bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Emission from Lead-Zirconate-Titanate Ferroelectric Ceramic Induced by Pulse Electric Field
Authors: Okuyama Masanori , Jun-ichi Asano Jun-ichi Asano , Yoshihiro Hamakawa Yoshihiro Hamakawa
Published: October 2002

Electron emission into vacuum from a thin plate of lead-zirconate-titanate (PZT) ferroelectric ceramics has been observed under the impression of pulse electric field. Electrons are emitted not only from the ceramic surface near the electrode edge but also through the thin metal electrode. The emitted charge per one pulse little depends on pulse frequency when it is less than 2 kHz, and so the current density can be enhanced by increasing the frequency. The emission is observed even at temperatures above Curie temperature. It is considered that the emission is induced by abrupt change of dielectric flux as well as the polarization reversal.
Effects of Pore Structure on Depolarizing Factor and Dielectric Constant of Porous Ceramics
Authors: Hisao Banno Hisao Banno
Published: October 2002

A depolarizing factor for porous ceramics was investigated. The dielectric constant and depolarizing factor were derived as functions of porosity based on some pore models such as ellipsoidal, modified cube (or 3-0) and 3-3 models together with a new modified 3-3 model proposed here. The results were compared with experimental data on porous ceramics of PTZ (Pb(Zr, Ti)O3) and TiO2. The depolarizing factor depends on inverse dielectric constant of the constituent substance, and is not always proportional to porosity p, in contrast to the prediction based on the ellipsoidal model. In addition, the depolarizing factor is highly dependent on pore structure of ceramics and can only be predicted by the modified cube model and the modified 3-3 model under the assumption of appropriate pore shape factors.
Behavior of Morphotropic Phase Boundary in Low-Temperature Sintered Lead Zirconate-Titanate Ceramics with BiFeO3and Ba(Cu0.5W0.5)O3
Authors: Dong Dunzhuo , Murakami Kenji , Okada Nagaya , Kaneko Shoji
Published: October 2002

The influence of the perovskite-type complex oxide additives, BiFeO3and Ba(Cu0.5W0.5)O3, on the morphotropic phase boundary (MPB) has been investigated in low-temperature sintered Pb(Zr, Ti)O3ceramics. The coexistence region of two tetragonal and rhombohedral phases of the Pb(Zr, Ti)O3ceramics on the MPB has been narrowed and shifted to the Ti-rich region of the composition by the above additives. The dielectric and piezoelectric properties of the Pb(Zr, Ti)O3were affected by this shift of the MPB and here the optimum Zr/Ti ratio of 52/48 was determined.
Growth of Crack-Free 3-Inch-Diameter Lithium Tetraborate Single Crystals by Czochralski Method
Authors: Komatsu Ryuichi , Uda Tadashi Sugihara
Published: October 2002

The growth of crack-free 3-inch-diameter lithium tetraborate ( Li2B4O7) single crystals by the Czochralski method has been studied. The relationships between crystal cracking rate during growth and the crystal rotation rate and the position of the work-coil have been examined. It is concluded that crystal cracking at a later stage of growth is related to the temperature fluctuation in melt.
Analytical Modeling of Short-Channel Behavior of Accumulation-Mode Transistors on Silicon-on-Insulator Substrate
Authors: Joachim Hans-Oliver , Yamaguchi Yasuo , Inoue Yasuo , Tadashi Nishimura Tadashi Nishimura , Natsuro Tsubouchi Natsuro Tsubouchi
Published: October 2002

In this paper we present a theoretical analysis of accumulation-mode (AM) silicon-on-insulator metal-oxide-semiconductor field-effect transistors (SOI MOSFET's) with gate lengths in the deep submicron region down to 0.1 µm. A two-dimensional analytical model has been developed which describes the short-channel behavior of the threshold voltage and subthreshold slope. The results are supported by numerical device simulation. It is found that the key factor for controlling short-channel effects in the AM SOI MOSFET is the reduction of thickness of the SOI layer. With 50 nm SOI film, the threshold voltage roll-off can be suppressed down to 0.25 µm gate length. The subthreshold slope factor degradation below 0.2 µm gate length is difficult to suppress since there is almost no influence of channel doping variation. Compared to the inversion-mode (IM) transistor, the AM SOI MOSFET has an inherently higher sensitivity to device parameter variations.
Half-Unit Cell Growth of Bi–Sr–Ca–Cu–O Thin Films
Authors: Kubota Nobuhiko , Yuh Shiohara Yuh Shiohara , Shoji Tanaka Shoji Tanaka
Published: October 2002

The growth units of superconducting Bi–Sr–Ca–Cu–O thin films were examined.
The films were prepared on Y3Al5O12 (YAG) single-crystal substrates by
metalorganic chemical vapor deposition (MOCVD). The growth process of the films at the
initial stage was investigated by cross-sectional high-resolution transmission electron
microscopy (HREM) and atomic force microscopy (AFM). We found evidence of half-unit cell
growth, and the top layer of the half-unit was determined to be a Bi–O layer by
angular-resolved measurement using X-ray photoelectron spectroscopy (XPS).
DC Superconducting Quantum Interference Device Magnetometer for Cryogenic Current Comparator
Authors: Masakazu Nakanishi Masakazu Nakanishi
Published: October 2002

A conventional dc superconducting quantum interference device (dc-SQUID) magnetometer
was developed to improve current resolution of a cryogenic current comparator (CCC).
Its resolution of magnetic flux in the frequency range from 1/100 to 1 Hz was 6.8×10-20 Wb
and was six orders of magnitude better that of a rf-SQUID magnetometer usually used for a CCC.
Molecular Orientation and Switching Behavior in Antiferroelectric Liquid Crystals Studied by Polarized Raman Scattering
Authors: Kim Kyeong Hyeon , Miyachi Kouichi , Ishikawa Ken , Hideo Takezoe Hideo Takezoe , Atsuo Fukuda Atsuo Fukuda
Published: October 2002

The orientational distribution in SmA, the switching behavior in SmC*,
and the molecular orientation of SmC
A

* have been investigated by means of
polarized Raman scattering due to the C–C stretching of phenyl rings in two antiferroelectric
liquid crystals. The scattered intensities, I

Z
Z
(ω) and I

Y
Z
(ω),
have been measured between crossed and parallel polars as a function of rotation angle,
ω, of homogeneously aligned cells about their surface normal. The order parameters,
<P
2> and <P
4>, and then the orientational distribution
function in SmA were obtained by utilizing the method of information entropy. The
electric-field-induced reorientation was observed in the rotation angle dependence:
I

Z
Z
(ω)∝cos
4(ω±Θ), where Θ is the tilt angle of
SmC*. The characteristic rotation angle dependence obtained in SmC
A

*
was described as I

Z
(ω)∝{cos
4(ω+Θ)+cos
4(ω-Θ)}/2.
This result supports the molecular orientation of SmC
A

* so far proposed
that the molecules in adjacent layers tilt in the opposite senses.
Preparation of (Ba, Sr)TiO3 Thin Films by Chemical Vapor Deposition Using Liquid Sources
Authors: Kawahara Takaaki , Yamamuka Mikio , Makita Tetsuro , Tsutahara Koichiro , Yuuki Akimasa , Kouichi Ono Kouichi Ono , Yasuji Matsui Yasuji Matsui
Published: October 2002

Thin films of (Ba, Sr)TiO3 with high dielectric constant were prepared on
Pt/SiO2/Si substrates of 6-inch-diameter by chemical vapor deposition using
liquid sources. Ba(DPM)2 and Sr(DPM)2 dissolved into tetrahydrofuran
were vaporized in a vaporizer at 523 K, and Ti(O-i-C3H7)4
was bubbled at 313 K. The mixture of the source vapors with O2 and N2O
was supplied to the reactor (10 Torr) at uniform velocities through a shower-type nozzle,
which realized uniform profiles in the deposited film thickness and composition.
The electrical properties are significantly influenced by the film composition, and
the typical properties obtained for a 800-Å-thick film prepared at the substrate
temperature of 823 K are an equivalent SiO2 thickness t
eq of 5.2 Å,
a leakage current J
L of 2.4× 10-6 A/cm2 (at 1.65 V), and a dielectric loss tan
δ of 0.07.
Growth of Crystalline SrTiO3 Films on Si Substrates Using Thin Fluoride Buffer Layers and Their Electrical Properties
Authors: Bum Ki Moon Bum Ki Moon , Hiroshi Ishiwara Hiroshi Ishiwara
Published: October 2002

Strontium titanate ( SrTiO3: STO) films were grown epitaxially on Si (111)
and (100) substrates using thin SrF2 buffer layers. The SrF2 buffer
layer was used for preventing the formation of an amorphous SiO2 layer on the
Si substrate during deposition of an STO film. It was found from X-ray diffraction (XRD)
analysis that well (110)-oriented STO films were grown on Si(111) substrates by a
two-step growth method, in which a thin (8 nm thick) STO film was predeposited on the
SrF2 buffer layer at 450°C and a thick (80 nm thick) STO film was
successively deposited at 750°C. It was also found from XRD and Auger
electron spectroscopy (AES) measurements that the SrF2 buffer layer was
completely dissolved during STO film deposition at 750°C, and no fluorine
(F) atoms existed in the buffer layer. The epitaxial relationship on Si(111) substrates
revealed by X-ray pole figure measurements was (110)
S
T
O
//(111)
S
i

and <110>
S
T
O
//<112>
S
i
, while that on Si(100) substrates was
(100)
S
T
O
//(100)
S
i
and <110>
S
T
O
//<110>
S
i
or
<110>
S
T
O
//<100>
S
i
. Concerning the electrical
properties of STO films, the best values of breakdown field (at 1 µ A/cm2), resistivity
(at 1 MV/cm), and relative dielectric constant were 2.3 MV/cm, 8.2×1012 Ω· cm and 72, respectively.
Drift Velocity of Electrons in Helium-Based Gas Mixtures Measured with a UV Laser
Authors: Nitoh Osamu , Takahashi Kaoru , Shinohara Takuo , Uno Osamu Tsumura
Published: October 2002

For the central tracking chamber at the KEK B-factory, the use of a low Z gas in
the drift chamber is preferred. We have measured the drift velocity of electrons in
helium-based gas mixtures using a pulsed UV laser beam. In this paper, we describe the
results of our precision measurement of drift velocities using various mixtures of
helium and ethane. In addition, the effect of water vapor contamination on the drift velocities is also studied.
Electron Temperature in RF Discharge Plasma of CF4/N2 Mixture
Authors: Kobayashi Hidehiko , Itsuo Ishikawa Itsuo Ishikawa , Shinji Suganomata Shinji Suganomata
Published: October 2002

In 1 MHz discharges of CF4/N2 mixtures at a total pressure of 0.5 Torr,
the synergistic variation of the electron temperature was observed with various gas
mixing ratios. This variation at CF4 ratio of around 95% is ascribed to the
enhancement of electronegativity, and another at CF4 ratio of around 20% is due
to the expansion of the discharge region outward from the space between electrodes.
Rotational Properties of a Motor with Resonating Crystalline Quartz
Authors: Takashi Aoki Takashi Aoki , Toshiharu Suzuki Toshiharu Suzuki
Published: October 2002

Mechanical rotations of X-Y-Z-cut crystal resonators (rectangular parallelepipeds
cut perpendicular to the X, Y and Z axes) were investigated as functions of
electrode gaps, ring-spacer dimensions, and acoustic streamings. The crystals of certain
dimensions rotated when resonating at fundamental frequencies f

X 1 of the
X axis thickness vibrations and at satellite frequencies near f

X 1,
with use of a particular ring spacer under the crystal. Under the experimental conditions
used by us, it was found that the horizontal components of the acoustic streamings
(wind) play no important role in the rotation, and that there are some cases where
the rotational directions change depending on the frequencies.
The Influence of Oxidation Temperature and Gate Metal on the Electrical Properties of InP Metal-Insulator-Semiconductor Tunnel Diodes
Authors: Ghader Eftekhari Ghader Eftekhari
Published: October 2002

The electrical properties of InP metal-insulator-semiconductor (MIS) diodes with a thermally grown oxide interfacial layer were investigated. The oxidation temperatures were 400° C, 450° C and 500° C, and gate metals were Al, Au, Cu, and Pt. Diodes with interfacial layers grown at 450° C showed better characteristics. The parameters under investigation were barrier height, ideality factor and interface state density. Diodes with interfacial layers grown at 500° C had poor characteristics. In diodes with interfacial layers grown at 400° C and 450° C the barrier height varied linearly with the metal work function. The pileup of phosphorus atoms at the oxide-InP interface and presence of an indium-rich oxide layer next to the metal at higher oxidation temperature and metal-oxide reaction were used to explain the observations.
Anisotropic Thermal Diffusivity and Conductivity of YBCO(123) and YBCO(211) Mixed Crystals. II
Authors: Ikebe Manabu , Fujishiro Hiroyuki , Naito Tomoyuki , Michiaki Matsukawa Michiaki Matsukawa , Koshichi Noto Koshichi Noto
Published: October 2002

The electron and phonon contributions to the thermal conductivity and diffusivity of the
YBa2Cu3O7-
x

(YBCO(123)) matrix phase in the mixed crystal were separated by use of the Kadanoff
theory. The phonon mean free path l
ph and the phonon relaxation time τ ph were determined. The phonon thermal conductivity and
diffusivity were analyzed based on the Tewordt and Wölkhausen theory to estimate the electron-phonon coupling
parameter λ and the strength of the various phonon scattering mechanisms.
Properties of Fe(001) Single-Crystal Films Grown by Sputter Beam Method
Authors: Okamoto Satoshi , Osamu Kitakami Osamu Kitakami , Yutaka Shimada Yutaka Shimada
Published: October 2002

Fe(001) single-crystal films were grown on GaAs(001) substrates by the sputter beam (SB) method. Under the
optimum etching condition of GaAs substrates, roughness of the film surfaces observed by atomic force microscope
(AFM) can be reduced appreciably, and very flat surfaces can be obtained. Auger electron spectroscopy (AES) gave
little evidence of interfacial diffusion between the film and the substrate. X-ray diffraction patterns of the films
indicate well-oriented crystal structures, that is, the half-width values of the rocking curve of the Fe(002)
reflection are nearly equal to that of the (004) reflection from the GaAs substrates. Furthermore, enhanced growth
of single-crystal films was also confirmed by the fact that the linewidth of ferromagnetic resonance (FMR) spectra
is equal to that of the single-crystal films formed by molecular beam epitaxy (MBE). These results indicate that
the SB method has some advantages as a method of single-crystal film synthesis.
Design and Lasing Operation of Micro-Arc-Ring Lasers
Authors: Mitsugi Satoshi , Kato Junichi , Koyama Fumio , Matsutani Akihiro , Toshikazu Mukaihara Toshikazu Mukaihara , Kenichi Iga Kenichi Iga
Published: October 2002

A micro-arc-ring cavity (MARC) laser is proposed for microphotonic integrated circuits. This device is based
on tightly confined optical waves by a total internal reflection in a lateral microcavity. We present a basic design
concept of a MARC laser for low-threshold operation and for transverse mode control. We have fabricated a
0.98 µ m GaInAs/GaAs strained quantum well MARC laser by using direct electron beam lithography and
reactive ion beam etching. The reflectivity of the etched reflector was estimated to be ∼ 74% from the
threshold.
Optical Anisotropic Behavior in Cyanine Dye J-Aggregate Langmuir-Blodgett Films
Authors: Saito Kazuhiro , Honda Shosaku , Mitsuhiro Watanabe Mitsuhiro Watanabe , Hiroshi Yokoyama Hiroshi Yokoyama
Published: October 2002

Pseudoisocyanine (PIC) J-aggregate Langmuir-Blodgett (LB) films were fabricated and their in-plane anisotropy
was examined based on the polarization dependence of optical spectra. The PIC J-aggregate LB films show a large
in-plane anisotropy in the J absorption band with the transition moment preferentially oriented perpendicular to the
dipping direction of the substrate. Change in spectral shape depending on the polarization direction, which suggests
Davydov splitting, was not observed. Interaction between surface plasmons on Ag thin film and the excitons in J
aggregates also shows in-plane anisotropy similar to the behavior in absorption spectra.
Numerical Analysis of Tunneling Current due to Electric Field Concentration at Gate Edge of Polysilicon/SiO2/Silicon Structures
Authors: Muto Hirotaka , Kitabayashi Hiroyoshi , Nakanishi Koichiro , Wake Setsuo , Nakajima Moriyoshi
Published: October 2002

Tunneling current enhancement due to electric field concentration at a gate edge is investigated by numerical calculation. The detailed current distribution and change of current-voltage ( I-V) characteristics are calculated for several gate geometries differing in curvature radius. It is shown that the current density of an MOS structure with an oxide thickness of 12 nm varies by 3 orders of magnitude when the curvature radius at the gate edge changes from 30 nm to 2 nm. A very narrow region of 8 nm at the curvature area is responsible for 80% of the total current between the gate and n+ region. The calculated change in I-V characteristics is consistent with the experimentally measured I-V curve of a polysilicon gate/SiO2/n+-silicon structure.
Molecular Orientation of Polyimide Films for Liquid Crystal Alignment Studied by Infrared Dichroism
Authors: Sawa Kyoko , Sumiyoshi Ken , Hirai Yoshihiko , Kazuo Tateishi Kazuo Tateishi , Taibun Kamejima Taibun Kamejima
Published: October 2002

An orientation structure of polyimide film, which is introduced by rubbing in liquid crystal device (LCD)
fabrication, is clarified by polarized infrared spectroscopy. Samples rotated in-plane around the polarized incident
beam reveal that the orientation direction of the rubbed polymer chain coincides with the rubbing direction. A
sample-tilt measurement, in which the sample is tilted around the vertical axis, reveals that the polymer chains
are tilted at an angle to the substrate surface. A simple model is proposed in order to estimate the thickness of
the oriented layer of the rubbed film. In the model, the degree of dichroism of parallel and perpendicular polarized
IR spectra is calculated as a function of polymer film thickness. Comparing the model with experimental data, it is
determined that the thickness of the oriented layer is less than 14 nm.
ESR of Photodarkened CdS-Doped and Undoped Glasses
Authors: Miyoshi Tadaki , Ken-ichi Towata Ken-ichi Towata , Naoto Matsuo Naoto Matsuo
Published: October 2002

Electron spin resonance (ESR) and luminescence were measured in CdS-doped glass and undoped glass, which does
not contain CdS microcrystals. Photoinduced centers responsible for the photodarkening effects were detected by ESR
in the CdS-doped glass. This ESR signal is different from that of the host glass. This result indicates that the
centers responsible for the photodarkening are not associated with the centers in the glass.
Fabrication of Self-Aligned Aluminum Gate Polysilicon Thin-Film Transistors Using Low-Temperature Crystallization Process
Authors: Ohno Eizo , Yoshinouchi Atsushi , Hosoda Takeshi , Itoh Masataka , Tatsuo Morita Tatsuo Morita , Shuhei Tsuchimoto Shuhei Tsuchimoto
Published: October 2002

The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400° C to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600° C activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 µm.
Novel Amorphous-Crystalline Silicon Heterojunction Switching Devices with Bidirectional Switching Characteristics
Authors: Chen Kuin-Hui , Fang Yean-Kuen , Liu Ching-Ru , Kuo Bou-Chen Fang
Published: October 2002

An amorphous-crystalline silicon heterojunction switching device with the structure of
a-Si( n+-i-p)/c-Si(n)/a-Si(p) has been
developed and fabricated. This device exhibits good switching and gate control capabilities.
By connecting the devices in antiparallel, a heterojunction device with bidirectional
switching characteristics can be obtained. With either polarity of the voltage applied
to the anode, the same switching behavior of this device is obtained, which is suitable for ac switch applications.
Comparison of Defect Annealing Kinetics of a-Si:H Prepared by Pure Silane and Helium Diluted Silane by Triode Plasma Chemical Vapour Deposition
Authors: Osborne Ian S. , Nobuhiro Hata Nobuhiro Hata , Akihisa Matsuda Akihisa Matsuda
Published: October 2002

We have compared the defect annealing kinetics of hydrogenated amorphous silicon films
(a-Si:H) prepared by triode deposition using pure silane and silane diluted with helium.
Analysing the defect annealing kinetics with a defect pool having a gaussian distribution
of annealing energies, the peak of the defect annealing energy distributions for the
films deposited with helium diluted silane are shifted to higher energy, which reflect
films of poorer stability. Furthermore, for a given deposition process, the distribution
of the annealing energies is sensitive to the deposition parameters. Once the pool
parameters have been determined, the long term light-soaking behaviour of the films for any intensity can be predicted.
Optical Properties of InGaAsP Multiple Quantum Well Edge-Emitting Light-Emitting Diode
Authors: Kashima Yasumasa , Matoba Akio , Takano Hiroshi , Kanie Hisashi , Irie Taizo
Published: October 2002

Effects of the number of wells on the characteristics of a 1.3-µ m edge-emitting
light-emitting diode (LED) are investigated. The edge-emitting LED with 10 quantum wells
had the highest optical output power at 100 mA and the lowest temperature coefficient
of the optical output power in the temperature range from 10 to 75°C. The
experimental result shows that the multiple quantum well structure improves the thermal
stability of the optical output power.
Preparation of PbTiO3 Thin Films by Screen Printing Method
Authors: Tomoaki Futakuchi Tomoaki Futakuchi , Katsumi Tanino Katsumi Tanino
Published: October 2002

PbTiO3 thin films were obtained by the screen printing method on Au bottom
electrodes using Si(100) substrates. The screen-printable paste was synthesized from the
Pb–Ti complex alkoxide and abietic acid. The optimum conditions of amount of PbO content
in the paste and annealing temperature were investigated to prepare the ferroelectric thin film.
The remanent polarization and coercive field of this thin film were 8 µ C/cm2
and 110 kV/cm, respectively. Pyroelectric coefficient was 0.67× 10-8 (C/cm2·K) after poling.
Presence of In-Plane Orientation in Single Azobenzene Monolayers by Maxwell-Displacement-Current Measurement
Authors: Mitsumasa Iwamoto Mitsumasa Iwamoto , Yuichiro Kanai Yuichiro Kanai
Published: October 2002

The presence of in-plane orientation of azobenzene molecules in single monolayers
of polymer films was detected by means of Maxwell-displacement-current (MDC) measurement
with linearly polarized photoirradiation. The magnitude of MDC generated by photoirradiation
polarized in a direction parallel to the dipping direction of the azobenzene monolayer
was greater than that generated by photoirradiation normal to the dipping direction.
The in-plane orientational change in azobenzene molecules in single polymeric monolayers
was produced as a result of alternating polarized photoirradiation of UV and visible
light for a sufficiently long time, and it was also detected by means of MDC measurement.
Analysis of the Change in the Carrier Concentration of SnO2 Thin Film Gas Sensor
Authors: Kanamori Masaaki , Suzuki Kiyohiro , Yutaka Ohya Yutaka Ohya , Yasutaka Takahashi Yasutaka Takahashi
Published: October 2002

Electrical properties and the number of unpaired electrons localized in oxygen vacancies of SnO2 thin films
were quantitatively analyzed using the van der Pauw method and ESR spectra, respectively, in order to clarify
the source of carrier electrons induced on gas sensing. The concentration of carriers generated was related to
the amount of unpaired electrons localized in oxygen vacancies which were produced under the flammable gas
atmosphere. No adsorbed oxygen was detected by ESR. From these results it is concluded that most of the
carrier electrons were supplied not from adsorbed oxygen on SnO2 surface but from oxygen vacancies of the SnO2 surface layer.
Method of Designing Phase-Shifting Masks Utilizing a Compactor
Authors: Ooi Kazuko , Kiryu Kiyomi Koyama
Published: October 2002

A new method is proposed for designing Levenson-type phase-shifting masks. In this method, phases are
assigned in an intermediate layout, and then the intermediate layout is converted to a final layout. In practice,
the intermediate layout is a symbolic layout, and the symbolic layout is converted to a mask layout by a compactor.
According to the strategy, no conflict spots arise during the operation, which greatly improves design efficiency.
This design method is applicable to random patterns in a memory peripheral circuit and in microcomputer chips.
As a result of application to the peripheral circuit of dynamic random access memory (DRAM), about 16%
shrinkage of the mask area was obtained, compared with a conventional mask. As for a microcomputer chip, 12%
shrinkage of mask area was obtained under the condition of 50% shrinkage of aluminum-wire spacing. Together
with the interactive method reported before, which is applicable to a memory core circuit, the design of the
Levenson-type masks for standard LSIs is totally covered.
0.13 µm Pattern Delineation Using KrF Excimer Laser Light
Authors: Imai Akira , Asai Naoko , Ueno Takumi , Hasegawa Norio , Tanaka Toshihiko , Tsuneo Terasawa Tsuneo Terasawa , Shinji Okazaki Shinji Okazaki
Published: October 2002

This paper investigates the resolution limit of KrF excimer laser lithography using phase-shifting mask (PSM)
technology by simulation and experiment. An improved phase-shifting mask structure combined with a newly
developed crosslinking type negative-tone resist on a reflection-suppressed trilayer resist makes it possible to
delineate minimum pattern size of 0.13 µm with sufficient depth of focus, using a high-NA lens system under
high coherent light. These results show that KrF excimer laser lithography applying PSM technology is a good
candidate for gigabit-level ULSI fabrication by lithography.
Identification of Generation-Recombination Centers and Traps in Virgin and Fowler-Nordheim Stressed Metal-Oxide-Semiconductor Field-Effect Transistors by Low Temperature Charge Pumping Technique
Authors: Jen-Tai Hsu Jen-Tai Hsu , C. R. Viswanathan C. R. Viswanathan
Published: October 2002

Low temperature charge pumping (CP) current measurements were carried out on 100 µm/10 µm N-channel metal-oxide-semiconductor (NMOS) transistors to investigate the interface state density. Interface states comprise traps and generation-recombination (g-r) centers. By measuring the CP current at different pulse frequencies at low temperatures, where the emission time constant of the traps is larger, the distribution of traps is determined distinct from that of the g-r centers. The formation of traps and g-r centers due to Fowler-Nordheim (F-N) injection at 77 K was studied by using this technique. It was shown that, immediately after the stress, F-N stress at 77 K creates more traps than g-r centers. When the temperature was raised to room temperature following stress at 77 K, the transformation from traps to g-r centers was observed. In alternating positive and negative F-N stress, positive F-N stress anneal out some of the traps generated during the previous negative F-N stress.
Patterning Accuracy Estimation of Electron Beam Direct-Writing System EX-8D
Authors: Hattori Kiyoshi , Magoshi Shunko , Sunaoshi Hitoshi , Wada Hirotsugu , Ando Atsushi , Yamaguchi Toshio , Mikami Shinji , Nishimura Shinsuke , Housai Hiroaki , Hashimoto Susumu , Ryoichi Yoshikawa Ryoichi Yoshikawa , Tadahiro Takigawa Tadahiro Takigawa
Published: October 2002

Self-diagnosis functions related to patterning accuracy are important techniques for
developing, improving and maintaining electron beam exposure systems. An evaluation
method of beam position deviation has been developed to reduce fluctuation of patterning
accuracy. High-frequency beam position deviation was detected by scanning the beam on a W
mark with subsequent fast fourier transform analysis. A magnetic field compensator has
been developed to reduce low-frequency beam position deviations induced by ambient
magnetic field changes. The beam position deviations of high- and low-frequency have
been restricted to about 17 nm (3σ). A mark stand, which carries a height-changeable
mechanism, was developed to calibrate the beam deflection accuracy depending on the Z direction.
By applying the above diagnostic function, a main frame stitching accuracy of 32 nm has
been achieved with short turnaround time.
Polarization Dependence of Electric Field Intensity Distributions in Photoresist Films
Authors: Tanabe Hiroyoshi , Inui Hirotomo , Yukio Ogura Yukio Ogura , Shunji Kishida Shunji Kishida
Published: October 2002

The polarization dependence of the electric field intensity distributions in photoresist films has been studied
by simulation. S-polarized illumination produces higher image contrast than P-polarized illumination in air.
However, due to the high refractive indices of photoresist films, the difference of the image contrasts formed by
S- and P-polarized illuminations almost disappears in the photoresist films. The reflectivities from nonplanar
substrates strongly depend on the polarization of illumination. The reflection from nonplanar substrates can be
strongly suppressed by using P-polarized illumination.
Surface Reaction Induced by Multiply-Charged Ions
Authors: Mochiji Kozo , Itabashi Naoshi , Yamamoto Seiji , Okuno Isao Ochiai
Published: October 2002

The surface reactions induced by an electronic potential energy of multiply-charged ions are investigated. A small electron-beam impact type ion source for production of multiply-charged ions was manufactured for this study. The charge state distribution of multiply-charged ions produced in the ion source greatly depends on the sample gas pressure and the potential barrier for ion trapping. In operation with an electron current of 7 mA at 2 keV, the ion-beam currents obtained for Ar5+and Ar10+are respectively at least 7 pA and 2× 10-3pA. H+ion desorption from a lightly etched GaAs surface are observed by bombarding with Arq+ions (q=1–3). The desorption yield of H+per Arq+increases proportionally with the sixth power of the charge state of Arq+. This charge state effect is discussed from the viewpoint of the electronic interaction between the GaAs surface and Arq+ions.
Radical-Beam-Induced Surface Reaction Processes of Porous Si
Authors: O'Keeffe Patrick , Komuro Shuji , Kato Takashi , Morikawa Takitaro , Yoshinobu Aoyagi Yoshinobu Aoyagi
Published: October 2002

A new-low temperature dry oxidation process, unlike the presently used methods of
wet chemical processing or high-temperature rapid thermal annealing, for the oxidation
of porous silicon (PS) is described. In this process the active oxygen radical species
from an electron cyclotron resonance plasma were employed for the first time to achieve
room-temperature oxidation of PS. This process allows manipulation of the PS surface
chemistry which has resulted in both the enhancement and stabilization of the photoluminescence
(PL) intensity. These results are explained on the basis of a proposed model in which
surface-induced processes incorporate oxygen atoms not only in the outermost Si–O–Si
layer but also in the backbonded Si of PS. Furthermore, it is shown that this backbond
oxidation is the main mechanism responsible for the enhancement and stabilization of the PL intensity.
Step Motion and Structure Transition on InAs and GaAs (001) Surfaces Observed by Scanning Tunneling Microscopy
Authors: Hiroshi Yamaguchi Hiroshi Yamaguchi , Yoshiji Horikoshi Yoshiji Horikoshi
Published: October 2002

The step motion and structure transition on InAs and GaAs (001) surfaces are directly observed by scanning tunneling microscopy at high temperatures. A stable (2×4) structure is observed for the InAs surface even at temperatures high enough to cause the motion of monomolecular steps and kinks. At higher temperatures, domains with an In stable (4×2) structure (As desorbed region) are clearly observed surrounded by As stable (2×4) structures. These results differ from those for GaAs surfaces and indicate strong lateral interaction in (2×4) structures on InAs.
Fabrication of Cantilever with Ultrasharp and High-Aspect-Ratio Stylus for Scanning Maxwell-Stress Microscopy
Authors: Itoh Junji , Tohma Yasushi , Inoue Takahito , Hiroshi Yokoyama Hiroshi Yokoyama , Keizo Shimizu Keizo Shimizu
Published: October 2002

A cantilever with an ultrasharp and high-aspect-ratio stylus was made by using a
directly bonded silicon-on-insulator (SOI) wafer. The stylus and cantilever were made of
8-µ m-thick Si film and 2-µ m-thick SiO2
film of SOI with sufficient reproducibility. The cantilever is 100 µ m in length,
20 µ m in width and 1.6 µ m in thickness, and the stylus, 7 µ m
in height with an aspect ratio exceeding 2. The apex of the stylus is about 5 nm in radius
of curvature. The present cantilever was applied to scanning Maxwell-stress microscopy (SMM),
and spatial resolution of about 10 nm was achieved in surface potential images of the
metal surface, which was significantly better than that obtained with a commercially available
conventional cantilever. The fabrication sequence, mechanical properties of the cantilever
and results of SMM measurements are discussed.
Fabrication of Superconducting Transistors using InAs/(AlGa)Sb Quantum Wells
Authors: Maemoto Toshihiko , Dobashi Hiroyuki , Izumiya Satoshi , Kanji Yoh Kanji Yoh , Masataka Inoue Masataka Inoue
Published: October 2002

We report on a fabrication process of superconducting weak links and superconducting
transistors, which contain two-dimensional electrons in InAs/(AlGa)Sb quantum well.
The superconducting transistors with lead alloy superconducting contacts were fabricated
by using electron beam lithography, lift-off, and wet chemical etching processes.
We have succeeded in fabricating a superconducting transistor with 0.4 µ m
channel length and 0.17 µ m gate length between superconducting electrodes.
Although the ideal performance of superconducting transistors has not been achieved yet,
we present the results of superconducting weak links. The process of reducing contact
resistance between lead alloy and InAs is also discussed, which is crucial to demonstrate
the performance of the superconducting transistor.
Mechanism of Multiatomic Step Formation during Metalorganic Chemical Vapor deposition Growth of GaAs on (001) Vicinal Surface Studied by Atomic Force Microscopy
Authors: Ishizaki Jun-ya , Goto Shu , Kishida Motoya , Fukui Takashi , Hasegawa Hideki
Published: October 2002

The detailed behavior and mechanism of multiatomic step formation processes during metalorganic chemical vapor deposition (MOCVD) of GaAs on vicinal surfaces are systematically investigated using an atomic force microscope (AFM). Under the low growth rate condition, the step flow growth mode with regular stripe is obtained, and the final terrace width is almost independent of the substrate misorientation angle. The result suggests that the barrier height difference for surface migrating Ga atoms between the terrace site and the step site is small, and the final terrace width is mainly determined by a migration length. Three-dimensional nucleation and growth mode with irregular steps are also obtained under the high growth rate condition. However, as the AsH3 partial pressure increases, irregular steps are no longer observed. For these results, we discuss the multiatomic step formation mechanism.
0.05-µ m-Gate InAlAs/InGaAs High Electron Mobility Transistor and Reduction of Its Short-Channel Effects
Authors: Enoki Takatomo , Tomizawa Masaaki , Yohtaro Umeda Yohtaro Umeda , Yasunobu Ishii Yasunobu Ishii
Published: October 2002

In this paper, we discusse the advantages of thinning the channel on short-channel effects for lattice-matched InAlAs/InGaAs high electron mobility transistors (HEMTs) with sub-0.1-µm-long gates with regard to the performance of a 0.05-µm-gate device. To fabricate a sub-0.1-µm gate, the opening shape of the gate-footprint is controlled by using a bilayer dielectric film system and RIE side etching. The device shows a current gain cutoff frequency of 300 GHz and g
m/g
d ratio of 15. Thinning the channel and the barrier down to 100 Å improves carrier confinement and subthreshold characteristics and is indispensable for reducing the short-channel effects in the sub-0.1-µm-gate-length region.
Operation of 780 nm AlGaAs Distributed Feedback Lasers at 100°C with Low-Loss Waveguide Structure
Authors: Inoguchi Kazuhiko , Kudo Hiroaki , Sugahara Satoshi , Ito Shigetoshi , Hisaharu Yagi Hisaharu Yagi , Haruhisa Takiguchi Haruhisa Takiguchi
Published: October 2002

Stable single-mode operation of 780 nm wavelength was obtained with AlGaAs distributed feedback (DFB) lasers grown by metal organic chemical vapor deposition (MOCVD) and liquid-phase epitaxy (LPE). To achieve both high-temperature and broad-range temperature single-mode operation, we propose a new type of low-loss waveguide (LLG) structure and the use of trapezoid-shaped third-order corrugation. The devices showed a wide range of operating temperature up to 100° C, output power of 10 mW cw operation even at 100° C, high side-mode suppression ratio of more than 30 dB, and wide fixed single-mode operation temperature range of more than 90 degrees. We have confirmed that these AlGaAs DFB lasers are applicable to holographic laser beam printers or scanners.
Fabrication of InGaAs Wires by Preferential Molecular Beam Epitaxy Growth on Corrugated InP Substrate
Authors: Fujikura Hajime , Iwa-ana Tadayoshi , Hasegawa Hideki
Published: October 2002

Fabrication technology of InGaAs wire structures by preferential molecular beam epitaxy growth on corrugated InP substrate was successfully developed for the first time. Growth was made on the substrates having V-grooves with (211)A or (111)A facets and wires were made in nonquantum regime. The effects of the growth conditions on the cross-sectional structure and photoluminescence (PL) properties were clarified. Wires grown on (111)A facets showed better structural and PL properties than those on (211)A facets. Insertion of an InGaAs low-temperature (LT) buffer layer was found to greatly improve the band-edge PL intensity. Under optimum conditions, the wire exhibited an intense PL emission with a narrow peak width at an energy position of InGaAs lattice-matched to InP. A defect-related emission is also observed and discussed.
In-plane Orientation and Coincidence Site Lattice Relation of Bi2Sr2CaCu2Ox Thin Films Formed on Highly Mismatched (001) YAG Substrates
Authors: Kataoka Masayuki , Kuroda Ken'ichi , Oishi Toshiyuki , Takami Tetsuya , Furukawa Akihiko , Tanimura Junji , Ogama Tetsuo , Kazuyoshi Kojima Kazuyoshi Kojima
Published: October 2002

The symmetry-related in-plane misorientation is investigated in an highly mismatched system of (001) Bi2Sr2CaCu2O

x

(2212) thin films on (001) cubic substrates with 12 Å lattice length. Irregular in-plane orientation of 2212[510]// Sub.[120] is expected on the basis of the coincidence site lattice theory. This expectation is realized using (001)YAG (yttrium aluminium garnet) substrates. The atomic structure model is shown with regard to the interface between (001)2212 film and the (001)YAG surface.
Temperature and Gate Bias Effects on Gamma-Irradiated Al-Gate Metal-Oxide-Semiconductor Transistors
Authors: Pejović Momčilo , Golubović Snežana , Odalović Goran Ristić
Published: October 2002

The annealing of irradiated Al-gate metal-oxide-semiconductor (MOS) transistors at elevated temperature ( 115°C), without gate bias for P-channel metal-oxide-semiconductor (PMOS) transistors, and with/without gate bias (+9 V) for N-channel metal-oxide-semiconductor (NMOS) transistors, has been investigated. The experimental data obtained are analyzed in terms of physicochemical and electrophysical processes responsible for creation of gate oxide charge and interface traps, as well as their anneal. The decrease of positive charge density in irradiated transistors during thermal annealing is caused by electrons tunneling from the silicon into the oxide. The rate of neutralization of positive centers depends on the irradiation dose level.
Hydrogen-Induced Ag Cluster Formation on the Si(111) √ 3×√ 3(R30°)-Ag Surface Observed by Scanning Tunneling Microscopy
Authors: Ohnishi Hideaki , Yamamoto Yasuji , Katayama Itsuo , Ohba Yasuyuki , Kenjiro Oura Kenjiro Oura
Published: October 2002

The scanning tunneling microscope (STM) has been used to study structural transformation of the Si(111) √ 3×√ 3(R30°)–Ag surface caused by atomic hydrogen adsorption. When atomic hydrogen adsorbs on the √ 3-Ag surface, the Ag atoms are expelled to form clusters. The size of the Ag clusters has been confirmed to be less than 150 Å in agreement with previous ion scattering results. Spatial distributions of the clusters, observed as functions of the exposure to atomic hydrogen, reveal that surface diffusion of Ag atoms over the hydrogen-covered regions is largely suppressed compared with that on the √ 3-Ag surface. The clusters are hexagonal and their orientations suggest the formation of Ag(111) clusters.
Low Thermal Budget Polycrystalline Silicon-Germanium Thin-Film Transistors Fabricated by Rapid Thermal Annealing
Authors: Jurichich Steve , King Tsu-Jae , Mehlhaff Krishna Saraswat
Published: October 2002

A low temperature ( ≤600°C) and short time polycrystalline silicon-germanium thin-film transistor technology is demonstrated. The use of rapid thermal annealing for channel crystallization and dopant activation allows for shorter anneal times and thus higher throughputs than with conventional furnace annealing. Moreover, the use of silicon-germanium allows for lower process temperatures to be used than is required for silicon thus leading to minimal shrinkage and warpage, and enabling this technology to be compatible with large-area glass substrates.
Corrugated Structures on Si(110) Surfaces Treated in Ammonium Fluoride Solutions
Authors: Ken Fujita Ken Fujita , Norio Hirashita Norio Hirashita
Published: October 2002

We have investigated structures on Si (110) surfaces treated in ammonium fluoride solutions using infrared light absorption spectroscopy and reflection high-energy electron diffraction. It has been found that the surface is smoothed along the [11̄0] direction, while corrugation remains across the [11̄0] direction on an atomic scale. The surface has been found to be terminated by coupled monohydride with the same stretch vibration frequency of monohydride at step edges on vicinal Si (111) surfaces. The absorption coefficient of coupled monohydride has been compared to that of uncoupled monohydride on Si (111) terraces.
Photorefractive Color Converter Making Use of Beam Fanning Effect
Authors: Lee Hsiao-Yi , Hon-Fai Yau Hon-Fai Yau , Sha-Wei Wang Sha-Wei Wang
Published: October 2002

We have demonstrated a setup using a BaTiO3 crystal which functions as either a color converter or an incoherent-to-coherent converter, depending on whether the input pattern is carried by a coherent or an incoherent beam. There are two beams of light involved in the experiment: a pattern-carrying beam and a pattern-grabbing beam. The setup operates on the principle that the noise gratings formed by the pattern-grabbing beam and its scattered waves in the photorefractive crystal are erased by the input pattern. As a result, the setup behaves as a transmission spatial light modulator, and the output patterns are positive replicas of the input patterns.
Broad-Band Second-Harmonic Generation in LiNbO3 Waveguide Using Optimized Domain-Inverted Grating
Authors: Jie Wu Jie Wu , Chang-Qing Xu Chang-Qing Xu , Hideaki Okayama Hideaki Okayama , Masahito Kawahara Masahito Kawahara , Takashi Kondo Takashi Kondo , Ryoichi Ito Ryoichi Ito
Published: October 2002

We demonstrate broad-band second-harmonic generation in a quasi-phase-matched LiNbO3 waveguide, with a window bandwidth as large as 13nm and a conversion efficiency up to 29%/W. Such a large bandwidth is achieved using an aperiodic domain-inverted grating structure optimized by simulated annealing.
Suppression of Washer Resonance of DC Superconducting Quantum Interference Device by Using New Washer with Additional Slit
Authors: Shimizu Nobuhiro , Enpuku Toshimitsu Morooka
Published: October 2002

A DC superconducting quantum interference device (SQUID) using a new washer with an additional slit has been designed and fabricated in order to investigate the washer resonance of the SQUID coupled to a multiturn input coil. Current steps in I-V curves, which reflect the degree of washer resonance, are compared for the new and conventional washers. It is shown that the resonant step of the coupled SQUID is weakened much more with increasing length of the additional slit. This result agrees with simulation results, and confirms the usefulness of the new washer for the suppression of washer resonance.
Lasing at 352 nm of the NIJI-IV Storage-Ring Free-Electron Laser
Authors: Yamazaki Tetsuo , Yamada Kawakatsu , Sei Norihiro , Ohgaki Hideaki , Kawai Masayuki , Yokoyama Minoru , Hamada Shinji , Sugiyama Suguru , Mikado Tomohisa , Suzuki Ryoichi , Noguchi Tsutomu , Iwata Mitsukuni Chiwaki
Published: October 2002

Lasing at 352 nm of the “NIJI-IV” storage-ring free-electron laser (FEL) was successfully achieved on the 28th of April, 1994. To our knowledge, this is the first FEL oscillation on a compact storage ring in the ultraviolet wavelength region. The electron-beam energy was 311 MeV, and the beam current was 10∼6 mA/bunch. The fluctuation of the macro-temporal strvcture was smaller than that observed before in the case of oscillation in the visible wavelength region. The improvements made on the ring since 1993 proved to be quite effective for the shorter-wavelength FELs.
Growth Processes of GaAs Grown by Atomic Layer Epitaxy Revealed by Atomic Force Microscopy
Authors: Yokoyama Haruki , Tanimoto Masafumi , Masanori Shinohara Masanori Shinohara , Naohisa Inoue Naohisa Inoue
Published: October 2002

The growth processes of GaAs grown by atomic layer epitaxy (ALE) are examined on an atomic scale using atomic force microscopy (AFM). The examination reveals that two-dimensional (2-D) nucleation and step-propagation growth take place simultaneously under ALE growth conditions. The critical terrace width below which only step-propagation growth occurs is 300–600 nm in spite of the low growth temperature. This is two to three orders of magnitude larger than the values for molecular beam epitaxy and metalorganic chemical vapor deposition extrapolated to the ALE temperature. It is assumed that the migration of the undecomposed TMG on an As-stabilized surface is responsible for the large critical terrace width in ALE.
Relationship between Electrical Conductivity and Charged- Dangling-Bond Density in Nitrogen- and Phosphorus-Doped Hydrogenated Amorphous Silicon
Authors: Masuda Atsushi , Itoh Ken-ichi , Zhou Jiang-Huai , Kumeda Minoru , Tatsuo Shimizu Tatsuo Shimizu
Published: October 2002

Comparing the results for nitrogen doping in hydrogenated amorphous silicon ( a-Si:H) with those for phosphorus doping, the increase in the charged-dangling-bond density estimated by equilibrium electron spin resonance (ESR) and light-induced ESR is found to have no apparent correlation with the increase in the electrical conductivity. The results for varying concentrations of nitrogen doping are also consistent with this finding. The increase of potential fluctuations due to structural disorder by nitrogen doping in an a-Si:H network appears to be the dominant origin of the increase of charged dangling bonds in the case of nitrogen doping.