bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Homologous Impurity on the Solid-Solid Phase Transition of Normal-Alkane (Hexatriacontane) Crystal Studied by Time-Resolved X-Ray Measurements
Authors: Forhad Mina Mohammad , Tsutomu Asano Tsutomu Asano , Ratno Nuryadi Ratno Nuryadi , Chie Sawatari Chie Sawatari , Hiroshi Takahashi Hiroshi Takahashi , Ichiro Hatta Ichiro Hatta
Published: October 2002

The effect of impurities on the solid-solid phase transition of solution-grown normal-alkane (hexatriacontane) crystals was investigated using differential scanning calorimetry (DSC), time-resolved small-angle X-ray scattering (SAXS) and polarizing microscopy. Normal-dotriacontane was used in this work as a homologous impurity. Six kinds of crystals were grown using two different solution concentrations (S
C) and three kinds of impurity fractions (I
F). DSC results show that the temperature of the solid-solid phase transition decreases with I
F and S
C. Time-resolved SAXS measurements exhibit a dynamic change of the solid-solid phase transition where the onset temperature of the transition is also lowered by I
F and S
C. A streak-like pattern which was apparent in the low-angle scattering clarifies that flat-shaped defects parallel to the lamellar surface increase with I
F and S
C. The transition frontier observed by polarizing microscopy indicates that molecules of more than 104 lamellae cooperatively accompany the solid-solid phase transition. The onset temperature as measured by SAXS is more than 1°C higher than that measured by DSC. The deviation is explained by the time lag for growing the bulk (secondary) nucleation from local (primary) nucleation sites of the solid-solid phase transition.
Kinetic Crystallization Behavior of Phase-Change Medium
Authors: Chiang Donyau , Jeng Tzuan-Reng , Huang Der-Ray , Chang Yung-Yuan , Liu Chung-Ping
Published: October 2002

The crystallization behavior of nominal-composition GeSb2Te4films prepared by rf-magnetron sputtering are examined. The crystal structures of the as-sputtered and the annealed films at different annealing temperatures are identified by the X-ray diffraction (XRD) method. Two phase transformations occur in the conventional slow heating process when the as-sputtered film is heat-treated from the ambient temperature to its melting point. However, only the amorphous to face-centered cubic (FCC) transformation is allowed when laser annealing with a 1011°C/min heating rate is applied to heat the films. Consequently, we predict that the meta stable FCC phase, instead of the hexagonal closed-packed (HCP) phase, is the dominant crystalline phase in the GeSb2Te4phase-change recording medium.
Initialization Characteristics and their Effects on the Erasabilty of Phase Change Optical Disks Using Transmission Electron Microscopy
Authors: Chen Huang-Wen , Hsieh T. E. , Liu Jia-Reuy , Shieh Han-Ping D.
Published: October 2002

We investigated the microstructure of phase change optical disks
subjected to various initialization conditions using transmission
electron microscopy (TEM). The effects of initialization powers on
the erase ratio of phase change optical disks and corresponding
microstructure changes were also studied. It was found that the
increase of initialization power enlarged the width of the
recrystallization band formed in the recording media of the disk. A
wide recrystallization band was effective for decreasing the
residual signal level hence the erase ratio increased. Disk dynamic
test and TEM study results also revealed the deterioration of
carrier-to-noice ratio (CNR) characteristic and the increasing trend
of erase ratio was reduced when a substantial amount of coarse
grains appeared in the crystalline region. This elucidates the
necessity for phase change optical disks to have good heat
dissipation property in order to suppress the formation of coarse
granular structures.
Electron-Electron Interaction Effects in Sb–Te–Ag Phase-Change Media
Authors: Wu Chih Yuan , Yao Yeong Der , Song Yu Lin , Huang Der-Ray
Published: October 2002

We have measured the electrical resistivity of (Sb2Te3)1-x
Agx
phase-change media (0.13 ≤x ≤0.21)
between 2 and 15 K, in order to investigate the occurrence of temperature
and disorder dependent correction, Δρ(T,ρr), to the
residual resistivity in a disordered system. As the temperature T is
lowered to the liquid helium temperature, a resistivity rise
Δρ/√T ∼-ρr
2.5 is observed.
This functional form is due to the enhanced electron-electron interaction
effects in a disordered metal. Our experimental results completely support
the theoretical predictions, i.e.
Δρ(T) ∼- √Tρr
2.5.
Thermally Optimum Structure for Overwriting Cyclability and Cross-Erase Characteristics
Authors: Lee Kyung-Geun , Yoon Du-Seop , Kim Sung-Su , Roh Myung-Do , Whang In-O , Park Chang-Min , Kim Yoon-Gi , Park Seung-Han
Published: October 2002

As two key restrictions for increasing the recording capacity, cross-erase and jitter
from narrowing track pitch (0.55 µm–0.6 µm) and making small marks (0.40 µm–0.62 µm) are
presented using a thermally optimum phase-change optical disk with the ability of thermal
endurance and high thermal conduction as well as minimum crosstalk and maximum groove signals.
For overwriting jitter no increase after 104 cycles is observed. The cross erase after 104
overwriting cycles resulted in less than 1% of jitter increase from the initial value.
High-Density Phase-Change Optical Disc with Low-to-High Signal Direction
Authors: Nakamura Naomasa , Morishita Naoki , Suzuki Katsumi , Yusu Keiichiro , Ashida Sumio , Kikitsu Akira , Ichihara Katsutaro
Published: October 2002

High-density recording capability has been demonstrated in a modified low-to-high type
phase-change disc which consists of multilayered lower dielectric film and an AlN upper
protective layer. The thermal simulation shows that the disc is effective for decreasing
thermal interference. A carrier to noise ratio (CNR) of more than 52 dB and an overwriting
erase ratio of more than 30 dB were obtained at a bit length of 0.28 µm and a track pitch of
0.6 µm on both land and groove at a linear velocity of 8.2 m/s.
Chromatic Correction of High-Performance Solid Immersion Lens Systems
Authors: Milster Tom D.
Published: October 2002

The chromatic dispersion of hyper-hemisphere solid immersion lens (SIL) systems is discussed. A
simple correction mechanism using a diffractive optical element (DOE) is presented that improves
the chromatic aberration by a factor of ten.
Analysis of Device Characteristics for InGaN Semiconductor Lasers
Authors: Gen-ichi Hatakoshi Gen-ichi Hatakoshi , Masaaki Onomura Masaaki Onomura , Shinji Saito Shinji Saito , Katsunobu Sasanuma Katsunobu Sasanuma , Kazuhiko Itaya Kazuhiko Itaya
Published: October 2002

Carrier overflow and perpendicular transverse mode in InGaN multi-quantum-well lasers have been analyzed by numerical calculation. A high acceptor concentration for the p-type cladding layer and the reduction of the active layer volume have a large effect on the reduction of carrier overflow. Anti-guide-like behavior of the waveguide mode is formed in InGaN laser structures where the cladding layers have insufficient thickness. The layer structure should be designed so as to reduce the carrier overflow and suppress the anti-guide-like mode.
4.7 GB Phase Change Optical Disc with In-Groove Recording
Authors: Masataka Yamaguchi Masataka Yamaguchi , Takahiro Togashi Takahiro Togashi , Satoshi Jinno Satoshi Jinno , Hideo Kudo Hideo Kudo , Eiji Muramatsu Eiji Muramatsu , Shoji Taniguchi Shoji Taniguchi , Akiyoshi Inoue Akiyoshi Inoue
Published: October 2002

We developed a rewritable optical disc with 4.7 GB/side capacity as an extension of the digital versatile disc recordable (DVD-R) system.
The disc is readily playable on a read-only DVD player or a DVD-ROM drive with a small firmware modification.
As far as the fundamental characteristics of the disc which adopts an in-groove recording are concerned, the reflectivity is 18% or more, modulated amplitude is 60% or greater, and jitter is 8% or less.
As we had sufficient differential phase detection (DPD) tracking error signals from the recorded disc, we think the DPD tracking method is practical.
These results cleared the single-layer DVD-ROM specifications except for the reflectivity.
The measured reflectivity satisfies the specifications of the dual-layer DVD-ROM disc.
Furthermore we confirmed that the recorded disc was playable on a blue laser playback system.
Investigation of the Oxidation State of Fe in Stoichiometric Fe:LiNbO3 for Digital Holographic Recording
Authors: Hideki Hatano Hideki Hatano , Takashi Yamaji Takashi Yamaji , Satoru Tanaka Satoru Tanaka , Yasunori Furukawa Yasunori Furukawa , Kenji Kitamura Kenji Kitamura
Published: October 2002

We investigated the oxidation state of Fe in stoichiometric LiNbO3 (SLN) in comparison with congruent LiNbO3 (CLN) from the viewpoint of digital holographic data storage. The dual oxidation states (Fe2+ and Fe3+) were controlled by changing Fe-doping levels and thermal annealing conditions after growth. We found that the photorefractive (PR) sensitivity of SLN under extraordinary polarization is more than 50% higher than that of CLN, which is more than 10 times higher than that of CLN under the generally used ordinary polarization. This high performance in PR sensitivity can be explained by the increased Pockels constant and photoconductivity. We could demonstrate high performance digital recording with fast writing speed and low bit-error rate using stoichiometric LiNbO3 under extraordinary polarization. We also observed that SLN showed a smaller erasure time constant than that of CLN because of increased photoconductivity. Consequently, the “M/# value” was almost the same as that of CLN. The M/# value is the metric for multiplexing and is proportional to the product of PR sensitivity and erasure time constant.
Light-Induced Surface Modification of Urethane-Urea Copolymer Film Used as Write-Once Optical Memory
Authors: Yoshimasa Kawata Yoshimasa Kawata , Yasuo Aoshima Yasuo Aoshima , Chikara Egami Chikara Egami , Masahiko Ishikawa Masahiko Ishikawa , Okihiro Sugihara Okihiro Sugihara , Naomichi Okamoto Naomichi Okamoto , Masaaki Tsuchimori Masaaki Tsuchimori , Osamu Watanabe Osamu Watanabe
Published: October 2002

We report the surface modification of urethane-urea copolymer
film by illumination with light in the blue region. Since this type
of film does not require any development processes and the
modification is irreversible and thermally stable, this material is
expected to be the medium used in write-once optical memory. The
light intensity required for the surface modification and the thermal
stability of the recorded data are discussed.
Development of a Sessile Drop Method Concerning Czochralski Si Crystal Growth
Authors: Sakai Susumu , Huang Xinming , Okano Yasunori , Hoshikawa Keigo
Published: October 2002

A sessile drop method for the measurement of the oxygen dissolution rate from silica glass to silicon melt proposed previously has been further developed. The main error in the measurement was the weight loss of the silica plate itself because of the reaction between the silica plate and the carbon crucible. A pyrolytic boron nitride (PBN) plate was placed between the silica plate and carbon crucible, and results showed that the error was reduced effectively using the protective PBN plate. As an application of the sessile drop method, the effect of OH content in different silica materials on the oxygen dissolution rate was also investigated. There was no evident difference in the dissolution rate from the different kinds of silica materials with different OH concentrations.
X-Ray Analysis of In Distribution in Molecular Beam Epitaxy Grown InGaAs/GaAs Quantum Well Structures
Authors: Shingo Fujimoto Shingo Fujimoto , Mitsuru Aoki Mitsuru Aoki , Yoshiji Horikoshi Yoshiji Horikoshi
Published: October 2002

GaAs/InGaAs/GaAs quantum well structures grown on GaAs (001) by molecular beam epitaxy (MBE) at substrate temperatures between 450°C and 540°C are investigated using X-ray diffraction (XRD) techniques. As the substrate temperature increases, the diffraction peak angles of InGaAs shift to the lower In composition side, and the integrated diffraction spectrum of the InGaAs peaks weighted by composition x decreases. By assuming a constant segregation rate, we estimate the In desorption and segregation rates, and determine the In distribution profiles of the quantum well structures.
Equilibrium Phase Diagrams for Stranski-Krastanov Structure Mode of III–V Ternary Quantum Dots
Authors: Nakajima Kazuo
Published: October 2002

The strain, surface and interfacial energies of III–V ternary systems were
calculated for three kinds of structure modes: the Frank-van der Merwe (FM) mode, the
Stranski-Krastanov (SK) mode and the Volmer-Weber (VW) mode. The free energy for
each mode was estimated as functions of the thickness and composition or lattice misfit.
Through comparison of the free energy of each mode, it was found that the thickness-composition phase diagrams of III–V ternary systems can be determined only by
considering the balance of the free energy and three kinds of structure modes appear in the
phase diagrams. The SK mode appears only when the lattice misfit is large and/or the
lattice layer is thick. The VW mode appears when the lattice misfit is large and the lattice
layer is thin and only in the InPSb/InP and GaPSb/GaP systems which have the largest
lattice misfit of III–V ternary systems. The stable region of the SK mode in the
GaPSb/GaP and InPSb/InP phase diagrams is largest of all because the composition
dependence of the strain energy of these systems is stronger than that of the other systems. The critical number of lattice layers below which two-dimensional (2D) layers precede the
three-dimensional (3D) nucleation in the SK mode at x=1.0 depends on the lattice misfit.
In the InPSb/InP system, the smallest number of 2D layers precede the 3D nucleation in
the SK mode.
Large Negative Magnetoresistance in Thin Films of Magnetic Material Bi2-xPbxSr3Co2O9
Authors: Tsuyoshi Yamamoto Tsuyoshi Yamamoto , Ichiro Tsukada Ichiro Tsukada , Kunimitsu Uchinokura Kunimitsu Uchinokura
Published: October 2002

We have studied the effect of Pb substitution on the transport
properties of nonmagnetic layered cobalt-oxide
Bi2Sr3Co2O9 prepared by the
molecular beam epitaxy technique. All the films were prepared
on YAlO3 (001) and Nd:YAlO3 (001)
substrates in the presence of pure ozone. The film without Pb substitution
shows a highly insulating behavior.
Pb substitution makes the film more conductive
and increases its c-axis length.
The most striking effect of Pb substitution is the appearance of
large negative magnetoresistance typically below 10 K.
We propose that this material can be used in the fabrication of a
Bi2Sr2Ca
n-1CunO4+2n+δ-based
functional device.
Charge Trapping Sites in Spherulitic Polypropylene
Authors: Yagishita Akihiko , Yamanouchi Hiroko , Ikezaki Kazuo
Published: October 2002

Charged areas of spherulitic polypropylene (PP) samples were visualized by a simple technique
of attaching oppositely charged fine dye particles. A combination of this visualization technique and
thermally stimulated current (TSC) spectroscopy was applied to identify the regions where shallow
and deep charge traps exist densely in positively corona-charged spherulitic PP. The shallow and
deep traps in the PP sample are directly related to its two TSC bands, BL and BH, appearing at
temperatures around 60°C and above 100°C, respectively. From visualized charge patterns of the
PP samples with and without thermal cleaning of the BL band, it was found that the shallow traps
mainly exist in the boundaries and the peripheral regions of spherulites while the deep traps are
located in the central parts. Furthermore, the relative numbers of the shallow and the deep traps in
the PP spherulites were estimated and found to depend on spherulite size: the ratio of shallow to deep
traps decreased from 60/40 for 130–190 µm spherulites to 43/57
for 320–400 µm spherulites.
Depolarized Light Scattering of Liquid Crystals with Addition of Carbon Tetrachloride in the Isotropic Phase
Authors: Shibata Tetsuya , Matsuoka Tatsuro , Nomura ShinobuKoda
Published: October 2002

The temperature dependence of the translational and reorientational
coupling parameter “R” of liquid crystals, 4-cyano-4′-penthylbiphenyl
(5CB) and p-methoxybenzylidene-n-butylaniline (MBBA) in the
isotropic phase was obtained as a function of the concentration of diluent
carbon tetrachloride from the polarized and depolarized Rayleigh light
scattering spectra. A difference in temperature dependence of R for
MBBA-CCl4 and 5CB-CCl4 mixtures near the isotropic-nematic phase
transition point was observed. The coupling parameter R at temperatures
high above the transition point decreased rapidly with the concentration of
diluent.
Design of Radial Line Slot Antennas at 8.3 GHz for Large Area Uniform Plasma Generation
Authors: Yamamoto Tetsuya , Chien Nguyen Thang , Ando Makoto , Goto Naohisa , Hirayama Masaki , Ohmi Tadahiro
Published: October 2002

A radial line slot antenna (RLSA) 400 mm in diameter is designed for a plasma source at 8.3 GHz
as a candidate for a large area high density plasma source with a narrow process space. A RLSA
with paired slots arrayed concentrically on its aperture is designed and applied to a plasma process
system which does not need a magnetic field. First, electrical performance without plasma is
predicted and measured. Reasonable voltage standing wave ratio (VSWR) as well as uniform field
distribution on the antenna aperture is realized. As applied to the plasma test equipment, high
electron density of more than 1×1012 cm-3 as well as fairly uniform (±2%) distribution at a low
electron temperature is produced in the vicinity of the antenna aperture through a quartz glass
window. Control of uniformity in ion flux profiles by blocking the
antenna aperture is demonstrated.
Influence of Sputtering Parameters on the Formation Process of High-Quality and Low-Resistivity HfN Thin Film
Authors: Satoko Shinkai Satoko Shinkai , Katsutaka Sasaki Katsutaka Sasaki
Published: October 2002

We have investigated the influence of sputtering parameters such as N2 flow ratio, applied dc power and substrate temperature on the formation process of high-quality and low-resistivity HfN film using an ultrahigh-vacuum sputtering system. The obtained film quality was evaluated using X-ray diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses. The resistivity values were measured by a four-point probe method. We found that (111) HfN and (100) HfN films with equivalent resistivity to the bulk value can be grown in a single-oriented state at the substrate temperature of 450°C on (111) Si and (001) Si, respectively. Therefore, it is revealed that impurity-free, high-quality HfN film with high crystallinity and low resistivity can be obtained at relatively low substrate temperatures, if appropriate sputtering conditions are satisfied, using an ultrahigh-vacuum sputtering system.
Effectiveness of Al12W Layer on Suppression of Spontaneous Reaction in Al/Al12W/W2N/Si Contact Systems
Authors: Takeyama Mayumi B. , Noya Atsushi
Published: October 2002

The effectiveness of the interposed Al12W layer in realizing a thermally stable Al/Al12W/W2N/Si contact was examined by varying its thickness. It was revealed that an interposed Al12W layer whose thickness is greater than the diffusion length of the species that participates in the spontaneous reaction of the Al12W formation upon annealing was required to realize a thermally stable interface in the contact. The effectiveness of the interposed Al12W layer depended on the kinetics of the spontaneous reaction between Al and W in the contact.
Atomic Force Microscopy Observation of Deoxyribonucleic Acid Stretched and Anchored onto Aluminum Electrodes
Authors: Masanori Ueda Masanori Ueda , Hiroshi Iwasaki Hiroshi Iwasaki , Osamu Kurosawa Osamu Kurosawa , Masao Washizu Masao Washizu
Published: October 2002

We have demonstrated that the electrostatic stretch-and-positioning of Deoxyribonucleic Acid (DNA) is useful for the analysis of a long DNA molecule by means of atomic force microscopy (AFM). Using a pair of aluminum electrodes patterned on a glass plate, DNA molecules were stretched parallel to the field line, and immobilized onto the electrodes. Through AFM observation of avidin-labeled DNA, we confirmed the immobilization of individual DNA molecules, not aggregates.
Energy Barrier Height for Electron Injection in Organic Electroluminescent Devices with Dithienosilole
Authors: Adachi Akira , Ohshita Joji , Kunai Atsutaka , Okita Koichi
Published: October 2002

We have investigated the relationship between electroluminescent (EL) device
performance and electron injection properties on the basis of the Schottky emission model.
The EL device with dithienosilole derivatives (DTS) as an electron injection layer has a
lower energy barrier (0.33 eV) for electron injection from magnesium compared to that
(0.43 eV) of a typical EL device without DTS. This may lead to the improvement in the
electrical properties of the EL device with DTS.
Optical Properties of Polymer-like Organic Thin Films Deposited by Plasma-Enhanced Chemical Vapor Deposition Using Toluene as the Precursor
Authors: Chun Quan Jongryang Joo , Jun Kim Donggeun Jung , Youl Kim Sang
Published: October 2002

Polymer-like organic thin films (POTFs) were deposited by plasma-enhanced chemical vapor deposition (PECVD) using toluene as the precursor. Refractive indices and
extinction coefficients of the POTFs could be varied by changing the plasma power and
the deposition temperature, which are easily and continuously controllable deposition
parameters.
Pattern Fabrication Technique for Ta–Ge Amorphous X-Ray Absorber on a SiC Membrane by Inductively Coupled Plasma
Authors: Iba Yoshihisa , Kumasaka Fumiaki , MasakiYamabe MasakiYamabe
Published: October 2002

We developed a pattern etching method for Ta–Ge (Ta3Ge)
amorphous X-ray absorbers on a SiC membrane using a mixture of
Cl2 and BCl3 gases with a single-layer e-beam resist. For
this work, an inductively coupled plasma (ICP) etcher with a helium
back surface cooling system was used. High etching selectivity and
anistropic etching were achieved by regulating electrode temperature
and BCl3 concentration ratio. The etching selectivity of
Ta3Ge to the resist is 6.5. Ta3Ge patterns of 0.1 µm
dimensions with vertical sidewalls were fabricated. Good etching rate
uniformity was also obtained over a 61-mm-diameter membrane field. We
found that Ru film was a suitable etching stopper material because it
has high dry-etching durability and can be easily removed by oxygen
plasma etching.
Dynamics of a Nonlinear Electromagnetic System
Authors: Chang Shun-Chang , Tung Pi-Cheng
Published: October 2002

An experiment with a test rig consisting of a symmetric rotor suspended by
a spring device and excited by a series of nonlinear electromagnetic forces has
been performed by Chang and Tung [Sound & Vib. 214 (1998) 853], to investigate the effects of an electromagnet processing highly nonlinear
characteristics on general mechanical systems. A nonlinear mathematical model
has been obtained by applying a modified conventional identification technique
based on the principle of harmonic balance. In this study, analytical work is
carried out on this identified nonlinear model by applying the first-harmonic
approximation solution and the Floquet theory. The resulting criteria for
bifurcations can be used to evaluate the operational range of a system
employing such a nonlinear actuator. We also employ the method of Lyapunov
exponents to show the occurrence of chaotic motion and to verify the above
analyses. A comparison of the analytical results with those of the experimemt
shows that the identified nonlinear model obtained from the experiment can
predict and characterize the dynamics of a real electromagnetic system.
Chemical Vapor Deposition of Ru and Its Application in (Ba,Sr)TiO3 Capacitors for Future Dynamic Random Access Memories
Authors: Aoyama Tomonori , Kiyotoshi Masahiro , Yamazaki Soichi , KazuhiroEguchi KazuhiroEguchi
Published: October 2002

Ru films were fabricated by chemical vapor deposition using Ru(C5H5)2 and O2.
The deposition of Ru film was controlled by the surface reaction kinetics as the rate limiting
step with activation energy of 2.48 eV below 250°C and by the mass transport process
above 250°C. Ru films had a polycrystalline structure and showed low resistivity of about
12 µΩcm. Ru films deposited at 230°C showed excellent step coverage. We applied Ru
films prepared by chemical vapor deposition to the bottom electrode of a Ba0.25Sr0.75TiO3
capacitor and obtained good electrical characteristics.
Plasma-Damage-Free Gate Process Using Chemical Mechanical Polishing for 0.1 µm MOSFETs
Authors: Saito Tomohiro , Yagishita Atsushi , Inumiya Seiji , Nakajima Kazuaki , Akasaka Yasushi , Ozawa Yoshio , Yano Hiroyuki , Suguro KatsuhikoHieda , Arikado Tsunetoshi , Okumura Katsuya
Published: October 2002

We propose a new transistor process called the Damascene
gate process, where in
a gate electrode is patterned by chemical mechanical polishing (CMP). In this process,
source/drain implants are carried out by using a dummy gate pattern as a mask and
activation annealing is completed before the actual gate oxide formation. After
removal of the dummy gate, fresh oxide and gate electrode films are formed in grooves
and the gate electrode film is patterned by CMP. As a result, the gate electrode surface
is completely planarized and the sheet resistivity of the gate electrode is very uniform in
a line width range from 0.2 µm to 5 µm. Metal-oxide-semiconductor-field-effect-transistors (MOSFETs) formed by the Damascene gate process were found to show
higher electron mobility, smaller threshold voltage deviation and lower subthreshold
swing due to lower surface state density as compared with conventional transistors.
Therefore, the Damascene gate process is promising for the fabrication of sub-quarter-micron MOSFETs.
Efficient Production of O- by Dissociative Attachment of Slow Electrons to Highly Excited Metastable Oxygen Molecules
Authors: Daiyu Hayashi Daiyu Hayashi , Kiyoshi Kadota Kiyoshi Kadota
Published: October 2002

In this paper, the mechanism for efficient production of O- in the afterglow of a low-pressure and high-density oxygen plasma has been described.
We proposed a new production process, the dissociative attachment of slow electrons to highly excited metastable oxygen molecules O2 (A3 Σu
+, A'3Δu, c1Σu
-).
The electron attachment frequency has been obtained from the experimental results, and was significantly high for the electron temperature of less than 2 eV. The cross section, σDA, for this process was evaluated by a quantum mechanical approach.
σDA at 0.1 eV was larger by two-orders of magnitude than the peak value at 6.7 eV for the ground state O2 (X3Σg
+).
The enhancement of the electron attachment frequency at low temperature can be explained by dissociative attachment of slow electrons to O2 (A3Σu
+, A'3Δu, c1Σu
-).
Analog MOS Circuits for Motion Detection Based on Correlation Neural Networks
Authors: Tetsuya Asai Tetsuya Asai , Masahiro Ohtani Masahiro Ohtani , Hiroo Yonezu Hiroo Yonezu
Published: October 2002

We propose simple analog MOS circuits producing one-dimensional optical flows aiming at the realization of compact motion-sensing circuits. In the proposed circuit, the optical flow is computed by a number of local motion sensors which are based on biological motion detectors. Mimicking the structure of biological motion detectors made the circuit structure quite simple, compared with conventional velocity sensing circuits. Extensive simulation results by a simulation program of integrated circuit emphasis (SPICE) indicated that the proposed circuits could compute local velocities of a moving light spot and showed direction selectivity for the moving spot, which implies that a high-resolution motion-sensing chip can be realized using standard analog very large-scale integration (VLSI) technology.
Stress-Induced Device Degradation Due to Die-Attachment Process after Area Bump Formation
Authors: Shimoyama Nobuhiro , Machida Katsuyuki , Shimaya Masakazu , Kyuragi Hakaru
Published: October 2002

This paper presents the effect of stress on device degradation in metal-oxide-semiconductor field-effect transistors (MOSFETs) due to the die-attachment
process after area bump formation. Device degradation increases with increasing stress
induced by die-attachment onto an area bump sample. The degradation results mainly
from interface trap generation at the Si-SiO2 interface and also from electron trapping
in the gate oxide. It is clarified that post-baking at 300°C eliminates the degradation.
However, the degradation due to the potting material appears again after post-baking.
Therefore, in order to decrease the amount of device degradation due to the packaging
process, both the post-baking condition and potting material need to be taken into
account when a packaging technology with area bump formation is used.
Gate Stack Architecture Analysis and Channel Engineering in Deep Sub-Micron MOSFETs
Authors: Inani Anand , Rao Ramgopal Valipe , Cheng Baohong , Woo Jason
Published: October 2002

Scaling of metal-oxide-semiconductor (MOS) transistors to
smaller dimensions has been a key driving force in the IC industry. As
we approach the sub-quarter micron regime, a whole new set of problems
regarding the device performance arises. One of the major concerns is
the high gate leakage current. To address this problem, a lot of
effort has been concentrated on the use of the so-called “high-K
dielectrics” as gate insulators. However, the implications of using
these materials on the electrical performance of MOS devices need to
be studied. This work is an effort towards the same. There has also
been a lot of discussion
about the trade-offs related to the use of
retrograde channel profiles in deep sub-micron transistors. It is
also shown in this work that a retrograde profile can
be optimized to have an advantage over uniform doping.
Device Physics of Ferroelectric Thin-Film Memories
Authors: Scott J. F.
Published: October 2002

Band structure match-ups are given theoretically from X-ray photoemission spectroscopy (XPS) for the electrode interfaces between
platinum electrodes and the ferroelectric thin-film materials
commonly used for random access memories (DRAMs and nonvolatile
FRAMs): strontium bismuth tantalate (SBT), barium strontium
titanate (BST), and lead zirconate titanate (PZT). The results all agree
with experimentally measured Schottky barrier heights. The electronegativity constant or S-factor (derivative of Schottky barrier height
with respect to electron affinity) is found to be approximately 0.7 for
these materials, not the purely ionic value of 1.0. The reduction of a
factor of a million in the effective Richardson coefficient is explained.
And the paradox of avalanche breakdown but decreasing breakdown
fields with increasing temperature is reconciled.
A Fatigue-Tolerant Metal-Ferroelectric-Oxide-Semiconductor Structure with Large Memory Window Using Sr-deficient and Bi-excess Sr0.7Bi2+yTa2O9 Ferroelectric Films Prepared on SiO2/Si at Low Temperature by Pulsed Laser Deposition
Authors: Noda Minoru , Matsumuro Yoshinori , Sugiyama Hideki , Okuyama Masanori
Published: October 2002

Preferentially (105)-oriented Sr0.7Bi2.8Ta2O9(SBTO) thin films on SiO2/n-Si(100) have
been prepared by a pulsed laser deposition method at temperatures as low as 350°C, which is
the lowest process temperature for growing SBTO ferroelectric thin films. Dielectric properties of SBTO films
have been improved by increasing the Sr/Bi atomic ratio from 0.7/2.8 to 0.7/2.0. A memory window as large
as 3.6 V in the Metal-Ferroelectric-Insulator-Semiconductor(MFIS) capacitor has been obtained at a Sr/Bi
ratio of 0.7/2.0. This is the largest value among the MF(I)S diode structures. Little degradations in C-V are
observed up to fatigue of over 1010 cycles for a process temperature of 400°C, or especially for Sr/Bi of
0.7/2.0, keeping the memory window at more than 3.2 V. It should be emphasized that improvement in memory
characteristics is strongly related to the insulating properties of the ferroelectric and dielectric thin films rather
than to the value of the dielectric constant.
Improvement of SiO2/4H-SiC Interface Using High-Temperature Hydrogen Annealing at Low Pressure and Vacuum Annealing
Authors: Fukuda Kenji , Nagai Kiyoko , Yoshida ToshihiroSekigawa , Arai Kazuo , Yoshikawa Masahito
Published: October 2002

The influences of high-temperature H2 annealing at low
pressure (8.5×102 Pa at 1273 K) and vacuum (1×
10-4 Pa at 1273 K) annealing on capacitance-voltage (C-V)
characteristics of 4H-SiC MOS structures have been
investigated. H2 annealing more effectively reduced the flat band
voltage shift of the 4H-SiC MOS structure than vacuum annealing. The
interface state density of the 4H-SiC MOS structure after H2
annealing at 1273 K was reduced to approximately one-fifth that of
the sample without H2 annealing. Secondary ion mass spectroscopy
(SIMS) revealed that hydrogen accumulated at the SiO2/4H-SiC
interface, and its density increased with H2 annealing temperature.
Multilevel Aluminum Dual-Damascene Interconnects for Process-Step Reduction in 0.18 µm ULSIs
Authors: Shiba Kazutoshi , Wakabayashi Hitoshi , Kikuta ToshiyukiTakewaki , Kubo Akira , Yamasaki Shinya , Hayashi Yoshihiro
Published: October 2002

Multilevel Al dual-damascene interconnects are fabricated with laminated SiO2/SiON films for the
reduction of the number of steps in the fabrication process. In the dual-damascene structure composed of the
SiO2 in the line area and the SiON in the via area, the SiON films act not only as the etch-stop layer for line-trench
formation but also as the absorbent layer in KrF lithography, thus reducing the number of steps in the fabrication
process by 17%. The Al dual-damascene interconnects have a small via resistance of 1–2 Ω/via at a 0.28 µm
diameter. The low resistance is retained in the stacked via structure. This process is especially applicable for
fabricating the lower level interconnects in low-cost, 0.18 µm complementary-metal-oxide-semiconductor ULSI.
Ultra-Low Resistance, Through-Wafer Via (TWV) Technology and Its Applications in Three Dimensional Structures on Silicon
Authors: Soh Hyongsok T. , Yue C. Patrick , McCarthy Anthony , Ryu Changsup , Lee Thomas H. , Wong S. Simon , Quate Calvin F.
Published: October 2002

This paper presents an ultra-low resistance, high wiring density, through-wafer
via (TWV) technology that is compatible with standard silicon wafer processing.
Vias as small as 30 µm by 30 µm are fabricated through a 525 µm thick wafer. This
results in an aspect ratio for the via that is greater than 17:1. Furthermore,
the dc resistance of a single via is less than 50 mΩ. Key fabrication steps,
including the silicon dry etch, copper metallization, and photoresist
electroplating, are described in detail. As a demonstration of the potential
applications of the TWV technology, a novel three dimensional inductor is
designed and fabricated. For a 0.9-nH inductor, a quality factor of 18.5 is
measured at 800 MHz.
Tight-binding Molecular Dynamics Simulation of Desorbed SiO Molecule during the Oxidation of Si(111) Surface
Authors: Yamada Aruba , Ammal Akira Endou , Kubo Momoji , Nakamura Kazutaka G. , Masahiro Kitajima Masahiro Kitajima , andAkira Miyamoto andAkira Miyamoto
Published: October 2002

Tight-binding molecular dynamics calculations have been carried out to study the SiO
desorption at high temperature during the oxidation of Si(111) surface. In our model, the
on-top site of SiO at the Si(111) surface was heated partially on purpose. The high
wagging and stretching energies related to the SiO are considered to be the origin of
SiO desorption for the present calculations. Vibrational frequencies at the oxygen
adsorption site on Si(111) surface and both rovibrational and translational energies of
desorbed SiO molecule were calculated and compared with the experimental results.
The SiO molecule desorbed at the thermal equilibrium state which is in agreement with the experimental results.
Lateral Composition Modulation Induced Optical Anisotropy in InP/GaInP Quantum Dot System
Authors: Hong-Wen Ren Hong-Wen Ren , Mitsuru Sugisaki Mitsuru Sugisaki , Shigeo Sugou Shigeo Sugou , Kenichi Nishi Kenichi Nishi , Akiko Gomyo Akiko Gomyo , Yasuaki Masumoto Yasuaki Masumoto
Published: October 2002

GaInP lattice matched to GaAs (001) and InP/GaInP self-assembled quantum dots were grown by gas-source molecular beam epitaxy. Transmission electron microscopy and photoluminescence reveal that the composition-modulated lateral superlattice along the [110] direction dominates over Cu–PtB type long-range ordering on determining the strong spectral polarization of GaInP along the [110] direction. InP dots embedded in GaInP with the lateral superlattice show the same polarization in the photoluminescence spectra, the degree of polarization of quantum dots increases with that of the surrounding GaInP matrix to as high as 40%. Although the shape elongation of InP dots along the [110] direction is also observed, lateral composition modulation in the GaInP matrix is considered to be the major origin for the strong optical anisotropy in the InP/GaInP quantum dot system.
Coulomb Blockade in Resistively Coupled Single-Electron Transistor: Dependence on Bias Conditions
Authors: Pashkin Yuri A. , Nakamura Yasunobu , Tsai Jaw-Shen
Published: October 2002

We have measured resistively coupled single electron transistors under two bias conditions: asymmetric
and symmetric. We observed a characteristic Coulomb blockade pattern whose shape is significantly
different for the two cases. Our simulations based on the orthodox theory of single-electron tunneling are in
good qualitative agreement with the experimental data.
Analysis of Buried-Oxide Dielectric Breakdown Mechanism in Low-Dose Separation by Implanted Oxygen (SIMOX) Substrates Fabricated by Internal Thermal Oxidation (ITOX) Process
Authors: Kawamura Keisuke , Hamaguchi TakayukiYano , Takayama Seiji , Nagatake Youichi , Matsumura Atsuki
Published: October 2002

Buried-oxide (BOX) dielectric breakdown behavior of low-dose
separation by implanted oxygen (SIMOX) substrates fabricated by the
internal thermal oxidation (ITOX) process was analyzed. From the
time-zero dielectric breakdown (TZDB) characterization of the
metal-oxide-semiconductor (MOS) capacitors using BOX as a
dielectric, of various areas, BOX breakdown was found to be
dominated by the electrically weak spots (EWS's) distributed
randomly in the BOX layer. The densities of EWS's show good
correlation with those of Si islands in the BOX for several samples,
indicating that the Si islands are the main cause of BOX
breakdown. A model for extracting the EWS density as a function of
breakdown field is proposed, the appropriateness of which is
verified by its application to the experimental results. Using the
proposed model, the dependence of Si island density and their
thickness distribution on oxygen ion dose and ITOX layer thickness
was investigated, indicating that both dose reduction and ITOX
enhancement can effectively reduce the Si island density. By
combining the dose reduction and ITOX enhancement, BOX breakdown
characteristics, almost comparable to that of the thermally grown
oxide were attained, even for a relatively large capacitor area of 7.85×10-3 cm2, revealing the high performance of ITOX-SIMOX technology.
Nitridation of GaAs (001) Surface Studied by Auger Electron Spectroscopy
Authors: Aksenov Igor , Nakada Yoshinobu , Okumura Hajime
Published: October 2002

Auger electron spectroscopy (AES) has been used to investigate the processes taking place
during the initial stages of nitridation of GaAs(001)-2×4 surface by active nitrogen species.
The results of analysis of the spectral positions of the Auger electron signals from Ga, As
and N, as well as their dependencies on the nitrogen exposure show that the processes taking
place during nitridation greatly differ depending on the nitridation temperature. At low
temperatures (≤200°C) nitridation is hindered by kinetic restrictions on the atomic migration,
leading to the island growth with the formation of the disordered GaAsN phase in the
subsurface region. At high temperatures (≥500°C) the process of nitridation takes place
simultaneously with the etching of the surface due to decomposition of the substrate,
resulting in the rough interface between the GaN and GaAs phases. However, for
intermediate nitridation temperatures (300°C–400°C) AES results indicate that one
monolayer of N atoms may be formed on the substrate during the initial stage of nitridation.
The post-nitridation annealing of the samples nitrided at the intermediate temperatures results
in the formation of a crystalline GaN layer, the line shape of the AES signals from which is
identical to that for a GaN reference sample.
Growth Temperature Dependence of Self-Formation Process of Quantum Dot Structures in GaP/InP Short-Period Superlattices Grown on GaAs (311)A Substrate
Authors: Noh Joo-Hyong , Asahi Hajime , Fudeta Mayuko , Watanabe Daisuke , Mori Jun , Gonda Shun-ichi
Published: October 2002

Growth temperature dependence of the self-formation process of
quantum dot (QD) structures in (GaP)1.5 (InP)1.88
short-period superlattices (SLs) grown on GaAs (311)A substrates is
studied by scanning tunneling microscopy (STM). SLs are grown by
gas-source molecular beam epitaxy (MBE) at 420–500°C. The
STM image of the sample grown at 460°C reveals completely
self-formed QD structures aligned along both [233] and [011]
directions due to the strain-induced lateral composition
modulation. On the other hand, both below (420°C) and above
(480°C, 500°C) this temperature the self-formation
process of QD structures is suppressed and only incomplete structures
elongated along the [011] direction are formed, probably due to the
suppressed or over-enhanced migration of group III atoms on the
surface, respectively. Scanning tunneling spectroscopy (STS)
measurements reveal that the amplitude of the lateral periodic
variation of the band-gap energy in the self-formed structures also
decreases both below and above the optimum growth
temperature.
Digital Etching of InP by Intermittent Injection of Phosphorous Precursors in Ultra-high Vacuum
Authors: Otsuka Nobuyuki , Nishizawa Jun-ichi , Oyama Yutaka , Kikuchi Hideyuki , Suto Ken
Published: October 2002

Intermittent injections of phosphorous precursors, i.e. tris-dimethylaminophosphorus
(TDMAP) and tertiarybutylphosphine (TBP), have been applied for the selective etching of InP
(001) substrates in order to study surface adsorption/decomposition mechanism of phosphorous
precursors on the InP surface in ultra-high vacuum. Digital etching, in which the etching depth is
controlled by the number of injection cycles of etching gases and the etch rate is independent of
the injection time and pressure of the etching gas in a self-limiting fashion, is achieved for both
precursors. The etch rate is well described by a modified Langmuir-type equation. The TBP
molecules stick seven times faster than the TDMAP molecules on the InP surface and both
precursors prevent the decomposition of InP resulting from the phosphorus loss during an
evacuation time of over 5 s. On S-doped substrate grown by a vapor pressure controlled
Czochralski method, the activation energy of the digital etching with TBP significantly decreases
to 7 kcal/mol. Therefore, excellent uniformity and controllability of the etch rate is expected. A
specular etched surface is achieved and well controlled digital etching is realized at an etching
temperature as low as 304°C.
Characterization of Potential Modulation in Novel Lateral Surface Superlattices Formed on GaAs Multiatomic Steps
Authors: Yamatani Kazuki , Akabori Masashi , Motohisa Junichi , Fukui Takashi
Published: October 2002

We investigated the potential modulation in a novel lateral surface superlattice
(LSSL) structure which was realized by utilizing multiatomic steps. The structure
was grown by metalorganic vapor-phase epitaxy (MOVPE) on vicinal GaAs
substrates to introduce periodic thickness modulation to the channel GaAs layer with
spontaneously formed multiatomic steps. Devices having split gates were fabricated
on the epitaxially grown LSSL structure. The potential modulation was investigated
by a potential sweeping technique, where different bias voltages were applied to the
split gates to change the minima of the potential across the multiatomic steps. We
observed plateaus and oscillations of conductance as a function of the gate voltage.
Systematic shifts of these positions were also observed when offset voltages between
the two gates were applied and changed. These features are assumed to originate
from the potential modulation induced by multiatomic steps.
Quantum Efficiency of InP/InGaAs Uni-Traveling-Carrier Photodiodes at 1.55–1.7 µm Measured Using Supercontinuum Generation in Optical Fiber
Authors: Shimizu Naofumi , Mori Kunihiko , Ishibashi Tadao , Yamabayashi Yoshiaki
Published: October 2002

The input wavelength dependence of the external quantum
efficiency for InP/InGaAs uni-traveling-carrier photodiodes
(UTC-PDs) was examined. A supercontinuum generated in the optical
fiber was used as the monochromatic optical source with the
wavelength ranging from 1.55 to 1.7 µm. The observed flatness
of the efficiency shows the applicability of UTC-PDs to wide
bandwidth transmission systems in which the bandwidths of the
optical fiber and amplifier are fully utilized. It was also found
that a UTC-PD with an acceptor doping density of 2.5×1018 cm-3 in the photo-absorption layer has a larger external quantum efficiency than a UTC-PD with a lower doping density at a wavelength around 1.7 µm. The mechanism of this enhancement is discussed based on the absorption coefficient and pulse responses measured at various input wavelengths.
Growth and Characterization of Nitrogen-Doped MgSe/ZnSeTe Superlattice Quasi-Quaternary on InP Substrates and Fabrication of Light Emitting Diodes
Authors: Shinozaki Wataru , Nomura Ichirou , Hattori HiroyukiShimbo , Sano Takashi , Che Song-Bek , Kikuchi Akihiko , Shimomura Kazuhiko , Kishino Katsumi
Published: October 2002

Superlattice quasi-quaternaries (SL-QQs), consisting of MgSe/ZnSeTe short-period
superlattices, were grown on InP substrates by molecular beam epitaxy with nitrogen p-doping. By changing the Mg composition (i.e., the layer thickness ratio of MgSe in the
superlattice) from 0 to 0.76, the photoluminescence peak energy at 15 K increased from 2.11
to 2.68 eV. The N-doping of MgSe/ZnSeTe SL-QQs was performed by two processes, that
is by the modulation-doping into ZnSeTe and by the all-doping. For the modulation-doping,
a hole concentration of over 1×1018 cm-3 was obtained for Mg composition of less than
0.14, with decreased monotonically with increasing Mg composition. The hole
concentration increased by changing the doping process from the modulation-doping to the
all-doping. For example, the hole concentration increased from
1×1015 to 3×1017 cm-3 for
Mg composition of 0.4. ZnCdSe/MgZnCdSe(Te) light emitting diodes (LEDs) were
fabricated using MgSe/ZnSeTe SL-QQs as p-cladding layers having yellow emissions
around 577 nm at 77 K.
Periodic Boundary Quantum Chemical Study on ZnO Ultra-Violet Laser Emitting Materials
Authors: Ammal Yasunori Oumi , Momoji Kubo Momoji Kubo , Kazuo Teraishi Kazuo Teraishi , Akira Miyamoto Akira Miyamoto , Masashi Kawasaki Masashi Kawasaki , Mamoru Yoshimoto Mamoru Yoshimoto , Hideomi Koinuma Hideomi Koinuma
Published: October 2002

Periodic density functional calculations have been carried out to study
the surface structure and polarity of ZnO and also for the band gap
modulation of ZnO by doping with various metals such as Be, Mg, Ca, Sr
and Co. Our calculations reveal that the relaxation energy for the
[0001] O surface is higher than that of the [0001] Zn
surface and hence the O-terminated surface can be easily
reconstructed. The charge distribution analysis shows that the Zn atoms
in the [0001] Zn surface are more metallic and hence this surface cannot
form a stable structure. The calculations for the band gap modulation of
ZnO suggest that Mg doping is effective for obtaining a wide band gap
with a stable structure.