bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Femtosecond Laser Induced Visible Long-Lasting Phosphorescence in Mn2+-Doped Sodium Borate Glasses
Authors: Qiu Jianrong , Kondo Yuki , Miura Kiyotaka , Mitsuyu Tsuneo , Hirao Kazuyuki
Published: October 2002

We report on the long-lasting phosphorescence phenomenon in Mn2+-doped sodium
borate glass. After scanning by a focused 800 nm femtosecond laser for 10 s, the path
traversed by the focal point of the laser in the glass emits reddish long-lasting
phosphorescence visible to the naked eye in the dark five minutes after the removal
of the activating laser. Absorption spectra of the glass showed that defect centers
were induced after laser irradiation, and the absorption due to the laser-induced
defect centers decayed with time. The long-lasting phosphorescence is considered
to be due to the thermostimulated recombination of holes and electrons at traps induced
by the laser irradiation, and energy transfer from the composite defect centers to Mn2+ ions.
Fluorescent Liquid Crystal Color Display Using a Guest–Host UV Shutter and Phosphor Layers on the Inside of the Cell
Authors: Rumiko Yamaguchi Rumiko Yamaguchi , Junya Kishida Junya Kishida , Yasuhiro Ugai Yasuhiro Ugai , Tukasa Izumi Tukasa Izumi , Susumu Sato Susumu Sato
Published: October 2002

Fluorescent liquid crystal displays (LCDs) have been demonstrated using a guest–host (GH) LC UV shutter cell. Red, green and blue inorganic phosphor lines were manufactured on a glass substrate and an indium–tin–oxide electrode was coated on a phosphor layer. The GH LC cell was composed of this substrate and the phosphor layer was inside of the cell, as well as the color filter used in the current LCD. A UV light emitting diode or a UV fluorescent lamp was used as an excitation source and the switching properties of the fluorescence intensity and their contrast ratio were measured and discussed.
Vapor Pressure and Mean Adsorption Time of Pyromellitic Dianhydride and 4,4′-Oxidianiline
Authors: Dutt Radhika , Takahashi Yoshikazu , Iijima Masayuki
Published: October 2002

Thermogravimetry (TG) measurements taken at pressures ranging from 10-1 to 10-3 Pa
are used to calculate the vapor pressure of pyromellitic dianhydride (PMDA) and 4,4′-oxidianiline
(ODA). The vapor pressure calculated for PMDA is closely agrees with to
those reported by Pethe et al.., Elshazly and Salem. For ODA, the calculated vapor
pressure fits exactly on the curve obtained by Salem. The enthalpy is also calculated. The
activation energy of desorption is found to be nearly equal to the enthalpy. The
adsorption and desorption rates for both PMDA and ODA at various substrate
temperatures are also observed. The mean adsorption time, τ calculated for ODA is
several orders of magnitude larger than that for PMDA. 1:1 doses of ODA and PMDA
therefore produce imine bonds which lead to the formation of thermally unstable films.
Three Different Forms of Hydrogen Molecules in Silicon
Authors: Kitajima Masahiro , Ishioka Kunie , Nakanoya Kimishige , Tateishi Seiji , Mori Toshiki , Fukata Naoki , Murakami Kouichi , Hishita Shun-ichi
Published: October 2002

We have studied three different H2 molecules in crystalline silicon using Raman scattering. The
vibrational line at 3601 cm-1 attributable to H2 in Td site is observed both in n-type and p-type
crystalline silicon. It is suggested from the hydrogenation-temperature dependence that the
charge states and the sites of atomic hydrogen affects the formation of this type of H2. H2 in
platelet observed at 4158 cm-1 decreased in its intensity in Si+-implanted silicon. A new
vibrational line is detected at 3822 cm-1, and attributed to H2 trapped by hydrogen-related
defects such as multivacancies produced by ion implantation.
Piezoelectric Properties and Acoustic Wave Detection of Pb(Zr0.52Ti0.48)O3 Thin Films for Microelectromechanical Systems Sensor
Authors: Cho Chae-Ryong , Francis Lorraine F. , Jang Min-Su
Published: October 2002

Ferroelectric Pb(Zr0.52Ti0.48)O3 thin films were deposited on Pt/TiO2/SiO2/Si substrates by the sol-gel technique. It was found that above 550°C the film transforms completely to the perovskite and
forms a typical ferroelectric polarization-electric field (P-E) hysteresis loop. The effective d
33 of
piezoelectric PZT films was measured using a Michelson interferometer. The piezoelectric hysteresis
loop was measured according to dc bias voltage and the maximum piezoelectric coefficient for the
0.48-µm-thick poled film was about 130 pm/V at -3 V. Acoustic emission (AE) wave propagation
through PZT films connected to a charge amplifier was observed. These properties suggested that
PZT film is a very promising material for integrated AE sensor applications, with promise for
improved reliability.
Ultraviolet Photoconductive Hydrogenated Amorphous and Microcrystalline GaN
Authors: Yagi Shigeru
Published: October 2002

Hydrogenated amorphous and microcrystalline GaN films
are grown by remote-plasma metalorganic chemical vapor
deposition at a substrate temperature below 300°C. These films
have a stoichiometric composition with 17 to 30 at% hydrogen.
The films on aluminum exhibit a fast ultraviolet (UV)
photoresponse with a photocurrent to dark current ratio of 104.
The normalized photoconductivity, ηµτ of the film with E
opt of
3.2 eV is of the order of 10-6 cm2·V-1. Photodegradation effects
have never been observed even after 5 h of irradiation with
intense UV light of 500 mW/cm2.
Preparation of Organic Microcrystals Using Supercritical Fluid Crystallization Method
Authors: Komai Yuko , Kasai Hitoshi , Hirakoso Hideyuki , Hakuta Yukiya , Katagi Hideyuki , Okada Shuji , Oikawa Hidetoshi , Adschiri Tadafumi , Inomata Hiroshi , Arai Kunio , Nakanishi Hachiro
Published: October 2002

We propose that the supercritical fluid crystallization (SCFC) method is one of the most promising techniques for preparing organic microcrystals. In the case of titanylphthalocyanine (TiOPc) and diacetylenes, the size and forms of the resulting microcrystals could be controlled by changing SCFC
conditions. In particular, the SCFC method for the microcrystallizaton of phthalocyanines is expected to be useful, replacing the previous acid-pasting method.
Optically Patternable Polymer Light-Emitting Device
Authors: Kazuya Tada Kazuya Tada , Mitsuyoshi Onoda Mitsuyoshi Onoda , Hiroshi Nakayama Hiroshi Nakayama
Published: October 2002

Optically patternable polymer light-emitting devices with an indium-tin-oxide/poly(2-methoxy-5-dodecyloxy-p-phenylene vinylene)/semitransparent-Al structure are fabricated and characterized. When the optical transmittance of the Al electrode is about 30% at a 500 nm wavelength, the emission from the device is rapidly reduced by photoirradiation in air, and the emission is completely suppressed after irradiation for 5 min. Considerable bleaching of the optical absorption of the polymer film of the devices due to photoirradiation is also observed. These effects originate from photooxidation of the polymer by the atmospheric oxygen passing through the semitransparent-Al electrode. It is also shown that these effects are considerably moderated by using a thicker Al electrode, indicating the importance of the Al electrode thickness on the patternability of the emission.
Bending Electrostriction in Polyurethanes Containing Ions as Contaminants or Additives
Authors: Watanabe Masashi , Kato Takahiro , Suzuki Makoto , Amaike Yoichi , Hirai Toshihiro
Published: October 2002

We demonstrated that the bending electrostriction in polyurethane films is controlled by
the ions contained as contaminants or additives. The sample film used in this investigation was
composed of a segmented polyester-polyurethane and was coated with a thin gold electrode on
each surface by ion-sputtering. Although the application of an electric field (2 MV/m) can
caused bending deformation of the film, removal of the ionic contaminants from the
polyurethane by electrodialysis reduced the degree of deformation. On the other hand, the
addition of a small amount of lithium bromide changed the bending direction.
Precise Velocity Measurements for Thin Specimens by Line-Focus-Beam Acoustic Microscopy
Authors: Jun-ichi Kushibiki Jun-ichi Kushibiki , Yuji Ohashi Yuji Ohashi , Mototaka Arakawa Mototaka Arakawa
Published: October 2002

When line-focus-beam acoustic microscopy is applied to thin specimens, waves reflected from the back surface of the specimen cause a serious problem in measurement accuracy of measured leaky surface acoustic wave (LSAW) velocities. Experimental results show that the velocities vary not only with the employed ultrasonic frequency but also with the specimen thickness. A method of eliminating that influence using the moving average of the frequency dependence of LSAW velocities is proposed and demonstrated for a Z-cut 5-mol% MgO-doped LiNbO3 wafer specimen about 380-µm thick.
Visible Electroluminescence from Nanocrystalline Silicon Embedded in Single-Crystalline CaF 2/Si(111) with Rapid Thermal Anneal
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 with molecular beam epitaxy from Si and partially ionized epitaxy for CaF2, followed by rapid thermal annealing (RTA) in N2 ambient.
Visible EL was observed at room temperature in the dark with the naked eye, from the whole area of the transparent electrode for current injection.
Uniformity and intensity of luminescence was drastically improved by RTA in N2 ambient.
A Two-Pass Excimer Laser Annealing Process to Control Amorphous Silicon Crystallization
Authors: Sala Luigi Mariucci
Published: October 2002

A new approach to control the lateral-growth mechanism of polycrystalline silicon films through appropriate spatial modulation of the absorbed laser energy and with a two-pass excimer laser annealing process is presented. In the first pass, spatial modulation of the light intensity has been achieved by irradiating the precursor amorphous silicon films through a patterned mask in contact with the sample, triggering the lateral growth of grain in excess of 1 µm.
During the second pass of the process, the film is reirradiated without the mask and the laterally grown grains can be used as seeds and can be propagated to crystallize the film uniformly. With optimized mask patterns the sample area can be fully covered with laterally grown grains.
A Novel Selective Growth Process Using Oxidized InAlAs Mask for Fabricating Photonic Devices and Photonic Integrated Circuits
Authors: Tsuji Masayoshi , Sasaki Tatsuya , Ishikawa Shin
Published: October 2002

We have proposed and realized a novel selective growth technique using an oxidized In0.52Al0.48As
mask. An InAlAs layer is selectively grown on top of a double hetero structure and then oxidized
by conventional wet thermal method. Another oxidation process with HNO3 solution is also
demonstrated. Using oxidized masks, selective growth to form a buried hetero-structure was
achieved for the first time. This simple technique, which does not require semiconductor etching,
will reduce the cost of fabricating photonic devices and photonic integrated circuits for
wavelength-division-multiplexing systems.
Detailed Structure of the Afterglow of Radio-Frequency Chlorine Discharge
Authors: Kenichi Nanbu Kenichi Nanbu , Takeo Nakagome Takeo Nakagome , Junichi Kageyama Junichi Kageyama
Published: October 2002

The potential, ion density, electron density, and the rates of excitation, attachment, and ionization in the afterglow of radio-frequency chlorine discharge are examined using the particle-in-cell/Monte Carlo method. The gas pressure is 50 mTorr and the amplitude of rf voltage is 250 V before the power is turned off. The electron loss mechanism changes near time t=3 µs. For t<3 µs, the loss is caused by the escape of fast electrons to the electrodes; for t>3 µs, the loss is caused by dissociative attachment of slow electrons.
Conductive Self-Assembled Meso-Structured Silica Films Synthesized by Ferrocenyl Surfactant
Authors: Zhou Haoshen , Honma Itaru
Published: October 2002

Organic molecules self-assembled into high-ordered meso-structured architectures have
attracted increasing attention because they provide a rich source for scientific research and
technological applications. We first report the conductive oriented silica meso-structure film
synthesized by ferrocenyl surfactant templating using a spin-coating method. The X-ray
diffraction pattern of the film shows that the phase is lamellar. The electronic conductivity
properties of the film are also observed.
Tunable Optical Stop Band and Reflection Peak in Synthetic Opal Infiltrated with Liquid Crystal and Conducting Polymer as Photonic Crystal
Authors: Katsumi Yoshino Katsumi Yoshino , Shigenori Satoh Shigenori Satoh , Yuki Shimoda Yuki Shimoda , Yoshiaki Kawagishi Yoshiaki Kawagishi , Keizo Nakayama Keizo Nakayama , Masanori Ozaki Masanori Ozaki
Published: October 2002

The optical stop band in the transmission spectra and the peak in the reflection spectra of opals with a three-dimensional periodic structure shift drastically upon infiltration with organic materials such as liquids, liquid crystals and conducting polymers. In these infiltrated opals, the stop band and reflection peak have been confirmed to be tunable by adjusting various conditions such as temperature and applied voltage.
Superior Pinch-Off Characteristics at 400°C in AlGaN/GaN Heterostructure Field Effect Transistors
Authors: Maeda Narihiko , Saitoh Tadashi , Tsubaki Kotaro , Nishida Toshio , Kobayashi Naoki
Published: October 2002

AlGaN/GaN field effect transistors have been fabricated on SiC(0001) substrates,
and the I–V characteristics in the devices have been examined from room
temperature to 400°C. In addition to excellent current saturation characteristics,
sufficient pinch-off characteristics have been obtained up to a temperature of 400°C
for the first time, as the result of reduced crystal defects and reduced etching damage
in the devices. The temperature dependence of the transconductance has been also
examined. The degradation rate in the transconductance has been proved to be low
above 300°C: the transconductance degraded by only 8% for a temperature increase
from 350 to 400°C. Sufficient pinch-off characteristics and a relatively low
degradation rate in the transconductance ensure the practical use of the devices at
high temperatures.
1.21 µm Continuous-Wave Operation of Highly Strained GaInAs Quantum Well Lasers on GaAs Substrates
Authors: Sato Shunichi , Satoh Shiro
Published: October 2002

Highly strained GaInAs quantum well lasers emitting at 1.21 µm are
fabricated on GaAs substrates. Room-temperature continuous-wave operation with a low
threshold current density of 360 A/cm2 is achieved. 1.3 µm GaInNAs/GaAs lasers can be fabricated at a low nitrogen content of 0.5%.
Transient Enhanced Diffusion and Deactivation of High-Dose Implanted Arsenic in Silicon
Authors: Uematsu Masashi
Published: October 2002

We have simulated the transient enhanced diffusion (TED) of
high-concentration arsenic (As) in silicon during post-implantation
annealing. A unified simulation was done, based on models for As
diffusion, for TED by self-interstitial clusters, and for end-of-range
(EOR) defects. We have taken into account As complex formation and As
precipitation, which cause the As deactivation. We have satisfactorily
fitted As depth profiles at high doses (1–5×1015 cm-2) in a wide range of
annealing conditions (750–1000°C). The As complex formation plays an
important role in determining the diffusion profiles through the
self-interstitial emission upon the formation at lower temperatures and
through As deactivation at higher temperatures. The simulation results
suggest that boron (B) segregation toward the As tail regions is associated
with self-interstitial distributions determined by EOR defects and As
profiles.
High-Mobility AlGaN/GaN Heterostructures Grown on Sapphire by Metal-Organic Chemical Vapor Deposition
Authors: Zhao Guang Yuan , Ishikawa Hiroyasu , Egawa Takashi , Jimbo Takashi , Umeno Masayoshi
Published: October 2002

High-quality AlGaN/GaN heterostructures were grown on sapphire
by metal-organic chemical vapor deposition (MOCVD). The factors
limiting electron mobility were also investigated using atomic force
microscopy, photoluminescence and capacitance–voltage
measurements. An unintentionally doped Al0.11Ga0.89N/GaN
heterostructure showed two-dimensional electron gas (2DEG)
mobilities of 12000 and 9400 cm2/V s at 9 and 77 K,
respectively, which are higher than the previously reported values
for the same structure grown on either SiC or sapphire by MOCVD. In
addition, we found that the 2DEG mobility can be enhanced by
increasing the AlGaN layer thickness.
Crystallization of Amorphous GeSe2 Semiconductor by Isothermal Annealing without Light Radiation
Authors: Kentaro Sakai Kentaro Sakai , Kenji Yoshino Kenji Yoshino , Atsuhiko Fukuyama Atsuhiko Fukuyama , Hirosumi Yokoyama Hirosumi Yokoyama , Tetsuo Ikari Tetsuo Ikari , Kouji Maeda Kouji Maeda
Published: October 2002

The thermal-induced crystallization process of melt-quenched amorphous GeSe2 was studied. The low-temperature (LT) form, LT-GeSe2 and the high-temperature (HT) form, HT-GeSe2 were observed with Raman spectroscopy, differential scanning calorimetry (DSC) and an X-ray diffractometer. We observed the X-ray diffraction pattern of LT-GeSe2 and identified the reflection index. The crystal parameters resembled those of LT-GeS2 crystal. The growth conditions for crystallization of LT-GeSe2 and HT-GeSe2 were clarified from the time-temperature-transformation diagram. It was found that amorphous GeSe2 crystallizes at first into LT-GeSe2 and then LT-GeSe2 changes into HT-GeSe2. The activation energy (E
a)) from amorphous GeSe2 to LT-GeSe2 is estimated to be 4.6 eV from the DSC measurement which corresponds to the boundary of the phases in the T-T-T diagram. The activation energy from LT-GeSe2 to HT-GeSe2 could not be obtained.
Evaluation of Thermal Expansion Coefficient of Twinned YBa2Cu3O7-δ Film for Prediction of Crack Formation on Various Substrates
Authors: Yamada Yasuji , Kawashima Junichi , Wen Jian-Guo , Niiori Yusuke , Hirabayashi Izumi
Published: October 2002

The effective thermal expansion coefficient of the
c-axis-oriented, twinned YBa2Cu3O7-δ (YBCO) film
formed on SrTiO3 (STO) substrates by liquid phase epitaxy was
evaluated by observing crack formation of the films. The critical
thickness of the YBCO film grown on STO at 920°C is about
1.35 µm. A simple fracture model with mechanical properties of
materials yields the effective thermal expansion coefficient of YBCO
film of about 14.0×10-6/K, as an engineering value for prediction of crack formation on various substrates. Temperature dependence in the thermal expansion of the substrate and the film suggests that control of oxygenation conditions enables us to suppress maximum stress induced in the films. According to the estimation, we predict the critical film thickness on various substrates used widely in oxide superconductor research.
Stability of Optical Dynamic Memory Operation under Period-Two State of Chaotic System
Authors: Fukushima Takehiro , Tanaka Teruhiko , Sakamoto Toyokazu
Published: October 2002

To realize optical dynamic memory operation with a simple
construction, we experimentally and theoretically investigated the
possibility of dynamic memory operation under a period-two state
of an optical chaotic system. We used an optoelectrical hybrid
chaotic system, employing the nonlinearity of injection locking of
the laser diode. During the fundamental oscillation of a period-two
state, we observed the dynamic response of the chaotic system
after an optical seed signal was injected. We also carried out
numerical simulations based on the rate equations. The signal was
stored for a few seconds after the optical seed signal was injected,
however, the memory operation lacked long-term stability. The numerical simulations well explain the decay of the injected optical seed signal. The simulation results showed that the
response time of the chaotic system must be significantly shorter
than the pulse width of the optical seed signal and the noise of the
system must be suppressed sufficiently to obtain stable memory
operation.
Preparation and Characterization of High Efficient Blue-Light Emitting Materials with a Secondary Ligand for Organic Electroluminescence
Authors: Qiu Yong , Shao Yan , Zhang Deqiang , Hong Xiaoyin
Published: October 2002

In this paper, a blue-light emitting material,
bis(2-methyl-quinolinolato)(phenolato)
aluminum(III) (Alq2
′OPh), was synthesized. Organic
electroluminescent (EL) devices have been fabricated with the homemade
organometallic compound as the emitting layer and
N,N′-diphenyl-N,N′-di(m-tolyl)benzidinev (TPD) as the hole transport
layer, blue light emission with a high efficiency was
obtained. Compared with tris (8-hydroxyquinoline) aluminum (Alq3),
the presence of the phenolato ligand shifts the light emission to the
blue region of the spectrum. The maximum wavelength of the EL is at
around 495 nm and the brightness is up to 4000 cd/m2 with the
maximum efficiency up to 1.4 lm/W. Two new compounds have also been
prepared in order to investigate the effect of the secondary
ligand. The comparison study indicates that the organometallic
compound with a secondary ligand, not only the sterical effect but
also some other effect would be responsible for the change of the
emission wavelength.
Crystal Structures of the TiO2 Films on the Quartz Substrate and the Powder formed in the Gaseous Phase by ArF Laser Photolysis of Ti(O-i-C3H7)4
Authors: Watanabe Akio , Tsuchiya Tetsuo , Imai Yoji
Published: October 2002

Decomposition of sublimed vapor of Ti-tetraisopropoxide by ArF laser has been
studied by X-ray diffraction. TiO2 crystalline films (anatase) were deposited on the
quartz substrate whereas the white powder of rutile was deposited on the inner wall of the
chamber through a decomposition reaction in the gaseous phase. The possible reasons
for the difference in the crystal structures of the deposits obtained on the substrate and in the gaseous phase are discussed.
Novel Photoalignment Materials for Liquid Crystals Based on Modified Polysiloxane
Authors: Liu Jia , Liang Xiao , Gao Hongjin
Published: October 2002

Novel photosensitive alignment materials based on
allyl-cinnamate-grafted methyl hydrogen polysiloxane fluid (MHPF) were
used in fabricating liquid crystal (LC) cells by sandwiching nematic
LC molecules between two indium-tin-oxide (ITO) patterned
substrates. The LC aligning ability of this kind of alignment layer,
fabricated by linearly polarized UV-induced polymerization (LPP), was
characterized based on polarizing microscopic and conoscopic
observations. The influences of the thickness of LPP films, LC
materials, different end groups, baking conditions and exposure
conditions on the alignment and thermal stability are discussed in
detail. The results confirmed that the photoalignment films exhibited
not only good aligning ability but also excellent thermal stability.
Ruby Scale at Low Temperatures Calibrated by the NaCl Gauge: Wavelength Shift of Ruby R1 Fluorescence Line at High pressure and Low Temperature
Authors: Nakano Kazutaka , Akahama Yuichi , Ohishi Yasuo , Kawamura Haruki
Published: October 2002

Wavelength shifts of the ruby R1 line at 10 K and 77 K were
measured as a function of pressure determined by the Decker equation
of state for NaCl up to 22 GPa. The wavelength shifts,
Δλ, of the R1 line increased almost linearly with
pressure both at 10 K and 77 K. Based on a linear least-squares
fit, the relation between pressure and Δλ is given as
P (GPa)=(2.748±0.012)Δλ (nm) at 10 K. The
coefficient is the same as that at room temperature.
Fabrication of Oxide Thermoelectric Generator Element
Authors: Shin Woosuck , Murayama Norimitsu , Ikeda Koichiro , Sago Sumihito
Published: October 2002

A prototype oxide thermoelectric element has been fabricated for the first time, for the application of power generation at high temperatures in air. Sintered bodies of Li0.025Ni0.975O(p-type) and Ba0.4Sr0.6PbO3 (n-type) were directly joined under the uniaxial pressure of 4 MPa at 1123 K for 10 h in air. The thermoelectric properties of this coupled element were measured in the temperature range of 440 to 1060 K. This element was stable and showed no appreciable contact resistance at the junction after a thermal cycle of over 1000 K. The output power and efficiency of the coupled element were calculated to be 14 mW and 0.64%, respectively, on the assumption that the temperatures of the hot and cold sides of the element were 1000 K and 500 K, respectively.
Thermal Expansion Coefficients of Optical Crystal CsLiB6O10
Authors: Yamada Sayu , Morimoto Yukihiro , Miyazawa Shintaro
Published: October 2002

Thermal expansions of bulk CsLiB6O10 (CLBO) crystal
were measured by a dilatomater for the first time. Thermal expansion
measurements were carried out in the temperature range between room
temperature and 500°C. The obtained expansion coefficients for
tetragonal c- and a-axes were -1.69±0.01×10-5/K and
2.12±0.01×10-5/K, respectively. The thermal expansion
coefficient along the c-axis was smaller than that reported
previously.
Synthesis of Amorphous Carbon Nitride Films Using Dissociative Excitation Reaction
Authors: Hidetoshi Saitoh Hidetoshi Saitoh , Hirosuke Takamatsu Hirosuke Takamatsu , Daisuke Tanaka Daisuke Tanaka , Noriko Ito Noriko Ito , Shigeo Ohshio Shigeo Ohshio , Haruhiko Ito Haruhiko Ito
Published: October 2002

In this investigation, we aim to produce highly nitrogen-doped carbon, so-called carbon nitride, films without the incorporation of hydrogen. In the physical vapor deposition process, irradiation by energetic nitrogen ions increases nitrogen content without the incorporation of hydrogen. In the chemical vapor deposition process, hydrogen should be included into the film due to the use of a hydrocarbon reactant. In this study, the synthesis of carbon nitride films having high nitrogen and low hydrogen contents was attempted using a chemical-vapor-deposition apparatus. First of all, a CH3CN+Ar mixture was selected as a reactant including hydrogen. Dehydrogenation of the reactant was carried out by plasma decomposition. Second, as a reaction system without hydrogen, BrCN+Ar was also selected for starting materials. The dissociative excitation reaction of cyanides with argon metastable atoms produces CN radicals, Ar(3P0,2)+BrCN →Ar+Br+CN(A2Π
i
, B 2Σ+, 4Σ+, 4Π). This finally proceeds to the deposition of CN radicals to form the carbon nitride film on a solid-state surface. When using the former reactant, large amounts of hydrogen remained in the amorphous carbon nitride films, although the amount of hydrogen varied with deposition conditions. The sample formed using the latter reactant was amorphous carbon nitride with very little hydrogen. The nitrogen fraction [N]/([N]+[C]) of the sample using the latter rectant is as high as ∼0.3, higher than those obtained from the samples synthesized with the former reactant.
Interfacial Solid-Phase Reaction in Al/HfN/Hf/Si Contact System during Postmetallization Annealing
Authors: Satoko Shinkai Satoko Shinkai , Katsutaka Sasaki Katsutaka Sasaki
Published: October 2002

We investigated the sequential single-oriented growth of Al/HfN/Hf trilayered film on Si and the interfacial solid-phase reaction of a Al/HfN/Hf/Si contact system by X-ray diffraction and Auger electron spectroscopy. Since for preparing this contact system, the deposition of HfN film was carried out on a Hf/Si system at a temperature of 450°C, which is higher than the silicidation temperature of Hf3Si2 (420°C), we also confirmed whether the formation of a Hf3Si2 region with the lowest contact resistivity could be ensured at the Si interface during the deposition of HfN film. As a result of postannealing, it was revealed that the Al overlayer can be preserved at least up to 440°C and the region of Hf3Si2 phase is maintained at the Si interface up to 500°C.
Chemical-Vapor-Deposited Diamond Overgrowth on Platinum Thin Films Deposited on Diamond Substrates
Authors: Wang Chunlei , Ito Toshimichi
Published: October 2002

Overgrowth characteristics of B-doped diamond
chemical-vapor-deposited on thin Pt films (with thicknesses of
100–200 nm) that were sputter-deposited on polycrystalline and
single-crystalline diamond substrates have been studied by scanning
electron microscopy with X-ray emission analysis, Raman scattering
spectroscopy and a conventional X-ray diffraction method. The main
feature observed is that a complex three-dimensional structure of
polycrystalline Pt is formed in the overgrown diamond layer for both
types of diamond substrates used. This suggests that significant
agglomeration and recrystallization of the thin Pt film occurred at
∼900°C, well below the Pt melting point of 1772°C,
during the
diamond overgrowth process. A considerable amount of B segregation
was also observed after the overgrowth. It is concluded that a
sputter-deposited Pt thin film with a thickness of 100–200 nm is
not suitable as a mask usable in fabrication processes of
multilayered diamond structures.
Fabrication and Annealing Effect of c-Axis Orientated Potassium Lithium Niobate Thin Film on Glass Substrate
Authors: Park Sung-Kun , Bae Seoung-Choon , Choi Byung-Jin , Nam Gi-Hong , Kim Young-Jin , Kim Ki-Wan
Published: October 2002

Potassium lithum niobate (KLN; K3Li2Nb5O15) thin films
were prepared by an rf-magnetron sputtering technique using a sintered K- and
Li-excessed target. In this experiment the optimum sputtering conditions were an rf
power of 100 W, working pressure of 150 mTorr, and substrate temperature of
600°C. When the KLN was grown on a Corning 1737 glass substrate at a
temperature of 600°C with a sputtering pressure range of 50–200 mTorr, the
thin film KLN was (001) oriented. The (001) preferred orientation of a KLN thin film is
due to the minimum surface energy of the (001) plane. The lattice constant of an
as-grown thin film has a slightly larger value than the tetragonal tungsten bronze
structure range. The lattice constant and full width half maximum (FWHM) of the
thermal-treated films were shrunk by the stress relaxation of the thin film. When
annealing at a temperature of 650°C the value of the lattice constant of the
c-axis was in the middle of the tetragonal structure range. Accordingly, the use of a
K- and Li-enriched sintered KLN target enables the fabrication of c-axis-oriented
ferroelectrics directly onto an amorphous substrate.
Effects of Deposition Pressure on the Properties of a Low-Dielectric Constant Cyclohexane-based Plasma Polymer
Authors: Quan Yong Chun , Joo Jongryang , Yeo Sanghak , Jung Donggeun
Published: October 2002

The effects of deposition pressure on the properties of cyclohexane-based plasma polymer (CHexPP) thin films were investigated. Deposition of CHexPP thin films at higher deposition pressures was associated with lower deposition rates and produced thin films with lower k-values, lower thermal stabilities and higher etching rates. It is considered that the higher deposition pressure decreases the energies of the charged reactive species generated by the plasma from the precursor molecules, resulting in less dense and less well cross-linked plasma polymer thin films.
Mechanism of Nitrogen Incorporation into Amorphous-CNx Films Formed by Plasma-Enhanced Chemical-Vapor Deposition of the Doublet and Quartet States of the CN Radical
Authors: Haruhiko Ito Haruhiko Ito , Noriko Ito Noriko Ito , Tsutomu Takahashi Tsutomu Takahashi , Hirosuke Takamatsu Hirosuke Takamatsu , Daisuke Tanaka Daisuke Tanaka , Hidetoshi Saitoh Hidetoshi Saitoh
Published: October 2002

High-resolution CN(B2Σ+–X2Σ+) emission spectra were observed for the various processes to form amorphous-CN
x
(a-CN
x
) films using the plasma-enhanced chemical-vapor deposition of the CN radical produced from the dissociative excitation reactions of cyanides. A strong correlation was confirmed between the electronic states of CN in the plasma and the bonding states of nitrogen atoms in the films. The 4Σ+ and 4Π states of CN were the precursors of the one- and/or two-dimensional C=N and C–N network structures of the films with high nitrogen content, [N]/([N]+[C]) ≤0.5. The CN(X2Σ+) state formed the C≡N terminations primarily, a part of which changed to the one-dimensional C=N network from the additive reactions. The above correlation was fully explained by the molecular orbitals and the electronic configurations for the relevant electronic states of CN.
Analysis of Deprotection Reaction in Chemically Amplified Resists Using an Fourier Transform Infrared Spectrometer with an Exposure Tool
Authors: Sekiguchi Atsushi , Miyake Yasuhiro , Isono Mariko
Published: October 2002

The reaction of dissociation of protection groups (hereafter the “deprotection reaction”) was observedin situduring exposure of chemically amplified resists using an Fourier transform infrared (FT-IR) spectrometer equipped with an exposure unit, at a wavelength of 248 nm. The deprotection reaction in the chemically amplified resists during exposure was modeled on the basis of thein situIR measurement results, and the deprotection reaction constantC2, reaction initiation delay constantE0, and average acid lifetime constant τ2were calculated. Herein, we report our results. The chemically amplified resists used in the experiments were based on polystyrene (PS) and had a t-butoxycarbonyl (t-BOC) protection group (hereafter “t-BOC resist”) and a 1-ethoxyethyl (ethyl acetal) resist (hereafter “EA resist”). The deprotection reaction in the t-BOC resist was observed through changes in the infrared spectrum at 1150 cm-1(C–O ester bonds); the deprotection reaction in the EA resist was monitored through changes in the infrared spectrum at 2980 cm-1(H–C–H alkane bonds). It was found that at room temperature (23°C), whereas the deprotection reaction in the t-BOC resist during exposure occurred to the extent of only was only 5% complete, it occurred nearly to completion in the EA resist. The change in absorption with exposure time was converted into a protection ratio for protection groups, and fitted to a newly devised deprotection reaction model to estimate the deprotection reaction parameters for exposure. The deprotection reaction parameters thus obtained were input in to a profile simulator, and profile simulations were attempted. The results indicated that whereas the t-BOC resist could be patterned at an ambient a temperature of 70°C and above during exposure, the EA resist could be patterned at room temperature. In resist development and studies of resist processes, this system is expected to prove useful for the analysis of deprotection reactions during exposure.
Linear Electro-optic Effect of 0.88Pb(Zn1/3Nb2/3)O3–0.12PbTiO3 Single Crystal
Authors: Lu Yu , Cheng Zhong-Yang , Park Seung-Eek , Liu Shi-Fang , Zhang Qiming
Published: October 2002

The linear electro-optic (E-O) coefficients of poled
0.88Pb(Zn1/3Nb2/3)O3–0.12PbTiO3 single crystal
were characterized using an automated scanning Mach-Zehnder
interferometer and the senarmont compensator method at room
temperature. They were obtained at a wavelength of 632.8 nm:
r
33=134 pm/V, r
13=7 pm/V, r
51=462 pm/V, and
r
c=131 pm/V respectively and the refractive indices:
n
e=2.57 and n
o=2.46. The large r
51
coefficient compared with r
33 is caused by the high dielectric
constant at perpendicular to the polar-axis compared with the
dielectric constant along the c-axis. Comparison with the quadratic
E-O coefficients measured at near and above the Curie temperature
suggests that the values of the quadratic E-O coefficients measured
earlier may be smaller than the intrinsic ones due to the influence of
micro-polar regions. The development of an automated scanning
Mach-Zehnder interferometer, which is less susceptible to the errors
caused by the laser intensity fluctuation and drafting in the optical
path length in the system, is also described.
Analysis of Resist Pattern Collapse by Direct Peeling Method with Atomic Force Microscope Tip
Authors: Kawai Akira , Kaneko Yoshihisa
Published: October 2002

Quantitative analysis of the adhesion property of a KrF resist
pattern is demonstrated experimentally. Dependency of the load for
collapse on various line and L-shaped patterns, is investigated. By
directly applying normal load with a microcantilever tip, a
photoresist pattern adhering on a substrate can be collapsed
easily. The adhesion strength of the L-shaped pattern is
considerably large as compared with the line pattern. The
reliability of this method is discussed together with the analysis
of stress distribution in the KrF resist patterns.
Nonsteady Flow in Capillary Tubes
Authors: Hara Ayako
Published: October 2002

Surface phenomena in the field of electron devices and the problem of how
long. It takes
plants to absorb water during their growth in hydroponic cultivation is
attraching the attention of
riseachers. However, the related study of non-steady flow in capillary
tubes has a number of issues that require investigation. In response to
this situation, we made attempted to assess nonsteady fiow in capillary
tubes, the liquid rise time and other issues, using a motion equation that
takes factors including the friction force of the tube and the surface
tension into consideration.
Dependence of Transport Mean Free Path on Size of Scatterer
Authors: Mitani Shujiro , Sakai Keiji , Takagi Kenshiro
Published: October 2002

The transport mean free path l
* characterizing the light
diffusion phenomenon
in highly dispersed media was theoretically predicted and compared
with the values
observed by the experiments of coherent backscattering. The Mie
scattering theory for
a spherical particle was used to calculate the scattering cross
section, that leads to the l
*
of the suspension together with the number density of the particles.
The anisotropy in
a single scattering process was also taken into account. A series of
experiments was
made in polystyrene latex with 5% and 10% volume fractions and
different diameters
ranging from 0.1 µm to 3 µm. The experimental values of
l
* obtained
from the
coherent backscattering peak were in good agreement with the
theoretical predictions.
This study is performed to give a solid base to the coherent
backscattering phenomenon
as a new approach for material evaluation of dispersed media.
Design of Temperature Independent Add/Drop Filter Using Vertical Coupled ARROW Filter
Authors: Tak Chu Shuichi Suzuki , Yasuo Kokubun Yasuo Kokubun
Published: October 2002

In the stacked crossing-type vertical coupler filter, the athermal waveguide cannot eliminate the temperature dependence of the center wavelength. Thus, a temperature-independent stacked vertical coupler filter (VCF) was proposed and designed by adjusting the temperature dependence of equivalent indices of two waveguides. The required measurement accuracy of the temperature coefficient of the refractive index was investigated and a new method was introduced to design the athermal anti-resonant reflecting waveguide (ARROW)-type VCF.
InGaAsP/InP Laterally Coupled Distributed Feedback Ridge Laser
Authors: Chen Nong , Watanabe Yoshiaki , Takei Kiyoshi , Chikuma Kiyofumi
Published: October 2002

A 1.3-µm-wavelength InGaAsP/InP laterally coupled distributed feedback ridge laser with
improved structure and characteristics is reported in this paper. For easier fabrication of
the first order grating with 198 nm period on and beside the ridge waveguide side-walls,
two-step etching has been used to form a narrow ridge waveguide with a special shape.
The grating is patterned by electron beam lithography and deeply
transferred also by two-step etching, in order to enhance the lateral
evanescent field coupling. A stable CW laser oscillation with a low
threshold current of 17 mA at room temperature and a high side mode
suppression ratio of 45 dB for a laterally coupled distributed
feedback ridge laser has been achieved. An external slope efficiency
of 0.25 W/A and an output power of about 25 mW are also available in
our most recent devices with anti-reflection and high reflection facet
coatings. The optical transmission of a Gbit/s order modulated signal
has also been tested using our preliminary laser modules through a
1 km optical fiber.
Analysis of Conformational Transition Effect on Maxwell Displacement Current: A Kinkable Rod Model
Authors: Zhao Wei , Wu Chen-Xu , Iwamoto Mitsumasa
Published: October 2002

We suggest a simple molecular model to analyze the compression-induced Maxwell-displacement-current (MDC) behavior of a Langmuir monolayer. The constituent chain molecule is viewed as a kinkable rod, with the kink schematizing the possible trans-gauche isomerization of organic chains. The use of the concept of kink is an attempt to improve the well-known rodlike model. Our analysis indicates that this model is beneficial for recognition of MDC behavior of monolayers.
Kinetics of GaAs Metalorganic Chemical Vapor Deposition Studied by Numerical Analysis Based on Experimental Reaction Data
Authors: Sugiyama Masakazu , Feron Olivier , Sudo Sinya , Nakano Yoshiaki , Tada Kunio , Komiyama Hiroshi , Shimogaki Yukihiro
Published: October 2002

In order to develop a computer-assisted process optimization of
In1-x
Ga
x
As
y
P1-y
metalorganic chemical vapor deposition (MOCVD),
the kinetics of GaAs growth was studied as the first step. For the accumulation of
reaction data of source materials, the decomposition rates of trimethylgallium (TMGa)
and tertiarybutylarsine (TBAs) were studied using a flow tube reactor and a Fourier
transform infrared spectrometer (FT-IR). Special attention was paid to the effect of
TBAs concentration on the decomposition rates of TMGa. The GaAs growth rate profile
in a commercial MOCVD reactor was analyzed through both experiment and simulation.
The profile was dependent on the gas velocity and total pressure. This dependency was
explained by a reaction model which was deduced from the experimental observations:
TMGa decomposes to a gas-phase intermediate which subsequently forms the GaAs
film. The fluid dynamic calculations combined with this reaction model led to growth
rate distributions which agreed well with the experimental data. The analysis revealed
that the GaAs growth rate is limited by the gas-phase reactions of TMGa as well as the
mass-transport of the intermediates, and that precise measurement of the reaction
between TMGa and TBAs is essential for an accurate simulation.
Heat Treatment of Boron-Doped CdS Films Prepared by Chemical Bath Deposition for Solar Cell Applications
Authors: Jae-Hyung Lee Jae-Hyung Lee , Ho-Yeol Lee Ho-Yeol Lee , Jeong-Ho Kim Jeong-Ho Kim , Yong-Kwan Park Yong-Kwan Park
Published: October 2002

Effects of annealing on the properties of boron-doped CdS films prepared by chemical bath deposition using boric acid as a dopant source were investigated. The crystalline orientation and the grain size of CdS films appeared to be seriously affected by the annealing ambient. The crystal structures of H2-annealed films were wurtzite type with a preferential orientation of the (002) plane and the grain size slightly increased. For samples annealed in N2 and air, however, the preferential orientation of the (002) plane disappeared or decreased and the grain size was identical to or smaller than that for H2 ambient. The dark resistivity decreased by annealing in H2 and increased further with increasing annealing temperature. For N2 and air ambient, the dark resistivity was larger than that of the H2-annealed films and the optical transmittance was less than that of the H2-annealed films. These results suggest
that annealing in H2 ambient is suitable for photovoltaic device application.
Optical Modes in Two-dimensionally Ordered Dielectric Spheres
Authors: Masanobu Haraguchi Masanobu Haraguchi , Teruo Nakai Teruo Nakai , Akihiko Shinya Akihiko Shinya , Toshihiro Okamoto Toshihiro Okamoto , Masuo Fukui Masuo Fukui , Takao Koda Takao Koda , Ryoko Shimada Ryoko Shimada , Kazuo Ohtaka Kazuo Ohtaka , Kenji Takeda Kenji Takeda
Published: October 2002

We have experimentally observed the optical modes of periodic two-dimensionally ordered polystyrene spheres with a diameter of 5.15 µm using the attenuated total reflection method. The dispersion relation of such optical modes clearly shows that there are two types of propagating modes in the ordered spheres. We point out that one of the two optical modes is related to the guided modes in optical fibers and the periodicity of the spheres plays an important role in its excitation mechanism. The other mode propagates along spherical surfaces.
Characteristics of Excimer-Laser-Induced Luminescence of the Ground Surface of Silica Glass
Authors: Yoshizo Kawaguchi Yoshizo Kawaguchi , Nobu Kuzuu Nobu Kuzuu
Published: October 2002

Characteristics of excimer-laser-induced luminescence of the ground surface of synthetic fused silica containing various amounts of OH were investigated. KrF (5.0 eV) and ArF (6.4 eV) lasers with a repetition rate of 20 Hz and energy densities of 44 and 53 mJ/cm2, respectively, were used. The luminescence spectra had peaks at 1.9, 3.5, and 2.5–3 eV. Intensity at 1.9 and 3.5 eV decreased with increasing irradiation time. The decrease of the intensity of the 1.9 eV band suggests the destruction of nonbridging oxygen-hole centers (NBOHCs; ≡Si–O·). The change of the luminescence around 2.5–3 eV was rather complex; the luminescence spectra approached a single Gaussian band at 2.7 eV after irradiation with both types of excimer laser for 10 min. In silica containing 90 ppm of OH, the peak intensity of the 2.7 eV band after irradiation for 10 min was stronger than the initial peak intensity at 2.9 eV, whereas the ratio between these peaks in silica containing 1200 ppm of OH was reversed. The origin of this difference is discussed.
Liquid Crystal System as Molecular Machinery: Investigation of Dynamic Impedance Matching between Molecular Core and Terminal Groups Using Rotor-Bearing Model
Authors: Jun Xu Jun Xu , Hiroyuki Okada Hiroyuki Okada , Hiroyoshi Onnagawa Hiroyoshi Onnagawa , Shigeru Sugimori Shigeru Sugimori , Kazuhisa Toriyama Kazuhisa Toriyama
Published: October 2002

Liquid crystal phase stability is examined for liquid crystal terphenyls and their fluorinated derivatives, and some general rules are proposed that relate phase stability to molecular structures. A mechanical model is applied to explain the phase behaviours of these compounds. We postulate that liquid crystal phases are micromachine systems consisting of an ensemble of molecular rotors. The molecular core and terminals are the rotor and axes, respectively. The terminals also function as bearings for the subsequent layer's molecular rotors. Phenomena of the thermal stability of phase and polymorphism are interpreted in terms of basic mechanical and dynamical parameters: centre of gravity, eccentricity, moment of inertia and mass distribution. The importance of dynamic impedance matching between parts, rotors, axes and bearings, is emphasized. Fluorination effects on liquid crystallinity are explained in a unified manner on a mechanical and dynamical basis.
Enhanced Orientation in Langmuir–Blodgett Films of Tetra-tert-butyl Phthalocyanines
Authors: Toshihiko Matsuura Toshihiko Matsuura , Tomohiro Komatsu Tomohiro Komatsu , Eiji Hatta Eiji Hatta , Yuhei Shimoyama Yuhei Shimoyama
Published: October 2002

We report the results of structural investigations on Langmuir (L) and Langmuir–Blodgett (LB) films of tetra-tert-butyl phthalocyanine (MTBPC) containing various transition metal ions. Techniques were developed for fabricating well-ordered L-monolayers using a flow-orientation method that dramatically enhances the molecular orientation of MTBPC in L-monolayers as compared to other techniques. The dilution procedure for developing solutions enables the formation of a well-defined single L-monolayer at the air–water interface. The tilt angles of MTBPCs in the L-monolayers are estimated by the limiting area technique. The tilting structure of LB films of MTBPCs on glass substrates as measured by X-ray diffraction (XRD) method is in good agreement with the estimate obtained by the limiting area technique on the corresponding L-monolayers. An annealing procedure significantly improves the ordering of the LB films as measured by XRD.