bluuebunny/crossref_metadata_2025 huggingface dataset:
Semi-Insulating Polysilicon Thin-Film Transistor: A Proposed Thin-Film Transistor
Authors: Choi Kwangsoo , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

We propose here two thin-film transistors (TFTs) using SIPOS (semi-insulating polysilicon) film. The first, named the homo TFT, has SIPOS film as its channel, and the second, named the hetero TFT, has poly-Si film as its channel and SIPOS film as its source and drain electrodes. Possible advantages of these TFTs have been discussed. The SIPOS film was fabricated using ArF excimer-laser crystallization of Si in oxygen ambient for application to the homo TFT.
It was found that both the on-current and the off-current can be controlled by crystallization conditions.
Threshold Estimation of GaN-Based Surface Emitting Lasers Operating in Ultraviolet Spectral Region
Authors: Honda Tohru , Katsube Atsushi , Sakaguchi Takahiro , Koyama Fumio , Kenichi Iga Kenichi Iga
Published: October 2002

The GaN-based vertical cavity surface emitting laser operating in the ultraviolet spectral region is proposed and its threshold current density is estimated. The calculated result indicates that low-threshold surface emitting lasers using a GaN layer as an active region can be realized by employing reasonably highly reflective mirrors such as AlN/AlGaN multilayer mirrors.
Analysis on the Tm3+, Ho3+ Concentrations in Alumino-Zirco-Fluoride Glass for Efficient 2-µ m Lasing
Authors: Doshida Minoru , Minoru Obara Minoru Obara
Published: October 2002

The dependence of gain coefficients for a Tm3+, Ho3+ co-doped alumino-zirco-fluoride glass on Ho3+ concentration under a 0.79 µ m pumping is described. The calculation of the gain coefficients is made with the upconversion rate constant from the lower coupled ( Tm3+3F4, Ho3+5I7) level to the upper coupled ( Tm3+3H5, Ho3+5I6) level. The gain is determined by measuring absorption coefficients and their appropriate comparison with a simple Tm3+-Ho3+ energy transfer model. The Tm3+, Ho3+ concentrations suitable for eyesafe laser applications at two micrometers are determined as a function of pumping intensity.
Distribution of Free Volume and Dielectric α-Relaxation in Glass-Forming Liquid Mixtures
Authors: Kakizaki Maeko , Anada Uichi , Hideshima Teruo
Published: October 2002

Anomalous change in the width of dielectric-loss band for liquid mixtures near and above their glass-transition temperatures is explained by a theory considering the distribution of free volume as in the case of a similar phenomenon observed in polymers. The data on the two solutions, bromobenzene in decalin and chlorobenzene in pyridine, given in the literature were analyzed as typical examples. The results show that this theory can explain the data on the liquid mixtures satisfactorily as in the case of those on polymers.
Spectroscopic Study of Rapid Mixing and Cooling of a High-Density He Plasma Flow Penetrating into Hydrogen Gas
Authors: Kamiura Yoshitomo , Takiyama Ken , Miyoshi Kozo , Mise Kimihiro , Oda Toshiatsu , Furukane Utaro
Published: October 2002

Rapid mixing and cooling of a high-density helium plasma flow injected into hydrogen gas was experimentally confirmed for the first time, which is essentially of importance to generate a recombining plasma as a short-wavelength laser medium. The plasma flow was produced by a small Z-pinch gun. The electron temperature and density was spectroscopically measured to be 12 eV and 6×1016cm-3, respectively, before injected into the hydrogen gas. After injection of the gas, the plasma was rapidly cooled down to 4 eV while the density increased only by about 30%. It was also found that the cooled plasma tended to a recombining phase. A simplified calculation was also performed on the collisional radiative model to show that the rapid cooling was due to the atomic collisions between the electrons and hydrogen atoms mixed with the plasma.
Dynamics of Nonlinear Structure with Magnetic Actuator
Authors: Tseng Chyuan-Yow , Pi-Cheng Tung Pi-Cheng Tung
Published: October 2002

The dynamics of a nonlinear structure with a nonlinear magnetic actuator are investigated. A single modal equation of motion is used to analyze the qualitative behaviors of the system. The effects of the feedback gains on the existence of the fractal basin boundaries and the region of the stability basins are considered. For the autonomous case, the resulting third-order system exhibits codimension two bifurcations in which pitchfork bifurcation, saddle connection bifurcation, and Hopf bifurcation exist. When the system is subjected to external disturbance, the Melnikov method was used to show the existence of chaotic motion and the fractal basin boundaries. Also, the global bifurcations in the parametric space are shown. The effects of feedback gains on the system is clearly illustrated by combining these two bifurcation structures. The numerical simulations are performed to verify our analytical results.
Conduction and Thermally Stimulated Currents in Langmuir-Blodgett Heterofilms with Arachidic Acid and C15TCNQ Layers
Authors: Kato Keizo , Ohashi Kenichi , Futao Kaneko Futao Kaneko
Published: October 2002

Electrical properties in Langmuir-Blodgett (LB) heterofilms with arachidic acid ( C20) and C15TCNQ layers were studied. Thermally stimulated currents (TSCs) were measured for C15TCNQ LB film and two types of structures of the LB heterofilms. Two peaks at around 270 K and 280 K were observed in their TSC spectra. The peak at about 270 K was found to be due to dipolar depolarization. The peak at about 280 K was considered to be due to injected carriers or mobile ions. TSCs in LB heterofilms depended on their structures and were different from TSC in C15TCNQ LB film. The difference in the TSCs seems to be caused by the energy structures generated in the LB heterofilms. Current vs voltage characteristics were also measured for the C15TCNQ LB film and the heterofilms. The conduction currents were found to be due to Schottky injections. The characteristics were also explained in terms of the effect of the electric fields at the electrode interfaces influenced by the potentials in the LB heterofilms.
Structural and Optical Properties of In-Plane Ordered Metallo-Phthalocyanine Thin Films Formed on Sapphire by Organic Molecular Beam Deposition
Authors: Hayashi Takayoshi , Maruno Tohru , Yamashita Akira , Fölsch Stefan , Kanbara Hirohisa , Konami Hideo , Hatano Masahiro
Published: October 2002

Thin films of dibenzo [b, t] phthalocyaninato-Zn(II) (ZnDBPc) were grown by UHV molecular beam deposition on polished sapphire (1̄012) surfaces. The structural and optical properties of the ZnDBPc films were investigated by atomic force microscopy, X-ray diffraction, polarization spectroscopy, and optical third harmonic generation. The films showed in-plane ordering over the entire substrate. Equally spaced atomic step arrays were clearly observed on the polished sapphire (1̄012) surface. The ZnDBPc molecules stacked themselves to form molecular columns, and the stacking direction was parallel to the step direction, resulting in in-plane ordering of the ZnDBPc films. The ordered ZnDBPc film strongly promoted the ordering of a TiOPc thin film deposited on it. The third-order nonlinear optical susceptibility χ(3) of this ordered TiOPc/ZnDBPc double-layer film showed high anisotropy, and its maximum χ(3) value was 3.0×10-10 esu.
Direct Measurement of Molecular Flux in Organic Molecular Beam Deposition
Authors: Yase Kiyoshi , Yuji Yoshida Yuji Yoshida
Published: October 2002

Mass distribution and molecular flux during sublimation of several functional organic compounds such as tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ), Copper-phthalocyanine and fullerene in ultrahigh vacuum are directly measured using a high-performance quadrupole mass spectrometer. It was confirmed that molecules in a complexed form sublime as individual molecules from a Knudsen cell (K-cell). The dependence of evaporation rate on the temperature of the K-cell was numerically calibrated for the first time.
Oxygen-Plasma-Treated Superconductor-Insulator-Superconductor Junction for Radiation Detector
Authors: Suga Mitsuo , Shinya Kominami Shinya Kominami
Published: October 2002

To reduce leakage current of S-I-S junctions for radiation detection, usefulness of an oxygen plasma treatment for edges of the junctions has been studied. Temperature dependences of subgap currents of the junctions are measured. From these dependences, maximum leakage currents flowing through the edges of the junctions are estimated. These leakage currents are comparable to the smallest leakage current reported for anodized S-I-S junctions.
New KrF and ArF Excimer Lasers for Advanced Deep Ultraviolet Optical Lithography
Authors: Endert Heinrich , Pätzel Rainer , Rebhan Ulrich , Powell Michael , Dirk Basting Dirk Basting
Published: October 2002

Advanced deep ultraviolet (DUV) optical lithography requires reliable high repetition rate excimer lasers at low cost of ownership. We optimized all components of the laser cavity. The result is a new metal/high-density ceramic laser tube with long life discharge components. It meets the specifications of the next generation of DUV laser sources. The new laser cavity was tested in several test runs at 193 nm (ArF) and 248 nm (KrF) and demonstrated excellent gas lifetime data when compared to conventionally designed lasers. For the first time a KrF laser was successfully operated in a quasi sealed-off mode for more than 1 billion pulses. The lifetime data of narrow bandwidth lasers necessary for DUV optical lithography tools also increase significantly. A 500 Hz 6 W laser with a bandwidth of 0.9 µ m passed in a marathon test 1.1 billion pulses and the gas lifetime exceeded 200 million pulses routinely. Additionally, we operated this laser at 8 W average power and 600 Hz.
Infrared- and Visible-Light-Sensitive Spatial Light Modulator Using Pigment-Dispersed Organic Photoconductor
Authors: Fujikake Hideo , Takizawa Kuniharu , Kikuchi Hiroshi , Hirose Juichi , Kobayashi Tatsushi , Matsumoto Tatsuru
Published: October 2002

A new spatial light modulator using an organic photoconductor and a polymer-dispersed liquid crystal film is developed which has sensitivity to both infrared and visible light. The photoconductor contains organic pigment of titanylphthalocyanine microcrystal particles in binder polymer and generates photocarriers under light irradiation. The device is applicable to infrared image viewers and optically addressed projection displays using various write light sources including a compact infrared laser diode. Its display application is especially significant because the liquid crystal film has the attractive feature of high transmittance for bright-image projection. The device exhibited a good contrast ratio of 40:1 and high limiting resolution of 40 lp/mm. Optical conversion from a faint near- infrared image of a candle flame to a visible image was demonstrated in real time.
Fatigue Behavior in Lead-Zirconate-Titanate Thin-Film Capacitors Prepared by Pulsed Laser Ablation on Ni-Alloy Electrodes
Authors: Morimoto Akiharu , Yamanaka Yasuhiro , Tatsuo Shimizu Tatsuo Shimizu
Published: October 2002

Ferroelectric lead-zirconate-titanate (Pb(Zr0.52Ti0.48)O3: PZT) thin-film capacitors were fabricated by pulsed laser ablation using Ni-alloy electrodes on oxidized (100) silicon. Polarization fatigue after a large number of switchings was investigated with a variety of frequencies. The frequencies for acceleration of fatigue and for measurement of the switched charge density Q
sw were varied simultaneously or independently. The fatigue test revealed that the increase in the frequency both for acceleration and measurement of switching pulse increases the life of polarization reversal while it decreases Q
sw. At 50 kHz, Q
sw keeps the initial value even after switching above 1010 cycles. The measurement frequency dependence of Q
sw suggests that a homogeneous fatigue takes place irrespective of fast and slow domains and additional layers of a low dielectric constant are probably formed in the ferroelectric-metal interface.
High Temperature X-Ray Diffraction Study of Melt Structure of Silicon
Authors: Waseda Yoshio , Shinoda Kozo , Sugiyama Kazumasa , Takeda Susumu , Terashima Kazutaka , Toguri James Makoto
Published: October 2002

The structure of molten silicon has been determined at three temperatures of 1440, 1460 and 1520° C by X-ray diffraction. All structure factors indicate a characteristic small hump on the higher wave vector side of the first peak and such specific feature becomes slightly obscure as the temperature increases. A small peak is found in the region between the first (0.245 nm) and second (0.55 nm) main peaks in the pair distribution functions with a shallow minimum at about 0.35 nm. This is not observed in the pair distribution functions for usual molten metals. The coordination numbers in the near-neighbor region have been estimated by applying the interference function refining technique and the results for the first two neighbors are 6.3 (4.6+1.7) at 1440° C, 5.7 (4.5+1.2) at 1460° C and 5.8 (4.4+1.4) at 1520° C. The present structural information is consistent with the recent results of density and electrical resistivity of molten silicon.
A Radial Molecular Orientation Using a Flow-Induced Aligning Method in a Nematic Liquid Crystal Cell
Authors: Shin Masuda Shin Masuda , Toshiaki Nose Toshiaki Nose , Rumiko Yamaguchi Rumiko Yamaguchi , Susumu Sato Susumu Sato
Published: October 2002

The radially symmetrical molecular orientation is demonstrated by using a flow-induced aligning method in a nematic liquid crystal (LC) on a PVA-coated substrate without a rubbing treatment. The radial molecular orientation of good quality is obtained as compared with the LC cell using a radial rubbing treatment. The diameter of the area with the radial orientation is above five times larger than that obtained by a memory effect of molecular orientation in an electric field produced by a hole-patterned electrode structure. A radially and homogeneously aligned LC cell is prepared, and a molecular orientation state and polarization converting properties are clarified by observations of transmission images and measurements of transmission properties. The effect of a chiral dopant in the LC cell is also investigated, and it is found that the chiral pitch of LC materials can be determined by a rotation angle of disclination line.
Competition between Electrostatic and Capillary Forces Acting on a Single Particle
Authors: Yamamoto Kazushige , Tanuma Chiaki , Gemma Nobuhiro
Published: October 2002

Using an AFM, interactions between a conducting particle and SiO2/Si substrates with different hydrophilicities have been investigated with voltage applied in air. Attractive forces observed on hydrophobic substrates showed simple V
2 dependence at any distance, and was purely of electrostatic interaction. Forces measured for hydrophilic substrates, on the other hand, exhibited the complicated dependence on V and distance. V dependence of the force for hydrophilic substrates showed that the interaction changed continuously from electrostatic at long distances to capillary condensation at short distances including the contact region. This interaction change could be explained by electrification and deformation of the water layer adsorbing onto hydrophilic surfaces, the sudden formation of the water bridge, and the enlargement of the cross section area of the water bridge.
Measurements of Plasma Flow Velocity in DC Plasma Jets Using Perpendicular and Parallel Mach Probes
Authors: Chung Kyu-Sun , Hong Sang-Hee , Chung Kie-Hyung
Published: October 2002

A rotating electric probe system has been developed to measure the parameters of spray plasma jets from a dc plasma torch at atmospheric pressure. Four different types of unmagnetized single probes have been used for the diagnostics of high power-flux plasma–two probes are mutually perpendicular (`perpendicular mach probe') and the remaining two are oppositely directed to each other (`parallel mach probe')–to measure the plasma flow velocity and density along the axial and radial directions of the plasma flame. Near the nozzle exit of a 15 kW plasma torch, plasma flow velocity, density and electron temperature are measured as ∼910 m/s, 4×1013 cm-3 and 4.7 eV, respectively.
Dry-Etching Durability of Copolymers and Polymer Blends of Vinylnaphthalene or α-Methylstyrene with Methyl Methacrylate
Authors: Kushida Masahito , Imaizumi Yoshiaki , Harada Kieko , Ueno Nobuo , Kazuyuki Sugita Kazuyuki Sugita
Published: October 2002

Dry-etching durabilities of poly(2-vinylnaphthalene-co-methyl methacrylate), the blend of poly(2-vinylnaphthalene) and poly(methyl methacrylate) [PMMA], and poly(α-methylstyrene-co-methyl methacrylate) films were studied as a function of vinylnaphthalene or α-methylstyrene content against four types of dry etching: 1) O2 plasma etching ( O2 PE), 2) O2 reactive ion etching ( O2 RIE), 3) Ar+ sputter etching (Ar SE), and 4) Ar ion beam etching (Ar IBE). Since the etching depth increased linearly with etching time the two-component polymer films were regarded to be etched uniformly without selected removal of aliphatic monomer units. Substantial enhacement of the durability was observed by incorporating or blending small amounts of aromatic moiety into PMMA for physical etching (Ar SE, Ar IBE) and physical/chemical etching ( O2 RIE) as well as chemical etching ( O2 PE). O2 RIE is a synergetic process involving both physical bombardment and chemical reaction.
Submicron Optical Lithography Based on a New Interferometric Phase Shifting Technique
Authors: Motoi Kido Motoi Kido , Gabor Szabó Gabor Szabó , Joseph R. Cavallaro Joseph R. Cavallaro , William L. Wilson William L. Wilson , Michael C. Smayling Michael C. Smayling , Frank K. Tittel Frank K. Tittel
Published: October 2002

This paper reports the computer simulation and experimental demonstration of a new phase shifting technique based on interferometry that is especially suited for deep ultraviolet (UV) microlithography. Significant resolution and contrast enhancement can be achieved using a chrome binary mask. Image analysis based on charge coupled device (CCD) detection and patterns recorded in UV photoresist has been used to study the capabilities of this new approach. Lines with a feature size as fine as 0.3 µm have been demonstrated using 355 nm illumination.
Tomonaga-Luttinger Liquid Effects on Transport in Quantum Wires
Authors: Arisato Kawabata Arisato Kawabata
Published: October 2002

Effects of the electron-electron interaction on the transport in quasi one-dimensional systems are studied theoretically. The theory is applied to multi-subband quantum wires, and the temperature dependence of the resistance is predicted.
Current Response of Quantum Dot Modulated by Time-Dependent External Fields
Authors: Susumu Adachi Susumu Adachi , Kazuya Fujimoto Kazuya Fujimoto , Tsuyoshi Hatano Tsuyoshi Hatano , Yoshimasa Isawa Yoshimasa Isawa
Published: October 2002

We study how the dc transport through a semiconductor quantum dot varies when time-dependent external fields are applied. We find (i) the shift of the Coulomb blockade region due to the interband excitation, (ii) the resonant peak structures of the Coulomb oscillation due to the intraband excitation, and (iii) the electron pumping effect in the quantum dot modulated by the microwave field with frequency lower than the level spacing of the quantum dot.
Local Current Distribution in the Presence of Nonequilibrium Distribution of Edge States
Authors: Hiroshi Hirai Hiroshi Hirai , Susumu Komiyama Susumu Komiyama
Published: October 2002

Local current distribution in the presence of nonequilibrium distribution between different edge states in a quantum Hall effect regime is theoretically studied by explicitly taking into account extra charge added into edge states. The extra charges produce a Hall electric field that induces Hall currentIH. Total current is the sum ofIHand the chemical-potential edge currentICEcarried by the extra charges themselves. The calculation shows thatICE≪IH. When the local current distribution is represented by a “response current densityjR," it generally spreads out into the interior region of a conductor, while its amplitude increases as the sample boundaries are approached. When the local current distribution is represented by a “Fermi-surface current densityjF," it is strictly localized at the edge states.
Is There a Magnetic-Field-Induced Breakdown in the Universality of Conductance Fluctuations?
Authors: David K. Ferry David K. Ferry , Gerard Edwards Gerard Edwards , Kazunuki Yamamoto Kazunuki Yamamoto , Yuichi Ochiai Yuichi Ochiai , Jonathon Bird Jonathon Bird , Koji Ishibashi Koji Ishibashi , Yoshinobu Aoyagi Yoshinobu Aoyagi , Takuo Sugano Takuo Sugano
Published: October 2002

Over the past few years, there have been many reports of the breakdown of universality in conductance fluctuations in mesoscopic systems when a high magnetic field is applied, particularly in the case of quantum wires. Normally, conductance fluctuations are described by a single scaling parameter–the coherence lengthlφ. The increase in the magnetic coherence lengthBcis generally attributed to a decrease inlφwhich is not observed in the amplitude of the fluctuations. Worse, in high mobility material, the fluctuations seem to increase in amplitude, which is also inconsistent with a decrease inlφ. Here, we argue that (1) the wire behavior is governed by surface scattering, (2) there is a formation of edge states in the high magnetic field, and (3) a breakdown of diffusive transport and transition to quasi-ballistic transport in the edge states in high-mobility material. The transition to high field behavior occurs when the cyclotron orbit at the Fermi surface becomes smaller than the width, so that proper treatment of the amplitude of the fluctuations and of the magnetic correlation length remains in keeping with theoretically expected behavior without loss of universality.
Quantum Interference Phenomena in an Electron-Wave Directional Coupler with Finite Coupling Length
Authors: Ryosaku Kaji Ryosaku Kaji , Masanori Koshiba Masanori Koshiba
Published: October 2002

A new type of quantum field effect directional coupler with finite coupling length is studied with the equivalent network approach. The coupler analyzed is composed of GaAs/Ga1-x
AlxAs and has finite external potential barriers and longitudinal discontinuities. Although this structure is analogous to that in an optical counterpart, there is no radiation loss. Numerical results show that the effects of the longitudinal interference appear as a short-periodic behavior of the transmission probability and the effects of the beat of two normal modes appear as a long-periodic behavior of the transmission probability.
Theory of Spontaneous Emission Observed Outside a Microcavity
Authors: Ichiro Takahashi Ichiro Takahashi , Kikuo Ujihara Kikuo Ujihara
Published: October 2002

A formula describing the intensity of spontaneous emission outside a planar microcavity is derived quantum mechanically. It reflects the quantum mechanical interference of the atom and the emitted photon via multiple reflections in the cavity. The expression derived for the power spectrum reproduces the results of the classical theory by Huang et al.. [Appl. Phys. Lett. 61 (1992) 2961]. The quantum mechanical expression for the electric field amplitude for a single emission event is given together with its evolution equation.
Enhancement and Suppression Effect of Carbon Atoms on Oxygen Aggregation and New Donor Formation in Silicon Crystals Preannealed at Low Temperatures
Authors: Yamanaka Hideki , Miyamoto Nobuo
Published: October 2002

We have investigated the effect of preannealing in the 400-800° C range and carbon atoms on formation of oxygen aggregates and new donors upon prolonged annealing at 650° C. Suppression of both oxygen aggregation and new donor formation occurs even in high-carbon-content silicon, which was preannealed at 700° C for a long period. Enhancement occurs in silicon preannealed at 500° C irrespective of carbon concentration. The suppression and the enhancement are caused by absence and presence of agglomeration of silicon self-interstitials (Si)
i
s, respectively. Absence of agglomeration of (Si)
i
s is due to less excess of (Si)
i
s emitted from a small number of large oxygen aggregates formed at 700° C. Accordingly, the emission of (Si)
i
s and oxygen aggregation are so suppressed as not to increase the energy due to the (Si)
i
formation. Hence, the large oxygen aggregates are transformed to platelike oxygen precipitates during prolonged annealing at 650° C to decrease the strain energy. Agglomeration of (Si)
i
s is due to greater excess of (Si)
i
s emitted from a number of small oxygen aggregates formed at 500° C. Further emission of (Si)
i
s can proceed during annealing at 650° C; thus, oxygen aggregation is enhanced, and agglomerates of (Si)
i
s develop into rodlike defects and dislocation dipoles.
Damage in a GaAs Surface Caused by RF-Sputter Deposition of SiO2
Authors: Mitani Katsushiko , Toshihiro Kawano Toshihiro Kawano
Published: October 2002

Structural and optical changes in a GaAs surface due to rf sputter deposition of SiO2 were investigated by means of transmission electron microscopy (TEM) and spectroscopic ellipsometry (SE). A blight-field image indicates the occurrence of a surface-modified layer of about 7-9 nm thickness in the GaAs surface after SiO2 deposition, at an rf power density of 1.7 W/cm2. A lattice image shows the increased interfacial roughness between GaAs and SiO2 upon the deposition. The thickness of the optically-modified layer in SiO2-deposited GaAs is estimated by SE, using the amorphous semiconductor dispersion model. At the lower rf power deposition, the extents of damage estimated by TEM and SE were found to be enhanced. Both rf-power and SiO2-deposition-rate dependences of damage suggest that impingement by non-depositing particles in the initial stage causes surface modification.
Photoconductivity and Thermoelectric Power of ZnxCd1-xSe Films
Authors: Gupta Phalguni , Maiti Biswajit , Chaudhuri Subhadra , Arun K. Pal Arun K. Pal
Published: October 2002

ZnxCd1-xSe (0≤x≤1) films were deposited by two zone hot wall evaporation technique. X-ray diffraction analysis of the films indicated a predominant wurtzite structure forx<0.5, which changed to zinc blende structure forx>0.7. The films had a mixed structure for 0.5<x<0.7. The films were highly resistive (resistivity varying within 3 Ω· cm to 1.5×105Ω· cm for 0≤x≤1.0) with partially depleted grains. The optical band gap (Eg), determined from the reflectance measurements, indicated a direct transition with a bowing effect inEgversusxplot. The conductivity at low temperature (forx<0.6) could be explained by thermionic emission over the intercrystalline barrier, while for higherxquantum mechanical tunneling through the barrier became predominant. The variation of the barrier height (Ebd) with the intensity of illumination was obtained from the photoconductivity measurements. The majority carrier capture cross-section ( 1-4×10-18cm2) of the grain boundary traps ( 1×1011-1×1012cm-2) was determined. The effect of the intercrystalline barrier on the thermoelectric power measurements was also considered.
Interfacial Reactions in Al-Alloy/Ti/Silicon-Dioxide-Based Substrate Structures for Multilayered Interconnects
Authors: Onoda Hiroshi , Narita Tadashi , Keiichi Hashimoto Keiichi Hashimoto
Published: October 2002

Interfacial reactions in Al-alloy/Ti/borophosphosilicate glass (BPSG)/Si-substrate structures have been investigated up to the annealing temperature of 550° C. The interfacial reaction changes according to the annealing temperature. Below 500° C, a reaction between Al alloy and Ti occurs, and the main reaction product is Al3Ti. The underlying BPSG film remains almost inert. At 550° C, the substrate BPSG film is no longer inert and a reaction between Al alloy, Ti and underlying BPSG film takes place. The reaction never occurs without the Ti layer. Reactions in the Al-Ti-Si-O four-component system must be considered in this temperature range. The main reaction product is Ti7Al5Si12. After the Ti layer is consumed for Al3Ti formation, Al3Ti and BPSG react to form Ti7Al5Si12, and a lot of Al moves into BPSG film through the Ti7Al5Si12. Reaction retardation by alloying Al with Si also occurs in this temperature range.
Investigation of a High Quality and Ultraviolet-Light Transparent Plasma-Enhanced Chemical Vapor Deposition Silicon Nitride Film for Non-Volatile Memory Application
Authors: Wang Chin-Kun , Ying Tser-Liang , Wei Chih-Shih , Liu Lu-Min , Cheng Huang-Chung , Lin Mou-Shiung
Published: October 2002

A high quality and ultraviolet-light transparent (UV-transparent) plasma enhanced chemical vapor deposition (PECVD) silicon nitride ( SiNx) film is developed to form passivation layer for non-volatile memory devices. Comparing to the conventional PECVD SiNxfilm known to have tensile stress and opacity to ultraviolet-light (UV-light), the proposed SiNxfilm with very low compressive stress ( <1×109dyn/cm2) and excellent UV-transmittance (>70% for 1.6 µ m-thick film) can be achieved. The film stress is strongly related to RF input power during deposition process. The UV-transmittance is influenced by pressure and SiH4/NH3flow ratio. It is also shown that the UV-transmittance is closely correlated to refractive index (RI), film density as well as N/Si ratio inside the film. This SiNxfilm has been successfully applied to erasable programming read-only memory (EPROM's) devices, and very good UV-erasability and reliability performances are demonstrated.
Constant Voltage Trimming of Heavily Doped Polysilicon Resistors
Authors: Kato Kotaro , Terukazu Ono Terukazu Ono
Published: October 2002

Constant voltage trimming (CVT) characteristics of heavily doped polysilicon resistors are analyzed using the melting-segregation model which has already been proposed to explain the mechanism of constant current trimming (CCT). The stability of CVT is found to be ensured by the exsistence of grain resistance in polysilicon which plays no role in CCT. The theoretical expression for CVT characteristics derived from the melting-segregation model, modified by the temperature dependence of grain resistance, agrees well with experimental data.
Effects of Substrate Temperature and Oxygen Partial Pressure on the Properties of Sputtered Zirconium Titanate Thin Films
Authors: Chang De-An , Lin Pang , Tseung-Yuen Tseng Tseung-Yuen Tseng
Published: October 2002

We report the effects of substrate temperature and O2/Ar ratios on the properties of ZrTiO4thin films prepared by RF magnetron sputtering. The films were deposited at a constant gas pressure (0.133 Pa) with various substrate temperatures (25-450° C) and different O2/Ar ratios from 0/100 to 20/80. The deposition rate decreases with increasing oxygen partial pressure and substrate temperature. Moreover, the higher O2content increases the surface roughness of deposited films, which reduces the transmittance of the films. The effects of substrate temperature and oxygen partial pressure on the stoichiometric composition, optical constant, crystallinity phase, surface morphology, and adhesion have also been systematically investigated.
Effects of (100)-Textured LaNiO3 Electrode on Crystallization and Properties of Sol-Gel-Derived Pb(Zr0.53Ti0.47)O3 Thin Films
Authors: Chen Ming-Sen , Wu Jenn-Ming , Tai-Bor Wu Tai-Bor Wu
Published: October 2002

Sol-gel-derived thin films of Pb(Zr0.53Ti0.47)O3 (PZT) were spin-coated onto the (100)-textured LaNiO3 (LNO) electrode which was deposited on a Pt/Ti/SiO2/Si substrate by rf magnetron sputtering at 350° C. The annealing temperature for obtaining a perovskite PZT film on LNO was reduced by about 50° C compared with that direct deposition on Pt. Highly a- and c-axis-oriented PZT films were obtained by annealing at temperatures above 500° C, while randomly oriented films were formed on Pt electrode. Moreover, the grain size of PZT films grown on LNO was smaller than that of films on Pt. The dielectric constant, ε
r, remanent polarization, P
r, and coercive field, E
c, of PZT films on LNO changed markedly with the annealing conditions. ε
r increased and both P
r and E
c markedly decreased with increasing annealing temperature or time, which was attributed to the out-diffusion of LaNiO3 into PZT films during annealing. Use of the LNO layer as a bottom electrode was also found to greatly improve the fatigue property of PZT films.
Development of Biaxially Stretched Film for Flexible Printed Circuit Boards
Authors: Shirouzu Shigenori , Ishii Tatsuo , Iga Toru , Chino Shinji , Hayasi Mikiya , Tomioka Tatuya , Sibasaki Sachiko , Arai Yosuke , Ooki Yuichi , Kaoru Hayashi Kaoru Hayashi
Published: October 2002

A biaxially stretched film of BEK, a new engineering plastic with high heat resistance (T
g: 181° C, T
m: 364° C) and chemical resistance, was developed as a base film for flexible printed circuit boards. Its heat shrinkage percentage at 260° C and the coefficient of thermal expansion below T
g were decreased to below 0.1%, and 3.3×10-5/° C, respectively. The process of determining stretching and heat setting conditions for film formation with a role stretcher and a tenter is reported.
Modified Crystal Rotation Method for Measuring High Pretilt Angle in Liquid Crystal Cells
Authors: Shirota Koichiro , Yaginuma Michio , Ishikawa Ken , Takezoe Hideo , Atsuo Fukuda Atsuo Fukuda
Published: October 2002

We propose a modified crystal rotation method which enables us to measure high pretilt angles in liquid crystal cells. This method is based on the use of two prisms made of the same material as the liquid crystal cell substrates. We demonstrate the ability for measuring a pretilt angle of over 21°.
Thin Ag Film Formation by Deposition of Accelerated Ag Ions
Authors: Iida Shoji , Nakamura Tomomi , Ashimura Yoshimichi , Shindo Tomohiro
Published: October 2002

Ag vapor was ionized and accelerated by an electric field to form a thin film on Si(100) and Si(111) substrates. Despite a small ionization ratio, this deposition system produced a flatter and more highly crystallized film than the conventional deposition system. As a result, the Schottky barrier height decreased with the increase in crystallization. This suggests that the barrier height may be changed in accordance with the degree of metal film crystallization and the surface density of the silicon substrate.
Scattering Process of Low-Energy Ions from Binary Compound Surfaces at 180°
Authors: Kawamoto Kiyoshi , Kenjiro Oura Kenjiro Oura
Published: October 2002

Scattering processes of low-energy ions ( ∼10 keV) from binary compound surfaces have been studied by computer simulation. For scattering angles close to 180°, since the incident and outgoing trajectories are considered to be almost the same, any target atoms which participate in a shadowing interaction will also be involved in blocking. It has been found that the blocking effect is dominant at the critical angle at monatomic crystal surfaces, compared with the shadowing effect. In the present paper, we clearly show that the blocking effect on the outgoing trajectory becomes more important, provided that the target atom is lighter than the focusing atom. Due to the blocking effect, both the intensity and the critical angle for scattering are strongly dependent on the scattering angle near 180°.
Visualization of Blood Flow with Two-Dimensional Moving Target Indication
Authors: Tsuyoshi Kimura Tsuyoshi Kimura , Ayumu Matani Ayumu Matani , Osamu Oshiro Osamu Oshiro , Kunihiro Chihara Kunihiro Chihara
Published: October 2002

Based on high-frame-rate digital subtraction echography (HFDSE), we developed a new imaging method to visualize blood flow, i.e., two-dimensional moving target indication (2D-MTI). This method reveals blood flow on a plane by extracting a moving target in the blood flow from ultrasonic B-mode images and tracking it on successive images. Experiments were performed using a model flow path. The results show that particles were extracted from ultrasonic B-mode images, and flow was visualized.
Evaluation of Large-Area Mo/Si Multilayer Soft X-Ray Mirrors Fabricated by RF Magnetron Sputtering
Authors: Takenaka Hisataka , Kawamura Tomoaki , Haga Tsuneyuki , Kinoshita Hiroo , Yoshikazu Ishii Yoshikazu Ishii
Published: October 2002

It was determined by calculation that the soft X-ray reflectivities of Tc/Si, Mo/Si, Nb/Si, and Ru/Si multilayers are highest at 13 nm wavelength. Six-inch-diameter Mo/Si multilayers, selected from among these multilayers, were fabricated by an rf magnetron sputtering system. Their periodic length uniformity was good (better than +/-1% deviation over the entire surface area) and the layer interfaces were fairly well defined. Reflectivity of 63% at around 13.7 nm wavelength was achieved at 3-degrees from normal incidence. Large-area high-quality multilayer mirrors for soft X-ray projection lithography can thus be fabricated using this rf magnetron sputtering system.
Atomic Layer Etching of Silicon by Thermal Desorption Method
Authors: Shigeru Imai Shigeru Imai , Takeo Haga Takeo Haga , Osamu Matsuzaki Osamu Matsuzaki , Takeo Hattori Takeo Hattori , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Atomic layer etching of Si has been realized by modulating the substrate temperature synchronized with chlorine gas irradiation. This is based on the surface chemistry wherein chlorine atoms adsorbed on the clean Si surface at room temperature are thermally desorbed as SiCl2 over 650°C. For Si(111) substrates, the etching rate R was saturated at about 3/7 monolayer per cycle for the peak temperature of more than 675°C. The saturated etching rate corresponds to half the number of rest atoms of the Si(111) 7 ×7 surface. The chlorine dosage for the saturation was about 3.5 mTorr × 4 s. The experimental results agreed well with the theoretical estimations based on the desorption kinetics of SiCl2. The increase of the surface roughness by etching was less than one monolayer.
Characterization of Strained GaP/Si Heterostructure by Spectroscopic Ellipsometry
Authors: Guolin Yu Guolin Yu , Tetsuo Soga Tetsuo Soga , Takashi Jimbo Takashi Jimbo , Masayoshi Umeno Masayoshi Umeno
Published: October 2002

Spectroscopic ellipsometry has been used to study the strained epitaxial layers of GaP on a Si substrate with varying thicknesses. The variation of band-gap energy from the bulk value (ΔE
1) for the GaP layer and Si substrate is determined by a new method of analysis, together with the thicknesses of the surface natural oxide layer and the epitaxial GaP layer. The results are compared with the data from the literature.
Considerations on Growth Parameters for Dynamic Congruent-State Growth of LiNbO3
Authors: Uda Satoshi , Shimamura Kiyoshi , Fukuda Tsuguo
Published: October 2002

Each ionic species of LiNbO3 melt has a particular field-modified equilibrium partition coefficient, k
E0, and effective partition coefficient, k
E, which are predominated by growth parameters, i.e., solute boundary layer thickness, δ C, growth velocity, V and temperature gradient, G
L. Variations of these coefficients have been discussed in association with growth parameters and a combination of δ C(g), V(g) and G
L(g) as a function of solidified melt fraction, g, was calculated for true dynamic congruent-state growth from a finite amount of melt when the interface electric field is taken into account.
Switching Characteristics in Antiferroelectric Liquid Crystals under Application of Bipolar Pulse Voltage
Authors: Hayashi Hitoshi , Takemura Makoto , Kikuchi Katsuhide , Takigawa Kenji , Inata Masashi , Hijikata Yoshimasa , Ezaka Kazuaki , Shindo Hitoshi , Orihara Hiroshi , Ishibashi Yoshihiro
Published: October 2002

The electrooptical responses of antiferroelectric liquid crystals (AFLCs) under bipolar pulse voltages for the ariving scheme actually used in practice have been investigated. The samples used were 4-(1-trifluoromethylheptyloxycarbonyl)phenyl-4′-octyloxybiphenyl-4-carboxylate (TFMHPOBC) and its homologues. It was found that the V (applied voltage)- T (transmittance) characteristics were affected by the chemical structures such as the type of chiral radical and the length of the alkyl chain. The V-T curves at low temperatures showed an anomalous behavior, i.e., in addition to the usual increase of the transmittance in the low voltage region the transmittance has a maximum and a minimum in the high voltage region.
Dielectric Properties of Pb(ZrxTi 1-x)O 3 Single Crystals Including Monoclinic Zirconia
Authors: Tatsuya Hatanaka Tatsuya Hatanaka , Hideo Hasegawa Hideo Hasegawa
Published: October 2002

Pb(ZrxTi1-x
)O3 single crystals including monoclinic zirconia were grown from Pb(Zr0.5Ti0.5)O3 ceramics in a PbO-KF-PbCl2 flux. The composition of the crystals was determined as Pb(Zr0.3Ti0.7)O3 and the crystals included 8 vol% zirconia particles with a size of ∼5 µm. The dielectric constants showed a maximun around 415°C although the expected phase transition point (T
c) is about 440°C. The shift of T
c was discussed in terms of the phenomenological Landau theory and explained by the existence of the internal compressive stress caused by the volume expansion of ZrO2.
Observation of Domain Structure in Triglycine Sulfate by a Pyroelectric Probe Technique
Authors: Nakatani Noriyuki , Hayakawa Kouichi , Hiroyasu Inoue Hiroyasu Inoue
Published: October 2002

Ferroelectric domain structure in triglycine sulfate (TGS) was observed by a system based on a pyroelectric probe technique. A light beam from a laser diode was focused on the surface of a TGS specimen, and the specimen was two-dimensionally scanned by an X-Y pulse stage. Analyzing the pyroelectric signal, we obtained high-resolution domain patterns. The whole system was controlled with a computer. The scanning area was from 0.5×0.5 mm2 to 10×10 mm2. Imaging of an area took about 30 min. Changes of domain structure caused by successive application of pulsed electric field were also examined. Some interesting results concerning the domain dynamics in TGS were obtained.
Effect of B-Ions Substitution in [(K1/2Bi1/2)-(Na1/2Bi1/2)](Ti-B)O3 System with B=Zr, Fe1/2Nb1/2, Zn1/3Nb2/3 or Mg1/3Nb2/3
Authors: Yamada Yasuyuki , Akutsu Tatsuya , Asada Hiroshi , Nozawa Koji , Hachiga Shinji , Kurosaki Takeshi , Ikagawa Osamu , Fujiki Hiroyuki , Hozumi Katsuhiro , Kawamura Takeshi , Amakawa Takashi , Hirota Ken-ichi , Takuro Ikeda Takuro Ikeda
Published: October 2002

Phase relationship in the [(K1/2Bi1/2)1-
y

(Na1/2Bi1/2)

y

](Ti1-
x

B

x

)O3 system with B=Zr, Fe1/2Nb1/2, Zn1/3Nb2/3 or Mg1/3Nb2/3 has been investigated by dielectric measurement and X-ray diffractometry. All of the bi-binary systems were solid-soluble throughout the entire composition range. With increasing y and x, ferroelectric Curie point decreased and the ε-T curve became flat. Composition dependence of the transition temperature was examined by varying x or y. Phase diagrams were mostly determined at room temperature on square diagrams except for a restricted area in the vicinity of (Na1/2B1/2)ZrO3, which involved a tetragonally distorted phase and could not be accounted for. The ferroelectric tetragonal phase was confined within a narrow range of x<0.1 and the rhombohedral phase was dominant in all of the systems studied here.
Enhancement of Field-Excited Electron Emission from Lead-Zirconate-Titanate Ceramic Using Ultrathin Metal Electrode
Authors: Kuratani Yasuhiro , Omura Seiji , Okuyama Masanori , Yoshihiro Hamakawa Yoshihiro Hamakawa
Published: October 2002

Electron emission from ferroelectric ceramic having ultrathin metal electrode has been observed in vacuum by applying a pair of bipolar pulse voltages. Ultrathin metal film was deposited on lead-zirconate-titanate (PZT) ceramic plate to enhance electron emission. The amount of emitted charge in the sample using the ultrathin metal film could increase to about 4 times that in the sample using a conventional electrode. Further electron emission could be observed even by impressing an unipolar pulse of negative voltage.
Raman Spectroscopy and Positron Lifetime Studies of Structural Relaxation and Defect Evolution in Amorphous Silicon
Authors: Hiroyama Yuichi , Suzuki Ryoichi , Hirano Yoshiyuki , Sato Fumio , Teruaki Motooka Teruaki Motooka
Published: October 2002

Correlations between structural relaxation and defect evolution in amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) have been investigated by Raman scattering spectroscopy and positron lifetime measurements. Various a-Si films were prepared by ion implantation, evaporation, and electron-cyclotron resonance plasma-enhanced chemical vapor deposition (ECR CVD). The bond angle deviation, Δθ, of nonhydrogenated a-Si decreased during 450° C isothermal annealing, while Δθ of a-Si:H increased due to dehydrogenation. Ion implanted a-Si contained only small vacancies of which size was the same as that of the divacancy in crystalline Si, which were dissociated and annihilated during annealing. On the other hand, both evaporated a-Si and ECR CVD a-Si:H contained larger vacancies, and nanometer-size vacancy clusters were formed during the annealing processes, more significantly in ECR CVD a-Si:H.
Based on these experimental results, we concluded that large vacancies tend to form vacancy clusters or microvoids which suppress structural relaxation in a-Si.
Structural Investigation of Gold Induced Crystallization in Hydrogenated Amorphous Silicon Thin Films
Authors: Ashtikar M. S. , G. L. Sharma G. L. Sharma
Published: October 2002

Thin bilayers of glow discharge produced hydrogenated amorphous silicon (a-Si:H) and vacuum evaporated gold were annealed at different temperatures to investigate the metal induced crystallization of a-Si:H. The process of crystallization was studied by Transmission Electron Microscopy and Electron Diffraction, Auger electron spectroscopy (AES), glancing angle X-ray diffraction (XRD) and Raman spectroscopy. The results indicate that the crystallization of silicon is mediated via formation of two randomly dispersed metastable phases of gold silicide in the host matrix. Both the silicides were found to have cubic symmetry with the same lattice constant of 6.52 Å. These silicides first appear at 130° C and are stable up to 170° C. Between 170-200° C the silicides dissociate to form polycrystalline silicon.
Distributions of Thermal-Annealing Activation Energies for Light-Induced Spins in Fast and Slow Processes in a-Si1-xNx:H Alloys
Authors: Zhang Jinyan , Kumeda Minoru , Tatsuo Shimizu Tatsuo Shimizu
Published: October 2002

We report on the thermal annealing of light-induced neutral dangling bonds (DB's) created by strong band-gap illumination at 77 K and room temperature (RT) in amorphous silicon-nitrogen alloys ( a-Si1-
x

N

x

:H). We find that the light-induced DB's are annealed out with distinct distributions of annealing activation energies (E
A's). The distribution for the light-induced DB's created in the fast process (FDB's) and the one for those created in the slow process (SDB's) are separated unambiguously: E
A for FDB's is in the range from 0 to 0.7 eV, in which two separated peaks (centered at about 0.09 and 0.4 eV) are embodied, and E
A for SDB's is in the range from 0.6 to 1.4 eV, centered at about 1 eV, in a-Si0.5N0.5:H. Moreover, the results demonstrate that the distributions of E
A for FDB's and SDB's depend on illumination temperature and illumination time.
Flow Coupled Switching Equations for Surface-Stabilized Ferroelectric Liquid Crystal Cells
Authors: Zou Zhong , Carlsson Noel A. Clark and Tomas
Published: October 2002

Flow-coupled switching equations are derived for surface-stabilized ferroelectric liquid crystal devices, starting from Leslie, Stewart and Nakagawa's continuum theory for smectic C liquid crystals. Comparisons with nematic like dynamic equations are made.