bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Properties of Pb(Zr,Ti)O 3 Thin Film Capacitors on Pt and Ir Electrodes
Authors: Takashi Nakamura Takashi Nakamura , Yuichi Nakao Yuichi Nakao , Akira Kamisawa Akira Kamisawa , Hidemi Takasu Hidemi Takasu
Published: October 2002

Pb(ZrxTi1-x
)O3 (PZT) thin films were prepared on Ir/IrO2 and Pt/IrO2 electrodes. We have already reported that fatigue properties of PZT thin films were improved by using these electrodes due to barrier effects of IrO2. In this present paper we describe a study of the imprint characteristics of PZT thin films on these electrodes. There is little difference in fatigue properties between the PZT films on Pt/IrO2 and Ir/IrO2. However, we find some difference in imprint characteristics between the PZT films on these electrodes. In the case of Ir/IrO2 electrode, improvements in the electrical properties are observed in the measurements of the imprint characteristics. Moreover, improvements in imprint characteristics were also obtained with good (111)-axis orientation of PZT films when PtxIr1-x
/IrO2 electrodes were used.
Effects of O2 Gas Pressure in Heat Treatment on Surface Morphology and Electric Properties of Ferroelectric Bi4Ti3O12 Thin Films with c-Axis Orientation
Authors: Kakimi Atsushi , Okamura Soichiro , Ando Shizutoshi , Takeyo Tsukamoto Takeyo Tsukamoto
Published: October 2002

Fabrication of ferroelectric Bi4Ti3O12 thin films was carried out by spin-coating pyrolysis of Bi and Ti naphthenates and successive heat treatment in O2 gas at various pressures. Heat treatment in O2 gas at high pressure was effective for the fabrication of c-axis oriented Bi4Ti3O12 thin films with a smooth surface and improvement of their electric properties. The thin film heat-treated at the O2 gas pressure of 4.0×105 Pa was a single phase of Bi4Ti3O12 completely oriented along the c-axis with good ferroelectric properties at room temperature: coercive field of 23 kV/cm, remanent polarization of 1.9 µ C/cm2, dielectric constant of 45, loss of 0.01 and leakage current density on the order of 10-9 A/cm2. The remanent polarization of the thin film was kept constant up to the polarization reversal at 1×107 cycles.
Crystalline Quality and Electrical Properties of PbZrxTi1-xO3 Thin Films Prepared on SrTiO3-Covered Si Substrates
Authors: Tokumitsu Eisuke , Itani Kensuke , Moon Bum-Ki , Hiroshi Ishiwara Hiroshi Ishiwara
Published: October 2002

We report the crystalline quality and electrical properties of PbZr

x

Ti1-
x

O3 (PZT) films grown on Si substrates with a SrTiO3 (STO) buffer layer. STO buffer layers and PZT films were formed on Si substrates by the electron-beam assisted vacuum evaporation technique and the sol-gel technique, respectively. It is shown that by using a thin (8 nm) metal Sr layer or fluoride ( SrF2, CaF2) predeposition layers prior to the STO deposition, which reduces the SiO2 layer at the Si surface, highly oriented STO and PZT thin films can be grown on Si(100) and (111) substrates. Crystalline orientation of the PZT films strongly depends on the crystalline orientation of the STO buffer layers. It is also shown that the full width at half-maximum (FWHM) values of X-ray diffraction (XRD) peaks from PZT films are strongly related to those of STO buffer layers. Furthermore, the capacitance-voltage characteristics and current response measurements indicate the ferroelectric nature of PZT films grown on STO-covered Si substrates.
Properties of Ferroelectric Pb(Zr, Ti)O3 Thin Films on TiSi2/Si Substrates
Authors: Hatano Hitoshi , Okamura Soichiro , Ando Shizutoshi , Takeyo Tsukamoto Takeyo Tsukamoto
Published: October 2002

A titanium disilicide ( TiSi2) layer was prepared on Si wafers by Ti evaporation on Si in vacuum followed by heat treatment at 800° C. The sheet electrical resistance of the TiSi2 layer was estimated to be 1.3 Ω/\Box at room temperature. Ferroelectric Pb(Zr, Ti)O3 thin films was then fabricated on TiSi2/Si by “the spin-coating pyrolytic process”, here and throughout using Pb, Zr and Ti naphthenates. The remanent polarization and coercive field of the PZT film were estimated to be about 0.4 µ C/cm2 and 97 kV/cm, respectively. The potential of the TiSi2 layer as electrodes for capacitors in a VLSI was demonstrated.
Propagation Characteristics of Leaky Surface Acoustic Waves and Surface Acoustic Waves on LiNbO 3 Substrates with a Ferrroelectric Inversion Layer
Authors: Kiyoshi Nakamura Kiyoshi Nakamura , Ailie Tourlog Ailie Tourlog
Published: October 2002

The propagation characteristics of the leaky surface acoustic wave (LSAW) propagating on rotated Y-X lithium niobate (LiNbO3) substrates with a ferroelectric inversion layer are theoretically analyzed. The results show that the attenuation of the LSAW on 41° Y-X LiNbO3 is smaller than 10-5 dB/wavelength over a range of k
h (k: wave number, h: inversion-layer thickness) from 2 to 2.5 for both free- and metallized-surface cases, and that the phase velocity of the LSAW is decreased and the concentration of the displacement to the surface is improved by the electric-field short-circuiting effect of the domain boundary. The propagation characteristics of the surface acoustic wave on 128° Y-X LiNbO3 substrates with an inversion layer are also reported.
Electromechanical Properties of Composite Bending-Type Transducers
Authors: Masakazu Marutake Masakazu Marutake , Masaru Yokosuka Masaru Yokosuka
Published: October 2002

A composite bending-type transducer is proposed for the purpose of measuring the elastic compliance constant of nonpiezoelectric material at rather low frequencies. It consists of two thin plates with different thicknesses, bonded together, of which one is piezoelectric and the other is nonpiezoelectric. We can calculate the elastic compliance constant of the nonpiezoelectric material from the value of the resonance frequency of the transducer obtained from the measurement of its electrical admittance, together with the electromechanical coupling factor and the elastic compliance constant of the piezoelectric driver. In this paper, the resonance frequency of the transducer is calculated in the general case, and the experimental results are shown in some simple cases. The measurements of the elasticity of nonpiezoelectric materials will be reported in the future.
Electric Properties of Pb(Sb1/2Nb1/2)O3-PbTiO3-PbZrO3 Ceramics Modified with Certain Additives
Authors: Ohuchi Hiromu , Yasushi Kawamura Yasushi Kawamura
Published: October 2002

Effects of additives on the ceramic and electric properties of Pb(Sb1/2Nb1/2)O3-PbTiO3-PbZrO3 ceramics in a perovskite-type structure were investigated. Addition of small amounts of MnO2 or NiO increased the sintered density. However, larger amounts of MnO2 or NiO lowered the sintered density. Small amounts of MnO2 or NiO promoted the grain growth of the ternary base composition. The microstructure indicated that small amounts of MnO2 produced a fine, uniform grain structure and addition of NiO produced clearer grain boundaries and larger grain size than MnO2 addition. The resistivity, dielectric and piezoelectric properties of the base composition were improved markedly through selection of additives in proper amounts. High mechanical quality factor, Q
M (2070), low dielectric dissipation factors (36×10-4) and high radial coupling coefficient, k
p (54%) were obtained by addition of MnO2.
Direct Observation of Photoinduced Gratings in LiNbO3:Fe Single Crystals Using a Scanning Electron Microscope
Authors: Chiku Shinichiro , Horiuchi Toshihisa , Shiosaki Tadashi , Matsushige Kazumi
Published: October 2002

Charge gratings induced in LiNbO3:Fe single crystals in which photorefractive gratings had been formed by means of two-wave mixing of laser beams were directly observed using a scanning electron microscope (SEM). The gratings were found in both the surface defects and cleavage planes of the crystals and their wave vectors corresponded well with those of the interference fringes made by two laser beams. It was also suggested that the profiles of the gratings agree with the nonsinusoidal functions derived from theoretical calculations. Moreover, the formation mechanism of the charge gratings was discussed.
Polarization Reversal Process and Transient Light Scattering in Polymeric Ferroelectric Liquid Crystal
Authors: Hiroshi Moritake Hiroshi Moritake , Yoshiaki Fuwa Yoshiaki Fuwa , Masanori Ozaki Masanori Ozaki , Jenn Chiu Hwang Jenn Chiu Hwang , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Two types of electrooptic effects, a transient scattering mode (TSM) effect at the instant of polarity reversal of applied voltage and a deformation of helical structure (DHS) effect upon applying stepwise voltage in poly[((2S,3S)-3-methyl-2-chloropentanoic acid-4',4"-undecyloxybiphenyl ester)methylsiloxane] (P3M2CPUOB) have been studied. The response times of the TSM and DHS effects decrease with increasing applied field and temperature. A stripe pattern parallel to the smectic layer has been observed at the instant of polarity reversal. This stripe pattern has been maintained after removal of pulse voltage. Characteristics of the optical switching utilizing this stripe pattern and the DHS effect have been discussed.
Electrooptical and Nonlinear Optical Effects in Free-Surface Films of Polymeric Ferroelectric Liquid Crystals Prepared by Spin-Coating Method
Authors: Skarp Kent , Helgee Sadahito Uto , Katsumi Yoshino Katsumi Yoshino
Published: October 2002

Well-aligned thin films of polymeric ferroelectric liquid crystal have been prepared by means of a spin-coating method. Several types of electrooptical effects and the optical second-harmonic generation in these films have been measured. The characteristics of their effects in spin-coated polymeric ferroelectric liquid crystal film with a free surface have been discussed in comparison with those of conventional sandwich cells.
Transient Analysis of Minority Carrier Diffusion in the Base of P/N Junction Diodes and Bipolar Transistors
Authors: Hasselbeck M. P. , J. J. Liou J. J. Liou
Published: October 2002

The time-dependent minority carrier distribution in the base of a bipolar p/n junction subjected to a step-up or step-down (switch-on or switch-off) applied voltage has been obtained. Analytical expressions are found by solving the time-dependent minority-carrier diffusion equation with appropriate boundary conditions. A general case with arbitrary base width under both switch-on and switch-off transients is considered. In addition, the validity of the constant-voltage and constant-current approaches under different base widths and different bias conditions are also discussed. This analytical approach is also applied to obtain the turn-on current transients of a forward-active bipolar transistor. The results are compared with those simulated from the conventional Gummel-Poon model and obtained from measurement.
Refractive Index Variation in GaInAsP/InP Quantum Confined Structures Grown by Chemical Beam Epitaxy
Authors: Kurita Yoichiro , Yokouchi Noriyuki , Miyamoto Tomoyuki , Koyama Fumio , Kenichi Iga Kenichi Iga
Published: October 2002

The absorption coefficient and refractive index variations due to quantum confined Stark effect in a GaInAsP/InP multiple quantum well grown by chemical beam epitaxy have been investigated. The refractive index variation was estimated from the variation of the optical absorption coefficient spectra for various electric fields. The optical absorption coefficient spectra was directly measured by transmission experiments. The maximum refractive index variation was estimated to be 3% at an applied reverse bias voltage of 3 V.
Photoluminescence Investigation of Doped Asymmetric Coupled Quantum Wells
Authors: Huibing Mao Huibing Mao , Jiaming Zhang Jiaming Zhang , Wei Lu Wei Lu , Shuechu Shen Shuechu Shen
Published: October 2002

We report in this paper the photoluminescence (PL) investigation of a partly doped asymmetric coupled quantum well (ACQW) structure. The dependence of non-resonant tunneling rate on excitation power for different Al0.28Ga0.72As interbarrier thicknesses is studied in detail. The PL intensity from a 20 nm Al0.2Ga0.8As well is much larger than that from a 5.5 nm Si-doped GaAs well when the interbarrier is thick (>12 nm). This result indicates that photo excited carriers are preferentially relaxed toward the wide well, which has larger state density than the doped narrow well. The competition among different processes of intersubband relaxations is discussed in connection with the PL spectra.
Electroabsorption Study of Ferroelectric Polymer
Authors: Kazushige Hasegawa Kazushige Hasegawa , Akihiro Tomioka Akihiro Tomioka , Kenjiro Miyano Kenjiro Miyano , Iwao Seo Iwao Seo
Published: October 2002

Electroabsorption of probe dye molecules has been used to monitor the electric field inside and outside a ferroelectric film consisting of a copolymer of vinylidene fluoride and trifluoroethylene. The local-field factor inside the ferroelectric film was found to be relatively low and is in good agreement with a previous numerical simulation. On the other hand, the field outside is much larger and thus more advantageous to use in applications. The latter field was used to demonstrate the readily observable Stark effect without signal averaging.
Electromechanical Properties of Relaxor Ferroelectric Lead Magnesium Niobate-Lead Titanate Ceramics
Authors: Zhao J. , Zhang Q. M. , Kim N. , T. Shrout T. Shrout
Published: October 2002

In this paper, the results of a recent investigation of the dependence of the induced piezoelectric activity on temperature, electric bias field, and frequency and the electrostrictive response in the relaxor ferroelectric lead magnesium niobate-lead titanate ceramics ( (1- x)(Pb(Mg1/3Nb2/3)O3)- x(PbTiO3)) at compositions below 30% PT are presented. It was observed that the electrostrictive strain at temperatures near the dielectric constant maximum T
max increases monotonically with increased PT content. For PMN:PT at compositions near 30% PT, the electrostrictive strain under a 10 kV/cm electric field can reach about 0.15% with very little hysteresis. An exceptionally large piezoelectric response with an effective piezoelectric d
33 coefficient in the electric field induced state of over 1,800 pC/N could be achieved for selected PMN:PT compositions and electric bias fields.
Detection and Identification of Near-Surface Microprecipitates in Silicon Wafers by Laser Scattering Tomography
Authors: Moriya Kazuo , Yazaki Akira , Katsuyuki Hirai Katsuyuki Hirai
Published: October 2002

A nondestructive measurement system for characterizing near-surface (0 to 100 µ m) microprecipitates in silicon wafers using laser scattering tomography has been developed. A near-infrared laser beam (λ=1 µ m) is focused to about 4 µ m in diameter and introduced into the wafer from an inclined direction through the polished surface. The scattered light is also observed from the polished side. The scattered light has a complicated signal, because the scattered light from the near-surface microdefects, that from the haze related to the surface microroughness, and that from the dust on the surface are mixed. By using a polarization analysis method, the scatterings from the haze, dust and microdefects are clearly distinguished. The scattering from the subsurface (0 to 5 µ m) region is also identified as that due to dust and microprecipitates by using a short-wavelength laser (λ=680 nm).
Model Analysis of Current-Mode Images of Highly Oriented Pyrolytic Graphite by Scanning Tunneling Microscope in Air
Authors: Hiroyuki Nishikawa Hiroyuki Nishikawa , Hiroaki Shiba Hiroaki Shiba , Takeo Iri Takeo Iri
Published: October 2002

The current-mode images of highly oriented pyrolytic graphite (HOPG) by scanning tunneling microscope (STM) in air were analyzed in detail by a simple model of the tip and the graphite surface. It was found that the tunneling current is comprised of two components. One is the current through an atom at the top of the tip, which essentially defines the resolution of STM images. The other is the current through the other part of the tip in contact with the sample surface as a result of the elastic deformation of the sample, which becomes dominant in the case of low tunneling resistance. The latter could be explained on the assumption that the tunneling current is proportional to the contact area estimated from the penetration distance of the tip. It was found that the effective tip-sample separation can be modified through the deformation of the intermediate layer on the sample surface.
Evaluation of Ultrathin Si Growth Layer on W, Mo, and Ta Surfaces with In Situ Field Emission and Field Ion Microscopies
Authors: Kimio Okuno Kimio Okuno
Published: October 2002

Ultrathin Si films vapor-deposited onto W, Mo and Ta surfaces and Si-metal interface properties have been evaluated with microscopic-capability in situ field emission and field ion microscopies (FEM-FIM). Work functions of W, Mo, and Ta substrates covered with a Si monolayer were found to be 4.8 eV, 4.6 eV and 4.5 eV, respectively. The Si monolayer adatoms deposited onto the W and Mo surfaces at around 50 K are field-desorbed at voltages greater than 0.9V
0 (V
0: evaporation voltage of substrate). The clean surfaces of the W and Mo substrates finally appeared at V/V
0=0.96-0.98, and the Si films were found to be desorbed without defects or disturbance of the substrate atomic structure. Silicon-metal intermixing was therefore not detected in the case of Si vapor deposition at around 50 K.
The dynamical behavior of Si atoms due to thermal annealing was also examined.
Spatial Distribution and Transport of an Electron Cyclotron Resonance Plasma Generated Using Dominant-Mode Microwave
Authors: Watanabe Seiichi , Furuse Muneo , Usui Takehito , Kawasaki Sunao
Published: October 2002

The relationship between the plasma uniformity and the microwave electric field was investigated for various levels of microwave power by introducing only the dominant-mode microwave: either the circular TE11mode or the rectangular TE10mode. The plasma uniformity was found to change in three stages according to the electron density depending on the microwave transmission characteristics in the plasma. The fluctuations of the plasma emission were also investigated in several types of discharges. A fixed spatial distribution of the microwave electric field was found to be effective for stabilizing the plasma. The high-density plasma above 1×1011cm-3was found to be more stable.
High-Performance Stimulating Coils and Eddy Currents in Magnetic Heart Stimulation
Authors: Kubota Hiroshi , Wada Shigeru , Maita Soichiro , Yamamoto Isao , Yamaguchi Masuhiro , Andoh Tomio , Kawakami Tadashi , Okumura Fukuichiro , Takenaka Toshifumi , Goto Tsuneaki
Published: October 2002

Effective stimulating coils were developed for magnetic excitation of cardiac muscle, and eddy currents produced by the coils were observed and calculated. The coils were flat solenoids made from beryllium-copper alloy, having a structure at satisfactory mechanical strength. Two coils were effectively combined to intensify stimulus fields in a target heart. The spatial distribution of the eddy current density was measured for a cylindrical volume filled with saline solution which was adopted as a model of the canine body. The result agrees well with the eddy current density calculated by the finite difference method. The performance of the present coil system is discussed from the point of view of magnetic defibrillation.
Influence of Surface Melt Flow on Oxygen Inhomogeneity in Czochralski-Grown Silicon Single Crystal: Studied by Double-Layered Czochralski (DLCZ) Melt Quenching Technique
Authors: Kawanishi Soroku , Togawa Shinji , Izunome Koji , Terashima Kazutaka , Shigeyuki Kimura Shigeyuki Kimura
Published: October 2002

The oxygen incorporation mechanism at the growth interface during Czochralski (CZ) silicon single crystal growth has been studied using melt quenching technique developed by the double-layered Czochralski (DLCZ) process. A slow crystal rotation rate of 0.5 rpm was chosen to investigate the influence of melt convection in relation to the source of oxygen on the oxygen inhomogeneity in the grown crystal. Micro-Fourier transform infrared spectroscopy (micro-FTIR) measurement and preferential etching revealed that the oxygen variation in the crystal was determined by the balance of the bulk melt with a high oxygen content and the oxygen-depleted melt from the free surface. The major cause of the periodic intake of the oxygen-depleted melt flow during one crystal rotation was probably the inhomogeneous radial temperature gradient. This suggests that thermal asymmetry in the melt is a fatal factor in oxygen inhomogeneity in the crystal. We have postulated that the equilibrium oxygen segregation coefficient is not much smaller than unity, but is rather close to it.
EL2 Defect Metastability-Related Transients Revisited
Authors: Radić Nikola , Š Branko , Uroš V. Desnica Uroš V. Desnica
Published: October 2002

Closed-type solutions of the basic model for photoinduced metastable transformation of the EL2 centers in SI GaAs are studied. Conditions for the existence of maximum in the optical absorption α, photocapacitance C
d, and electron paramagnetic resonance (EPR) transients are determined. Several methods for the estimation of the initial neutral EL2 fraction (occupancy f), and cross-section for the metastable transformation σ* from the dynamics of “fingerprint” transients are proposed, and the accompanying ready-to-use nomograms computed and presented.
Optical Properties of SnTe
Authors: Suzuki Norihiro , Sadao Adachi Sadao Adachi
Published: October 2002

The real (ε1) and imaginary (ε2) parts of the complex dielectric function,ε(E)=ε1(E)+ iε2(E), of SnTe have been measured by spectroscopic ellipsometry (SE) in the 1.15-5.5 eV photon-energy range at room temperature. The measured SE spectra reveal distinct structures at energies of E1, E2and E3critical points. These data are analyzed using two theoretical models, namely, the model dielectric function (MDF) and standard critical-point (SCP) model. It is found that both the MDF and SCP models successfully explain the first-derivative spectra ofε(E) [ dε(E)/ dE]. The MDF also shows excellent agreement with the experimentalε(E) spectra, but the SCP does not. Dielectric-related optical constants, such as the complex refractive index (n*=n+ ik), absorption coefficient (α) and normal-incidence reflectivity (R), of SnTe are also presented.
Effects of Tin Concentrations on Structural Characteristics and Electrooptical Properties of Tin-Doped Indium Oxide Films Prepared by RF Magnetron Sputtering
Authors: Yi Choong Hoon , Yasui Itaru , Yuzo Shigesato Yuzo Shigesato
Published: October 2002

Structural characteristics and electrooptical properties of Sn-doped In2O3(ITO) films were investigated in terms of Sn concentrations from 5.34 to 8.99 (Sn/In at.%) with changing oxygen partial pressure and substrate temperature during deposition, in spite of using an ITO target with the same Sn concentration ( 7.50 SnO2wt%, 7.17 Sn/In at.%). The resistivity of the films deposited at 200 and 300° C had a clear tendency to decrease with decrease of the total Sn content. Sn atoms incorporated in the ITO films were classified into two types, i.e., electrically active substitutional Sn atoms contributing to carrier density and electrically nonactive impurities forming nonreducible tin-oxide complexes, which were revealed by precise lattice constant measurement. The change in the Sn concentration was found to be associated with the preferred orientation of the crystal grains, which was dominated by the deposition conditions and should reflect the crystal growth processes.
Characterization of LiNbO3 Optical-Waveguide Film Grown on Sapphire by ArF Excimer Laser Ablation
Authors: Haruna Masamitsu , Ishizuki Hideki , Tsutsumi Jun , Shimaoka Yusaku , Hiroshi Nishihara Hiroshi Nishihara
Published: October 2002

Heteroepitaxial growth of LiNbO3 film is expected to provide a novel hybrid integration of optical and electronic components and devices. In this paper, we present, for the first time, to our knowledge, characterization of LiNbO3 optical-waveguide film grown on c-cut sapphire by ArF excimer laser ablation. Almost droplet-free LiNbO3 film was deposited only by increasing the target-to-substrate distance d to 40 mm, where Li-rich LiNbO3 ceramics with the Li/Nb ratio of 2.1 was used as the target. The deposited LiNbO3 film also exhibited a strong (006) peak in the X-ray diffraction spectrum, showing good orientation along the c axis. Optical properties were characterized based on excitation of guided modes in the film with a prism coupler. The propagation loss of the TM0 mode was lowered to be 5 dB/cm at λ=0.633 µ m. The film indices were exactly determined, followed by evaluation of the chemical composition of the film from the measured index n
e of the extraordinary wave. Lack of Li2O in the film became more significant as the distance d increased. A Bragg light deflector was then fabricated to evaluate the electrooptic coefficient r
33 in the film deposited under the condition that d=40 mm. r
33 was found to be as large as 4.9 pm/V, which was nearly one-sixth of the single-crystal value, irrespective of nonstoichiometry of the film.
Digitally Signal-Regenerating Optical-Fiber Loop Memory with Side-Injection-Light-Controlled Bistable Laser Diode
Authors: Nonaka Koji , Tsuda Hiroyuki , Takashi Kurokawa Takashi Kurokawa
Published: October 2002

A signal-regenerating optical-fiber loop memory with a side-injection-light-controlled bistable laser diode exhibiting thresholding gain characteristics is demonstrated. This system digitally regenerates memorized signals bit by bit. Output signals with a high on/off ratio of around 20 dB and stable intensity levels with less than 7% fluctuation are obtained even after 100 circulations.
Role of Minority-Carrier Diffusion in Photoreflectance Measurements of Epitaxial GaAs Wafers
Authors: Mochizuki Yasunori , Ishii Toshihiro , Masashi Mizuta Masashi Mizuta
Published: October 2002

Minority-carrier diffusion, instead of direct penetration of pump light, can be a dominant factor which determines the probed region in photoreflectance measurements of epitaxial GaAs wafers. Appearance of Franz-Keldysh oscillations (FKOs) originating from epitaxial layer/substrate interfaces is found to critically depend on the penetration depth of pump light relative to the surface depletion-layer width. This relationship indicates the importance of generation and diffusion of minority carriers within the neutral region, which can induce photoreflectance from unexpectedly deep locations. By inserting a potential barrier (a doped AlAs layer) into the path for minority-carrier diffusion, such a FKO component is shown to be eliminated. The experiment confirms that the sample under study is indeed in the diffusion-limited regime, and at the same time, provides a simple method which allows an accurate evaluation of the FKOs from the doped region (surface depletion layer), which usually is of interest from technological aspects.
Influence of Alkali Ions in Enhancing the Nonlinearity of ZnO-Bi2O3-Co3O4 Varistor Ceramics
Authors: Kutty T. R. Narayanan , S. Ezhilvalavan S. Ezhilvalavan
Published: October 2002

Zinc oxide ceramic varistors with simplified compositions of ZnO+Bi2O3+Co3O4+M2O (M=K or Na) show nonlinearity coefficients (α) of 40-75. The electron paramagnetic resonance spectra and optical reflectance spectra show that there is a direct interdependence between the oxidation state of transition metals and the alkali ions. The X-ray photoelectron spectra indicate that the alkali ions preserve a higher oxidation state of cobalt, Co(III), in the grain boundary regions than in the grain interiors having more Co(II). Admittance spectroscopy shows that, while the nature of traps remains unaltered, the trap density increases with the concentration of alkali ions near the interface. The observed defect states are associated with the grain bulk than with the grain boundary interfaces, as indicated by the isothermal capacitance transient signals.
Local Distortion and Chemical Surroundings of NiO6 Octahedra for Ni(III) Oxides with K2NiF4-Type Structure
Authors: Byeon Song-Ho , Demazeau Gérard , Choy Jin-Ho
Published: October 2002

Ni(III) oxides with the K2NiF4-type structure, (A, A′)2M0.5
′Ni0.5O4 ( A′=alkaline earth, A=rare earth, and M′=Mg, Zn, Ti, Al, Ga) have been prepared under high oxygen pressure ( ∼150 MPa). The evolution of the local distortion of NiO6 octahedra in such lattices was studied using X-ray diffraction analysis (XRD), electron paramagnetic resonance (EPR) and infrared (IR) spectroscopies. The observed distortions are discussed on the basis of covalency and relative strength of the axial [ (A′, A)-O] and equatorial ( M′-O) competing bonds surrounding the NiO6 octahedron in the lattice. These results are related to the structural tolerance factor proposed by Poix.
Sub-Atomic Layer Growth of SiC at Low Temperatures
Authors: Eiichi Sadayuki Eiichi Sadayuki , Shigeru Imai Shigeru Imai , Masakiyo Matsumura Masakiyo Matsumura
Published: October 2002

Sub-atomic layer growth of SiC has been achieved using diethylsilane ((C2H5)2SiH2) by resolving elemental kinetics of its chemical vapor deposition. The growth rate of 0.1 monolayer/cycle was obtained over the temperature range between 590°C and 675°C. The detailed growth characteristics, the composition of the grown film, and the surface morphology have been presented. The initial growth and the coverage of the grown film were also investigated by X-ray photoelectron spectroscopy.
Effect of Etching on Composition and Morphology of CdTe(111) Surfaces
Authors: Yang Tian-Juh , Tai-Bor Wu Tai-Bor Wu
Published: October 2002

Various surface treatments, including wet chemical etching, heat treatment in H2 and sputter etching with Ar ion, were applied to CdTe(111) surfaces. The induced surface layer and morphology were studied with angle-resolved X-ray photoelectron spectroscopy (ARXPS), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). For wet chemical etching, both Br/methanol and KOH/methanol resulted in a Te-enriched surface, while the Te-rich layer induced by Br/methanol etching can be at least partially removed by treating with reducing etchants including hydrazine and dithionite. A hillock like morphology was the common feature of these wet-chemically etched surfaces. After hydrogen heat treatment, both Cd(111) and Te(111) surfaces were Cd-rich and a distinct difference in microscopic morphology between the Cd(111) and the Te(111) surfaces was observed. The surface morphology developed by hydrogen heat treatment can be used to identify the crystal polarity. The sputter etching caused compositional changes in the surface of CdTe(111), resulting in Te enrichment at the outermost layer but Te depletion in the subsurface region. Also, an Ar-ion-energy-dependent surface morphology was observed.
RF Selfbias Voltage and Sheath Width in Inductively Coupled Chlorine Plasma
Authors: Shindo Haruo , Fukasawa Takayuki , Nakamura Akihiro , Horiike Yasuhiro
Published: October 2002

Radio frequency (RF) self-bias was systematically measured in an inductively coupled Cl2 plasma and it was compared with the theory previously reported for the negative ion containing plasma. Measured RF self-bias was easier to build up at lower RF source power, and this is simply because the negative chlorine ion relatively increases and thus the sheath width becomes larger in this condition. The experimentally determined sheath width was found to be consistent with the theory.
Experimental Studies on 70 GHz Slow Surface Wave Propagation in Transversely Magnetized Partially Filled Ring-Form Solid-Plasma Waveguide
Authors: Kimura Noritoshi , Ishizuka Takehiko , Tetsuo Obunai Tetsuo Obunai
Published: October 2002

70 GHz slow wave propagation characteristics in a transversely magnetized partially filled ring-form solid-plasma waveguide have been studied experimentally employing n-type InSb ring at liquid nitrogen temperature as the plasma material. Obtained results were compared with those for the previously studied straight parallel-plate configuration. It is clearly shown that the surface wave resonance corresponding to the one observed in the straight plasma waveguide takes place also in the curved structure, and the propagation characteristics are quite similar to those of the straight configuration. Reduction of the resonant magnetic field is found with increasing the curvature of the waveguide.
Comparison of Device Performance in Two Thin-Film Electroluminescent Devices Made of Vacuum-Sublimed Dye Film and Spin-Coated Polymer Film
Authors: Kim Dong Uk , Aminaka Ei-ichiro , Tsutsui Tetsuo , Shogo Saito Shogo Saito
Published: October 2002

Electroluminescent (EL) characteristics in EL devices made of vacuum-sublimed dye films and spin-coated polymer films were compared. Low-molar-mass dye, 9,10-bis[4-(N,N-diphenylamino)styryl]anthracene (dye-BSA), for the preparation of vacuum-sublimed films, and polymer with 9,10-bis[4-(N,N-diphenylamino)-styryl]anthracene chromophore linked with alkylether groups (polymer-BSA) were employed. Single-layer devices, indium-tin oxide (ITO)/dye-BSA/MgAg and ITO/polymer-BSA/MgAg were prepared, and EL performances were compared. Double-layer devices which have an oxadiazole derivative (OXD-7) electron transport layer, ITO/dye-BSA/OXD-7/MgAg and ITO/polymer-BSA/OXD-7/MgAg, were also prepared. The current density-voltage relationships between dye-BSA devices and polymer-BSA devices were considerably different mainly due to the poor film quality of polymer-BSA.
The comparisons of the luminance-current density relationships of the devices with two classes of BSA films showed that the polymer-BSA devices exhibited similar EL characteristics as the dye-BSA devices in the region of current density higher than 10 mA/cm2. The possibility of the use of common material design concept for low-molar-mass materials and polymers was discussed.
A New High-Density Plasma Etching System Using A Dipole-Ring Magnet
Authors: Sekine Makoto , Narita Masaki , Horioka Keiji , Yoshida Yukimasa , Haruo Okano Haruo Okano
Published: October 2002

A new high-density plasma etching system has been developed using a dipole-ring magnet (DRM). The system utilizes a parallel magnetic field up to 600 G with excellent uniformity extending over 250 mm in diameter. The nonuniformity of plasma was compared with that of a conventional permanent-magnet-enhanced plasma using a gate oxide integrity test. The plasma generated using DRM produced no gate oxide degradation, while the conventional magnetron plasma produced some gate oxide degradation under the most highly accelerated conditions. Si etch rate is shown to depend strongly on magnetic field strength, increasing from 1.3 µm/min at 120 G to 2.1 µm/min at 600 G.
Plasma-Polymerized Chlorinated \mbα-Methylstyrene (PP-C-\mbαMS): A High Performance Negative Electron Resist
Authors: Gosavi Suresh , Gangal S. A. , Kuruvilla Beena Annie , Kulkarni S. K.
Published: October 2002

This paper presents some preliminary results on improvement in the e-beam sensitivity of plasma-polymerized α-methylstyrene (PP-αMS) resist, by chlorination. Electrodeless glow discharge polymer films of α-methylstyrene (PP-αMS) and chlorinated α-methylstyrene (PP-C-αMS) are synthesized by using the standard Ar gas flow reactor under different deposition conditions. Polymer composition and its structure are evaluated using XPS and FTIR techniques. Elemental analysis of the films is carried out for the estimation of chlorine concentration. The evaluation as e-beam resist of PP-αMS and PP-C-αMS is made by electron beam mask fabricator (EBMF 2.5). The sensitivity (D

n

0.5) of PP-αMS for 20 kV electrons is 1000 µC/cm2. Addition of ≈4.0% chlorine in the polymerization process increases the sensitivity to 1.0 µC/cm2. Further, the sensitivity of (PP-C-αMS) is found to be a function of chlorine content. This material exhibited a 1 µm-resolution line-and-space pattern.
Effects of Rapid Thermal Annealing on Si Delta-Doped GaInP Grown by Low Pressure Metalorganic Chemical Vapor Deposition
Authors: Wang Chien-Jen , Feng Ming-Shiann , Chan Shih-Hsiung , Wu Janne-Wha , Chang Chun-Yen , Simon Min Sze Simon Min Sze
Published: October 2002

We have investigated the effects of rapid thermal annealing on the Si delta-doped GaInP.
The spatial localization of carriers was derived and used to determine the diffusion coefficient of Si in GaInP by the capacitance-voltage measurement. We found an unusual mobility change of Si delta-doped GaInP after annealing from Hall-effect measurement. The compensation effect of Si amphoteric property could not be used to explain this behavior. From photoluminescence spectra, it is suggested that the ordered/disordered transformation is the dominate factor for mobility increase after annealing. On the contrary, the degradation of quantum confinement in delta-doped structure by dopant diffusion after annealing is responsible for the decrease of mobility. Therefore, the behavior of mobility could be considered as a competition result of these two mechanisms.
Fabrication of Antenna-Coupled Microbolometers
Authors: Shimizu Takashi , Moritsu Haruhito , Yasuoka Yoshizumi , Gamo Kenji
Published: October 2002

Fabrication conditions of antenna-coupled microbolometers which function in the far-infrared (FIR) frequency region are discussed. A bow-tie antenna-coupled microbolometer was fabricated on a 300 nm Si3N4 membrane, and detection experiments for 118 µ m CH3OH laser radiation were performed. The measured antenna pattern indicated that the fabricated device functions as an antenna-coupled device which receives the laser radiation by means of the antenna and detects its power by means of the microbolometer. The responsivity of the microbolometer for 118 µ m CH3OH laser radiation was 56 V/W at the bias current of 0.6 mA.
Although this value was 1 dB less than that of DC responsivity, we obtained conclusive evidence that the fabricated bismuth microbolometer can be utilized as a detector for a FIR receiving antenna.
Microstructure and Nonohmic Properties of ZnO-V2O5 Ceramics
Authors: Tsai Jyh-Kuang , Tai-Bor Wu Tai-Bor Wu
Published: October 2002

The microstructure and nonohmic characteristics of polycrystalline ZnO-V2O5 ceramics with V2O5 as the only additive ranging from 0 to 2 mol% were investigated. An abnormal grain growth was observed for ZnO doped with V2O5 and sintered at 900° C. However, the non-uniformity of the grain structure alleviated with increasing the V2O5 content or sintering temperature. The ZnO-V2O5 ceramics have shown characteristics of nonohmic V-I behavior and large apparent dielectric constant with a relaxation peak of 0.36 eV at 300 kHz. The electrical properties of these ZnO-V2O5 ceramics depended strongly on the processing conditions and V2O5 content, and there seems a close relation between the nonlinear electric properties and the concentration of the deeply-trapped defects at 0.36 eV in ZnO.
Use of Mixture Equations for Estimating Theoretical Complex Permittivities from Measurements on Porous or Powder Ceramic Specimens
Authors: Arai Masayuki , Binner Jon G. P. , Cross Tom E.
Published: October 2002

Two dielectric mixture equations were used in order to obtain estimates of theoretical permittivities from measurements on porous or powder ceramic specimens. Complex permittivities of alumina ( Al2O3) and zirconia ( ZrO2) were measured using a coaxial probe technique over the temperature and frequency ranges of 25-1200° C and 0.2-4.0 GHz, respectively. It appears that the equations are applicable to porous specimens but not always applicable to powder specimens without knowledge of density change and effect of porosity on permittivity change.
Sidewall-Less Depth Profiling with Auger Electron Spectroscopy
Authors: Inoue Kazuyuki , Tokoro Maki , Suzuki Noritomo , Matsubara Ryohji , Nakano Kenji
Published: October 2002

In Auger depth profiling in combination with ion sputtering, use of an insular sample has improved the depth resolution and has enabled pinpoint analysis without extending measurement time. An island capped with an erosion-resistant film remains on the substrate after chemical etching. When the island is prepared to be smaller than the area subjected to ion irradiation, no crater or its sidewall appears during depth profiling. It is demonstrated that in the determination of depth resolution, surface roughening owing to sputter deposition from the sidewall of a crater plays a key role, in addition to the interference by signals from a sidewall.
Spatial Frequency Doubling Method by Image Superimposition for Sub- 0.15-µm Optical Lithography
Authors: Otaka Akihiro , Kawai Yoshio , Tanaka Akinobu , Tadahito Matsuda Tadahito Matsuda
Published: October 2002

A new spatial frequency doubling method by image superimposition (FREDIS) is designed to improve the resolution limit up to the cutoff frequency. With FREDIS, the periodic image with half the pitch of the mask pattern is fabricated independently of the defocus and the pattern direction. It is based on flattening the 1st-order intensity distribution and extracting the 2nd-order intensity distribution whose frequency is twice that of the mask pattern. This is achieved by superimposing the images at two focal planes under coherent illumination. Experiments using KrF lithography with a conventional binary mask show FREDIS can be used to fabricate 0.14-µ m lines-and-spaces pattern with a large depth of focus of 2.0 µ m. In FREDIS, imaging characteristic is affected by some parameters such as the distance between two focal planes and the coherence factor of the illumination and show the effects of these parameters. We also discuss two techniques that help make this method more suitable for replicating actual device patterns. One enhances the contrast and the other corrects the image of the periphery of a periodic pattern.
Mask Defect Printability and Wafer Process Critical Dimension Control at 0.25 µm Design Rules
Authors: Yan Pei-yang , Langston Joe , Neff Julie , Chatterjee Ritwik
Published: October 2002

In this paper, the effect of mask defects in a wafer process is studied by taking into account the wafer process critical dimension ( CD) variability. We found that trade-offs between the wafer CD control specification, the actual wafer CD controllability, and the mask defect size requirement exist. We also developed a new statistical explanation for the printable mask defect size which is related to the wafer process specifications and the actual wafer process CD controllability. Based on our statistical assessment, any small mask defect is printable with a given failure rate. The advantages of our data analysis methods can be summarized as follows. 1. The printing effect for a given mask defect size can always be extrapolated even though that defect size is not present on the mask. The defect printability can be redefined without any additional data collection when the process control or the process specification is changed. 3. Information relative to data collection is maximized. 4. The defect printability risk analysis is tied to the process control and the process specifications.
Rough Polysilicon Film as a High-Performance Antireflective Layer for Sub-Half-Micron Photolithography
Authors: Dai Chang-Ming , Shun-Ho Liu Shun-Ho Liu
Published: October 2002

A rough polysilicon film (or hemispherical grain (HSG) film) was proposed for use as a high-performance antireflection layer for the sub-half-micron photolithographic process, especially for polysilicon gate patterning. This HSG film was inserted between WSix film and TEOS oxide film or deposited on top of TEOS oxide film. Elimination of notching and good critical dimension control were achieved in each case. This method is more straightforward and less complex than the organic bottom antireflection coating (ARC) process and could be easily implemented in integrated circuit manufacturing.
The SCattering with Angular Limitation in Projection Electron-Beam Lithography (SCALPEL) System
Authors: Liddle J. Alexander , Berger Steven D. , Biddick Chris J. , Blakey Myrtle I. , Bolan Keven J. , Bowler Stephen W. , Brady Kevin , Camarda Ron M. , Connelly Wayne F. , Crorken Andy , Custy Joe , Farrow Reggie C. , Felker Joe A. , Fetter Linus A. , Freeman Bob , Harriott Lloyd R. , Hopkins Leslie , Huggins Harold A. , Knurek Chester S. , Kraus Joe S. , Mixon Dave A. , Mkrtchyan Masis M. , Novembre Anthony E. , Peabody Milton L. , Simpson Wayne M. , Tarascon Regine G. , Wade Harry H. , Waskiewicz Warren K. , Watson G. Patrick , Williams Joe K. , David L. Windt David L. Windt
Published: October 2002

A SCALPEL\circledR (SCattering with Angular Limitation in Projection Electron-beam Lithography) proof-of-concept lithography system, comprising a tool, a reticle and a resist, has been designed to address the critical issues that must be investigated to determine if this approach is viable as a practical lithographic technology.
Effect of Overcoats in Chemically Amplified Resists against Water and Organic Bases
Authors: Nakamura Jiro , Ban Hiroshi , Kawai Yoshio , Akinobu Tanaka Akinobu Tanaka
Published: October 2002

We have evaluated poly-(acrylic acid) (PAA) and poly-(α-methyl-styrene) (PMST) as overcoats used to stabilize the lithographic performance of chemically amplified resist during the delay (PED) between exposure and post-exposure baking. We used water, aniline and NMP as model compounds of airborne contaminants. Both films are shown to improve the stability of resist performance during PED.
PMST is more effective in preventing atmospheric water penetration than PAA, as evidenced by the finding that the sensitivity of PAA-coated resist is dependent on the relative humidity of ambient air. Conversely, the PAA-coated resist is more stable against high vapor concentration of aniline and NMP, when exposed for several hours. This is probably because the negative charge of the carboxyl groups in PAA electrically traps aniline and NMP, preventing their penetration to the resist films.
Stress Control and Etching Study of W-Re as X-Ray Mask Absorber
Authors: Sugihara Shinji , Murooka Kenichi , Itoh Masamitsu , Higashikawa Iwao , Yoshio Gomei Yoshio Gomei
Published: October 2002

Stress control and etching of W-Re as X-ray mask absorber was studied. The W-Re film was deposited using an rf magnetron sputtering apparatus with two material targets. The substrates were revolved by themselves and over the W and Re targets to achieve uniform film thickness and stress. When the content ratio of W to Re was 1:1, non-columnar film structure was obtained. The stress repeatability, when the deposited film stress is near zero, was ±5×108 dyn/cm2. To further control the stress, implantation of Ar ions was carried out with an acceleration voltage of 180 kV.
The stress change was 1×109 dyn/cm2 compressive at the ion dose of about 6×1015 ions/cm2. The etching of W-Re was carried out using SF6 and CHF3 gas mixture and a Cr etching mask by applying magnetron reactive ion etching. The etching selectivity between W-Re and Cr was over 250 in the CHF3 content below 60%. We applied two-step etching to remove etch-obstructing films on the W-Re surface, and fabricated 0.1 µ m lines and spaces of 0.5-µ m-thick W-Re film.
X-Ray Projection Lithography Using a Fresnel Zone Plate
Authors: Koyama Naoe , Tsuyuzaki Haruo , Kuroda Kenichi , Akinori Shibayama Akinori Shibayama
Published: October 2002

In this article, we experimentally confirm the possibility of X-ray projection using a Fresnel zone plate (FZP) and monochromatic synchrotron radiation (SR) light at a wavelength of 10 Å by pattern replication. To evaluate the characteristics and patterning ability of the FZP, we designed one with a 4000-Å Ta absorber on a 0.2-µ m SiN membrane with a 0.159-µ m outermost zone width for 0.2-µ m resolution. Using the designed linear and circular FZPs, the focusing image of the X-ray source we obtained was almost equal to that predicted theoretically. We used FZP projection optics to obtain single-layer resist patterns as projection images. Moreover, using a penetrating mask, which is the conventional transmission type, We successfully replicated 0.2-µ m line and space and a mesh with a reduction ratio of 1/2.