewski
Published: October 2002

Epitaxial GaN films have been grown on GaN single-crystal substrates, using on surface cracked ammonia as nitrogen precursor for molecular beam epitaxy. With this approach excellent optical and structural properties are achieved. Low-temperature photoluminescence shows well-resolved excitonic lines with record low linewidths as narrow as 0.5 meV. The transitions are attributed to excitons bound to neutral donors ((D°, X)1 at 3.4709 eV and (D°, X)2 at 3.4718 eV) and to a neutral acceptor ((A°, X) at 3.4663 eV). In addition, free exciton lines are observed at 3.4785 eV, 3.4832 eV, and 3.499 eV for excitons A, B, and C, respectively.
Behaviors of Carbon at Initial Stages of SiC Film Grown on Thermally Oxidized Si Substrate
Authors: Miyasato Nobuo Sonoda
Published: October 2002

A silicon carbide film is grown on a thin-SiO2 layer/Si substrate by means of hydrogen plasma sputtering of a SiC target. Behaviors of the C atoms at the initial stages of the film growth are studied by depth-profile analysises and the elemental C maps for the obtained sample. The results indicate that the C atoms adsorb easily on the defective regions of the SiO2 layer. Under the conditions of the SiO2 layer thickness of 18 nm and the substrate temperature of 750°C, the adsorbed C atoms diffuse into the Si substrate through the defective regions, and the SiC phase is formed by the reaction with the substrate Si in an island region in the substrate.
Optical Properties of Manganese-Doped ZnSe/ZnS Quantum Dots Grown by Molecular Beam Epitaxy
Authors: Shen Yihong Wu , Takenari Goto Takenari Goto
Published: October 2002

Optical properties of Mn-doped ZnSe/ZnS quantum dots (QD's) have been investigated by both steady-state and time-resolved photoluminescence (PL) measurements. Strong photoluminescence associated with Mn intra-d shell transitions has been observed for QD's with a longitudinal thickness of just few monolayers (ML's). The PL decay involves two processes with different lifetimes of which the faster one has a lifetime of about 5 µs which is almost independent of the well thickness, while the other process has a lifetime varying from 40 to 80 µs when the well width decreases from 6 to 0.25 ML. The experimental results are interpreted by the use of rate equations which suggests that the enhanced Mn emission might be due to the relatively enhanced energy transfer from the QD's to the Mn atoms.
Simple Multimode Stereoscopic Liquid Crystal Display
Authors: Chen Jianmin , Kim Kyeong-Hyeon , Kim Nam-Deog , Souk Jun H. , Bos Philip J. , Shin Sung-Tae
Published: October 2002

A novel multimode stereoscopic imaging system is developed. The system consists of a polarizer and a passive liquid crystal sheet which is patterned into periodic liquid crystal configuration regions. One is in the 90° twisted nematic (TN) state while the other is in a non-twisted state (liquid crystal aligned antiparallel). This 3D imaging system can be viewed in the autostereo mode without spectacles but has discrete viewing zones and in a binocular stereo mode which requires passive polarized glasses. This system is also convertible between 2D and 3D modes. Its principle is confirmed using the test cells. The viewing angle characteristics are also investigated.
Materials Design for the Fabrication of Low-Resistivity p-Type GaN Using a Codoping Method
Authors: Yamamoto Tetsuya , Katayama-Yoshida Hiroshi
Published: October 2002

On the basis of band-theoretical investigation using the augmented-spherical-wave (ASW) method, we propose a valence-control method, the “codoping method”, to fabricate low-resistivityp-type GaN materials.p-type dopants lead to an increase in the electrostatic energy in GaN materials. This gives rise to destabilization of ionic charge distributions due to a shift of N 2plevels towards higher energy regions. We clarified that codoping ofn-type dopants, Si or O atoms, lead to a stablep-type GaN:Mg atom material and investigated differences in the roles of Si and O on the fabrication of low-resistivityp-type GaN materials.
Comparison of Homoepitaxial Growth of YBa2Cu3Oy Films on Variously Oriented YBa2Cu3Oy Single Crystals
Authors: Wen Jianguo , Zama Hideaki , Konishi Masaya , Usagawa Toshiyuki , Ishimaru Yoshihiro , Enomoto Youichi , Tadataka Morishita Tadataka Morishita , Naoki Koshizuka Naoki Koshizuka
Published: October 2002

Microstructures at interfaces of YBa2Cu3O

y

(YBCO) thin films homo-epitaxially grown on (001), (100), and (110) oriented YBCO single crystals by RF sputtering and metalorganic chemical vapor deposition (MOCVD) have been studied by transmission electron microscopy. In the case of a (001) YBCO single crystal substrate the orientation of an YBCO thin film grown by RF sputtering depends on the substrate temperature, similar to the case for normal substrates. In the case of a 2° off-cut (001) YBCO substrate grown by MOCVD, no difference of structure between the thin film and the substrate can be distinguished except for a one-unit-cell difference at the interface. When homo-epitaxy is carried out on a (100) YBCO single crystal, a high quality a-axis YBCO thin film can be obtained by either MOCVD or sputtering. Differences in microstructures for (100) and (001) homo-epitaxy are discussed in terms of the layered structure of YBCO as well as differences in growth modes.
Q-Switching and Mode Selection of Coupled-Cavity Er,Yb:Glass Lasers
Authors: Itoh Takaki , Takunori Taira Takunori Taira , Takao Kobayashi Takao Kobayashi
Published: October 2002

Q-switched, high peak power oscillation of a laser-diode pumped, compact Er,Yb:glass laser has been realized using a three mirror coupled-cavity configuration. Single-axial and multi-axial mode oscillation was successfully selected by changing of the external cavity length. We obtained a high peak output power of 920 W and a pulse energy of 8.3 µJ in multi-axial mode oscillation and 60 W in single-axial mode oscillation. The single mode oscillation was step-tunable from 1532 nm to 1542 nm. Pulse width was widely variable by increasing the pump power from 270 ns to 150 ns and from 50 ns to 8 ns for the external cavity lengths of 0.4 mm and 1.5 mm, respectively.
Temperature Dependence of Faraday Rotation in Co 2+-Substituted Hexaferrites
Authors: Shinagawa Kiminari , Simsa Zdenek , Toshiaki Saito Toshiaki Saito , Tachiro Tsushima Tachiro Tsushima
Published: October 2002

The temperature dependence of the Faraday rotation in the near-infrared wavelength region is calculated in comparison with that observed in Co2+-containing hexaferrites by using the molecular field approximation. The calculation results show that the Faraday rotation decreases in the whole wavelength region and shifts to a lower energy with an increase in temperature, which is in agreement with the experimental results.
Electrolysis by Using Diamond Thin Film Electrodes
Authors: Katsuki Nobuyuki , Wakita Shuhei , Nishiki Yoshinori , Shimamune Takayuki , Yukio Akiba Yukio Akiba , Masamori Iida Masamori Iida
Published: October 2002

Thin diamond films formed on Si substrates were electrolyzed in terms of the characteristics of their electrolysis in acidic solution for testing of the possibility of their use in industrial electrochemistry. It was found that boron doped diamond anodes (100, 1000 ppm) can be operated under conditions of severe polarization, with a current density of 10 A/cm2 in a sulfuric acid solution. It was also found that ozone gas is stably generated from boron doped diamond anodes at high current densities of over 1 A/cm2. This reveals that diamond electrodes can be used in various types of industrial electrolysis.
Complete Suppression of Color Shift in In-plane Switching Mode Liquid Crystal Displays with a Multidomain Structure Obtained by Unidirectional Rubbing
Authors: Aratani Sukekazu , Klausmann Hagen , Oh-e Masahito , Ohta Masuyuki , Ashizawa Keiichiro , Yanagawa Kazuhiko , Katsumi Kondo Katsumi Kondo
Published: October 2002

Complete suppression of color shift in in-plane switching mode liquid crystal displays (LCDs) has been realized. The LCDs have a multidomain structure obtained by unidirectional rubbing and use of zigzag electrodes. The design concept and performance of the devices are described in this paper.
90° Phase-Matched Mid-Infrared Parametric Oscillation in Undoped KTiOAsO4
Authors: Kato Kiyoshi , Tanaka Nobuhiro Umemura
Published: October 2002

90° phase-matched parametric oscillation up to 4.3 µ m was obtained in the undoped KTiOAsO4 (KTA) crystal by pumping with the 1.928 µ m output of a KTiOPO4 (KTP) parametric oscillator pumped by an Nd:YAG laser at 1.064 µ m. The oscillator is continuously tunable from 3.4 to 4.3 µ m. The improved Sellmeier's equations are presented.
Contribution of High-Velocity Particles to Stress of Thin Film Produced by Laser Ablation
Authors: Sakai Hisashi , Keitoku Susumu , Ezumi Hiromichi
Published: October 2002

The origin of stress in thin CuInSe2 films produced by laser ablation is investigated by the observation of the laser plume using the multichannel spectrometer and the laser transmittance method. As the laser energy density on the target increases above 1 J/cm2, the fraction of fast particles (atoms and ions) decreases and that of slow particles (droplets) increases. The stress in the thin film is the greatest at 1 J/cm2, and decreases below and above 1 J/cm2. From these results it is clear that the compressive stress of the thin film is caused by the peening effect due to the incidence of fast atoms and ions, and the slow, heavy species contribute to the relaxation of stress.
Doping Effect of Phosphoric Acid on the Ferroelectric Curie Point of Triglycine Sulfate
Authors: Noriyuki Nakatani Noriyuki Nakatani , Masakazu Yoshio Masakazu Yoshio
Published: October 2002

The temperature dependence of the dielectric constant of a phosphoric-acid-doped triglycine sulfate (TGSP) crystal has been measured in the vicinity of the Curie point T
c. The Curie point of TGSP shifts to a lower temperature with increasing concentration of dopant. It was revealed that the reduced shift of the Curie point ΔT
c/T
c is almost equal to the mole fraction of H3PO4 in the crystal. The number of dipole moments restrained from reversing due to doping agrees with the number of H3PO4 molecules incorporated into the crystal.
Inclined Homeotropic Alignment by Irradiation of Unpolarized UV Light
Authors: Hidefumi Yoshida Hidefumi Yoshida , Yoshio Koike Yoshio Koike
Published: October 2002

Inclined homeotropic alignment was realized by irradiation of unpolarized ultraviolet light on a polyimide film that originally exhibited homeotropic alignment. Unpolarized UV light was irradiated from an oblique direction (45-degree inclined angle) once. The liquid crystal cell with a pair of inclined homeotropic aligned substrates and nematic liquid crystal with negative dielectric anisotropy exhibits a high contrast ratio (over 1000) with a crossed Nicols configuration and a bright transmittance (same as a TN cell, around 35%).
Effect of Low-Frequency Vibration Method on Growing Huntite-Borate Crystals
Authors: Iwai Makoto , Harumura Syouji , Yusuke Mori Yusuke Mori , Takatomo Sasaki Takatomo Sasaki
Published: October 2002

We have grown huntite-borate crystals, YAl3(BO3)4and GdAl3(BO3)4using two methods; the low-frequency vibration method at a frequency of 60 Hz, and an amplitude of 0.25–1.0 mm, and the rotating seed method at a rotation rate of 100 rpm. We have compared these two methods and found that the low-frequency vibration method was more effective in the crystal growth rate almost twice and also in reduction of spontaneous nucleated crystals.
2 S/mm Transconductance InAs-Inserted-Channel Modulation Doped Field Effect Transistors with a Very Close Gate-to-Channel Separation of 14.5 nm
Authors: Xu Dong , Heiß Heiner , Sexl Markus , Kraus Stefan , Böhm Gerhard , Günther Tränkle Günther Tränkle , Günter Weimann Günter Weimann , Gerhard Abstreiter Gerhard Abstreiter
Published: October 2002

We have achieved a very small gate-to-channel separation d
gi+Δd of 14.5 nm for InAs-inserted-channel modulation doped field effect transistors (InAs-MODFETs) with the optimum control of wet-chemically recessed groove for gate electrodes. Excellent output characteristics as well as high channel current more than 1 A/mm can still be retained. The optimum wet-chemically fabricated deep recess groove leads to an absence of the influences of surface potential. Combining the Γ-gate fabrication technique, d
gi+Δd=14.5 nm produces a maximum extrinsic transconductance of 1.95 S/mm at a drain bias of 1.5 V. This is attributed to the very small gate-to-channel distance, the optimum gate fabrication technology, and the optimum channel design as well.
Perpendicular Magnetic Anisotropy of Fe–Cr–N Films Prepared by DC Reactive Sputtering
Authors: Peng Dong Liang , Sumiyama Kenji , Toyohiko J. Konno Toyohiko J. Konno , Kenji Suzuki Kenji Suzuki
Published: October 2002

Fe–Cr–N ternary films prepared by DC magnetron facing-target sputtering show perpendicular magnetic anisotropy. Upon appropriate adjustment of the chemical composition and deposition parameters, saturation magnetization of 0.37–0.5 Wb/m2 (300–400 emu/cm3) and perpendicular coercivity of 6.4×104–8.8×104 A/m (800–1100 Oe) are detected in the Fe–Cr–N films. X-ray diffraction measurements reveal that the films with large perpendicular anisotropy generally consist of the fine-grain α-F
e(C
r) phase and the γ′- (Fe, Cr)4N

x

(x<1) phase having a pronounced (200) texture. By TEM observation, we found that the nonmagnetic γ′- (Fe, Cr)4N

x

phase displays columnar growth and that the small ferromagnetic α-F
e(C
r) grains of about 2–20 nm diameter are located at grain boundaries of γ′- (Fe, Cr)4N

x

grains in the Fe71Cr20N9 film.
Passively Q-Switched Pulse Width Variation Using an Amplified Feedback Pulse Reflected from a Stimulated Brillouin Scattering Mirror
Authors: Ki Young Um Ki Young Um , Hong Jin Kong Hong Jin Kong
Published: October 2002

We present experimental and numerical results of passively Q-switched laser pulse width variation in a Nd:YAG laser oscillator and amplifier combination system using a stimulated Brillouin scattering mirror. When the laser pulse reflected from the SBS mirror returns to the oscillator, the population inversion density of the laser medium can be variably reduced, so that the Q-switched laser pulse width can be varied using the energy of the feedback pulse.
Synthesis of Diamond by DC Plasma Chemical Vapor Deposition above the Surface of a Water-Ethylene Glycol Solution
Authors: Suzuki Takeyuki , Ishihara Toshihiko , Tsutomu Yamazaki Tsutomu Yamazaki , Satoshi Wada Satoshi Wada
Published: October 2002

A new approach was used for the synthesis of diamond by the Chemical Vapor Deposition (CVD) method. The method consists of generating DC plasma between the anode substrate and the electrolyte surface under reduced pressure. With use of a water-ethylene glycol solution mixed with potassium acetate, well-faceted diamond was deposited locally on tungsten and copper substrates. Evaporation loss of the 80 mol% ethylene glycol solution was 210 m l during deposition for 2 h.
Time-Varying Autoregressive Modeling for Analyzing Transient Frequencies
Authors: Kawata Satoshi , Toshitaka Shigeoka Toshitaka Shigeoka , Osamu Nakamura Osamu Nakamura
Published: October 2002

A time-varying autoregressive model for analysis of a signal which contains several chirp signals to overcome the tradeoff problem in the resolution of time and frequency is proposed. The superiority of the time-varying autoregressive model to a short-time Fourier-transform method and wavelet analysis method is verified through computer simulation.
Impact of Plasma Effects on the High-Frequency Performance of Induced-Base Hot-Electron Transistors
Authors: Victor Ryzhii Victor Ryzhii
Published: October 2002

High-frequency performance of an induced-base hot-electron transistor (IBHET) is studied theoretically taking into account the excitation of the standing plasma waves with a linear dispersion law in its quantum well base. It is shown that the frequency-dependent small-signal transconductance of the IBHETs can exhibit sharp resonances. The resonant transconductance can markedly exceed the steady-state transconductance. The resonances can correspond to the terahertz range of frequencies and can be effectively tuned by the collector–base voltage.
Observation of Nano-Particle Formation Process in a Laser-Ablated Plume Using Imaging Spectroscopy
Authors: Junichi Muramoto Junichi Muramoto , Yoshiki Nakata Yoshiki Nakata , Tatsuo Okada Tatsuo Okada , Mitsuo Maeda Mitsuo Maeda
Published: October 2002

The behavior of atomic species and of growing nano-particles in the laser-ablated plume was observed by laser-induced fluorescence (LIF) and Rayleigh scattering (RS) imaging techniques, and the results on the ablation of silicon (Si) in a He ambient are presented. The particles were formed in a limited region in the plume with a characteristic spatial distribution. The growth of the particles was completed about 20 ms after ablation at a helium (He) ambient pressure of 1.33 kPa and 50 ms at 0.67 kPa. The spatial distributions of the particles was retained for more than one second.
Emission Studies of the Plume Produced by KrF Laser Ablation of Fe in Ambient Nitrogen Gas
Authors: Tsuyoshi Yoshitake Tsuyoshi Yoshitake
Published: October 2002

Time-resolved emission measurements for an expanding plume during laser ablation of Fe in nitrogen gas are performed. Most emissions are identified as being due to Fe neutrals and are divided into two groups with different time-of-flight distribution, which are fitted with shifted Maxwellian distribution. The most probable velocities are estimated to be 2×104 m/s and 1×104 m/s. Because of the apparent time lag between the emission of N2
+ and that of an Fe neutral, it is considered that N2
+ does not contribute to the nitridation of deposited thin film.
Relationship between Grown-in Defects in Czochralski Silicon Crystals
Authors: Umeno Shigeru , Okui Masahiko , Hourai Masataka , Masakazu Sano Masakazu Sano , Hideki Tsuya Hideki Tsuya
Published: October 2002

The relationship between flow pattern defects (FPDs), Secco etch pit defects (SEPDs), defects detected by IR light scattering tomography (LSTDs) and defects detected by an optical precipitate profiler (OPP-defects) was investigated in the same area of as-grown and annealed wafers. It was concluded that the relationship between grown-in defects in as-grown Czochralski silicon crystals is expressed as LSTDs=OPP-defects=FPDs+SEPDs. FPDs were decreased after annealing, but LSTDs were still observed at the positions where the LSTDs were detected in the as-grown state. It was found that the origins of FPDs are not annihilated during annealing.
Vapor Phase Epitaxy of InxGa1-xN Using InCl3, GaCl3 and NH3 Sources
Authors: Takahashi Naoyuki , Matsumoto Ryu , Akinori Koukitu Akinori Koukitu , Hisashi Seki Hisashi Seki
Published: October 2002

Epitaxial growth of In

x

Ga1-
x

N on a GaN buffer layer/(0001) sapphire substrate by halide vapor phase epitaxy is reported for the first time. It is shown that the growth rate of the InGaN alloy at a constant input mole ratio of group III sources decreases with increasing growth temperature from 700 to 825° C. The solid composition of epitaxial layers becomes more GaN-rich with increasing growth temperature. At all temperatures, preferential deposition of the GaN component is observed. The preferential deposition is discussed briefly from a thermodynamical point of view.
Lattice Matching and Relaxation of Vanadyl-Phthalocyanine Crystal Epitaxially Grown on Mixed Crystals of Alkali Halides
Authors: Nakao Satoru , Gomyou Makoto , Hoshi Hajime , Ken Ishikawa Ken Ishikawa , Hideo Takezoe Hideo Takezoe
Published: October 2002

The lattice constants of vanadyl-phthalocyanine (VOPc) films epitaxially grown on KCl/KBr mixed-crystal substrates have been studied as a function of film thickness. The transmission electron diffraction pattern indicates that the films detached from the substrates have a constant lattice constant irrespective of that of the substrates and the orientation of the VOPc lattice. According to a reflection high-energy electron diffraction pattern, the VOPc film starts to grow under a lattice-matching condition at the first layer, but the lattice rapidly relaxes from the second layer. The acceptable lattice mismatch in this system is also discussed.
Wavelet Application for Reflectometry of Plasma Density Profiles
Authors: G. Bruskin Leonid , Atsushi Mase Atsushi Mase , Tokihiko Tokuzawa Tokihiko Tokuzawa , Naoyuki Oyama Naoyuki Oyama , Akiyosi Itakura Akiyosi Itakura , Teruo Tamano Teruo Tamano
Published: October 2002

A new method of plasma density profile reconstruction in microwave reflectometry is proposed and implemented on an ultra-fast swept broadband reflectometer of a GAMMA10 mirror device. The proposed method makes use of the wavelet transform of the detected signal. Excellent resolution in the time-frequency domain, inherent to wavelet analysis, allows one to obtain an electron density radial profile for almost every frequency sweep. A wavelet-based profile reconstruction algorithm is especially advantageous for monitoring transient plasma phenomena and fast processes, such as in pellet injection, ultra-fast swept reflectometry and short pulsed reflectometry.
All-Solid-State Electrochromic Display Device of Prussian Blue and WO3 Particulate Film
Authors: Su Lianyong , Fang Jinghuai , Bingjie Liang Bingjie Liang , Zuhong Lu Zuhong Lu
Published: October 2002

A new all-solid-state electrochromic device (SED) employing prussian blue and WO3 particulate film with poly (vinyl chloride) (PVC) gel electrolyte has been fabricated. A reversible color change between blue and colorless was observed when an appropriate potential was applied repeatedly to the SED. When the potential cycled more than 1000 times, less than 2% of the electrochromic characteristics were lost.
(Ga, Mn)As/GaAs Diluted Magnetic Semiconductor Superlattice Structures Prepared by Molecular Beam Epitaxy
Authors: Shen Aidong , Ohno Hideo , Matsukura Fumihiro , Sugawara Yasuhiro , Ohno Yuzo , Akiba Norimitsu , Kuroiwa Tatsuo
Published: October 2002

A (Ga, Mn)As/GaAs superlattice, a semiconductor-based ferromagnetic/non-magnetic multilayer system, was prepared by low-temperature molecular beam epitaxy. X-ray diffraction measurements showed that the superlattice structure has high crystal perfection and good interface quality. Magnetotransport measurements revealed the presence of ferromagnetic order in the multilayer system at low temperatures.
Photon Correlation Spectroscopy of the Phase Mode in a Ferroelectric Liquid Crystal under a DC Electric Field
Authors: Yasuyuki Kimura Yasuyuki Kimura , Hiroshi Inoue Hiroshi Inoue , Reinosuke Hayakawa Reinosuke Hayakawa
Published: October 2002

The phase mode in a ferroelectric liquid crystal has been studied by photon correlation spectroscopy under a dc electric field applied perpendicular to the helical axis of the liquid crystal. The parabolic continuous dispersion of the inverse correlation time τ-1 against the scattering wave number splits into two branches with a gap at nearly half the wave number at which τ-1 takes a minimum value. The gap frequency is found to increase in proportion to the applied electric field below the critical field E
c where the helical structure completely unwinds. Above E
c, τ-1 increases continuously with the wave number and shows no minimum. The experimental findings are compared with the recent predictions based on the phenomenological theory.
Dependence of Anisotropic Strain Relaxation on Composition of Lattice-Mismatched InGaAsP
Authors: Guk Jeong Sang-Wan Ryu , Byung-Doo Choe Byung-Doo Choe
Published: October 2002

The strain relaxation behavior of compressively strained InGaAsP grown on InP is studied using double-crystal X-ray diffractometry. The residual strain in compressively strained InGaAsP of various thicknesses follows the half-loop nucleation model. Anisotropic relaxation is observed, and the preferential direction of relaxation is found to change with the composition of InGaAsP. In the quaternary InGaAsP epilayers studied, the relaxation along [110] is larger than that along [110], but the direction is reversed for the ternary InGaAs and InAsP. The change in the direction of the preferential relaxation is thought to be caused by a change in the critical stress and the dislocation velocity as the composition of the epilayer is changed.
Determination of Surface Impurities on a Gallium Arsenide Wafer by Inductively Coupled Plasma Mass Spectrometry
Authors: Kozuka Shoji , Sugamoto Junji , Furukawa Kazuyoshi , Masaru Hayashi Masaru Hayashi
Published: October 2002

The surface impurities on a GaAs wafer were determined by inductively coupled plasma mass spectrometry to clarify the diffusion behavior which affected the layer construction. The sample was etched by hydrofluoric acid in a PTFE vessel at room temperature. Depth analysis of the wafer was performed by repeated etching as impurities were thought to exist near the wafer surface. Copper was difficult to dissolve by hydrofluoric acid due to an ionization tendency compared to the hydrogen ion. The method used in this study was demonstrated to be effective for determining surface impurities on a GaAs wafer for an impurity level of 1011 atoms/cm2 and for analyzing depth profiles from the surface.
Preparation of A-axis Oriented YBa2Cu3O7-y Films by Metalorganic Chemical Vapor Deposition Using Liquid Sources
Authors: Yoshida Yutaka , Ito Yoshiaki , Nagai Hisashi , Takai Yoshiaki , Izumi Hirabayashi Izumi Hirabayashi
Published: October 2002

Superconducting YBa2Cu3O7-
y

(YBCO) thin films were prepared on SrTiO3(100), NdGaO3(110) and LaAlO3(100) single crystalline substrates by metalorganic chemical vapor deposition (MOCVD) using various kinds of liquid sources. Films deposited using Ba(DPM)2·tetraen on SrTiO3(100) at temperatures between 650° C and 700° C were strongly a-axis oriented. Furthermore, films deposited in the same temperature range, but grown on NdGaO3(110) and LaAlO3(100), showed a-/b-axis mixed orientation and b-axis orientation, respectively. Thus, deposition using liquid sources enables us to control the orientation in MOCVD, which has never been attained.
Structural and Electrical Properties of Ba0.5Sr0.5TiO3 Films on Ir and IrO2 Electrodes
Authors: Cho Hag-Ju , Kang Chang Seok , Hwang Cheol Seong , Kim Jin-Won , Horii Hideki , Lee Byoung Taek , Sang In Lee Sang In Lee , Moon Yong Lee Moon Yong Lee
Published: October 2002

High-dielectric Ba0.5Sr0.5TiO3 (BST) thin films are grown on Ir and IrO2 electrodes by a rf sputtering method. The structural and electrical properties of BST films are investigated. After postannealing at 750° C for 30 min in N2 atmosphere, the interface between BST and IrO2 remains flat and the IrO2 does not show any structural change. On the other hand, a thin IrO2 layer is formed at the interface between the BST and Ir after the same post-annealing. A larger grain size of BST film is obtained on the Ir electrode compared to that of BST film on the IrO2 electrode. Dielectric constants of 36-nm-thick BST films on Ir and IrO2 are 338 and 290, respectively. The leakage current densities of both the Pt/BST/Ir and Pt/BST/IrO2 capacitors are about 20 nA/cm2 at ±1.5 V, which is sufficiently small for application to dynamic random access memory devices.
Cross-Sectional Transmission Electron Microscopy Study of Si/SiGe Heterojunction Bipolar Transistor Structure Grown by Ultra-High Vacuum Chemical Vapor Deposition
Authors: Zhang Jinshu , Jin Xiaojun , Lo Pei-Hsin Tsien
Published: October 2002

Si/SiGe heterojunction bipolar transistor (HBT) structure, grown by ultra-high vacuum chemical vapor deposition (UHVCVD), was investigated with cross-sectional transmission electron microscopy (XTEM). It was determined that a very thin layer exists in the strained SiGe layer grown on Si, which is in parallel to the interface of SiGe and Si, and the position of thin layer changes with the intrinsic SiGe spacer width but not with the Ge content in the strained SiGe base layer. The base collector junction turn-on voltage of the HBT decreases from ∼0.6 V to ∼0.2 V when the spacer width decreases from 100 A to 75 A, and increases from ∼0.2 V to ∼0.4 V when the Ge content in the strained SiGe base layer decreases from 16% to 10%. A possible explanation for this phenomenon is that the Ge atom accumulates to form a very thin Ge-rich layer.
Suppression of Chaotic Oscillations in a Diode-Pumped Microchip Laser with Frequency-Shifted Optical Feedback
Authors: Uchida Atsushi , Takahiro Sato Takahiro Sato , Masahiro Takeoka Masahiro Takeoka , Fumihiko Kannari Fumihiko Kannari
Published: October 2002

Suppression of chaotic instability arising in a single-mode Nd:YVO4 microchip laser subject to frequency-shifted optical feedback is numerically demonstrated by sinusoidally modulating the population inversion. Many modes of stable periodic oscillation can be obtained from one chaotic oscillation simply by selecting appropriate modulation parameters.
Crystal Growth and Structural Characterization of New Piezoelectric Material La3Ta0.5Ga5.5O14
Authors: Takeda Hiroaki , Sugiyama Kazumasa , Inaba Katsuhiko , Kiyoshi Shimamura Kiyoshi Shimamura , Tsuguo Fukuda Tsuguo Fukuda
Published: October 2002

New piezoelectric La3Ta0.5Ga5.5O14 bulk single crystals were grown using the Czochralski technique. The crystal structure (space group P321, a=8.228(2), c=5.124(2) Å) has been refined using single-crystal X-ray diffraction data with a precision corresponding to an R index of 0.04. Ta atoms were found to be ordered in the octahedral site coordinated by six oxygen atoms.
Low Temperature Nucleation of the Perovskite Phase in the Deposition of Pb(Zr,Ti)O 3 Films on the Pt/SiO 2/Si Substrate by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition
Authors: Jae-Whan Kim Jae-Whan Kim , Hyun-Ho Kim Hyun-Ho Kim , Dang-Moon Wee Dang-Moon Wee , Won-Jong Lee Won-Jong Lee
Published: October 2002

PZT films were deposited on the Pt/SiO2/Si at 450–480°C by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) and the nucleation behavior of those films was investigated. Above 470°C, pure perovskite phase PZT films were obtained. At the initial stage of the film deposition, an interfacial pyrochlore phase was formed. However, it was transformed to the perovskite phase as the deposition process proceeded. Below 460°C, a non-perovskite phase was formed and the composition was deviated from the stoichiometry. By introducing lead titanate seed layer, pure perovskite PZT films with stoichiometric composition could be fabricated even below 460°C for the wide range of Zr/Ti concentration ratio.
Imaging of Proteins Adsorbed on Self-Assembled Monolayers by Atomic Force Microscopy in Liquid
Authors: Umemura Kazuo , Hara Masahiko , Hiroyuki Sasabe Hiroyuki Sasabe , Wolfgang Knoll Wolfgang Knoll
Published: October 2002

Atomic force microscopy (AFM) imaging of proteins adsorbed on Au(111) substrates was examined. When Au(111) was modified with 4-mercaptopyridine self-assembled monolayers (SAM), uniformly adsorbed hemoglobin molecules were observed on the substrate in a physiological buffer solution. In contrast, very few molecules were observed on octadecanethiol SAM. When the bare Au(111) was used without surface modification, unclear AFM images were obtained although protein molecules might have been adsorbed. The results suggested that the adsorption phenomenon of metalloproteins is strongly affected by surface modification of the gold substrate. In addition, our data indicated that the adsorbed metalloproteins on SAM could be successfully observed by tapping mode AFM in physiological solution without chemical fixation of protein molecules.
High Crystallinity Poly-SixGe1-x at 450° C on Amorphous Substrates
Authors: Shiota Kunihiro , Inoue Daisuke , Minami Koichiro , Yamamoto Masaji , Hanna Jun-ichi
Published: October 2002

The composition variation and strutural properties of poly-SiGe thin films prepared by Reactive Thermal chemical vapor deposition (CVD) with Si2H6 and GeF4 were investigated. Deposition of the films at 450° C was carried out with various gas flow ratios of Si2H6 to GeF4 on amorphous substrates such as glass plates and oxidized silicon wafers. The structural profiles of films were characterized by X-ray diffraction (XRD) and Raman scattering spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All films show high crystallinity and (220) prefered orientation. The mole fractions of Si in the Si

x

Ge1-
x

films were estimated to be from 0.95 to 0.05 for x, using Vegard's law for the XRD peaks. Crystallinity in the Si-rich films was affected by growth rate and was greatly improved at lower growth rates. TEM observation revealed that high crystallinity was well established, even in poly- Si0.95Ge0.05 film, owing to direct polycrystalline layer growth on the substrate surface.
Self-Aligned Local Channel Implantation Using Reverse Gate Pattern for Deep Submicron Dynamic Random Access Memory Cell Transistors
Authors: Ha Daewon , Sim Jai-hoon , Kim Kinam
Published: October 2002

In this paper, we propose the highly manufacturable self-aligned local channel implant (SALCI) cell structure for dynamic random access memory of 4 Gb and larger. For conventional cell transistors, data retention degradation caused by the junction leakage current and capacitance become unavoidable as the gate length is scaled down, due to the highly doped channel. In order to achieve more enhanced and reliable performance under low-voltage operation, decreasing substrate doping beneath the source/drain junction while maintaining high substrate doping at the channel region by means of the self-aligned local channel implant without additional photomask steps will be very useful.
Location Control of Large Grain Following Excimer-Laser Melting of Si Thin-Films
Authors: Ishihara Ryoichi , Burtsev Artyom
Published: October 2002

We propose a method to locate a large silicon (Si) crystal grain at a predetermined position on a glass substrate following excimer-laser melting of Si thin-film. The thickness of part of the intermediate insulator of the amorphous-Si (a-Si)/insulator/metal/glass structure was increased. After the irradiation by dual-beam light to both the back and front sides of the structure, a Si crystal grain as large as 4 µm was located exactly at the center of the predetermined position, for wide range of diameter of the thick portion and irradiated light energy density.
Enhancement of Giant Magnetoresistance in NiCoFe/Cu/Co with a Ag Capping Layer Prepared by Sputtering
Authors: Sugita Yasunari , Satomi Mitsuo , Kawawake Yasuhiro , Sakakima Hiroshi
Published: October 2002

Enhancement of giant magnetoresistance (GMR) in NiCoFe/Cu/Co with the addition of Cu/Ag capping layers prepared by sputtering on Si(001) single crystal substrates with Cu buffer layer was observed. This enhancement of magnetoresistance (MR) ratio may be attributed to the specular scattering of conduction electrons at the surface of the Ag capping layer. The dependence of the MR ratio on the Ag capping layer thickness was visible in the broad peaks at around t(Ag)=2 nm.
The Interfacial and Diffusion Properties of Copper on Polyimide Deposited by Ionized Cluster Beam
Authors: Kim Nam Young , Yoon Hyuong-Seek , Lee Youn-Seung , Lim Kwan Yong , Kim Ki Won , Whang Chung Nam
Published: October 2002

Polyimide (PI) films have been prepared by ionized cluster beam deposition (ICBD), and Kapton, which is the trademark of PI from DuPont, was also prepared. Copper was deposited by sputtering on PI films. We investigated the interfacial properties of these two systems by X-ray photoelectron spectroscopy (XPS), and the diffusion phenomena by Rutherford backscattering spectroscopy (RBS). In addition, the packing densities of these PI films were measured by a rotational analyzer (RA) type ellipsometer. Two Cu/PI systems are compared. We found that PI films deposited by ICBD (ICB-PI) have a higher packing density than Kapton. We found that Cu interacts with pyromellitic dianhydride (PMDA) part of PI in the form of Cu–C–N, Cu–C–O, Cu–N–O complex, and that the interface of Cu/ICB-PI is sharper than Cu/Kapton. We also found that less copper is diffused into ICB-PI than into Kapton. The diffusion coefficient of Cu/ICB-PI is 2.45×10-17–2.8×10-15 cm2/s at 300–390°C, the activation energy of Cu diffusion into ICB-PI is 1.75 eV and D
0 for ICB-PI is 1.92 ×10-1 cm2/s. The Cu atoms diffused into PI as a form of Clusters.
Characterization of Corner-Induced Leakage Current of a Shallow Silicided n+/p Junction for Quarter-Micron MOSFETs
Authors: Lee Hi-Deok , Lee Sang-Gi , Lee Seung-Ho , Lee Young-Jong , Hwang Jeong-Mo
Published: October 2002

In addition to the conventional area and perimeter intensive junctions, a corner intensive junction has been added to characterize the reverse current mechanism of a silicided shallow n+/p junction for quarter-micron metal oxide silicon field effect transistors (MOSFETs). The n+/p junction is fabricated using the novel quarter micron technology. The corner intensive junction shows a much larger reverse current than the area and perimeter intensive junctions. The main causes of reverse current in these three junctions are Poole-Frenkel barrier lowering and possibly phonon-assisted tunneling. Although additional phosphorus ion implantation improves junction quality of the area and perimeter diodes, it has had little effect on the corner diode. The corner diode shows a strong electric field dependence in spite of additional phosphorus ion implantation. The main cause of corner leakage current is believed to be the increased trap density and electric field at the corner area. As the MOSFET device shrinks, the corner leakage component will be important.
Oxygen δ-Doped Si Multi-Layers Grown by Molecular Beam Epitaxy
Authors: Sheng Chi , Lin Feng , Gong Dawei , Wan Jun , Fan Yonglian , Wang Xun
Published: October 2002

An oxygen δ-doped Si multilayer structure has been grown by molecular beam epitaxy (MBE). Thermal oxidation of a Si layer prepared by an MBE system at a low oxygen partial pressure resulted in a thin ordered oxide layer with a very flat surface. On the ordered oxide, Si was epitaxied through the solid phase epitaxy. Five periods of Si(2 nm)/SiO
x
(1 nm) multilayers were grown successfully. The O-doped Si layer (SiO
x
) was composed of 7 atomic layers and the crystalline structure of the SiO
x
layer was the same as that of the Si substrate but had a relatively transverse displacement. The in-plane stress restricted the number of the oxide layers grown to a thickness of less than 6 atomic layers. This structure may be the gateway for realizing Si-based quantum wells.
Current Status of 200 mm and 300 mm Silicon Wafers
Authors: Huff Howard R. , McCormack D. W. , Au Jr. , Messina Troy , Chan Kevin , Goodall Randal K.
Published: October 2002

Encouraging characterization data for 300 mm polished developmental wafers has been obtained, indicating individual parameter data in some cases comparable to or even exceeding state-of-the-art 200 mm epitaxial wafers. Initial oxygen precipitation data in 300 mm sectioned wafers indicates behavior consistent with previously observed phenomenon. Nevertheless, extensive work is required for further clarification and detailed comparison to 200 mm behavior.
Second Harmonic Generation as a Nondestructive Readout of Optical (Photo(electro)chromic and Magnetic) Memories
Authors: Fedyanin O. A. Aktsipetrov , Melnikov A. V. , E. D. Mishina E. D. Mishina , T. V. Murzina T. V. Murzina
Published: October 2002

Optical second harmonic generation (SHG) is suggested as a nonlinear-optical nondestructive readout of (thin) film-based optical memories. Systematic studies of photoinduced, electroinduced, and magnetoinduced variations in the anisotropic SHG intensity in (i) thin solid photo(electro)chromic films of bacteriorhodopsin, (ii) photosensitive Langmuir-Blodgett films of 4-nitro-4'-N-octadecylazobenzene, and (iii) rare-earth iron garnet films show sufficient modification of their nonlinear-optical properties by these external factors. These photo-, electro- and magnetomodified nonlinear-optical properties of thin films being used for recording the information can be easily distinguished by the SHG readout. The IR fundamental radiation used for the excitation of the SHG is shown not to disturb the information recorded in photo(electro)chromic memories. For, what is to our knowledge, the first time, the surface-bulk crossterms in the SHG intensity originating from the interference of the crystalline and magnetization induced second harmonic fields are observed in magnetic iron garnet films.
Medium Field Breakdown Origin on Metal Oxide Semiconductor Capacitor Containing Grown-in Czochralski Silicon Crystal Defects
Authors: Tamatsuka Masaro , Radzimski Zbigniew , Rozgonyi George A. , Oka Satoshi , Kato Masahiro , Kitagawara Yutaka
Published: October 2002

The medium field breakdown of metal oxide semiconductor capacitor due to the Czochralski silicon crystal originated defect was studied in view of both electrical and structural analyses. By analyzing the local tunneling current which initiates the medium field breakdown, phenomenological defect sizes were calculated from the local tunneling current by assuming the local oxide thinning model. They were the defect diameter as 5 to 50 nm and the local oxide thinning as ∼25 nm. These data were confirmed by direct defect observation using high precision defect isolation procedure followed by transmission electron microscopy. Direct observation revealed that the real defect size was ∼200 nm which correlated well with other recently reported works. The real local oxide thinning,however,was not as large as phenomenological calculation. To explain the differences between phenomenological and real local oxide thinning, the poly-Si grain protrusion induced stress model was proposed.
Precise Measurement of Strain Induced by Local Oxidation in Thin Silicon Layers of Silicon-on-Insulator Structures
Authors: Shigeru Kimura Shigeru Kimura , Atsushi Ogura Atsushi Ogura
Published: October 2002

We used X-ray diffraction to quantitatively measure the strain induced by the local oxidation of silicon in thin-film silicon-on-insulator (SOI) wafers. In the samples of bonded SOI wafers thinned by plasma-assisted chemical etching, the reflection peaks of the top Si layer and the base Si substrate could be measured independently because the orientation of these lattice planes differs slightly. Moreover, the strain near the surface region could be measured because the top Si layer is only 200-nm thick. We show that the strain in the SOI wafers is more than one order of magnitude larger than that in the bulk wafers when the device region is fully isolated by the surrounding SiO2.
The Effect of Al/Pt Interface Reaction on Lead-zirconate-titanate Capacitor and the Optimization of Via Contact for Double Metal Ferroelectric RAM
Authors: Hwang Yoo-Sang , Lee Jin-Woo , Lee Sung-Yung , Koo Bon-Jae , Jung Dong-Jin , Chun Yoon-Soo , Lee Mi-Hyang , Shin Dong-Won , Shin Soo-Ho , Lee Sang-Eun , Kim Byung-Hee , Kang Nam-Soo , Kim Ki-Nam
Published: October 2002

The effect of the platinum and aluminum interface reaction on the capacitor properties were investigated in 64 k ferroelectric random access memory (RAM). Aluminum diffused into platinum and reacted to form an intermetallic compound during the post-anneal when aluminum had direct contact with the top platinum layer of the ferroelectric capacitor. The Al/Pt/PZT contact was changed into an Al–Pt and lead-zirconate-titanate contact by the reaction. As a result, ferroelectric properties degraded and the leakage current of the top electrode and lead-zirconate-tianate contact started to increase after annealing at 300°C. The capacitor structure was destroyed by the volume expansion due to the Al/Pt reaction at 400°C. To prevent this reaction, a TiN layer was introduced as the barrier layer. This contact scheme showed no breakdown of the ferroelectric capacitor up to 400°C, which indicated that TiN acts as a good diffusion barrier for the double-metal process.