bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of Boron Diffusion in High-Dose BF2 Implanted Silicon
Authors: Uematsu Masashi
Published: October 2002

We have simulated the transient enhanced diffusion (TED) of boron (B) after
amorphizing BF2 ion implantation in silicon. A unified simulation is done based on
the models for B diffusion, for TED by self-interstitial clusters, for B clustering and B
precipitation, and for end-of-range (EOR) defects. The simulation overestimates the
diffusion using the normal values for the efficiency of EOR defects as a source of
self-interstitials. The simulation well reproduces the experimental profiles when the
efficiency is reduced so that the defects maintain self-interstitial concentration at
thermal equilibrium values. This reduction is attributable to the presence of fluorine at
EOR defect sites, which may prevent the release of self-interstitials. In addition, the
second peak near the amorphous/crystalline (a/c) interface observed in experimental
profiles is reproduced, and the peak is attributed to B precipitates.
Improvement of Electrical Properties of Pulsed Laser Crystallized Silicon Films by Oxygen Plasma Treatment
Authors: Yoshiyuki Tsunoda Yoshiyuki Tsunoda , Toshiyuki Sameshima Toshiyuki Sameshima , Seiichiro Higashi Seiichiro Higashi
Published: October 2002

Changes in the electrical properties of pulsed laser crystallized silicon films with oxygen plasma treatment were investigated. 50-nm-thick silicon films doped with 7.4 ×1017 cm-3 phosphorus atoms crystallized by a 308-nm-XeCl excimer laser at an energy density of 400 mJ/cm2 were treated by 30-W-RF plasma of oxygen gas at 130 Pa at 250°C. The electrical conductivity markedly increased from 6.9 ×10-5 S/cm (as crystallized) to 10 S/cm by heat treatment for 40 min. Theoretical analysis of the electrical conductivity revealed that the potential barrier height at grain boundaries decreased from 0.32 eV (as crystallized) to almost zero, and that carrier mobility increased from 15 cm2/Vs (as crystallized) to 170 cm2/Vs.
The Study of the Origin of the Anomalously Large Thermoelectric Power of Si/Ge Superlattice Thin Film
Authors: Hiroko Uchino Hiroko Uchino , Yoichi Okamoto Yoichi Okamoto , Toshio Kawahara Toshio Kawahara , Jun Morimoto Jun Morimoto
Published: October 2002

We present the experimental framework for the origin of the anomalously large thermoelectric power for Si and Au-doped Ge superlattice thin film. The thermoelectric power of the sample still remains anomalously large even though the superlattice structure begins to collapse. An amorphous Ge thin film displays large thermoelectric power. The crystallized samples have almost the same thermoelectric power as that of conventional SiGe bulk samples. The main cause of this anomalously large thermoelectric power of Si/Ge superlattice thin films is amorphous Ge layer.
InAlAs/Pseudomorphic InGaAs/InP High Electron Mobility Transistor with Doped InAs/AlAs Superlattice
Authors: Kohara Teruaki , Hoshino Koichi , Taguchi Takashi
Published: October 2002

We have demonstrated a novel indium phosphide high electron mobility transistor
(HEMT) which has prevented sheet carrier density degradation. The fabricated structure
replaces n-In0.52Al0.48As with an n-InAs/n-AlAs superlattice (doped
InAs/AlAs superlattice; DIAS), preventing carrier density degradation of the n-type
doped carrier supply layer on HEMT. DIAS requires a two-dimensionally grown
seven-period superlattice each period of which has two monolayers of InAs and two
monolayers of AlAs. The fabricated HEMT exhibits improved prevention of sheet carrier
density degradation compared with the conventional HEMT with an
n-In0.52Al0.48As carrier supply layer in the case of 300–450°C
annealing and a 125°C bias temperature (BT) test.
Surface States of Hydrogen-terminated Si(111) by Metastable Atom Electron Spectroscopy and Angle-resolved Ultraviolet Photoelectron Spectroscopy
Authors: Yasufuku Hideyuki , Meguro Kazuyuki , Akatsuka Shin-ichiro , Setoyama Hiroyuki , Kera Satoshi , Azuma Yasushi , Okudaira Koji K. , Hasegawa Shinji , Harada Yoshiya , Ueno Nobuo
Published: October 2002

The surface electronic states of hydrogen-terminated Si(111)
[H–Si(111)-(1×1)] were studied by metastable atom electron spectroscopy
(MAES) and angle-resolved ultraviolet photoelectron spectroscopy (ARUPS), coupled
with an intensity analysis used for organic systems. The surface states of
H–Si(111)-(1×1) originated from Si–H bonds were selectively observed by
MAES which can excite electrons distributed at the outermost surface. Furthermore,
the prominent ARUPS peak with very small dispersion at around 10 eV binding energy
from the vacuum level was confirmed to originate from a nondispersive Si–H σ
state by quantitative analysis of the photoelectron angular distribution using a simple
computation model used for organic thin films.
Phase Sensitive Pump-Probe Spectroscopy Using a Michelson-Type Interferometer
Authors: Takao Fuji Takao Fuji , Takuya Yoda Takuya Yoda , Toshiaki Hattori Toshiaki Hattori , Hiroki Nakatsuka Hiroki Nakatsuka
Published: October 2002

Time-resolved phase sensitive pump-probe spectroscopy using a Michelson-type interferometer has been carried out. In this experiment, we obtain information on the time-resolved amplitude and phase of probe pulses by measuring cross-correlations between probe pulses and reference pulses. This method was demonstrated in an experiment on dye molecules, hexamethylindotricarbocyanine iodide, in ethylene glycol at room temperature. The experimental results indicated the time evolution of the phase and the increase in peak velocity of the probe pulse. These phenomena can be explained by phase velocity change and group velocity change due to the pump pulse. A simulation based on a two-level Bloch model for the dye molecules reproduced the experimental results quite well.
Investigation of Transient Reverse Currents in X-Ray Detector Pin Diodes by Discharge Current Transient Spectroscopy
Authors: Hideharu Matsuura Hideharu Matsuura , Kazushige Segawa Kazushige Segawa
Published: October 2002

Transient reverse currents flow in X-ray detector diodes when a high reverse bias (operating voltage) is suddenly applied from 0 V, which leads to problems in the X-ray measurements. Discharge current transient spectroscopy (DCTS) was applied to determine the densities, energy levels and capture cross sections of traps related to the transient reverse currents in the diodes. DCTS analysis revealed one type of trap with E
C-0.54 eV in our silicon pin diodes, where E
C is the energy level at the bottom of the conduction band.
Room-Temperature Heteroepitaxial Growth of NiO Thin Films using Pulsed Laser Deposition
Authors: Tachiki Minoru , Hosomi Takeshi , Kobayashi Takeshi
Published: October 2002

Room-temperature growth of NiO thin films using the pulsed laser deposition
(PLD) technique was investigated. Epitaxial growth of NiO thin films on (100)MgO
substrates was not obtained when we simply placed a shadow mask between the
substrate and target (eclipse PLD method), but was obtained when we used the
conventional PLD method under the optimum ambient pressure condition. However, by
applying a magnetic field from the substrate side during growth, NiO epitaxy was
achieved even for the eclipse PLD method. This is due to the enhanced ionization and
energization of flying species by the magnetic field application.
Ion-Induced Secondary Electron Emission Coefficient (γ) of Bulk-MgO Single Crystals
Authors: Kim Dae-Il , Lim Jae-Yong , Kim Young-Guon , Ko Jae-Jun , Lee Choon-Woo , Cho Guang-Sup , Choi Eun-Ha
Published: October 2002

The ion induced secondary electron emission coefficient γ of bulk-MgO single crystal has been measured by the
γ-focused ion beam system. It is found that the bulk-MgO single crystal with (111) orientation has the highest γ from 0.08 up to 0.21, and the γ values are in the order of the crystallinities, (111) > (200) > (220) for operating Ne+ ions ranging from 50 eV to 300 eV in this experiment. These results are consistent with our previous reports for MgO protective layers with respective orientations of (111), (200), and (220).
High-Density Current Injection to Magnetically Confined Plasmas with a Miniature Plasma Source
Authors: Motomi Iida Motomi Iida , Sadao Masamune Sadao Masamune , Hiroshi Oshiyama Hiroshi Oshiyama
Published: October 2002

Influences of high-density current injection with a miniature plasma source on a reversed-field pinch (RFP) have been studied in the Separatrix Test Experiment-2 (STE-2) device. The current injector has successfully produced a unidirectional field-aligned electron beam. No deterioration or slight improvement of the RFP discharge was observed with injection of poloidal current of up to 1 kA. The deepening of the local edge toroidal magnetic field reversal has been observed in the vicinity of the injection port. The global change in the current profile and the stabilization ofm=1 tearing modes will require current injection at multiple toroidal locations with a higher bias voltage. However, the gas throughput from the injector is too high, hindering the addition of more injectors in the STE-2 device. Global current profile control experiments with multiple miniature plasma sources are expected in larger devices.
Drag of a Laser Trapped Fine Particle in a Microregion
Authors: Masafumi Miwa Masafumi Miwa , Saulius Juodkazis Saulius Juodkazis , Hiroaki Misawa Hiroaki Misawa
Published: October 2002

To observe hydrodynamics in microregions, we applied laser scanning manipulation to measure the drag acting on a fine glass bead moving in mineral oil sandwiched between two glass plates (the thickness of the oil layer was a 33 and 64 µm). We measured the maximum velocity, V
M, of a laser trapped bead at which the bead was released. This allowed us to quantitatively determine the drag, the drag coefficient, C
D, and the Reynolds number, R, of the particle in the microregion of a viscous fluid. As a result, the minimum C
D
R was obtained midway between the two glass plates, and the C
D
R increased closer to the walls. Also, the distribution of C
D
R was in good agreement with the values calculated using the equation for wall effect in macroregions (over 0.1 mm).
Molecular Dynamics Simulation of Hydrogen Absorbing Palladium: Turnover of Hydrogen Absorption Heat into Palladium
Authors: Daigo Fukushi Daigo Fukushi , Sotoji Hiragi Sotoji Hiragi , Takuya Honda Takuya Honda
Published: October 2002

Molecular dynamics simulations were carried out for hydrogen absorption by palladium in various atomic ratios to identify the reason why hydrogen absorption heat changes from exothermic to endothermic at a high atomic ratio. Classical two-body interactions were used as interatomic potentials for these simulations in order to simplify the calculation. Pd–Pd and Pd–H interatomic potentials were determined empirically by fitting the calculated physical properties of PdHx's with observed values at an atomic ratio, and the H–H potential was given by a screened Coulomb potential. Calculated molar volumes and absorption enthalpies were consistent with observed data for a wide range of atomic ratios. These results show that the simple approach was sufficient to evaluate the absorption heat of PdHx. Analyses of crystal structure and the averaged H–H coordination number indicate that the change of the absorption heat from exothermic endothermic was not caused by a structure change, but by H–H repulsion.
Crystal Originated Particle Induced Isolation Failure in Czochralski Silicon Wafers
Authors: Park Jea-Gun , Lee Gon-Sub , Kwack Kae-Dal , Park Jung-Min
Published: October 2002

The presence of crystal originated particle (COP) on the 64 Mbyte dynamic random access memory (DRAM) device isolation region causes the current path between neighboring transistors, resulting in COP induced isolation failure. The probability of the COP induced isolation failure occurrence depends on the COP size; i.e., larger COP size leads to higher probability of failure. In addition, failure strongly depends on the process condition applied to the isolation structure, for example, the nitride film thickness; i.e., thicker nitride film results in a less probability of failure. Furthermore, failure also depends on the isolation structure itself; i.e., higher probability of the COP induced isolation failure follows local oxidation of silicon (LOCOS) > polysilicon space LOCOS (PSL) > selective polysilicon oxidation (SEPOX).
Reduction of Base Resistance and Increase in Cutoff Frequency of Si Bipolar Transistor Using Rapid Vapor-Phase Doping
Authors: Kiyota Yukihiro , Kikuchi Toshiyuki , Washio Katsuyoshi , Inada Taroh
Published: October 2002

The shallow intrinsic base region of a double poly-Si
self-aligned bipolar transistor was
formed by rapid vapor-phase doping (RVD) in order to increase the
high-frequency
performance, compared to that provided by low-energy BF2 ion
implantation. RVD produced a transistor with f
T of 50-GHz
and r
b of
400-Ω. These parameters are 20% higher and 15% lower than
those
of a
transistor produced by BF2
implantation. Low base resistance also
led to an increase in the maximum
oscillation frequency f
max to over 40 GHz in
transistors with longer
emitter. A two-dimensional profile
simulation clarified that RVD can form
a shallower intrinsic base profile and
a deeper link base profile than those
formed by BF2 ion implantation. These
doping profiles made it possible to
increase f
T and f
max, and to reduce
r
b simultaneously.
Improvement of the Visible Electroluminescence from Nanocrystalline Silicon Embedded in CaF2 on Si(111) Substrate Prepared by Rapid Thermal Annealing
Authors: Takeo Maruyama Takeo Maruyama , Naoto Nakamura Naoto Nakamura , Masahiro Watanabe Masahiro Watanabe
Published: October 2002

Electroluminescence (EL) from
nanocrystalline Si (nc-Si) embedded in a single-crystal CaF2 layer
formed on a p-type Si(111) substrate has been demonstrated.
Nc-Si/CaF2 layers were grown by co-evaporation of Si and CaF2 by molecular beam epitaxy for Si and partially ionized epitaxy for CaF2 at a low growth temperature,
followed by rapid thermal annealing (RTA) in N2 ambient.
The crystal growth and annealing conditions were optimized by
investigation of the surface morphology and photoluminescence (PL) intensity.
Visible EL was observed at room temperature in the dark with the naked eye,
from the entire surface of the transparent electrode for current injection.
The uniformity and intensity of the luminescence was drastically improved by RTA in N2 ambient.
High Channel Mobility in Inversion Layer of SiC MOSFETs for Power Switching Transistors
Authors: Hiroshi Yano Hiroshi Yano , Taichi Hirao Taichi Hirao , Tsunenobu Kimoto Tsunenobu Kimoto , Hiroyuki Matsunami Hiroyuki Matsunami
Published: October 2002

A high channel mobility in inversion layers of 4H- and 6H-SiC
metal-oxide-semiconductor field-effect-transistors (MOSFETs)
was successfully achieved by using the (1120)
face instead of the conventional (0001) Si-face.
For 4H-SiC, the channel mobility on the (1120) face
(95.9 cm2/Vs) was
dramatically improved to be 17 times higher than that on the (0001) face
(5.6 cm2/Vs).
For 6H-SiC, the channel mobility on the (1120) face (115.7 cm2/Vs)
was also improved to be 2.5 times higher than that on the (0001) face
(44.8 cm2/Vs).
These results suggest that the MOS interface quality on the (1120) face
is superior to that on the (0001) face.
In the case of the (0001) face, 15R-SiC MOSFETs showed a higher channel
mobility (59.2 cm2/Vs) than 6H-SiC, due to a higher bulk mobility
in 15R-SiC than 6H-SiC.
Etching Characteristics and Mechanism of Ba0.7Sr0.3TiO3 Thin Films in an Inductively Coupled Plasma
Authors: Wuu Dong-Sing , Liao Fang-Ching , Kuo Nei-Hao , Horng Ray-Hua , Lee Ming-Kwei
Published: October 2002

The inductively-coupled-plasma (ICP) etching behavior of
Ba0.7Sr0.3TiO3 (BST)
thin films has been characterized with Cl2/CF4,
Cl2/SF6 and Cl2/Ar gas
mixtures. CF4
and SF6 were found to impede the etch process, presumably due to
competition
between plasma deposition and etching. A chemically assisted etch of
BST was
obtained under various Cl2/Ar gas mixtures. The etch profile along
with etch
anisotropy was observed as a function of etching parameters by
scanning electron
microscopy. The surface morphologies after etching were analyzed by
atomic force
microscopy. A smooth surface (roughness ∼1.8 nm) with no
residue was
observed
under 30%Cl2 in Ar/Cl2, ICP power of 1 kW, substrate bias
of 500 V,
and 10 mTorr.
To clarify the etching mechanism, the surface reaction of the BST thin
films was
investigated by X-ray photoelectron spectroscopy. It was found that Ba
was mainly
removed by chemically assisted physical etching (possible products
such as BaCl
x
).
Physical bombardment is more effective than Cl chemical reaction for
removing Sr,
while Ti can almost be removed by chemical reaction (such as
TiCl
x
). The etching
results described correlate well with the thermochemical
calculations.
Fabrication of the Si/Al2O3/SiO2/Si Structure Using O2 Annealed Al2O3/Si Structure
Authors: Ishida Makoto , Hori Hirotsugu , Kondo Fumitaka , Akai Daisuke , Sawada Kazuaki
Published: October 2002

The formation of a SiO2 layer in the interface between epitaxial
Al2O3(100) and a Si(100) substrate, in order to improve the insulation, was
studied using O2 annealing at 1000°C, and the
Al2O3(100)/SiO2/Si(100) structure was proposed as a Si-on-insulator
(SOI) substrate. The breakdown voltage property of Al2O3/SiO2/Si,
rather than that of the Al2O3/Si structure, was improved from 8 V to
50 V. Moreover, Si(100) growth on the Al2O3/SiO2/Si structure was
carried out, and the morphology of the Si top layer was very smooth.
Metal-oxide-semiconductor field effect transistors (MOSFETs) on the substrates show
excellent electrical properties, which indicates the high crystallinity of SOI.
Submicron Ferroelectric Capacitors Fabricated by Chemical Mechanical Polishing Process for High-Density Ferroelectric Memories
Authors: Igarashi Yasushi , Tani Kouichi , Kasai Masanori , Ashikaga Kinya , Ito Toshio
Published: October 2002

Submicron ferroelectric capacitors were fabricated by a damascene process
using chemical mechanical polishing (CMP). The fabricated capacitors consisted of
SrBi2Ta2O9 (SBT) film with top and bottom electrodes of IrO2
films. The capacitor size was 0.8 µm in diameter, that is, 0.5 µm2 in
area. Damage by the fabrication process was not observed in electrical measurements,
such as the dependence of remanent polarization on electric field and leakage current
properties. The remanent polarization (2Pr) of 5 µC/cm2 at the saturation
voltage of 2 V is half that of a large capacitor because the SBT films were composed
of single-crystal grains in the bismuth-layered perovskite structure and
micro-crystals in many phases including pyrochlore. The crystallinity of the SBT films
may be associated with the redistribution of Bi between the SBT thin films and the
IrO2 electrodes during the crystallization annealing of SBT.
Sub-1.3 nm Amorphous Tantalum Pentoxide Gate Dielectrics for Damascene Metal Gate Transistors
Authors: Inumiya Seiji , Yagishita Atsushi , Saito Tomohiro , Hotta Masaki , Ozawa Yoshio , Suguro Kyoichi , Tsunashima Yoshitaka , Arikado Tsunetoshi
Published: October 2002

The formation process of amorphous tantalum pentoxide
(Ta2O5) gate dielectrics was developed for sub-0.1 µm
damascene metal gate transistors. Ta2O5 film deposition at
high temperature (550°C) on ultrathin (1 nm) oxynitride
interface layer improves the surface morphology and decreases the
carbon contamination in films. Elimination of post-deposition
annealing suppresses the increase of interface layer thickness, and
hence, ultrathin equivalent oxide thickness is obtained and good
interface characteristics are maintained. The relative dielectric
constant of this high-temperature as-deposited film is 26.5 and
leakage current reduction of more than two orders of magnitude,
compared to that in the case of silicon oxide, is obtained in the
sub-2 nm region. A high-performance 90 nm transistor was
successfully realized, by applying amorphous Ta2O5 gate
dielectrics to damascene metal gate transistor processes. This was
due to absence of gate depletion, ultrathin gate dielectrics and
excellent interface properties.
Composition Control of Pb(ZrxTi1-x)O3 Thin Films Prepared by Metalorganic Chemical Vapor Deposition
Authors: Nagashima Kuniharu , Funakubo Hiroshi
Published: October 2002

PbO, ZrO2, TiO2 and Pb(Zr
x
Ti1-x
)O3 (PZT) films were prepared by metalorganic chemical vapor deposition
(MOCVD) using Pb(C11H19O2)2, Zr(O·t-C4H9)4, Ti(O·i-C3H7)4 and O2 as source materials. The
deposition rates of the constituent metals of Pb(Zr
x
Ti1-x
)O3 (PZT) film were investigated as
functions of the input gas flow rate of the source materials and the deposition temperature.
Composition ratios of the PZT film became constant when the Ar carrier gas flow rate of the Pb
source was above 100 cm3/min at 500°C. This suggests that a self-correcting composition region
exists for this input gas composition at 500°C. The deposition rates of each of the constituent
metals of the PZT films were quite different from those in the corresponding single-oxide films, PbO,
ZrO2, and TiO2 films. Therefore, the composition ratio of the PZT film could not be estimated
from the deposition rates of the corresponding single-oxide films. The deposition temperature
dependence of the deposition rates of Ti and Zr in the PZT films was almost the same. This
results in the Zr/(Zr+Ti) ratio being independent of the deposition temperature. However, the
deposition behavior of Pb was different from those of Ti and Zr. Therefore, the Pb/(Pb+Zr+Ti)
ratio must be adjusted by changing the input gas flow rate of the Pb source when the deposition
temperature is changed.
Impacts of Self-Aligned Epitaxial Silicon Sliver (SESS) in Buried Channel-pFETs Elevated Source/Drain Using Dual-Spacer Structure
Authors: Lee Jung-Ho , Yeo In-Seok , Kwak Heung-Sik , Kim Chung-Tae
Published: October 2002

Excellent short channel and junction characteristics in buried channel p-type field
effect transistors (BC-pFETs) are obtained using the elevated source/drain (ESD)
structure with a self-aligned shallow sliver of boron implanted epitaxial silicon. By
employing a dual-spacer structure using high temperature oxide (HTO) and nitride, a
self-aligned epitaxial silicon sliver (SESS) protruding laterally into the bottom edge of
gate sidewall spacers is intentionally formed to reduce the series resistance of
source/drain extension of BC-pFET while minimizing the faceting. The trade-off
relation between SESS and facet developments is revealed by the control of
HTO thickness. As a result, the short channel characteristics of ESD employing SESS
are improved without decreasing current drivability for sub-0.25 µm pFETs. Cumulative
characteristics of p+-n junction leakage and the contact resistance are also
remarkably improved using the elevated junction structure.
Study of Optimization Guidelines on Nitrogen Concentration in Nitrided Oxide for Logic and Dynamic Random Access Memory Application
Authors: Jung Jong-Wan , Park Sung-Kye , Yoon Gyu-Han , Kang Dae-Kwan , Lee Youngjong
Published: October 2002

In this paper, we report on the issues and optimization
guidelines for nitrided oxide (NO) gates for logic and dynamic
random access memory (DRAM) devices. We intensively studied the
dependence of device characteristics on the nitrogen concentration
in NO gates. In the case of logic devices, degradation of short
channel characteristics in n-channel metal oxide semiconductor
field effect transistors (NMOSFETs) and
degradation of drive current in p-channel MOSFETs (PMOSFETs)
limits the maximum nitrogen concentration. In DRAMs, an additional
V
T dose to compensate for the decrease of V
T
in NO gates causes a
degradation in the refresh time performance due to the increase of
the electric field in the space-charge region. This reveals that,
for NO-gate DRAM, the nitrogen concentration should be minimized to
prevent the degradation of refresh characteristics.
Comprehensive Study of a New Self-Convergent Programming Scheme for Split Gate Flash Memory
Authors: Chou Amy Hsiu-Fen , Wong Wei-Zhe , Yang Evans Ching-Song , Yao Yu-Yuan , Wang Yen-Sen , King Ya-Chin , Hsu Charles Ching-Hsiang
Published: October 2002

A new self-convergent constant current programming achieved by a
ramp-up source voltage is extensively studied in this work. Based on
the results of a constant programming current and self-convergent
characteristics, several methods are presented to achieve accurate
control of multiple programmed states. Both efficient programming
speed and excellent reliability are demonstrated. The proposed
programming technique is considered to be a promising candidate for
high-speed, high-density, and low-power multilevel split gate flash
memory.
New Approach to Negative Differential Conductance with High Peak-to-Valley Ratio in Silicon
Authors: Koga Junji , Vanderstraeten Celine , Takagi Shin-ichi , Toriumi Akira
Published: October 2002

In this paper we report a new approach to realize negative
differential conductance (NDC) with a high peak-to-valley (P/V)
ratio in silicon metal-oxide-semiconductor field effect transistors
(Si MOSFETs). A P/V ratio of as large as 10 at room temperature has
been demonstrated by controlling the effective biasing to p-MOSFETs
fabricated on a silicon-on-insulator (SOI) wafer. Although the
band-to-band tunneling current is
utilized, the excess tunneling current which has ever limited the P/V
ratio in the Si Esaki diode is eliminated in the proposed
method. Higher P/V ratio will enable us to incorporate NDC
functionality into future Si large-scale integrated (LSI) circuits and
open up new possibilities for LSI applications.
Suppression of Substrate Crosstalk in Mixed-Signal Complementary MOS Circuits Using High-Resistivity SIMOX (Separation by IMplanted OXygen) Wafers
Authors: Kodate Junichi , Harada Mitsuru , Tsukahara Tsuneo
Published: October 2002

We investigated the effectiveness of high-resistivity SIMOX (Separation by
IMplanted OXygen) wafers to suppress substrate crosstalk. Small- and large-signal
crosstalk measurements yielded similar results, which indicated that the frequency
dependence of both types of crosstalk could be understood by analyzing the small-signal
data. With the measured data, we constructed a model of substrate crosstalk with
lumped elements, and found that the model described substrate crosstalk accurately.
We also measured the crosstalk between actual digital and analog circuits. The
measured and calculated data showed that high-resistivity SIMOX wafers could reduce
substrate crosstalk by 5–10 dB in mixed-signal complementary
metal-oxide-semiconductor (CMOS) circuits. Hence, we concluded that using
high-resistivity SIMOX wafers was an effective way to suppress substrate crosstalk
in mixed-signal CMOS circuits.
Admittance Spectroscopy and Thermal Stimulation Current for Band-Offset Characteristics in AlAs/GaAs n+-p Structures
Authors: Chen Jenn-Fang , Wang Jin-Shung , Wang Pai-Yong , Chen Nie-Chuan , Hsu Nian-Ching
Published: October 2002

Admittance spectroscopy is used to study a molecular-beam epitaxially
grown GaAs n+-p diode with 100-Å-thick AlAs immersed in the lightly doped
p-region. The measurements clearly show two trapping effects. Upon
comparison with the reference sample without the AlAs layer, an equivalent
circuit for the studied sample is developed. Based on this circuit, the
admittance spectra are calculated and found to be consistent with the
experimental spectra. From this result, the trap at E
a=0.52 eV with a capture
cross section 1.6×10-14 cm2 is believed to result from the
resistance-capacitance time constant effect due to the thermionic emission of holes over
the AlAs barrier and the activation energy corresponds to the AlAs/GaAs
valence-band offset. The results of the thermal stimulation current further
support this conclusion.
A Low Power Multiplier Using Adiabatic Charging Binary Decision Diagram Circuit
Authors: Nakata Shunji , Douseki Takakuni , Kado Yuichi , Yamada Junzo
Published: October 2002

An adiabatic charging binary decision diagram circuit (AC-BDD) is proposed that
uses pass transistor logic based on a BDD and is operated by four power clocks. The
AC-BDD circuit has the characteristics of a gate-level pipeline. Also proposed is a
simplified switched capacitor regenerator that operates stably at any time even if the
load capacitance changes variously. An 8×8 bit multiplier was designed using
0.25-µm CMOS/SIMOX (Complementary MOS/Separation by IMplanted OXygen)
technology to confirm charging recovery. We found that the multiplier operates at
0.2 V and 1 MHz and its power consumption can be decreased to less than 10% that
of CMOS logic.
Room Temperature Coulomb Oscillation of a Single Electron Switch with an Electrically Formed Quantum Dot and Its Modeling
Authors: Kim Dae Hwan , Lee Jong Duk , Park Byung-Gook
Published: October 2002

The room temperature operation of a single electron switch
fabricated by conventional Si large-scale integration (LSI)
technologies has been demonstrated. The quantum dot formed by the
electric field effect of a dual gate structure was miniaturized to a
smaller size than the state-of-the-art feature size, using the
controllable process technologies such as polysilicon reoxidation
and polysilicon sidewall formation. Electrical measurement showed a
room temperature Coulomb oscillation and a movement of the
oscillation peak in two independently controllable tunnel
junctions. Based on the device physics, the modified macro modeling
of fabricated single electron switches was performed. Existing
concept of single electron transistor (SET) macro modeling was first
applied to the experimental result, and the circuit performance of
the fabricated device was effectively predicted using this modeling
scheme.
Area-Controlled Growth of InAs Quantum Dots by Selective MOCVD
Authors: Tatebayashi Jun , Ishida Satomi , Nishioka Masao , Someya Takao , Arakawa Yasuhiko
Published: October 2002

A technique to control the location of quantum dot growth is required to avoid
optical absorption and attain high reflectivity in fabricating quantum dot lasers with
photonic crystal reflectors in the same growth plane as the active layer. In this paper,
we demonstrate a novel scheme for area-controlled growth of quantum dots using
selective metal organic chemical vapor deposition (MOCVD). Using this technique, the
deposition of material within mask windows can be controlled by varying the width of
the SiO2 mask. By optimizing the growth conditions and mask pattern, a high
density (2.4×1011/cm2) of quantum dots was formed selectively only in
the active layer of a laser structure, while no quantum dots were formed in the
reflector region.
Low Crosstalk and Low Loss Polymeric 1×8 Digital Optical Switch
Authors: Ooba Naoki , Toyoda Seiji , Kurihara Takashi
Published: October 2002

We have demonstrated a high-performance 1×8 digital thermo-optic (TO)
switch that uses silicone resin waveguides. The compact 40 mm long switch employs
short Y-branching switches with a large branching angle. It has a low insertion loss of
less than 3 dB and a low crosstalk of less than -40 dB at 1550 nm. The switch
characteristics are maintained over wide wavelength regions around 1.3 and
1.55 µm. They are also stable over a wide temperature range of -10 to
75°C and a humidity range of 30 to 90%RH.
Metal-Organic Vapor-Phase Epitaxial Growth and Characterization of Quaternary AlGaInN
Authors: Han Jung , Figiel Jeffrey J. , Petersen Gary A. , M. Myers Samuel , Crawford Mary H. , Banas Michael A.
Published: October 2002

We report the growth and characterization of quaternary AlGaInN. A combination of
photoluminescence (PL), high-resolution X-ray diffraction (XRD), and Rutherford
backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant-PL peak energy and lattice parameter as functions of the quaternary
compositions. The observation of room temperature PL emission at 351 nm (with 20%Al
and 5%In) renders initial evidence that the quaternary could be used to provide
confinement for GaInN (and possibly GaN). AlGaInN/GaInN multiple quantum wells
(MQWs) heterostructures have been grown; both XRD and PL measurement suggest the
possibility of incorporating this quaternary into optoelectronic
devices.
Growth of Bulk GaN Single Crystals by the Pressure-Controlled Solution Growth Method
Authors: Inoue Takayuki , Seki Yoji , Oda Osamu , Kurai Satoshi , Yamada Yoichi , Taguchi Tsunemasa
Published: October 2002

We are the first researchers to have developed the
pressure-controlled solution growth (PC-SG) method. Using this
method, supersaturation of growing crystals is realized by applying
an over pressure without any temperature decrease. We applied this
method to the growth of GaN crystals for examining the validity of
the PC-SG method, using a high-pressure furnace. It was determined
that the crystal growth rate increased as a function of temperature
with a maximum at 1475°C under a nitrogen pressure of 0.98 GPa. The
dependency of the growth rate on the Ga metal weight strongly
supports the fact that the dominant growth process is by diffusion
of nitrogen atoms in the Ga melt. GaN single crystals with a maximum
size of 10 mm diameter were reproducibly grown by the PC-SG method
and it was determined that these crystals had good crystallinity.
Hydride Vapor Phase Epitaxy of GaN on NdGaO3 Substrate and Realization of Freestanding GaN Wafers with 2-inch Scale
Authors: Wakahara Akihiro , Yamamoto Takenori , Ishio Kouji , Yoshida Akira , Seki Youji , Kainosho Keiji , Oda Osamu
Published: October 2002

GaN thick film is grown on NdGaO3 substrate using hydride vapor phase epitaxy. To
avoid decomposition of NdGaO3 substrate by NH3, a low-temperature grown GaN
protective layer is adopted. Using NdGaO3 substrate and a low-temperature GaN
protective layer simultaneously, 2-inch-scale GaN wafers are realized. The photoluminescence (PL) spectrum
indicates strong band-edge emission without deep-level related emission. Both plan-view transmission electron microscope and cathode luminescence images suggest that
the dislocation density of freestanding GaN wafers is expected to be
as low as 106 cm-2.
Piezoelectric Polarization in GaInN/GaN Heterostructures and Some Consequences for Device Design
Authors: Wetzel Christian , Amano Hiroshi , Akasaki Isamu
Published: October 2002

The polarization properties of doped
Ga0.85In0.15N/GaN multiple quantum well structures
are investigated under the application of external bias voltages.
From Franz-Keldysh oscillations at and above the barrier band
edge, the electric field in the barriers is determined.
From the bias dependence, we derive the polarity and an
offset of 0.51 MV/cm of the internal field.
This is attributed to the piezoelectric polarization in the
well region of magnitude P = -e
z (0.009 - 0.
014) C/m2. We find that Si doping at typical concentrations of
3 ×1018 cm-3 cannot screen the polarization
effects on the length scale typical for quantum wells and
superlattices but induces large potential barriers.
Microwave Performance of 0.3-µm Gate-Length Multi-Finger AlGaN/GaN Heterojunction FETs with Minimized Current Collapse
Authors: Kunihiro Kazuaki , Kasahara Kensuke , Takahashi Yuji , Ohno Yasuo
Published: October 2002

We have fabricated multi-finger AlGaN/GaN heterojunction field
effect transistors (HJFETs) with a sub-half-micron gate-length on a
sapphire substrate that are suitable for near-millimeter-wavelength
applications. Fabricated HJFETs with a 0.25-µm gate-length had a
small-signal power-gain high enough for K- and Ka-band applications,
i.e., a cut-off frequency of 40 GHz, a maximum oscillation
frequency of 97 GHz, and a maximum stable gain of 11.8 dB at
30 GHz. This high-frequency performance is attributed to the small
parasitic capacitance enabled by air-bridge interconnection as well
as to the sub-half-micron gate length formed by electron-beam
lithography. The air-bridge interconnection also prevented
surface-induced current collapse. Because the current-collapse was
negligible, an HJFET with a 1.2-mm gate-width exhibited steady
large-signal RF performance, i.e., a saturation output power of
1.47 W (1.22 W/mm) with a power-added efficiency of 51.5% at
1.95 GHz.
Electron and Hole Proximity Effects in the InAs/AlSb/GaSb System
Authors: H. Roslund Jöran , Saito Ken , Suzuki Kyoichi , Yamaguchi Hiroshi , Hirayama Yoshiro
Published: October 2002

We have investigated the properties of InAs/AlSb/GaSb
electron–hole proximity systems while focusing on the influence of the AlSb barrier
between the two quantum wells. We have seen that for thin AlSb barriers
there is a drop in mobility due to scattering of electrons by holes. We have
also observed a series of secondary absorption peaks in cyclotron resonance
spectra that are caused by interband Landau-level transitions.
In Situ Controlled Growth of Low-Temperature GaAs and Its Application for Mode-Locking Devices
Authors: Herfort J. , Apostolopoulos G. , Friedland K.-J. , Kostial H. , Ulrici W. , Däweritz L. , Leitner M. , Glas P. , Ploog K. H.
Published: October 2002

We report on the potential of reflectance difference spectroscopy (RDS) in realizing
high reproducibility, optimization of growth conditions, and in situ control for growth of extremely thick high quality GaAs layers at low substrate temperatures (LT). The amplitude of
the observed anisotropy in the RDS caused by the linear electro-optic effect is directly related
to the incorporated As antisite density. Therefore, in situ RDS allows a real time determination of nonstoichiometry and hence, of the electrical and optical properties of the layers. We
show that extremely thick LT-GaAs layers (up to 14 µm) grown by molecular beam epitaxy (MBE) with optimized
growth parameters can be successfully implemented as a material for obtaining self-starting
mode-locking of a Nd:glass fiber laser.
A High-Efficiency CMOS Class-B Push-Pull Power Amplifier for Code-Division-Multiple-Access Cellular System
Authors: Yokoyama Michio , Saito Tetsuya , Tachibana Ryoichi , Morimoto Akihiro , Masu Kazuya , Tsubouchi Kazuo
Published: October 2002

A silicon Class-B complementary push-pull power amplifier for a code-division-multiple-access IS-95 cellular system has been proposed for the first time. 0.8-µm
complementary metal-oxide-semiconductor (CMOS) devices are fabricated and
evaluated using RF measurement and simulation. The RF-CMOS balanced design
between n- and p-MOS devices has been investigated. From RF simulation, a power-added efficiency (PAE) of over 60% at an input power of 5 dBm and an adjacent-channel-power-ratio of -42 dBc are obtained. It is found that both high efficiency and
high linearity are obtained using the RF-CMOS balanced design with optimized channel
length and width. Furthermore, drain voltage control for IS-95 criteria has been
proposed in addition to the balanced design. The overall PAE, which is defined as the
PAE multiplied by the probability distribution function of the used power-level and
integrated over the entire used power range, has been improved up to 49%.
Influence of Organic Contamination on Silicon Dioxide Integrity
Authors: Sugimoto Fumitoshi , Okamura Sigeru , Inokuma Takao , Kurata Yoshihiro , Hasegawa Seiichi
Published: October 2002

The influence of organic contamination before oxidation on 8-nm-thick silicon
dioxide integrity was studied. Contamination results from the intentional adsorption of
dioctyl phthalate (DOP) on silicon wafers. Metal-oxide semiconductor (MOS) capacitors
were fabricated on the wafers to measure the electrical characteristics of the oxide. A
reduction in the dielectric breakdown field strength of the oxide was found to occur
after DOP adsorption of more than 1×1013 mol/cm2. The flat-band
voltage shift (ΔV
fb) and interface trap charge density
(D
it) increased with an increase in the amount of DOP below
1×1013 mol/cm2. Positive charges arose from DOP in the oxide during
oxidation, which was determined from a negative ΔV
fb. Furthermore,
with an increase in the DOP level from 1×1013 to
1×1015 mol/cm2, D
it hardly increased whereas
ΔV
fb gradually increased. This suggests that positive charges at the
silicon-oxide interface are fixed. It is thought that an increase in the amount of
positive charge in the oxide reduces the dielectric breakdown voltage. From infrared
(IR) adsorption measurement, we found that even after DOP decomposition due to
oxidation, positive charges within DOP remained, and they degrade oxide integrity.
X-Ray Photoelectron Spectroscopy Study of a Self-Assembled Monolayer of Thiophene Thiol
Authors: Okawa Haruki , Wada Tatsuo , Sasabe Hiroyuki , Kajikawa Kotaro , Seki Kazuhiko , Ouchi Yukio
Published: October 2002

A thiophene derivative containing a thiol group,
(3-thienylethyl)-11-mercaptoundecanoate, was deposited on a gold
surface. The thiophene monomer formed a self-assembled monolayer
(SAM). The structure of the SAM was characterized by X-ray
photoelectron spectroscopy (XPS). The molecules were adsorbed at the
thiol group with end-on configuration. Using the ratio of signal
intensity of the two types of sulfur atoms in the thiol and thiophene
groups, the escape depth of a photoelectron of the SAM was estimated
to be 30 Å, which is slightly longer than the empirical value of
33 Å for SAMs of alkanethiols. This is because the bulky
thiophene ring and the flexible ester group prevent the monolayer from
forming a densely packed structure like the alkanethiol SAMs.
The Thermal Conversion Efficiency in YBa2Cu3O7-δ Microbridges for Optical Detection
Authors: Hong Meng-Tsong , Jen Chung-Wei , Chu Hsin-Her , Chow Timothy-Chi , Chen Ying-Chung , Chou Hsiung
Published: October 2002

For ideal mid-transition YBa2Cu3O7-δ (YBCO) optical
detection, the maximum value of the photoresponse, ΔV
max, should
linearly correspond to (d
R/d
T)max, and the temperature rise ΔT be
constant under the same measurement conditions. However, in this study, both the
experimental and simulation results showed that the ratio of the temperature rise to
irradiated power density, ΔT/W
D, was no longer constant but was
dependent on the geometry of microbridges, which resulted in the non-linearity of
ΔV
max on (d
R/d
T)max. Actually, ΔT/W
D
represent the thermal conversion efficiency of the detector, and is a matter of the
absorption of the AC thermal irradiation and the dissipation of both the irradiation and
the DC joule heat generated by the bias current. The competition between the capability
of heat dissipation and the thermal generation determined the magnitude of
ΔT/W
D. The geometry plays a very important role on the behavior of
heat conduction, thermal conversion efficiency and photoresponse in YBCO
microbridges.
Ultrashallow Junction Formation by Rapid Thermal Annealing of Arsenic-Adsorbed Layer
Authors: Song Yun-Heub , Park Ki-Tae , Kurino Hiroyuki , Koyanagi Mitsumasa
Published: October 2002

Ultrashallow junction formation in sub-0.1 µm metal oxide semiconductor field effect transistor (MOSFET) fabrication has been focused on as a key process technology. In this work, the arsenic (As) doping method, with rapid thermal annealing of the As-adsorbed layer with a capping oxide, was investigated for the first time as a technique for shallow junction formation. The As-adsorbed layer is successfully fabricated by AsH3 injection into the gas-source molecular beam epitaxy (GSMBE) apparatus. As-layer doping provides an extremely shallow junction (X
j: 20 nm) with a low sheet resistance (below 2 kΩ/sq.), thus proving to be a superior technique for shallow junction formation in the source/drain extension region of N-channel MOSFETs.
Determination of Second-Order Nonlinear Optical Susceptibility of GaN Films on Sapphire
Authors: Takashi Fujita Takashi Fujita , Tatsuo Hasegawa Tatsuo Hasegawa , Masanobu Haraguchi Masanobu Haraguchi , Toshihiro Okamoto Toshihiro Okamoto , Masuo Fukui Masuo Fukui , Syuji Nakamura Syuji Nakamura
Published: October 2002

The second-order nonlinear susceptibilities of GaN films on sapphire were determined by the Maker fringe technique. In deriving the second-harmonic intensity, the bound wave propagating from the GaN-air interface to the GaN-sapphire interface and that propagating in the opposite direction were taken into account. We obtained |χ(2)

z
x
x
|=14.7±0.2 pm/V, |χ(2)

x
z
x
|=14.4±0.2 pm/V and |χ(2)

z
z
z
|=29.7±0.7 pm/V for the GaN film with a thickness of 2.55 µm using fundamental light with a wavelength of 1.064 µm.
Improved Performance of Fast-Axial-Flow, RF-Discharge-Excited, Room-Temperature CO Laser with Kr-Added Mixtures
Authors: Shimizu Kouki , Taniwaki Manabu , Sato Shunichi , Nagano Hiroshi , Maeno Kazuo
Published: October 2002

The fast-axial-flow, RF-discharge-excited, room-temperature CO laser greatly
increased the specific output power, from 2.2 W/cm3 (electrical conversion
efficiency: 9.5%) in the absence of Kr gas to 3.9 W/cm3 (electrical conversion
efficiency: 16.5%), by adding Kr gas to the laser gas. Kr addition is considered to have
various effects, including the increase in the vibrational excitation efficiency of CO
molecules due to the lowering of mean electron energy, the increase in electron
density, and reduction in CO2 concentration due to the decrease in electrically
excited CO molecules. Among these effects, the increase in vibrational excitation
efficiency and electron density have been found to be significant. The effect is
improved up to over 80% of the Xe addition effect.
Digital Versatile Disc/Compact Disc-Compatible Pickup Head with Dual-Lens Lever Actuator for Next-Generation Applications
Authors: Han Changsoo , Lee Junghyun , Kim Soohyun
Published: October 2002

As the track density and disc rotational speed of digital
versatile disc (DVD) increase rapidly, an optical pickup head with
better performance is required. In this paper, the design
requirements of pickup heads aiming at high speed and high recording
density are discussed. A new pickup head with a dual-lens lever
actuator is proposed. The prototype of the lever actuator is
fabricated, and the measurement results are compared with the
analysis results. The experimental results show that the new pickup
head can be used for the DVD system, and satisfies the requirements
of high-density and high-speed.
Oxygen Doping Effects on Super-resolution Scattering-mode Near-field Optical Data Storage
Authors: Men Liqiu , Tominaga Junji , Fuji Hiroshi , Atoda Nobufumi
Published: October 2002

Silver oxide (AgO
x
) was recently proposed as a new mask material to realize
a scattering-mode super-resolution near-field structure (Super-RENS). To obtain a
further understanding of the influence of the Ge2Sb2Te5 recording layer
on the characteristics of scattering-mode Super-RENS, oxygen (O2)-doped GeSbTe
films are examined in this study. The crystallization temperature T
c of the
GeSbTe–(O) films increased with the O2 flow ratio and was improved to
200°C at the O2 flow ratio of 0.1. It was found that light O2 doping
could improve the super-resolution to 80 nm and the readout durability against
readout cycles in the scattering-mode Super-RENS could be greatly improved by light
and heavy O2 doping into GeSbTe films.
Single-Electron Tunneling Devices Based on Silicon Quantum Dots Fabricated by Plasma Process
Authors: Dutta Amit , Lee Shao Ping , Hayafune Yoshinori , Hatatani Shigo , Shunri Oda Shunri Oda
Published: October 2002

A study of the electrical properties of multiple tunnel junctions (MTJs) formed in a quasi one-dimensional array of randomly deposited silicon nanocrystals is presented. Nanocrystals are deposited by very-high-frequency (VHF) plasma decomposition of silane. The average dot diameter is 8 nm. The source-drain electrode separation is 30 nm. A gate electrode is employed so that the charge states in quantum dots can be controlled. A study of the source-drain current–voltage (I–V) characteristics with various gate voltages is performed. Coulomb blockade, a Coulomb staircase and Coulomb oscillations are observed at temperatures ranging from 40 K to 150 K. Single electron trapping is observed at 40 K.