bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of the Josephoson Junction Array Voltage Standard in Industry
Authors: Yoshida Haruo , Katada Fumio , Sakamoto Yasuhiko , Iwasa Akio , Endo Tadashi
Published: February 2005

A novel trial for use of a fully automated Josephson-junction-array-voltage-standard (JJAVS) system in industry has been carried out since January 1991. Long-term performance tests show that the JJAVS system is available as an industrial-use voltage standard with an accuracy of 0.01 ppm as well as for use in the national laboratory.
Time Domain Spectroscopy for Electrical Properties of a Slightly Reduced Rutile Crystal
Authors: Baba Kenzo , Tsunekawa Shin , Fukuda Tsuguo , Takagi Tasuku
Published: February 2005

A method of measuring the electrical properties of conductive materials by a lumped-capacitance time-domain spectroscopy is described. The properties of a slightly reduced rutile crystal are investigated in the temperature range between 100 K and 290 K. Reflected waves from the sample, observed by a time domain reflectometer, are analyzed by separating the imaginary part of the complex permittivity into two terms; one term characterizes dc electric conductivity and the other the dielectric property of the sample. Each dielectric dispersion is represented by a double Cole-Cole type equation. We have obtained dc resistivities which agree well with the results obtained by a four-probe method, using the relationship, by Spenke, between relaxation time and dc resistivity.
Development of AC Calorimetric Method for Thermal Diffusivity Measurement V. Modulated Laser Beam Irradiation
Authors: Kato Ryozo , Hatta Akikazu Maesono
Published: February 2005

In an ac light-irradiation method for measuring thermal diffusivity along the length of the rectangular thin film sample, we developed a method which uses a modulated laser beam. The laser beam was swept with a high frequency so as to cover the width of the sample. Such a procedure makes possible to obtain uniform ac thermal energy distribution in the direction perpendicular to the direction of ac temperature-wave propagation. Furthermore, it gives rise to a nonuniform ac thermal energy distribution in the direction along the direction of ac temperature-wave propagation. It is theoretically proven that the latter inhomogeneity does not affect the determination of thermal diffusivity. This fact is verified by experiment.
Characterization of Separation-by-Implanted-Oxygen Wafers with Monoenergetic Positron Beams
Authors: Uedono Akira , Wei Long , Tanigawa Shoichiro , Suzuki Ryoichi , Ohgaki Hideaki , Mikado Tomohisa , Kametani Hitoshi , Akiyama Hajime , Yamaguchi Yasuo , Koumaru Masaki
Published: February 2005

Defects in separation-by-implanted-oxygen wafers were studied with monoenergetic positron beams. Doppler broadening profiles of the positron annihilation radiation and lifetimes of positrons were measured as a function of incident positron energy for 200-keV O+-ion implanted Si specimens. For as-implanted specimens, the dominant defect species at a depth of ∼20 nm was identified as vacancy-clusters and that in the region between ∼200 nm and ∼600 nm as vacancy-oxygen complexes. After annealing treatment, the formation of an oxide layer was observed in the region where a great number of vacancy-oxygen complexes formed. It was also found that interstitial Si atoms accumulated at the Si/SiO2 interface.
Ultrahigh Purity Liquid Phase Epitaxial Growth of GaAs
Authors: Amano Toshimasa , Kondo Susumu , Haruo Nagai Haruo Nagai , Susumu Maruyama Susumu Maruyama
Published: February 2005

Ultrahigh purity GaAs reproducibly grown by liquid phase epitaxy is reported. The attained purities, as represented by 77-K electron concentration as low as 4.1×1012 cm-3 and mobility as high as 287000 cm2/Vs for n-type, and hole concentration as low as 2.6×1012 cm-3 and hole mobility as high as 21200 cm2/Vs for p-type, are the highest reported so far. These high mobilities appear to be attainable only by conventional solution baking in hydrogen with a wide O2 concentration range of 0.007-1.34 ppm at 800°C for a time proportional to W
4/3, where W is Ga quantity. Whether we get the UHP p- or n-type depends on a critical term which is peculiar to the Ga quality. Secondary ion mass spectrography trace profile analyses show that the impurities effectively eliminated during the solution baking are S, Si and even C.
Influence of Hydrogen on Electrical Characteristics of Poly-Si Resistor
Authors: Nakabayashi Masakazu , Daikoku Masaaki Ikegami
Published: February 2005

This paper shows that different amounts of hydrogen are absorbed into polycrystalline silicon (Poly-Si) film depending on its Structures such as oxide film under Poly-Si film and metallization pattern on Poly-Si film. We examined how hydrogen affected the conductive mechanism of Poly-Si film, and measured the absorption of hydrogen into Poly-Si film by elastic recoil detection analysis (ERDA). Our investigations revealed that the change in Poly-Si film resistance was caused by a decrease in trap density, which occurred when dangling bonds were filled with hydrogen. This hydrogen was due to diffusion of hydrogen in plasma-enhanced chemical-vapor-deposited silicon nitride (P-SiN) film. It was confirmed that the absorption of hydrogen was the cause of the decrease in resistance using ERDA.
Reduction of Leakage Current and Minority Carrier Lifetime in Platinum-Diffused pn Diodes
Authors: Pahlawan Sagala Pahlawan Sagala , Hiroshi Kuwano Hiroshi Kuwano
Published: February 2005

We propose a novel method to control the depth profiles of platinum-related trap concentration in platinum-diffused silicon p
+
n diodes and to improve their electrical properties, leakage current and lifetime. Platinum has been introduced into silicon wafers and p
+
n diodes by one- or two-step heat treatment. The experimental results show that we can simultaneously minimize the leakage current and minority carrier lifetime, especially by the two-step heat treatment. This is the first proposal to overcome the trade-off relationship between the leakage current and lifetime. The experiment also proves that the dominant level for both the leakage current and minority carrier lifetime is a level at Ec-0.52 eV.
Optical Constants of In1-xGaxSb Ternary Alloys: Experiment and Modeling
Authors: Shun Imai Shun Imai , Sadao Adachi Sadao Adachi
Published: February 2005

The optical response of In1-x
Ga
x
Sb ternary alloys in the 1.5-5.4-eV photon-energy range at room temperature is measured by spectroscopic ellipsometry (SE). The measured SE data show distinct structures at energies of the E
1, E
1+Δ1, E
0
′, E
0
′+Δ0
′, E
2 and E
1
′ critical points. These spectra are analyzed on the basis of a simplified model of interband transitions. The model proposed here enables us to obtain the optical response in In1-x
Ga
x
Sb alloys of arbitrary composition (x) and photon energy (E=\hbarω). Results of the surface-treatment effect on the pseudodielectric functions are also presented.
Frame Sequential Color Thin Film Transistor/Liquid Crystal Displays: Display Characteristics and Grayscale Consideration
Authors: Hiap Liew Ong Hiap Liew Ong
Published: February 2005

We report a theoretical study on the optical characteristics of a frame sequential color thin film transistor/liquid crystal display (TFT/LCD) operating with the TN LCD. Important liquid crystal (LC) and display parameters (cell gap, LC surface pretilt angle, applied voltage, LC viscosity, frame rate, and operation sequence) are considered and optimized to improve the display performances. Both the modeling and experimental results for a TN LCD using an EM Merck ZLI-3651 LC material are presented. We also present detailed theoretical results for a TFT/LCD operating at frame rates of 30 Hz and 71 Hz. Sufficiently fast switching-on and switching-off dynamic responses can be obtained by raising the temperature to 40-60°C to reduce the LC rotational viscosity. A display operating at the 71 Hz frame rate, can obtain a good bi-level display, but it is difficult to obtain a good display with 512 colors.
Domains and Vortical Flows in a Nematic Phenyl Benzoate Under Transverse Electric Fields
Authors: Kanakapura Seshappa Krishnamurthy Kanakapura Seshappa Krishnamurthy , Rengasamy Balakrishnan Rengasamy Balakrishnan
Published: February 2005

Electrohydrodynamic instabilities have been investigated for an initially homogeneously aligned nematic with a positive dielectric anisotropy, employing the transverse geometry. Optical threshold corresponds to the onset of out-of-plane director deviations and is higher than the threshold derived from transient responses; the latter shows a non-linear increase with electrode separation. Along the flow lines, the degree of distortion varies continuously. These results do not seem to follow completely from the known models of the instabilities.
Flux Growth and Characterization of α-57Fe2O3 Single Crystals for Nuclear Bragg Scattering Optical Components
Authors: Suzuki Carlos K. , Takei Humihiko , Sakai Fumiko , Yoda Yoshitaka , Zhang Xiao W. , Mitsui Takaya , Kudo Yoshihiro , Izumi Koichi , Ishikawa Tetsuya , Sugiyama Hiroshi , Ando Masami , Ohno Hideo , Harami Taikan , Matsushita Tadashi , Kikuta Seishi
Published: February 2005

57Fe-enriched hematite, α-57Fe2O3, single crystals for the X-ray optical components of nuclear Bragg scattering (NBS) have been successfully grown by the PbO-V2O5 flux method. The X-ray rocking curves for selected areas obtained by the double-crystal method reveal that the minimum value of full width at half-maximum for the rhombohedral (6 6 6)r reflection is 2.3 arcs for λ=1.12 Å. Two types of imperfections, slight bending and sector zoning are observed in the crystals by precise X-ray topography and gonlometry. The maximum counting rate of NBS (14.4 eV photons) using the best crystal with (7 7 7)r reflection is as high as 20000 cps, which has been observed using the X-ray beam from the synchrotron radiation of TRISTAN, at National Laboratory for High Energy Physics (KEK), Tsukuba.
Nucleation of Oxygen Precipitates during Cooling Processes in Czochralski Silicon
Authors: Hideki Yamanaka Hideki Yamanaka
Published: February 2005

Cooling simulation indicates that there are two types of nucleation paths during cooling to 400°C from 1250°C. One type of nucleation path is initiated at temperatures around 550°C independent of thermal histories above 550°C. The nuclei originate either from carbon-oxygen complexes or from thermal-donor-related oxygen aggregates. The other type is initiated at temperatures around 1000°C, leading to the formation of embryos which originate from carbon-related oxygen aggregates, some of which can grow into nuclei during cooling below 550°C. In the wafers withdrawn from the furnace at above 1000°C in nitrogen, nucleation is enhanced by 400-750°C annealing. The enhancement in the 400-550°C range is caused by the accumulation of migrating nitrogen on the surfaces of the nuclei above. The enhancement in the 550-750°C range is mainly caused by the formation of nitrogen-oxygen complexes.
Switching Kinetics of Pb(Zr, Ti)O3 Thin Films Grown by Chemical Vapor Deposition
Authors: Katayama Takuma , Masaru Shimizu Masaru Shimizu , Tadashi Shiosaki Tadashi Shiosaki
Published: February 2005

The pulse switching kinetics of ferroelectric Pb(Zr, Ti)O3 thin films grown by chemical vapor deposition (CVD) has been investigated. The switching time was proven to be proportional to the electrode area of the thin-film capacitor under our measurement conditions. Polarization switching was also characterized by the exponential functions of reciprocal voltage. On the basis of the experimental results, the relationships among the apparent switching phenomena, the nucleation process of reversed domains and the time constant of the measurement system are discussed. Moreover, the switching time determined by the low nucleation rate is formulated.
Investigation of Cathodoluminescent Display Device with Field Emission Cathodes
Authors: Itoh Shigeo , Watanabe Teruo , Ohtsu Kazuyoshi , Mikio Yokoyama Mikio Yokoyama , Masateru Taniguchi Masateru Taniguchi
Published: February 2005

The purpose of this paper is to investigate the applicability of field emission (FE) cathode arrays for a cathodoluminescent display device. We proposed a tetrode structure which has a grid inserted between the Mo emitter FE cathode arrays and the anode. The focusing properties of electron beams were measured using the Y2SiO5:Tb phosphor, and a green emission of about 66,700 cd/m2 was achieved at the anode current of about 90 mA/cm2 and the anode voltage of 8 kV in a vacuum chamber kept at 1×10-9 Torr, in which 14,700 Spindt-type cathode tips were used. The experimental results showed that the dispersion of electron beams can be controlled to a considerable extent by the shape, distance and voltage of the grid. An effect of SO2 gas on the emission property of FE cathode arrays was measured, too.
Effect of Ion Implantations and Post-treatments on Optical Transmission of Fluorozirconate Glass
Authors: Dai Yisheng , Yamaguchi Ichirou , Takahashi Katsuo , Iwaki Masaya
Published: February 2005

This paper is devoted to the study of the optical transmission of fluorozirconate glass implanted with Ar, N and O ions, at low energies from 5 to 15 and high energies of 30, 50 and 100 keV to various dose levels. Ar- and N-ion implantations clearly reduced the transmittance. The transmittance reduction of Ar-ion-implanted glass can be effectively recovered by thermal treatment of the glass in oxygen atmosphere, but not by subsequent oxygen-ion implantation. On the other hand, post O-ion implantation can significantly improve the transmittance of N-ion-implanted glass but thermal oxidation is not effective. The energy and dose conditions do not significantly affect the transmittance of the O-ion-implanted samples, but give rise to the attenuation tail near the UV edge. The origin of the tail is considered to be mainly the defects arising from ion-bombardment-induced atomic displacement. The attenuation from light scattering is substantial only when the energy of implantation is high enough to cause serious surface roughness.
Sub-100 nm Patterning of GaAs Using In Situ Electron Beam Lithography
Authors: Kawanishi Hidenori , Sugimoto Yoshimasa , Nobuyuki Tanaka Nobuyuki Tanaka , Tomonori Ishikawa Tomonori Ishikawa
Published: February 2005

Patterning of GaAs at the sub-100 nm size has been demonstrated using in situ electron beam (EB) lithography processes. Patterning is carried out by EB exposure of an ultrathin oxide layer on GaAs which is used as a mask material. The patterns are transferred into GaAs by Cl2 gas etching. A high-brightness Schottky electron gun is used in the exposure process. The size of the etched feature is as small as 50 nm, which is equal to the diameter of the electron beam. The results show that in situ EB lithography processes using an ultrathin oxide mask are very promising for fabricating nanometer-scale structures.
Effect of Zr/Ti Ratio on Crystal Structure of Thin Lead Zirconate-Titanate Films Prepared by Reactive Sputtering
Authors: Fujisawa Akira , Furihata Masahiro , Minemura Isamu , Fukami Yoshio Onuma
Published: February 2005

Thin lead zirconate-titanate (PZT) films have been synthesized on MgO(100) using the tripole magnetron sputtering system. This system makes it possible to sputter lead and zirconium-titanium alternately. Lead concentration in the deposited films can be easily adjusted to near stoichiometry through the control of substrate temperature. The c-axis-oriented films with perovskite structure of Morphotropic Phase Boundary composition were obtained at 550°C via the self-limiting process of lead concentration. The formation process of thin PZT films has been investigated with reference to the observed results of the dependence of the crystal structure on Zr/Ti ratio as well as lead concentration in the films.
GHz-Band Surface Acoustic Wave Devices Using Aluminum Nitride Thin Films Deposited by Electron Cyclotron Resonance Dual Ion-Beam Sputtering
Authors: Okano Hiroshi , Tanaka Naoki , Kenichi Shibata Kenichi Shibata , Shoichi Nakano Shoichi Nakano
Published: February 2005

AlN thin films have been deposited on basal plane ((001)Al2O3) and R-plane ((11̄2)Al2O3) sapphire by an ECR dual ion-beam sputtering method. The (001) plane of AlN was epitaxially grown on (001)Al2O3. On the other hand, it was found that the (001) plane of AlN was deposited on (11̄2)Al2O3 with an inclination of about 26 degrees against the substrate, and a surface wave having high coupling and high velocity (6684 m/s) was excited on this substrate. Resonator-type 1.67 GHz band SAW filters have been fabricated using AlN thin film deposited on (11̄2)Al2O3. The insertion loss, suppression and TCD were 7.9 dB, more than 20 dB and 35 ppm/°C, respectively. These are the best values yet in a GHz band SAW filter based on AlN thin film, and are good enough to allow practical use.
Low-Temperature Preparation of Pb(Zr, Ti)O3 Thin Films on (Pb, La)TiO3 Buffer Layer by Multi-Ion-Beam Sputtering
Authors: Kanno Isaku , Hayashi Shigenori , Kamada Takeshi , Masatoshi Kitagawa Masatoshi Kitagawa , Takashi Hirao Takashi Hirao
Published: February 2005

Ferroelectric lead-zirconate-titanate (PZT) thin films were successfully fabricated by the multi-ion-beam sputtering technique in an oxygen ambient at a low substrate temperature of 415°C. By inserting lead-lanthanum-titanate (PLT) buffer layers between substrates and PZT films, the perovskite-PZT thin films could be epitaxially grown on (100)MgO, (100)Pt/MgO and (111)Pt/Ti/SiO2/Si substrates. These films, even at thickness values of as low as 630 Å, showed excellent ferroelectric properties with a remanent polarization of 20 µC/cm2, coercive field of 200 kV/cm, and a relative dielectric constant of 700.
Preparation and Properties of (Pb, La)TiO3 Pyroelectric Thin Films by RF-Magnetron Sputtering
Authors: Nagao Nobuaki , Takayuki Takeuchi Takayuki Takeuchi , Kenji Iijima Kenji Iijima
Published: February 2005

The c-axis-oriented Pb0.85La0.15Ti0.96O3 (PLT) thin films appropriate for the infrared sensor utilized in environmental monitoring were successfully obtained by rf-magnetron sputtering. The effects of sputtering conditions on the thin film growth were studied. Highly c-axis-oriented films were prepared under the most suitable sputtering conditions. Those films showed extremely large pyroelectric coefficient of 1.3×10-7 C/cm2 K and relatively small dielectric constant of 350 (1 kHz) at room temperature. Dielectric and ferroelectric properties of the film were also reported.
Preparation and Basic Properties of BaTiO3-BaPbO3 Multilayer Thin Films by Metal-Alkoxides Method
Authors: Azuma Takahiro , Sheiji Takahashi Sheiji Takahashi , Makoto Kuwabara Makoto Kuwabara
Published: February 2005

Preferentially oriented barium titanate (BTO)-barium metaplumbate (BPO) multilayer thin films were prepared by the metal-alkoxides method on MgO single crystals. The BPO layer is an electrode for the BTO layer. Thin films were deposited on cleaved MgO (100) substrates by spin coating. A BTO film of 0.4 µm thickness on the BPO layer shows a dielectric constant of about 400 at room temperature. No formation of reaction phases between BTO and BPO, fired at 800°C to yield a well-crystallized BTO film, was detected in X-ray diffraction analysis.
Preparation and Properties of Ferroelectric BaTiO3 Thin Films by Sol-Gel Process
Authors: Hayashi Takashi , Ohji Naoto , Hirohara Koichiro , Tsuneshi Fukunaga Tsuneshi Fukunaga , Hiroshi Maiwa Hiroshi Maiwa
Published: February 2005

Ferroelectric BaTiO3 thin films have been successfully prepared by sol-gel process using barium and titanium isopropoxides as precursor solutions for dip-coating. Homogeneous BaTiO3 thin films have been obtained on various substrates by preheating gel films at 120°C in a flow of oxygen/water vapor mixed gas, and successive heating at 650°C in oxygen atmosphere. The introduction of water vapor during preheating is very effective for the crystallization of BaTiO3 at relatively low temperatures. These films exhibit good crystallinity and smooth surfaces with grains as small as about 50 nm. BaTiO3 thin films prepared on Pt/SiO2/Si substrates with a thickness of about 0.5 µm show dielectric constants of 800∼1000 and loss tangents of 0.07∼0.09 at 1 kHz. Ferroelectric hysteresis loops were observed for these thin films which possessed the remanent polarization of 8 µC/cm2 and the coercive field of 25 kV/cm.
Comparative Study of Amorphous and Crystalline (Ba, Sr)TiO3 Thin Films Deposited by Laser Ablation
Authors: Bhattacharya Pijush , Komeda Tadahiro , Kyung-ho Park Kyung-ho Park , Yasushiro Nishioka Yasushiro Nishioka
Published: February 2005

(Ba0.5Sr0.5)TiO3 thin films (200-300 nm) were deposited on Pt-coated Si substrates by laser ablation at 500 and 650°C. The leakage currents of crystalline films grown at 650°C were found to be higher than those of amorphous films grown at 500°C. The crystalline thin films showed higher surface roughness than the amorphous films as measured by atomic force microscopy (AFM). A columnar grain structure was observed for crystalline films with a grain size of 20-30 nm by transmission electron microscope (TEM) analysis. These factors may be responsible for high leakage currents of crystalline films. Constant current injection measurements for Au/(Ba0.5Sr0.5)TiO3/Pt capacitors showed that electron trapping states near the top electrode interface were higher in number than at bottom electrode interface. This may be due to the presence of reactive sites on the surface of deposited films as observed by X-ray photoelectron spectroscopy (XPS) measurements.
Electrical and Crystallographic Properties of Sputtered-Pb(Zr, Ti)O3 Films Treated by Rapid Thermal Annealing
Authors: Yamauchi Satoshi , Tamura Hiroyuki , Masaki Yoshimaru Masaki Yoshimaru , Masayoshi Ino Masayoshi Ino
Published: February 2005

Pyrochlore-phase lead-zirconate-titanate (PZT) films were prepared by rf-magnetron sputtering using a multi-element metal target at 400°C. These films were crystallized to the perovskite phase by rapid thermal annealing (RTA) at 600°C for a few minutes. The RTA-treated PZT films had not only extremely smooth surfaces but also tenfold stronger X-ray diffraction peak intensities of the perovskite structure than those of furnace-annealed films which had with rough undulation. The electrical properties of RTA-treated films indicated good ferroelectric properties. The remanent polarization and coercive field of the 100 nm-thick RTA-treated film were 15 µC/cm2 and 67 kV/cm, respectively. Fatigue measurements with alternating ±3 V pulses showed that the film was stable up to 109 cycles.
Micro-Patterning of PbZrxTi1-xO3 Thin Films Prepared by Photo Sensitive Sol-Gel Solution
Authors: Nakao Yuichi , Nakamura Takashi , Hoshiba Kazuhiro , Sameshima Katsumi , Kamisawa Akira , Kohji Abe Kohji Abe , Nobuyuki Soyama Nobuyuki Soyama , Katsumi Ogi Katsumi Ogi
Published: February 2005

The photo sensitivity of sol-gel solution of PbZr
x
Ti1-x
O3 (PZT) was studied. A coated film of the sol-gel solution on Pt/Ti/SiO2/Si substrates was exposed to an excimer laser and developed with water. The film was finally annealed at 700°C for 60 s by rapid thermal annealing (RTA). Ferroelectric perovskite phase was observed in the PZT thin films. The 130-nm-thick film showed P
r of 11.2 µ C/cm2 and E
c of 93.8 kV/cm. From this process, half-micron patterns of PZT films were obtained.
Synthesis and Characterization of Bi4Ti3O12 Thin Films by Sol-Gel Processing
Authors: Toyoda Masahiro , Hamaji Yukio , Payne Kunisaburo Tomono
Published: February 2005

Stoichiometric Bi4Ti3O12 thin films were prepared by sol-gel processing. This paper discusses the synthesis of polymerizable solutions containing Bi and Ti, and characterization of the resulting Bi4Ti3O12 thin films. The formation of metallic alkoxide and acetate alkoxide are indispensable, soluble precursors for these multicomponent systems. The double alkoxide was prepared by allowing Bi acetate to react with Ti alkoxides. The development of the polymerizable solution system containing Bi and Ti required choosing appropriate solvents and metallo-organic sources for the two components. Bismuth acetate, titanium methoxyethoxide and 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. These films were later characterized by X-ray diffraction and SEM. The measured dielectric and ferroelectric properties of Bi4Ti3O12 were as follows: dielectric constant 120, dielectric loss 0.5%, remanent polarization P
r=4 µC/cm2, coercive field E
c=1.8 kV/cm.
Evaluation of Imprint Properties in Sol-Gel Ferroelectric Pb(ZrTi)O3 Thin-Film Capacitors
Authors: Mihara Takashi , Araujo Hitoshi Watanabe
Published: February 2005

Studies of imprint properties have been carried out by electrical evaluation with pulse switching response and circuit modeling on sol-gel lead zirconate titanate (PZT) ferroelectric thin-film capacitors. The imprint properties were evaluated by measuring the switched and nonswitched charges after three different operations at high temperature, which consist of (1) fatigue by cumulative bipolar pulses, (2) exposure to a large number of positive unipolar pulses, and (3) exposure to a large number of negative unipolar pulses. The nonswitched charge without polarization reversal after being exposed to a large number of unipolar pulses was increased to be greater than switched charge with polarization reversal. This causes the decrease of a noise margin when the memory cell is read. This phenomenon is enhanced by the sample temperature above 75°C, the pulse height, and the amount of cumulative fatigue cycles before imprint. This phenomenon is also found in the Nb-doped PZT capacitor, which is a candidate for fatigue-free materials.
BaTiO3 Films for Silicon-on-Insulator Structure
Authors: Yamanashi Akira , Tanaka Keiichi , Takao Nagatomo Takao Nagatomo , Osamu Omoto Osamu Omoto
Published: February 2005

The physical properties of BaTiO3 films deposited onto (100)-oriented silicon wafers at a low substrate temperature of 350°C for fabricating silicon-on-insulator (SOI) structures are described. These films were prepared by rf planar magnetron sputtering using a target of BaTiO3 ceramic. These films did not exhibit ferroelectricity, and the dielectric constant εs and the dissipation factor tan δ were about 100 and 0.013, respectively. These films showed a breakdown field larger than 1×106 V/cm and were excellent insulators. Thin-film transistors were fabricated using a silicon film deposited onto the BaTiO3 film. The field effect mobility of 34 cm2/Vs was obtained.
Fabrication of Ferroelectric BaTiO3 Films by Electrophoretic Deposition
Authors: Okamura Soichiro , Koura Takeyo Tsukamoto
Published: February 2005

BaTiO3 thick films on Pt substrates were fabricated by the electrophoretic deposition method. The suspension was prepared with fine powder (0.1 µm in diameter) of BaTiO3, acetone and iodine. Dense and strong films were formed in an applied DC field of 500 V/cm. The films sintered at 1200°C were crystallized into the tetragonal phase at room temperature. The coercive field E
c and the remanent polarization P
r were estimated to be 1.6 kV/cm and 2.1 µC/cm2, respectively, from the P-E hysteresis loop observation.
Vibratory Characteristics of Newly Designed Fork-Type Piezoactuator
Authors: Noriaki Yamada Noriaki Yamada , Terumasa Kato Terumasa Kato
Published: February 2005

Characteristics of a newly designed fork-type piezoactuator used in a parts feeder was investigated. This actuator consisted of two bimorphs using lead zirconate titanate ceramics, which were linked to each end in the shape of a fork. Vibration displacements of the fork-type actuator were measured optically and analyzed into vibration modes. The fork-type actuator had the advantage in that it transmits less power to a base than a conventional bimorph-type actuator.
Humidity Sensor Using Surface Acoustic Wave Delay Line with Hygroscopic Dielectric Film
Authors: Nomura Tooru , Oobuchi Ken , Furukawa Tsutomu Yasuda
Published: February 2005

A surface acoustic wave (SAW) sensor for measurement of humidity in ambient atmosphere is presented. SAW technology is increasingly being used in sensors. The majority of the work reported on SAW sensors to date has studied the effect of mass loading. In this paper, we propose a new SAW humidity sensor that uses the changes in the film permittivity rather than the mass. A 30 MHz dual SAW delay line fabricated on 128° YX LiNbO3 was coated with cellulose acetate. This hygroscopic polymer coating caused a SAW velocity change of 0.36 m/s per 10% relative humidity. The response was linear in the range from 10% to 80% in relative humidity.
Array Transducer Composed of Porous Ceramic Rectangular Prism
Authors: Susumu Kumamoto Susumu Kumamoto , Kiyonori Okuno Kiyonori Okuno
Published: February 2005

The 9×3 array transducer composed of porous ceramics is fabricated and the acoustic sensitivity is measured. A low Q value of 7.5 is obtained in the longitudinal vibration mode.
Solid-Solution (Bi1-xPbx)(Ni(1-x)/2Ti(1+x)/2)O3for New Piezoelectric Ceramics
Authors: Tadashi Takenaka Tadashi Takenaka , Masatoshi Yamada Masatoshi Yamada
Published: February 2005

A new solid solution, (Bi1-xPbx)(Ni(1-x)/2Ti(1+x)/2)O3(BPNT-100x) (0.3≤x≤0.5), is studied for their dielectric, ferroelectric, piezoelectric and mechanical properties as a new group of piezoelectric ceramics. The crystal phase of the solid solution is a perovskite structure withx≥0.3. The BPNT-100xsystem has a morphotropic phase boundary between a rhombohedral phase and a tetragonal phase atx=0.445. The Curie temperature,Tc, is over 400°C and the dielectric constant, εs, is larger than 600 at room temperature. D-E hysteresis loops are observed with large remanent polarization,Pr≥30 µC/cm2, and a coercive field,Ec≤45 kV/cm. The electromechanical coupling factors,k33andk31, in the longitudinal and the transverse modes are 50.3% and 23.8% atx=0.5 (BPNT-50), respectively. The mechanical strength and hardness were higher than those of the conventional PZT system.
Tensile Stress-Strain Behavior of Piezoelectric Ceramics
Authors: Tanimoto Toshio , Kiyoshi Okazaki Kiyoshi Okazaki , Kohji Yamamoto Kohji Yamamoto
Published: February 2005

Fracture strength and stress-strain behavior under tensile stress in piezoelectric ceramics have been investigated with special emphasis on the effects of poling conditions. The materials used in this work are the commercial piezoelectric ceramics, PbZrO3-PbTiO3 (PZT) and BaTiO3. First, an attempt was made to evaluate the tensile strength properties of samples having a specially designed specimen geometry. In the actual tensile test, fracture did not occur at the gripping portion at all, indicating usefulness of the present tensile test method. Not only fracture strength, but also elastic properties, tensile modulus and Poisson's ratio, were evaluated. Second, an investigation was performed on the stress-strain behavior under tension in this material. As a result, stress-strain response under tension was confirmed to be nonlinear. The nonlinearity in the stress-strain relationship under compression loading has already been reported by some investigators. However, very little work has been done on the tensile stress-strain relationship studied in this paper. Third, acoustic emission monitoring was performed simultaneously during tensile tests, and thus the tensile failure process in piezoelectric ceramics was discussed.
Fabrication of Multilayer Barrier Layer Capacitors with Semiconducting (Ba, Sr)TiO3 Ceramics
Authors: Itoh Tatsuhiko , Shinjiro Tashiro Shinjiro Tashiro , Hideji Igarashi Hideji Igarashi
Published: February 2005

Multilayer barrier layer capacitors were successfully fabricated by utilizing potential barriers at grain boundaries of semiconducting (Ba,Sr)TiO3 ceramics in the temperature region above the Curie point of -140°C. A small amount of Mn improved the dissipation factor and temperature dependence of permittivity in the temperature region from -30°C to 100°C. Multilayer barrier layer capacitors were composed of 10 layers having 80-µm thickness per layer. Resistivity above 1010 Ω·cm was attained at room temperature, and relative permittivities above 5500 and dissipation factors less than 2% were obtained in the temperature region from -30°C to 100°C.
Electron Emission from PZT Ceramic by External Pulsed Electric Fields -Pulse Voltage Dependence of Emitted Charge-
Authors: Asano Jun-ichi , Iwasaki Shin-ya , Masanori Okuyama Masanori Okuyama , Yoshihiro Hamakawa Yoshihiro Hamakawa
Published: February 2005

Electron emission into vacuum from a thin plate of lead-zirconate-titanate (PZT) ferroelectric ceramic has been observed under various applied pulse conditions. As positive pulse voltage of a couple of bipolar pulse trains increases, the emitted charge increases, but saturates over +150 V, and the absolute threshold voltage of negative pulse for the electron emission decreases. Hence this electron emission depends strongly on the external pulse voltage, and polarization change exerts an important effect on this phenomenon. Cathodoluminescence from phosphor excited by the emitted electrons has also been observed and may be useful in the application to an electron emitter in vacuum electronic devices.
Electro-Optical Effect of Bi4Ge3O12 Crystals for Optical Voltage Sensors
Authors: Osamu Kamada Osamu Kamada , Kazuhiko Kakishita Kazuhiko Kakishita
Published: February 2005

The electro-optical coefficient r
41 of Bi4Ge3O12, corresponding to the sensitivity of the optical voltage sensor, and the temperature dependence of response characteristics to applied step voltage are studied. From these measurements, two kinds of dc drift are found to exist in Bi4Ge3O12 crystals. One is found to be due to the relaxation of the piezoelectric polarization (type (a)), and the other is explained as the deduction phenomenon by the thermally induced space-charge field (type (b)). By correcting for dc drift of type (a), the accurate value of r
41=1.09×10-12 m/V is obtained at 855 nm wavelength.
Composition Dependence of Electrooptic Effects in (Pb, La)(Zr, Ti)O2 Ceramics
Authors: Furuno Kunihiro Nagata
Published: February 2005

Electrooptic ceramics of (Pb, La)(Zr, Ti)O3 were fabricated by a combination of the partial-coprecipitation and doctor-blade methods. The composition dependence of electrical properties and electrooptic effects were investigated. Polarization dependence on the electric field in the D-E hysteresis was somewhat larger in the 8/70/30 composition than that in the 9/65/35 composition. Accordingly, the half-wave voltage and the deflection angle of the 8/70/30 composition were one and a half to two times larger than those of the 9/65/35 composition.
Microwave Dielectric Properties of CaO-Li2O-Ln2O3-TiO2 Ceramics
Authors: Ezaki Kenichi , Baba Yoko , Takahashi Hisakazu , Kenichi Shibata Kenichi Shibata , Shoichi Nakano Shoichi Nakano
Published: February 2005

We have investigated the microwave dielectric properties of the Li2O-Ln2O3-TiO2 system and the CaO-Li2O-Ln2O3-TiO2 system (Ln: Lanthanide), both of which have a perovskite structure. The relationship between the kind of lanthanide element and dielectric properties at microwave frequencies was confirmed. It was also found that the ionic radius of lanthanide ions has a strong influence on the dielectric properties. Excellent dielectric properties of εr=110, f·Q value=4500 GHz and high temperature stability for the resonant frequency at 3 GHz were obtained with a composition of CaO:SrO:Li2O:Sm2O3:TiO2=15.0:1.0:9.0:12.0:63.0 (molar ratio). Also, band-pass filters made of this material were examined. The filters were greatly miniaturized to the size of about 2×5×4 mm3 (0.04 cm3).
Formation of Solid Solutions of New Tungsten Bronze-Type Microwave Dielectric Compounds Ba6-3xR8+2xTi18O54 (R=Nd and Sm, 0≤x≤1)
Authors: Ohsato Hitoshi , Ohhashi Toshiyuki , Nishigaki Susumu , Okuda Takashi , Kazuhiko Sumiya Kazuhiko Sumiya , Shinya Suzuki Shinya Suzuki
Published: February 2005

The formation of solid solutions of microwave dielectric compounds having compositions in the vicinity of Ba3.75-R
9.5Ti18O54 and/or BaO·R
2O3·4TiO2 (R=rare earth) has been investigated. 3BaO·2R
2O3·9TiO2 (Ba6
R
8Ti18O54) solid solutions with the ideal formulae of Ba6-3x

R
8+2x
Ti18O54 (0.0≤x≤1.0) have been derived on the tie line with the ratio Ti:O=1:3 between perovskite and R
2Ti3O9 based on the new tungsten bronze-type crystal structure with 2×2 perovskitelike unit cells. The type of solid solutions is substitutional with following the relation 3Ba2+\rightleftarrows2R
3++\Box. Lattice parameters as a function of composition have been determined by the WPPD (whole-powder-pattern decomposition) method.17) The formation range is located at 0.3≤x≤0.7 compositions in the case of R=Sm and 0.0≤x≤0.7 in R=Nd. In the latter case, two kinds of substitutions of the solid solutions are considered.
Dielectric Properties of Pb-Based Perovskite Substituted by Ti for B-site at Microwave Frequencies
Authors: Kagata Hiroshi , Kato Junichi , Keiji Nishimoto Keiji Nishimoto , Tatsuya Inoue Tatsuya Inoue
Published: February 2005

Substitutions of B-sites by Ti in several Pb-based perovskite ceramics that had high relative permittivities (εr), high Q values, and small temperature coefficients of resonant frequency (τf) were studied in order to control εr and τf independently. It was found that relative permittivities with near-zero τf in (Pb, Ca)(Zr, Ti)O3, (Pb, Ca){(Fe1/2Nb1/2), Ti}O3, and (Pb, Ca){(Mg1/3Nb2/3), Ti}O3 systems could be controlled in the εr regions lower than 105, 95, and 70, respectively. All these systems had sufficiently high Q values. They are applicable to resonant devices for mobile communications.
Field-Induced Phase Transitions in Antiferroelectric Liquid Crystal
Authors: Hatano Jun , Harazaki Masato , Sato Mihoko , Iwauchi Ken'ichi , Saito Shin'ichi , Murashiro Katsuyuki
Published: February 2005

Cell thickness dependence and field impression rate dependence of field-induced phase transition in an antiferroelectric liquid crystal (MHPOBC) have been investigated by observing the optical transmittance hysteresis loop and texture of the cells. In thin cells, pseudo-triple hysteresis loops due to coexistence of ferroelectric and antiferroelectric domains have been observed. In thick cells, an antiferroelectric phase is stabilized near the zero-field region of a ferrielectric phase of a field-temperature phase diagram. A possible model for molecular orientational structure of the phases and field-induced transitions among them is discussed on the basis of these experimental results.
Crystal Structure Refinement of (Pb1-xCax)ZrO3 by the Rietvelt Method
Authors: Kato Junichi , Fujii Masaru , Hiroshi Kagata Hiroshi Kagata , Keiji Nishimoto Keiji Nishimoto
Published: February 2005

Superlattice structures in rhombohedral perovskite (Pb1-x
Ca
x
)ZrO3, which has high dielectric constant with small temperature coefficient and high Q value at microwave frequencies, were refined by the X-ray Rietvelt powder profile analysis. The superlattice structure is caused by slight displacement of lead and zirconium ions from the ideal perovskite sites, together with twisting and deformation of oxygen octahedra. The Q value of (PbCa)ZrO3 at microwave frequencies has no relation to the formation of the superlattice structures, as indicated by the absence of cation ordering.
Electrical Conductivity of Tetrapod-Shaped ZnO Whiskers
Authors: Mitsumasa Oku Mitsumasa Oku
Published: February 2005

The electrical conductivity of tetrapod-shaped ZnO whiskers was measured under different atmospheric conditions. Apparent resistivity of 104∼108 Ω·cm was obtained in the form of the compressed whisker powder. The conductivity was found to depend strongly on the compressive pressure, the electrical field strength and the atmosphere. The rectification effect was observed in current-voltage measurements of the whiskers using a pair of parallel-plane electrodes for powder material. The rectification was interpreted to be mainly caused by the depletion layer formed near the crystal surface due to the oxygen chemisorption on the crystal surface.
Properties of Y5V Multilayer Ceramic Capacitors with Nickel Electrodes
Authors: Shizuno Hisamitsu , Kusumi Shinya , Hiroshi Saito Hiroshi Saito , Hiroshi Kishi Hiroshi Kishi
Published: February 2005

In order to realize nickel electrode multilayer ceramic capacitors with high capacitance per volume, the holmium-doped (Ba, Ca, Mg)(Ti, Zr)O3 system was studied. In the case of maintaining an oxidizing atmosphere at the cooling stage, the resistivities of the dielectric materials were easily recovered by doping with Ho. The newly developed dielectric material exhibited high dielectric constant (18,000) and high resistivity (>10-12 Ω cm). Using the dielectrics, nickel electrode multilayer ceramic capacitors with high specific capacitance (Y5V 4.7 µF in EIA 1206 size) were developed. They showed highly reliable characteristics.
Determination of the Interface Trap Density in Metal Oxide Semiconductor Field-Effect Transistor through Subthreshold Slope Measurement
Authors: Lyu Jong-Son , Lee Kee-Soo Nam
Published: February 2005

Interface trap densities at gate oxide/silicon substrate (SiO2/Si) interfaces of metal oxide semiconductor field-effect transistors (MOSFETs) were determined measuring the substrate bias dependence of the subthreshold slope. This method enables the characterization of interface traps residing between the midgap and strong inversion (2 times the Fermi potential) of small MOSFETs. In consequence of the high accuracy of this method, the energy dependence of the interface trap density is more reliable. The application of this technique to a MOSFET showed good agreement with the result obtained through the high-frequency/quasi-static capacitance-voltage (C-V) technique for a MOS capacitor. Furthermore, substrate dopant concentration obtained as a by-product through this technique also showed good agreement with the result obtained through the body effect measurement.
Composition and Growth Mechanisms of a Boron Layer Formed Using the Molecular Layer Doping Process
Authors: Saitoh Naoto , Akamine Tadao , Kenji Aoki Kenji Aoki , Yoshikazu Kojima Yoshikazu Kojima
Published: February 2005

A new doping process, molecular layer doping (MLD), allows for formation of extremely shallow junctions. We have studied the composition and growth mechanisms of boron layers formed on a Si substrate through the MLD process using diborane as the boron feed gas. At temperatures below 600°C, a pure boron layer is formed through the deposit of boron generated through thermal decomposition of diborane. At temperatures over 700°C, the boron layer contained silicon. At 800°C, a boron silicide layer is formed through reaction of boron with the silicon in the substrate. The growth rate of a boron silicide layer depends on the orientation of the Si substrate. However, that of a pure boron layer does not depend on the orientation. The composition of the layer after annealing at 900°C was analyzed using the RBS method and was found to be SiB6. Results of MLD processes on several kinds of underlying layers (e.g., SiO2, Si3N4, poly-Si) are also presented.
Annealing of Se+-Implanted GaAs Encapsulated with As-Doped a-Si:H
Authors: Yokota Katsuhiro , Nishida Kouji , Yutani Akira , Tamura Susumu , Horino Yuuji , Chayahara Akiyoshi , Satho Mamoru , Hirai Kiyohito , Takano Hiromichi , Kumagaya Mashao
Published: February 2005

The surface of 100 keV Se+-implanted GaAs was encapsulated with As-doped a-Si:H with a thickness of about 80 nm. The sheet carrier concentration in thermally annealed samples increased with an increase in the concentration of As atoms in the a-Si:H encapsulant. A high sheet carrier concentration of 0.65×1014 cm-2 can be achieved on GaAs which was implanted with a dose of 3.3×1014 cm-2 and annealed at 1000°C for 15 min after encapsulation with an As-doped a-Si:H film. Furthermore, the diffusion rate of the implanted Se atoms was reduced with an increase in the concentration of As atoms in the encapsulant.
Metalorganic Molecular Beam Epitaxy of AlGaAs Using APAH
Authors: König Frank , Mörsch Georg , Kamp Markus , Lüth Hans , Hostalek Martin , Pohl Ludwig
Published: February 2005

To take advantage of the benefits of gaseous precursors for the growth of AlGaAs, a reduction of the carbon and oxygen uptake from the sources is necessary. Therefore, new precursors have been developed recently to overcome these problems. An entirely new approach is the use of an intramolecular saturated precursor, where the coordinative saturation against oxygen is realised by means of a double ring structure. 1-(3-dimethylaminopropyl)-1-ala-cyclohexan (APAH) is a representative of this class of precursors. In metalorganic molecular beam epitaxy (MOMBE) the suitability of APAH for the growth of Al
x
Ga1-x
As layers (0≤x≤1) was investigated in combination with TEGa and arsine. For the grown layers morphology and crystallinity are found to be excellent, whereas the background carrier concentrations are in the range of p=1017 to 1019 cm-3. SIMS measurements clearly identify carbon as the main acceptor. Other than carbon, nitrogen is also incorporated from APAH. Despite this, APAH is useful for particular heterostructure applications as demonstrated by quantum well structures with excellent interfaces. Therefore, in MOMBE of AlGaAs, APAH is a suitable Al precursor for applications where p-type doping of 1017 cm-3 or above is required or acceptable (e.g., in HBT).
Accurate Measurement of Layer Thickness Using Optical Reflective Spectra of Bragg Mirrors Grown by Molecular Beam Epitaxy
Authors: Toyoda Takashi , Mitsunaga Kazumasa , Jun Ohta Jun Ohta , Kazuo Kyuma Kazuo Kyuma
Published: February 2005

We propose a new method for accurate measurement of layer thicknesses using the optical reflective spectra of Bragg mirrors in the GaAs/AlGaAs/AlAs material system. Two mirrors that have different central wavelengths were prepared in order to obtain more accurate thickness measurements of layers, for example, GaAs and AlAs epitaxial layers, which were components of the Bragg mirrors. As a result, we measured layer thicknesses accurate to within around ±1%.
Experimental Studies on the Electronic Structure of Pb1-xEuxTe
Authors: Iida Masayuki , Shimizu Takanori , Enomoto Hiroyuki , Hajime Ozaki Hajime Ozaki
Published: February 2005

P- and n-type Pb1-x
Eu
x
Te (0≤x≤0.25) single-crystal films were prepared on BaF2 (111) substrates using the hot-wall epitaxy technique. The lattice constant increases nonlinearly with the composition ratio x, and the energy gap increases rapidly up to x=0.07, while its rate of increase decelerates for x>0.07. X-ray photoelectron spectroscopy measurements revealed that the localized Eu 4f level centers around 1.2-1.5 eV below the valence band maximum. It is seen from the transport measurements that all of the n-type films are metallic but for the p-type films a metal-to-insulator transition takes place at x=0.07. Using these results, the electronic structure of Pb1-x
Eu
x
Te is proposed in which the Eu 4f localized electron plays an important role in the electronic properties for intermediate composition ratio (x>0.07).
Demonstration of Lateral p-n Subband Junctions in Si Delta-Doped Quantum Wells on (111)A Patterned Substrates
Authors: Yamamoto Teiji , Inai Makoto , Hosoda Makoto , Toshihiko Takebe Toshihiko Takebe , Toshihide Watanabe Toshihide Watanabe
Published: February 2005

The lateral subband p-n junction (LSJ) is demonstrated through a Si delta-doped GaAs/AlGaAs multiple quantum well (MQW) structure on patterned (111)A GaAs substrates. The optical properties of the MQW on a (311)A sloped surface and a (111)A flat surface are evaluated by cathodoluminescence. We confirm the subband formation and lateral p-n junctions for Si delta-doped MQWs. The LSJ shows good current-voltage properties when forward currents are injected into it. A recombination emission (791 nm) with an energy level higher than the band gap of bulk GaAs is observed at 300 K; this clearly shows that the potential bending occurs between n-type subbands and p-type subbands. The rise time of light-emitting diodes (LED) with the LSJ (LSJ-LED) is below 5 ns (>200 MHz). The LSJ has a high potential for applications in optical devices.