bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of SF6 Addition to O2 Plasma on Polyimide Etching
Authors: Kim Sang Hoon , Woo Sang-Gyun , Ahn Jinho
Published: October 2002

For further scaling down of silicon devices, the application of low-k interlayer dielectrics instead of silicon oxide has been considered to reduce power consumption, crosstalk and interconnection delay. In this paper, the effect of SF6/O2 plasma chemistry on the etching characteristics of polyimide has been studied using a electron cyclotron resonance (ECR) plasma etching system. Addition of SF6 gas results in a very smooth etched surface even though this causes a reduced etch rate due to the formation of nonvolatile fluorine compounds inhibiting the reaction between oxygen and hydrocarbon polymers. However, the etch rate can be compensated by applying a substrate bias or increasing the microwave power. As a result, 1–2 µm line and space patterns were successfully obtained using a SiO2 hard mask.
Plasma Treatment and Dry Etch Characteristics of Organic Low-k Dielectrics
Authors: Wei Ta-Chin , Liu Chi-Hung , Shieh Jia-Ming , Suen Shich-Chang , Dai Bau-Tong
Published: October 2002

In this study, the effect of plasma treatment on the low-k material FLARE 2.0 (FLARE is a trademark of Honeywell) was investigated. It was found that the leakage current of FLARE 2.0 was drastically reduced after brief plasma treatments. The moisture-absorption ability was reduced by CF4 plasma treatment, whereas following H2 and N2 plasma treatments, the moisture-absorption ability was increased. The increased moisture uptake did not affect the dielectric property of FLARE 2.0. The dry etch characteristics of FLARE 2.0 in helicon-wave high-density oxygen plasmas were also studied. The etch rate and selectivity to oxide can be controlled by bias power and the addition of CHF3 or N2.
Initial Oxidation of Si(001) Induced by the Translational Kinetic Energy of O2 Supersonic Molecular Beams
Authors: Yoshigoe Akitaka , Sano Mutsumi , Teraoka Yuden
Published: October 2002

The influence of the variation of up to 3.0 eV in the incident translational kinetic energy of O2 (E

t
) on the chemisorption of O2 onto Si(001) surfaces was studied by using the supersonic molecular beam (SSMB), X-ray photoemission spectroscopy (XPS), O2 molecular scattering and desorbed SiO detection techniques. Under passive oxidation conditions at room temperature, the amount of saturated oxygen on the Si(001) surface was enhanced in concomitant with an increase in the translational kinetic energy of O2. Threshold energies, corresponding to potential energy barriers for the direct oxidation reaction, are clearly observed at E

t
=1.0 eV and E

t
=2.6 eV. These threshold energies have been assigned to backbond oxidation of the Si dimer atoms and oxidation between the second and the third Si layers, respectively. Futhermore, at substrate temperature of 700°C, the relative desorption rate of SiO was increased when the translational kinetic energy of O2 was greater than E

t
=1.0 eV. These results suggest that the oxidized Si dimer backbond is the precursor for the desorbed SiO.
Combining Atomic Force Microscopic Lithography with Photolithography
Authors: Ishibashi Masayoshi , Heike Seiji , Hashizume Tomihiro
Published: October 2002

We developed a method that combines atomic force microscopic (AFM) lithography with photolithography. This method uses small-step structures on the resist surface, fabricated by slight development, to align the patterns produced by photolithography and AFM lithography. We used this hybrid method to fabricate narrow wire patterns that led to large contact-pad patterns and demonstrated it's effectiveness at reducing drawing time and lengths.
Equalizer Design Based on Diffraction Analysis
Authors: Honguh Yoshinori
Published: October 2002

A design procedure is described that determines the optimum frequency characteristics of
an equalizer, considering the intersymbol interference (ISI) and crosstalk, under the influence
of the tilt of the disk substrate. A scalar-wave diffraction model was employed to calculate
the readout signals. A finite impulse response (FIR) filter was assumed for the equalizer. The jitter was calculated as a function of the equalizer parameters, and the equalizer parameters were determined so that the calculated jitter took its
minimum value.
The entire process of the equalizer design was performed on an computer, and the resultant
characteristics were similar to those determined through experiments. Therefore, the
method provides a useful tool for the basic design of optical disk
systems.
Imprint Characteristics by Photo-Induced Solidification of Liquid Polymer
Authors: Komuro Masanori , Taniguchi Jun , Inoue Seiji , Kimura Naoya , Tokano Yuji , Hiroshima Hiroshi , Matsui Shinji
Published: October 2002

Nanoimprint lithography is an attractive technology for LSIs era below 40-nm critical dimension from the viewpoints of high-throughput and low-cost equipment. In order to avoid a pattern placement error due to thermal expansion in the conventional thermal imprint process, we attempted to replicate the mold pattern onto a liquid polymer, which was solidified using ultra-violet (UV) light irradiation at room temperature. The liquid polymer used here was supplied by TEIJIN SEIKI Co., and termed TSR-820. It was spin coated on slide glass to produce approximately 1.5-µm-thick polymer film. The thickness remained after UV exposure and rinsing in acetone was observed at the dose of 10 J/cm2 and it saturated about a UV exposure dose of 100 J/cm2 with an increase in the exposure dose. The mold fabricated of quartz plate was first pressed onto the polymer film at about 100 kg/cm2 and then the UV light was irradiated using an imprint apparatus developed for this work. After releasing the mold from the film, the substrate was rinsed in acetone to remove the residual liquid polymer. Eventually the minimum feature size of 100-nm line and 300-nm space pattern was successfully replicated in the polymer with good fidelity.
Design and Fabrication of Electromagnetic Micromirror with Bulk Silicon Mirror Plate and Aluminum Spring
Authors: Ji Chang-Hyeon , Kim Yong-Kweon , Chung Gyo-Bum
Published: October 2002

We have designed and fabricated an electromagnetic micromirror with a flat mirror plate capable of large angular deflection. Single-crystal silicon is used as a mirror plate to obtain an optically flat reflective surface. By a combination of surface and bulk micromachining processes, the single-crystal silicon mirror plate is connected to the substrate via an aluminum spring, which occupies a relatively small area without compromising the compliance. The proposed fabrication process can be applied to the fabrication of devices in which a flat moving part is supported by a compliant spring structure. Nickel electroplated onto the mirror plate enables a mirror rotation angle of up to 84.8° by applying an external magnetic field vertical to the substrate. This designed structure can be used individually or as an array in microphotonic applications.
Applying an Objective Lens of 0.7-Numerical Aperture to a Center-Aperture-Detection Type of Magnetically Induced Superresolution Disk
Authors: Tanaka Yasuhito , Watanabe Tetsu , Shinoda Masataka , Shimouma Takashi , Murakami Yoshiteru , Takahashi Akira
Published: October 2002

We studied the performance of the center-aperture-detection type
of magnetically induced superresolution (CAD-MSR) disk using an
objective lens with a numerical aperture (NA) of 0.7. We
confirmed the practicability of a 10 Gbyte user capacity and the feasibility
of an 11.5 Gbyte user capacity on a 120-mm-sized disk by the
evaluation of the system margins. We also evaluated system margins
by using an objective lens with an NA of 0.6. We have confirmed that
the performance of the CAD-MSR disk depends on the NA of the
objective lens.
Suppression of Jitter Bump GeSbTe Phase-Change Optical Disk
Authors: Jeong Tae Hee , Seo Hun , Yeon Cheong , Park Jeong Woo , Lee Jeong Soo , Park Kyu Ho
Published: October 2002

The origin of a jitter bump for phase-change optical disks was analyzed by transmission electron microscopy. The origin of a jitter bump is closely related to the crystallization rate, which is initially not sufficiently fast to match the linear velocity of the disk, resulting in the previous mark remaining as a tail. The jitter bump was markedly suppressed by adding oxygen-doped GeSbTe film between the recording layer and the dielectric layer.
Approach for High Speed Recording of 4.7 GB Digital Versatile Disc-Recordable
Authors: Fujii Toru , Tajima Toshiaki , Negishi Ryo , Okitsu Isao , Tomizawa Yuji , Matsuda Isao , Hamada Emiko
Published: October 2002

The demand for digital versatile disc-recordable (DVD-R) is currently undergoing explosive growth and both higher speed
recording and higher density are required. This paper examines the
potential for achieving 4x-speed recording on 4.7 GB DVD-R media. 1x-speed and 2x-speed recording are examined experimentally and by computer
simulation, and actual recorded signals are found to be in good agreement with predictions
based on computer simulation of thermal interference profiles. Based on these results, the heat
design technology needed to realize high speed recording is identified and the potential for
4x-speed recording is demonstrated theoretically.
Ten-Year Overview and Future Prospects of Write-Once Organic Recordable Media
Authors: Hamada Emiko , Takagishi Yoshikazu , Yoshizawa Takanori , Fujii Toru , Negishi Ryo , Nakajima Takeshi
Published: October 2002

The CD-R market has grown rapidly since
the development of this
media in 1988. In addition, PC applications have continued to demand
ever higher recording speeds. In order to achieve higher speed
recording, it is necessary to reduce thermal interference during the
recording process. Higher density recording is subject to the same
effects of thermal interference as higher speed recording. To
directly compare such thermal effects during recording on different
density disks with different scanning velocities, we introduce a new
parameter. Applying this parameter, it can be clearly demonstrated
that thermal interference in higher density digital versatile
disc-recordable (DVD-Rs) is approximately
equal to that in 8x-speed recording with the lower density
CD-R. Today, the possibility of 4x-speed DVD-R recording has already
been confirmed. It can thus be concluded that write-once organic
recordable media with
a 15 GB capacity per 12 cm diameter disk format is very promising,
because the thermal effects associated with the 15 GB recordable media
are shown to be equivalent to those in 4x-speed DVD-R.
Fast-Access Optical Drive
Authors: J. Niessen Jeroen Wals , M. G. Rijs Marcel Rieck
Published: October 2002

A slim-line linear motor is presented for fast access in optical drives. By applying a three-phase commuting
linear motor in combination with a split-optical head, an average seek time of 11 ms is realised for a 120-mm optical
disc. The rotational latency is reduced by spinning the disc at 100 Hz, resulting in a total average access time of 25 ms. Two-stage radial tracking is applied, along with a one-dimensional lens actuator to attain high mechanical bandwidths. In addition, a novel scheme for counting tracks during high-speed access is proposed.
Optical Pickup Employing a Hologram-Laser-Photodiode Unit
Authors: Yoshida Shinya , Minami Kohji , Okada Kuniaki , Yamamoto Hiroyuki , Ueyama Tetsuo , Sakai Keiji , Kurata Yukio
Published: October 2002

In this paper we review the holographic optical element technology
applied to compact disc (CD), digital versatile disc (DVD) and mini disc (MD) pickups. Using this technology, the number of optical components and the size and
weight of a CD pickup are successfully reduced and its reliability is improved,
because many functions of the optical components are integrated into a
hologram-laser-photodiode unit. For DVD application, the focus detection for a
dual-layer disk and the differential phase detection (DPD) method are realized by
the hologram technology. Our unique two-segment DPD method shows more
stable characteristics than the conventional DPD method. An integrated MD
hologram pickup is also developed with an optical waveguide device that functions
in magneto optical (MO) signal detection.
Numerical Analysis of Type I Third-Harmonic Generation through Third-Order and Cascaded Second-Order Nonlinear Optical Processes
Authors: Zhang Tiejun , Yamakawa Koichi
Published: October 2002

We report on the numerical analysis of type I third-harmonic
generation of ultrashort pulse lasers through third-order and cascaded
second-order nonlinear optical processes. We derive a set of wave
equations which includes group-velocity mismatch, group-velocity
dispersion, and depletion of the fundamental pulse, and carry out
numerical calculations for a type I β-barium borate (BBO)
crystal with an 800 nm fundamental wavelength and a 100 fs pulse
duration. Numerical results show that the third-harmonic pulse is
temporally broadened and changes shape from a Gaussian to a
super-Gaussian profile due to the group-velocity mismatch, and the
third-harmonic intensity is approximately proportional to the cube of
the initial fundamental intensity.
Optical Disk Recording Using a GaN Blue-Violet Laser Diode
Authors: Ichimura Isao , Maeda Fumisada , Osato Kiyoshi , Yamamoto Kenji , Kasami Yutaka
Published: October 2002

The combination of a GaN laser diode and a 0.85 numerical aperture objective has
achieved an optical storage capacity of over 22 GB. Owing to sufficient modulation ability
and low-noise characteristics, GaN semiconductor lasers possess adequate quality to be light
sources in optical recording systems. A bit size of
130 nm×300 nm, corresponding to the
areal recording density of 16.5 Gbit/in.2, was realized on a six-layered thin-cover
phase-change disk with a crystallization-promoting structure. Each active layer was
inversely stacked and was thermally as well as optically optimized for the blue-violet light
sources. A new small electromagnetic actuator with a lightweight φ3 mm two-element
lens has extended its servo-bandwidth up to 8 kHz and enabled precise focusing control at the
data transfer rate of 35 Mbps.
The Characteristics and the Potential of Super Resolution Near-Field Structure
Authors: Tominaga Junji , Fuji Hiroshi , Sato Akira , Nakano Takashi , Atoda Nobufumi
Published: October 2002

The superresolution near-field structure (super-RENS) was proposed as an
alternative optical near-field recording technique last year. In this paper, our approach
and the basic principle of super-RENS are briefly reviewed, and the recent results
obtained by our group are described. As a result, it was found that the difference of the
dielectric layers influences the resolution limit of super-RENS, and the layers with a
compressive stress show the highest resolution until 60 nm. The aperture formation
mechanism was discussed under the condition of the energy balance between the layer
internal stress and the aperture formation free-energy. The principle and the dynamic
optical nonlinearities of a new super-RENS disk using silver-oxide are
also described.
Structural Studies of Vacuum-Deposited Thin Film of Permethyloligosilanes with Phenyl End Groups
Authors: Yoshiro Ichino Yoshiro Ichino , Tetsuo Yatabe Tetsuo Yatabe , Nobutsugu Minami Nobutsugu Minami
Published: October 2002

Thin films of permethyloligosilanes with phenyl end groups, Ph(SiMe2)nPh (n = 10, 12), were prepared by vacuum deposition at various temperatures. The deposited thin films were investigated by X-ray diffractometry in terms of multilayered structures and varying incident-angle absorption spectroscopy in terms of their molecular orientations. The interlayer spacings in the multilayered structures are reasonably well explained by assuming interdigitated structures with the molecules oriented normal to the substrates. When the films were deposited onto cold substrates, another structure appeared, in which molecules are oriented parallel to the substrate. Introduction of phenyl end groups was found to reduce the domain sizes in thin films.
Characterization of Titanium Oxide Films Prepared by Liquid Phase Deposition Using Hexafluorotitanic Acid
Authors: Lee Ming-Kwei , Lei Bo-Hsiung
Published: October 2002

Using a mixture of hexafluorotitanic acid, boric acid and silicon substrate,
high-refractive-index titanium oxide films can be deposited on silicon substrates;
this results in a featureless surface. The Ti–O, Si–O and Si–O–Ti bonds were
observed by Fourier transform infrared spectroscopy, indicating that the film is a
combination of SiO2 and TiO2. The leakage current density and dielectric
constant of the deposited films were examined in this paper.
A 1.2-V Operation Power Pseudomorphic High Electron Mobility Transistor for Personal Handy Phone Handset Application
Authors: Chang Edward Yi , Lee Di-Houng , Chen Szu-Hung
Published: October 2002

A 1.2 V GaAs power pseudomorphic high electron mobility transistors (PHEMT's) for personal handy phone system (PHS) handset application was developed. The power PHEMT has a dual delta doped AlGaAs/InGaAs/GaAs based structure with compact device layout. The 6.72 mm device exhibits maximum power added efficiency (PAE) of 43.62% at 1.2 V drain bias with an output power of 22.18 dBm. Under 1.9 GHz π/4-shifted quadrature phase shift keying (QPSK) modulated PHS signal, the device shows an adjacent channel leakage power (P
adj) of -56.86 dBc at 600 kHz apart from the center frequency and a linear efficiency of 41.31%. This is the first report on the 1.2-V operation power PHEMT for PHS handset application so far.
Molecular Beam Epitaxial Growth of Hexagonal CdSe and ZnCdSe on Cubic GaAs(111)B Substrates
Authors: Matsumura Nobuo , Ueda Jun , Saraie Junji
Published: October 2002

Conditions for obtaining hexagonal wurtzite CdSe and ZnCdSe epilayers were investigated by molecular beam epitaxy on cubic zincblende GaAs(111)B substrates. The wurtzite CdSe epilayers tended to grow under high VI/II beam-pressure ratios and low growth temperatures. The growing axis of the ZnCdSe epilayer grown at 280°C was tilting toward the Zn effusion cell position. The tilting and the crystallinity were improved by increasing the growth temperature from 280 to 320°C. The wurtzite-inclusion rates in the ZnCdSe epilayers increased with increasing Cd composition of the epilayers and exceeded 90% at the Cd composition of 0.57. The wurtzite-inclusion rates in the Zn0.8Cd0.2Se epilayers increased with increasing VI/II beam-pressure ratios and saturated at above the VI/II pressure ratio of approximately 6.
Pulsed Electron-Beam Diode with Active Plasma Cathode
Authors: Nakagawa Yoshiro , Kodera Ryusuke
Published: October 2002

Multipoint surface discharge on a polyethylene surface supplied cathode plasma to a pulsed electron beam source operated by a low-power (P
M=10.9 J) Marx generator at a low maximum voltage of 170 kV. The intensity of the surface discharge on the active cathode, that is, the operating characteristics of the electron beam diode, was controlled by an external resistor. A 121A pulsed electron beam with a peak energy of 93 keV and a pulse width of about 1 µs was generated, and the stability of the diode operation was very good. A high-output electron beam power P
B of 5.02 J (46% of P
M) and a high electron beam diode input power P
D of 9.74 J (89% of P
M) were achieved. To develop a higher-efficiency electron beam source, the energy flow from the energy stored in the Marx generator to the output electron beam power in the geometry of the electron beam injection into a gas cell was clarified.
Damage-Free and Hydrogen-Free Nitridation of Silicon Substrate by Nitrogen Radical Source
Authors: Fujisaki Yoshihisa , Ishiwara Hiroshi
Published: October 2002

New damage free nitridation process of a silicon substrate is proposed with the use of a nitrogen radical source. The process also realized the hydrogen-free film that ensured high resistance against high temperature oxidation processes. It was also found that thicker than 3 nm films could be synthesized at room temperature using atomic N radicals. The metal insulator semiconductor (MIS) diode composed of radical nitride Si3N4 shows no hysteresis in capacitance voltage characteristics even after the annealing at 950°C. It was demonstrated that the application of Si3N4 films to the most advanced field effect transistors became much easier than the conventional processes with the use of radical nitridation.
Dielectric Constant of Boron Nitride Films Synthesized by Plasma-Assisted Chemical Vapor Deposition
Authors: Sugino Takashi , Tai Tomoyoshi
Published: October 2002

Polycrystalline boron nitride (BN) films are synthesized by plasma-assisted chemical vapor deposition using BCl3 and N2 as source gases. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared absorption (FTIR) measurements are carried out to characterize the BN films. Capacitance–voltage (C–V) characteristics are measured for Au/BN/p-Si samples. The dielectric constant is estimated from the capacitance in the accumulation region and the film thickness. A dielectric constant as low as 2.2 is achieved for the BN film. It is found that incorporation of carbon atoms into BN films is effective in reducing the dielectric constant.
Dislocation-Free Czochralski Si Crystal Growth without Dash Necking Using a Heavily B and Ge Codoped Si Seed
Authors: Huang Xinming , Taishi Toshinori , Yonenaga Ichiro , Hoshikawa Keigo
Published: October 2002

Dislocation-free Czochralski Si crystals were grown from undoped Si melt without Dash necking using heavily B and Ge codoped Si seeds 15×15 mm2 in cross-section. The concentration of B in codoped Si seeds was 2×1019 atoms/cm3 and that of Ge 8×1019 atoms/cm3. Dislocations due to thermal shock did not form in heavily B-doped seeds nor due to lattice misfit in grown crystals despite the very different B concentration in seeds and grown crystals. This indicates that B and Ge codoping adjusted the lattice constant of Si seeds to that of grown crystals.
Material Design of Half-Metallic Zinc-Blende CrAs and the Synthesis by Molecular-Beam Epitaxy
Authors: Akinaga Hiro , Manago Takashi , Shirai Masafumi
Published: October 2002

A new class of half-metallic ferromagnets has been found in the zinc-blende crystal structure. The previously nonexistent zinc-blende CrAs thin films have been synthesized on GaAs (001) substrates by molecular-beam epitaxy, and show a ferromagnetic behavior at room temperature. The zinc-blende CrAs has been designed by ab initio calculations based on the local spin-density approximation, and the calculation predicts the highly spin-polarized electronic band structure.
Si-Fullerene Compounds Produced by Controlling Spatial Structure of an Arc-Discharge Plasma
Authors: Hirata Takamichi , Motegi Noriyuki , Hatakeyama Rikizo , Oku Takeo , Mieno Tetsu , Sato Naoyuki , Mase Hiroshi , Niwano Michio , Miyamoto Nobuo , Sato Noriyoshi
Published: October 2002

Silicon-fullerene compounds are produced in a modified fullerene generator, where a direct-current (DC) or a radio-frequency (RF) discharge is superimposed in the periphery region of an arc-discharge plasma. The soot mass analysis gives spectrum peaks corresponding to silicon-endohedral fullerenes Si@C
n
(n=74, 86, etc.). The soot structure analyses with X-ray diffraction (XRD) and high-resolution electron microscopy (HREM) demonstrate that there exist nanoparticles with the fullerene size, which are considered to be Si@C
n
, and carbon nanocapsules filled with SiC.
Epitaxial Growth of Pure 30Si Layers on a Natural Si(100) Substrate Using Enriched 30SiH4
Authors: Nakabayashi Yukio , Segawa Toru , Osman Hirman I. , Saito Kazumasa , Matsumoto Satoru , Murota Junichi , Wada Kazumi , Abe Takao
Published: October 2002

A 30Si epitaxial layer was grown by gas source molecular beam epitaxy (GS-MBE) using isotopically enriched 30SiH4. Its crystallinity and flatness were confirmed by reflection high-energy electron diffraction (RHEED). The concentrations of Si isotopes in the 30Si layer were measured with secondary ion mass spectrometry (SIMS). The isotope composition is 28Si:29Si:30Si=0.05:0.07:99.88. No carbon or oxygen peaks were observed at the interface between the 30Si epitaxial layer and the substrate.
Growth of AlInN on (111)GaAs Substrates
Authors: Guo Qixin , Okada Akira , Kidera Hiroshige , Nishio Mitsuhiro , Ogawa Hiroshi
Published: October 2002

Ternary AlInN is grown on (111)GaAs substrates by reactive radio-frequency magnetron sputtering using aluminum and indium targets in an ambient of argon and nitrogen. Highly c-axis-oriented films with a wurtzite structure are obtained. It is revealed that the composition of AlInN layers can be controlled by changing the ratio of the sputtered area of the aluminum plate to that of the indium plate.
Blue Photoluminescence from ZnCdO Films Grown by Molecular Beam Epitaxy
Authors: Keiichiro Sakurai Keiichiro Sakurai , Takeshi Kubo Takeshi Kubo , Daisuke Kajita Daisuke Kajita , Tetsuhiro Tanabe Tetsuhiro Tanabe , Hidemi Takasu Hidemi Takasu , Shizuo Fujita Shizuo Fujita , Shigeo Fujita Shigeo Fujita
Published: October 2002

Blue luminescence from textured ZnCdO films grown by molecular beam epitaxy was observed. The properties of ZnCdO films grown at various Zn/Cd partial pressures were studied by several techniques including X-ray diffraction, fluorescence (FL) microscopy and Auger electron spectroscopy. With increasing CdO content, the properties of ZnCdO films changed sharply at specific Zn/Cd partial pressures. Some of the films grown at approximately the threshold pressures showed blue luminescence at room temperature, with large Stokes shift leaving the absorption edge in the UV region. By FL microscopy, it was observed that the blue luminescent regions were nonuniformly distributed, suggesting composition fluctuation.
Chemical Vapor Deposition Based Preparation on Porous Silica Films
Authors: Yasutaka Uchida Yasutaka Uchida , Takashi Katoh Takashi Katoh , Satoshi Sugahara Satoshi Sugahara , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Porous silica films with a low dielectric constant, k, have been prepared from the gas phase using a mixture of Si(NCO)4, N(CH3)3 and (C6H5)2Si(N(CH3)2)2. After desorption of phenyl groups chemically bonded with Si in the as-deposited film, the film showed a porosity of 48%, and k as low as 2.5. Low-field resistivity and breakdown strength were about 1015 Ω·cm, and 1.3 MV/cm due to pinhales, respectively.
Refractive Index of CsB3O5 Grown by Top-Seeded Solution Growth
Authors: Kagebayashi Yoshio , Morimoto Yukihiro , Miyazawa Shintaro , Sasaki Takatomo
Published: October 2002

CsB3O5 (CBO) crystals were grown by the top-seeded solution growth (TSSG) technique from a slightly Cs2O-enriched melt. The measured refractive indices of the CBO crystals disagreed with the previously reported values by a factor of 10-2. The reason for the disagreement was speculated to be the difference in Cs concentration in the CBO crystal and/or impurity concentration. Single-term Sellmeier's equations for TSSG-CBO were used for measuring refractive indices. The phase-matching angles of harmonic and sum-frequency generations of Nd:YLiF4 lasers were calculated based on single-term Sellmeier's equations, and the phase-matching angle of second-harmonic generation was verified experimentally.
Heat-Resistant Polyarylates for Waveguide-Type Device Application
Authors: Sugihara Okihiro , Tomiki Masahiro , Fujimura Hisashi , Egami Chikara , Okamoto Naomichi , Akizuki Takamasa , Shirai Hiromasa
Published: October 2002

Polyarylates (PARs) with high glass transition temperature (T
g) of over 200°C are newly synthesized and used for waveguide-type device application. Thermal and optical properties of PARs are investigated, and results indicate that PARs show high thermal stability as well as high optical transparency in the visible region. High-resolution relief gratings on PAR thin films are fabricated by a direct electron-beam (EB) writing technique together with thermal development. Using a reactive-ion-etching (RIE) technique, the waveguide channel ridge was fabricated.
Correlation between Ferroelectricity and Grain Structures of Face-to-Face Annealed Strontium Bismuth Tantalate Thin Films
Authors: Aizawa Koji , Ishiwara Hiroshi
Published: October 2002

The correlation between ferroelectricity and grain structures of sol-gel-derived strontium bismuth tantalate (SBT) thin films prepared by face-to-face annealing were investigated. In face-to-face annealing, an SBT film is directly placed, with the film side down, on an other SBT film during the crystallization process. The remanent polarization value of a face-to-face-annealed SBT film was 21 µC/cm2 at an annealing temperature of 750°C, while it was 7 µC/cm2 in the film prepared without face-to-face annealing. It was found from cross-sectional transmission electron microscope images that the SBT films prepared by face-to-face annealing were composed of dense, and of uniform layers corresponding to the annealing cycles, while the films prepared without face-to-face annealing were composed of randomly packed irregular grains. These results suggest that the improvement in ferroelectricity of the face-to-face annealed SBT films is due to the formation of dense, uniform layers.
Hyperthermal O3 Beam Produced by Laser Ablation of Solid-Ozone Film
Authors: Nishiguchi Tetsuya , Morikawa Yoshiki , Miyamoto Masaharu , Nonaka Hidehiko , Ichimura Shingo
Published: October 2002

In order to obtain a highly concentrated hyperthermal ozone beam for more effective Si oxidation, we performed laser ablation of solid-ozone. A KrF pulse laser was irradiated onto solidified ozone on a sapphire substrate cooled to 30 to 60 K using a cryocooler. A mixture of ozone, molecular oxygen and atomic oxygen was detected using a time-of-flight method through a quadrupole mass filter. The velocity distribution of ablated ozone molecules was almost the same as the distribution at thermal equilibrium. An ozone beam with a fitted temperature of 2500 K and maximum translational energy of 3 eV was obtained under optimum laser conditions.
Jitter Raising Mechanisms for Compact Disk (CD)-Rewritable at Quadruple CD Velocity
Authors: Chang Yem-Yeu , Chou Lih-Hsin
Published: October 2002

A disk designed for compact disk (CD) 2X is employed to test its performance at CD 4X. The erasability at CD 4X is poorer than that at CD 2X. A sharp increase in jitter after overwriting for CD 4X was observed as a result of the existence of two different amorphous mark shapes. One of them is of normal shape and the other is extended with a tail in the trailing part. For overwriting more than 50 times, only one type of amorphous mark with tiny sharp tail was observed. This singular amorphous mark shape gives rise to a decrease in jitter. For much higher overwriting cycles, the jitter will increase with the amount of pinholes present.
Photoinduced Resistivity Change Due to Spin-Disorder in a Manganite Film
Authors: Liu Xiao Jun , Moritomo Yutaka , Nakamura Arao , Asano Hidefumi
Published: October 2002

Photoinduced resistivity change (ΔR/R) in a La0.6Sr0.4MnO3 film has been investigated with variation of the excitation energy E
exc (1.88–3.20 eV) and temperature (290–400 K). The magnitude of the photoinduced resistivity change steeply decreases with increasing temperature beyond T
c∼315 K. In addition, we have found that the photoinduced signal is enhanced when the down-spin e
g carriers are excited. Based on these experimental findings, we have ascribed the positive ΔR/R signal to the photoinduced spin disorder in the ferromagnetic metallic (FM) state.
Stranski-Krastanov Growth of InAs Quantum Dots with Narrow Size Distribution
Authors: Koichi Yamaguchi Koichi Yamaguchi , Kunihiko Yujobo Kunihiko Yujobo , Toshiyuki Kaizu Toshiyuki Kaizu
Published: October 2002

Coherently strained InAs quantum dots (QDs) with narrow inhomogeneous broadening were grown by molecular beam epitaxy (MBE) using the Stranski-Krastanov (SK) growth mode. The increase in the InAs dot size and decrease in the dot density were induced by surface migration enhancement due to the low arsenic pressure below 6×10-7 Torr. In addition, the low arsenic pressure and the low growth rate produced the self size-limiting effect, which was attributed to the inhibition of indium incorporation. As a result, the narrowest photoluminescence (PL) linewidth of 18.6 meV (14 K) was successfully obtained from the single InAs/GaAs QD layer.
Effects of Backgate Voltage on Electrical Characteristics of Poly-Si Thin Film Transistors Fabricated on Stainless-Steel Substrate
Authors: Serikawa Tadashi , Omata Fujio
Published: October 2002

High mobility p-channel polycrystalline Si thin film transistors (poly-Si TFTs) are fabricated on flexible stainless-steel substrates coated with 500-nm-thick SiO2 and 50-nm-thick SiN films. The electrical characteristics of mobility, threshold voltage and subthreshold slope are first measured as a function of backgate voltage V
BG of from -26 V to +20 V applied on stainless-steel substrate. Mobilities show small dependence on V
BG. Threshold voltages, however, have dependence of decreasing with increasing V
BG. Subthreshold slopes also show concave-shaped dependence on V
BG. The results indicate that electrical characteristics of poly-Si TFTs are controlled by simply applying voltages to the substrate. Thus, application of backgate voltage are very important for design advanced poly-Si TFT integrated circuits and to secure stable operation of the circuits.
Dark Current in Quantum Dot Infrared Photodetectors
Authors: Victor Ryzhii Victor Ryzhii , Victor Pipa Victor Pipa , Irina Khmyrova Irina Khmyrova , Vladimir Mitin Vladimir Mitin , Magnus Willander Magnus Willander
Published: October 2002

We present the results of a new analytical model for the analysis of the dark current in realistic quantum dot infrared photodetectors (QDIPs). This model includes the effect of the space charge formed by electrons captured in QDs and donors, the self-consistent electric potential in the QDIP active region, the activation character of the electron capture and its limitation by the Pauli principle, the thermionic electron emission from QDs and thermionic injection of electrons from the emitter contact into the QDIP active region, and the existence of the punctures between QDs. The developed model yields the dark current as a function of the QDIP structural parameters, applied voltage, and temperature. It explains some features of the dark current characteristics observed experimentally.
Highly Uniform 1.5 µm Wavelength Deeply Etched Semiconductor/Benzocyclobutene Distributed Bragg Reflector Lasers
Authors: Madhan Raj Mothi , Jörg Wiedmann Jörg Wiedmann , Yoshikazu Saka Yoshikazu Saka , Koji Ebihara Koji Ebihara , Shigehisa Arai Shigehisa Arai
Published: October 2002

The lasing performance of deeply etched distributed Bragg reflector (DBR) lasers was improved to a threshold current as low as 7.2 mA and a differential quantum efficiency as high as 50% with high uniformity. The reflectivity of the 15-DBR reflector was estimated to be as high as 95% from the threshold current dependence on the active region length. A preliminary test under room-temperature CW operation showed stable operation for a duration in excess of 4000 hours.
The Effect of Metal Chloride Fluxes on the Properties of Phosphor Particles in Spray Pyrolysis
Authors: Kang Yun Chan , Park Hee Dong , Park Seung Bin
Published: October 2002

The effect of metal chloride fluxes with different melting temperatures on the properties of Y2O3:Eu phosphor particles was investigated in spray pyrolysis. A flux of low melting temperature helps to produce particles of higher photoluminescence (PL) intensity. The maximum PL intensity of particles was obtained from the solution with a mixture of KCl and LiCl. The intensity was 142% of that of particles prepared from solution without flux. The increase of brightness of particles prepared from flux solution was not resulted from the improvement of crystallinity, morphology, and degree of activation. The higher PL intensity of particles prepared from solution with metal chloride flux than that of particles prepared from solution without flux was caused by the change of surface characteristics of particles. Therefore, metal chloride flux material with low melting temperature was more effective than that with high melting temperature.
Retarded Diffusion of Phosphorus in Silicon-on-Insulator Structures
Authors: Uchida Hideo , Ieki Yasushi , Ichimura Masaya , Arai Eisuke
Published: October 2002

Phosphorus diffusion profiles in bonding silicon-on-insulator
(SOI) structures are compared with those in bulk Si. Phosphorus
diffusion is carried out at 900 and 1000°C, using a
spin-on-glass source which enables achievement of a high surface
concentration near solid solubility. The diffusion methods consist
of both predeposition diffusion in N2 ambient and drive-in
diffusion in N2 or O2 ambients following a short time
predeposition. Results show that predeposition diffusion in the SOI
structures is retarded at 900°C as compared with that in bulk
Si, while it is not at 1000°C. The diffusion retardation
appears more clearly for the SOI structure with a thinner active
layer and longer diffusion time. In the drive-in diffusion at
900°C, retardation occurs in O2 ambient, but not in
N2 ambient. These results are explained by considering the
extinction of excess interstitial Si at the Si/SiO2 interface
in the SOI structure.
Essential Change in Crystal Qualities of GaN Films by Controlling Lattice Polarity in Molecular Beam Epitaxy
Authors: Ide Xu-Qiang Shen , Shimizu Sung-Hwan Cho , Hara Shiro , Okumura Hajime , Sonoda Saki , Shimizu Saburo
Published: October 2002

GaN heteroepitaxial growth on sapphire (0001) substrates was carried out by radio-frequency plasma-assisted
molecular beam epitaxy (rf-MBE). A Ga-polarity growth was achieved by using an AlN high-temperature buffer layer.
The epilayer polarity was characterized directly by coaxial impact collision ion scattering spectra (CAICISS). It was
found that the properties of the GaN films showing Ga-face polarity, including their structural and electrical properties,
were dramatically improved compared to those of films with N-face polarity. This important conclusion is considered
to be a breakthrough in the realization of high-quality III-nitride
films by MBE for device applications.
A Novel Plasma-Based Copper Dry Etching Method
Authors: Kuo Yue , Lee Sangheon
Published: October 2002

A new copper dry etching method has been discovered and studied. The process is based on an unique HCl plasma-copper reaction that forms a solution soluble copper chloride compound. The physical (e.g., morphology, profile, volume expansion, and anisotropy) and chemical (e.g., reaction mechanism) aspects of the solid-state copper chloride growth mechanism have been delineated. This new process is applicable to the copper interconnection technology for advanced microelectronic and optoelectronic devices and circuits.
Thin-Film Transistors with Polycrystalline Silicon Films Prepared by Two-Step Rapid Thermal Annealing
Authors: Cheng Huang-Chung , Huang Chun-Yao , Wang Fang-Shing , Lin Kuen-Hsien , Tarntair Fu-Gow
Published: October 2002

A novel two-step rapid thermal annealing (RTA) process has been
developed to significantly reduce the crystallization time for the
solid-phase crystallization (SPC) of amorphous silicon films. In
comparison with the conventional SPC processes, it not only keeps a
low thermal budget but also achieves a larger poly-Si film grain
size than that obtained by one-step RTA, and even as large as that
obtained by conventional furnace annealing (CFA). Furthermore,
poly-Si thin-film transistors fabricated by such a novel annealing
scheme possess electrical characteristics superior to those obtained
by one-step RTA and comparable to those obtained by long-time CFA.
High-Quality GaN on AlN Multiple Intermediate Layer with Migration Enhanced Epitaxy by RF-Molecular Beam Epitaxy
Authors: Sugihara Daisuke , Kikuchi Akihiko , Kusakabe Kazuhide , Nakamura Shinichi , Toyoura Yousuke , Yamada Takayuki , Kishino Katsumi
Published: October 2002

High-speed GaN growth of 1.0 µm/h with migration enhanced epitaxy (MEE)
by molecular beam epitaxy using rf-plasma nitrogen (RF-MBE) was demonstrated. The
electron mobility of MEE-GaN was 362 cm2/V·s for the electron density of
1.7×1017 cm-3 at room temperature. The threading dislocation
density of MEE-GaN was estimated to be 1.0–3.0×1010 cm-2
based on the cross-sectional transmission electron microscope (TEM) image. The
remarkable improvement of electrical properties was obtained by the introduction of a
high-temperature (750°C) grown AlN/GaN multiple intermediate layer (AlN-MIL).
The cross-sectional TEM image showed that threading dislocations were bent or
terminated at the AlN-MIL. The highest room temperature mobility of
668 cm2/V·s was obtained at the electron density of
9.5×1016 cm-3. The low-temperature peak mobility was
2340 cm2/V·s at 90 K.
Hardness of Bulk Single-Crystal Gallium Nitride at High Temperatures
Authors: Yonenaga Ichiro , Hoshi Tetsuya , Usui Akira
Published: October 2002

The hardness of single-crystal gallium nitride at elevated temperatures is
measured and compared with that of other semiconductors. A Vickers indentation
method was used to determine the hardness under an applied load of 0.5 N in the
temperature range 20–1200°C. The average hardness was measured as 10.8 GPa
at room temperature, which is comparable to that of Si. At elevated temperatures, GaN
shows higher hardness than Si and GaAs. A high mechanical stability for
GaN is deduced.
Characterization of Polarity of Wurtzite GaN Film Grown by Molecular Beam Epitaxy Using NH3
Authors: Sonoda Saki , Shimizu Saburo , Shen Xu-Qiang , Hara Shiro , Okumura Hajime
Published: October 2002

Effects of the initial nitridation of a sapphire(0001) substrate by NH3 on
the polarity of GaN{0001} film have been investigated by coaxial impact collision ion
scattering spectroscopy. The polarity of ammonia-molecular beam epitaxial (MBE) film
grown on the substrate nitrided using NH3 is assigned as (0001). The effect of the
initial nitridation of the substrate by NH3 is found to be contrary to that by
nitrogen plasma, where the GaN film grown on the nitrided substrate shows the polarity
of (0001). The polarity of GaN film grown by rf plasma-assisted MBE on the
substrate which is nitrided using NH3 is also (0001). These findings suggest the
possibility of polarity control of the grown GaN film by choosing the N source for
initial nitridation of the substrate.
Selective Deposition of Electroless Plating Films Using the Difference between the Functional Groups of Self-Assembled Monolayers
Authors: Ishida Masaya , Kasuga Mayumi , Kaneko Takeo , Shimoda Tatsuya
Published: October 2002

In this paper, we present that the two kinds of self-assembled monolayers
(SAMs) can be patterned on a Si substrate by the UV irradiation or scanning probe
microscope (SPM) lithography technique. Furthermore, we can obtain selective
patterning of electroless Ni films by using the difference between the functional
groups of SAMs and the submicron-size electroless pattern fabricated by SPM
lithography. The mechanism of selective deposition is discussed referring to the
X-ray photoemission spectroscopy (XPS) results.
Oriented and Non-Oriented HfO2–Y2O3 Films on Amorphous Quartz Glass Substrates Prepared by Sol-Gel Processes
Authors: Nishide Toshikazu , Honda Shinji , Matsuura Masaharu , Ito Yoshiaki , Takase Tsugiko
Published: October 2002

Transparent HfO2–8 mol%Y2O3 films were prepared on
amorphous quartz glass substrates by sol-gel processes using HfCl4 and
YCl3·6H2O as starting materials. Oriented and
non-oriented films were obtained by varying the firing conditions. The oriented films
were formed by maintaining the firing temperature in the electric furnace above
490°C. Depth profiles of the crystals in the films and transmission electron
microscopy of the films revealed that oriented crystals grew near the surface of the
films.
Preparation, Optical Properties and Yellow Electroluminescence of Water-Soluble Poly(p-phenylene vinylene)
Authors: Akihiko Fujii Akihiko Fujii , Tooru Sonoda Tooru Sonoda , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Novel carboxy-substituted poly(p-phenylene vinylene), poly(1,4-(2-(5-carboxypentyloxy)-5-methoxyphenylene)vinylene) (CPMOPPV) has been synthesized. The obtained polymer is soluble in organic solvents, such as acetone and ethanol, and the sodium salt of CPMOPPV is soluble even in water. The optical properties of CPMOPPV, such as optical absorption and photoluminescence have been studied, and yellow-electroluminescence devices have been fabricated. The electronic energy structure of CPMOPPV has been determined by optical and electrochemical measurements. CPMOPPV has been demonstrated to be one of the candidate polyanions for fabrication of the organic multilayer structure by the self-assembly technique.
Ultra-High Vacuum Optical Second Harmonic Microscope
Authors: Sonoda Yasuyuki , Mizutani Goro , Sano Haruyuki , Ushioda Sukekatsu , Sekiya Takao , Kurita Susumu
Published: October 2002

We have developed an optical second harmonic (SH) microscope for surface
analysis in ultra-high vacuum. We have combined a commercial long-distance
microscope, intensified charge coupled device (CCD) camera, optical filters, a cavity
dumped mode-locked Nd3+:YAG laser, and an ultra-high vacuum chamber for
constructing the SH microscope. The spatial resolution of the SH microscope is
estimated to be around 6 µm. We have observed a nonuniform density distribution
of CO adsorption on a Pt(110) surface.
Direct Nanomolding of Semiconductor Single Crystals
Authors: Masuda Hideki , Yasui Kenji , Yanagishita Takashi , Nakao Masashi , Tamamura Toshiaki , Nishio Kazuyuki
Published: October 2002

An ordered array of concaves of nanometer-scale dimensions was fabricated by a direct molding process on an InP single crystal using a SiC master mold. The obtained array of concaves could be applied for the preparation of an ordered textured surface of InP by a post-etching treatment. The treatment in hydrofluoric acid (HF) solution generated a highly ordered and textured surface composed of uniform pyramidal or triangular pits. The mold could be used repeatedly, and this method enables simple maskless patterning of semiconductor single crystals.
Electrical Characteristics of Ultra-Thin Oxynitride Gate Dielectric Prepared by Reoxidation of Thermal Nitride in D2O
Authors: Yeo Hyungshin Kwon , Hyunsang Hwang Hyunsang Hwang
Published: October 2002

The electrical and reliability characteristics of ultra-thin oxynitride
gate dielectric prepared by oxidation of thermal nitride in D2O
ambient were investigated. Compared with H2O reoxidation, D2O
reoxidation exhibit less hole trapping, larger charge-to-breakdown and
significant reduction of interface state generation under the electrical
stress. The improvement of electrical and reliability characteristics
can be explained by the deuterium incorporation. The new oxynitride gate
dielectric prepared by D2O reoxidation provides a good promise for
future ultra large scaled integration (ULSI) device applications.
Reduced Polarization Sensitivity of Multimode Interference 1×4 Demultiplexers
Authors: Cho Mu-Hee , Hyun Kyung-Sook , Yoo Byueng-Su , Kim Yeong Sik
Published: October 2002

We have fabricated a multimode interference (MMI) 1×4 demultiplexer
with reduced polarization sensitivity in InP/InGaAsP. Channel-to-channel crosstalk
of the MMI demultiplexer for the transverse electric (TE) and transverse magnetic (TM)
modes are <-15 dB and <-16 dB, respectively. The wavelength shifts between
the TE and TM modes are less than 0.3 nm.