bluuebunny/crossref_metadata_2025 huggingface dataset:
Radius of Curvature Considerations for Direct Wafer Bonding
Authors: Hong Linh N. , Bower Robert W.
Published: October 2002

A study of the bondability of silicon samples that deviate from the ideal flatness (radius of curvature, R, greater 100 m) of industrial standard wafers is the major objective of this work. A theoretical model is developed to predict the force required to conform two silicon samples and the resultant radius of curvature of the pair; this model is based on the elastic deformation of thin plates. Experimental verification of this model is also examined. Silicon samples with a radius of curvatures as small as 15 m are used. These large deflections of the silicon samples are created by deposition of plasma enhanced chemical vapor deposition (PECVD) nitride film. Utilizing a NH3 plasma surface treatment prelude to bonding and a 300 °C pressure anneal for 1 h , conformal silicon samples were formed.
Ultrafast Processes of Highly Excited Carriers in CdSxSe1-x-Doped Glass
Authors: Zhang Xiaojie , Izutsu Masayuki
Published: October 2002

Femtosecond pump-probe experiments were conducted, and transient absorption
spectra showing ultrafast dynamic processes of highly excited carriers were observed
in a glass doped with microcrystalline CdS
x
Se1-x
(average particle diameter of 2 nm).
A relaxation process with a time constant of about 2 ps was obtained. This was the first
observation of a 2-ps dynamic process occurring over a very wide spectral range, and
the process can be understood as the relaxation of the excited carriers in the
dangling-bond surface states. A residual increment in absorption was evident after the
relaxation.
The Vibrational-Translational Energy Transfer in Binary Mixtures: Influence of the Vibrational Mode Close to the Lowest Mode in Group Relaxation
Authors: Sakurai Takashi , Asai Masataka , Matsuoka Tatsuro , Koda Shinobu , Nomura Hiroyasu
Published: October 2002

The energy transfer between vibrational and translational (V-T)
degrees of freedom in the presence of a vibrational mode, which is close to
an other vibrational mode in another molecule, has been investigated. The
ultrasonic velocities of bromoform-bromoform-d and chloroform-d-1,1,2-trichloroethane mixtures were measured in the frequency range from 100 MHz to 5 GHz by the three ultrasonic methods; high-resolution Bragg
reflection, coherent Brillouin scattering and Brillouin scattering. The
velocity dispersions due to the V-T energy transfer were observed in pure
liquids and binary mixtures. The relaxation strength in the binary
mixtures can be represented with the additivity of relaxation strength with
regard to the components. These results indicate that the effect of the
intermolecular vibrational-vibrational energy transfer on the V-T energy
transfer is small.
Reaction of Hydrogen Fluoride Gas at High Temperatures with Silicon Oxide Film and Silicon Surface
Authors: Hitoshi Habuka Hitoshi Habuka , Toru Otsuka Toru Otsuka
Published: October 2002

The chemical nature of hydrogen fluoride gas at high temperatures,
523–1173 K, for etching silicon dioxide
in hydrogen ambient at atmospheric pressure
is studied,
for the first time.
Although only a slight decrease in the silicon dioxide film thickness
can be observed below 1000 K,
its surface is significantly etched above 1000 K.
Hydrogen fluoride gas in the temperature range
of 500-1000 K in hydrogen ambient is experimentally
shown to be nonreactive with silicon dioxide.
The existence of water molecules
is necessary for hydrogen fluoride gas
to etch silicon dioxide
even at high temperatures.
At temperatures above 873 K,
hydrogen fluoride gas can react to roughen
the surface of the silicon substrate.
The corrosion of silicon carbide
by hydrogen fluoride gas is also observed
as the formation of pits at the surface.
Effect of Surface Treatments on Adsorption and Tribology of the Diamond-Like-Carbon Layer for Metal-Evaporated Tape
Authors: Miyamura Takeshi , Yoshida Osamu , Endo Katsumi , Ishikawa Akira , Kitaori Noriyuki
Published: October 2002

Metal-evaporated (ME) tape presents greater problems for
smooth tracking and has poor durability than metal-particulate
(MP) tape; a diamond-like-carbon (DLC) layer and a lubricant
layer were used to cover the magnetic layer to overcome these
problems. The surface state of the DLC protective layer must be
controlled to enable the adsorption of fluorine of the lubricant. We
investigated the surface state of the DLC protective layer using
three types of surface treatments–aqua dipping, N2 plasma
treatment, and a combination of the two–to study the change in
lubricant adsorption. We found that N2 plasma treatment
provided the most favorable surface for the realizaton of optimal
ME tape properties.
Y2O3-Stabilized ZrO2 Thin Films Prepared by Metalorganic Chemical Vapor Deposition
Authors: Tomokazu Matsuzaki Tomokazu Matsuzaki , Norikazu Okuda Norikazu Okuda , Kazuo Shinozaki Kazuo Shinozaki , Nobuyasu Mizutani Nobuyasu Mizutani , Hiroshi Funakubo Hiroshi Funakubo
Published: October 2002

Zirconia films stabilized by Y2O3 were deposited by metal-organic chemical vapor techniques onto various crystalline substrates.
Y2O3, ZrO2 and mixtures of these two were deposited and characterized.
The deposition rate, the film composition and the structure could be systematically varied through the Y(C11H19O2)3, Zr(O·t-C4H9)4 and O2 source gas ratios and the substrate temperature.
The Y/Zr ratio could be adjusted by controlling the ratio in Y(C11H19O2)3 to Zr(O·t-C4H9)4 partial pressures.
However, the Y/Zr ratio was found to be smaller than that estimated based on the deposition rates of unmixed Y2O3 and ZrO2 films.
The activation energy of the Y2O3 component in YSZ film growth was similar to that of the ZrO2 component in YSZ films.
These YSZ values were more than 4 times larger than those of unmixed Y2O3 or ZrO2 films.
Decomposition of Ployvinylchloride using Supercritical Water
Authors: Sato Yoshiyuki , Kato Kiyoshi , Takeshita Yukitoshi , Takahashi Kazue , Nishi Shiro
Published: October 2002

Various organic compounds were obtained after decomposition of Polyvinylchloride using supercritical water. This shows the possibility of using supercritical-water treatment technology in the feedstock recycling of PVC waste. The chlorine atoms in the PVC were recovered as HCl in water, which shows the toxicological safety of this technique.
Epitaxial Growth of C54 TiSi2 on Si(001) by Self-Aligned Process
Authors: Wang Li-Ming , Wu Shinn-Tyan
Published: October 2002

Titanium films of 35 nm thickness are deposited on Si(001) by direct current magnetron sputtering. Rapid thermal annealing (RTA) in nitrogen atmosphere is performed on the films for 20 s at 670°C. The residual titanium is etched off with a solution of H2O2:NH4OH:H2O (1:1:5). A second RTA at 900°C for 10 s is applied again. The result is a C54 phase of TiSi2 of 65 nm thickness. By means of X-ray diffraction analysis, transmission electron microscopy and superlattice mismatch calculation, two epitaxial relationships: (004)C54//(001)Si, [11 3 0]C54//[110]Si and (311)C54//(001)Si, [271]C54//[110]Si are established.
Use of a Two-Dimensional Array Illumination in Laser Machining for Improving Throughput
Authors: Amako Jun , Umetsu Kazushige
Published: October 2002

We report a laser-machining method that uses a two-dimensional array of beam spots to attain a high throughput. A phase grating is used as an array
generator. Multiple spots lined up parallel as well as perpendicular to the
machining direction are beamed on a workpiece atop a table, leaving marks.
The mark size and spacing and the table speed are mutually related in a way
that allows the said marks to overlap each other to process the workpiece.
Theoretically, the use of m spots, compared to a single spot, in the machining
direction enables an m-time increase in throughput. To corroborate the idea
experimentally, we cut a photoconductive film with a pair of spots and found
cutting throughput to be doubled.
Electronic Structures of PbTiO3: II. Properties of Pb Ion Displacement
Authors: Kaoru Miura Kaoru Miura , Masahiro Tanaka Masahiro Tanaka
Published: October 2002

Properties of lead ion displacement in PbTiO3 were studied in reference to the electronic structures.
Appearance of lead ion displacement is not independent of the existence of the Madelung potential but is strongly dependent on the existence of titanium ion displacement.
This result is in contrast with our previous calculated result that titanium ion displacement appears without lead ion displacement, but is consistent with the experimental result of the properties of displacements of Ti and Pb ions below the phase-transition temperature.
Our calculated results suggest that the softening of the Slater mode occurs before the softening of the Last mode.
Influence of Buffer Materials on the Pyroelectric Properties of (Pb0.9La0.1)TiO3 Thin Films
Authors: Yung-Kuan Tseng Yung-Kuan Tseng , Kuo-Shung Liu Kuo-Shung Liu , Jian-Der Jiang Jian-Der Jiang , I-Nan Lin I-Nan Lin
Published: October 2002

The effects of the LaNiO3 (LNO) and SrRuO3 (SRO) buffer layers on the characteristics of the subsequently deposited (Pb0.9La0.1)TiO3 (PLT) thin films were examined. The Pt-layer precoated on Si-substrates results in tetragonal perovskite PLT/LNO/Pt/Si and PLT/SRO/Pt/Si films, which possess ferroelectric properties superior to the cubic films (PLT/LNO/Si3N4/Si). Using SrRuO3 layers in lieu of LaNiO3 layers as buffer materials significantly improves the ferroelectric behavior of PLT thin films. The optimized electrical properties are: K=460, P
r=15 µC/cm2, E
c=25 kV/cm, J
L = 8 ×10-7 A/cm2 (at 50 kV/cm) and p=0.304 µC/cm2·K for the PLT/SRO/Pt/Si thin films deposited at 500°C substrate temperature.
Analysis of Convective Heat Losses in JT-60U Neutral Beam Injection Experiments
Authors: Alexei Polevoi Alexei Polevoi , Sergei Neudatchin Sergei Neudatchin , Hiroshi Shirai Hiroshi Shirai , Tomonori Takizuka Tomonori Takizuka
Published: October 2002

The role of convective heat losses in tokamak plasmas is studied analytically and numerically. One of the natural forms of the energy confinement scaling law is suggested. The ion temperature limit in the steady-state neutral beam injection discharges caused by convective heat losses is obtained. A new technique for the determination of convective heat losses from experimental measurements is applied to the analysis of a JT-60U NBI discharge. The particle source and convective heat losses calculated directly from the experimental data are in a good agreement with ASTRA calculations. The convective heat loss obtained from the data is about 50% of the absorbed NB power.
High Transmittance SiC Membrane Prepared by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition in Combination with Rapid Thermal Annealing
Authors: Seung Yoon Lee Seung Yoon Lee , Ki Chang Song Ki Chang Song , Jiyoung Kim Jiyoung Kim , Joo-Hiuk Son Joo-Hiuk Son , Jinho Ahn Jinho Ahn
Published: October 2002

A thin film of SiC was deposited by electron cyclotron resonance plasma chemical vapor deposition (ECR plasma CVD) method for an X-ray mask membrane, and its physical and chemical properties were characterized. The source gases were SiH4, CH4, and Ar, and the stoichiometric film composition was achieved at a source gas ratio (SiH4/CH4) of 0.4, microwave power of 500 W, and deposition temperature of 600°C. At these deposition conditions, the as-deposited film had compressive residual stress of about 100 MPa. According to the transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses, the microstructure of this SiC was an amorphous matrix embedded with nano-sized crystalline particles. The compressive residual stress could be changed to tensile stress via rapid thermal annealing in N2 atmosphere without any notable structural changes. The membrane made of this SiC film had elastic modulus of 300 GPa, and showed optical transmittance of 85% at 633 nm wavelength.
Annealing and Synchrotron Radiation Irradiation Effects on Hydrogen Terminated Si(100) Surfaces Investigated by Infrared Reflection Absorption Spectroscopy
Authors: Hirano Shinya , Noda Hideyuki , Yoshigoe Akitaka , Gheyas Syed Irfan , Urisu Tsuneo
Published: October 2002

The structure of the H or D saturation adsorbed Si(100)1×1 surface generated at
400 K, and its change by annealing and synchrotron radiation (SR) irradiation were
investigated by infrared reflection absorption spectroscopy (IRRAS) using a CoSi2
buried metal layer (BML) substrate and reflection high-energy electron diffraction
(RHEED) measurements. On 650 K annealing, the D saturation adsorbed Si(100)1×1
surface changes to 2×1 structure consisting of only D-Si-Si-D, which gives rise to an
SiD stretching vibration band with a sharp, symmetric shape that peaked at around
1525 cm-1. If the SR irradiation is added to the annealing of the D saturation adsorbed
Si(100)1×1 surface, the shape of the SiD stretching vibration band at 1525 cm-1 after
650 K annealing becomes broad and asymmetric. This is explained by the fact that D-Si-D is etched (desorbed) by the SR irradiation.
Thin-Film Micromirror Array for High-Brightness Projection Displays
Authors: Hwang Kyu-Ho , Song Yong-Jin , Kim Sang-Gook
Published: October 2002

The thin-film micromirror array (TMA) is a new reflective-type light modulator that uses
thin film piezoelectric actuators in conjunction with micromirrors by surface micromachining
technology. The TMA optical system is designed based on Schlieren optics and the module is
fabricated by a conventional integrated circuit (IC) process. The design of the TMA has evolved
to enhance the optical performance as well as mechanical uniformity and electrical reliability.
The hidden actuator design TMA has a fill factor (FF) of over 90% and a module light
efficiency (MLE) of 65%. A working prototype of a video graphics array (VGA) format TMA
display system with three modules shows more than 7 lumen per watt light efficiency.
Fabrication of Microcantilever with a Silicon Tip Prepared by Anodization
Authors: Higa Katsuya , Asano Tanemasa
Published: October 2002

The fabrication process of a microcantilever with a silicon tip
prepared by anodization for an atomic force microscope(AFM) is
demonstrated. The silicon tip having a high aspect ratio can be
prepared using preferential anodization of a silicon wafer with
n/p junction. The microcantilever is fabricated by patterning a
silicon nitride film deposited on the anodized wafer. The silicon
tip is examined by observing the surface morphology of an
anisotropically etched silicon step and the grains of a vacuum
evaporated Au film.
New Fabrication Process of Single-Crystalline Silicon Islands Using Double Diffusion: Application to a Heating Resistor of a Thermal Inkjet Printhead
Authors: Lee Choon-Sup , Lee Jae-Duk , Han Chul-Hi
Published: October 2002

The n+-type silicon island was fabricated using double diffusion, selective anodization and oxidation of silicon. The island was applied as a heating resistor of a thermal inkjet printhead. The heating resistor has good uniformity of ±5% and good endurance of 108 cycles under electrical stresses. In the inkjet printhead structure, high-quality thermal oxide can be used as a passivation layer and a thick thermal barrier oxide under heating resistors can be easily achieved. The diameter of ejected ink dots with a nozzle diameter of 35 µm was about 100 µm. There were no satellites on the paper.
Hermetically Sealed Inductor-Capacitor (LC) Resonator for Remote Pressure Monitoring
Authors: Park Eun-Chul , Yoon Jun-Bo , Yoon Euisik
Published: October 2002

This paper reports an integrated inductor-capacitor (LC) resonator structure fabricated using bulk micromachining and anodic bonding technologies. In this resonator structure, pressure change monitored by a capacitive pressure sensor results in the change
of resonance frequency. The resonance frequency shift is detected by inductive coupling from an external transmission coil; therefore, pressure can be monitored remotely using the passive LC resonator. The fabricated device size measures
3 mm×3 mm×0.6 mm, and pressure responsivity has been estimated to be 2 MHz/mmHg. This micromachined, hermetically sealed structure is suitable for biomedical applications such as intraocular, cardiovascular and brain pressure monitoring.
Influence of Interface Structure on Chemical Etching Process for Air Gap of Microelectromechanical System Based on Surface Micromachining
Authors: Yoon Young Soo , Kim Joon Han , Polla Dennis. L. , Shin Young Hwa
Published: October 2002

This paper analyses the problems posed by the interface structure during
chemical etching by Hydro-fluoric (HF) acid for creating air gaps in
microelectromechnical system (MEMS) devices using PZT(53/47) films and
surface micromachining techniques. In order to investigate the influence of
interface structure on the HF chemical etching process,
Pt/PZT/Pt/Ti/TiO2/polysilicon/Si3N4/PSG/Si (Samples A and C) and Pt/PZT/RuO2/Ru/Si3N4/PSG/Si (Sample B) structures were fabricated. These structures
are selected for a microcantilever beam and/or an uncooled IR detectors
fabricated with PZT piezoelectric/pyroelectric films based on the surface
micromachining technique. Both need etching for the removal of phosphor
silicate glass (PSG) to create an air gap. If the devices had a poor interface
structure, they would fail during the HF chemical etching process because the
poor interface structure would act as a kind of penetration path for etching acid
leading to unwanted etching. Therefore, it is very important to investigate the
interface structure to fabricate efficient MEMS devices. In this study two
different solutions have been suggested to improve the interface structure. The
first is post thermal annealing at 900°C for 30 min. after deposition of
polycrystalline silicon for sample A. Secondly, a RuO2/Ru hybrid electrode was
deposited on Si3N4 directly instead of on the Pt/Ti/TiO2/Polysilicon electrode,
which has Pt/PZT/RuO2/Ru/Si3N4/PSG/Si as the device structure. These two
solutions suggest that a dense interface structure increases enhances of success
of the chemical etching process of MEMS devices fabricated using PZT films
and surface micromachining techniques.
Atomic Force Microscope Based Nanolithography of Self-Assembled Organosilane Monolayer Resists
Authors: Kim Jinchul , Oh Young , Shin HaiwonLee , SunwooPark SunwooPark
Published: October 2002

Atomic force microscope (AFM) has been used to investigate organosilane self-assembled
monolayer films (SAMs) for nanometer-scale lithography. The octadecyldimethylmethoxysilane monolayer as a resist was prepared on a Si substrate by using the immersion method.
Patterning was accomplished through the localized degradation of the monolayer as a result
of anodic reaction induced by an AFM tip. When the negative bias voltage was 10–30 V, the
protruding lines appeared in the exposed regions and the minimum linewidth was 70 nm.
The pattern fabricated on the monolayer was transferred to the Si substrate by chemical
etching in buffered oxide etch (BOE) solution. The etching proceeded area selectively in the
regions where the probe had passed, while the surrounding area remained unetched due to
the resistivity of the undegraded monolayer to the etching.
Coupling Characteristics of Semiconductor Coupled Quantum Dots in Coulomb Blockade Regime
Authors: Ishibashi Koji , Oosterkamp Tjerk H. , Hijman Remko V. , Kouwenhoven Leo P.
Published: October 2002

Coupled quantum dots in series have been realized in two dimensional electron
gas (2DEG) in GaAs/AlGaAs heterostructures using the surface gate, and transport
measurements have been performed at the dilution refrigerator temperature. The
electrical transport was found to be determined by the Coulomb blockade and the
resonant tunneling. The energy width of the resonant peak can be smaller than the
thermal energy when two dots are sufficiently isolated. The charge stability diagram, by
changing two gates attached to each dot, was measured for weak and strong coupling
conditions. The width of the current resonant peak changed significantly as the coupling
was increased, while the capacitive coupling did not change so much. The experimental
result was analyzed using a simple capacitance model.
Effects of Rapid Thermal Annealing on the Structural and Optical Properties of InAs/GaAs Self-Assembled Quantum Dots
Authors: Cho Shinho , Hyon Chan Kyung , Kim Eun Kyu , Min Suk-Ki
Published: October 2002

We present the effects of rapid thermal annealing on the structural and optical properties of InAs/GaAs self-assembled quantum dot structures grown by molecular beam epitaxy. Annealing at higher temperature results in an increase in island size, a corresponding decrease in the density of islands, and a redshift in the luminescence emission from the islands. The temperature dependence of the photoluminescence peak energy of the quantum dots for the unannealed and annealed samples is well described by the Varshni equation. The different values of thermal quenching activation energies for the unannealed and annealed samples indicate a variation of the quantum dot confining potential.
Fabrication of Periodic Si Nanostructure by Controlled Anodization
Authors: Nakagawa Takashi , Sugiyama Hisakazu , Koshida Nobuyoshi
Published: October 2002

It is demonstrated that anodization of heavily doped n-type silicon in the dark is available for producing periodic silicon nanostructures. The relationship between the porous silicon (PS) morphology and the anodization parameters have been investigated in detail using high resolution scanning microscopy. Analyses of mean valence during the dissolution process indicate that the straight periodic silicon nanostructure is formed under an appropriate condition corresponding to the transition region from ideal anodization to electropolishing mode. For producing more uniform periodic nanostructures, introduction of an external magnetic field during anodization is very effective. The experimental results show that controlled anodization is useful for periodic silicon nanofabrication.
Systematic Low Temperature Silicon Bonding using Pressure and Temperature
Authors: Li Y. Albert , Bower Robert W.
Published: October 2002

We have developed a systematic three-step process to low temperature direct bond silicon and/or SiO2 surfaces. The process activates the surface with ammonia, argon and oxygen plasma. While these activation processes allow a very strong low temperature bond to be created, they require techniques distinctly different from those found in previous work for reproducible results. The plasma processes do not result in a bond that propagates as a wave resulting from a point source initiation. A substantial pressure is required to initiate the bond. We have found that a three-step process using pressure and temperature results in very strong, reproducible bonds.
TiN Etching and Its Effects on Tungsten Etching in SF6/Ar Helicon Plasma
Authors: Choi Chang Ju , Seol Yeo Song , Baik Ki-Ho
Published: October 2002

Etching characteristics of TiN film have been investigated in SF6/Ar helicon plasma. The etch rate of TiN film increases with increasing source power, bias power and temperature, exhibits a maximum at a moderate pressure as a function of pressure. A possible mechanism of titanium fluoride formation is proposed based on the results of optical emission spectroscopy (OES). In order to determine the effect of titanium fluorides on tungsten etching, the loading effect in tungsten etchback is investigated as a function of source power, bias power and temperature. Using secondary ion mass spectrometry (SIMS), the relative concentrations of titanium fluorides redeposited on tungsten are measured by varying the bias power and temperature. The loading effect is reduced by enhancing the redeposition of titanium fluorides on a tungsten plug with increasing source and bias power. The loading effect is also retarded by lowering the temperature.
The Magnesium Diffused Layer Characteristics of a Lithium Niobate Single Crystal with Magnesium-Ion Indiffusion
Authors: Que Wenxiu , Lim Siakpiang , Zhang Liangying , Yao Xi
Published: October 2002

A Mg-ion indiffusion process was applied to lithium niobate single crystal substrates with a deposited magnesium oxide thin film. By means of electron probe microanalysis and X-ray diffraction analysis, the Mg concentration distribution along the depth of the magnesium diffused layer was obtained and the activation energy for Mg-ion indiffusion was determined to be 288 KJ/mol. It was also determined that the magnesium diffused layer exhibits a crystal structure of an unknown compound from the Mg–Li–Nb–O ternary system. It is proposed that this unknown compound and MgNb2O6, which form during a solid state reaction between the thin layer of MgO and the lithium niobate crystal in a Li2O-rich atmosphere, are the real sources for Mg-ion indiffusion into lithium niobate. The high activation energy and the appearance of this unknown compound in the magnesium diffused layer suggest that Mg-ions diffuse substitutionally into the lithium niobate crystal. Mechanisms causing a decrease in the refractive index of the Mg diffused layer are also discussed.
Microstructure of Polysilicon Films Grown by Catalytic Chemical Vapor Deposition Method
Authors: An-Qiang He An-Qiang He , Akira Heya Akira Heya , Nobuo Otsuka Nobuo Otsuka , Hideki Matsumura Hideki Matsumura
Published: October 2002

The catalytic chemical vapor deposition (cat-CVD), often called “hot-wire CVD”, is a new method of growing polycrystalline silicon (poly-Si) films at low temperatures. The microstructure of such cat-CVD poly-Si films is investigated by high-resolution transmission electron microscopy. The main microstructural features of these poly-Si films are nanometer-diameter columnar crystalline grains surrounded by a very thin amorphous phase. Good electrical properties, such as large carrier mobilities of the films, may be attributed to this microstructure.
Enhanced Growth of β-C 3N 4 Crystallites at a High Substrate Temperature
Authors: Chau-Nan Hong Chia-Yuan Hsu
Published: October 2002

The growth of β-C3N4 crystallites is studied at various
substrate temperatures by an inductively-coupled plasma sputtering
method
using 500 W of radio frequency power to enhance the gas dissociation.
The
crystallites deposited are demonstrated to be β-C3N4 phase
rather than other phases from the transmission electron diffraction and
the X-ray photoelectron spectroscopy results. Upon increasing the substrate
temperature from 400°C to 800°C,
β-C3N4
crystallite size increases from 0.02 µm to 0.2 µm, but the
[N]/[C] atomic ratio in the film decreases slightly from 1.0 to 0.85,
suggesting that the film contains larger β-C3N4 crystallites
in a less nitrogenated amorphous carbon matrix at a higher temperature.
The film deposited at 800°C exhibits a highly spotty
transmission
electron diffraction pattern and contains a high percentage (90%) of
sp
3 C-N bonding as estimated from X-ray photoelectron
spectroscopy.
The results suggest that a high substrate temperature enhances the
formation
of β-C3N4 crystallites at a high degree of gas
dissociation.
Fabrication and Characteristics of a Field Effect Transistor Using CdF 2/CaF 2 Heterostructures on a Si Substrate
Authors: Wataru Saitoh Wataru Saitoh , Katsuyuki Yamazaki Katsuyuki Yamazaki , Masafumi Tsutsui Masafumi Tsutsui , Atsushi Itoh Atsushi Itoh , Masahiro Asada Masahiro Asada
Published: October 2002

One-hundred-nanometre-long channel field effect transistors
using CdF2/CaF2 heterostructures on a Si substrate
were fabricated by molecular beam epitaxy growth
and electron beam lithography.
In these transistors, the gate was a highly doped Si substrate,
the gate insulator was a 5-nm-thick layer of CaF2,
the channel was a 5-nm-thick layer of CdF2,
and the source and drain were Au/Cr.
We observed effective modulation of the drain current with the
gate-source voltage at 16 K.
The drain current and the transconductance were
16 nA and 28 nS, respectively.
The operating voltage was high and the drain current was very
small due to the high potential barrier of the Schottky contact
at the source and drain electrodes.
Large Bandwidth Traveling-Wave Photodetectors on Semi-Insulating GaAs Substrate
Authors: Lee Jong-Chul , Taylor Henry F.
Published: October 2002

Photo-conductive traveling-wave photodetectors (TWPDs) in which
Coplanar Strip (CPS) transmission lines are adopted as electrodes are
suggested, fabricated on semi-insulating GaAs substrate, and
characterized in frequency domain. Symmetrical and asymmetrical CPS
types of electrodes are used and compared for photodetection
performance. High bandwidth of about 6.5–7.8 GHz and cut-off frequencies
of about 11.0–15.2 GHz are obtained.
Gain Spectrum Measurement of GaInAsP/InP Compressively-Strained Quantum-Wire Lasers
Authors: Takashi Kojima Takashi Kojima , Suguru Tanaka Suguru Tanaka , Hideo Yasumoto Hideo Yasumoto , Hiroyuki Nakaya Hiroyuki Nakaya , Shigeo Tamura Shigeo Tamura , Shigehisa Arai Shigehisa Arai
Published: October 2002

The gain spectral characteristics of 1.5 µm wavelength GaInAsP/InP compressively-strained quantum-wire lasers with a wire width of 20 nm and 25 nm, fabricated by electron beam lithography and 2-step
organometallic vapor phase epitaxial growth, were measured at a temperature of 100 K and were compared
with those of quantum-film lasers fabricated on the same wafer.
It was found for the first time that the material gain spectrum of quantum-wire lasers was narrower
than that of the quantum-film laser.
Characteristics of Material for Photoresist Spin Coating: Property for Reduction of Photoresist Consumption
Authors: Sanada Masakazu , Nakano Kayoko , Matsunaga Minobu
Published: October 2002

The spin coating property for the reduction of the photoresist consumption was
investigated experimentally using photoresist samples systematically. Dry film
thickness D is affected by spin velocity ω: D=kω-1/2, where k is a constant. The
photoresist samples can be characterized by a constant k irrespective of their
composition. The same k photoresist results in the same consumption when the prespin
velocity is optimized for reducing the consumption. The consumption is reduced as k
becomes smaller. In the case where the prespin velocity is fixed, the consumption
becomes smaller for the sample for which the solvent viscosity is small and the solvent
evaporation rate is large.
Variety Transformation of Compound at GaSb Surface under Sulfur Passivation
Authors: Lin Chuing L. , Su Yan K. , Se Than S. , Li Wen L.
Published: October 2002

An elemental Sb layer, formed at the oxide/GaSb interface, causes large surface
leakage current and recombination, which are two main drawbacks of GaSb-based
devices in full photoelectric application. The proportion of elemental Sb to other Sb
compounds at the GaSb surface was increased by immersing the sample into diluted
HCl solution. With sulfuring of the GaSb surface, elemental Sb was replaced by Sb2S5
and Sb oxides were removed. The mechanism that prevents formation of the leakage
path at the as-etched GaSb surface is elucidated by X-ray photoelectron spectroscopy
(XPS).
Photoluminescence and Electroluminescence in Polymer Mixture of Poly(alkylphenylacetylene) and Poly(diphenylacetylene) Derivatives
Authors: Rahmat Hidayat Rahmat Hidayat , Masaharu Hirohata Masaharu Hirohata , Kazuya Tada Kazuya Tada , Masahiro Teraguchi Masahiro Teraguchi , Toshio Masuda Toshio Masuda , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Photoluminescence (PL) and electroluminescence (EL) in polymer mixture of blue emissive poly(1-hexyl-2-phenylacetylene) (PHxPA) and green emissive poly(1-phenyl-2- p -n-butylphenylacetylene) (PDPA-nBu) were studied. Both PL and EL in the polymer mixture change from blue to green by the addition of a small amount of PDPA-nBu into PHxPA. This fact has been interpreted as a result of energy transfer from the larger band gap PHxPA to the smaller band gap PDPA-nBu. PL and EL in the polymer mixture are found to be deconvoluted into PL1 and PL2 peaks originating from PDPA-nBu and PHxPA, respectively. PL1 of PDPA-nBu shifts to a higher energy upon introduction of PHxPA, while PL2 of PHxPA also shifts to a higher energy by adding a small amount of PDPA-nBu. From this change in luminescence, molecular conformation at the excited state in the mixture is interpreted to be distorted, depending on the molar ratio of PDPA-nBu and PHxPA. A similar change in PL and EL spectra with molar ratio implies that in this mixture the energy relaxation process is nearly the same for both the cases and does not strongly depend on whether the excited state is produced by photoexcitation or charge injection.
Simultaneous Observation of SiO2 Surface and SiO2/Si Interface Using Self-Assembled-Monolayer Island
Authors: Komeda Tadahiro , Namba Kenji , Nishioka Yasushiro
Published: October 2002

Steps on SiO2 surface and in SiO2/Si interface, which remain on the surface after the formation of SiO2 on atomically flat Si(111) surface, are simultaneously observed with a novel use of self-assembled-monolayer (SAM) islands. After the formation of octadecyltrichlorosilane (OTS) SAM islands on SiO2, SiO2 layers in the area which are not covered by OTS-SAM are completely removed by hydrofluoric acid (HF) to expose SiO2/Si interface, followed by atomic-force-microscopy (AFM) observation. OTS-SAM islands trace the morphology of SiO2 surface underneath, whose structure is preserved even after being dipped into HF. The results indicate that the steps on SiO2 and in the interface of SiO2/Si show no lateral shift, which suggests no step-flow during oxidation for stress relief.
First-Principles Approach to the Effect of c-axis Elongation of BaTiO 3 Thin Films
Authors: Tatsuo Schimizu Tatsuo Schimizu , Takashi Kawakubo Takashi Kawakubo
Published: October 2002

The effect of c-axis elongation in the tetragonal phase of perovskite BaTiO3 (BTO) thin films was investigated using the first-principles method with ultrasoft pseudopotentials. The total energy E

P
, with the relaxation of the internal atoms' positions Ratom as a function of the lattice constant of the c-axis c, was drastically lowered by the polarization, i.e., the long-range dipole-dipole interaction, compared with the total energy E
NP without the relaxation of Ratom. The tensile elastic deformation in the direction of the c-axis was found to become much easier, due to the polarization. Changing of ferroelectric properties via the lattice constant c was also considered by investigating the distance between the Ti atom and the apex O atom as a function of the lattice constant c. Moreover, the polarizations were approximately estimated as a function of the lattice constant c utilizing the Born dynamical effective charge obtained by Axe for cubic BTO.
Electrical Characteristics of CO2-Sensitive Diode Based on WO3 and IrO2 for Microsensor Applications
Authors: Chao Shuchi
Published: October 2002

Devices based on the contact of sputtered WO3 and IrO2 that are covered by an HCO3
--containing polymer exhibit reversible and reproducible CO2-dependent, diodelike current rectification at 1 atm and room temperature. The gain or loss of current in the forward direction as a function of CO2 concentration is found to be tunable by controlling the thickness ratio of the WO3 and IrO2 films. The rectification mechanism is uniquely governed by the thermodynamic free energies; this is the key to the durability previously not attainable using conventional diodes in microsensor applications. These diodes are useful as a basis of construction for durable microsensors operating in gases or liquids.
Growth of GaN on Indium Tin Oxide/Glass Substrates by RF Plasma-Enhanced Chemical Vapor Deposition Method
Authors: Park Doo-Cheol , Ko Hyun-Chul , Fujita Shizuo , Fujita Shigeo
Published: October 2002

The GaN thin films were grown at a low substrate temperature (500°C) by radio-frequency (13.56 MHz) plasma enhanced chemical vapor deposition (RF PECVD) on glass substrates deposited with indium tin oxide (ITO) thin films. The growth of a thin buffer layer at 200°C improved the sample quality. Highly oriented polycrystalline GaN, where the (0002) planes were parallel to the substrate surface, was identified by X-ray diffraction (XRD) measurement. The surface orientation was strongly dependent on the growth parameters. Surface morphology observed by atomic force microscopy (AFM) showed the hexagonal columnar structure of the GaN thin films.
Low Temperature Deposition of TaCN Films Using Pentakis(diethylamido)tantalum
Authors: Jun Gyu-Chang , Cho Sung-Lae , Kim Ki-Bum , Shin Hyun-Kook , Kim Do-Heyoung
Published: October 2002

Ta(CN) films were thermally deposited at low temperature (≤400°C) using single source pentakis(diethylamido)tantalum (PDEAT) as a precursor. The activation energy of the surface reaction is about 0.79 eV and the maximum deposition rate obtained is about 100 Å/min at 350°C. The resistivity of the as-deposited film decreases as the deposition temperature increases and the minimum value of resistivity obtained is 6000 µ Ω-cm for the sample deposited at 400°C. There is no aging effect of the film resistivity after air exposure. Major chemical elements in the films are identified as Ta, C, and N with some amounts of O by Auger electron spectroscopy (AES). Most of the carbon elements in the film is identified as bonded to Ta by X-ray photoelectron spectroscopy (XPS). The microstructural investigation using high resolution transmission electron microscopy (HRTEM) reveals a nanocrystalline phase with an average grain size of about 30 Å.
High External Quantum Efficiency of Electroluminescence from Photoanodized Porous Silicon
Authors: Nishimura Kohsuke , Nagao Yasuyuki , Ikeda Noriaki
Published: October 2002

Porous silicon (PS) light emitting diodes (LEDs) were fabricated from p+n Si wafers by photoanodization. The maximum external quantum efficiency (ηext) of electroluminescence (EL) from PS-LED up to 0.8%, which is the highest ever reported for PS-LEDs with solid state contact, was achieved under pulsed operation with 1% duty in ambient air. However, we found that PS-LED with a high ηext was accompanied by the problem of high series resistance.
High-Power, Long-Lifetime InGaN/GaN/AlGaN-Based Laser Diodes Grown on Pure GaN Substrates
Authors: Nakamura Shuji , Senoh Masayuki , Nagahama Shin-ichi , Iwasa Naruhito , Yamada Takao , Matsushita Toshio , Kiyoku Hiroyuki , Sugimoto Yasunobu , Kozaki Tokuya , Umemoto Hitoshi , Sano Masahiko , Chocho Kazuyuki
Published: October 2002

Epitaxially laterally overgrown GaN on sapphire was used to reduce the number of threading dislocations originating from the interface of the GaN epilayer with the sapphire substrate. The GaN layer above the SiO2 mask area surrounding the window, corresponding to the lateral overgrowth, was nearly free of the threading dislocations. A high density of threading dislocations was observed in the vicinity of GaN grown in the window regions. InGaN multi-quantum-well-structure laser diodes (LDs) grown on pure GaN substrates, which were fabricated by removing the sapphire substrate, were demonstrated. The LDs with an output power of 5 mW exhibited a lifetime of more than 290 h and an estimated lifetime of 10,000 h despite a relatively large threshold current density. The far-field pattern of the LDs with a cleaved mirror facet revealed single-mode emission without any interference effects.
Picosecond Synchronous Electro-Optic Sampling with a Jitter-Reduced Gain-Switched Laser Diode
Authors: Sahri Nabil , Nagatsuma Tadao , Yaita Makoto , Shimizu Naofumi
Published: October 2002

Jitter reduction technique for gain-switched DFB lasers using continuous-wave light injection has been successfully used for the first time for electro-optic sampling in the synchronous sampling scheme. This technique enables picosecond time resolution together with low and tunable sampling rate. Its effectiveness is demonstrated by measuring the switching time of resonant tunneling diodes.
In-Diffusion and Isothermal Annealing of Iron-Related Defects in Czochralski N-Type Silicon
Authors: Shuji Tanaka Shuji Tanaka , Hajime Kitagawa Hajime Kitagawa
Published: October 2002

Electrically active iron-related defects in Czochralski (CZ) n-type silicon have been studied using deep level transient spectroscopy (DLTS) and the Hall effect. Iron-related defects observed in CZ n-type silicon are identical to those in floating zoned (FZ) n-type silicon. These observed defects can be related to complexes, including iron atoms.
The Complex Propagation Constant of Thin Metal Films Surrounded with Dielectric Media: a Simple Technique
Authors: Tseng Shiao-Min , Zhan Jing-Hong
Published: October 2002

The propagation constants of surface-plasmon modes in a structure comprised of a thin metal film surrounded with dielectric media on which an evanescent field is incident are analyzed and numerically calculated. The solution corresponds to zero reflection of the incident light wave. The calculated results agree with those obtained from the dispersion relationship in the waveguide. A coupled waveguiding structure consisting of two metal films is presented and the advantages of our technique are discussed.
Anisotropic Polarization Properties of Photoluminescence from GaInAsP/InP Quantum-Wire Structures Fabricated by Two-Step Organometallic Vapor Phase Epitaxy Growth
Authors: Kojima Takashi , Shigehisa Arai and Gerd U. Bacher Shigehisa Arai and Gerd U. Bacher
Published: October 2002

The polarization dependence of 1.5µm wavelength GaInAsP/InP quantum-wire structures fabricated by electron beam lithography and two-step organometallic vapor phase epitaxy growth were measured and compared with quantum-film structures fabricated on the same wafer. As a result, clear anisotropic photoluminescence (PL) properties of the quantum-wire structure corresponding to the wire width (25 nm and 35 nm) were confirmed. This anisotropy was observed to be slightly stronger in the 1% compressively-strained quantum-wire structure than that in the lattice-matched one with the same wire width (35 nm).
A Theoretical Investigation of the Potential for Inter-Surface Migration of Ga Adatoms between GaAs(001) and (111)B Surfaces
Authors: Ito Tomonori , Shiraishi Kenji , Kageshima Hiroyuki , Suzuki Yasuo Y.
Published: October 2002

The potential for inter-surface migration of Ga adatoms between GaAs(001)-(2×4)
and GaAs(111)B-(√19×√19) or -(2×2) is theoretically investigated. We
used empirical interatomic potential and an energy term as a function of the
number of electrons remaining in the Ga dangling bonds. The calculated results
indicate that the lattice sites on the (001)-(2×4)β2 surface are more favorable
for Ga adatoms than those on the (111)B-(√19×√19) and -(2×2) surfaces. This
is because the formation of Ga–Ga dimers in the missing dimer rows on the
(001)-(2×4)β2 surface suppresses the number of electrons remaining in the Ga
dangling bonds. These results suggest that Ga atoms favorably adsorb on the
(001) top surface and that Ga atoms impinging on the (111)B side surface
basically diffuse to the (001) top surface so long as both top and side surfaces
are single-domain structures. This conclusion is consistent with some aspects of
other experimental studies.
Empirical Interatomic Potentials for Nitride Compound Semiconductors
Authors: Ito Tomonori
Published: October 2002

Empirical interatomic potentials are determined for nitride compound
semiconductors such as AlN, GaN and InN. The versatility of these
empirical potentials is confirmed by the calculation of elastic constants for
AlN, GaN and InN, and by the calculation of excess energies for various
monolayer superlattices. The results compare favorably with available
results experimentally and empirically. These empirical potentials for
nitride compound semiconductors are as accurate as those already existing
in the literature for semiconductors.
Phonon Softening and Time Dependence of Elastic Peak Appearing Prior to the Martensitic Transformation in Au–47.5 at%Cd
Authors: Ohba Takuya , Raymond Stephane , Shapiro Stephan M. , Otsuka Kazuhiro
Published: October 2002

There are two distinct martensites called γ2
′ and ζ2
′ phases near the equi-atomic composition in AuCd alloy system. The phonon dispersion relation of the [ζζ0]TA2 branch was measured by inelastic neutron scattering in a Au52.5Cd47.5 alloy which produces γ2
′ martensite. The difficulty of strong neutron absorption was overcome by the use of an isotope 114Cd. The softening was observed at the Brillouin zone boundary and at ζ=0.35. An elastic peak was observed at ζ=0.35, but not at the zone boundary. The peculiar time dependent behavior was observed in the elastic peak.
Increased Catastrophic-Optical-Damage Output Power for High-Power Semiconductor Lasers Coated with High-Refractive-Index Films
Authors: Ueno Yoshiyasu
Published: October 2002

Mirror facet coating with a high-refractive-index film such as TiO2 and Ta2O5 is proposed to obtain
high-power short-wavelength semiconductor lasers. A drastic increase in the output power attainable before
catastrophic optical damage occurs is theoretically predicted for such a laser without the need to decrease facet
reflectivity. This increase is shown to originate from destructive interference of laser light fields in the vicinity of
the coated mirror facet when the film's refractive index is larger than the square root (≈1.8–1.9) of the laser's effective refractive index.
Improvement in Ba 1-xKxBiO 3 Grain Boundary Junctions by Ar + Beam Irradiation
Authors: Yukihiko Wada Yukihiko Wada , Tetsuya Takami Tetsuya Takami , Ken'ichi Kuroda Ken'ichi Kuroda , Tatsuo Ozeki Tatsuo Ozeki
Published: October 2002

To control the normal resistance of Ba1-x
KxBiO3 (BKBO) artificial grain boundary
junctions, the influence of Ar+ beam irradiation on BKBO junctions on MgO (100) bicrystal
substrates was investigated. Contrary to our expectation, the properties of all junctions were
found to be improved. In the most marked changes, the critical current density increased from
2.3 kA/cm2 to 31 kA/cm2, while the normalized junction resistivity decreased from
1.4 × 10-6 Ω·cm2 to 1.4 × 10-7 Ω·cm2.
No change was observed in the gap voltages and the critical current density of the BKBO films.
Translational Energy Distribution of CO Produced in Infrared-Laser-Assisted Reaction of O2 with a Graphite Surface
Authors: Kamioka Isao , Izumi Keisuke , Kitajima Masahiro , Kawabe Takaya , Ishioka Kunie , Nakamura Kazutaka G.
Published: October 2002

Infrared-laser-assisted reactions of O2 with a graphite surface were studied with laser-ionization mass spectroscopy. CO was observed as a reaction product of O2 and graphite. A time profile of CO was measured for the first time, and the mean translational temperature of CO was measured to be 790±80 K. The translational temperatures of carbon clusters of C, C2 and C3 evaporated from the surface were also measured.
A Double-Layer Polymer/Liquid-Crystal Grating with Polarization Direction-Independent Diffraction Properties
Authors: Wen-Tao He Wen-Tao He , Toshiaki Nose Toshiaki Nose , Susumu Sato Susumu Sato
Published: October 2002

A novel liquid crystal (LC) grating with polarization direction-independent diffraction properties is proposed. This LC grating consists of two polymer/LC layers with a periodic relief structure. The two layers have good homogeneous alignment and orthogonal to each other. The double-layer polymer/LC grating can be fabricated by a simple single-step process with UV irradiation. The diffraction intensity of the LC grating can be controlled by the applied voltage and the diffraction properties are not polarization-direction dependent.