bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison between Static and Dynamic Simulations of Ion Reflection and Sputtering from Layered Materials
Authors: Kawakami Retsuo , Ohya Kaoru
Published: October 2002

Using the computer simulation program EDDY, a comparison between static and dynamic simulations of ion reflection and sputtering from layered materials is made. The D+ ion bombardment of a carbon-layered tungsten bulk material and vice versa serves a model for layered materials. To make the comparison, the influence of the deposition layers on the emission processes is described. The static simulation, which does not allow atomic composition changes in solids, gives a rapid change of such emissions owing to an increase in the thickness of the layers. Such a phenomenon is suitable for the dynamic simulation of W-layered C because of smaller erosion and recoil implantation into the bulk for the W layer. For C-layered W, the dynamic simulation results show gradual changes due to larger erosion and recoil implantation of the C layer. For this reason, the thin C layer has a weak effect on the reflection coefficient and the sputtering yield of the bulk.
Transmissivities of Radiation Beams and Particle Beams in Multicomponent Mixed Materials: II. Finite Markov Chain Model
Authors: Tsuji Ryusuke , Suzuki Masahiro , Fujii Kan-ichi
Published: October 2002

This paper is a complement to an earlier paper [Jpn. J. Appl. Phys. 35 (1996) 4793] on the transmissivity of beams in multicomponent mixed materials of identical grain size and presents an analytical expression of transmissivity based on the finite Markov chain in the case of mixed materials of different grain sizes. The expression is represented by the flux vector and the response matrix obtained from the transition matrix.
Measurement of Force of Bow Holding and Contact Force between Bow Hair and String in Violin Playing by Pressure Measuring Film
Authors: Matsutani Akihiro
Published: October 2002

The force of bow holding and the contact force between bow hair and string in violin playing were measured by a pressure measuring film for the first time. It was scientifically identified that relaxed bowing was important for achieving a good violin tone. The proposed measurement manner may be helpful for objective evaluation of the bowing skill of amateur violinists.
Preparation of Lead Zirconate Titanate Thick Films by Arc-Discharged Reactive Ion-Plating Method
Authors: Yasuda Yoshiaki , Akamatsu Masahiro , Tani Masanao , Yoshida Makoto , Kondo Ken-ichi , Iijima Takashi
Published: October 2002

Lead zirconate titanate (PZT) thick films of 1 to 3 µm thickness were prepared by an arc-discharged reactive ion-plating (ADRIP) method. Each PZT thick film had a columnar dense structure. The films showed a perovskite single phase without any thermal treatment after deposition. A high plasma density of the arc discharge enabled a high deposition rate of more than 3 µm/h. The relative dielectric constant (ε
r) of the PZT thick films with the Zr/Ti=53/47 composition was about 2000. This value was almost equivalent to that of PZT bulk ceramics. The films typically showed well-saturated P-E hysteresis curves with the remanent polarization (P
r) of 44 µC/cm2 and the coercive field (E
c) of 39 kV/cm. The butterfly-shaped property of the displacement curve, which is caused by the bending motion in the vertical direction on the film surface, was also observed. Furthermore, the PZT thick films with the (100)-dominant orientation could be obtained by depositing them onto (100)-preferred PZT thin layers which were prepared by a chemical solution deposition (CSD) process.
Microstructure and Electrical Properties of Lead Zirconate Titanate Thin Films Deposited by Excimer Laser Ablation
Authors: Wang Zhan-Jie , Maeda Ryutaro , Ichiki Masaaki , Kokawa Hiroyuki
Published: October 2002

Thin films of Pb(Zr0.52Ti0.48)O3 (PZT) were prepared by excimer laser ablation on a Pt/Ti/SiO2/Si substrate and were crystallized by subsequent annealing at 750°C for 90 min. Crystalline phases in the PZT films were investigated by X-ray diffraction analysis. The microstructure and composition of the films were studied by transmission electron microscopy and energy dispersive X-ray spectroscopy, respectively. It is found that the films consist almost entirely of the perovskite phase, but a thin layer of the pyrochlore phase exists at the surface of the films. Electrical properties of these films were evaluated by measuring P–E hysteresis loops and dielectric constants. The remanent polarization and the coercive field of the films were 23.9 µC/cm2 and 60.5 kV/cm, respectively, while the dielectric constant and loss values measured at 1 kHz were approximately 950 and 0.04, respectively. The effect of the microstructure on the electrical properties of the PZT thin films is discussed.
Sol-Gel Derived Ferroelectric Pb(Zr1-xTix)O3–SiO2–B2O3 Glass-Ceramic Thin Films Formed at Relatively Low Annealing Temperatures
Authors: Wang Xusheng , Ishiwara Hiroshi
Published: October 2002

Ferroelectric PZT(PbZr0.52Ti0.48O3)–5 mol%SiO2–1 mol%B2O3 glass-ceramic thin films were fabricated by sol-gel and rapid thermal annealing (RTA) techniques on Pt/Ti/SiO2/Si(100) substrates at a relatively low annealing temperature of 650°C. The perovskite-phase PZT crystallites grew in the films and were preferentially oriented in the (111) direction. The PZT crystallization temperature was lower in the PZT–SiO2–B2O3 system, compared to that in PZT–SiO2 and pure PZT. The dielectric constant and loss, remnant polarization, and leakage current of the films annealed at temperatures ranging from 650 to 700°C were lower than those of pure PZT.
New Fatigue Model Based on Thermionic Field Emission Mechanism
Authors: Tajiri Masayuki , Nozawa Hiroshi
Published: October 2002

We investigated the mechanism of the fatigue phenomenon in ferroelectric thin films such as Pb(Zr, Ti)O3 (PZT) and SrBi2Ta2O9 (SBT). The fatigue phenomenon in PZT was successfully explained by a new concept model introducing the effect of impact-ionization and energy distribution of trap levels to thermionic field emissions. This model can also explain the effect of applied voltage and temperature on the fatigue phenomenon. Moreover, we can simulate the fatigue characteristics in SBT by including the energy dissipation effect on the model for PZT. By introducing this result into an extrapolation method, the rewriting limit of ferroelectric thin films can be successfully predicted.
Synthesis and Properties of Highly Oriented (Sr, Ba)(Nb, Ta)2O6 Thin Films by Chemical Solution Deposition
Authors: Sakamoto Wataru , Horie Yu-saku , Yogo Toshinobu , Hirano Shin-ichi
Published: October 2002

Transparent and highly oriented (Sr, Ba)(Nb, Ta)2O6 (SBNT) thin films have been synthesized by a chemical solution deposition method. A homogeneous and stable SBNT precursor solution was prepared by controlling the reaction of metal alkoxides in solution and by optimizing the additive as a stabilizing agent. Tantalum-substituted (Sr0.5Ba0.5)Nb2O6 powders and thin films, such as (Sr0.5Ba0.5)(Nb0.5Ta0.5)2O6 (SBNT50/50) and (Sr0.5Ba0.5)(Nb0.8Ta0.2)2O6 (SBNT50/80), directly crystallized into the tetragonal tungsten bronze phase at 700°C. The synthesized SBNT thin films on MgO(100) and Pt(100)/MgO(100) had a prominent c-axis-preferred orientation. Two crystal lattice planes of SBNT were found to intergrow at an orientation of 18.5° on MgO(100) and Pt(100)/MgO(100) substrates by X-ray pole figure measurement. The SBNT50/80 and SBNT50/50 thin films on Pt(100)/MgO(100) were paraelectric at room temperature and showed diffuse phase transition of the ε-T curves.
Fabrication and Electrical Characteristics of a Trench-Type Metal-Ferroelectric-Metal-Insulator-Semiconductor Field Effect Transistor
Authors: Sakamaki Kazuo , Migita Shinji , Xiong Si-Bei , Ota Hiroyuki , Sakai Shigeki , Tarui Yasuo
Published: October 2002

We describe a new type of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) memory transistor. This offers a clear advantage in term of device size, and is thus suited for future high-density integration of memory. The MIS transistor of the MFMIS structure is formed along the sidewall of a trench, and the MFM capacitor is formed just over the trench, whereby small device size is realized. We fabricated a test device. The gate insulator in the trench was 14-nm-thick SiO2. In the trench, poly-Si was filled and a 200-nm-thick IrO2 layer was deposited on it. This stack of poly-Si and IrO2 functions as the intermediate metal layer. A 500-nm-thick SrBi2Ta2O9 ferroelectric film was formed by the laser ablation technique. A platinum film was deposited as the top electrode. The drain current-gate voltage characteristics of this test device showed the desired a threshold hysteresis curve whose memory window was about 4.5 V for a voltage swing between -4 V and 8 V.
Ferroelectric Properties of (Ag, Li)(Nb, Ta)O3 Ceramics
Authors: Sakabe Yukio , Takeda Toshikazu , Ogiso Yoshifumi , Wada Nobuyuki
Published: October 2002

The composition of (Ag1-y
Li
y
)(Nb1-x
Ta
x
)O3 ceramics has been investigated by X-ray analysis and dielectric measurement. Li1+ was substituted into the Ag1+ lattice site of Ag(Nb, Ta)O3 ceramics. The solubility limit of Li2O in Ag(Nb, Ta)O3 was estimated to be in the range from 10 to 15 mol%. The crystal phase and dielectric properties of the (Ag1-y
Li
y
)(Nb1-x
Ta
x
)O3 ceramics significantly changed with Li and Ta concentrations. The crystal phase changed from rhombohedral to monoclinic, tetragonal and cubic with temperature. Strong ferroelectricity was observed via
D-E hysteresis measurement, and remanent polarization P
r=23 µC/cm2 and coercive field E
c=22 kV/cm were obtained.
Grain Size Dependence of Third Nonlinear Piezoelectric Coefficient in Lead Zirconate Titanate Ceramics
Authors: Tashiro Shinjiro , Murata Toshiro , Ishii Keisuke , Igarashi Hideji
Published: October 2002

Piezoelectric Lead Zirconate Titanate (PZT) ceramics with different grain sizes were fabricated by changing the firing conditions. Using these samples, the grain size dependence of the third nonlinear piezoelectric coefficient in the transverse direction, ξ
D31, was experimentally investigated. The ξ
D31 decreased with the increase of grain size. This decrease of ξ
D31 was assumed to be caused by the promotion of poling in the samples with large grains. In order to demonstrate this fact, poling field dependence and MnO additive dependence of ξ
D31 were investigated. From the results of these three items of dependence, we concluded that the nonlinear motion of residual domain walls in poled samples exerts a large influence on the ξ
D31 value.
Observation of Piezoelectric Relaxation in Ferroelectric Thin Films by Continuous Charge Integration
Authors: Desheng Fu Desheng Fu , Kenji Ishikawa Kenji Ishikawa , Makoto Minakata Makoto Minakata , Hisao Suzuki Hisao Suzuki
Published: October 2002

A continuous charge integration technique is used to measure the effective longitudinal piezoelectric coefficient (d
33) of thin films. Measurements are performed by applying a static force normal to the films and recording the stress-induced polarization with a charge integrator. Measurements for the as-deposited PbZr0.53Ti0.47O3 (PZT) thin films show that the piezoelectric effect is strongly time-dependent and the relaxation is well described by the stretched exponential law. It was demonstrated that the continuous charge integration technique is highly useful for the characterization of the piezoelectric properties of thin films.
Fabrication of Ultrasonic Transducers with KNbO3 Piezoelectric Single Crystal for Detecting Harmonic Signals
Authors: Adachi Hideo , Wakabayashi Katsuhiro , Nishio Masahiro , Ogawa Haruo , Kamakura Tomoo
Published: October 2002

An ultrasonic transducer with a circular aperture has been designed and fabricated for the development of a harmonic imaging system with high sensitivity. The transducer consists of two piezoelectric elements; one is made from Pb(Zr, Ti)O3 (PZT) ceramics for transmitting a finite-amplitude ultrasonic pulse, and the other is made from a KNbO3 (KN) piezoelectric single crystal for receiving second harmonic signals generated in a nonlinear medium. They are arranged coaxially. Using this transducer, acoustic characteristics were measured and the observation of sponge phantom images was performed. Compared with other transducers with PZT and PbTiO3 (PT) ceramics, we have confirmed that higher sensitivity and stronger correlation between the sensitivity and figure-of-merit can be obtained. Additionally, the third harmonic detection has been demonstrated.
Crystal Growth and Electrical Properties of Lead-Free Piezoelectric Material (Na1/2Bi1/2)TiO3–BaTiO3
Authors: Hosono Yasuharu , Harada Kouichi , Yamashita Yohachi
Published: October 2002

Single crystals of lead-free piezoelectric material x(Na1/2Bi1/2)TiO3–yBaTiO3 (NBBT 100x/100y) have been successfully grown by the flux method and the Bridgman method. Using the flux method, crystals having an edge length of 2–8 mm were obtained using Bi2O3 flux with cooling from 1350°C to 800°C at a rate of 3.5°C/h. Using the Bridgman method, comparatively good crystal of 15 mm diameter and 50 mm length was obtained using Bi2O3 flux with the Pt crucible driven down through the heat zone at a speed of 1.0 mm/h. The resulting crystals showed single-phase perovskite structure. Inductively charged plasma (ICP) chemical analysis revealed that the composition of the pulverized powder of these crystals is NBBT 97/3, which is slightly different from the charged composition of NBBT 94/6. One of the single crystals grown by the Bridgman method showed a dielectric constant of 1230 at room temperature and a dielectric constant peak at 313°C.
Dielectric Properties of Crystallization Process from Amorphous Bi4Ti3O12
Authors: Masaaki Takashige Masaaki Takashige , Sinichi Hamazaki Sinichi Hamazaki , Ryou Yoshida Ryou Yoshida , Masayoshi Kokubun Masayoshi Kokubun , Fuminao Shimizu Fuminao Shimizu , Toshihisa Yamaguchi Toshihisa Yamaguchi , Min-Su Jang Min-Su Jang , Seiji Kojima Seiji Kojima
Published: October 2002

The dielectric constant of amorphous Bi4Ti3O12 prepared by a rapid quenching method was measured. It was found that the as-quenched sample shows a distinct dielectric anomaly at approximately 600°C. With further heating, the dielectric constant shows an anomalously high value above 750°C. In the sample heated to the 900°C range, the recovery of the ferroelectric Bi4Ti3O12 crystalline phase was confirmed by observing the dielectric anomaly at the Curie point.
Platinum Hillocks in Pt/Ti Film Stacks Deposited on Thermally Oxidized Si Substrate
Authors: Kweon Soon Yong , Choi Si Kyung , Yeom Seung Jin , Roh Jae Sung
Published: October 2002

The stress dependence of platinum hillock formation during post thermal cycling was investigated in Pt/Ti electrode stacks. Annealing temperatures were varied from room temperature (RT) to 650°C. High compressive stress was generated during electrode annealing by the Ti diffusion into the platinum layer followed by oxidation in the platinum grain boundaries. The compressive stress was the major driving force for the hillock formation on the platinum surface. Thus, the Ti glue layer was oxidized before platinum deposition to reduce the Ti diffusion. The Pt/TiO
x
electrode stack retained its smooth platinum surface after the electrode annealing of 650°C for 30 min in O2. The Pt/TiO
x
interface remained flat even after the ferroelectric annealing at 800°C, which was performed after SrBi2Ta2O9 (SBT) deposition. Moreover, the remanent polarization (2P
r) of the SBT capacitor was increased to 17 µC/cm2 on the Pt/TiO
x
electrode stack, up from 13 µC/cm2, which was the value on the Pt/Ti electrode stack.
Ordering InAs Quantum Dots Formation on GaAs/InP by Low Pressure Metal-Organic Chemical Vapor Deposition
Authors: Yin Yin , Jingzhi Jingzhi , Wang Wang , Xinqiang Xinqiang , Du Du , Guotong Guotong , Yin Yin , Zongyou Zongyou , Li Li , Mingtao Mingtao , Li Li , Zhengting Zhengting , Yang Yang , Shuren Shuren
Published: October 2002

In the paper, a thin tensile GaAs interlayer was used to get regular arrangement of InAs quantum dots (QDs) on InP substrate by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The characterizations of the InAs QDs have been investigated by Photoluminescence (PL) spectrum, atomic force microscopy (AFM) image and Raman spectrum. The theoretical calculations have been performed. The conclusions coincide with our experiment results well.
Characteristics of Deep Submicron Grooved-Gate P-Channel Metal-Oxide-Semiconductor Field-Effect Transistors
Authors: Ren Hongxia , Hao Yue , Xue Lei
Published: October 2002

Based on the hydrodynamic energy transport model, the electrical characteristics of grooved-gate p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) are studied and compared with those of corresponding conventional planar PMOSFETs. The simulations reveal that the short-channel effect and drain-induced barrier lowering (DIBL) are absent in grooved-gate PMOSFETs, which have good hot-carrier effect immunity, but the drain current driving capability is lower than that in planar ones. Subsequently, the reasons for these differences between grooved-gate and planar PMOSFETs are analyzed from the viewpoint of interior physical parameter distribution. These parameters include surface potential, electric field, hot-carrier velocity, temperature and so forth.
Chaotic Behaviors of Bistable Laser Diodes and Its Application in Synchronization of Optical Communication
Authors: Wang Weichung , Hwang Tsung-Min , Juang Cheng , Juang Jong , Liu Chin-Yueh , Lin Wen-Wei
Published: October 2002

Period-doubling routes to chaos behavior in bistable laser diodes is examined numerically. An external sinusoidal electronic drive is injected to generate chaotic light output. Phase portrait, Poincaré map, bifurcation diagram, and Lyapunov exponent are then calculated to assert the existence of chaos. Furthermore, according to Pecora and Carroll's theory, a drive-response system is constructed by using the bistable laser diodes to mask the sinusoidal electronic signal with chaotic light. Synchronization can be achieved for optical simplex and duplex transmissions using bistable laser diodes. The proposed synchronization scheme between two separate chaotic systems provides a key step toward optical chaotic communication.
Interfaces of Photonic Crystals for High Efficiency Light Transmission
Authors: Baba Toshihiko , Ohsaki Daisuke
Published: October 2002

Input and output interfaces of photonic crystals are discussed for high efficiency transmission of light. The discussion focuses on the frequency range higher than the photonic bandgap, at which a small group velocity of light, the superprism effect, the strong structural birefringence and the negative refractive index effect are expected. The two-dimensional photonic crystal of triangular lattice airholes in a high-refractive-index dielectric medium is assumed as the fundamental model. The finite difference time domain simulation shows that two types of interfaces improve the transmission efficiency. One is composed of small airholes and the other is composed of projected airholes. In particular, the latter generates a wide transmission band of ∼ 0.1 times the center frequency with the maximum efficiency of -0.01 dB against the normal or slightly inclined incidence of the TE-polarized wave.
Differential Method of Diode Laser Wavelength Stabilization
Authors: Zhmud' Alexander A.
Published: October 2002

This paper is devoted to a new kind of diode laser wavelength stabilization system based on the wedge interferometer. The absence of wavelength modulation is the main advantage of the proposed method.
Photoconductive Plastic Holography Employing White-Light Laser
Authors: Uno Katsuhiro , Mano Norihito , Saruta Koichi , Fujii Kan-ichi , Shimizu Isao , Tokita Yasuhiro
Published: October 2002

We have succeeded in quasi real-time holography engineering by using a photoconductive plastic (PCP) plate and in full-color holography engineering by employing a hollow-cathode type, He–Cd+, white-light laser. We have also succeeded in eliminating ghost images, which are inherent in holograms reconstructed from multiwavelength light, using diffused reference illumination.
Infrared-Cut Filter
Authors: Berezhinsky Leonid , Kwon Kwang-Ho , Park Byung-Sun
Published: October 2002

An infrared-cut filter for TV and video cameras was calculated and fabricated. The filter contains 29 alternating SiO2 and TiO2 layers. A real filter has a transmittance of 90% in the 400–650 nm range and 1% in the 700–1000 nm range.
Novel Polarized-Light Emitting Polymer Systems
Authors: Bastiaansen Natalie Stutzmann , Paul Smith Paul Smith
Published: October 2002

A novel, polymer bilayer illumination system is presented from which linearly polarized light is emitted. Separation of the two polarization directions is achieved by total internal reflection of the undesired light component at the polymer-polymer interface. Model systems comprising optically isotropic polystyrene (PS) sheets and oriented, birefringent poly(ethylene terephthalate) (PET) films with a relief structure to direct the light out of the systems displayed high polarizing capabilities: contrast ratios of over 10 for viewing angles between -10° and +20° were recorded in case of uncollimated incoming light. The use of a collimated light source resulted in contrast ratios of 20 up to over 40 over a viewing angle regime of -20° to +15°.
Pinning Effect by Interface States in Pr-type ZnO Varistors
Authors: Yasuhiro Ohbuchi Yasuhiro Ohbuchi , Toshio Kawahara Toshio Kawahara , Yoichi Okamoto Yoichi Okamoto , Jun Morimoto Jun Morimoto
Published: October 2002

The interface states in Pr-type ZnO varistors, which consist of two adjacent levels, T1 and T0, were studied using spectral analysis of deep-level transient spectroscopy (SADLTS) to characterize the pinning effect of the Fermi level by two interface states and the bias dependence on the emission process of the interface states. The measurements were carried out by changing the applied steady-bias voltage for the injection pulse. When the steady-bias voltage is below 60% of the breakdown voltage, the obtained values of the activation energy E
T and the capture cross section σ of the T1 level are almost constant. The Fermi level is perfectly pinned by the T1 level. In contrast, the Fermi level is never pinned by the T0 level since E
T and σ of the T0 level vary with increasing steady-bias voltage and the T0 level has a faster emission process.
New High Temperature Morphotropic Phase Boundary Piezoelectrics Based on Bi(Me)O3–PbTiO3 Ceramics
Authors: Eitel Richard E. , Randall Clive A. , Shrout Thomas R. , Rehrig Paul W. , Hackenberger Wes , Park Seung-Eek
Published: October 2002

New morphotropic phase boundary (MPB) piezoelectrics, with ferroelectric phase transition (T
c) exceeding that of PbZrO3–PbTiO3 (PZT), were investigated. Based on a perovskite tolerance factor-T
c relationship, new high T
c MPB systems were projected in the Bi(Me)O3–PbTiO3 system, where Me is a relatively large B+3-site cation. For the (1-x)BiScO3–(x)PbTiO3 solid solution, a MPB was found at x-0.64 separating the rhombohedral and tetragonal phases, with correspondingly enhanced dielectric and piezoelectric properties. A transition temperature T
c of ∼ 450°C was determined with evidence of T
c's on the order of ≥ 600°C in the BiInO3 and BiYbO3 analogues, though issues of perovskite stability remain for the smaller tolerance end-member systems.
Boundary Configuration of Heat-Treated Dauphiné Twin by X-Ray Topography and Computer Simulation
Authors: Masaaki Koga Masaaki Koga , Hiroshi Ninomiya Hiroshi Ninomiya , Tetsuo Yoshida Tetsuo Yoshida , Sigeru Oki Sigeru Oki
Published: October 2002

The configuration of the Dauphiné twin boundary, which was formed in the cooling process of the heat treatment of natural quartz with the β–α phase transition, was investigated by X-ray diffraction topography at room temperature and by computer simulation. Comparing the image from the section topograph of the Dauphiné twin wall with the image drawn by computer simulation, the part of the Dauphiné twin wall imaged by topography revealed a slight concave. It is concluded that the concave plane approximately corresponds to the envelope of the real boundary wall.
Scanning Tunneling Microscopy Study of the c(4×4) Structure Formation in the Sub-Monolayer Sb/Si(100) System
Authors: A. Saranin Alexander , V. Zotov Andrey , G. Kotlyar Vasiliy , G. Lifshits Victor , Osamu Kubo Osamu Kubo , Toru Harada Toru Harada , Tadashi Kobayashi Tadashi Kobayashi , Nobumitsu Yamaoka Nobumitsu Yamaoka , Mitsuhiro Katayama Mitsuhiro Katayama , Kenjiro Oura Kenjiro Oura
Published: October 2002

Upon Sb desorption from a Sb-saturated Si(100) surface, the c(4×4) structure formed at about 0.25 monolayer Sb coverage. The c(4×4) reconstruction has been found to develop best when the surface is slightly contaminated, plausibly, by carbon. The Si(100)-c(4×4)-Sb surface shows up in the high-resolution filled state scanning tunneling microscopy images as being very similar to that of the recently reported c(4×4)-Si reconstruction. Here the main features of the Si(100)-c(4×4)-Sb structure are identified and the possible atomic arrangement is discussed.
Epitaxial Film Growth of Au–Al Alloy on a Quasiperiodic Surface of Icosahedral Al72Pd19.5Mn8.5
Authors: Qing Guo Masahiko Shimoda , J Sato Taku , Pang Tsai An
Published: October 2002

We have found that an epitaxial film of Au–Al alloy can be formed on a quasiperiodic surface of icosahedral Al72Pd19.5Mn8.5. Depositions of Au onto the quasiperiodic surface, which is perpendicular to one of the fivefold axes of Al72Pd19.5Mn8.5, were attempted in order to create a quasicrystal of a single element as an epitaxial film. Although the desired film was not obtained on the clean surface, an ordered layer of Au–Al alloy with icosahedral symmetry was formed in the presence of predeposited In, which worked as a surfactant. X-ray photoelectron diffraction (XPD) images for Au 4f and Al 2s emissions from the ordered layer indicate clear fivefold symmetric patterns which are coherent with the symmetry of the substrate. In addition, symmetric elements specific to the icosahedral symmetry are clearly recognized in these patterns, indicating that both Au and Al atoms are located in an icosahedral environment with long-range bond-orientational order.
Atomic-Beam Propagation in a Two-Dimensional Standing Wave of Light: A Numerical Analysis Based on a Particle-Optics
Authors: Kenji Okamoto Kenji Okamoto , Yasushi Inouye Yasushi Inouye , Satoshi Kawata Satoshi Kawata
Published: October 2002

We study the propagation of an atomic beam flow in an optical potential generated by a two-dimensional (2D) standing wave produced by two interfering laser beams with a frequency that is close to the resonant frequency of the propagated atoms. We extended the equations of motion of an atom in a light field to three-dimensional (3D) coordinate system and calculated the 3D trajectories of chromium atoms that are thermally evaporated and deflected by the gradient force of the standing wave laser field. The polarization and polarity of detuning of the frequency of the interfering beams are varied to study the formation of chromium atoms on a substrate. Our results show that a combination of parallel polarization and positive detuning forms a 2D grid structure. The rest of the combination of polarization and polarity of detuning yields a 2D array of point structures. An optimum size of the point structure with a diameter of approximately 50 nm can be formed with an orthogonal polarization and positive detuning of the laser frequency.
Preparation of ZnO Thin Films Deposited by Plasma Chemical Vapor Deposition for Application to Ultraviolet-cut Coating
Authors: Anma Hidetaka , Yoshimoto Yuuji , Tanaka Mariko , Takatsuka Hiroyuki , Hatanaka Yoshinori
Published: October 2002

ZnO thin films coated on plastic materials were investigated for their use in the protection against solar ultraviolet (UV) radiation. Using diethylzinc (DEZ) as the organic source material, we attempted to deposit ZnO thin films on polycarbonate (PC) resin at room temperature by the cathode deposition technique of the capacitive-coupled radio frequency chemical vapor deposition (RFCVD) method. It was found that the ZnO films obtained were amorphous, and contained small quantities of CO and hydrocarbons, which decreased in the substrate temperature range above 75°C. In a xenon arc weatherability test, the ZnO-coated PC plates exhibited outstanding characteristics of UV protection, as they remained smooth and uncolored even after 1000 h of UV irradiation.
Treatment of Volatile Organic Compound by Positive Streamer Corona Using a Series Gap
Authors: Hayashi Nobuya , Suganuma Hideo , Kamatani Masaki , Satoh Saburoh , Yamabe Chobei
Published: October 2002

The nonthermal atmospheric pressure plasma produced by streamer corona discharge was used for the treatment of volatile organic compounds (VOCs). The decomposition rate of toluene as a VOC was investigated under various discharge conditions of discharge period, pulse rise time of discharge voltage and gas flow rate. The quantity of byproducts due to the toluene decomposition was controlled by the discharge parameter, that is, pulse rise time of discharge voltage applied between discharge electrodes.
New Photosensitive Polyimide System for Sealing High-Density Semiconductor Chip
Authors: Tajima Yusuke , Shigemitsu Yasuo , Takeuchi Etsu , Takeuchi Kazuo
Published: October 2002

A heat-resistant photosensitive polymer consisting of furan-substituted polyimide (FPI), and fullerene C60 as a photosensitizer has been developed. The FPI was cross-linked by a photo-oxidation-induced polycondensation (POP) reaction by means of the intervention of singlet oxygen generated from C60 triplet state photosensitization of oxygen molecules. Photochemical study using the laser flash photolysis method revealed that the C60 triplet state was quenched by FPI in solution. This phenomenon suggested a possibility that the POP reaction was hindered. However, in polyimide film, the effect of FPI on the quenching of the C60 triplet state was negligible. This is due to a fast diffusion rate of oxygen in polyimide film in comparison with the mobility of the FPI. It was shown by photolithographic evaluation that postexposure baking (PEB) enhanced the curing rate of the POP polyimide. Photolithography with PEB treatment at 120°C for 10 min is capable of boring pinholes of 10 µm diameter in a 12-µm-thick POP polyimide film. The thermostability of POP polyimide was found to be quite high, with the temperature needed to induce a 5% weight loss being higher than 370°C even without high-temperature annealing.
Influences of Various Metal Elements on Field Aided Lateral Crystallization of Amorphous Silicon Films
Authors: Lee Jae-Bok , Lee Chan-Jae , Choi Duck-Kyun
Published: October 2002

In this study, the effects of various metals on field aided lateral crystallization (FALC) behaviors of amorphous silicon (a-Si) were investigated. Under the influence of the electric field, some metals such as Cu, Ni and Co were found to induce the lateral crystallization toward the metal-free region while Au, Al and Cr were not able to induce the crystallization of a-Si. On the other hand, the effect of the electric field on the lateral crystallization was not obvious for Pd. These phenomenological differences could be interpreted in terms of the dominant diffusing species (DDS) in the reaction between the metal and Si. It is judged that the applied electric field can enhance the crystallization velocity by accelerating the diffusion of metal atoms because the occurrence of lateral crystallization is known to rely on the diffusion of metal atoms than that of Si atoms. Therefore, it is thought that the only metal-dominant diffusing species in the reaction between metal and Si can strongly result in the crystallization of a-Si in metal-free region.
A Chemical Mechanism for Determining the Influence of Boron on Silicon Epitaxial Growth
Authors: Maruno Shigemitsu , Furukawa Taisuke , Nakahata Takumi , Abe Yuji
Published: October 2002

The mechanism of dissociative adsorption of silane on nondoped Si(100)-(2×1) and boron-doped Si(100) substrates has been studied by an empirical quantum chemistry calculation method. It is found that the energy barriers on the reaction path for the boron-doped Si(100) are somewhat larger than those for the nondoped Si(100). Calculation of the desorption energy of hydrogen molecule from the hydride surfaces of these nondoped and boron-doped Si(100) substrates shows that B–B–H formation enhances the desorption energy compared with that in the nondoped Si(100). The calculation explains well our experimental studies on Si film growth kinetics by ultrahigh vacuum chemical vapor deposition with disilane as the source gas.
Spin Polarization Dependent Far Infrared Absorption in Ga1-xMnxAs
Authors: Yasuyuki Nagai Yasuyuki Nagai , Takashi Kunimoto Takashi Kunimoto , Keigo Nagasaka Keigo Nagasaka , Hiroyuki Nojiri Hiroyuki Nojiri , Mitsuhiro Motokawa Mitsuhiro Motokawa , Fumihiro Matsukura Fumihiro Matsukura , Tomasz Dietl Tomasz Dietl , Hideo Ohno Hideo Ohno
Published: October 2002

Infrared and far infrared transmission spectra have been measured for the ferromagnetic Ga1-x
MnxAs (x=0.034 and x=0.050) between 10 and 12000 cm-1. A broad peak is observed around 1600 cm-1, and this energy is close to the deep acceptor level of Mn impurity in GaAs. A finite featureless absorption, spreading between this peak and the band gap, due to inter valence band transitions is also observed. At the same time, a non-zero absorption is observed in the lowest frequency studied, which points to the absorption by mobile holes related to the metallic DC conductivity. The frequency dependence in this range, which differs markedly from the Drude model, demonstrates a strong influence of electrostatic and magnetic disorder on the optical conductivity. In particular, the existence of a strong coupling between the Mn spins and the holes explains the considerable increase of the far infrared absorption below the ferromagnetic ordering temperature.
Sb and Bi Passivation Effects on GaAs
Authors: Kuroda Nobuhiro , Ikoma Hideaki
Published: October 2002

Passivation effects of Sb and Bi on GaAs were investigated. Sb and Bi were vacuum-evaporated on GaAs (100) substrates. The Au/Sb/GaAs and Au/Bi/GaAs Schottky diode samples showed improved current-density–voltage (J–V) characteristics, in which the reverse leakage currents substantially decreased and the Schottky barrier heights increased, when the Sb-and Bi-layer thicknesses were appropriate (∼ 6 nm for Sb and ∼ 8 nm for Bi). X-ray photoelectron spectroscopic (XPS) and secondary ion mass spectroscopic (SIMS) data, together with the J–V characteristics, indicated that the passivation effects stem from the probable surface termination of GaAs with Sb and Bi, the removal of the native oxides of GaAs due to the reductive natures of Sb and Bi, and suppression of Au diffusion into GaAs by these layers. The GaN/GaAs structure was fabricated by the plasma nitridation of the Sb/GaAs sample in the helicon-wave excited N2 plasma.
Role of Substrate Temperature on the Properties of Microcrystalline Silicon Thin Films
Authors: Mukhopadhyay Sumita , Saha Subhas Chandra , Ray Swati
Published: October 2002

Hydrogenated silicon (Si:H) thin films were deposited in an ultrahigh vacuum system varying substrate temperature (T
s) from 200°C to 570°C, decomposing a gas mixture of monosilane-hydrogen, by a conventional (13.56 MHz) radio frequency plasma enhanced chemical vapor deposition (rf-PECVD) technique. A compact microcrystalline (µc) Si:H film has been developed at a deposition rate (R
d) of 25.1 Å min-1. The structural and bonding configurations were characterized by X-ray diffractometry and infrared (IR) vibrational spectroscopy. Growth processes are different for films deposited at low (T
s≈250°C) and high (T
s≥350°C) temperatures. In the films of low T
s, the planes (111) and (220), and polyhydrides are formed whereas, the growth of crystallites only along <220> and the monohydride formations are observed for the films deposited with high T
s. The dependence of both structural and optoelectronic properties on deposition temperature is discussed in terms of the growth kinetics and the properties are correlated.
Stress Release Behaviors of Amorphous SiC/Si Structure during Annealing
Authors: Yong Sun Yong Sun , Kyoichiro Nakatsugi Kyoichiro Nakatsugi , Tatsuro Miyasato Tatsuro Miyasato
Published: October 2002

An amorphous SiC/Si crystal structure is annealed at 950°C for 30 min in hydrogen gas atmosphere. Shrinkage of the amorphous SiC film during the annealing results in stress at the SiC/Si interface. Release behaviors of the stress depend on both the thickness of the film and the orientation of the Si substrate. When the stress is more than the fracture limits of the film and the substrate, release of the stress results in breaks in the SiC/Si structure. On the other hand, when the stress is smaller than one of the two fracture limits, no break occurs. If the fracture limit of the film is smaller than that of the substrate, the breaks are straight lines and their direction depends on the orientation of the substrate. Moreover, if the fracture limit of the film is more than that of the substrate, the breaks become curved. Also, the density of the breaks, length per unit area on the substrate, depends on shrinkage of the film and orientation of the substrate. The effects of residual oxygen in the substrate are also discussed.
Accurate Measurement of Spherical and Astigmatic Aberrations by a Phase Shift Grating Reticle
Authors: Nomura Hiroshi
Published: October 2002

A new grating structure is proposed for measuring aberrations in lithography lenses. The grating structure on a reticle comprising opaque lines, naked lines and π/2-phase-shifted grooves with their width ratio equal to 2/1/1 has a property such that either of the two first-order diffracted rays disappears entirely. The other first-order ray interferes with the zeroth-order ray to form tilted standing waves. Since a resist pattern of the grating is formed on top lines or valley lines of the standing waves, it moves with perfect linearity upon defocus. In this paper the quantitative metrology of even aberrations in a lithography lens is described along with a demonstration of an application of the grating reticle for a krypton fluoride excimer laser scanner with a numerical aperture (NA) of 0.73. Variation of the grating period along with a small-opening stopper inserted into the illuminator enlarge the measurable range of the pupil radius. The measurement technique described in this paper achieves high accuracy which is sufficient for small aberration lenses in state-of-the-art scanners.
Precipitation in As-Ion-Implanted and Annealed InAs
Authors: Seon-Ju Kim Seon-Ju Kim , Haewook Han Haewook Han
Published: October 2002

Low-energy As-ion-implanted InAs was examined using double-crystal X-ray diffraction and transmission electron microscopy. For uniform defect distribution, multiple implantations were made at 0.05–0.4 MeV with 4 ×1014–5×1015 ions/cm2. After annealing at 600°C for 20 min, As precipitates were observed, and the implantation-induced strain was significantly reduced, showing the recovery of crystallinity. The density of the As precipitates was 7.4 ×1016 cm-3 and the mean diameter was 55 Å, which corresponds to a volume fraction of 1.1%.
Evaporation of Silver during Chemical Vapor Deposition Process for YBa2Cu3O7 and its Effect on Microstructure
Authors: Ma Yanwei , Watanabe Kazuo , Awaji Satoshi , Motokawa Mitsuhiro
Published: October 2002

YBa2Cu3O7 (YBCO) films were simultaneously grown on both silver and MgO substrates by a chemical vapor deposition (CVD) technique. It is found that the transportation of silver occurs through the evaporation of silver from the silver substrate at the processing temperature of 850°C. The effect of the evaporation of silver during deposition was investigated. The silver vapor travels a distance of a few millimeters over the surface of a neighboring MgO substrate. It is also demonstrated for the first time that the presence of silver vapor causes some microstructural changes in the film grown on the MgO substrate.
Ferromagnetic Clusters on Disordered Si-Doped Ni3Mn Alloys
Authors: Ko Kowan Young , Al-Kanani Hassan J. , Booth J. Graham , Andersen Ken
Published: October 2002

The magnetic structures of disordered (Ni3-x
Si
x
)Mn alloys have been examined by polarized neutron scattering at a temperature range down to 2 K. Neutron powder diffraction showed the existence of atomic short-range order. Diffuse neutron scattering measurements revealed the presence of both ferromagnetic and antiferromagnetic correlation. The ferromagnetic correlation is enhanced as x is increased. Ferromagnetic clusters with a gyration radius of about 8 Å are present, the size of which varies little with temperature or composition.
Enhancement of the Faraday Rotation
Authors: Katsuragawa Tadao
Published: October 2002

The enhancement of the Faraday rotation is achieved by the following methods. 1) The Faraday rotation is enhanced approximately twofold by fabricating thin films containing fine iron particles, compared with continuous iron films. 2) After fabricating periodical groove structures on transparent substrates, thin films containing fine iron particles are deposited on the substrates using the evaporation method in gases. A large Faraday rotation about 60 times larger than that of continuous iron films with the same thickness is obtained. In the second case, a light intensity dependence is found.
Growth and Performance Study of Aluminum-Free InGaAs/GaAs/InGaAsP Strained Quantum-Well Pump Lasers
Authors: Shiao Hung-Pin , Lee Hsin-Ying , Lin Yow-Jon , Tu Yuan-Kuang , Lee Ching-Ting
Published: October 2002

The growth of InGaP, InGaAs and InGaAsP epilayers lattice matched to GaAs using the low pressure organometallic vapor phase epitaxy (LP-OMVPE) system was investigated. For the application of erbium-doped fiber amplifiers (EDFAs), the emission wavelength and far-field pattern of the pump laser were designed. The optical and electrical performances of the resultant pump laser were measured.
Temporal Stability of Second-Order Optical Nonlinearity of Polyurethane: Influence of Poling Conditions
Authors: Tsuchimori Masaaki , Watanabe Osamu , Okada Akane
Published: October 2002

Poling-condition dependence of second-order optical nonlinearity of a polyurethane sample has been studied by the second-harmonic generation (SHG) method. Not only the magnitude of an SHG coefficient (d
31) but also the temporal stability of d
31 depended on the poling conditions. The dependence of the temporal stability was weaker than that of the magnitude. The poling temperature (T
pol) affected the stability more than the poling voltage, the poling time and the preheating time. The T
pol leading to the best temporal stability agreed approximately with that leading to the highest d
31. The dependence of the temporal stability is discussed from the viewpoint of molecular dynamics.
Higher-Order Soliton Compression of Optical Pulses from 5 ps to 20 fs by a 15.1-m-long Single-Stage Step-like Dispersion Profiled Fiber
Authors: Igarashi Koji , Kishi Masato , Tsuchiya Masahiro
Published: October 2002

It has been successfully demonstrated to compress 5 ps optical pulses down to 20 fs by a 15.1-m-long single-stage step-like dispersion profiled fiber (SDPF) through a series of the higher-order soliton compression processes in conjunction with a single and ordinary erbium-doped fiber preamplifier. The SDPF compressor contains two kinds of dispersion-flattened fibers (DFFs) at its end and was composed by fiber-splicing with an aid of an extremely careful cutback method. In addition, we have compared the measured compression profiles in the 20–100 fs range with simulation results calculated on the bases of a few elementary soliton models and some experimentally extracted parameters, which is aimed to investigate and clarify its compression mechanism. It was found out that the standard nonlinear Schroedinger equation works appropriately to some extent even in the 30–100 fs range for the DFF used here, although some difficulty exists in modeling the pulse width evolution in the sub-30 fs range as far as the parameters that we used are concerned.
A Simulation Code for Tempo-Spatial Analysis of Three-Wave Interaction with Ultrashort- and Ultrahigh-Intensity Laser Pulses
Authors: Zhang Tiejun , Yonemura Motoki , Aoyama Makoto , Yamakawa Koichi
Published: October 2002

We have developed a simulation code that can be used for tempo-spatial analysis of three-wave interaction with ultrashort- and ultrahigh-intensity laser pulses. The code can be used to estimate conversion efficiency, tempo-spatial and spectral profiles and many transverse effects including diffraction, walk-off, phase modulations and self-focusing through the third-order nonlinear process. An application example of the code to second-harmonic generation is given in this short note.
Characteristics of Time Response of Self-Phase Modulation in Liquid Crystals
Authors: Hiroshi Ono Hiroshi Ono , Junichi Kikuhara Junichi Kikuhara
Published: October 2002

Transient characteristics of optical nonlinearity originating due to photothermal effects in liquid crystals has been characterized by use of heat-conduction analysis. The response time determined from the time-dependent heat-conduction analysis was in good agreement with that obtained from experimental observation. The transient properties including dependence of incident beam diameter and film thickness of liquid crystals are also explained by the theory described in this paper.
Droplet Epitaxy of InAs Nanocrystals on GaN/GaAs
Authors: Pietzonka Ines , Sass Torsten , Seifert Werner , Gray Struan , Mogensen Charlotte
Published: October 2002

The growth of InAs nanocrystals fabricated on GaAs by means of droplet epitaxy in a metal-organic chemical vapour-deposition chamber was investigated. To prevent deterioration of the droplet/substrate interface a nitride passivation layer was introduced. For this purpose both, nitridation of GaAs and GaN growth at different temperatures have been applied. In all nitrided samples and when GaN was grown at T
g=450°C, deep pit-like defects have been found in the GaAs below the InAs islands, caused by In that diffused from the droplets into the substrate along the {111} planes. Only the growth of a thin cubic GaN layer at T
g=550°C effectively prevented this indiffusion of indium into the substrate. The InAs islands contained stacking faults and twins that arose from defects in the underlying GaN layer. Their sidewalls do not only consist of (001) and {111} facets, but also of the commonly not observed {110} and even {111} facets. The frequent occurrence of holes at the center base of the InAs islands is discussed within a growth model for the transformation of In droplets to InAs nanocrystals.
Photocuring Kinetics for Polyfurfurylmethacrylate Doped with Fullerene: The Influence of Oxygen Partial Pressure on Sensitivity
Authors: Arai Hisayoshi , Tajima Yusuke , Takeuchi Kazuo
Published: October 2002

A new photosensitive resin, photo-oxidation induced polycondensation (POP) resin, was successfully prepared from poly(furfuryl methacrylate) (PFMA) and fullerene C60. The influence of oxygen supplied from ambient air into the POP resin on the photocuring was studied. The characteristic curves for the PFMA containing C60 film showed that the curing sensitivity was enhanced with increased partial pressure of oxygen. The relationship between sensitivity and oxygen partial pressure for low light intensity was explained reasonably well with a simple kinetic model. On the other hand, the sensitivity decreased for high light intensity. The numerical simulation indicated that the small oxygen solubility and small diffusivity were the cause of insufficient oxygen when the oxygen in PFMA was consumed promptly by high-intensity irradiation.