bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezoelectric Properties of Fine-Grained Lead Zirconate Titanate Ceramics Modified with Pb(Sb1/2Nb1/2)O3
Authors: Tapaonoi Chanin , Shinjiro Tashiro Shinjiro Tashiro , Hideji Igarashi Hideji Igarashi
Published: October 2002

Sinterability, microstructure and piezoelectric properties were examined in the piezoelectric ceramics of the (1- x)Pb(Zr0.53Ti0.47)O3- xPb(Sb1/2Nb1/2)O3 ternary system. Pb(Sb1/2Nb1/2)O3 suppressed the grain growth of lead zirconate titanate (PZT) ceramics; the substitution with Pb(Sb1/2Nb1/2)O3 was effective to obtain fine-grained piezoelectric ceramics. Furthermore, the submicron grinding of calcined powder by ball-milling enabled densification even at the firing temperature of 1000° C. The piezoelectric ceramics having submicron-size grains were consequently obtained. The sample had an average grain size of 0.7 µ m and showed planar coupling factors (k
p) around 0.65.
Nonlinear Stress-Strain Behavior of PbZrO3–PbTiO3 under Various Temperatures
Authors: Tanimoto Toshio , Yamamoto Kohji , Tohru Morii Tohru Morii
Published: October 2002

This study deals with the tensile stress-strain behavior of piezoelectric ceramics under various environmental temperatures. The material used is commercial piezoelectric ceramics, PbZrO3–PbTiO3 (PZT). The tensile test was performed under various temperatures in the environmental chamber for poled and nonpoled samples having a specially designed specimen geometry, in order to discuss the effects of temperature on the stress-strain behavior. It was clarified that the stress-strain response of poled and nonpoled samples was nonlinear independent of test temperature, and the nonlinearity was stronger with the increase of test temperature. Moreover it was clarified that the stronger the nonlinearity is, the higher the fracture strength is.
Relationship between Poling Condition and Heat Resisting Properties in Lead Zirconate Titanate
Authors: Hirose Masakazu , Takada Mahoko , Hitoshi Oka Hitoshi Oka , Kazuo Miyabe Kazuo Miyabe
Published: October 2002

Poling conditions and heat resisting properties were discussed for lead zirconate titanate (PZT) ceramics. High poling (dc field applied from above Curie temperature to below Curie temperature on specimens) and normal poling (dc field applied from below Curie temperature) were applied as poling methods. As a result, high poling was found to give superior heat resisting properties to normal poling. Moreover, distinct domain structures were observed by microstructural analysis in the high poling sample, and it was found that these domain structures remained stable during heat testing. From these results, it was concluded that high poling resulted in a stable domain structure and consequently brought about superior heat resisting properties.
Piezoelectric and Dielectric Properties for Doped Lead Zirconate Titanate Ceramics under Strong Electric Field
Authors: Tani Takao , Watanabe Naoyoshi , Kazumasa Takatori Kazumasa Takatori , Saburo Hori Saburo Hori
Published: October 2002

Piezoelectric and dielectric responses were investigated for doped lead zirconate titanate (PZT) ceramics under strong electric field (1.6 MV/m). Displacements and polarization changes were measured and the effects of dopants were discussed. Doping of 2% Nb significantly increased the displacement of (Pb0.875Sr0.125)(Zr0.55Ti0.45)O3 ceramics. Doping of 2% Fe suppressed 90° domain rotation and decreased displacement. Results were discussed by dividing displacement and polarization change into two components, i.e., a piezoelectric or dielectric contribution and a 90° domain rotation contribution.
Piezoelectric Properties of Solid-Solution (Bi1-x(PbBa)x)(Ni(1-x)/2Ti(1+x)/2)O3Ceramics
Authors: Okuda Takeo , Masatoshi Yamada Masatoshi Yamada , Tadashi Takenaka Tadashi Takenaka
Published: October 2002

The dielectric, ferroelectric, piezoelectric and mechanical properties of a new solid solution, (1-x)·Bi(Ni0.5Ti0.5)O3-x·(PbaBab)TiO3(a+b=1) ( NTPB[100x-100a/100b]), as a new group of piezoelectric ceramics, are studied. NTPB[0-100a/100b] (BINT) is a mixture of a bismuth layered structure consisting of Bi4Ti3O12, NiO and Bi2O3. Whenxis increased, the crystal structure changes from a mixture of bismuth layered and perovskite structures to a single phase of the perovskite structure at aboutx=0.2, being independent of the ratio of PbTiO3(PT) to BaTiO3(BT). The electromechanical coupling factorsk33,ktandkPof NTPB[40-100/0]+Mn(0.02 wt%) are about 51%, 47% and 32%, respectively. The mechanical bending strength of NTPB[44.5-100/0]+Mn(0.02 wt%) is about 150 MPa.
Piezoelectric Vibratory Gyro-Sensor Using a Trident-Type Tuning Fork Resonator
Authors: Akira Satoh Akira Satoh , Yoshiro Tomikawa Yoshiro Tomikawa , Kazumasa Ohnishi Kazumasa Ohnishi
Published: October 2002

This paper deals with a piezoelectric vibratory gyro-sensor using a trident-type tuning fork resonator. It is expected that the vibratory gyro-sensor has a high stability as an angular rate sensor. In order to develop such a gyro-sensor, the authors have focused on applying a trident-type tuning fork resonator that is independent of its support condition. In this paper, the vibrational analysis of a trident-type tuning fork resonator and its measured characteristics as an angular rate sensor are described.
Analysis of Sensitivity of Accelerometer Using Multilayer Piezoelectric Ceramics
Authors: Sato Ken , Okamoto Kohichi , Yoshiaki Fuda Yoshiaki Fuda , Tetsuo Yoshida Tetsuo Yoshida
Published: October 2002

We have investigated the application multilayer piezoelectric ceramics (MPC) to accelerometers to sense acceleration in the low-frequency range. A method of analysis applying the piesoelectric fundamental equation of bimorph to each layer of the MPC and summing them up has been studied. The propriety of this method was demonstrated by comparing calculated and experimental results.
Transducer Performance for Leaky Wave in Layered Structure of Piezoelectric Ceramic Thin Plate and Acryl Plate
Authors: Kohji Toda Kohji Toda , Yasuhiko Akutsu Yasuhiko Akutsu
Published: October 2002

A leaky wave transducer in the combination of a piezoelectric ceramic thin plate and an acryl plate is described, which functions as a transducer for underwater ultrasound. The operation performance of an interdigital transducer in the layered structure is described from the viewpoint of phase velocity, electromechanical coupling constant, mode conversion efficiency and transducer efficiency. The leaky wave transducer has multiple modes with velocity dispersion. Using the second-order anti-symmetrical mode with high transducer efficiency value, a liquid-delay line oscillation is demonstrated.
Dielectric Properties of Rare-Earth-Oxide-Doped BaTiO3 Ceramics Fired in Reducing Atmosphere
Authors: Okino Yoshikazu , Shizuno Hisamitsu , Shinya Kusumi Shinya Kusumi , Hiroshi Kishi Hiroshi Kishi
Published: October 2002

In order to gain an understanding of highly reliable electrical characteristics for the Ho-doped multilayer ceramic capacitors with Ni electrodes, dielectric properties of various rare-earth-oxide-doped BaTiO3 ceramics were studied. The smaller ionic radius rare-earth-oxide (Dy, Ho, Er)-doped samples showed lower resistivity in reducing atmosphere, but higher resistivity in oxidizing atmosphere at the cooling stage, compared with the larger-ion (La, Sm, Gd)-doped samples. Multilayer ceramic capacitors with Ni electrodes using the smaller-ion-doped materials showed smaller aging rate and longer lifetime. We developed Ni-electrode MLCs with X7R specification as 1 µ F in the 2125 type.
Si LSI Process Technology for Integrating Ferroelectric Capacitors
Authors: Arita Koji , Fujii Eiji , Shimada Yasuhiro , Uemoto Yasuhiro , Nasu Toru , Inoue Atsuo , Matsuda Akihiro , Suzuoka Tatsuo Otsuki
Published: October 2002

The fabrication procedure of ferroelectric thin film capacitors onto conventional Si LSIs is investigated. Electrical characteristics of the integrated Ba1-
x

Sr

x

TiO3 (BST) capacitors and the metal-oxide-semiconductor transistors embedded in the Si substrate are examined. Results of these measurements suggest the usefulness of this integration process for the fabrication of ferroelectric thin film devices, which is substantiated by the evaluation of an analog/digital IC with the integrated BST bypass capacitor.
Pyroelectric IR Detectors Using Periodic Inverted Domains of LiTaO3
Authors: Kiyoshi Nakamura Kiyoshi Nakamura , Moto Itagaki Moto Itagaki
Published: October 2002

In this paper, a new-structure pyroelectric infrared detector is proposed, which consists of interdigital electrodes deposited on periodic inverted domains of ferroelectric crystal. Since only a shallow region close to the crystal surface is pyroelectrically active in this structure, the surface charges are quickly induced in response to IR irradiation and this structure therefore provides us with a high responsivity. A pyroelectric detector fabricated using periodic antipolar domains formed by selective proton exchange and subsequent heat treatment of LiTaO3 crystal is experimentally demonstrated to exhibit a high current responsivity in high frequency range of IR power modulation.
Synthesis and Properties of (1-x)PZN-xBZN Solid-Solution Compounds by Liquid-Evaporation Method
Authors: Kang Sang-goo , Kim Hwan , Koichiro Takahashi Koichiro Takahashi , Masayuki Tsukioka Masayuki Tsukioka
Published: October 2002

Solid-solution compounds of (1- x)PZN- xBZN were synthesized by a spray-drying method, which is one of the liquid-evaporation methods. The morphology and size of metal nitrate powders could be changed by processing by the spray-drying method. More than 10 mol% BZN was needed to stabilize the 100% perovskite phase with the method. Lattice parameters of perovskite structure increased with the amount of Ba substitution. Comparing the liquid-evaporation method and the solid-state reaction method, the reaction rate is faster and the dielectric constants of sintered samples are higher in the liquid-evaporation method. Maximum dielectric constants at room temperature showed a value of about 9200 which was about 2000 higher than in the conventional solid-state reaction method, and a dissipation factor of 2–4% at room temperature was observed.
Initial Stage of Growth Process of Lead Titanate Fine Particles
Authors: Ishikawa Kenji , Okada Nagaya , Takada Kazumasa , Nomura Takashi , Toyoda Minoru Hagino
Published: October 2002

A study on the initial growth stage of lead titanate fine particles with nanometer size is described in this paper. A mixture of the constituent metal alkoxides was hydrolyzed to obtain amorphouslike particles of lead titanate around 5 nm in diameter. The hydrolysate was calcined to crystallize in atmosphere at various temperatures. The volume of the particle increased in proportion to the duration of the calcination. This time dependence is explained by assuming that coalescence occurs at limited areas of the particles such as corners or kinks. The size of as-prepared fine particles was uniform but their distribution became varied as the average size was increased by calcination.
Preparation and Properties of Pb[(Sc1/2Nb1/2)0.575Ti0.425]O3 Ceramics
Authors: Adachi Masatoshi , Emi Miyabukuro Emi Miyabukuro , Akira Kawabata Akira Kawabata
Published: October 2002

Pb[(Sc1/2Nb1/2)0.575Ti0.425]O3 (PSNT) was prepared by the two-step calcining method. The sintering conditions for PSNT ceramics were investigated in the temperature range of 1200 to 1300° C. The density of PSNT fired at 1300° C was 7.5 g/cm3, which was in the range of 93% of the theoretical value. The dielectric constant and tan
δ were 1760 and 0.022, respectively. The pyroelectric coefficient of this ceramic sample was 50 nC/cm2 K, which is larger compared with other well-known pyroelectric materials. The spontaneous polarization P
s calculated by the pyroelectric current method showed a typical diffuse phase transition and its value was 28 µ C/cm2 at room temperature. Large coupling factors of k
p=51 % and k
t=53 % were obtained.
Dielectric Properties of Solid Solutions (1-x)Pb(In1/2Nb1/2)O3-xPbZrO3
Authors: Naohiko Yasuda Naohiko Yasuda , Takuya Mizuno Takuya Mizuno
Published: October 2002

Dielectric properties of (1- x)Pb(In1/2Nb1/2)O3 (PIN)- xPbZrO3 (PZ) were investigated. For PZ concentrations x<0.3, diffuse phase transition was observed. With increasing x, maximum permittivity ε
′
rm increased, and the temperature T
m at which ε
′
rm appeared shifted towards higher temperatures. For x>0.3, ε
r
′ had a sharp peak at T
c. With increasing x, the peak value decreased and T
c shifted toward higher temperatures. The phase below T
c was confirmed to be ferroelectric by observation of P-E hysteresis loops. The phase transformation from the relaxor to ferroelectric state occurred at x=0.3. For x>0.8, a steplike anomaly appeared at T
t below T
c. With increasing x, this anomaly became larger, and T
t shifted toward higher temperatures. The phase below T
t was confirmed to be antiferroelectric by observation of P-E double hysteresis loops. There was a structural change characterized by the splitting of the structure-sensitive maximum of (200) reflection of XRD patterns, similar to orthorhomic PZ, around x=0.8. Two morphotropic phase boundaries were found; one between pseudocubic and rhombohedral phases with ε
′
rm of 12000 at 100 kHz was at x=0.3, and the other between rhombohedral and orthorhombic phases was at x=0.8 at room temperature.
Effect of Firing Atmosphere on Electrical Properties of Multilayer Semiconducting Ceramics Having Positive Temperature Coefficient of Resistivity and Ni–Pd Internal Electrodes
Authors: Kanda Atsushi , Shinjiro Tashiro Shinjiro Tashiro , Hideji Igarashi Hideji Igarashi
Published: October 2002

Multilayer semiconducting (Ba, Ca)TiO3 ceramics having positive temperature coefficient of resistivity (PTCR) were fired in reducing-reoxidizing atmospheres using Ni–Pd alloys as internal electrodes. Nickel was added to palladium electrodes to form the ohmic contact between internal electrodes and ceramics. Samples were fired at 1350° C for 2 h in reducing atmospheres composed of H2 and N2 gases, and then were annealed for 2 h in reoxidizing atmospheres composed of O2 and N2 gases in the cooling process. The effects of firing atmosphere on voltage-current and PTCR characteristics were experimentally investigated.
Optical Activity and Phase Transition of Pb1-xLax(ZryTiz)1-x/4O3
Authors: Yoshii Hiroshige , Shimasaki Tsuyoshi , Ichiki Masaaki , Itagaki Yosuke , Asahi Toru , Saito Kazuya , Kobayashi Jinzo , Ikawa Hiroyuki
Published: October 2002

Electric field dependences of optical activity and birefringence of Pb0.92La0.08(Zr0.7Ti0.3)0.98O3(PLZT(8/70/30)) were studied using the high-accuracy universal polarimeter (HAUP) method in a temperature region between 0° C and 90° C. PLZT(8/70/30) was optically active in the low-temperature and inactive in the high-temperature phases. Furthermore it was revealed that gyration and birefringence in the low-temperature phase manifested typical butterfly hysteresis loops with respect to electric fields. From analysis of Weissenberg photographs, the ceramics of both high- and low-temperature phases were found to consist of crystallites which were distributed in equal weight along the total solid angles. Using the combined evidence from HAUP and X-ray methods, it was clarified that the classes of the high- and low-temperature phases are T
h and C3, respectively.
Photorefractive Effect in Bi4Ge3O12
Authors: Osamu Kamada Osamu Kamada
Published: October 2002

The photorefractive effect in Bi4Ge3O12 and its incident laser power and temperature dependence are studied. From these measurements, a very small photoinduced refractive index change, Δn=1.2×10-6 (E
a=2.5 kV/cm, I=97 mW/cm2), is observed. The response times (the rise time and the decay time) show the sublinear intensity dependence as well as the photocurrent. The rise time and the decay time under illumination are in the range of 10–100 s. The decay time data are analyzed as double exponential curves, suggesting two types of charge-carrier dynamics contributions to the photorefractive effect.
Anomalous Behavior of Spontaneous Polarization in Ferroelectric Liquid Crystal Mixture
Authors: Fuwa Yoshiaki , Myojin Katsunori , Moritake Hiroshi , Ozaki Masanori , Yoshino Katsumi , Tani Takeshi , Fujisawa Koichi
Published: October 2002

Anomalous behaviors of spontaneous polarization in a binary mixture of the chiral smectic and non-chiral smectic liquid crystals have been found. The spontaneous polarization P
s of the ferroelectric liquid crystal possessing high P
s decreases drastically upon doping with non-chiral smectic C liquid crystal. The sign inversion of P
s is observed in a mixture highly doped with non-chiral liquid crystal.
Unidirectional Layer Alignment in Ferroelectric Liquid Crystal with N*-C* Phase Sequence
Authors: Myojin Katsunori , Moritake Hiroshi , Ozaki Masanori , Yoshino Katsumi , Tani Takeshi , Fujisawa Koichi
Published: October 2002

Alignment of the smectic layer in ferroelectric liquid crystal which has a chiral nematic ( N*)-chiral smectic C (SmC*) phase sequence has been studied. The large-area monodomain has been realized by an ac field treatment. In this alignment, the layer normal is parallel to the rubbing axes even in a cell in which both the surfaces are rubbed.
Concise Analytical Model for Deep Submicron N-Channel Metal-Oxide-Semiconductor Devices with Consideration of Energy Transport
Authors: Shyh-Yih Ma Shyh-Yih Ma , James B. Kuo James B. Kuo
Published: October 2002

This paper reports a concise analytical model for deep submicron n-channel metal-oxide-semiconductor (NMOS) devices taking energy transport into consideration. It was verified that the I-V characteristics obtained using the analytical model agree with those obtained experimentally.
Determination of the Frequency Dependence of Complex Permittivity in the Pseudo-Microwave Range by an Advanced Perturbation Method
Authors: Takahashi Takeshi , Iijima Yasushi , Makoto Kobayashi Makoto Kobayashi , Taro Miura Taro Miura
Published: October 2002

The authors proposed a suitable technique for the evaluation of complex permittivity in the pseudo-microwave range. Considerable improvements have been made in the accuracy of Q evaluation by the cavity perturbation method. The advanced method employed was five times as accurate as the conventional cursor function method, installed in network analyzers. The frequency dependence of complex permittivity for microwave dielectrics and low-temperature-fireable materials was also discussed. The results of frequency dependence measurements demonstrated that some characteristics of microwave dielectrics could not simply be determined by the Q
f-constant rule. Therefore, development of an evaluation technique within the confines of the pseudo-microwave range was significant.
Preparation and Properties of Ceramics Prepared from Bi4Ti3O12 Amorphous Material
Authors: Kazuo Shoji Kazuo Shoji , Yasuo Uehara Yasuo Uehara
Published: October 2002

We attempted to prepare a low-temperature-fired Bi4Ti3O12 ceramics from an amorphous substance as a basic material and Bi2O3 as a liquid phase material. When Bi2O3 was added in the amount of 10% by weight to the basic material, and then the mixture was fired under the conditions of 870° C–5 h, ceramic samples having a relative density of about 90% were prepared. The grain sizes of the sample were 2 µ m or less, that is, about one-tenth that of a sample fired under standard conditions. The electric properties of the samples were also examined. Results showed that the electrostatic capacitance change (ΔC/C) of the sample caused by the DC bias was relatively low. The DC dielectric breakdown strength was 1.4 times higher, and the remanent polarization was about one-third, as compared with a sample fired under standard conditions.
Crystallizing Process of Amorphous Thick Films of Ferroelectric Lead Germanate Family
Authors: Jun Hatano Jun Hatano , Tomonori Mukaigawa Tomonori Mukaigawa , Hiroyuki Uehara Hiroyuki Uehara , Alexei Gruverman Alexei Gruverman , Koichiro Takahashi Koichiro Takahashi , Ken Yukino Ken Yukino
Published: October 2002

Real-time investigation of crystallizing processes of amorphous thick films of ferroelectric lead germanate (PGO) and silicon-doped PGO (PGSO) is carried out using a high-temperature X-ray diffraction system. Two irreversible phase transitions took place near 370° C and 530° C on heating: the first is the crystallization from the amorphous to a metastable crystal state, and the second is from the metastable to a ferroelectric stable state of Pb5Ge3O11. Both transitions were completed very quickly, i.e., within approximately 7 and 58 min, respectively. The optimum heat-treatment conditions for fabricating well-oriented polycrystalline films were discussed together with the results of quick heating and quenching experiments.
Growth of 3-Inch-Diameter Li2B4O7 Single Crystal Using the Resistance Heating Furnace
Authors: Sugawara Tamotsu , Ryuichi Komatsu Ryuichi Komatsu , Tadashi Sugihara Tadashi Sugihara
Published: October 2002

The mode and origin of cracking of lithium tetraborate ( Li2B4O7) single crystals during growth using a resistance heating furnace have been studied. The relationship between the formation mechanism of anomalous growth ridges and the occurrence of cracking was examined. It is concluded that a high temperature gradient near the interface and small temperature fluctuations in the melt are needed for growing a crack-free 3-inch-diameter Li2B4O7 single crystal.
Ferroelectric Properties and Fatigue Characteristics of Bi4Ti3O12 Thin Films by Sol-Gel Processing
Authors: Toyoda Masahiro , Hamaji Yukio , Payne Kunisaburo Tomono
Published: October 2002

Stoichiometric Bi4Ti3O12 thin films were prepared by sol-gel processing. This paper discusses the synthesis of polymerizable solutions containing Bi and Ti, ferroelectric properties and fatigue characteristics of the resulting Bi4Ti3O12 thin films. The complex alkoxide was prepared by allowing Bi acetate to react with Ti alkoxides. Bismuth acetate and titanium methoxyethoxide, the solvents 2-methoxyethanol and glacial acetic acid were selected based on their successful use in a number of related systems. Thin films of Bi4Ti3O12 were obtained onto platinized Si substrates by spin casting, followed by heat treated at 700° C. The value of the dielectric constant and loss at 400 Hz, 100 mVrms, 25° C of this virgin films were 132 and 0.8%, respectively. This thin films with single phase layerd perovskite-like structure had very good D-E hysteresis characteristics. The remnant polarization, P
r, and coercive field, E
c, of this virgin films were 5.5 µ C/cm2 and 6.2 kV/cm, respectively. The remnant polarization of this thin films, P
r
+, P
r
-, and 2P
r, were nearly constant up to 108 cycles. At 4×108 cycles, the decay in remnant polarization, P
r
+, P
r
-, and 2P
r, was observed to be about 35% of the initial values, respectively. The coercive field was drastically increased after 108 cycles. The D-E hysteresis loop after 108 cycles was not completely saturated. After 108 cycles, leakage current was typically increased. We considered that the fatigue characteristics observed in our study are resulted from increasing of leakage current.
Variation of Dielectric Constant Affected by Domain Structure and Electric-Field-Induced Strain in Ferroelectric Ceramics
Authors: Yoichiro Masuda Yoichiro Masuda
Published: October 2002

The dc electric bias and frequency dependence of the dielectric constants for lead zirconate titanate (PZT) ceramics with ferroelectric phase were measured at room temperature for several frequencies from 1 kHz to 1 MHz. The variation of dielectric constants versus biasing field and frequency was explained by introducing 180° and 90° domains. The actual strain measurement of ceramics was performed by a potentiometer. Assuming that the strain was caused by piezostriction and electrostriction, the piezostriction and electrostriction coefficients were determined by the least squares method, and the spontaneous strain induced by an internal electric field was discussed.
Acoustic Emission and Domain Switching in Tetragonal Lead Zirconate Titanate Ceramics
Authors: Yasuyoshi Saito Yasuyoshi Saito , Saburo Hori Saburo Hori
Published: October 2002

The electric field-induced acoustic emission (AE) in a poled tetragonal lead zirconate titanate (PZT) ceramic was measured at room temperature and related to the polarization switching, field-induced strain, dielectric constant, and piezoelectric constant in the high-voltage electric field. The AE signals became most remarkable when the polarization approached the saturation, while they became minimal when the polarization reversal occurred. The AE count, expressed as a function of electric field, exhibited a hysteresis loop similar to the strain loop. These data suggest that the AE signals were generated by the strain due to 90° domain switching rather than the piezoelectric strain.
Raman Scattering Study of Bismuth Layer-Structure Ferroelectrics
Authors: Kojima Seiji , Imaizumi Ryo , Hamazaki Shinichi , Takashige Masaaki
Published: October 2002

The lattice dynamical properties have been studied by Raman spectroscopy in bismuth layer-structure oxides Bi4Ti3O12, and ABi4Ti4O15(A=Ba, Ca, Pb, Sr). The rigid-layer modes were observed in all compounds in the range 57–62.5 cm-1. The lowest mode of Bi4Ti3O12shows marked softening, and the square frequency of the lowest mode is linearly related to the square of the spontaneous polarization. As for CaBi4Ti4O15and SrBi4Ti4O15the underdamped soft modes were also clearly observed. In contrast, in BaBi4Ti4O15only low-frequency overdamped modes have been observed. In PbBi4Ti4O15the low-frequency spectra have a complicated structure and the softening of the underdamped modes was not observed clearly.
Phonon Hole Burning in Piezoelectric Powder of KH2PO4 and SiO2
Authors: Fujio Tsuruoka Fujio Tsuruoka
Published: October 2002

Phonon hole burning phenomena were observed in two kinds of powder, KH2PO4 and SiO2. The mechanism of hole formation was investigated. Through measurement of the electrical impedance of a parallel-plate capacitor filled with KDP powder, it was revealed that a hole was produced with increase of oscillation damping. In the SiO2 sample, decrease of the damping constant was observed by measurements of the decay time of free oscillation. Holes were represented by the change of the characteristics of oscillation. Obtained results were explained as the contribution of vibrating dislocations in the particles.
Charge Storage on Thin SrTiO3 Film by Contact Electrification
Authors: Uchihashi Takayuki , Okusako Takahiro , Tsuyuguchi Takeshi , Sugawara Yasuhiro , Igarashi Masaru , Kaneko Reizo , Seizo Morita Seizo Morita
Published: October 2002

Charge storage on thin SrTiO3 (STO) film was investigated by contact electrification. An atomic force microscope (AFM) biased by the voltage was used to deposit the charges by contact electrification and to detect electrostatic force change induced by contact electrified charges. As a result, writing, reading and erasing were demonstrated successfully with a small pattern, small letters and small dot arrays. Besides, two adjacent positive charge dots were discriminated with separation as small as ∼63 nm. These results revealed the potential capability of the present system, i.e., contact electrification on STO film with a biased AFM, for high-density charge storage.
Defects in Czochralski-Grown Silicon Crystals Investigated by Positron Annihilation
Authors: Ikari Atsushi , Kawakami Kazuto , Haga Hiroyo , Uedono Akira , Wei Long , Kawano Takao , Tanigawa Shoichiro
Published: October 2002

Positron lifetime and Doppler broadening experiments were performed on Czochralski-grown silicon crystals. A monoenergetic positron beam was also used to measure the diffusion length of positrons in the wafer. From the measurements, it was observed that the value of diffusion length of positrons decreased at the region where micro-defects were formed during the crystal growth process. It was also found that the line shape parameterSdecreased and the lifetime of positrons increased at the region. These results can be attributed to the annihilation of positrons trapped by vacancy oxygen complexes which are formed in association with the microdefects.
Chemical Treatment Effect of Si(111) Surfaces in NH4F Solution Studied by Spectroscopic Ellipsometry
Authors: Takahiro Suzuki Takahiro Suzuki , Sadao Adachi Sadao Adachi
Published: October 2002

Chemically treated Si(111) surfaces in NH4F (40%) solution at 20° C
have been studied using spectroscopic ellipsometry (SE) and exsitu atomic force
microscopy (AFM). The SE data clearly indicate that the solution causes
the removal of the native oxide with an etch rate of ∼ 15 Å/min. Just
after the native oxide is etched away completely (t∼ 70 s), the SE data yield
the spectrum of a slightly roughened surface. With further etching, the Si surface
becomes gradually rougher. The roughened surface thickness immersed for t∼ 600 s,
for example, is ∼ 16.5 Å with a void fraction of ∼ 42%, obtained
using an effective medium approximation (EMA); the resulting AFM image of this sample
indicates a roughened surface of ∼ 14 Å rms with the emergence of pillars and
hollows. It can thus be concluded that SE can be used to assess important chemical treatment parameters of crystalline Si.
Damage Formed by Plasma Boron Doping in Silicon
Authors: Hara Tohru , Nakamura Kiyotaka Shinada
Published: October 2002

Damage formed by DC plasma doping of boron to silicon is studied. Damage density is
measured by 1.5 MeV He+ Rutherford backscattering spectrometry and photoacoustic
displacement techniques. These damage density measurements show that lower-damage doping
can be achieved in plasma doping compared with that of ion implantation. Impurity diffusion
does not occur as rapidly in this doping as seen in B+ and BF2
+
implantations. The diffusion coefficient of boron is as low as 4.9× 10-15 cm2/s at 950° C
in this doping. This coefficient is 5 and 40 times lower than that of B+ and
BF2
+ implantations, respectively. Correlation of the diffusion coefficient
with damage density is found. A shallow and high peak carrier concentration p+ layer can be formed by plasma boron doping.
Incorporation Process of the As Atom on the InP(001) Surface Studied by Extended X-Ray Absorption Fine Structure
Authors: Shioda Ryu , Oyanagi Hiroyuki , Kuwahara Yuji , Takeda Yoshikazu , Haga Koukichi , Kamei Hidenori
Published: October 2002

The incorporation process of As atoms during metalorganic vapor phase epitaxy
(MOVPE) has been studied by extended X-ray absorption fine structure (EXAFS). The growth
of InP(001) was interrupted and the surface was exposed to arsine ( AsH3)
for the investigation of the incorporation of As atoms during the AsH3 gas
flow interval. It was found that the As atoms replace the P atoms, from the analysis
of the As K-edge EXAFS. The amount of the incorporated As atoms as a function of the
AsH3 exposure time shows that the substitution consists of two processes with
different time scales. In the fast process, which saturates in a few seconds, the
incorporated As atoms substitute the P atoms on the surface with an anomalous bond
length relaxation, while the slow process continues in the subsurface over a wide rage of the exposure time.
Bond Length Relaxation in Ultrathin InAs and InP0.4As0.6 Layers on InP(001)
Authors: Kuwahara Yuji , Oyanagi Hiroyuki , Shioda Ryu , Takeda Yoshikazu , Yamaguchi Hirotaka , Masakazu Aono Masakazu Aono
Published: October 2002

Bond length relaxation in InAs and InP0.4As0.6 ultrathin layers on
InP(001) substrates has been studied by the extended X-ray absorption fine structure
using synchrotron radiation. The In–As bond lengths have been determined as a function
of film thickness from 1000 Å to 3 Å. In ultrathin film, the In–As bond
lengths in both InAs and InP0.4As0.6 alloys are shorter than the bulk value
by the epitaxy-induced strain due to the lattice mismatch. It was found that on increasing
the film thickness, the In–As bond lengths gradually approach the values in the bulk
material. The relative variation of bond length is not dependent on the magnitude of
lattice spacing, which suggests that the mechanism of relaxation is ascribed to the
local strain (bond length mismatch) rather than the macroscopic average.
Selenium Doping in GaAs Grown by Molecular Beam Epitaxy
Authors: Eriko T. Sano Eriko T. Sano , Yoshiji Horikoshi Yoshiji Horikoshi
Published: October 2002

Using elementary Se as n-type dopant,
Se-doped GaAs films were grown by molecular beam epitaxy.
Characteristics of the films can be classified
according to the amount of Se doped into areas where
carrier concentration
increases linearly [area I]
(Se concentration ≤4 ×1018 cm-3),
saturates [area II] ( 4 ×1018–1 ×1020 cm-3)
and decreases [area III] ( ≥1 ×1020 cm-3).
In each area, we found a close correlation between
electrical activity and photoluminescence spectra.
The activation ratio of Se donors was found to be high
in the samples classified in area I.
These samples showed an efficient photoluminescence,
although the observed spectra included deep level emissions
at 890 nm and 1050 nm in addition to the band-edge
excitonic emission.
For the samples in areas II and III, however,
photoluminescence efficiency dropped considerably
and only a broad band emission (1300–1500 nm)
appeared.
This broad band emission is probably caused by
complexes that include Ga
vacancies and Se atoms because
distinct electron concentration saturation takes place
in this region.
High-Field Electron Transport and Hot Electron Phenomena in Hydrogenated Amorphous Silicon Films
Authors: Nakata Jun-ichi , Nakajima Shigeki , Inuishi Shozo Imao
Published: October 2002

Electron transport under high electric field in hydrogenated amorphous silicon
(a-Si:H) films has been investigated by means of time-of-flight (TOF) measurements.
The drift mobility µ increased with increasing applied electric field E accompanied
by a simultaneous increase in the dispersion parameter α resulting in nondispersive
transport. The electron thermal runaway breakdown field E
* with optical carrier
injection decreased with increasing ambient temperature T
a in accordance with the
hot electron theory in amorphous solids [H. Fröhlich: Proc. R. Soc. London A 118 (1947) 521].
The field dependencies of µ and α are also explained by taking account of
the increase in the effective electron temperature (hot electron phenomenon) at high
field in the theory of dispersive transport.
Analysis of Joule Heat in a-Si:H Film by Photothermal Deflection Spectroscopy
Authors: Ikurou Umezu Ikurou Umezu , Keiji Maeda Keiji Maeda
Published: October 2002

Photothermal deflection (PD) signals without applied bias are a direct observation of nonradiative recombination processes of photoexcited carriers, which strongly correlate with photocurrent under applied bias.
The PD signal under DC bias was carefully compared with the photocurrent (PC) signal in the energy region around and above the band gap.
A large dip, which was not observed in PC spectra, was observed in PD spectra in the spectral region near the absorption edge.
This spectral feature was discussed from the standpoint of Joule heat due to drift of photocarriers. We have pointed out that dark Joule heat (W
d) and effective applied voltage (V
S) are important in analysis.
By taking into account these parameters, the experimental spectrum of PD signals under DC bias was successfully reproduced.
It is concluded that variation of V
S which arises from large photosensitivity causes a dip in PD spectra. No evidence of the photon energy dependence of the recombination process was observed in PD spectra.
Low-Hydrogen-Content, Stable Amorphous Silicon Thin Films Prepared by Ion-Assisted Method
Authors: De Subal Chandra , Tarui Hisaki , Terakawa Akira , Maruyama Eiji , Sayama Katsunobu , Ninomiya Kunimoto , Shinya Tsuda Shinya Tsuda , Shoichi Nakano Shoichi Nakano
Published: October 2002

Low-hydrogen (H)-content (≤10%) amorphous silicon (a-Si) films have been
prepared by the hydrogen ion- and atom-assisted ionized cluster-based deposition method.
In this technique, hydrogen content can be controlled independently and the optical gap
(E
opt3) of 1.5 to 1.15 eV can be obtained within an acceptable range of
substrate temperature (180 to 230° C). The variation of optoelectronic
properties with process parameters has been discussed. The stability against light
exposure of these low-H-content films has been verified. The films are not susceptible
to light exposure; however, for higher H content, film properties degrade, albeit
slightly. The degradation behavior has been compared with that of a hydrogenated
amorphous silicon germanium (a-SiGe:H) film with the same E
opt3 (1.31 eV)
and the superiority of low-H-content a-Si with regard to stability was indicated.
Comprehensive Study of Lateral Grain Growth in Poly-Si Films by Excimer Laser Annealing and Its Application to Thin Film Transistors
Authors: Kuriyama Hiroyuki , Nohda Tomoyuki , Aya Yoichirou , Kuwahara Takashi , Wakisaka Kenichiro , Kiyama Seiichi , Tsuda Shinya
Published: October 2002

Lateral grain growth in nondoped poly-Si films was studied by using Si thin films
(500 Å) with different structures as a starting material for excimer laser crystallization.
It was clarified that the lateral grain growth phenomenon (micron-size grains with strong
(111) orientation) upon excimer laser annealing was strongly affected by both the
microstructure and the orientation of the initial Si thin films. This result supports
our previous speculation that the principal driving force of the lateral grain growth
phenomenon is surface energy anisotropy. Poly-Si thin-film transistors using these
films show a high field effect mobility of 440 cm2/V·s, achieved through
a low-temperature process below 600° C. This excellent electrical characteristic
is thought to be due to the large grain size of poly-Si thin film with controlled
orientation, good crystallinity, and a smooth surface.
Substrate Temperature Dependence of Deuteron Bonding States in Deuterated Amorphous Silicon Studied by 2H Nuclear Magnetic Resonance
Authors: Hayashi Shigenobu , Yamasaki Satoshi , Matsuda Akihisa
Published: October 2002

2H nuclear magnetic resonance (NMR) spectra have been measured for deuterated
amorphous silicon deposited at substrate temperatures from ambient to 400° C.
Concentrations of four kinds of deuteron bonding states are determined; SiD and SiD2
in a rigid state, SiD3 in a freely rotating state, D2 molecules in a freely mobile state, and
SiD

n

(n=1, 2, and 3) with bond angle distortions in a constrained mobile state.
The former three decrease with the substrate temperature, while the last increases.
Highly Polarized Electron Source Using InGaAs–GaAs Strained-Layer Superlattice
Authors: Omori Tsunehiko , Kurihara Yoshimasa , Takeuchi Yasunori , Yoshioka Masakazu , Nakanishi Tsutomu , Okumi Shoji , Tsubata Mitsuru , Tawada Masafumi , Togawa Kazuaki , Tanimoto Yasunori , Takahashi Chikako , Baba Toshio , Mizuta Masashi
Published: October 2002

We have studied the polarization of photoemission from an In0.15Ga0.85As–GaAs
strained-layer superlattice. The polarization of 82.7±0.3(stat.)±6.1(syst.)%
was observed at laser wavelengths from 911 to 916 nm at room temperature. The quantum
efficiency at the wavelength of 911 nm was ∼0.015% in the vacuum of ∼6×10-10 Torr with high cathode voltage of -4 kV.
Wafer Treatment Using Electrolysis-Ionized Water
Authors: Aoki Hidemitsu , Nakamori Masaharu , Nahomi Aoto Nahomi Aoto , Eiji Ikawa Eiji Ikawa
Published: October 2002

Electrolysis-ionized water treatment is shown to be useful for removing polystyrene
particles from contact holes, silicon surface cleaning and the removal of metal contamination
such as copper. Electrolysis-ionized water
has a controllable pH and a higher oxidation-reduction potential than chemicals. Moreover, this water does not
contain acid or alkaline chemicals, and can easily be neutralized without adding chemicals.
Electrolysis-ionized water treatment has great potential for ecologically safe and low cost semiconductor processing.
Confirmation of Aluminum Distribution in Thermally Grown Oxide of Silicon Wafers
Authors: Shimizu Hirofumi , Uchida Hiroshi , Shuichi Ishiwari Shuichi Ishiwari
Published: October 2002

The concentration depth profile of aluminum (Al) in the thermally-grown silicon (Si) dioxide ( SiO2) is investigated in detail using high resolution inductively coupled plasma mass spectroscopy. A conceptual model is proposed where the Al segregated at the very top of the SiO2creates a negative charge layer by forming an (AlOSi)-network, and a small amount of Al residing in the SiO2–Si interface gives some possibilities of forming interface traps. This interpretation is based on the results reported here and on previous results obtained from ac surface photovoltage measurements.
Transport Critical Current Densities in Uniaxially and Biaxially Oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9Superconducting Films on Ag and SrTiO3Substrates Prepared by a Spray Pyrolysis Method
Authors: Doi Toshiya J. , Yuasa Toyotaka , Takeshi Ozawa Takeshi Ozawa , Kazutoshi Higashiyama Kazutoshi Higashiyama
Published: October 2002

Tl1(Ba0.8Sr0.2)2Ca2Cu3O9films were prepared by a spray pyrolysis method on SrTiO3(100) single crystal substrates and on polycrystalline Ag tapes. The biaxially (c- anda-axes) oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9film on SrTiO3single crystal substrate showed very high performance of the transportJc, i.e. 2.8×105A/cm2at 77 K, 0 T and 5.0×104A/cm2at 77 K, 1 T (H//c- axis). In contrast, thec-axis oriented film was obtained on Ag tape with theJcof 8.0×104A/cm2, at 77 K, 0 T, and of 6.9×103A/cm2, at 77 K, 1 T (H//c- axis). In thec-axis oriented Tl1(Ba0.8Sr0.2)2Ca2Cu3O9film, the weak link behavior remained, however the weak magnetic field dependence of theJcand the very highJcin the biaxially oriented film suggested that the weak link problem was eliminated. We concluded it would be necessary to get the biaxial orientation to produce practical wires of Tl-1223.
Influence of Crystal Strain on Superconductivity of a-Axis Oriented YBa2Cu3Ox Films
Authors: Ito Wataru , Mahajan Sukesh , Yoshida Yukihisa , Morishita Tadataka , Kumagai Masao , Yabuta Konami
Published: October 2002

Ion channeling measurements were executed to evaluate the crystal strain in a-axis
oriented YBa2Cu3O

x

(YBCO) films with different film thicknesses.
The average Ba-Ba distance in the film plane as determined from the channeling angle
of the Ba atomic row in the <110> (and <301>) direction
was found to be close to the lattice constant of the SrTiO3 substrate regardless
of the film thickness. A similar result was also obtained for oxygen atoms. These results
indicate that the films grow while matching their lattice constant to that of the substrate.
The simultaneous strain relief induced by the increase in film thickness was suggested
from the channeling yield in the obtained dip curve. Furthermore, the relaxed grain was
confirmed near the surface of the 3500 Å film from the Ba <301> axial
channeling. The influence of the crystal strain on the superconductivity of the
a-axis oriented YBCO films is explained on the basis of variation in the site of apical oxygen.
Kinetic Inductance of Superconducting Coplanar Waveguides
Authors: Watanabe Koki , Yoshida Keiji , Kohjiro Takeshi Aoki
Published: October 2002

An analytical expression for the kinetic inductance of the superconducting coplanar
waveguide is given using the conformal mapping technique. This expression is shown
to be in good agreement with experimental results obtained from the temperature dependence
of the resonant frequency of the NbN coplanar waveguide resonators, especially in the
case of a film thickness smaller than the magnetic penetration depth. It is also
shown that the magnetic penetration depth of the superconducting thin films can be evaluated by this method.
Ferromagnetism of Organic Radical Crystals
Authors: Minoru Kinoshita Minoru Kinoshita
Published: October 2002

Recently, the transition to ferromagnetic order has been found in crystals of
organic compounds not containing metallic elements. The progress of the research is
reviewed starting from the initial stage of study to obtain the design strategies to
induce ferromagnetic interaction in organic crystals to the discovery of ferromagnetism in
p-nitrophenyl nitronyl nitroxide ( p-NPNN; C13H16N3O4).
The recent development in the field of molecular magnetism is also described.
Magnetoresistance Effects in Spin-Valve Multilayers Including Three Ni–Fe–Co Layers
Authors: Noguchi Shin , Nakatani Ryoichi , Katsumi Hoshino Katsumi Hoshino , Yutaka Sugita Yutaka Sugita
Published: October 2002

Magnetoresistance effects have been investigated in spin-valve multilayers including
three Ni–Fe–Co layers. The layered structure of the spin-valve multilayers are
[AF1/Ni–Fe–Co/Cu/Ni–Fe–Co/Cu/Ni–Fe–Co/AF2/Si], where AF1 and AF2 are antiferromagnetic layers.
The spin-valve multilayers including three Ni–Fe–Co layers show magneto-resistance ratios
Δρ/ρ of 3.7% and 5.6% at around 1.5 kA/m. These values are higher
than the 2.2% of a spin-valve sandwich that includes two Ni–Fe–Co layers, [Ni–Fe–Co/Cu/Ni–Fe–Co/Fe–Mn/Cu/Hf/Si]. It is found
that the total resistivity changes (Δρ) of the spin-valve multilayers including
three Ni–Fe–Co layers are twice that for the spin-valve sandwich that includes two
Ni–Fe–Co layers. This is due to the fact that the number of Ni–Fe–Co/Cu interfaces
in the spin-valve multilayers that include three Ni–Fe–Co layers is double that in the
spin-valve sandwich that includes two Ni–Fe–Co layers.
Pulsed and cw-ESR Studies of CO2
- in CaCO3 Irradiated by He+ and γ-Rays for ESR Dating
Authors: Kohno Hideo , Chihiro Yamanaka Chihiro Yamanaka , Motoji Ikeya Motoji Ikeya
Published: October 2002

Orthorhombic CO2
- produced by γ- and He+-irradiation
in aragonite has been measured by electron spin resonance (ESR). An α/γ
effectiveness ratio in producing defects, k-value, of 0.0027±0.0011 was
obtained from the growth curve. Pulsed ESR provided the spin-spin relaxation times,
T
2=1.25±0.04 µ s for orthorhombic CO2
- in γ-irradiated
modern coral and T
2=1.58±0.02 µ s in nonirradiated fossil shell. The
signal of the isotropic CO2
- is found to be almost removed in the field
sweep electron spin echo (ESE) spectrum, and the selective detection of orthorhombic
CO2
- becomes possible. ESR dating and dosimetry can be performed for impurity-included carbonates whose spectra are superposed using the ESE technique.
Structural Properties of Some Cyanoethenes with Optical Nonlinearity
Authors: Arai Hisako , Higashigaki Yoshiyuki , Gotoh Midori , Seiki Yano Seiki Yano
Published: October 2002

An α-cyanostilbene crystal showing optical nonlinearity was examined to be
compared with a non-optically active crystal, with emphasis on the structural aspect.
It was suggested that the introduction of bulky substituents such dimethylamino and
methoxy groups into the cyanostyrene conjugation system was effective to get macroscopic
optical nonlinearity, based on the chemical synthesis and structural analysis. It was
also stressed that the quadrupole interaction in α-cyanostilbenes was one of the important
factors responsible for a nonsymmetric molecular arrangement for the second order optical nonlinearity.
ZnCdSe/ZnSe Quantum-Well Laser Diode on a (711)A GaAs Substrate
Authors: Ohno Tetsuichiro , Kawaguchi Yoshihiro , Akira Ohki Akira Ohki , Takashi Matsuoka Takashi Matsuoka
Published: October 2002

For the purpose of increasing the acceptor concentration in p-type ZnSe, nitrogen-doped
ZnSe was grown on ( n11) GaAs substrates. An acceptor concentration twice as large
as that on a (100) substrate was obtained and found to be reproducible, except for (111)
substrates, on which ZnSe films showed high resistivity. The PL characteristics of ZnCdSe/ZnSe
single quantum wells (SQWs) on a ( n11) substrate were also examined. The PL
spectrum showed a blue shift mainly caused by the smaller Cd composition on a ( n11)
substrate than that on a (100) substrate. Finally, a ZnCdSe/ZnSe MQW SCH laser with
HR-coated facets, a 900-µ m-long cavity, and a 20-µ m
stripe contact was fabricated on a (711)A substrate. The built-in voltage of a LD on the
(711)A substrate is 5 V lower than a LD on the (100) substrate. The former oscillated
under pulsed operation at 25°C with a threshold current of 3.1 A and an
oscillation wavelength of 501 nm.