bluuebunny/crossref_metadata_2025 huggingface dataset:
Photo-Leakage Current of Poly-Si Thin Film Transistors with Offset and Lightly Doped Drain Structure
Authors: Kobayashi Kazuhiro , Niwano Yasunori
Published: October 2002

The suppression of photo-leakage current (I
photo) has been an important issue in the fabrication of high-brightness liquid-crystal projectors. We have investigated the generation mechanism of I
photo in poly-Si thin film transistors (TFTs) with an offset structure. It is found that I
photo is mainly generated at the offset region and the decrease in the offset length is important to suppress I
photo. This is because the electric field is applied to the offset region and carriers, generated in the region, can be extracted. We have realized an offset poly-Si TFT with both high mobility and low I
photo by decreasing the offset length to 0.5 µm with the lateral etching method.
Structural Inhomogeneity in Hydrogenated Amorphous Silicon in Relation to Photoelectric Properties and Defect Density
Authors: Sakikawa Nobuki , Tamao Masaki , Miyazaki Seiichi , Hirose Masataka
Published: October 2002

Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) is suppressed by applying a positive dc-bias to an rf-electrode (cathode) of a capacitively-coupled reactor at high deposition rate (2–2.7 nm/s) conditions. Reduction of the ion flux impinging on the growing film surface under positive dc-bias results in a decrease of the defect density, while the total content in the deposited films is almost independent of dc-bias. It is found that the defect density after light soaking is decreased by reducing the structural inhomogeneity, as confirmed by small-angle X-ray scattering analysis and electron spin resonance measurement.
Solution Growth Combined with Solvent Evaporation: A Novel Technique in Solution Growth
Authors: Sato Kenji , Seki Yoji , Oda Osamu
Published: October 2002

A new method for solution growth, referred to as “solution growth combined with solvent
evaporation”, was devised. A solvent is evaporated from a crucible to a space for
condensing the solvent by controlling the temperature profile of the furnace. This technique
was applied to the solution growth of ZnTe, using Te as a solvent. A single crystal of ZnTe
with no cracks and low dislocation densities was obtained by this method combined with a
hetero-seeding method on a sapphire substrate.
Optical Characterization of Impact Ionization in Flip-Chip-Bonded InP-Based High Electron Mobility Transistors
Authors: Naoteru Shigekawa Naoteru Shigekawa , Tomofumi Furuta Tomofumi Furuta , Tetsuya Suemitsu Tetsuya Suemitsu , Yohtaro Umeda Yohtaro Umeda
Published: October 2002

Impact ionization in flip-chip-bonded InP-based high electron mobility transistors (HEMTs) with 0.1-µm gates is examined by measuring their electroluminescence (EL). We extract quantities proportional to the concentration of impact-ionization-induced holes at the source edge and the impact ionization probability of a single electron for a wide range of bias voltages. The lateral extension of the high-field region at the drain edge, where the impact ionization occurs, is also estimated. Furthermore, the EL signal from each of two neighboring HEMTs separated by 20 µm is clearly resolved in the spatial distribution measurement, which suggests that the present method is also applicable for characterizing individual devices in actual ICs.
Work Function Changes of GaAs Surfaces Induced by Se treatment
Authors: Suzuki Satoru , Maeda Fumihiko , Watanabe Yoshio , Ohno Takahisa
Published: October 2002

Effects of a Se treatment on the work function of epitaxially grown GaAs surfaces were measured by photoemission spectroscopy. Although the Se treatments reduced the band bending of n-type GaAs, the work function increased. This result indicates that the surface component of the work function increased and that the surface dipole moment, whose direction was from the surface to the bulk (outer layer: -, inner layer: +), was formed at the Se-treated GaAs surface. On the other hand, qualitative analysis based on the electron counting model revealed that the direction of the surface dipole in the previously proposed structural model of Se/GaAs(001) was completely opposite to that obtained in our experimental results. It is suggested that this discrepancy is due to the vacancies in the internal Ga layer in the structural model.
Temperature Dependence of Internal Quantum Efficiency of 20-nm-Wide GaInAsP/InP Compressively-Strained Quantum-Wire Lasers
Authors: Arai Takashi Kojima
Published: October 2002

We evaluated the temperature dependence of the internal quantum efficiency of 1.5-µm-wavelength
GaInAsP/InP compressively-strained 20-nm-wide quantum-wire lasers from the cavity length dependence of
the differential quantum efficiency.
As a result, high internal quantum efficiency ηi∼1.0 was obtained at T<200 K,
which decreased with an increase in temperature.
Femtosecond Pulse Shaping with Twisted-Nematic Liquid-Crystal Spatial-Light Modulators
Authors: Toshiaki Hattori Toshiaki Hattori , Kouhei Kabuki Kouhei Kabuki , Yoshitsugu Kawashima Yoshitsugu Kawashima , Masahiro Daikoku Masahiro Daikoku , Hiroki Nakatsuka Hiroki Nakatsuka
Published: October 2002

Shaping of 16 fs optical pulses using a twisted-nematic (TN) liquid-crystal spatial-light modulator (SLM) was conducted. The properties of TN SLMs were characterized theoretically and experimentally, and the relevant mode extraction method was developed for the SLM mask pattern design using a simulated annealing algorithm. Phase-sensitive pulse shaping using a TN SLM was performed and the shaped waveforms were observed by measuring the interferometric
intensity cross-correlation with unshaped pulses.
Fabrication and Optical Properties of Two-Dimensional Ordered Arrays of Silica Microspheres
Authors: Yamasaki Takashi , Tsutsui Tetsuo
Published: October 2002

Two-dimensional ordered arrays of SiO2 (silica) microspheres, as a semi-two-dimensional photonic crystal, with large surface area were fabricated by using a newly developed self-organization method. We observed strong light scattering and hexagonal diffraction patterns for the hexagonally close-packed array of spheres with submicrometer size. Dips in the transmission spectra due to coupling between incident light and electromagnetic bound states of the photonic bands within the array were observed. From the transmission spectra, we determined the photonic band structure of the two-dimensional arrays of microspheres.
Resonant Properties of Long-Range Surface Plasmons in an Arbitrary Multilayer Structure
Authors: Liao Chih-Hsiung , Lee Cheng-Min , Cheng Yuan-Tung , Shyu Jiann-Shing , Su Wen-Kuan
Published: October 2002

In this study, properties of long-range surface plasmons (LRSPs)
in an arbitrary multilayer structure have been investigated. We
derived an approximation of the reflectivity from Fresnel
formulas. Furthermore, the resonant properties of LRSPs have been
calculated. As a result of the simulations, we conclude that the
difference in resonant angles decreases as the metal thickness
increases, and the damping rate obtained from the Sarid geometry is
lower than that obtained from the Kretschmann geometry. The resonant
half-width obtained from the Sarid geometry is narrower than those
obtained from the Kretschmann and Otto geometries. As far as SP
chemical sensors are concerned, the system based on the Sarid geometry
is better than that based on the Kretschmann or Otto geometry.
Domain Motion in Bismuth-Layer-Structured Ferroelectrics by Applying Electric Fields
Authors: Irie Hiroshi , Miyayama Masaru , Kudo Tetsuichi
Published: October 2002

Domain wall motion and polarization reversal time along the a–b plane in single crystals of various bismuth-layer-structured ferroelectrics (BLSFs) are described. Direct observation of domain wall motion by applying an electric field was performed using a polarizing microscope. By applying an electric field parallel to the domain walls, extinction of domain walls and production of new domain walls perpendicular to the former ones were observed. By applying an electric field at an angle of 45° from the domain walls, extinction of domain walls, in short, `poling', was observed. The process of domain wall motion was similar regardless of the kind of BLSF used. From the electric field dependence of the polarization reversal time, domain wall motion was found to be a forward one due to a nucleation mechanism. This motion was consistent with that observed directly using the polarizing microscope. The velocity of domain wall motion was dependent on the kind of BLSF used; the velocity was higher in BLSF with a large number of RO6 octahedra between bismuth layers.
Orientational Transition of P-pentyl-p'-cyano-biphenyls Triggered by Conformational Change of Surface Azobenzene Monolayer
Authors: Iwamoto Mitsumasa , Kato Keisuke , Matsumura Atsushi , Majima Yutaka
Published: October 2002

We examined the orientational transition process of p-pentyl-p'-cyano-biphenyl (5CB) molecules in liquid-crystal (LC) cells triggered by the conformational change of the surface azobenzene monolayer on polyimide (PI) Langmuir-Blodgett (LB) films, by measuring the optical transmittance and the electrical capacitance simultaneously. The experimental results were analyzed using a continuum theory describing the free energy of LC cells. It was shown that the motion of 5CB molecules triggered by the surface azobenzene monolayer on PI LB films was ruled by the continuum theory. The transmittance and the capacitance of the LC cells with 1-layer PI LB films were changed reversibly by the alternating irradiation of ultraviolet (UV) and visible light, whereas those of LC cells with 5- and 11-layer PI LB layers were not changed reversibly. These results were discussed, taking into account the difference in the anchoring strength of PI LB films.
Modeling and Computer Simulation of the Electrooptic Response of Polymer-Stabilized Ferroelectric Liquid Crystal Cells
Authors: Taiju Takahashi Taiju Takahashi , Takeshi Umeda Takeshi Umeda , Hirokazu Furue Hirokazu Furue , Shunsuke Kobayashi Shunsuke Kobayashi
Published: October 2002

The dynamical electrooptic (EO) response of mesogenic side-chain polymer-stabilized ferroelectric liquid crystal cells has been investigated based on the continuum theory. From numerical calculations, the transition from the bistable EO response to the monostable EO response for pulse-applied voltages is clearly demonstrated with increasing degree of polymer stabilization, where free energy originating from the polymer stabilization is formulated and adopted. The reduction of the fall time constant is revealed in this transition. These behaviors are shown to be in qualitative agreement with the results of independent experimental measurements.
Multi-Stacked InAs/InGaAs/InP Quantum Dot Laser (Jth=11 A/cm2, λ=1.9 µm (77 K))
Authors: Zaitsev Sergey V. , Gordeev Nikita Yu. , Kopchatov Vladimir I. , Ustinov Victor M. , Zhukov Alexey E. , Egorov Anton Yu. , Kovsh Alexey R. , Kop'ev Peter S.
Published: October 2002

Self-organized InAs quantum dots inserted in an (In, Ga)As matrix lattice matched to InP
substrate were used as an active region of an injection laser. Low threshold (11 A/cm2) lasing at
1.9 nm (77 K) via the quantum dot states was realized. Temperature dependencies of the main laser
parameters demonstrate the important role of the nonradiative recombination. An analysis of basic
mechanisms of leakage shows that the Auger recombination share is negligible.
Optical Emission Spectra during Carbon Nanotube Production by Arc Discharge in H2, CH4 or He Gas
Authors: Xinluo Zhao Xinluo Zhao , Tsugio Okazaki Tsugio Okazaki , Atsuo Kasuya Atsuo Kasuya , Hiroshi Shimoyama Hiroshi Shimoyama , Yoshinori Ando Yoshinori Ando
Published: October 2002

Optical emission spectra during carbon nanotube production by DC arc discharge in H2, CH4 or He gas were investigated. Emission spectra for C(I) (neutral carbon) atoms and C2 dimers were commonly observed in the three gases. The existence of H atoms and CH molecules was verified by in situ observation during the evaporation in H2 or CH4 gas, because strong H and CH spectra were identified. It was concluded that H atoms were conducive for production of high-quality multiwalled carbon nanotubes by means of forming hydrocarbon species, but were not conducive for production of C60 and C70.
Effects of Addition of SiF4 During Growth of Nanocrystalline Silicon Films Deposited at 100°C by Plasma-Enhanced Chemical Vapor Deposition
Authors: Ali Atif Mossad , Inokuma Takao , Kurata Yoshihiro , Hasegawa Seiichi
Published: October 2002

Structural properties of nanocrystalline silicon (nc-Si) films, deposited at 100°C using SiF4/SiH4/H2 by plasma-enhanced chemical vapor deposition, were investigated by changing the SiF4 flow rate, [SiF4]. At a certain low [SiF4] value (=[SiF4]S), both the crystallinity and the grain size had minimum values. The Raman peak shifts corresponded well with a change in stress, and films with [SiF4]S were suggested to be free from random stress in the local Si–Si networks. The photoluminescence spectra had the highest intensity and the highest peak energy at [SiF4]S. It was proposed that nc-Si films with high [SiF4] have microvoid-like grain boundaries with high densities of Si–F and SiH2 bonds, exhibiting an increase in crystallinity and susceptibility to O contamination after deposition. These results were interpreted in terms of the change in the etch rates by H and F radicals, depending on deposition temperature.
Room-Temperature Operation of In0.5Ga0.5As Quantum Dot Lasers Grown on Misoriented GaAs Substrates by Molecular Beam Epitaxy
Authors: Nee Tzer-En , Yeh Nien-Tze , Shiao Po-Wen , Chyi Jen-Inn , Lee Ching-Ting
Published: October 2002

We have investigated the characteristics of self-assembled In0.5Ga0.5As quantum dot lasers grown on three types of (100) GaAs substrates, i.e. 0°, 4° and 15°-tilted toward the (111)Ga plane. The lasing wavelength at room temperature is 1018 nm, 1015 nm, and 1030 nm for the 0°, 4° and 15°-0ff samples, respectively. Due to the better quantum confinement and arrangement of the quantum dots, the 4o-off samples exhibit a lower threshold current of 47 mA at room temperature, compared to 73 and 65 mA for the 0° and 15°-off samples, respectively. For the same reason, the characteristic temperature obtained between 150 and 300 K is 117 K for the 4°-off samples, compared to 113 K and 100 K for the 0° and 15°-off samples, respectively.
Monochromatic Electron Emitters using Heavy-Fermion Materials
Authors: Nishiyama Hidetoshi , Ohshima Takashi , Okamoto Masakuni
Published: October 2002

To obtain electron emission with a narrower energy width than 0.1 eV, we studied field emitters using heavy-fermion materials. These materials have f electrons with large effective mass ranging from 10 to 1000. This study used free-electron model calculations with effective mass approximation. The energy width decreased by four-fifths when effective mass increased from 1 to 200. The relationships between effective mass, f electron density, and energy width were determined. These relationships enabled us to choose materials with a narrow energy width. It was found that for an energy width narrower than 0.1 eV, f electron density must be larger than 0.05 Å-3 at an effective mass of 100 or 0.1 Å-3 at an effective mass of 200.
Instability Analysis of Rotating Plasma in Stationary Gas
Authors: Hashimoto Junichi , Muranaka Takanobu , Nakashima Hideki
Published: October 2002

A numerical study is conducted using a magnetohydrodynamics (MHD)
code to analyze a unique plasma structure–the persistent spiral arm
structure–observed in experiments by Ikehata et al.. [Phys. Rev. Lett. 81
(1998) 1853]. The numerical simulation suggests that the structure is caused
by centrifugal instability as proposed by them.
Molecular Orbital Approach to the Electronic Structure of CdS Ultrafine Particles
Authors: Okano Kiyohisa , Hayashi Toyoharu , Miyamoto Akira
Published: October 2002

The electronic structure of CdS ultrafine particles was studied by the semiempirical molecular orbital (MO) method. A practical procedure to perform MO calculations on a very large molecule which contains roughly one thousand atoms was established. The aimed electronic structure was obtained and characterized. A tendency which corresponds to the so-called size quantization effect usually observed in semiconductor ultrafine particles was confirmed. An electronic transition energy, which was almost comparable to experimental data, was obtained. The influence of surface structures on the electronic state was directly calculated by the MO method. Low-coordinated Cd atoms were found to produce surface states. A surface defect site associated with excess Cd was simulated by introducing a sulfur vacancy. A new MO that originated from the defect site, which may act as a trapping site of excited electrons, was identified.
Optimizing the Lighting in Automatic Inspection System using Monte Carlo Method
Authors: Chen Li , Wang Xinsheng , Suzuki Masafumi , Yoshimura Noboru
Published: October 2002

The lighting affects the cost, stability and quality of image formation in an inspection system. The inspection results are simultaneously affected by such as the light configuration, the reflectance of the inspected object, and the performance of lens, therefore it is difficult to supply the resolution either by measuring or analytical methods. The illumination effect of two different light sources in an automatic inspection system is studied by means of Monte Carlo (MC) method in this paper. The theoretical analysis and simulation results reveal as follows: It is possible to examine the performance of the different light sources and the reflection characteristics of the inspected object in an automatic inspection system by MC simulation method. When the size and the surface roughness of the inspected object vary, the collection result of lens under a desired annular light source has a better effect than under a sloped planar light source. However, with the reflector depth of the annular fluorescent lamp increasing, the efficiency decreases. This research not only supplies an available method for the analysis of light configuration but also points out a new way for light source selection in an automatic inspection system.
Development of a Lidar System for Measuring Methane Using a Gas Correlation Method
Authors: Minato Atsushi , Joarder MD. Mahbubul Alam , Ozawa Satoru , Kadoya Minoru , Sugimoto Nobuo
Published: October 2002

We developed a laser long-path absorption lidar system using a
gas correlation method for measuring atmospheric methane. This
technique uses a broad-band laser and a gas correlation cell. We
developed a potassium titanyl arsenate (KTA) optical parametric
oscillator at 3.416 µm for the laser source. The optical
round-trip path length is 20 m. The experiment was carried out using
this system. It was estimated that the error in the density of methane
is 4.4 ppm for measurement within 1 s.
Highly Resolved Maskless Patterning on InP by Focused Ion Beam Enhanced Wet Chemical Etching
Authors: König Harald , Reithmaier Johann Peter , Forchel Alfred
Published: October 2002

The fabrication of high resolution patterns on InP-substrates by
focused ion beam implantation and selective wet chemical etching has
been investigated. InP acts as positive resist for Ga+ focused
ion beam exposure and development by HF. The values of contrast and
sensitivity have been determined to 12 and 1.5×1013 cm-2, respectively. By this technique short period line gratings with a linewidth of 30 nm have been fabricated.
Development of An Accurate Optical Proximity Correction System for 1 Gbit Dynamic Random Access Memory Fabrication
Authors: Sachiko Kobayashi Sachiko Kobayashi , Taiga Uno Taiga Uno , Kazuko Yamamoto Kazuko Yamamoto , Satoshi Tanaka Satoshi Tanaka , Toshiya Kotani Toshiya Kotani , Soichi Inoue Soichi Inoue , Hitoshi Higurashi Hitoshi Higurashi , Susumu Watanabe Susumu Watanabe , Mitsuhiro Yano Mitsuhiro Yano , Shinichiro Ohki Shinichiro Ohki , Kiyoshi Tsunakawa Kiyoshi Tsunakawa
Published: October 2002

In this paper, we demonstrate the feasibility of a refined one-dimensional (1D) optical proximity correction (OPC) method incorporated into a hierarchical mask data processing system. The correction accuracy was examined using experimental and lithography simulation by application to test patterns of a 1 Gbit dynamic random access memory (DRAM) metal layer. In the case of the 0.16 µm rule, the standard deviation of the refined 1D OPC was reduced to 9 nm, which is 70% of the standard deviation of 13 nm of the conventional 1D OPC method. The proposed OPC system, using an engineering workstation, succeeded in correcting the metal layer in a miniature model of a 1 Gbit DRAM within 2-4 days. Well-designed hierarchical management in the mask data processing system suppressed mask data volume expansion to within 4% compared to the data volume without OPC. These results suggest that the refined 1D OPC method is useful for the correction of 1 Gbit and future DRAM devices.
Pragmatical Asymptotical Stability Theorem with Application to Satellite System
Authors: Ge Zheng-Ming , Yu Jung-Kui , Chen Yu-Tzong
Published: October 2002

The motion stability of many actual dynamical systems may not be mathematical asymptotical stability in tradition, but it is actual asymptotical stability, namely, pragmatical asymptotical stability, which can be introduced by the concept of probability. To fill the gap between the tradictional idealized mathematical models and the actual reality of dynamical systems, a pragmatical asymptotical stability theorem is given with application to satellite system.
Composition Dependence of Inhomogeneous Hydrogen Bonding Structures in a-SiGe:H
Authors: Terakawa Akira , Matsunami Hiroyuki
Published: October 2002

Local hydrogen bonding configurations in hydrogenated amorphous
silicon germanium (a-SiGe:H) alloys fabricated by rf plasma chemical
vapor deposition were systematically investigated by means of IR
absorption spectroscopy with relating to the compositions. The H
bonding configurations around Si in a-SiGe:H are quantitatively
equivalent to those in a-Si:H. It was suggested that the
deteriorating alloying property is partly due to the increase in the
Si–H2 content with increasing H content bonding to Si per Si atom (C
H(Si)). The
C
H(Si) has positive
correlations to both the H content (C
H) and Ge content
(C
Ge), while the H content bonding to Ge per Ge atom
(C
H(Ge)) is almost constant at 2–4 at.%. As a result,
the preference of H attachment to Si over Ge has positive correlations
to both C
H and C
Ge. The origin of the
composition dependence of the preferential attachment is attributable
to the H-elimination kinetics during film growth.
Optimization of Al-doped ZnO Window Layers for Large-Area Cu(InGa)Se2-Based Modules by RF/DC/DC Multiple Magnetron Sputtering
Authors: Cooray Nawalage F. , Kushiya Katsumi , Fujimaki Atsushi , Okumura Daisuke , Sato Masao , Ooshita Mineo , Yamase Osamu
Published: October 2002

In this report, a comparative study of physical properties of
the multilayered ZnO:Al films prepared by a combination of RF and DC
magnetron sputtering is presented. It has been found that a RF/DC/DC
trilayered system consisting of a thin RF-sputtered ZnO:Al bottom
layer with two identical DC-sputtered ZnO:Al layers deposited with a
low DC current improved the physical properties when compared to those
of the ZnO film of the baseline condition, [DC(2.0 A, thickness of
about 6500 Å) monolayer]. The sheet resistance and transmittance
of the highest quality ZnO film deposited with the
RF(600 Å)/DC(1.2 A, thickness of 4200 Å)/DC(1.2 A, thickness
of 4200 Å) sputtering condition were found to be
10 Ω/sq and 85% in the wavelength range of 350–1400 nm,
respectively. With the newly improved transparent-conductive-oxide
(TCO) window, Cu(InGa)Se2 (CIGS) modules (aperture area = 50 cm2)
have been fabricated, and marked improvement in fill
factor (FF) (+8%) and efficiency (+12%) have been obtained
when compared to those of the ZnO:Al deposited under the baseline
condition. The average efficiency of the above CIGS modules was found
to be 11.1%.
Millimeter Wave Harmonic Mixing in Thin-Film YBa2Cu3O7-x Josephson Junctions
Authors: Yasuoka Yoshizumi , Nozue Takashi , Yamashita Tsutomu
Published: October 2002

Harmonic mixing characteristics in thin-film YBa2Cu3O7-x
(YBCO)
Josephson junctions fabricated using photolithography were examined at the liquid nitrogen temperature (77 K) using 94 GHz millimeter wave radiation. As a result, a mixing signal (IF output) was obtained up to the harmonic number of 55 in harmonic mixing using the local oscillation (LO) wave as the microwave. The output strongly depended on the power of the LO and signal waves, and on the Shapiro step spacing induced by the LO wave. The IF output decreased in proportion to N
-2 in the lower harmonic number region. However, the rate of decrease increased with an increase in the harmonic number.
Micromagnetic Structure Analysis of Head-on-Head-Type 180° Domain Wall in Submicron Size Co Wires
Authors: Nozaki Yukio , Matsuyama Kimihide , Ono Teruo , Miyajima Hideki
Published: October 2002

Micromagnetic structures of the 180° domain wall in submicron-size ferromagnetic Co wires
were investigated by means of magnetic force microscopy. The domain wall width δ (∼µm) observed in the Co wire is about 10 times larger than that observed in Co films of the same
thickness. From micromagnetic calculations using the Landau-Lifshitz-Gilbert (LLG) equation, the magnetic structure of the 180° domain wall is expected to be a large vortex accompanied by a magnetic ripple structure. This complicated 180° domain wall is formed to reduce the demagnetizing energy due to a head-on-head configuration of the magnetization,
which results in a micron-scale transition area of the domain wall. The wire width dependence of the 180° domain wall width obtained by micromagnetic calculations is almost consistent with that measured from the magnetic force micrograph.
Time Domain Study on Cavity Ring-Down Signals from a Fabry-Pérot Cavity under Pulsed Laser Excitations
Authors: Yong Lee Jae , Won Hahn Hai-Woong Lee
Published: October 2002

We present an analysis on ring-down signals produced by a pulsed laser excitation of a Fabry-Pérot cavity. Main features of a ring-down signal are numerically investigated by taking time domain approach under a simplistic assumption that a Fourier-transform-limited Gaussian laser pulse be injected to a stable empty cavity with complete mode-match to the lowest cavity transverse mode. Temporal aspects and output coupling efficiency of a ring-down signal are obtained with excitation pulse duration and cavity parameters taken into account. Clear physical insight is allowed in the time domain description especially for the forefront transient peak and the inherent intensity modulation which are found to be superimposed on a ring-down signal.
Dynamic Behavior of Stimulated Brillouin Scattering in a Single-Mode Optical Fiber
Authors: Li Hongpu , Ogusu Kazuhiko
Published: October 2002

We theoretically and experimentally investigate the transient
stimulated Brillouin scattering (SBS) in a single-mode fiber. The
experiment was conducted using a single-mode pulsed YAG laser and
demonstrates that SBS can occur even in the nanosecond region. Due to
the transient nature of SBS, pulse narrowing of the transmitted pulse
is observed. The experimental results agree with the theory based on
the coupled-amplitude equations for the pump, Stokes, and acoustic
waves. The steady-state solution of SBS is obtained when the pulse
width of the incident pulse is one 100-fold greater than the
round-trip time within the fiber. We show that the instability of SBS
depends on the magnitude of the nonlinear refractive index of the
fiber. SBS instability behavior appears at different pump power levels
when the nonlinear refractive index is an order of magnitude larger
than that of the fused-silica fiber.
Chaotic Oscillation in a Single-Mode Class A He–Ne Laser (6328 Å) II
Authors: Fumiyoshi Kuwashima Fumiyoshi Kuwashima , Takesi Ichikawa Takesi Ichikawa , Iwao Kitazima Iwao Kitazima , Hiroshi Iwasawa Hiroshi Iwasawa
Published: October 2002

Chaotic oscillation in a single-mode He-Ne laser (6328 Å), which belongs to a class A laser, is investigated through experiments I which were reported in our previous paper [F. Kuwashima, I. Kitazima and H. Iwasawa: Jpn. J. Appl. Phys. 37 (1998) L325.], and the improved experiments II. The results of experiments II, which were conducted using a neutral density (ND) filter instead of the tilted mirror used in experiments I, demonstrate the effect of the tilted mirror and a pumping parameter on the chaotic behavior of this laser. We also confirm and discuss the threshold value for chaos vs control parameters from the estimated Lyapunov exponents. The route to chaos in this laser is also discussed. Lastly, the laser equation of the class A laser with delayed feedback is introduced and numerical results which reveal chaotic oscillations are reported.
Quantitative Measurement of Thermal Lens in Diode-Laser Pumped Self-Frequency-Doubled Nd,Lu:YAl3(BO3)4 Laser under Lasing and Non-Lasing Conditions
Authors: Shimosegawa Masayuki , Omatsu Takashige , Hasegawa Akira , Tateda Mitsuhiro , Ogura Iwao , Wang Pu , Dawes Judith M.
Published: October 2002

We present a quantitative comparison between thermal lenses
under lasing and non-lasing conditions in a diode-laser pumped
self-frequency-doubled Nd,Lu:YAl3(BO3)4 laser using an interferometric
technique. At the pump power of 1.5 W, the thermal lens under the non-lasing condition attained 8 m-1, and this corresponded to 170% of that
under the lasing condition. Validity of the measured thermal lenses was
confirmed by investigating the dependence of output power on the
cavity length. The difference between thermal lenses under lasing and
non-lasing conditions is caused by the nonradiative loss process of the
upper level due to the cross-relaxation.
Pulse Shaping of Ultrashort Laser Pulses with Nonlinear Optical Crystals
Authors: Zhang Tiejun , Yonemura Motoki
Published: October 2002

We present a detailed description of the pulse shaping of
ultrashort laser pulses with nonlinear optical crystals by introducing
a time delay between two fundamental pulses. We demonstrate that the
frequency reconversion process from a second-harmonic pulse to
fundamental pulses will play an important role in fundamental pulse
compression and train pulse generation. A collinear type II potassium
dihydrogen phosphate (KDP) crystal can be used to achieve complete
pulse shaping for a 1053 nm wavelength. Under conditions of a
50 GW/cm2 fundamental intensity, a 1.0 ps fundamental pulse
duration and a 0.7 ps delay time, the second-harmonic pulse can be
compressed to 0.14 ps. In addition, the fundamental pulse can be
compressed to 0.3 ps by introducing an intensity unbalance into the
two fundamental pulses. Furthermore, the train pulse can be generated
by increasing the fundamental intensity over 20 GW/cm2. A train
pulse with three 0.1 ps individual pulses with a 2.5 THz frequency
interval can be generated for a 100 GW/cm2 fundamental
intensity. We also demonstrate that pulse shaping with a noncollinear
type I BBO crystal can be achieved at wavelengths near 800 nm.
Holographic Video System using Fourier Transform and Data Reduction
Authors: Kim Sung-Kyu , Son Jung-Young , Chun Joo-Hwan , Lim Tong-Kun
Published: October 2002

A holographic video system, displaying Fourier-transform-based
computer-generated hologram (CGH) data is described. A
Fourier-transform-based horizontal-parallax-only (HPO) CGH is
basically a two-dimensional hologram. To expand a
Fourier-transform-based HPO CGH, a new algorithm based on the ray
tracing of a three-dimensional object is used. This algorithm can
reduce the amount of data and calculation time of the CGH. The result
of this algorithm is applied to a pulsed-laser holographic video
system for reconstruction of a three-dimensional object. The
experimental results are included; they show a good parallax image and
illustrate the possibility of reducing the amount of data and
calculation time of the CGH. An additional advantage of this system
over the Fresnel hologram CGH is described as well.
Influence of Sapphire Nitridation on Properties of Indium Nitride Prepared by Metalorganic Vapor Phase Epitaxy
Authors: Pan Yung-Chung , Lee Wen-Hsiung , Shu Chen-Ke , Lin Heng-Ching , Chiang Chung-I , Chang Horng , Lin Deng-Sung , Lee Ming-Chih , Chen Wei-Kuo
Published: October 2002

Indium nitride films have been successfully grown on (0001) sapphire
substrates by metalorganic vapor phase epitaxy (MOVPE) using TMIn and NH3
as source precursors. Experimental results indicated that pregrowth
treatments, such as buffer layer growth, nitridation temperature and
nitridation duration have dramatic effects on the growth of the InN films. For films
nitridated at 1,000°C for 40 min without any buffer layer growth,
we obtained an InN film quality with Hall mobility, carrier concentration
and line width of Raman E2 mode of 270 cm2/V·s, 5 ×1019 cm-3 and 4.5 cm-1, respectively, which is among the best
quality ever reported for such type of film grown by MOVPE.
Free Standing Sintered Ceramic Films from Electrophoretic Deposition
Authors: Basu Rajendra N. , Mayo Merrilea J. , Randall Clive A.
Published: October 2002

The fabrication of free standing ceramic films ∼10 µm has been demonstrated using electrophoretic deposition on a polished substrate with a fugitive graphite electrode. Electrophoretic deposition allows a homogeneous powder bed to be obtained with green densities ∼55 to 60% of theoretical density. The graphite interlayer first acts as the electrode and then on sintering is removed, therefore providing only a weakly bonded interface. The deposit undergoes sintering under unconstrained conditions, owing to the poor adhesion; then on cooling the thermal expansion mismatch leads to free standing films.
Dominant Overall Chemical Reaction in a Chlorine Trifluoride–Silicon–Nitrogen System at Atmospheric Pressure
Authors: Hitoshi Habuka Hitoshi Habuka , Toru Otsuka Toru Otsuka , Wei-Feng Qu Wei-Feng Qu
Published: October 2002

This study evaluates the overall chemical reaction in a chlorine trifluoride–silicon–nitrogen system at atmospheric pressure, based on the observation of the dominant chemical species in the gas phase using a quadrupole mass spectra analyzer coupled with a horizontal cold-wall single-wafer epitaxial reactor. Chlorine trifluoride gas etches the silicon surface, producing two major products, silicon tetrafluoride gas and chlorine gas, at room temperature and 530 K. The production of chlorosilanes was not observed in this study. The results obtained in this study indicate that the dominant overall chemical reaction in a chlorine trifluoride–silicon–nitrogen system is 3Si + 4ClF3 →3SiF4 ↑+ 2Cl2 ↑.
X-Ray Diffraction Studies of Epitaxial La0.5Sr0.5CoO3 Thin Films Prepared by the Dipping-Pyrolysis Process
Authors: Hwang Kyuseog , Lee Hyungmin , Ryu Hyunwook , Lim Yongmu , Yamaguchi Iwao , Manabe Takaaki , Kumagai Toshiya , Mizuta Susumu
Published: October 2002

A reciprocal-space map (ω–2θ scans) can provide more information than conventional X-ray diffraction (XRD) θ–2θ scans. In this study, an epitaxial La0.5Sr0.5CoO3 thin film prepared on the SrTiO3(100) substrate by the dipping-pyrolysis (DP) process was investigated based on XRD θ–2θ scanning, β scanning (pole figure) and asymmetric ω–2θ scanning. An epitaxial La0.5Sr0.5CoO3 film annealed at 800°C was found to consist of the pseudocubic phase with a d
∥/d
⊥ ratio of 1.005 by reciprocal-space map analysis.
Direct Observation of Deoxyribonucleic Acid Anchored between an Aluminum Electrode and an Atomic Force Microscope Cantilever
Authors: Masanori Ueda Masanori Ueda , Yoshinobu Baba Yoshinobu Baba , Hiroshi Iwasaki Hiroshi Iwasaki , Osamu Kurosawa Osamu Kurosawa , Masao Washizu Masao Washizu
Published: October 2002

We investigated an electrostatic method for cross-linking long deoxyribonucleic acid (DNA) molecules between an electrode on a substrate and an atomic force microscope (AFM) cantilever. The cantilever was coated with aluminum and placed between aluminum electrodes fabricated on a glass plate, and an electric field was applied to the electrodes. We demonstrated that DNA molecules were stretched parallel to the field line, and immobilized between one of the electrodes and the AFM cantilever.
Effect of Donor Space Charge on Electron Capture Processes in Quantum Well Infrared Photodetectors
Authors: Maxim Ryzhii Maxim Ryzhii , Victor Ryzhii Victor Ryzhii , Magnus Willander Magnus Willander
Published: October 2002

The effect of donor space charge on electron capture processes in AlGaAs/GaAs multiple quantum well infrared photodetectors (QWIPs) is studied using an ensemble Monte Carlo (MC) particle modeling. It is shown that the corrugation of the conduction band edge due to donor charges in the inter-QW barriers strongly influences the electron distribution over energies and the electric-field dependence of the electron capture rate. Vertical nonuniformity of the donor distributions in QWs results in an asymmetry in the electric-field dependence of the capture parameter. This effect can essentially contribute to the asymmetry in the QWIP current-voltage characteristics in the dark condition and under illumination.
Surface Phonons, Electronic Structure and Chemical Reactivity of Diamond (100)(2 ×1) Surface
Authors: Hossain Md. Zakir , Kubo Toshitaka , Aruga Tetsuya , Takagi Noriaki , Tsuno Takashi , Fujimori Naoji , Nishijima Mitsuaki
Published: October 2002

Surface phonons, electronic structure and chemical reactivity of the diamond (100)(2 ×1) surface have been studied using electron energy loss spectroscopy (EELS), thermal desorption spectroscopy (TDS) and low-energy electron diffraction (LEED). Vibrational losses are observed at ∼80, 92, 123, 135, 147 and 165 meV for a clean C(100)(2 ×1) surface. The 92 meV loss is assigned to the in-phase bouncing mode of the surface dimers. The origins of the other losses are discussed. Electronic transition is observed at 3.5 eV which is associated with the interband transition between the π and π* surface states. The chemical reactivity of the C(100)(2 ×1) surface towards several gases, H, H2, O, O2, CO, N2O and C2H2, has been investigated at 90 and 300 K. The chemical reactivity of the C(100)(2 ×1) surface towards these gases is compared with that of the Si(100)(2 ×1) surface, and the origin of the difference in the reactivity is discussed.
Slot Antenna Coupled YBa2Cu3O7-δ Josephson Mixers for Millimeter Wave Radiation
Authors: Hasegawa Akihisa , Uchida Takashi , Yasuoka Yoshizumi
Published: October 2002

The antenna structure and the direction of the irradiated signal wave were
investigated in order to improve the responsivity of a slot antenna coupled
YBa2Cu3O7-δ (YBCO) Josephson mixer. The slot antenna coupled Josephson mixer
consists of a thin-film slot antenna on a fused quartz substrate and a YBCO
Josephson junction on a MgO substrate. It was found that maximum
responsivity was obtained by letting the thickness of the MgO substrate be odd
multiples of λd/4 (λd: wavelength in the substrate) and irradiating the
electromagnetic wave through the MgO substrate. Furthermore, the device with the optimized structure improved the responsivity in the third-harmonic mixing
by 7 dB compared to the device without a slot antenna in the harmonic
mixing at 48 GHz.
Magnetization Reversal in Patterned Permalloy Single Domain Elements
Authors: Wu Jong-Ching , Huang Ying-Wen , Huang Hong-Wen , Wu Te-ho
Published: October 2002

This paper presents magnetization reversal in patterned single domain magnetic elements. The experimental setup consisted of elliptical permalloy elements produced on top of a pre-formatted gold strip. The external magnetic field was applied through the permalloy elements by passing electrical current through the gold strip. Magnetic force microscopy images of the patterned elements after various electrical currents were applied demonstrated the magnetization reversal.
Ultrathin-film Local Oscillator for Determination of Complex Components of Second-Order Nonlinear Susceptibility
Authors: Kajikawa Kotaro , Sei Masaki , Yoshida Itsuki , Okada Shuji , Nakanishi Hachiro , Seki Kazuhiko , Ouchi Yukio
Published: October 2002

The second-harmonic generation (SHG) interferometry technique has to date been used
to determine the phase of second-harmonic (SH) light generated in a single polarization
combination of a polarizer and an analyzer. However, it is not easy to compare phases of the
SH light generated by a plural polarization combination, because a thick local oscillator, such
as an α-quartz single crystal, has several disadvantages for this purpose. The birefringence
and optical rotatory power of the quartz crystal often require further consideration on the
phase relation of the SH lights with different polarizations. Thus, the full determination of
the complex χ-components of an organic ultrathin film by the use of the quartz crystal is
impractical. After surveying SH active systems, we found that a 2-docosylamino-5-nitropyridine (DCANP) Langmuir-Blodgett (LB) film is the most applicable for the phase
measurements. A few nanometers-thick DCANP LB film,
which is much thinner than the
wavelength of the SH light, yields a negligible phase delay even if birefringence is present.
The SHG efficiency of the film can be easily controlled by changing
the number of layers.
Some experimental results are addressed to demonstrate the advantage
of the DCANP LB
film as a local oscillator.
Performance Improvement of a Discharge-Pumped ArF Excimer Laser by Xenon Gas Addition
Authors: Kataoka Naoki , Itagaki Motoya , Uchino Kiichiro , Muraoka Katsunori , Takahashi Akihiko , Okada Tatsuo , Maeda Mitsuo , Hori Tsukasa , Terashima Katsutomo , Sumitani Akira , Enami Tatsuo , Mizoguchi Hakaru
Published: October 2002

The effect of xenon (Xe) gas addition to a discharge-pumped ArF excimer laser was examined. When the partial pressure of the Xe gas was changed over a wide range, the output energy of the ArF excimer laser was found to become maximum at the Xe partial pressure of 20 mTorr and to be about three times higher than that without Xe addition. It was shown that Xe gas addition was effective in increasing the initial electron density which was produced in the preionization process, and that the increase of the initial electron density then produced a tendency to make the main discharge in the laser uniform in the direction of the optical axis.
Electrooptic Response of Reflective-Mode, π/4-Twisted-Nematic Liquid Crystal Cell in the Voltage Regions Close to and Distant from the Freedericksz Transition Threshold
Authors: Lee Geon Joon , Kim Sang Hyuck , Jo Jae Cheol , Lim Tong Kun , Yoon Jae Sun , Kwon Soon Bum
Published: October 2002

Two reflective-mode, π/4-twisted-nematic liquid crystal
cells were prepared using E7 and ZLI 4801-000 liquid crystals and
their electrooptic responses were measured in the voltage regions
close to and distant from the Freedericksz transition threshold. Our
reflectivity data distant from the threshold voltage (V
th)
could not be described by the model that assumed a linearized
distribution of the twist angle across the cell and considered the
voltage dependency of the tilt angle to follow the equation suggested
by Lu and Saleh [Appl. Opt. 30 (1991) 2354], although the
fit is good near V
th. We determined that the reflectivity
in the voltage region distant from V
th should be
calculated using the model that considers the distributions of the
tilt angle and the twist angle. The director-axis distributions were
obtained from the numerical integration of the Ericksen-Leslie
equation.
High Density Data Recording on Thermally Addressable Liquid Crystal for Three-Dimensional Holographic Display
Authors: Inoue Tetsuhiko , Mikoshiba Shigeo
Published: October 2002

A high density data recording technique is investigated using a thermally addressable
smectic A liquid crystal panel in order to obtain three-dimensional (3D) images using the
holographic technique. An overwrite technique has been developed to obtain a high resolution.
The optimum peak power for an IR write laser beam is found to be 15 mW with a pulse
frequency of 10 kHz and a pulse duty of 60%. A horizontal spatial frequency of 333 line-pairs
per mm (corresponding to a 1.5 µs pixel pitch) is obtained with a diffraction efficiency of 1%.
The diffraction efficiency becomes as high as 18% when the maximum spatial frequency is
reduced to 62.5 lp/mm.
Optical Measurement of a Refractive Index for Large Sphere via Scattering
Authors: Yi Soung-soo
Published: October 2002

A simple method is demonstrated to determine the index of refraction of dielectric spheres by observing the scattering of visible light. Theoretical calculations show that there is an approximately linear relationship exists between the size parameter x=k
a=2πn
1
a/λ of the scattering sphere and the number of maxima and minima in the scattered field as a function of angle when the size parameter in the 6000–12000-region.
Time-of-Flight Photocarrier Mobility in Langmuir-Blodgett Films of Regioregular Poly(3-hexylthiophene)
Authors: D. Malhotra Bansi , S. Pandey Wataru Takashima , Rahul Singhal Rahul Singhal , Ken Endo Ken Endo , Masahiro Rikukawa Masahiro Rikukawa , Keiichi Kaneto Keiichi Kaneto
Published: October 2002

Time-of-flight (TOF) measurements are conducted in annealed (50°C) Langmuir-Blodgett (LB) films of chemically prepared regioregular 33.5% undoped poly(3-hexylthiophene) (P3HT) mixed with 66.5% stearic acid. The characterization of these poly(3-hexylthiophene)-stearic acid (P3HT-SA) films is accomplished using scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible analyses. The value of the TOF photocarrier mobility obtained in P3HT-SA LB film sandwiched between metal (Al) and indium-tin-oxide (ITO) glass is experimentally determined as 1.8×10-5 cm2/Vs at an applied field of 1.3×106 V/cm.
Effect of Ozone Annealing on the Charge Trapping Property of Ta2O5–Si3N4–p-Si Capacitor Grown by Low-pressure Chemical Vapor Deposition
Authors: Kato Hiromitsu , Seol Kwang Soo , Fujimaki Makoto , Toyoda Takehiko , Ohki Yoshimichi , Takiyama Makoto
Published: October 2002

The effect of ozone annealing on the charge trapping property of Ta2O5/Si3N4/p-Si
capacitors was examined by measuring high-frequency capacitance-voltage and thermally
stimulated current characteristics. The results suggest that two types of electron traps exist in
the Ta2O5 layer and that the ozone annealing efficiently eliminates
them.
Delta-Doping of Si in GaN by Metalorganic Chemical Vapor Deposition
Authors: Kim Jong-Hee , Yang Gye Mo , Choi Sung Chul , Choi Ji Youn , Cho Hyun Kyung , Lim Kee Young , Lee Hyung Jae
Published: October 2002

Si delta-doping in the GaN layer has been successfully demonstrated by metalorganic chemical vapor deposition. From the capacitance-voltage measurement, a sharp carrier concentration profile with a full width at half-maximum of 4.1 nm has been achieved with a peak concentration of 9.8×1018 cm-3. Si delta-doping concentration increases and then decreases with an increase in delta-doping time, and the use of a post-purge step in the ammonia ambient reduces Si delta-doping concentration. This indicates that delta-doping concentration is limited by the Si desorption process due to high growth temperatures.