bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Evaluation of Error Detection and Correcting Code for Optical Disk (Long Distance Code)
Authors: Tanaka Kunimaro , Fujita Koji , Sakamoto Tuyoshi , Nagashima Ken , Negishi Yoshinori , Kurihara Yutaka
Published: October 2002

The interleaved Reed Solomon code called long distance code (LDC)
is used for error correction and detection in the recording format of
optical disks to maintain the integrity of recorded data. Performance
evaluation of the code is necessary when the code is applied to another
recording channel such as higher recording density one. Hence a performance
evaluator for LDC was developed. The program evaluates various LDCs by
changing the input parameters of the format. The performance evaluator
consists of a burst error length evaluator and an EDAC performance
evaluator. An ISO/IEC 15041 (540 MB 90mm MO disk) disk was assessed with
this evaluator. The results show that the raw error rate of disks in the
market is low enough for data integrity when defect management is applied.
The Applications of a Liquid Crystal Panel for the 15 Gbyte Optical Disk Systems
Authors: Ohtaki Sakashi , Murao Noriaki , Ogasawara Masakazu , Iwasaki Masayuki
Published: October 2002

We have studied the next-generation digital versatile disk (DVD) using a blue
laser and investigated the application of a liquid crystal (LC) panel to the high-density disk. The LC panel can easily shift the optical path length of light beams
making it possible to cancel out wavefront aberrations. First, the authors applied
an LC panel to a tilt servo system. Compared with a mechanical tilt servo system,
the LC tilt servo is expected to be more compact and reliable. We also developed a
system for sensing the amount of disk tilt by comparing the signal levels of
crosstalk from adjacent tracks. Consequently a tilt servo without any extra
sensors was achieved. Another application of the LC panel is for the
compensation of spherical aberrations. It was confirmed, by simulations and
experiments, that the LC panel was practically useful for correcting disk
thickness error which has been determined to become more serious when a blue
laser was used.
Detection of Readout Signals on High-track Density MO-Disk Using an Optical Phase Shifter and Deep Land/groove Recording
Authors: Kai Shinichi , Fukumoto Atsushi , Aratani ShinMasuhara
Published: October 2002

We report the results of magneto-optical (MO) detection using an optical
phase shifter and a deep land/groove disk. We measured the recording
characteristics in the direction of incident linear polarization and found that
polarization perpendicular to the groove is best for a deep groove disk. Using
perpendicular polarization, with a 693 nm wavelength diode laser and a 0.55-NA
objective lens, sufficient readout and recording margins to guard against optical errors
were obtained by the experiments at an area density of 3.69 Gbit/in2, which was
obtained using a 0.35-µm bit length and a 0.5-µm track pitch.
High Numerical Aperture Optical Recording: Active Tilt Correction or Thin Cover Layer?
Authors: Martynov Yourii V. , Hendriks Benno H. W. , Zijp Ferry , Aarts Jan , Baartman Jan-Peter , Rosmalen Gerard van , Schleipen Jean J. H. B. , Houten Henk van
Published: October 2002

Playback of a 12 cm diameter replicated ROM disc with a 0.6 mm substrate thickness and a storage capacity of 10 GB
has been achieved using a light path with a dual-lens objective with
NA=0.85 and active tilt control. The disc tilt margin exceeds
±0.7 degree. Also backward compatibility with digital versatile
disc (DVD) has been demonstrated. Active tilt correction is not
required for read out of a disc with a 0.1 mm transparent cover layer. This technique has also been studied experimentally. The merits and disadvantages of the two approaches are discussed.
A Disaster-Tolerant Widely Distributed File System Using Optical Disk Libraries
Authors: Ueno Masahiro , Murata Setsuko , Iwatsu Shigetaro , Tanabe Takaya
Published: October 2002

We have developed a disaster-tolerant widely distributed data-backup file system that
uses optical disk libraries and either simple or advanced small computer system interface (SCSI)
extension equipment. The latter includes a redundant arrays of inexpensive disks (RAID)
function. To evaluate the basic performance of the developed system, we first used the simple
SCSI extension equipment to investigate the effect of the SCSI command-queuing function used
in the local SCSI target module and found that it increases the processing speed. We then
examined the effect of delay due to the wide distribution and found that read/write throughput
was not affected up to distances of 10 km. Next we compared the performance of the backup
system using both types of SCSI extension equipment with that without extension equipment.
We found that the write speed is about the same for both, but the read speed is slower with the
SCSI extension when the data size exceeds 100 kB. Using the advanced equipment to distribute
the data to multiple disks solved the problem of non matching read speeds to a certain extent. A
backup system using the advanced equipment was applied to a database system by using a
database benchmark test program.
Preparation of Self-Assembled Mercaptoalkanoic Acid Multilayers on GaAs (110) Surfaces
Authors: Akio Nagahara Hirotaka Ohno , Wataru Mizutani Wataru Mizutani , Junkou Takagi Junkou Takagi , Hiroshi Tokumoto Hiroshi Tokumoto
Published: October 2002

Mono- and double layer films have been formed by the self-assembly of
16-mercapto-hexadecanoic acid, (MHDA), HS(CH2)15COOH, via selective
ionic interaction. To understand the formation process in the nanometer length scale,
atomic force microscopy (AFM) studies have been conducted in combination with micro
X-ray photoelectron spectroscopy (µ-XPS), Auger electron spectroscopy (AES)
and micro-fourier transform infrared spectroscopy with the attenuated total
reflection method (µ-FTIR ATR). After the formation of a self-assembled
monolayer (SAM) was completed, the surface treated
with copper ions was immersed in a solution of MHDA. By this method,
an atomically
smooth double layer was successfully formed on cleaved GaAs (110) surfaces. The
formation speed of the second layer was faster than that of the SAM, indicating
stronger interaction of thiol functional groups with Cu2+ ions than with GaAs
surfaces.
Optical Disk Cluster Drive and Its Optical Filler Disk
Authors: Tanaka Kunimaro , Masumiya KyosukeYoshimoto , SatoshiShimizu SatoshiShimizu
Published: October 2002

Optical memory has the advantage of large capacity, media
removability and high reliability. However, when it is used in such
systems as a home server, video on demand or network server, the data
transfer rate is too low. Use of an optical cluster drive is one of
the promising methods of increasing the data transfer rate. The
technical issues of optical cluster drive are reliability,
synchronization and filling of the disk exchange masking time. High
reliability can be obtained by application of the error-correcting
code to recording data. The time delay caused by verification can be
circumvented by utilization of the error-correcting code. Operation of
the optical cluster drive is masked during disk exchange. An optical
filler disk can eliminate the masking while satisfying the numerous
requirements of an optical cluster drive.
Cation-Deficient Spinel Ferrites: Application for High-Density Write-Once Optical Recording
Authors: Bouet Laurence , Tailhades Philippe , Pasquet Isabelle , Bonningue Corine , Brun Stéphane Le , Rousset Abel
Published: October 2002

Thin films of defect spinel ferrites can be used as write-once read-many
media working with blue wavelengths. In fact, because these non-stoichiometric
ferrites are metastable, they can be transformed into corundum phases at moderate
temperatures by a laser spot. The transformed regions have different optical
indices from the starting ferrite film, making the readout process possible.
Recording density of about 5 bits/µm2 was demonstrated.
Exchange-Coupled Magnetic Bilayer Media for Thermomagnetic Writing and Flux Detection
Authors: Nemoto Hiroaki , Saga Hideki , Sukeda Hirofumi , Takahashi Masahiko
Published: October 2002

We have newly developed a perpendicular thermomagnetic recording coupled with
magnetic flux detection. Conventional magneto-optical thin films with TbFeCo
compensation compositions are advantageous for thermomagnetic writing, but insufficient
for magnetic flux detection due to low flux density at room temperature. We therefore
designed magnetically exchange-coupled bilayer media suitable for flux detection by
adding a magnetic layer with high flux density to a conventional TbFeCo magnetic
recording layer.
Conductance Oscillations in Low-Dimensional Ion Implanted Regions Annealed by Rapid Thermal Annealing
Authors: Kondo Hiroki , Kaga Kazutaka , Baba Shin-ichi , Iwano Hirotaka , Zaima Shigeaki , Yasuda Yukio
Published: October 2002

We have investigated the Coulomb blockade in gate-controlled hopping conduction systems
made up of small-dimensional focused ion beam (FIB) implanted wires having a small non-implanted gap. Dot structures are formed in the gap by potential fluctuations caused by dispersed
Ga impurities and implantation-induced defects. In the present work, the samples were subjected to
two thermal treatment methods: furnace annealing at 600°C for 30 min and rapid thermal annealing
(RTA) at 900°C for 30 s. In both samples, the conductance oscillates by varying the gate voltage at
low temperatures, in which the nearest-neighbor hopping conduction is dominant. In the samples
annealed by RTA, the oscillation amplitude becomes much larger compared with that of samples
annealed at 600°C, which suggests that implantation-induced defects are annihilated by the thermal
treatment at high temperatures. There coexist periodic and random peaks in the observed
oscillation, which originate from the Coulomb blockade and hopping path changes, respectively.
From obtained measurements, the dot size is estimated to be about 24 nm for the sample annealed
at 600°C and 14 nm for the sample annealed at 900°C. The width of tunneling barrier of the sample
annealed at 900°C was estimated to be about 14–17 nm.
Electrical Properties of Pulsed Laser Crystallized Silicon Films
Authors: Toshiyuki Sameshima Toshiyuki Sameshima , Keiko Saitoh Keiko Saitoh , Naho Aoyama Naho Aoyama , Seiichiro Higashi Seiichiro Higashi , Michio Kondo Michio Kondo , Akihisa Matsuda Akihisa Matsuda
Published: October 2002

Electrical properties of phosphorus-doped laser-crystallized silicon films were investigated. The analysis of free carrier optical absorption revealed that crystalline grains formed at laser energies of 360–375 mJ/cm2had high carrier mobilities of 40–50 cm2/Vs, which were close to that of doped single crystalline silicon. The mobility did not depend on the number of laser pulses. On the other hand, Hall effect measurements showed a marked increase in the carrier mobility of electrical current traversing grain boundaries from 3 to 28 cm2/Vs as the laser energy density increased from 160 to 375 mJ/cm2. The Hall mobility also increased as the number of laser pulses increased, although a single pulse irradiation resulted in a maximum carrier mobility of 15 cm2/Vs. These results suggest that a high laser energy density as well as numbers of multiple pulses are necessary to reduce disordered amorphous states and improve grain boundary properties.
New Method for Noncontact Atomic Force Microscopy Image Simulations
Authors: Naruo Sasaki Naruo Sasaki , Masaru Tsukada Masaru Tsukada
Published: October 2002

We developed a new method of numerical simulation for noncontact
atomic force microscopy (nc-AFM) images. This method works as a mapping
filter from the tip-surface interaction force into the nc-AFM
images. First we present a new method for image simulations. Next we
apply this method to the simulation of nc-AFM images of a Si(111)
7 ×7 reconstructed surface. Thus it is determined that our
method works well as an image simulator.
Effect of Group-Velocity Dispersion on Photon-Number Squeezing of Optical Pulses using Optical Fibers and Spectral Filter
Authors: Norihiko Nishizawa Norihiko Nishizawa , Takeo Horio Takeo Horio , Masakazu Mori Masakazu Mori , Toshio Goto Toshio Goto , Kazuo Yamane Kazuo Yamane
Published: October 2002

Photon-number squeezing of optical pulses using optical fibers
and band-pass spectral filters is numerically analyzed.
The evolution of the quantum noise in the optical pulse propagation is
calculated in both the spectral and time domains.
The mechanism of filtering squeezing and the role of the group-velocity
dispersion are investigated.
It is shown that the squeezing is realized owing to the interaction between the
self-phase modulation and the group-velocity dispersion.
Soft-X-Ray Lasers with Charge Transfer Pumping in a Mixture of Clusters and Atomic Gases
Authors: N. Chichkov Boris , Andre Egbert Andre Egbert , Susanne Meyer Susanne Meyer , Bernd Wellegehausen Bernd Wellegehausen , Lutz Aschke Lutz Aschke , Hans-Joachim Kunze Hans-Joachim Kunze , Yoshiaki Kato Yoshiaki Kato
Published: October 2002

Charge transfer in low-energy collisions of bare nuclei with atoms or partially stripped ions is a promising pumping mechanism for soft-x-ray lasers. For the demonstration of soft-X-ray lasers with charge transfer pumping, the use a mixture of clusters and atomic gases is suggested. When an intense femtosecond laser pulse is focused into such a medium, the clusters will be ionized to much higher ionization stages than the atoms. This allows creation of very favourable conditions for efficient charge transfer pumping.
Effects of Heat Treatment on Photorefractive Sensitivity of Ce- and Eu-Doped Strontium Barium Niobate
Authors: Tadayuki Imai Tadayuki Imai , Shogo Yagi Shogo Yagi , Hiroki Yamazaki Hiroki Yamazaki , Michio Ono Michio Ono
Published: October 2002

We investigated the effects of heat treatment on the data storage performance
of strontium barium niobate doped with cerium and europium. The
photorefractive writing sensitivity was increased by elevating the annealing
temperature. When the annealing was undertaken at a high temperature, for
example 900°C, the sensitivity reached a value about ten times
that obtained at an annealing temperature below 600°C. This increase
was caused by a photoconductivity increase which was probably due to an
increase in the oxygen vacancy concentration. The page multiplexing
performance of the crystal is also discussed in relation to the photorefractive
trap density.
A Pit-edge Detection Method for Tracking-error Signals Using a Monolithic Confocal Laser Coupler
Authors: Mizuno Takeshi , Narui Hironobu , OsamuMatsuda OsamuMatsuda
Published: October 2002

We propose a novel tracking-error signal detection method based
on the pit-edge detection method, using a monolithic confocal laser
coupler with a confocal knife edge structure (CKE device). The new
detection method, which we call the CKE pit-edge method, is applied to
an optical disk system in which the optical disk has a pit depth of
λ/4n. In this paper, we compare this new method to the
conventional pit-edge detection method using numerical analysis and a
simple model. Further, we also show that both the CKE pit-edge method
and our previously reported CKE push-pull method can utilize the same
CKE device.
A Monolithic Confocal Laser Coupler For an Optical Pick-up
Authors: Mizuno Takeshi , Doi Masato , Taniguchi YoshinobuHiguchi , Nakao NobukataOkano , Narui Hironobu , Matsuda Osamu
Published: October 2002

We propose a novel optical pick-up using a confocal laser
coupler for an optical disk player. The laser coupler consists of a
glass window and a monolithic optical element which includes a laser
diode, 8 photodiodes, and a pyramid-shaped prism mirror positioned
near the confocal plane which acts as a knife edge and a
photo-coupler. The focusing-error signal is detected using the
confocal knife edge (CKE) method and the tracking-error signal is
detected using the CKE push-pull method. The jitter of Compact Disc
(CD) readout was 6.7 ns at a line velocity of 1.2 m/s, and the DC
offsets of the tracking-error signal were sppressed to less than 1/3
for a radial lens displacement of ±400 µm compared to the
conventional push-pull method.
A Comment on Lightning Control Using a Femtosecond Laser
Authors: Chin See Leang , Miyazaki Kenzo
Published: October 2002

The current technique of lightning control using nanosecond CO2laser pulses and its limitations are analysed. The advantages of replacing the CO2laser pulses by intense femtosecond laser pulses without changing the basic design of the lightning control tower are analysed and discussed.
Light-Emitting Substituted Polyacetylenes
Authors: Sun Runguang , Zheng Qianbing , Zhang Xianmin , Masuda Toshio , Kobayashi Takayoshi
Published: October 2002

A series of polyacetylene derivatives such as
poly[(o-i-propylphenyl)acetylene] (PPA-iPr),
poly[1-(p-n-butylphenyl)-2-phenylacetylene] (PDPA-nBu), and
poly(1-hexyl-2-n-phenylacetylene) (PHPA) are systematically studied
and compared, with emphasis on the dependence of the luminescence
efficiency on the side groups and the optical and electronic
excitation processes in the polymers. Orange-red (600 nm), green
(530 nm), and blue (450 nm) photoluminescent (PL) and
electroluminescent (EL) emissions from these polymers are
observed. The corresponding PL quantum efficiencies are measured
using an integrating sphere and found to be lower than 0.1% for PPA-iPr, 49% for PDPA-nBu, and
62% for PHPA. The ionization energies are
5.3, 5.2, and 5.9 eV for PPA-iPr, PDPA-nBu, and PHPA,
respectively, measured by ultraviolet photoelectron spectroscopy
(UPS). It is shown that some of the substituted polyacetylenes can be
employed for lightemittingdiode (LED) fabrication, the quantum
efficiencies of which are comparable to those of other light-emitting
polymers.
Nonelectrical Poling in Ferroelectric Polycyanophenylenesulfides
Authors: Ide Junya , Tasaka Shigeru , Inagaki Norihiro
Published: October 2002

A new poling method utilizing the cooperativity of cyanophenyl groups
was proposed in ferroelectric polycyanophenylenesulfides (PCPS). The method
called “surface energy poling” takes advantage of the energy difference in
the top and bottom surfaces of a polar aggregate to form a remanent
polarization. The PCPS film sandwiched between a metal with higher surface
energy and polytetrafluoroethylene with lower surface energy was heated to
T
cp [1.2×T
g (glass transition temperature)] and cooled slowly to room
temperature. The remanent polarization that gives a pyroelectric constant of
10 µC/m2 K and an electrooptic coefficient (r
33) of 80 pm/V in the
resulting film was realized.
Changes in Hydrocarbon Chains and Head Groups in Distearoyl Phosphatidylcholine at 4th and 3rd Transitions under High Pressure
Authors: Utoh Shigenori
Published: October 2002

The highly ordered conformation of hydrocarbon chain packing
with orthorhombic symmetry in L-α-distearoyl phosphatidylcholine
under high pressure is confirmed using wide angle X-ray
diffraction and Raman scattering. With an increase in temperature
under high pressure, two phase transitions (the 4th and 3rd
counted from the well known main and pre-transitions) convert
the hydrocarbon chain packing from orthorhombic to quasi-hexagonal via, briefly, quasi-orthorhombic symmetry. This
behavior is closely related to the movement of the head group and
the occurrence of the gauche bond in the intrachain of
phospholipids. These phenomena occur after the phospholipid is
pressed above about 250 MPa and heated once above its melting
point.
Electron Emission Behaviors of Polycrystalline-Diamond-Coated Silicon Emitters
Authors: Yang Su-Hua , Yokoyama Meiso
Published: October 2002

In this work the electron emission characteristics of the polycrystalline-diamond-coated silicon field emission array (DSFEA) are examined, and its emission behavior is
compared with that of the bare Si field emission array (SFEA). For the DSFEA, a linear
ohmic and a Fowler-Nordheim (FN) emission are observed in the low- and high-applied-voltage regions, respectively. The threshold voltage for DSFEA is 235 V. The maximum
emission current of 0.23 mA is obtained at an applied voltage of 500 V. Using the FN plot,
the effective work function of DSFEA is calculated to be 0.2115 eV. The emission property of DSFEA in threshold voltage lowering is attributed to the structural defects in the diamond film, i.e., graphite inclusions, grain boundaries and surface protrusions of the diamond film.
Slow Secondary Electron Emission Yields at Near-Zero Kinetic Energy, Highly Charged Ion Impact
Authors: Hosaka Kazumoto , Tawara Hiro
Published: October 2002

An empirical formula has been proposed for the slow secondary emission yields from clean metals at near-zero velocity impact of ions with the potential energy up to a few 100 keV.
Field Emission Microscope Images of Oxygen Adsorption on Tungsten at 300 K and at Higher Coverages
Authors: Sato Mieko , Nishikawa Osamu
Published: October 2002

Adsorption of oxygen at higher coverages on a tungsten tip at 300 K is
characterized by the observation of field emission microscope images and using the
model proposed for field emission miceoscope (FEM) images of the gas-adsorbed hemispherical surface of body
centered cubic transition metals. The model is applied to the interpretation of the
dependence of sticking probabilities upon crystallographic planes shown in a recent
review and the scanning tunneling microscope images observed in oxygen adsorption
on (110) planes of face centered cubic metals.
Preparation and Characterization of Lead Zirconate Titanate Heterolayered Thin Films on Pt/Ti/SiO2/Si Substrate by Sol–Gel Method
Authors: Lee Sung-Gap , Shim Kwang-Taek , Lee Young-Hie
Published: October 2002

Ferroelectric Pb(Zr
x
Ti1-x
)O3 (PZT; x=0.2, 0.8) heterolayered thin films were fabricated by the spin-coating method on the Pt electrode alternately using PZT(20/80) and PZT(80/20) metal alkoxide solutions. All PZT heterolayered films show dense structure without the presence of the rosette structure. The lower PZT layers provide the nucleation site for the formation of a perovskite phase in the upper PZT films. Pb-deficient pyrochlore phase was formed at PZT/Pt interface due to diffusion of the Pb element into the Pt bottom electrode. The relative dielectric constant and dielectric loss of the six coated PZT heterolayered film were approximately 1385 and 3.3% at 1 kHz, respectively.
An Analytical Delay Model for Read Operation at Any Position on Dyamic Random Access Memory Bit Lines
Authors: Lin Hongchin , Sha Chia-Hsiang , Wong Shyh-Chyi
Published: October 2002

In deep submicron devices, the delay of interconnect becomes
comparable to that of gate, which limits the circuit
performance. Thus, it seems more appropriate to model the interconnect
and the gate as a single component in study the device
performance. Taking this approach, we develop an analytical model for
the signal for a pre-charged, deep submicron dynamic random access
memory (DRAM) at any position on the bit lines for read logic-1
operation. The bit line is modeled as a distributed
resistance-capacitance (RC) line and is simultaneously solved with the
drain current model. The model agrees well with the simulation program
integrated circuits emphasis (SPICE) simulations using Berkeley
short-channel IGFET model version 3 (BSIM3) models for various values
of the bit line resistance, the capacitance on both the bit line and
the sense amplifier, and the cell device width.
Effects of Impurity between Epitaxial Layer and Substrate on Current Transient for GaAs Metal-Semiconductor Field-Effect Transistors
Authors: Tanaka Shuichi , Ishii Hirotatsu
Published: October 2002

The effects of the impurity between the epitaxial layer and substrate (epi/sub) on the
current transient were examined by the drain bias pulsed current deep level transient spectroscopy
(DLTS) method. Test devices used for evaluation were GaAs metal-semiconductor field-effect
transistors (MESFETs) grown by metalorganic chemical vapor deposition (MOCVD). Energy-band diagram simulation of the MESFET structure showed that the drain bias pulsed current DLTS
method is suitable for determining the buffer layer quality. Negative DLTS spectra, which were
regarded to be caused by the electron emission in the AlGaAs buffer layer, were observed for both
the intentionally doped epi/sub sample and purified epi/sub sample. The intensity difference of these
DLTS signals could be explained by the quality change of the AlGaAs buffer layers. This electron
trap was determined to be the oxygen-related deep level. For the purified epi/sub sample, another
positive peak was found. The origin of this “hole trap”-like peak was discussed.
Electrical Properties of (Ba, Sr)TiO3 Films on Ru Bottom Electrodes Prepared by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition at Extremely Low Temperature and Rapid Thermal Annealing
Authors: Sone Shuji , Akahane Reiko , Arita Koji , Yabuta Hisato , Yamamichi Shintaro , Yoshida Masaji , Kato Yoshitake
Published: October 2002

(Ba, Sr)TiO3 (BST) films were prepared on Ru bottom electrodes by electron
cyclotron resonance chemical vapor deposition at extremely low temperature and rapid
thermal annealing (RTA). Leakage current characteristics were improved by lowering
the BST deposition temperature down to 120°C. (Ba+Sr)-rich films with a (Ba+Sr)/Ti
ratio of 1.1–1.5 had lower leakage current densities than stoichiometric and Ti-rich films
with a ratio of 0.8–0.9. Cross sectional transmission electron microscopy observations
showed that the 120°C-deposited and 700°C-RTA-treated (Ba+Sr)-rich film had a granular
structure and smooth interfaces with the electrodes. The stoichiometric and Ti-rich films
had columnar structures and larger interface roughness. As a result, low leakage current
density less than 10-7 A/cm2 at ±1 V were obtained for 30 nm-thick BST films with a
(Ba+Sr)/Ti ratio of 1.1–1.5 by combination of 120°C deposition and 700°C RTA.
Conformal Step Coverage of (Ba,Sr)TiO3 Films Prepared by Liquid Source CVD Using Ti(t-BuO)2(DPM)2
Authors: Kawahara Takaaki , Matsuno Shigeru , Yamamuka Mikio , Tarutani Masayoshi , Sato Takehiko , Horikawa Tsuyoshi , Uchikawa Fusaoki , Ono Kouichi
Published: October 2002

We study the application of (Ba,Sr)TiO3 (BST) films prepared by chemical
vapor deposition (CVD) method to ∼0.13-µm-scale devices, for
example, 4Gbit dynamic random access memories (DRAMs), whose minimum feature size and height of storage nodes are around 0.13
and 0.36 µm, respectively. It is necessary for these devices to obtain a conformal step
coverage of the BST films of more than 80% at an aspect ratio of 3–5, along with an
equivalent SiO2 thickness (t
eq) of 0.5 nm. Recently, a new Ti source, Ti(t-BuO)2(DPM)2 [bis (t-butoxy) bis (dipivaloylmethanato) titanium], whose Ti ion is
surrounded by four large organic ligands, was developed. It is more stable in THF
(tetrahydrofuran; C4H8O) solution and in the vapor phase than conventional Ti sources
such as TiO(DPM)2 [oxo bis (dipivaloylmethanato) titanium]. In fact, the step
coverages of the BST films using Ti(t-BuO)2(DPM)2 were found to be 80% and 70%
at aspect ratios of 3.3 and 5, respectively, which were much better than those of films
using TiO(DPM)2. Moreover, the electrical properties of the BST
films using Ti(t-BuO)2(DPM)2 were t
eq
=0.44 nm and a leakage current J
L of 2.8×
10-8 A/cm2 (+1.1 V) for a film of 24 nm thickness after post-annealing. These characteristics meet
the requirements of the 4Gbit DRAM capacitors.
Spatial Distribution and Characteristics of Ozone Generation with Glow Discharge using a Double Discharge Method
Authors: Hakiai Kazunori , Takazaki Daisaku , Ihara Satoshi , Satoh Saburoh , Yamabe Chobei
Published: October 2002

For the purpose of investigating the effect of a wide discharge gap (4 mm) on
ozone generation, a UV light absorption measurement technique has been used to
determine the spatial distribution of ozone concentration. A glow discharge at
atmospheric pressure was produced by a double discharge method with a pair of
metal-to-metal electrodes. Efficient and uniform ozone generation has been
accomplished. The obtained ozone concentration near the cathode is about 1.25 times
higher than that at the center of the main gap. The rate constant
κ1 for O+ O2+ M\stackrelκ1→ O3+ M yields the
values of (2.0–2.7)×10-34 cm6 molecule-2 s-1 from the ozone growth curve measured using the wavelength of 254 nm.
Endurance Characteristics and Degradation Mechanism of Polysilicon Thin Film Transistor EEPROMs with Electron Cyclotron Resonance N2O-Plasma Gate Oxide
Authors: Lee Nae-In , Lee Jin-Woo , Han andChul-Hi
Published: October 2002

Endurance characteristics and degradation mechanism of polysilicon thin film
transistor (poly-Si TFT) EEPROMs with electron cyclotron resonance (ECR) N2O-plasma oxide have been investigated. The ECR N2O-plasma oxide has Qbd up to
10 C/cm2 due to the smooth interface and strong Si-N bonds. The poly-Si TFT
EEPROMs have a larger threshold voltage shift of 2.5 V even after 105 program and
erase (P/E) cycles. The threshold voltage of the programmed device decreases until 104
P/E cycles, but after then increases, while that of the erased device increases after 103
P/E cycles. The degradation is ascribed to electron trapping in the oxide and the
generation of traps and interface states at the tunnel oxide/active poly-Si interface.
Soft Breakdown in Ultrathin SiO2 Layers: the Conduction Problem from a New Point of View
Authors: Miranda Enrique , Suñé Jordi , Rodríguez Rosana , Nafría Montserrat , Martín Ferran , Aymerich Xavier
Published: October 2002

In this work, the soft breakdown failure mode in ultrathin (<5 nm) SiO2 layers
is experimentally examined by means of current-voltage measurements
performed on samples with different gate areas, oxide thicknesses and
substrate types. The observed astounding matching which exhibits some of
these characteristics, as well as the common features with the final breakdown,
leads us to suggest that the current flow in the analysed regime might be
largely controlled by the extremely constrictive dimensions of the oxide
leakage spots. We present an alternative explanation to the soft breakdown
phenomenon which can be naturally extended to the final breakdown
conduction stage. In order to illustrate our ideas, a qualitative comparison with
the theoretical behaviour of a classical point contact system is also discussed.
Excimer-Laser-Induced In-Situ Fluorine Passivation Effects on Polycrystalline Silicon Thin Film Transistors
Authors: Kim Cheon-Hong , Jeon Jae-Hong , Yoo Juhn-Suk , Park Kee-Chan , Han Min-Koo
Published: October 2002

We report a new fluorine passivation method without ion implantation and additional annealing
step by low-temperature process and its effects on p-channel polycrystalline silicon (poly-Si) thin
film transistors (TFTs). The proposed method is not post-passivation, but in-situ passivation
because fluorine passivation is simultaneous with excimer-laser-induced crystallization by
employing excimer laser annealing of fluorine-doped silicon oxide (SiO
x
F
y
) on amorphous silicon
(a-Si) structure. From experimental results, it has been shown that in-situ fluorine passivation is
effective to improve the electrical characteristics, specially field-effect mobility, and the stability of
p-channel poly-Si TFTs. The improvement is due to fluorine passivation, which reduces the trap
state density and forms the strong Si-F bonds in place of the weak Si-H bonds in poly-Si channel
and SiO2/poly-Si interface.
Two-Dimensional Numerical Simulation of Solid-Phase-Crystallized Polysilicon Thin-Film Transistor Characteristics
Authors: Chou Tsung-Kuan A. , Kanicki Jerzy
Published: October 2002

A new two-dimensional (2-D) numerical simulation model for the
solid-phase-crystallized polysilicon (poly-Si) thin-film transistors
(TFTs) is presented in this paper. The proposed model is mainly
based on the defects located at the poly-Si/gate oxide and
poly-Si/buffer oxide interfaces and at the intergrain
boundaries. The simulation results have shown to be consistent with
the experimental TFT data. It has been demonstrated that the
interface/grain boundary trap states have different effects on the
conduction mechanisms of the poly-Si TFTs. The characteristics of
the poly-Si TFTs are discussed in detail.
Interaction of Porous Pt-SnO2 Gate Metal-Oxide-Semiconductor Field-Effect Transistor Device with CO
Authors: Kasama Kouichirou , Sato Daisuke , Fukuda Hisashi , Nomura Shigeru
Published: October 2002

Novel gas-sensing devices based on a porous Pt-SnO2 metal-oxide-semiconductor field-effect
transistor (MOSFET) for carbon monoxide (CO) gas sensing have been fabricated. The structure
integrates the catalytic properties of porous Pt, a thin catalytic layer, and the spillover effect onto
SnO2, a gas adsorptive oxide, with surface-sensitive MOSFETs. The operation characteristics of
the device for the detection of CO are presented as a function of CO gas concentration and
operating temperature. The threshold voltage decreased rapidly with time when the device was
exposed to CO gas. It was possible to detect 54 ppm of CO gas with a response time of less than
1 min at an operating temperature of 27°C. A model was proposed to explain the operation. The
proposed sensing mechanism of the device is supported well by
experimental data.
Quantitative Evaluation of Dopant Loss in 5–10 keV As Ion Implantation for Low-Resistive, Ultrashallow Source/Drain Formation
Authors: Koh Meishoku , Furumoto KazuhikoEgusa , Seo ToruShirakata , Yokoyama KentaroShibahara , MasatakaHirose MasatakaHirose
Published: October 2002

The effectiveness of low-energy 5–10 keV As ion implantation for
sub-0.1 µm metal-oxide-semiconductor field-effect-transistors
(MOSFETs) has been investigated. When implantation energy is lowered
to 5 keV at a dose of 1×1014 cm-2, the sheet resistance of the
diffused layer increases steeply. The origin of the sheet resistance
increase in 5–10 keV As ion implantation has been quantitatively
studied paying attention to dopant loss. We found that 43% of
implanted As remains in a 5 nm screen oxide when implantation energy
is lowered to 5 keV. Moreover 50–70% of As in Si is lost by dopant
pileup at the SiO2/Si interface during 850°C annealing. The pileup
problem becomes more severe with junction depth reduction. By
optimizing the implantation energy and the ion dose, both low sheet
resistance and ultrashallow junction depth have been simultaneously
achieved.
Formation of Very Thin Epitaxial Al2O3 Pre-layer with Very Smooth Surface on Si (111) Using a Protective Oxide Layer
Authors: Jung Young-Chul , Miura Hiroyuki , Ishida Makoto
Published: October 2002

We propose the formation of an Al2O3 pre-layer using a
protective Si-oxide layer and an Al layer. Deposition of a thin
layer of aluminum onto a Si surface covered with a thin Si-oxide
layer and annealing at 800°C led to the growth of
Al2O3 layers on Si (111). A very smooth and uniform
Al2O3 (111) pre-layer film was epitaxially grown on a Si
(111) substrate. The surface of the γ-Al2O3 film
grown on the Al2O3 pre-layer was very smooth with a Z
range of ∼3 nm. However, the surface grown without the
Al2O3 pre-layer had numerous convex structures concerning
with SiO
x
clusters with a Z range of
∼10 nm. Etching of the Si substrate by N2O gas could be
avoided in the initial growth stage by the Al2O3
pre-layer. It was confirmed that the Al2O3 pre-layer was
effective in improving the surface morphology of the very thin
γ-Al2O3 films.
Spatial Current Distribution Inside the Switch Region of a Plasma Opening Switch with Coaxial Configuration
Authors: Ihara Satoshi , Mori Satoshi , Satoh Saburoh , Yamabe Chobei
Published: October 2002

The spatial current distribution in the switch region of a plasma opening
switch (POS) with coaxial configuration was observed using pick-up coils. Three
pick-up coils were positioned along the axial direction of the conductor in the
switch region. From experimental results, it was found that the conduction starts
at generator side of the switch region, and current is transferred from the
generator side to the load side in the opening operation during conduction
operation. Also, it is possible that the spatial current distribution formed just after
or before the opening operation at the load end of the switch region strongly
affects the efficiency of energy transfer toward the load.
A New Wafer Scale Chip-on-Chip (W-COC) Packaging Technology Using Adhesive Injection Method
Authors: Kurino Hiroyuki , Lee Kang Wook , Sakuma Katsuyuki , Nakamura Tomonori , Koyanagi Mitsumasa
Published: October 2002

In order to realize low cost and high density packaging technology, we propose a new wafer scale chip-on-chip (W-COC) packaging technology using the adhesive injection method. In W-COC packaging technology, chip-on-chip modules more than two hundreds are simultaneously formed at the wafer level. In addition, we can significantly improve the chip performance, because small micro-bumps, more than one million, can be formed on a chip and consequently a number of vertical interconnections can be formed between the two bonded chips. Therefore, it is very easy to introduce the parallel processing function in a W-COC module. Using this technology, we propose a new multichip module (MCM) consisting of single or multiple memory chips directly attached to a logic chip. In this paper, we describe key technologies to realize this new multichip module. We fabricated the W-COC test module and investigated its electrical performance using a micro-bump chain.
Mechanism of Defect Formation during Low-Temperature Si Epitaxy on Clean Si Substrate
Authors: Mizushima Ichiro , Koike Mitsuo , Sato Tsutomu , Miyano Kiyotaka , Tsunashima Yoshitaka
Published: October 2002

Defects having a mound structure are formed during Si epitaxy on (001) Si
substrates by low-pressure chemical vapor deposition at a low temperature of 700°C
under the condition of high deposition pressure, even if the surface is atomically clean.
The structure of the mound was a quadrangular pyramid, in which high-density
{111} twins exist. The formation of such defects is due to the high pressure of SiH4
and H2. Epitaxial growth with high perfection is suppressed by the high pressure of
the H2 ambient, because hydrogen suppresses both the decomposition of SiH4 and the
migration of atoms on the surface. However, at the same time, a growth front that
can realize the high deposition rate is preferred under the condition of high SiH4
pressure. Crystalline structure with {111} twins is favorable for attaining the high
growth rate because terraces and steps are formed at the growth front. Thus
mounds are formed due to the higher deposition rate on the edge of {111} twins than
that on the (001) plane.
Behaviors of Electron Capture Cross Sections in the Intermediate Velocity Regime on Ion-Atom Collisions
Authors: Rei Okasaka Rei Okasaka , Kenji Mita Kenji Mita , Shin Asada Shin Asada , Kazuyoshi Naemura Kazuyoshi Naemura , Yoshiho Seo Yoshiho Seo
Published: October 2002

The behavior of electron capture cross sections in the intermediate velocity regime are classified into two types: one showing moderate monotonic change against collision velocity and the other showing noticeable change with a clear maximum in the intermediate velocity regime. In order to reproduce the two types of velocity dependencies for the collision system of low-ionization-stage ions and light atoms, we proposed a velocity matching model for an electron capture process in the intermediate velocity regime, taking the characteristics of the intermediate velocity collisions into consideration; i) collisions with a small impact parameter are effective. ii) Finite relaxation time necessary for electron capture reduces the cross section proportionally to 1/V, as collision velocityVincreases. The limitations of the application of this model are also discussed.
Merits and Demerits of Single Electron Effects in Ultrasmall Semiconductor Devices
Authors: Ohata Akiko , Toriumi Akira
Published: October 2002

Anomalous telegraphic noise with four-level current fluctuations due to two
interactive random telegraph signals (RTSs) in small-area metal-oxide-semiconductor
field-effect transistors (MOSFETs) is reported. From the noise pattern and discussions
on the charging energy of a trap, the existence of interactive traps is demonstrated.
Furthermore, the problem of a floating-dot-gate memory cell is discussed from the
viewpoint of the existence of interaction between traps, which implies that the threshold
voltage could be affected by the spatial distribution of dots in a multi-dot floating-gate
memory cell.
Analyses of the Radiation-Caused Characteristics Change in SOI MOSFETs Using Field Shield Isolation
Authors: Hirano Yuuichi , Maeda Shigenobu , Fernandez Warren , Iwamatsu Toshiaki , Yamaguchi Yasuo , Maegawa Shigeto , Nishimura Tadashi
Published: October 2002

Reliability against radiation is an important issue in silicon
on insulator metal oxide semiconductor field effect transistors (SOI
MOSFETs) used in satellites and
nuclear power plants and so forth which are severely exposed to
radiation. Radiation-caused characteristic change related to the
isolation-edge in an irradiated environment was analyzed on SOI
MOSFETs. Moreover short channel effects for an irradiated
environment were investigated by simulations. It was revealed that
the leakage current which was observed in local oxidation of silicon
(LOCOS) isolated SOI MOSFETs was successfully suppressed by using
field shield isolation. Simulated potential indicated that
the potential rise at the LOCOS edge can not be seen in the case of
field shield isolation edge which does not have physical
isolation. Also it was found that the threshold voltage shift caused
by radiation in short channel regime is severer than that in long
channel regime. In transistors with a channel length of 0.18 µm, a potential
rise of the body region by radiation-induced trapped holes can be
seen in comparison with that of 1.0 µm. As a result, we must
consider these effects for designing deep submicron devices used in
an irradiated environment.
Improvement of Dry Etching Resistance of Resists by Deep UVCure
Authors: Kishimura Shinji , Sakai YoshikaKimura , Tsujita Kouichirou , Matsui Yasuji
Published: October 2002

The improvement of dry etching resistance of photoresists by the deep UV cure has been
attempted. We have tried deep UV cure under N2 gas flow for KrF chemically amplified
resists and obtained the same level of etching rates as novolak resists. While the rates
increased under dry air. The resists after deep UV cure under both N2 and dry air were found
to be cross-linked. The increase of carbonyl in Fourier transform infrared (FT-IR) spectra
under dry air may suggest that oxygen atoms in the polymer structure reduce the etching
resistance. For ArF resists, the combination of the incorporation of acryl unit into
methacrylate polymer and deep UV cure under N2 was an effective method for improving the
dry etching resistance. Using the model ArF resist consisting of acryl polymer, we obtained
the same dry etching resistance as a KrF resist with inhibiting film shrinkage by optimizing the
parameters of the deep UV cure.
Excitonic Luminescence from Self-Organized Quantum Dots of CdTe Grown by Molecular Beam Epitaxy
Authors: Shinji Kuroda Shinji Kuroda , Yoshikazu Terai Yoshikazu Terai , Kôki Takita Kôki Takita , Tsuyoshi Okuno Tsuyoshi Okuno , Yasuaki Masumoto Yasuaki Masumoto
Published: October 2002

Self-organized quantum dots (QDs) of CdTe were successfully grown on a ZnTe (100) surface by molecular beam epitaxy. Atomic force microscopy measurements of the uncapped samples revealed the formation of CdTe QDs with typical dot diameters of 20 ±2 nm and heights of 2.7 ±0.3 nm when a 3.5 monolayer-thick CdTe was deposited. In the photoluminescence (PL) measurements of the capped QDs, an intensive excitonic luminescence was observed at 4.2 K, the intensity of which was higher than the CdTe/ZnTe single quantum wells (SQWs) by 2–4 orders of magnitude. The temperature dependence of the intensity showed thermal quenching with an activation energy of 110 meV, which was about twice as large as those of SQWs. The PL decay time in QDs exhibited a different temperature dependence from SQWs – a temperature-independent decay time below 20 K. These results are interpreted as features of zero-dimensional confinement of excitons in QDs.
Computational Studies on GaN Surface Polarity and InN/GaN Heterostructures by Density Functional Theory and Molecular Dynamics
Authors: Ammal Takayuki Onozu , Momoji Kubo Momoji Kubo , Kazuo Teraishi Kazuo Teraishi , Akira Miyamoto Akira Miyamoto , Yasushi Iyechika Yasushi Iyechika , Takayoshi Maeda Takayoshi Maeda
Published: October 2002

We have performed periodic density functional calculations and molecular
dynamics (MD) simulations to investigate the reconstructions of the GaN
(0001) surface and the heteroepitaxial growth process of InN thin films
on the GaN surface. Grown GaN planes have a polar configuration. Surface
energy calculations predict that the reconstruction of the N-terminated
GaN (0001) surface is energetically more favorable than that of the
Ga-terminated surface. MD results suggest that the growth of InN thin
films on Ga- and N-terminated surfaces is different. On the N-terminated
surface, the surface morphology of the grown InN layer is
three-dimensional and rough. On the other hand, on the Ga-terminated
surface, it is observed that the InN molecules have adequate migration
mobility for growth and this suggests that the growth follows the
two-dimensional growth mode.
Quantum Dot Infrared Photodetector Using Modulation Doped InAs Self-Assembled Quantum Dots
Authors: Horiguchi Naoto , Futatsugi Toshiro , Nakata Yoshiaki , Yokoyama Naoki , Mankad Tanaya , Petroff Pierre M.
Published: October 2002

We report the quantum dot infrared photodetector using the modulation doped
InAs self-assembled
quantum dots. By modulation doping, it is possible to remove the effect of
the dopants on the energy
level in InAs dots and to attribute clearly the infrared photocurrent to the carrier excitation in InAs
dots. The infrared photocurrent in the detector was clearly observed up to
30 K. The peak energy
and the polarization dependence of the infrared photocurrent are comparable
to the infrared electron
excitation from the ground state in InAs dots to the conduction band edge of
GaAs barriers.
Structural Analysis of SiGe and SiGeC Alloys by Ab Initio Total-Energy Calculations
Authors: andMakoto Konagai Akira Yamada
Published: October 2002

The structural properties of SiGe and SiGeC alloys
are studied by
ab initio total-energy calculations.
It is found from these calculations that the Ge cluster is
a stable structure in a SiGe alloy. Furthermore, it is also
demonstrated that Vegard's law is valid
in a SiGeC system whose C content is less than 3%.
The total-energy calculation of the Si0.72Ge0.25C0.03
alloy in which the number of Ge–C bonds around a C atom varies
shows that the energy increases on increasing the number of Ge–C bonds.
The mechanism of this increase is considered, taking into account the
cohesive energy difference of the SiC and GeC alloys and the atomic
configuration around the C atom.
A Novel Linearization Method of Multiple Quantum Well (MQW) Electroabsorption Analog Modulator
Authors: Shin Myunghun , Hong Songcheol
Published: October 2002

A linearization method for a multiple quantum well (MQW) electroabsorption analog modulator is studied. We analyze the nonlinear characteristics of the light-voltage (L-V) transfer curve in a MQW electroabsorption modulator and estimate its intermodulation distortion (IMD). We propose a novel linearization method, the integration of twin MQW modulators with optical 3 dB couplers. This method can reduce IMD2 and IMD3 simultaneously by only adjusting the modulation depth and the bias voltage of each modulator. Results of simulations show that the method can suppress IMD2 and IMD3 to below -65 dBc at a modulation depth of 10% without any serious loss of optical signal power or increase in chirp.