bluuebunny/crossref_metadata_2025 huggingface dataset:
Self Consistent Model For InP Selective Regrowth by Hydride Vapour Phase Epitaxy
Authors: Gopalakrishnan Nammalvar , Messmer Egbert Rodriguez , Lourdudoss Sebastian
Published: October 2002

The surface diffusion mechanism of InP selective regrowth around [110] and
[110] directional etched InP mesas by hydride vapour phase epitaxy (HVPE) is
investigated. A model has been proposed on the basis that the excess area growth
in the immediate vicinity of mesas takes place due to an accumulation of materials
fed by surface diffusion from the top of the mesa. The surface diffusion length and
surface diffusion coefficient along [110] direction (i.e. case of [110] directional
mesa) and [110] direction (i.e. case of [110] directional mesa) are estimated for
the first time. It is observed that the surface diffusion length and surface diffusion
coefficient towards [110] direction are about three and eight times higher than
those towards [110] direction, respectively. The anisotropic growth behaviour in
these directions is explained due to these differences in the surface diffusion lengths.
The validity of the model is justified by a self consistent calculation.
Effect of Growth Conditions on Electrical Properties of Si-Doped In0.52Al0.48As Grown by Metalorganic Vapor Phase Epitaxy
Authors: Goto Shu , Ueda Takashi , Ohshima Tomoyuki , Kakinuma Hiroaki
Published: October 2002

A systematic study of the electrical properties of Si-doped In0.52Al0.48As grown under various
metalorganic vapor phase epitaxy (MOVPE) conditions such as V/III ratio and growth temperature
is carried out. It is demonstrated that either high V/III ratios
(≥64) or high growth temperatures (≥720°C) are
necessary for obtaining good InAlAs electrical properties. For a small
V/III ratio (=32)
and low growth temperatures (≤700°C), a large discrepancy is found in Hall carrier concentration
(n
Hall), ionized impurity concentration (N
C – V), and Si concentration (N
Si); N
C – V>N
Si>n
Hall; which
can be explained by the dual formation of donor and acceptor deep levels. SIMS results suggest that
carbon and oxygen impurities are not candidates for these deep levels, and other origins such as
intrinsic defects, which are closely related to growth conditions, are applicable.
GaAs and InP Nanohole Arrays Fabricated by Reactive Beam Etching Using Highly Ordered Alumina Membranes
Authors: Nakao Masashi , Oku Satoshi , Tamamura Toshiaki , Yasui Kenshi , Masuda Hideki
Published: October 2002

Highly ordered anodic porous alumina was used as a mask for a reactive beam etching
(RBE) to transform the nanochannel pattern into III-V semiconductors. The alumina mask
showed high tolerance to RBE using a Br2/N2 mixed gas system. GaAs and InP nanohole
arrays with a high aspect ratio and with diameter uniformity of 2%, which was as good as that of
the alumina mask, were obtained.
Mechanism of Carrier Accumulation at the Hetero Interface between InSb and GaAs
Authors: Tanaka Takeshi , Washima Mineo , Sakaguchi Harunori
Published: October 2002

Various surface orientations of GaAs were used as substrates for InSb epitaxial growth,
and the dependence of the interface carrier density on substrate surface indexes was discovered.
The interface carrier density increased in proportion to the dangling bond density at the hetero
epitaxial interface, and carrier accumulation was significantly suppressed using a (111) substrate
which had the least dangling bond density among all the surface indexes of a zinc-blende
structure. A carrier accumulation model based on the estimated band diagrams at the hetero
junction was proposed and well explained these experimental results.
X-Ray Photoelectron Spectroscopy and Ultrahigh Vacuum Contactless Capacitance-Voltage Characterization of Novel Oxide-Free InP Passivation Process Using a Silicon Surface Quantum Well
Authors: Takahashi Hiroshi , Hashizume Tamotsu , Hasegawa Hideki
Published: October 2002

In order to understand and optimize a novel oxide-free InP passivation process using a silicon surface quantum well, a detailed in situ X-ray photoelectron spectroscopy (XPS) and ultrahigh vacuum (UHV) contactless capacitance-voltage (C-V) study of the interface was carried out. Calculation of quantum levels in the silicon quantum well was performed on the basis of the band lineup of the strained Si3N4/Si/InP interface and the result indicated that the interface should become free of gap states when the silicon layer thickness is below 5 Å. Experimentally, such a delicate Si3N4/Si/InP structure was realized by partial nitridation of a molecular beam epitaxially (MBE) grown pseudomorphic silicon layer using an electron cyclotron resonance (ECR) N2 plasma. The progress of nitridation was investigated in detail by angle-resolved XPS. A newly developed UHV contactless C-V method realized in situ characterization of surface electronic properties of InP at each processing step for passivation. It was found that the interface state density decreased substantially into the 1010 cm-2 eV-1 range by optimizing the nitridation process of the silicon layer. It was concluded that both the surface bond termination and state removal by quantum confinement are responsible for the N
SS reduction.
Characterization of InGaAs Phosphidized by a Plasma Process
Authors: Miyazaki Takashi , Sugino Takashi , Matsuda Koichiro , Shirafuji Junji
Published: October 2002

Phosphidization of InGaAs is attempted using a remote phosphine plasma. Au
Schottky junctions are formed on the phosphidized and Ar-plasma-treated InGaAs
layers and their electrical properties are characterized. Traps are investigated by
isothermal capacitance transient spectroscopy measurements. Two electron traps
are detected and designated as E1 and E2. The energy levels of the E1 and E2 traps
are 0.35 eV and 0.48 eV below the conduction band edge, respectively. In the case
where InGaAs is treated with PH3-added Ar plasma, a significant reduction in the
densities of both E1 and E2 traps occurs in comparison with those of Ar-plasma-treated InGaAs. It is found that phosphorus atoms are effective in suppressing the
generation of electron traps in InGaAs.
High-Resolution Scanning Electron Microscopy Observation of Electrochemical Etching in the Formation of Gate Grooves for InP-Based Modulation-Doped Field-Effect Transistors
Authors: Xu Dong , Enoki Takatomo , Suemitsu Tetsuya , Ishii Yasunobu
Published: October 2002

We show that during the wet-chemical formation of gate grooves for InAlAs/InGaAs-heterojunction-based modulation-doped field-effect transistors, the etching rates of InGaAs and InAlAs can be significantly modified by the exposure of the non-alloyed ohmic electrodes to citric-acid-based etchant. The presence of a Ni surface metal enhances the recess etching rate to a degree that is much higher than that in its absence. The presence of a Pt surface metal, however, causes this originally non-selective etchant to preferentially etch InGaAs over InAlAs. This selective etching behavior is attributed to the excess oxidation of InAlAs induced by the high electrode potential of Pt via an electrochemical effect. This study reveals the important impacts of electrochemical etching on the fabrication of gate recess grooves.
Fabrication and Characterization of InP Heterojunction Bipolar Transistors with Emitter Edges Parallel to [001] and [010] Crystal Orientations
Authors: Matine Noureddine , Dvorak Martin W. , Pelouard Jean-Luc , Pardo Fabrice , Bolognesi Colombo R.
Published: October 2002

We present a study of fully-self aligned InP-based heterojunction bipolar transistors (HBTs) with the emitter edges oriented parallel to the [0,0,1] and [0,1,0] crystal orientations. A technology based on vertical and lateral wet etching of InP was developed to fabricate emitter-up and collector-up InP/InGaAs HBTs with reduced parasitic resistances and capacitances. For emitter-up HBTs, the undercut distance between the base contact and the emitter active area was <0.3 µm in all directions, and high frequency performance of f
T=105 GHz and f
MAX=82 GHz were obtained for a 4×12 µm2 emitter area. For collector-up metal HBTs (MHBTs), emitter widths as small as 0.5 µm were formed by lateral wet etching with a relative area fluctuation less than 10%, and high frequency performance of f
T=40 GHz and f
MAX=160 GHz were obtained for a 0.5×52 µm2 emitter area.
Improved High-Temperature and High-Power Characteristics of 1.3-µm Spot-Size Converter Integrated All-Selective Metalorganic Vapor Phase Epitaxy Grown Planar Buried Heterostructure Laser Diodes by Newly Introduced Multiple-Stripe Recombination Layers
Authors: Furushima Yuji , Yamazaki Hiroyuki , Kudo Koji , Sakata Yasutaka , Okunuki Yuichiro , Sasaki Yoshihiro , Sasaki Tatsuya
Published: October 2002

Multiple-stripe planar buried heterostructure (MS-PBH) was newly developed to improve the high-temperature and high-power characteristics of spot-size converter integrated all-selective metalorganic vapor phase epitaxy (MOVPE) grown planar buried heterostructure laser diodes (SSC-ASM-PBH LDs). Recombination-layer stripes were simultaneously grown with the active layer and thickness-tapered waveguide by narrow-stripe selective MOVPE, and inserted in the current-blocking layers. The effect of recombination-layer-stripe insertion was investigated both theoretically and experimentally. The leakage current suppressed by the inserted recombination-layer stripes resulted in improved high-temperature and high-power characteristics. A maximum output power of 47 mW at 85°C, a high characteristics temperature T
0 value of 69 K (25°C–85°C), and a small slope-efficiency degradation of 1.1 dB (25°C–85°C) were obtained while maintaining excellent coupling characteristics to a flat-ended single-mode fiber due to its narrow beam divergence.
InGaAsP/InP Multi-Mode Interference Photonic Switches for Monolithic Photonic Integrated Circuits
Authors: Nagai Shuichi , Morishima Goh , Yagi Mikito , Utaka Katsuyuki
Published: October 2002

InGaAsP/InP semiconductor photonic switches using multi-mode
interference (MIPS) are proposed for monolithic photonic integrated
circuits. Changing the refractive indices of index-modulated regions
located in the center of a multi-mode waveguide, controls its
switching functions.
It is predicted from calculations by an FD-TD (finite difference
time domain) method that these devices can operate in various kinds
of output schemes with typical device dimensions of about 8 µm width
and 540 µm length.
1×2 InGaAsP/InP MIPS's with a high-mesa structure
have been fabricated, and fundamental switching characteristics were
measured.
At the preliminary stage, switching was observed at 20 mA
current injection with about 37% extinction ratio.
Switching
efficiency and cross talk of the MIPS can be improved by optimizing
the device dimensions and structure.
The flexibility of setting the index-modulated regions suggests
versatile operation of the MIPS, such as a photonic space division
switch, a variable power splitter, or as an optical modulator.
Electrooptical Properties in a Composite System Consisting of Two Nematic and a Cholesteric Liquid Crystal
Authors: Hwang Jenn Chiu , Liang Shi Chang , Liang Kung Heng
Published: October 2002

The electrooptical properties of a liquid crystal (LC) composite
exhibiting an induced smectic phase formed by mixing two nematic LCs and
one cholesteric LC
has been studied. The ternary composite exhibited smectic A, cholesteric
and blue phases. A unique circular texture was observed in the
cholesteric-smectic phase transition region. In the absence of electric
field, the ternary system exhibited highly transparent and opaque states
in the smectic phase and cholesteric phase, respectively. Reversible and
bistable transparent-opaque change was successfully realized in the
cholesteric state of the ternary composite upon application of high- and
low-voltage DC electric fields.
Deposition of (100) and (110) Textured Diamond Films on Aluminum Nitride Ceramics via Hot Filament Chemical Vapor Deposition
Authors: Shang Naigui , Fang Rongchuan , Liao Yuan , Cui Jingbiao
Published: October 2002

Textured (100) and (110) diamond films were successfully grown on aluminum
nitride ceramics at different substrate temperatures via hot filament chemical vapor
deposition (HFCVD). The surface morphology and the crystallographic properties of the
two textured films were characterized by scanning electron microscopy and X-ray
diffraction. The highest ratios of the diffraction intensity, I
(400)/I
(111) (about 5.8) of (100)
textured films and I
(220)/I
(111) (about 2.2) of (110) textured films, are greatly larger than that
of randomly oriented diamond films (0.08 and 0.25). The optimized conditions of textured
films on AlN substrates were obtained. The experimental results showed that the substrate
temperature played an important role in the texture types of diamond films. The growth
mechanism of the two texture films is discussed in detail.
Change in Chemical Bonding States in Electron-Irradiated Graphite
Authors: Muto Shunsuke , Takeuchi Minoru , Tanabe Tetsuo , Kurata Hiroki , Hojou Kiichi
Published: October 2002

The damage process in electron-irradiated graphite was investigated by electron energy-loss
spectroscopy (EELS). An analysis of the extended energy-loss fine structure
(EXELFS) revealed that new components with slightly different interatomic distances grew
with irradiation time in the first-nearest neighbor coordination shell. In addition, the energy-loss
near edge structure (ELNES) exhibited features characteristic of higher fullerenes. The
consistency of these results can be explained by the formation of non-sixfold atomic rings
by electron irradiation, similar to fullerenes.
Selective Area Growth by Metal Organic Vapor Phase Epitaxy and Atomic Layer Epitaxy Using Ga2O3 as a Novel Mask Layer
Authors: Hirose Shingo , Yoshida Akihiro , Yamaura Masaaki , Hara Kazuhiko , Munekata Hiro
Published: October 2002

A novel technique is proposed for advanced microstructure formation using Ga2O3 as a
new mask material. Ga2O3 layers were prepared by RF sputtering with Ga2O3 powder target
and patterned using photolithography. Scanning electron microscope (SEM) and
Photoluminescence (PL) measurement findings indicate that reasonably high-quality single
crystalline GaAs layers could be successfully grown selectively on the unmasked region by
metal organic vapor phase epitaxy (MOVPE) and atomic layer epitaxy (ALE). The
GaAs/AlGaAs quantum structure was also fabricated by selective area MOVPE, however, at
this stage, polycrystalline AlGaAs layers formed on the mask region after the mask removal
and the regrowth of AlGaAs overlayers. The key factor in this microstructure fabrication
process is the sensitive dependence of Ga oxide layers against the reactor pressure under H2
exposure.
A New Super-Resolution Film Applicable to Read-Only and Rewritable Optical Disks
Authors: Shintani Toshimichi , Terao Motoyasu , Yamamoto Hiroki , Naito Takashi
Published: October 2002

A new super-resolution material for optical disks is proposed which contains cobalt oxide
as a main component and shows a refractive index change upon irradiation of a laser
beam. This new material is different from the ones already proposed for super-resolution
in that it is durable against high-power laser irradiation and thus is applicable to
rewritable optical disks as well as read-only (ROM) disks. This paper reports
fundamental properties of this material, C/N improvement of ROM and phase-change
disks with this material, and its durability against continuous many-time readout. The
potential of this technique is discussed.
High-Speed Recording Performance of Metal Azo Dye Containing Digital Video Disc-Recordable Discs
Authors: Suzuki Yuki , Okamoto Yuuko , Kurose Yutaka , Maeda Shuuichi
Published: October 2002

We have studied the high-speed performance at speeds of 3.5 m/s–14.0 m/s of digital
video disc recordable (DVD-R) discs which contain metal azo dyes. Good recording
sensitivity and good mark jitter with carrier-to-noise ratio (C/N) > 50 dB at mark lengths
of less than 0.40 µm were demonstrated at over 10 m/s due to the high recording
responses of the dyes. Furthermore, by introducing the write strategy with pulse trains,
the sensitivity difference between mark lengths could be completely eliminated and
excellent recording with a jitter value of 8% level has been achieved at 7.0 m/s with a
minimum mark length of around 0.4 µm.
New Digital Versatile Disc Recordable (DVD-R) with Metal Thin Film and Organic Film on Polycarbonate
Authors: Min Kyung Sun , Huh Young Jae , Shim Hong Ku
Published: October 2002

A new digital versatile disc recordable (DVD-R), called a metal polymer
deformation (MPD) DVD-R, which has a thin metal film between the polycarbonate
(PC) substrate and dye layer, was fabricated and its recording properties were
evaluated. The relationship between deformation shape on the recorded area and
recording characteristics was studied. The light stability of this disc was
compared with that of conventional DVD-R. The thin metal layer of the MPD DVD-R
improves the recording sensitivity, the modulated amplitude, and the light
stability, and widens the window of the dye selection criteria for the DVD-R.
Compositional Dependence of Optical Constants and Microstructures of GeSbTe Thin Films for Compact-Disc-Rewritable (CD-RW) Readable with Conventional CD-ROM Drives
Authors: Kato Naohiko , Takeda Yasuhiko , Fukano Tatsuo , Motohiro Tomoyoshi , Kawai Shouichi , Kuno Hironari
Published: October 2002

We studied the dependence of optical constants and microstructures of
(GeTe)
x
(Sb2Te3)1-x
films on composition to determine the optimal composition of phase
change recording materials. The maximal differences in optical constants between
crystalline and amorphous phases and the minimal crystalline grain sizes of the films were
obtained at Ge39Sb10Te51. Using Ge39Sb10Te51 as a recording layer and TiO2 and SiO2 as
interference layers, a compact disc rewritable (CD-RW) with 65% reflectivity and 60%
modulation was obtained.
Magnetic Domain Pinning in Lithographically Patterned Amorphous Magnetic Layer
Authors: Wu Jong-Ching , Huang Ying-Wen , Chen Bing-Mau , Wu Te-ho , Shieh Han-PingD.
Published: October 2002

Artificial pinning sites have been fabricated for the magnetic domain pinning in perpendicular
anisotropy magneto-optical (MO) thin film media. The pinning sites were radial hole array
made by patterning a layer of radial gold grid on the silicon nitride (SiN) coated silicon (Si)
substrate using a standard electron beam lithography. Various magnetization and
demagnetization procedures were performed to investigate the magnetic domain pinning
behavior. A polar Kerr microscope was used in situ to monitor the magnetic wall motion and a
magnetic force microscope was employed to scan the magnetic domain structures. Magnetic
domains were found to be pinned inside the hole array and resembled to the geometric shape of
the holes. The coercivity in the patterned MO layer is much higher than in the unpatterned MO
layer. Moreover, the coercivity in the larger pinning sites area is higher than in the smaller
pinning sites area.
Analysis and Comparison of Polysilicon Contacted Ultra-Shallow Junction p+- and n+-poly Gate p-Channel Metal-Oxide-Semiconductor Field-Effect Transistors by Two-Dimensional Simulation
Authors: Liou Wan-Rone , Liao Fan-Shen
Published: October 2002

An alternative process for ultra-shallow junction p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) is proposed in this paper. The doping of the source/drain is accomplished by diffusion from a heavily doped overlayer of polycrystalline silicon. Bothp+- andn+-poly gate devices with this diffusion technology are compared and evaluated for a channel length of 0.12 µm. We model transistors obtained by industrial integrated circuit technology on the basis of data provided by the chip manufacture. Results of simulation reveal that extremely shallow 0.05 µm junctions can be achieved, and laterally uniform delineated junctions are observed. As in the traditional process, the problems of punchthrough current and drain induced barrier lowering are effectively suppressed by the proposedp+-poly gate device. The superior subthreshold behavior makes the device suitable for applications in low-voltage and low-power circuit.
Optically Detected Far-Infrared Magnetoabsorption in InGaAs
Authors: Hiroyasu Nakata Hiroyasu Nakata , Nobuhiro Shimizu Nobuhiro Shimizu , Tyuzi Ohyama Tyuzi Ohyama , Youichi Nonogaki Youichi Nonogaki , Yasufumi Fujiwara Yasufumi Fujiwara , Yoshikazu Takeda Yoshikazu Takeda
Published: October 2002

InGaAs epitaxial layers lattice-matched to InP substrates are studied by photoluminescence measurements modulated by far-infrared radiation under the
condition of cyclotron resonance or impurity cyclotron resonance. Based on the experimental results, the ionization energy of shallow donors is estimated to be 2.3 meV, which is lower than the value of 3.0 meV obtained from the effective mass approximation. In order to explain the difference between the two values, we propose a model of the existence of a Ga-rich region in samples. In addition to electron cyclotron resonance, hole cyclotron resonance is observed. The effective masses of electron and light hole are estimated to be 0.041m0 and 0.051m0, respectively.
High-Quality InGaAs Layers Grown on (411)A-Oriented InP Substrates by Molecular Beam Epitaxy
Authors: andSatoshi Hiyamizu Takahiro Kitada
Published: October 2002

High-quality In
x
Ga1-x
As layers (0.505 ≤x ≤0.545)
were grown on (411)A-oriented InP substrates
by molecular beam epitaxy (MBE).
High-resolution X-ray diffraction (HRXRD) measurements
of the (411)A In
x
Ga1-x
As layers
showed no relaxation of lattice mismatch,
and residual strain components observed in the (411)A InGaAs layers
were in good agreement with
calculated results based on
the constrained pseudomorphic layer model
on high index substrates
proposed by Yang et al. [Appl. Phys. Lett. 65 (1994) 2789].
Photoluminescence (PL) linewidth of
the (411)A InGaAs layer with In content (x) of 0.505
was 1.9 meV at 12 K,
which is less than half
that (4.0 meV) of an InGaAs layer simultaneously grown on
a (100) InP substrate,
and almost the same as the optimum value (1.2–3.0 meV)
reported for InGaAs layers grown on (100) InP substrates.
These results indicate that
high-quality InGaAs layers can be easily obtained
by MBE growth on (411)A InP substrates.
Comparison between Fermi-Dirac and Boltzmann Methods for Band-bending Calculations of Si/CaF2/Au Hot Electron Emitter
Authors: Zhang Bingyang , Ikeda Yoshihiro , Kikegawa KazuhitoFuruya
Published: October 2002

Fermic-Dirac statistics is used to calculate the band bending at the semiconductor
surface of n-Si/CaF2/Au hot electron emitter. Due to the need for the application of a relatively
large positive voltage and an ultra-thin insulator layer in the scanning hot electron
microscopy (SHEM) experiment for this emitter, the Fermi level can cross the conduction
band bottom at the semiconductor surface. A partial region of the space charge at the
semiconductor surface will be in the state of degeneracy and the Boltzmann statistics will be
invalid even for the non-degenerate substrate. The calculated results of band bending from
the Boltzmann approximation and Fermi-Dirac statistics are compared for different doping
densities and different insulator thicknesses. At the same time, the effect of band bending
obtained by the two methods on the transmission probability of electrons through the
insulator has also been discussed.
A Piezoresistive Silicon Accelerometer Using Porous Silicon Micromachining and Flip-Chip Bonding
Authors: Sim Jun-Hwan , Lee Jong-Hyun
Published: October 2002

A piezoresistive silicon accelerometer using porous silicon micromachining and flip-chip bonding is
presented. This micromachining technique, which provides the benefits of surface micromachining
along with the capabilities of bulk micromachining, was applied for fabricating the micromechanical
structure of an accelerometer. The flip-chip bonding technology with numerous advantages, such as a
low inductance and resistance, excellent high-frequency behavior, and high-density interconnection,
compared to conventional interconnection methods, was also proposed. This bonding technology is
thought to be promising for implementing electrical interconnections between the sensor chip and the
substrate.
Direct Bonding between Quaternary Compound Semiconductor and Garnet Crystals for Integrated Optical Isolator
Authors: Yokoi Hideki , Mizumoto Tetsuya , Shimizu Masafumi , Futakuchi Naoki , Kaida Noriaki , Nakano Yoshiaki
Published: October 2002

An integrated optical isolator employing a nonreciprocal phase shift is very
attractive because it does not need phase matching. We have investigated a novel
configuration of the integrated optical isolator, employing the nonreciprocal phase shift,
in which the magnetooptic waveguide has a magnetic garnet/GaInAsP/InP structure.
The wafer direct bonding technique is necessary to realize this structure. The direct
bonding between quaternary III–V compound semiconductors and garnet crystals was
experimentally studied. The bonding was achieved by chemical treatment and subsequent
heat treatment at temperatures ranging from 110 to 330°C. Cross-sectional scanning
electron microscope (SEM) images indicated that there were no gaps between the two
wafers in contact.
Exchange Couplings in Ni–Fe/Mn–Ir/Fe–Mn Multilayers
Authors: Nakatani Ryoichi , Hoshiya Hiroyuki , Hoshino Katsumi , Sugita Yutaka
Published: October 2002

Exchange couplings between antiferromagnetic layers and
magnetic layers have been investigated in Hf/Ni–20 at.%Fe/Mn–22 at.%Ir/Fe–40 at.%Mn/Ni–20 at.%Fe/Hf/Si multilayers. The
Mn–Ir antiferromagnetic layers formed on the Fe–Mn
antiferromagnetic layers have γ-Mn crystal structures from
the bottom surfaces to the top surfaces. The structures
cause relatively high exchange bias fields applied to the
Ni–Fe layers neighboring the Mn–Ir layers.
Preparation, Characterization, and Photo-induced Liquid Crystal Alignment of Polyimide and Poly(vinyl cinnamate) Blend Alignment Layer
Authors: Kim Hee-Tak , Park Jung-Ki
Published: October 2002

In this paper, the preparation, characterization, and
photo-induced liquid crystal (LC) alignment of a polyimide (PI)
derived from cyclobutane
dianhydride and
2,2-bis(4-aminophenoxyphenyl)propane, and a poly(vinyl cinnamate)
(PVCi) blend alignment layer are reported. Microscopic and thermal
analyses revealed the miscibility of the two components in the thin
layers.
The occurrence of photo-dimerization and the development of structural
dichroism in the blend layers were confirmed from ultra-violet (UV)
spectroscopic investigations. The photo-dimerization reaction of the
cinnamate was not significantly influenced by the addition of PI into
PVCi.
The blend alignment layers provided uniform LC alignment, and better
thermal stability of LC alignment compared to the pure PVCi alignment
layer.
The increase of the thermal imidization temperature was found to enhance the thermal stability of LC alignment, which indicates that the increase of T
g by introducing PI to PVCi is responsible for the improvement of the thermal stability of LC alignment.
Growth Kinetics of Silicon Carbide Chemical Vapor Deposition from Methyltrichlorosilane
Authors: Tsutomu Kaneko Tsutomu Kaneko , Hayato Sone Hayato Sone , Nobuaki Miyakawa Nobuaki Miyakawa , Mitihiro Naka Mitihiro Naka
Published: October 2002

The epitaxial chemical vapor deposition of SiC on (100) and (111) Si substrates has
been conducted in a cold wall furnace from methyltrichlorosilane (MTS) as the single
source material. In the temperature range from 1100°C to 1350°C,
both surface-reaction-limited growth and diffusion-limited growth have been
observed. The activation energy for growth was decreased using a two-step
process route in which an intermediate layer was deposited by controlling only
the partial pressure of the MTS.
Investigation of Substrate-dependent Characteristics of SnO2 Thin Films with Hall Effect, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy and Atomic Force Microscopy Measurements
Authors: Byeongdeok Yea Byeongdeok Yea , Hajime Sasaki Hajime Sasaki , Tomoyuki Osaki Tomoyuki Osaki , Kazunori Sugahara Kazunori Sugahara , Ryosuke Konishi Ryosuke Konishi
Published: October 2002

SnO2 thin films of 100 nm in thickness were prepared on glass and alumina
substrates with targets-facing type sputtering apparatus to investigate the
substrate-dependent characteristics of the films. The sensitivity of the films
is measured in flammable gas atmosphere (hydrogen, butane and methane, 5000 ppm),
and it revealed that the SnO2 films on alumina substrates showed better
sensitivity for all introduced gases than the films on glass substrates.
Hall effect, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS)
and atomic force microscopy (AFM) measurements were performed to clarify
the difference of the sensitivity, and it is concluded as follows:
1) The variation of carrier concentration of the films on alumina substrates is
larger than those on glass substrates when they are exposed to flammable gases.
2) The structure of the films on alumina substrates is similar to that of SnO2 powder.
3) The film on an alumina substrate contains more oxygen impurities than that on a glass substrate,
which can be considered to cause the large variation of carrier concentration.
4) Surface area of the films on alumina substrates is wider than that
of the films on glass substrates.
An Application of Monte Carlo Method on Simulating Optical Aberration of Automatic Inspection System
Authors: Chen Li , Suzuki Masafumi , Yoshimura Noboru
Published: October 2002

In an automatic inspection system, the improvement in image quality has a close relationship with aberration of the detecting lens. A new analysis method for aberration using the Monte Carlo method is presented in this paper. The theoretical analysis and simulation results reveal the following: The aberration is related to the relative ray height in the entrance pupil. In the presence of aberration, there exist some symmetric distortions in the margin of the pattern, and if the two lenses have equal but opposite ray aberration, these aberrations can exactly cancel each other. This research not only supplies a new way for analyzing the aberration in lenses but also points out an available method for analyzing the automatic inspection system.
Improved Electron-Beam/Deep-Ultraviolet Intralevel Mix-and-Match Lithography with 100 nm Resolution
Authors: Magoshi Shunko , Niiyama Hiromi , Sato Shinji , Kato Yoshimitsu , Watanabe Yumi , Shibata Tohru , Ito Masamitsu , Ando Atsushi , Nakasugi Tetsuro , Sugihara Kazuyoshi , Okumura Katsuya
Published: October 2002

We have developed a novel electron-beam (e-beam)/deep-ultraviolet (DUV) intralevel mix-and-match (ILM&M) lithography as a production-viable technology. The
main feature of the ILM&M lithography is its use of a DUV biased exposure method for
increased throughput and a combination of a variably shaped e-beam/character projection
writer with a step-and-repeat DUV scanning system for accurate intralevel butting
between e-beam and DUV patterns. It was demonstrated that the throughput of e-beam
writing in the ILM&M lithography could reach about three times that of e-beam
lithography, and that an intralevel butting accuracy of less than 50 nm could be achieved.
The proposed ILM&M has been successfully applied to the development and early
production of leading edge devices at our laboratory.
Merged DRAM with Logic/Analog (MDLA) Technology for Single-Chip Solution
Authors: Yoon Jong Shik , Yu Sunil , Lee Hyae Ryoung , Kwon Chul-Soon , Kim Dong Woo , Kim Won Chul , Choi Chang-Sik
Published: October 2002

This paper describes a process integration of Merged DRAM (dynamic random
access memory) with Logic and Analog (MDLA) using high performance 0.35 µm CMOS
technology for the implementation of “System on a Chip”. DRAM whose cell size was 2.1 µm2 and analog cores were embedded in 0.35 µm logic chip without sacrifice of
transistor performance of logic circuitry. The obtained values of I
dsaturation of
NMOS/PMOS transistors were about 530 and 250 µA/µm at 3.3 V, respectively. Dual gate
oxide process was developed to support 5 V operation as well as 3.3 V
operation. The key process feature of this study was that the aluminum alloy layer
was used as a bit line in DRAM cells on the contrary to the employment of polycide
in the conventional DRAM technology. In this study, metal-insulator-metal (MIM)
capacitor scheme was employed for the applications in high-resolution analog cores.
The low value of voltage coefficient of capacitance as low as 10 ppm/V could be
achieved with MIM scheme.
Epitaxial Growth of Bi4Ti3O12 Thin Films on LaAlO3(012) and MgO(100) by Dipping-Pyrolysis Process
Authors: Hwang Kyu-Seog , Kim Byung-Hoon , Manabe Takaaki , Yamaguchi Iwao , Kumagai Toshiya , Mizuta Susumu
Published: October 2002

Epitaxially grown Bi4Ti3O12 films on LaAlO3(012) and
MgO(100) substrates have been prepared by the dipping-pyrolysis process using metal naphthenates. It was confirmed
that the degree of epitaxy of the films strongly depends on
the lattice misfit between the Bi4Ti3O12 film and the
substrate used; the film on LaAlO3(012), with a small
lattice-misfit value, showed a high degree of epitaxy in
comparison with the film on MgO(100).
Low-Temperature Formation of Silicon Nitride Film by Direct Nitridation Employing High-Density and Low-Energy Ion Bombardment
Authors: Saito Yuji , Sekine Katsuyuki , Hirayama Masaki , Ohmi Tadahiro
Published: October 2002

High-integrity silicon nitride films can be obtained at a temperature of 400°C using a
newly developed high-density (>1012 cm-3) plasma characterized by low ion bombardment
energies of below 7 eV. It was found for the first time that stoichiometric silicon nitride can
be formed at a temperature of 400°C by precise control of nitrogen partial pressure to
generate N2
+ in plasma. The growth rate and the electrical properties of this silicon nitride are
similar to those of thermally grown nitride. Moreover, hysteresis of the C–V curve attributed
to charge traps in the silicon nitride film disappeared with the addition of hydrogen to Ar/N2
plasma, and the leakage current of the nitride film was decreased dramatically by irradiating
in Ar/N2/H2 plasma after Ar/N2 plasma nitridation. These technologies are very promising for
fabricating feature metal substrate silicon-on-insulator (SOI) devices and silicon nitride gate
metal-insulator-semiconductor field effect transistors (MISFETs).
Influences of Impurities on Oxidation Processes of Si(100) Substrates
Authors: Ikeda Hiroya , Nakagawa Yasuyuki , Sato Kenji , Zaima Shigeaki , YukioYasuda YukioYasuda
Published: October 2002

We have investigated the influences of impurities in Si
substrates on the oxidation processes and local bonding structures of
silicon dioxide (SiO2) films on deuterium- (D-) terminated
Si(100) surfaces by high-resolution electron energy loss spectroscopy.
It is found that the oxidation processes such as the oxidation rate
and the preferential adsorption of oxygen (O) atoms on one of the two
back bonds of a surface Si atom are hardly influenced by the impurity
element and the impurity concentration. Moreover, boron (B) atoms
promote the relaxation of SiO2 films by changing the Si-O force
constant. This effect of B atoms is considered to originate from a
long-range interaction such as the Coulomb interaction.
A Novel Non-Destructive Characterization Method of Electronic Properties of Pre- and Post-Processing Silicon Surfaces Based on Ultrahigh-Vacuum Contactless Capacitance-Voltage Measurements
Authors: Yoshida Toshiyuki , Hasegawa Hideki , Sakai Takamasa
Published: October 2002

An ultrahigh-vacuum (UHV) contactless capacitance-voltage (C-V) technique was developed
and applied to various silicon (Si) wafers. The system carries out C-V measurements in a UHV
chamber from a field plate separated from the sample surface by a UHV-gap. The UHV-gap length
was shown to be accurately determined by measuring the variation of reflectance of the laser light
due to the Goos-Hächen effect. It was demonstrated that the conduction type, carrier
concentration and surface Fermi level position could be determined on the Si surface before and
after processing. Surface state distributions such as hydrogen terminated surfaces and Si surface
covered with an ultrathin insulator were successfully characterized by an in-situ and a
nondestructive fashion in UHV environments. This method seems to be very powerful for in-situ
electronic characterization of “free” and/or “processed” semiconductor surfaces.
A Fluorinated Organic-Silica Film with Extremely Low Dielectric Constant
Authors: Yasutaka Uchida Yasutaka Uchida , Kohshi Taguchi Kohshi Taguchi , Satoshi Sugahara Satoshi Sugahara , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

A fluorinated organic-silica film was prepared by quasi hydrogen-free chemical-vapor deposition. The content of methyl groups and fluorine atoms incorporated in the film were as much as 43% and 9% of that of Si. The film had good insulating characteristics with the dielectric constant, k, of as low as 2.5 even under as-prepared conditions. They were improved by vacuum annealing; k was 2.1 and
the low-field resistivity was 1016 Ωcm after annealing at
500°C. It was confirmed that the film prepared at 200°C was stable for more than 20 days in the air.
Hydrogen-Enhanced Boron Penetration in PMOS Devices during SiO2 Chemical Vapor Deposition
Authors: Aoyama Takayuki , Suzuki Kunihiro , Tada HirokoTashiro , Kataoka Yuji , Arimoto Hiroshi , Horiuchi Kei
Published: October 2002

We demonstrated that boron penetration through gate oxides is more significant in a
SiO2 chemical vapor deposition ambient than in a N2 ambient. By systematically
evaluating hydrogen concentration dependence on boron diffusivity in gate dielectrics,
we determined that enhanced boron diffusion through gate oxides was attributable to
hydrogen in the SiO2 chemical vapor deposition source gas.
Thin and Low-Resistivity Tantalum Nitride Diffusion Barrier and Giant-Grain Copper Interconnects for Advanced ULSI Metallization
Authors: Nakao Shin-ichi , Numata Masashi , Ohmi Tadahiro
Published: October 2002

The barrier performance and properties (resistivity, crystalline phase and surface
microroughness) of tantalum nitride films, as well as the relationship between grain size and
diffusivity of copper films, are reported. The resistivity and R
a roughness of Ta2N film
formed by reactive sputtering using argon and nitrogen plasma are ∼200 µΩ·cm and ∼0.35 nm, respectively. The Ta2N diffusion barrier exhibits better barrier performance than Ta4N and
bcc-Ta diffusion barriers. Giant-grain copper interconnects formed by sputtering in low-energy ion bombardment process show lower diffusivity than small-grain copper
interconnects. The barrier performance of tantalum nitride film was evaluated by electrical
measurement. An n+p junctions having 20 µm×20 µm contact holes filled with 10-nm-thick
Ta2N diffusion barriers and giant-grain copper interconnects exhibit no increase in reverse-bias current after annealing at 700°C for 30 min in argon ambient.
Formation of Size- and Position-Controlled Nanometer Size Pt Dots on GaAs and InP Substrates by Pulsed Electrochemical Deposition
Authors: Sato Taketomo , Kaneshiro Chinami , Hasegawa HiroshiOkada
Published: October 2002

Attempts were made to form regular arrays of size- and
position-controlled Pt-dots on GaAs and InP by combining an in
situ electrochemical process with the electron beam (EB)
lithography. This utilizes the precipitation of Pt nano-particles at
the initial stage of electrodeposition. First, electrochemical
conditions were optimized in the mode of self-assembled dot array
formation on unpatterned substrates. Minimum in-plane dot diameters of
22 nm and 26 nm on GaAs and InP, respectively, were obtained under
the optimal pulsed mode. Then, Pt dots were selectively formed on
patterned substrates with open circular windows formed by EB
lithography, thereby realizing dot-position control. The Pt dot was
found to have been deposited at the center of each open window, and
the in-plane diameter of the dot could be controlled by the number,
width and period of the pulse-waveform applied to substrates. A
minimum diameter of 20 nm was realized in windows with a diameter of
100 nm, using a single pulse. Current-voltage (I-V)
measurements using an atomic force microscopy (AFM) system with a
conductive probe indicated that each Pt dot/n-GaAs contact possessed a
high Schottky barrier height of about 1 eV.
Measurement of Energetic and Lateral Distribution of Interface State Density in Fully-Depleted Silicon on Insulator Metal-Oxide-Semiconductor Field-Effect Transistors
Authors: Duyet Tran Ngoc , Ishikuro Hiroki , Shi Yi , Takamiya Makoto , Saraya Takuya , Hiramoto Toshiro
Published: October 2002

A new modification of the charge pumping (CP) technique
based on the effect of reverse pulse bias on
suppression of the geometric component is proposed
in order to accurately determine the energetic and lateral distribution
of interface state density (D
it)
in fully-depleted silicon on insulator
metal-oxide-semiconductor field-effect transistors (FD SOI MOSFETs).
A comparison of the conventional CP techniques
with the proposed method is also presented.
It is demonstrated that using the proposed method,
the precise estimation of the energetic and lateral distribution
of D
it can be simply obtained
without interference from the
geometry-dependent effect which often leads to the great difficulties in data
interpretation in the conventional CP methods.
Effects of Initial Surface Reconstruction on Silicon Interface Control Layer Based Passivation of (001) GaAs Surfaces Studied in an Ultrahigh-Vacuum Multichamber System
Authors: Mutoh Morimichi , Tsurumi Naohiro , HidekiHasegawa HidekiHasegawa
Published: October 2002

In order to understand and to further optimize the silicon interface control layer
(Si ICL)-based passivation process for GaAs, the effects of the initial surface
reconstruction of GaAs on the microscopic surface structures of the Si ICL and on the
macroscopic electronic properties are studied in situ, using an ultrahigh-vacuum (UHV)
multi-chamber system. (2×4) and c(4×4) GaAs surfaces were prepared by molecular beam
epitaxy (MBE). Surface structures and compositions were studied by UHV scanning
tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Macroscopic
electronic properties of the passivated surfaces were investigated by XPS band bending
measurements, UHV contactless capacitance-voltage (C-V) measurements and UHV
photoluminescence (PL) methods.
The Si layer grown on the initially reconstructed c(4×4) surface was found to be
more ordered and flatter than that grown on the initially reconstructed (2×4) surface. This
difference showed a strong correlation with the macroscopic electronic properties after the
Si ICL-based passivation process measured by XPS, UHV contactless C-V and PL
techniques. The results indicate the importance of the two-dimensional
order on the Si-deposited surfaces for successful passivation.
Carrier Mobility Dependence of Electron Spin Relaxation in GaAs Quantum Wells
Authors: Ryota Terauchi Ryota Terauchi , Yuzo Ohno Yuzo Ohno , Taro Adachi Taro Adachi , Arao Sato Arao Sato , Fumihiro Matsukura Fumihiro Matsukura , Atsushi Tackeuchi Atsushi Tackeuchi , Hideo Ohno Hideo Ohno
Published: October 2002

We have investigated the electron mobility (µ) dependence and the electron quantized energy dependence of the electron spin relaxation time (τs) in n-type and undoped GaAs/AlGaAs multiple quantum wells at room temperature. τs ∝µ-1 obtained from the experimental results is consistent with the theoretical prediction based on the D'yakonov-Perel' theory.
Interplay of Excitonic Radiative Recombination and Ionization in Photocurrent Spectra of Thick Barrier GaAs/AlAs Multiple Quantum Wells
Authors: Kawasaki Koji , Imazawa Masaaki , Kawashima ToshioImanishi , Fujiwara Kenzo , Hosoda Makoto , Tominaga Koji
Published: October 2002

We have studied photocurrent (PC) spectroscopic features of a
relatively thick barrier GaAs/AlAs multiple quantum well p-i-n diode
at 18 K. It is found that the PC spectra do not reflect the
photoabsorption spectral lineshape under the low field condition and
show negative PC peaks at the exciton resonance wavelengths where the
absorption coefficient is maximum. These PC dips are qualitatively
explained by considering the distribution of photogenerated carriers
and competition between the carrier transport and recombination. A
tunneling model calculation is carried out to successfully explain the
PC spectral features as well as the field dependence of PC intensity
by taking into account the photogenerated carrier distribution and the
excitonic absorption lineshape variations with the field.
Optoelectronic Flexible-Function Logic Gate Using Monostable-Bistable Transition of Serially Connected Resonant Tunneling Transistors
Authors: Yutaka Ohno Yutaka Ohno , Shigeru Kishimoto Shigeru Kishimoto , Koichi Maezawa Koichi Maezawa , Takashi Mizutani Takashi Mizutani , Tomoyuki Akeyoshi Tomoyuki Akeyoshi
Published: October 2002

A novel optoelectronic resonant tunneling logic gate, OE MOBILE, is proposed and its basic logic functions such as NOT, NOR, NAND, OR, and AND are confirmed for optical inputs.
The fundamental idea is to use optical inputs to determine the logic level of the gate which consists of two serially connected resonant tunneling transistors (RTTs) with a p+/n-junction gate.
The OE MOBILE is operated by oscillating bias voltage to employ monostable-bistable transition.
At the time when the transition occurs, the optical inputs are applied by illuminating the RTTs to control their peak currents and consequently to determine the output logic levels.
The power of an optical input for logic operations is as small as 5 µW owing to the operation based on monostable-bistable transition.
It should be pointed out that the functions of an OE MOBILE can be changed between NOR and NAND by changing the control terminal voltage.
Device Properties of Homo- and Heteroepitaxial ZnSe-Based Laser Diodes
Authors: Helmut Wenisch Helmut Wenisch , Martin Behringer Martin Behringer , Michael Fehrer Michael Fehrer , Matthias Klude Matthias Klude , Andreas Isemann Andreas Isemann , Kazuhiro Ohkawa Kazuhiro Ohkawa , Detlef Hommel Detlef Hommel
Published: October 2002

The characteristics of ZnSe-based laser diodes
grown on GaAs and ZnSe substrates are discussed. There is no
significant difference observed in the dynamic behavior and in the operating
voltages between the two cases. The degradation mechanism is similar with the developing
of dark line defects and a 1/t-like decrease in light intensity at
constant current for t →∞. The width of the dark
line defects is in homoepitaxy almost constant in time, although
their number is higher. This difference is also reflected in the
lifetimes of our devices during lasing, which is in heteroepitaxy
three minutes and about one second in homoepitaxy, for both in cw
operation at room temperature.