bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of Ba2NaNb5O15 Thin Films on MgO(100) by the Pulsed Laser Ablation Method
Authors: Ando Shizutoshi , Konakahara Kaoru , Okamura Soichiro , Tsukamoto Takeyo
Published: October 2002

Ba2NaNb5O15 (BNN) thin films were grown on MgO(100) by the pulsed laser ablation method
using BNN ceramic targets. The characterization of the thin films was carried out by X-ray
diffraction, a scanning electron microscope and an electron probe micro analyzer. The chemical
composition of BNN thin films approached the BNN stoichiometry and improved with increasing
O2 gas pressure. We obtained the BNN single phase thin films with strong c-axis orientation and
nearly stoichiometoric composition deposited on MgO(100) at the laser energy density of 5.0 J/cm2,
the substrate temperature of 600°C and the O2 gas pressure of 0.3 Torr.
Growth of ZnO Thin Films on LiNbO3 Substrates by Electron Cyclotron Resonance-Assisted Molecular Beam Epitaxy
Authors: Hee-Bog Kang Hee-Bog Kang , Kenji Yoshida Kenji Yoshida , Kiyoshi Nakamura Kiyoshi Nakamura
Published: October 2002

In this paper, we describe the growth of high-quality ZnO heteroepitaxial films on LiNbO3 (0001) substrates by electron cyclotron resonance-assisted molecular beam epitaxy (ECR-assisted MBE). The quality of these films is analyzed by means of X-ray diffraction, pole figure of X-ray diffraction, and reflection high-energy electron diffraction (RHEED). The FWHM value of the (002) rocking curve for the 0.3-µm-thick films grown at 250°C was 0.45°. The pole figure of X-ray diffraction studies revealed that the films were epitaxial with a 30° rotation of the unit cell with respect to LiNbO3 in the (0001) basal plane. The lattice mismatch between [1210]ZnO and [1100]LiNbO3 was about 8.3%, which is smaller than that (∼16%) of ZnO film on sapphire (0001) that is widely used as a substrate. The growth of ZnO films on interdigital transducers (IDTs)/LiNbO3 was also studied. The films deposited over the bare LiNbO3 area between finger electrodes were single crystalline, while the films deposited over the Cr-Au finger electrodes were polycrystalline.
Influence of Target Shape on Properties of AlN Sputtered Film
Authors: Tominaga Kikuo , Sato Yoshifumi , Mori Ichiro , Kusaka Kazuya , Hanabusa Takao
Published: October 2002

AlN films were deposited by reactive magnetron sputtering with a roof-shaped Al target and conventional planar target. The c-axis orientation and the grain growth of AlN films were improved and the defects in the film were
decreased, when the ion flux bombarding the film decreased. This trend was
confirmed by depositing AlN films under various N2 gas pressures or external
magnetic fields. These data indicate that there remains a considerable influence of ion bombardment in conventional planar magnetron sputtering, but the use of a rooftype target is effective for decreasing the exposure of the film to plasma as a result of a decrease in ion bombardment.
Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics
Authors: Ogawa Toshio , Nakamura Koji
Published: October 2002

Rhombohedral lead zirconate titanate (PZT) ceramics were evaluated statically and dynamically to examine the relationship between domain structures and electrical properties. The poling field dependence
of the electrical properties and crystal orientation was investigated as a statical evaluation. When the poling field was varied, maximum dielectric constant, minimum planar coupling factor, minimum frequency
constant and minimum relative intensity of the X-ray diffraction (222) peak were obtained at the poling fields of ±0.5, ±1.0, ±0.5 and ±0.75 kV/mm, respectively. Since 180° domain switching was the dominant factor affecting the coupling
factor, it was thought that the electrical domain clamping occurred at ±1.0 kV/mm. Furthermore, responses to repeated voltage pulses applied to the ceramics were measured by a high voltage test system as a dynamical evaluation. From these evaluations,
we could clarify the domain behavior for the switching and clamping of
180° domain, 71° and 109° domain rotations and transient phenomena on the domain orientation.
Effect of Y and Mn Doping in Pb(T, Zr)O3 Piezoelectric Ceramics on the Resonant Frequency and Capacitance Changes and Aging by Thermal Shock Tests
Authors: Takahashi Keiichi , Nishida Masamitsu , Hase Hiroyuki
Published: October 2002

The effects of Y and Mn-doping in Pb(Zr, Ti)O3 (PZT) with respect to the resonant
frequency changes and the aging phenomena caused by thermal treatment were studied in order
to achieve a stable piezoelectric ceramic filter. Good thermal stability as well as a high
mechanical quality factor Q
M were required for the piezoelectric ceramics to fabricate certain
types of narrow band monolithic filters. The Cr-doped PZT showed a little aging phenomena in
resonant frequency change after thermal shock tests, but Q
M was not high. The Cr and Mn-doped
PZT had a large Q
M value, but a large amount of resonant frequency change and aging after
thermal shock tests. It was observed that the PZT with the addition of Y and Mn has high Q
M
and good temperature stability. These features were suitable for the use in filters and resonators.
Effects of B-site Ions on the Electromechanical Coupling Factors of Pb(B′B′′)O3–PbTiO3 Piezoelectric Materials
Authors: Yamashita Yohachi , Harada Kouichi , Hosono Yasuharu , Natsume Shinya , Ichinose Noboru
Published: October 2002

The effect of B-site ions of Pb(B′B′′)O3–PbTiO3 (B′=Zn, Mg, Ni, Ga, Sc, In, Yb and B′′=Nb, Ta) piezoelectric materials on the electromechanical coupling factors has been studied. A
relationship between electromechanical coupling factor k
p near a morphotropic phase boundary
(MPB) and an order/disorder tendency of B-site ions is systematically discussed.
The reason why k
p of Pb[((Sc1/2Nb1/2)0.58Ti0.42)O3 (PSNT59/42) is larger than that of
Pb[(Mg1/3Nb2/3)0.68Ti0.32]O3 (PMNT68/32) or Pb[((Sc1/2Ta1/2)0.58Ti0.42)O3 (PSTT55/45) was
explained in terms of the disorder tendency of B-site ions of Pb(B′B′′)O3–PbTiO3. It may be
concluded that a combination of the B-site elements which have a tendency of disorder play an
important role in bringing about large electromechnical coupling factors in MPB composition.
From this viewpoint, MPB compositions of Pb[((Sc1/2Nb1/2)0.29(Mg1/3Nb2/3)0.34Ti0.37]O3
(PSMNT 29/34/37) and Pb[((Sc1/2Nb1/2)0.36(Ni1/3Nb2/3)0.26Ti0.38]O3 (PSNNT 36/26/38) maybe the
two best combinations among all the Pb((B′B′′)O3–PbTiO3 systems.
Double-D-Depth: A Novel Approach for Depth Sensation
Authors: Haisma Jan , C. J. E. C. J. E. , Seppen Seppen
Published: October 2002

Distance-determined, i.e. distance-supported graded luminance or transparency is a novel imaging feature which is depth-expressive and as such clearly distinguishable from two-dimensional imaging. It is substantiated by two image planes, positioned at a distance from each other, on which image parts, that are in register in both planes, are gradually and complementarily changed in luminances (transparencies) as a function of depth, distance, length, height and/or volume of objects/entities of the real scene. A novel perceivable type of three-dimensional imaging which stems from it, is called “Double-D-Depth”. It can be observed visorlessly. This paper gives mainly a phenomenological description of the principle, including relevant examples, and some perceptual entries.
Trapped Energy Gyroscopes Using Thickness Shear Vibrations in a Partially Polarized Piezoelectric Ceramic Plate
Authors: Abe Hiroshi , Yoshida Tetsuo , Ishikawa Toshihiro , Miyazaki Noriko , Watanabe Hiroshi
Published: October 2002

A new type of gyroscope using energy trapping of thickness-shear vibrations
excited by a parallel electric field is proposed. The vibrator of a trapped-energy
gyroscope is constructed using a partially polarized piezoelectric ceramic plate
and three electrodes on its surface, and the driving-detecting circuit includes
the current detecting circuit. Prior to designing the trapped-energy gyroscope,
a method of controlling the resonant frequency of the vibrator by means of the
electrode dimensions was identified from the measured impedance
characteristics. Based on this method, the trapped-energy gyroscope on a 25-mm-square and 1.5-mm-thick PZT plate is constructed. The detection
sensitivity of 2.8 mV/deg/s, which is proportional to the applied angular velocity, is
obtained when the driving voltage is 2 Vp-p and the gain of the detecting circuit
is 72 dB. Although the edge of the vibrator is firmly attached to the base, the
Q
m of the resonance is over 900 because of the energy trapping effect. This
trapped-energy gyroscope is useful for highly reliable applications such as a
yawing sensor for the vehicle stability control systems.
Measurement of Complex Dielectric Constant above Room Temperature and Its Application to Determination of Intrinsic Dielectric Loss
Authors: Ikeda Masaaki , Miura Taro
Published: October 2002

Measurements of the complex permittivity on single crystal dielectric
materials with different crystal symmetry have been carried out at high
temperatures. The theory of intrinsic dielectric loss proposed by Gurevich et al.. was confirmed for Oh
7 and D3d
6 symmetries. X-ray topography images showed that
crystal disorientation caused a deleterious influence on dielectric loss.
Microwave Dielectric Properties of Y2Ba(Cu1-xZnx)O5 Solid Solutions
Authors: Watanabe Masahiro , Ogawa Hirotaka , Ohsato Hitoshi , Humphreys Colin
Published: October 2002

The microwave dielectric properties of Y2Ba(Cu1-x
Zn
x
)O5 (0≤x≤1) solid solutions, prepared by the solid state reaction method, were studied in relation to the amount of Zn substitutions,
and measured using the Hakki and Coleman method. The ε

r
and the τ
f
increased slightly, and
the Q·f values changed nonlinearly as the amount of Zn substitution was increased. In
particular, it is shown that improved microwave dielectric properties with Q·f=110665 GHz,
ε

r
=14.2 and τ
f
=-41.5 ppm/°C are obtained for samples with x=0.5, which also have few pores and high relative density. Thus, it was concluded that the Q·f values were closely related to the
presence of pores in the samples.
Dielectric Properties of Rare-Earth-Added Cordierite at Microwave and Millimeter Wave Frequencies
Authors: Okamura Takeshi , Kishino Tetsuya
Published: October 2002

Dense cordierite ceramics were obtained by adding rare-earth oxides at sintering
temperatures between of 1355–1420°C. The room-temperature dielectric constants of the
cordierite at microwave and millimeter-wave frequencies were evaluated by using the
dielectric resonator method. The dielectric permittivity (ε
r) and dissipation factor (tan
δ)
were determined to be 4.9 and 1.6×10-4 at 18 GHz, 4.9 and 2.6×10-4 at 59 GHz,
respectively. An 80-mm-long waveguide fabricated with cordierite thus obtained, showed
a low transmission loss (<1 dB) at frequency range of 55 to 65 GHz.
Microwave Dielectric Properties and Far Infrared Reflectivity Spectra of the (Zr0.8Sn0.2)TiO4 Ceramics with Additives
Authors: Kim Woo Sup , Kim Tae Hong , Kim Eung Soo , Yoon Ki Hyun
Published: October 2002

Microwave dielectric properties and far infrared reflectivity spectra were investigated in the
(Zr0.8Sn0.2)TiO4 ceramics with 1 mol% Sb2O5, Sb2O3 and Nd2O3, respectively. Dielectric
constant was not significantly changed, while the unloaded Q value was affected with additives.
The unloaded Q of the pure (Zr0.8Sn0.2)TiO4 specimens was higher than that of the specimens
with Sb2O3 and/or Nd2O3, but lower than that of the specimens with Sb2O5. The high unloaded
Q value of 6600 at 7 GHz was obtained for the specimens with 1 mol% Sb2O5 due to
elimination of oxygen vacancies. The effects of additives on the intrinsic microwave losses of
the specimens were investigated by the infrared reflectivity spectra from 50 to 4000 cm-1,
which were evaluated using the Kramers-Kronig analysis and classical oscillator model. The
relative tendency of microwave dielectric properties calculated from the reflectivity data was in
good agreement with the results by the Hakki and Coleman's method.
Temperature Dependence of Switching Characteristics in Polyurea-5 Thin Films
Authors: Tajitsu Yoshiro , Ishida Kazufumi , Kanbara Shintarou , Ohigashi Hiroji , Date Munehiro , Fukada Eiichi
Published: October 2002

In order to investigate the ferroelectric properties of
polyurea-5 prepared by vapor-deposition polymerization, we used
switching measurements and found that polyurea thin films showed
ferroelectric polarization reversal behavior. Ferroelectric
switching transients with the amount of reversed polarization P
r of
20 mC/m2 were observed for the polymer thin film at room temperature.
This P
r is consistent with a polyurea-5 film crystallinity of 30%.
We then found a two-step increase in the switching transients above
50°C. The first increase gives P
r of 20 mC/m2 and the second increase
gives a large P
r increment of 200 mC/m2 which is much larger than the
calculated value of the spontaneous polarization in the single crystal
of polyurea-5. However the second increase with P
r of 200 mC/m2 is
almost independent of applied field E and shifts to short time regions
with increasing E. These results imply that the second increase with
P
r of 200 mC/m2 is caused by ferroelectric switching.
Principle and Application of Crystallo-optical Effects Induced by Inhomogeneous Deformation
Authors: Vlokh Rostyslav , Kostyrko Myroslav , Skab Igor
Published: October 2002

The influence of inhomogeneous fields on the optical properties of crystals is discussed on the basis of the phenomenological approach: we discuss here the results of birefringences in LiNbO3 crystals under the inhomogeneous mechanical strain (torsion) for various experimental configurations and the observation of optical activity under the torsional deformation in centrosymmetrical NaBi(MoO4)2 crystals. The possibility of application of the torsion-induced optical effects is also mentioned.
Raman Scattering Study of InGaAsP Quaternary Alloys Grown on InP in the Immiscible Region
Authors: Sugiura Touko , Hase Nobuyasu , Iguchi Yasuhiro , Sawaki Nobuhiko
Published: October 2002

We have studied the asymmetric broadening of the Raman spectra of In
x
Ga1-x
As
y
P1-y
grown on InP in the immiscible region using the spatial correlation model. The compositional dependence of Raman peaks are well explained by a simple model which does not account for the immiscibility. However, the broadening of the Raman line shape is greatly enhanced in the samples in the region of the immiscibility. In particular, the asymmetry of the spectral peak of the InAs-like longitudinal optical phonon is found to be enhanced in the immiscible region. This shows that the samples which include the immiscibility have been structurally changed to suppress the uniform distribution of the long wavelength phonons.
Epitaxial Growth of the GaN Film by Remote-Plasma Metalorganic Chemical Vapor Deposition
Authors: Lai Wei-Chi , Chang Chun-Yen , Yokoyama Meiso , Guo Jen-Dar , Tsang Jian-Shihn , Chan Shih-Hsiung , Bow Jong-Shing , Wei Sun-Chin , Hong Ray-Hua , Sze Simon M.
Published: October 2002

GaN films were successfully grown by the remote-plasma metalorganic chemical vapor
deposition (RPMOCVD) system. The composition of the GaN films could be tuned from
nitrogen-rich to stoichiometric growth by varying the mole flow rate of trimethylgallium
(TMGa). A hypothesis concerning the collisions between excited nitrogen and TMGa was
also brought up. The collision between excited nitrogen and TMGa influences the
characteristics of surface morphology, composition, growth rate, and growth mechanism. The
characteristics of the GaN film were optimized by changing the growth conditions. The
narrowest FWHM of the double-crystal X-ray rocking curve is about 0.2°. Under optimized
conditions, the composition of the GaN film is almost the same as that of the reference GaN
film grown by MOCVD.
Negative Thermal Quenching Curves in Photoluminescence of Solids
Authors: Shibata Hajime
Published: October 2002

We have derived an analytical formula for the temperature dependence of the photoluminescence (PL) intensity when the “negative” thermal quenching phenomenon is observed. The formula was examined using available experimental data for GaAs and ZnS, and the agreement of the results was quite good. It was confirmed quantitatively that the principal mechanism of negative thermal quenching is the thermal excitation of electrons to the initial state of the PL transition from the eigenstates with smaller energy eigenvalues. In addition, it was revealed that the real activation energy for the nonradiative recombination processes is given by ε+E
′ when the negative thermal quenching phenomenon is observed, where ε is the activation energy estimated simply from the apparent slope in the experimental data, and E
′ is the activation energy for the negative thermal quenching phenomenon.
Uniformity of the High Electron Mobility Transistors and Resonant Tunneling Diodes Integrated on an InP Substrate Using an Epitaxial Structure Grown by Molecular Beam Epitaxy and Metalorganic Chemical Vapor Deposition
Authors: Koichi Maezawa Koichi Maezawa , Jiro Osaka Jiro Osaka , Haruki Yokoyama Haruki Yokoyama , Masafumi Yamamoto Masafumi Yamamoto
Published: October 2002

We integrated InAlAs/InGaAs high electron mobility transistors (HEMTs) and InGaAs/AlAs/InAs resonant tunneling diodes (RTDs) on an InP substrate. To obtain uniform threshold voltages, we inserted an InP etch-stop layer into the InAlAs barrier layer of the HEMT. We used metalorganic chemical vapor deposition (MOCVD) to grow the HEMT layers and molecular beam epitaxy (MBE) to grow the RTD layers. This is because InP layers can be easily grown using MOCVD, but MBE is a superior technique for growing highly strained resonant tunneling structures consisting of AlAs/InGaAs/InAs.
The average threshold voltage and transconductance of HEMTs with 0.7-µm-long gates fabricated on a 2 inch wafer were -0.44 V and 843 mS/mm, respectively, and the standard deviations of these values were only 30 mV and 15.7 mS/mm, respectively. Despite the regrowth procedure used to fabricate the RTDs, they had good current–voltage (I–V) characteristics and the standard deviation of the peak current was only 3%.
Optical Nonlinearities of Bis(4-dimethylaminodithiobenzil)-nickel Solution in the Nanosecond Regime
Authors: Li Hongpu , Ogusu Kazuhiko
Published: October 2002

Nonlinear absorption and nonlinear refraction of the saturable absorber
BDN (bis(4-dimethylaminodithiobenzil)-nickel) in a nitrobenzene solution are
studied using a nonlinear transmission method and z-scan methods, respectively, under irradiation with 23 ns laser pulses at 1.047 µm. The z-scan experiment shows that, in contrast to the previous work by Zhu and Garmire
[IEEE J. Quantum Electron. 19 (1983) 1495], the main origin of the intensity-dependent refractive index change in the dye solution is the thermal effect even in the nanosecond regime. The buildup of the thermal lens is attributed to the photoacoustic effect and its rise time is proportional to the
beam spot size. For a tightly focused beam, the rise time can be as fast as
about ten nanoseconds. The fall time of the thermal lens is determined by
thermal diffusion and is generally on the order of milliseconds. Moreover,
nanosecond optical limiting and pulse narrowing have been demonstrated using strong self-defocusing induced by the photoacoustic effect.
Waveguiding Epitaxial Potassium Lithium Niobate Single-Crystal Films Deposited by Metalorganic Chemical Vapor Deposition
Authors: Chikuma Kiyofumi , Onoe Atsushi , Yoshida Ayako
Published: October 2002

Epitaxial potassium lithium niobate (KLN) single-crystal films were deposited on potassium lithium tantalate (KLT) single-crystal substrates by low-pressure metalorganic chemical vapor deposition (MOCVD). Pentaethoxyniobium [Nb(OC2H5)5] and K and Li-dipivaloylmethane [K(DPM), Li(DPM)] were used as volatile metalorganic precursors. The crystallinity of the films was investigated by X-ray diffraction measurements. Reciprocal space mapping indicated that good epitaxial growth had been achieved. The film surface was smooth enough to act as a waveguide. Several guided modes were observed for both TE and TM waves by the prism coupler method. Refractive indices of the films for various wavelengths were determined and the phase matching property of the waveguide is discussed. The propagation loss, estimated by the cut-back method, was found to be 0.5 dB/cm at a wavelength of 633 nm.
Structural and Electrical Characteristics of Ba(Zr0.12Ti0.88)O3 Thin Films Deposited on LaNiO3 Electrode by RF Magnetron Sputtering
Authors: Shy Hsiou-Jeng , Wu Tai-Bor
Published: October 2002

Sputter-deposited LaNiO3 (LNO) was used as a bottom electrode for the deposition
of 50-nm-thick Ba(Zr0.12Ti0.88)O3 (BZT) thin films on Pt/Ti/SiO2/Si substrates by rf
magnetron sputtering. Highly intense and (100)-oriented perovskite films of BZT were
grown on a (100)-textured LaNiO3 electrode by rf magnetron sputtering at
temperatures varying from 300 to 550°C in an atmosphere of Ar/O2=50/50, or in
Ar/O2 atmosphere varying from 50/50 to 90/10 at 400°C. The BZT films had a very
smooth surface and an interface coherently bonded to the LNO electrode. X-ray diffraction (XRD)
revealed that the crystallinity and lattice constant of the BZT films changed with
deposition condition. With improvement in film crystallinity, the dielectric constant of
the BZT films increased. A value of k=210–250 was obtained for films deposited at
400–450°C in the Ar/O2=50/50 atmosphere, and more importantly, a highly insulative
characteristic of low leakage current of ∼10-9 A/cm2 with a high onset field of
∼1 MV/cm was achieved for the BZT capacitors. The leakage current was also
significantly affected by preparation conditions of the top and bottom electrodes of the
BZT capacitors.
Thermal and Optical Stabilities of Photoisomerizable Polyimide Layers for Nematic Liquid Crystal Alignments
Authors: Byoungchoo Park Byoungchoo Park , Youngyi Jung Youngyi Jung , Hyun-Hee Choi Hyun-Hee Choi , Ha-Keun Hwang Ha-Keun Hwang , Youngkyoo Kim Youngkyoo Kim , Sooman Lee Sooman Lee , Sei-Hum Jang Sei-Hum Jang , Masa-aki Kakimoto Masa-aki Kakimoto , Hideo Takezoe Hideo Takezoe
Published: October 2002

We have investigated the thermal and optical stabilities of the
photoalignment layers for nematic liquid crystals (LCs).
For the photoalignment layers, three kinds of photoisomerizable polymer
systems were studied; a polyamic acid doped with azobenzene molecules,
a side-chain-substituted polyamic acid with azobenzene units, and a
main-chain-substituted polyamic acid with azobenzene units. Photoinduced
anisotropy was produced by illumination with linearly polarized near-UV light
from a mercury lamp, and evaluated by measuring polarized UV absorption
spectra and optical
birefringence. The nematic LC-alignment properties were investigated using the
photoalignment layers processed under various thermal and optical conditions. It
was observed that the main-chain polyimide system exhibited good
unidirectional LC alignment and excellent thermal (300°C for 1 h) and
optical stabilities. Moreover, we suggest a new procedure, in which the
photoillumination process is carried out before the thermal imidization process,
to achieve a stable photoalignment layer.
Ru Electrode Deposited by Sputtering in Ar/O2 Mixture Ambient
Authors: Aoyama Tomonori , Murakoshi Atsushi , Imai Keitaro
Published: October 2002

Ru films are fabricated by dc magnetron sputtering in an Ar/O2 ambient, as the bottom
electrodes of Ba0.5Sr0.5TiO3 thin film capacitors. The Ru films deposited on Si in an Ar/O2
mixture ambient show low resistivity and low film stress and do not form Ru2Si3 following
thermal processing even at 700°C. It becomes clear that there exist very thin amorphous and
crystalline layers composed of Ru, Si and O between the Ru films and Si in the case of Ru
films deposited in an Ar/O2 ambient. A low contact resistance at the Ru/n+-Si interface is
obtained after annealing at 700°C. An effective SiO2 film thickness of 0.42 nm is obtained
for an actual Ba0.5Sr0.5TiO3 film thickness of 42 nm with a leakage current of less than
1×10-8 A/cm2 in the range between -1.5 V and +1.8 V for a Ru/Ba0.5Sr0.5TiO3/Ru/n+-Si
capacitor without a barrier metal layer.
Evaluation of Free Energy on Si(110) Surface
Authors: Yamamoto Youiti
Published: October 2002

Scanning tunneling microscopy (STM) and reflection high-energy
electron diffraction (RHEED) are used to estimate the generation
probability of the (17, 15, 1)2×1 step and the domain size of the “16×2”
structure at room temperature. From both studies, the area size of the “16×2”
structure along the <111> direction is deduced to be about 50 nm.
Therefore, the generation probability of the (17, 15, 1)2×1 step is estimated
to be 0.1–0.2. From the estimated values, the free energy increase per unit
length of the (17, 15, 1)2×1 step δF is estimated to about 1.8×10-13 (J/m).
Transition of Particle Growth Region in SiH4 RF Discharges
Authors: Kawasaki Hiroharu , Sakamoto Kazutaka , Maeda Shinichi , Fukuzawa Tsuyoshi , Shiratani Masaharu , Watanabe Yukio
Published: October 2002

The growth region of particles in SiH4 RF discharges is investigated with the parameters of pressure, SiH4 concentration and RF power. When the diffusion time τD of SiH2 radicals
(key species for fast particle nucleation) through their production region is longer than their reaction time τR with SiH4 and sufficient SiH2 radicals are supplied, particles grow at a
high growth rate of \gtrsim10's nm/s localized only around the plasma/sheath (P/S) boundary near the RF electrode where the radicals are produced. Under this condition, neutral clusters (resulting from the polymerization reactions) react with
each other many times before they diffuse out of the radical production region. Since the diffusion time of clusters through the radical production region increases with cluster size, large clusters tend to
be localized there and grow further to sizes on the order of nm. With τR>τD and/or insufficient supply of SiH2 radicals, particles grow at a low rate of 1 nm/s and exist in the plasma bulk as well as around the P/S boundary. Such low growth rates suggest that negatively charged clusters are indispensable in order for particles to grow to above several nm in size.
Determination of Collisional Quenching Rate for the 4D3/2 State in SrII
Authors: Hirano Iku , Yoda Jun , Hong Feng-Lei , Okumura Kenichiro , Onae Atsushi
Published: October 2002

Sr+ ions were confined in a rf trap with He buffer gas. Weak fluorescence from
Sr+ ions was detected using a frequency-doubled semiconductor laser, a CW fiber laser
(pump-back light) and the photon counting method. Increase in fluorescence using
the pump-back laser enabled the determination of collisional quenching rates for the
4d2D3/2 state. A collisonal quenching rate of 6400(s-1Pa-1) was obtained. This result
reveals that collisional quenching rate for the metastable state can be determined
by using CW lasers instead of pulse lasers.
Determination of the Anisotropic Optical Constant of Evaporated Polydiacetylene-C4UC4 Films at 632.8 nm
Authors: Hasegawa Tatsuo , Okamoto Toshihiro , Haraguchi Masanobu , Fukui Masuo , Koda Takao , Takeda Kenji
Published: October 2002

We have proposed a simple reflection method to evaluate the optical constants and optical thicknesses of various films. The optical constants and thicknesses of alkyl-urethane-substituted polydiacetylene (PDA-C4UC4) films on a BK-7 glass prism have been measured using the reflection method proposed in this paper. Unoriented blue-form PDAs have an optically anisotropic nature and their optical constants have been estimated in the tangential direction and in the direction normal to the film surface. Our reflection method also provides information on the polymerization state.
A Solid-State Electrochemical Device Using Poly(pyrrole) as Micro-actuator
Authors: Yamada Katsumi , Kume Yuichiro , Tabe Hiroshi
Published: October 2002

A solid-state microactuator was studied using volume change due to
redox reaction of poly(pyrrole) film. Pyrrole was electropolymerized on a
comb-shaped microelectrode array, and the poly(pyrrole) film was covered
by a solid polymer electrolyte, polyethylene glycol. The volume change
of the poly(pyrrole) film by electrochemical polarization was measured
using a laser displacement sensor, and the mechanism of the volume
change was discussed.
Influence of Low Dielectric SiOF Film on Metal Oxide Semiconductor Field Effect Transistor Characteristics and Its Impact on Circuit Performance
Authors: Ida Jiro , Ohtomo Atsushi , Yoshimaru Masashi
Published: October 2002

A low dielectric fluorine-doped silicon oxide (SiOF) film, which was produced by adding C2F6 to the conventional chemical vapor deposited oxide, was applied to a 0.35 µm complementary metal oxide semiconductor (CMOS) and its influence on metal oxide semiconductor field effect transistor characteristics was analyzed. A shift of the transconductance was observed when the SiOF film was used as an intermediate dielectric and the Si3N4 film as the dielectric on the metal. An improvement in speed of 13% due to the SiOF film was experimentally confirmed under the condition where the transconductance does not show a shift. Using circuit simulations, the necessity for such low dielectric films as the SiOF film, on the scaling trend in the improvement of circuit performance, was clearly shown and was also emphasized from the point of view of power reduction. It was revealed that circuit speed and power consumption of 0.35 µm CMOS were degraded if the SiOF film was not used, because the improvement of the transistor performance did not overcome the increase in interconnect capacitance due to the increase in the adjacent interconnect capacitance component.
New Ar-Plasma Cleaning Process for Reduction of Al/TiSi2 Contact Resistance
Authors: Tsuno Morikazu , Yokoyama Shin , Shibahara Kentaro
Published: October 2002

RF-Ar-plasma cleaning lowers Al/TiSi2 contact resistivity by 70% in comparison to conventional buffered-HF (BHF) cleaning. This improvement is due to effective removal of contaminants at the bottom of contact holes. Application of the Ar-plasma treatment to the Si surface before silicidation leads to a decrease in contact resistance down to 25 Ω for 0.3-µm-diameter contact holes. The decrease is believed to be due to the fact that the effective barrier height between TiSi2 and n+-Si is reduced by defects induced by Ar cleaning.
Subquarter-micrometer Dual Gate Complementary Metal Oxide Semiconductor Field Effect Transistor with Ultrathin Gate Oxide of 2 nm
Authors: Shimizu Masahiro , Kuroi Takashi , Inuishi Masahide , Arima Hideaki , Abe Haruhiko , Hamaguchi Chihiro
Published: October 2002

The high performance of 0.25 µm dual gate complementary metal oxide semiconductor
with an ultrathin gate oxide of 2 nm is demonstrated for low-voltage logic applications.
Boron penetration can be effectively suppressed by the nitrogen implantation technique, even
if the gate oxide film is reduced to 2 nm. It is confirmed that N-channel and P-channel metal
oxide semiconductor field effect transistors (MOSFETs) with high current drivability can be
realized by the thin gate oxide, although the transconductance is not inversely proportional to
the gate oxide thickness due to the increase in the effect of the inversion capacitance and the
gate depletion. The inverter delay time with the aluminum interconnect load is markedly
improved by the highly drivable MOSFETs with thin gate oxide, especially at low-voltage
operation. Furthermore, hot carrier degradation of N-channel MOSFETs can be suppressed
by reducing the gate oxide thickness. However, it was found that the hot carrier degradation
of P-channel MOSFETs is enhanced in the thin gate oxide region under channel hot hole
injection.
Size Fluctuation of 50 nm Periodic GaInAsP/InP Wire Structure by Electron Beam Lithography and Wet Chemical Etching
Authors: Takashi Kojima Takashi Kojima , Xue-Ying Jia Xue-Ying Jia , Yoshinori Hayafune Yoshinori Hayafune , Shigeo Tamura Shigeo Tamura , Masahiro Watanabe Masahiro Watanabe , Shigehisa Arai Shigehisa Arai
Published: October 2002

We investigated a size fluctuation of 50 nm
periodic wire pattern of GaInAsP/InP structure with a typical wire width of around 30 nm, which was
fabricated by an electron beam lithography followed by wet chemical etching.
The size fluctuation of the ZEP-520 positive
resist pattern was reduced from 2.7 nm to 1.4 nm by
using a corrected dose profile taking the proximity effect into account, and that of the quantum-wire
structure after wet etching was reduced from 3.8 nm to 2.9 nm.
Design Considerations of GaInNAs-GaAs Quantum Wells: Effects of Indium and Nitrogen Mole Fractions
Authors: Kim Chang-Kyu , Miyamoto Tomoyuki , Lee Yong-Hee
Published: October 2002

The influences of In and N compositions on the optical gain characteristics of a GaInNAs-GaAs single quantum well are studied theoretically for the first time. When compared with GaInAs, GaInNAs shows a higher optical gain and a longer emission wavelength, under the condition of identical strain. For a given operating wavelength, the higher-In GaInNAs quantum well exhibits a larger optical gain and a smaller carrier leakage than the higher-N GaInNAs quantum well. For example, more than a two-fold improvement in threshold current is expected from the higher-In Ga0.6In0.4N0.01As0.99 quantum well laser than the higher-N Ga0.75In0.25N0.02As0.98 quantum well laser operating at 1.3 µm.
Development of a Model for Chirped-Pulse Amplification of Sub-20 fs Laser Pulses
Authors: Matsuoka Shinichi , Yamakawa Koichi
Published: October 2002

We have developed a simple model for ultrabroadband and ultrashort pulse amplification.
We provide detailed calculations of the effects that govern chirped-pulse amplification including
regenerative pulse shaping, gain narrowing and gain saturation in Ti:sapphire laser amplifiers.
Thin solid etalons are used to control both gain narrowing and gain saturation during
amplification. This model has been used to design an optimized Ti: sapphire amplifier system
for efficiently producing pulses of sub-20-fs duration as the peak power of 100 TW is
approached.
A Fractal Analysis on Domain Related Electric Field Induced Acoustic Emission in Ferroelectric Ceramics
Authors: Aburatani Hideaki , Witham John P. , Uchino Kenji
Published: October 2002

The electric field induced acoustic emission (AE) in ferroelectric ceramics under bipolar electric fields has been studied. From the AE event rate and the AE signal amplitude distribution, it is assumed that there are two origins of the field induced AE in the ferroelectric ceramics: domain reorientation related deformation and piezoelectric deformation without domain reorientation. The fractal dimension (m) in the field induced AE signal amplitude distribution of the ferroelectric ceramic is found to be m=1 for the domain reorientation related deformation. The fractal dimension of m=2.8 is observed for the piezoelectric deformation unrelated to domain reorientation after domain reorientation is completed. It is shown that the fractal dimension of the AE caused by the domain reorientation related deformation is lower than that of the AE generated by the piezoelectric deformation unrelated to domain reorientation at high electric fields.
Microscopy of SiC Layers Grown by C60 Deposition on Si (100)
Authors: Scholz Roland , Gösele Ulrich , Volz Kerstin , Rauschenbach Bernd
Published: October 2002

Silicon carbide layers grown by C60 deposition on silicon (100) substrates at temperatures between 700°C and 870°C
were investigated by optical microscopy (OM) as well as by scanning and transmission electron microscopy (SEM and
TEM). The formation of extended cavities in the substrate surfaces, below the growing SiC layers, was observed. These
cavities start to develop at the very beginning of SiC nucleation. The SiC layers bridging the cavities consist of
columnar grains and contain open channels in between the grains. The epitaxial-oriented cubic fractions in the SiC
layers increase with the elevation of the substrate temperature applied during C60 deposition.
Epitaxial Growth of TiC (002) on Si (001) by Reactive Magnetron Sputtering at Low Temperatures
Authors: Sheu Wei-Hwa , Wu Shinn-Tyan
Published: October 2002

Epitaxial growth of TiC (100 nm) on Si (001) has been thoroughly
investigated by X-ray pole figure analysis. Growth is achieved by
reactive magnetron sputtering using metal target in a mixture of argon
and acetylene. The acetylene partial pressure of is kept low at 2.6×10-5 Torr and the substrate temperature is higher than 500°C. This
process is strikingly similar to the epitaxial growth of TiN, which
suggests that the diffusion of metal atoms to kink sites is the dominant
factor during epitaxial growth; lattice mismatch does not determine
epitaxial growth.
Studies on the Surface Morphology and Orientation of CeO2 Films Deposited by Pulsed Laser Ablation
Authors: Develos Katherine D. , Kusunoki Masanobu , Ohshima Shigetoshi
Published: October 2002

We studied the surface morphology and orientation of CeO2 films grown by pulsed laser
ablation (PLA) on r-cut (1102) Al2O3 substrates and evaluated the effects of predeposition
annealing conditions of Al2O3 and film thickness of CeO2. The annealing of Al2O3 substrates
improves the smoothness of the surface and performing this in high vacuum leads to better
crystallinity and orientation of deposited CeO2 films compared to those annealed in oxygen.
A critical value of the film thickness was found beyond which the surface roughness increases
abruptly. Atomic force microscopy (AFM) study showed that the surface of CeO2 films is
characterized by a mazelike pattern. Increasing the film thickness leads to the formation of
larger islands which cause the increase in the surface roughness of the films. The areal
density and height of these islands increased with film thickness.
Atomic Force Microscope Studies on Domain Dynamics in Phosphate Substituted Triglycine Sulfate Single Crystals: Evidence for the Domain Boundary Motion towards Negative Region and Holes Formation at the Domain Boundary
Authors: Balakumar Subramanian , Xu Jian Bin , Arunmozhi Gnanasundaram , Jayavel Ramasamy , Nakatani Noriyuki , Yamazaki Toshinari
Published: October 2002

Domain dynamics in the (010) plane of phosphate substituted triglycine sulfate (TGSP) crystals with time are investigated by atomic force microscopy. The domain boundary migration from positive to negative side and the simultaneous formation of holes are imaged for the first time. The holes are transformed from needle to round shape with time. The domain boundary movement occurs in order to reduce the total energy, not only the surface but also bulk energy. However, the formation of holes at the boundary may occur because of insufficient supply of molecules from the surroundings and surface charge neutralization due to polarization reversal in the region.
Characterization of RF-Enhanced DC Sputtering to Deposit Tin-Doped Indium Oxide Thin Films
Authors: Futagami Toshiro , Shigesato Yuzo , Yasui Itaru
Published: October 2002

The effect of RF (13.56 MHz) enhancement in a DC magnetron sputtering process was studied using a one-turn coil above a tin-doped indium oxide (ITO) target. The minimum operating pressure or the minimum operating voltage was reduced to less than one-half by the assistance of RF plasma. The processing plasma was characterized quantitatively in terms of plasma potential (V
p), floating potential (V
f), electron density (N
e), and electron temperature (T
e) using a Langmuir probe. The probe measurements were also verified using optical emission spectroscopy. V
p and V
f increased with increasing RF coil power (P
c) and were strongly dependent on the target voltage. N
e increased from 3.7×108 /cm3 at P
c=10 W to 1.3×109 /cm3 at P
c=50 W at a target voltage of -200 V. At the target voltage of -300 V, N
e increased slightly from 1.0×109 /cm3 at P
c=10 W to 1.2×109 /cm3 at P
c=50 W, whereas T
e showed almost no dependence on the RF coil power. T
e was strongly dependent on the target voltage, being significantly higher at -200 V as compared to -300 V. The crystallinity of the deposited ITO films was found to increase with increasing RF coil power.
Electrical Property of Poly(3-octyloxythiophene) and Its Gas Sensor Application
Authors: Kawai Tsuyoshi , Kojima Shin-ichi , Tanaka Fumiaki , Yoshino Katsumi
Published: October 2002

Electrical and optical properties of poly(3-octyloxythiophene), ROPT-8, and its unique sensor
characteristics have been studied. Due to the high energy of the valence band top leading to the
electro-donating characteristics of the alkoxy group, ROPT-8 exhibits stable electrical resistance in
the doped state, which allows it to be used as a sensor material. The resistance changed reversibly
upon exposure to various organic flavor gases and a linear response was observed in relation to the
gas concentration. The selectivity and control of sensitivity to organic gas molecules have also been studied.
Nonhomogeneous Pattern Formation in the Dissolution Processes of Novolak-Diazonaphthoquinone Resists
Authors: Kanzaki Kenichi , Ohfuji Takeshi , Sasago Masaru , Tagawa Seiichi
Published: October 2002

The development mechanisms of irradiated novolak-diazonaphthoquinone resists have
been studied on the basis of the atomic force microscopy (AFM) data of resist surface images. The
characteristic surfaces with large holes or island structures, that is, nonhomogeneous surfaces, have
been observed at the exposure doses near the beginning of the film thickness reduction. The
changes in the size of holes and island structures roughly correspond to the changes of cluster size
estimated by percolation theory. From the dissolution pattern changes which depend on exposure
dose, it is considered that an adequate exposure dose is indispensable for high-precision patterns and
such an exposure dose determines the sensitivity of positive-type resists.
Superconducting Radiation Detectors and Their Future Perspectives
Authors: Hans Kraus Hans Kraus
Published: October 2002

Cryodetectors with superconducting sensors have been actively developed and optimized during the past years. This review discusses the operating principles of the two detector concepts, superconducting tunnel junctions and low-temperature bolometer or calorimeter. Progress in research with cryodetectors manifested itself by many successful device demonstrations and as a result, a shift in emphasis from pure detector optimization towards actual applications has been observed. Cryodetectors have been used for X-ray fluorescence, optical photon detection, mass spectroscopy of heavy molecules, etc. Nevertheless, there is still room for further improvement until the detectors will have actually reached their theoretical limitations.
Interfacial Properties of Silicon Structures Fabricated by Vacuum Grooved Surface Bonding Technology
Authors: S. Argunova Tatyana , V. Grekhov Igor , S. Kostina Lyudmila , V. Kudryavtzeva Tina , Gutkin Mikhail Yu. , Härtwig Jürgen , Eun-Dong Kim Eun-Dong Kim , Sang-Cheol Kim Sang-Cheol Kim , Nam-Kyun Kim Nam-Kyun Kim
Published: October 2002

The paper presents a novel modification of a direct bonding technology. A
presented innovation is aimed at fabricating void free interfaces with a low
defect density. For this purpose the bonding boundaries are manufactured as
grooved, and the bonding annealing is performed under vacuum conditions. It
has been found that the grooves act as dislocation traps. A trapped gas
escapes through the grooves which facilitates the void removal. By X-ray and
electron diffraction techniques the grooves have been observed to flatten
rapidly. The electrical properties of the grooved interfaces are as good as
those of diffusion p-n junctions.
Photoinduced Surface Deposition of Ag–Ge–S Films: Its Enhancement by Addition of Small Amount of Au
Authors: Kawaguchi Takeshi
Published: October 2002

The effect of the addition of Au on photoinduced surface
deposition (PSD) has been examined using Ag–Ge–S films with
various Ag contents. Photosensitivity of the PSD effect was
found to be enhanced by the addition of a small amount of Au
(less than 2 wt%). The enhancement was significant for the film
with a low Ag content but decreased with an increase in the Ag
content. The result can be explained by the idea that the Au
atoms incorporated in the Ag–Ge–S network may form Au clusters
which can act as nucleation centers of stable Ag nuclei in the
PSD process.
Analysis of Surface States of Gallium Arsenide Metal Semiconductor Field-Effect Transistors using Drain Current Transients under Light Illumination
Authors: Sasaki Hajime , Hayashiguchi Youichi , Yea Byeongdeok , Osaki Tomoyuki , Sugahara Kazunori , Konishi Ryosuke
Published: October 2002

Characteristics of charge trapping at surface states of gallium arsenide metal semiconductor
field-effect transistors (GaAs MESFETs) are analyzed using drain current transients under light
illumination. Accurate trap density is obtained by classifying the transient into two components:
one resulting from thermal emission and the other from light illumination. A slight decrease in
delay time is observed under infrared light illumination having the photon energy lower than the
band gap of GaAs. Pulse light illumination indicates an increase in charge trapping under the
illumination during gate-off period.
A Study on the Preparation Conditions of Single Oriented (002) Hf Film on n-(001) Si
Authors: Satoko Shinkai Satoko Shinkai , Hideto Yanagisawa Hideto Yanagisawa , Katsutaka Sasaki Katsutaka Sasaki , Yoshio Abe Yoshio Abe
Published: October 2002

We have investigated the preparation conditions of a single oriented (002) Hf film on n-(001) Si, by varying the sputtering parameters during deposition. The crystallinity and orientational plane of the prepared Hf films were evaluated by X-ray diffraction and cross-sectional transmission electron microscopy. We found that the single oriented (002) Hf film grows on the (001) Si substrate under the sputtering conditions of sputtering power above 50 W, substrate temperature of about 400°C, sputtering gas pressure below 2 mTorr and film thickness below 1000 Å, although a thin amorphous silicide layer is interposed between Si and Hf. Furthermore, it is also revealed that a (111) Al film, with excellent electromigration resistance, grows in a single oriented state on the (002) Hf film, because of the small lattice mismatch (0.8%) between (002) Hf and (111) Al two-dimensional superlattice cells.
New Method to Increase Solid Precursor Vaporization for Metalorganic Chemical Vapor Deposition
Authors: Tasaki Yuzo , Yoshizawa Shuji , Satoh Mamoru
Published: October 2002

A method for obtaining the saturated vapor of conventional alkaline-earth DPM (dipivaloylmethanato) complexes was investigated. The saturated vapor of a barium precursor was obtained using a eutectic mixture of bis[dipivaloylmethanato]barium (Ba(DPM)2) and bis[2,2,6,6-tetramethyl-3,5-octanedionato]barium (Ba(TMOD)2) as a precursor because the eutectic point of the mixture was below 200°C, where vaporization in the liquid state was possible. During the preparation of a thin film of barium oxide using Ba(DPM)2 and Ba(TMOD)2, mixed in the ratio of 4 to 1, as a mixed precursor at 200°C, the deposition rate as three times higher than compared to that obtained using Ba(DPM)2 singly as a precursor.
Electrooptical Properties of an Aligned Phase-Change Guest-Host Mode Liquid Crystal Display
Authors: Wu Jin-Jei , Lee Tzu-Yang , Chen Shu-Hsia , Kuo Chen-Lung
Published: October 2002

We have studied the electrooptical properties of an aligned phase-change guest-host
(PCGH) mode liquid crystal display. Samples with various thickness-to-natural pitch ratios d/p
0
are fabricated. For each d/p
0, we measure the phase transition fields, the ON- and OFF-state
transmittances and the response times. The phase transition fields are compared to the numerical
values calculated from theory. In addition, it is found that when d/p
0≥1.2 the d/p
0 ratio hardly
affects the transmittances but does affect the response times of the sample film. The experimental
result also demonstrates that the response times and the phase transition voltages are affected by
the rubbing condition.