bluuebunny/crossref_metadata_2025 huggingface dataset:
Oriented Crystal Growth of Si on SiO2 Patterns by Pulse Ruby Laser Annealing
Authors: Tamura Masao , Tamura Hiroshi , Miyao Masanobu , Tokuyama Takashi
Published: March 2014

Poly-Si films 200–600 nm thick deposited on (100) Si substrates having SiO2 stripe patterns have been transformed by Q-switched pulse ruby laser irradiation with energy densities between 1.0 and 2.0 J/cm2 into single crystals on the SiO2 patterns as well as on the Si. The regrowth of poly-Si on SiO2 starts laterally from regrown poly-Si on Si just after or during the vertical growth of poly-Si on Si by liquid phase epitaxy. Such lateral growth of poly-Si on SiO2 makes single crystal Si film formation possible on entire SiO2 patterns up to 4 µm wide under appropriate laser power and poly-Si thickness conditions. However, straight stacking faults in the <311> direction remain in Si films grown on SiO2, although dislocations generated in the Si regrown on Si escape to the sample surface along the inclined plane of the SiO2 window edges.
Formation of a Double-Hetero Si/CoSi2/Si Structure Using Molecular Beam and Solid Phase Epitaxies
Authors: Saitoh Shuichi , Ishiwara Hiroshi , Furukawa Seijiro
Published: March 2014

Hetero- and homostructures of Si/silicide, Si/Si and Si/silicide/Si are formed using molecular beam epitaxy (MBE) and solid phase epitaxy (SPE). Optimum conditions for forming the double heterostructure are discussed based on such experimental results that single crystalline NiSi2, CoSi2 and Pd2Si films are formed on (111)Si substrates but not on (100) or (110)Si. From ion channeling and backscattering measurements, it has been shown that good Si films containing no Co atoms can be epitaxially grown on the Si(111)/CoSi2 structure by MBE at temperatures around 500 °C or by SPE at temperatures around 1000 °C. It has also been shown that NiSi2 is inadequate as an intermediate silicide in the double heteroepitaxy, since a large amount of Ni atoms in the Si(111)/NiSi2 structure moves to the surface during Si deposition in MBE.
A New Self-Aligned Framed Mask Method for Selective Oxidation
Authors: Minegishi Kazushige , Imai Kazuo , Kiuchi Kazuhide , Hirata Kazuo , Yoriume Yutaka
Published: March 2014

A new selective oxidation method, which realizes fine isolation width for MOS LSIs, has been developed. The oxidation mask in this method has a Si3N4 frame formed at a perimeter of a conventional mask pattern by self-aligned technique. This technique is composed of deposition step of Si3N4 film to cover the conventional mask and dry etching step of this film to form the frame without a photoresist pattern. Bird's beak extent is suppressed to less than 300 nm. Dislocation generation in silicon substrate is also suppressed in this framed mask method. Bird's beak suppression brings about extention in an effective device area and realizes a transistor with effective channel width 1.0 µm wider than that in the conventional mask method. The p-n junction prepared by this new method exhibits as small leakage current as that by the conventional method.
Negative Patterning of AZ1350J by Electron-Beam Desensitization of Photo-Sensitive Compound
Authors: Mochiji Kōzō , Maruyama Yōji , Murai Fumio , Okazaki Shinji , Takeda Yutaka , Asai Shōjirō
Published: March 2014

The discovery of a unique property of AZ1350J photoresist under electron-beam exposure and its successful application to negative patterning of AZ1350J are reported. It is found that an electron-beam desensitizes AZ1350J to the succeeding UV-light exposure and makes the resist insoluble to basic developers. This new mechanism, named ELDER (ELectron-beam DEsensitization of photoResist), is used to obtain negative resist images of AZ1350J. These images have a very high resolution down to 0.75 µm lines and spaces, as well as excellent dry-etch resistance. Aluminum wiring patterns of MOS LSIs are successfully dry-etched with a mask of negative AZ1350J images. The ELDER process technology should prove useful for electron-beam direct fabrication in the submicron range.
High Resolution Fabrication of Submicron Structures by Ion Beam Lithography
Authors: Moriwaki Kazuyuki , Aritome Hiroaki , Namba Susumu
Published: March 2014

Ion beam lithography formicro fabrication in submicrometer or smaller dimension is studied. PMMA and FPM resist are used to be exposed by 50keV H+ beam. Sensitivity and γ value of PMMA for a developer of MIBK: IPA=1 : 3 are 2×10-6 C/cm2 and 3.3, respectively. By using Au pattern-mask without substrate, fine structure (less than 0.1 µm) at the pattern edge is replicated in PMMA resist accurately. Backscattering effect is found not to affect the high resolution of ion beam lithography unlike in electron beam lithography. These features show ion beam lithography as a very useful technique for submicron pattern fabrication.
(Invited) Heterostructures for Everything: Device Principle of the 1980's?
Authors: Kroemer Herbert
Published: March 2014

One of the dominant themes of semiconductor device R & D during the 1980's will be the incorporation of heterostructures into most existing kinds of devices, and the emergence of new kinds of devices made possible by heterostructures. In this paper the power of heterostructures as a design tool is illustrated by discussing several ways in which the incorporation of heterostructures can improve the bipolar transistor. The dominant idea is that energy gap variations are a powerful way to control carrier flow; in bipolar structures they permit the control of electrons and holes independently. Several applications of this principle are discussed, going beyond the familiar wide-gap emitter concept, and including several concepts not previously discussed in the literature. The paper closes with a brief discussion of non-bipolar applications and speculative future applications.
An Analysis of EBIC Response of ITO/poly-Si Solar Cells
Authors: Inoue Narumi , Miyakawa Toru , Wilmsent Carl W.
Published: March 2014

An EBIC technique is applied to the grain boundaries of an ITO/poly-Si solar cell in order to investigate the effect of grain boundaries on solar cell output. The results are well explained by solving a three dimensional diffusion equation. It is found that the regions with reduced EBIC signals around the grain boundaries are much smaller than the bulk diffusion length. The difference between the EBIC profile and that of local cell photoresponse is pointed out and a way to estimate the latter is proposed based on the information gained from the EBIC profile.
Rapid Characterization of Solar Cell Performances
Authors: Takakura Hideyuki , Nishino Taneo , Hamakawa Yoshihiro
Published: March 2014

A new technique of computer-assisted automated measurements and analyses for solar cell output characteristics has been developed. A curve fitting method developed in this work permits the estimation of solar cell parameters such as the saturation current, n value, etc. A quantitative correlation between these parameters and fabrication conditions is discussed. This automated system also enables us to calculate the real photocurrent from the output characteristics and more precise analyses about the solar cell output parameters are discussed.
Dependence of RF Power on the Content and Configuration of Hydrogen in Amorphous Hydrogenated Silicon by Reactive Sputtering
Authors: Imura Takeshi , Ushita Katsumi , Mogi Kazuhisa , Hiraki Akio
Published: March 2014

Infrared absorption spectra at stretching bands of Si–H were investigated in hydrogenated amorphous silicon fabricated by reactive sputtering in the atmosphere of Ar and H2 (10 mole%) at various input rf powers in the range from 0.8 to 3.8 W/cm2. Hydrogen content mainly due to the configuration of Si=H2 in the film increased with the decreasing rf power, as the deposition rate was decreased. On the other hand, the quantity of the monohydride (Si–H) configuration depended less on the power. Attachment of hydrogen molecules onto the fresh and reactive surface of silicon deposited successively was proposed for possible process of hydrogen incusion into amorphous silicon resulting in Si=H2 configuration. The photoconductivity increased as the input power became higher, when the deposition rate also increased linearly with the power.
Characteristics of Schottky Barrier Diodes in Reactively Sputtered Amorphous Si:H
Authors: Okushi Hideyo , Nakagawa Katumi , Yamasaki Satoshi , Yamamoto Hideo , Matsuda Akihisa , Matsumura Mitsuo , Tanaka Kazunobu , Iizima Sigeru
Published: March 2014

We report a systematic study of Schottky barrier diodes in the reactively-sputtered amorphous Si:H films where we attempt to understand a diode characteristic on the basis of film properties such as bonded H content, optical gap, activation energy of conductivity, spin density and dark- and photoconductivity.
The I-V and C-V characteristics are strongly dependent on the bonded H content, suggesting that the effective density of gap states considerably decreases with increasing H content in a-Si:H film. This result is consistent with the independent ESR study of the properties of the film itself.
Optimizations of the Film Deposition Parameters for the Hydrogenated Amorphous Silicon Solar Cell
Authors: Tawada Yoshihisa , Yamaguchi Takeshi , Nonomura Shuichi , Hotta Sadayoshi , Okamoto Hiroaki , Hamakawa Yoshihiro
Published: March 2014

Optimization of the photovoltaic performance in the plasma deposited a-Si:H heteroface p-i-n junction solar cells has been experimentally studied. A series of systematic experiments on the relation between photovoltaic performances and substrate-positive column distance with several power density have been carried out. As the results, a-Si:H solar cell fabrication technology realizing a conversion efficiency of higher than 5.5% under AM-1 sun light has been developed with a considerably good reproduceablity. Moreover, it has been demonstrated that a conversion efficiency exceeding 6.1% is obtained in designing of an optimized i-layer sandwitched with a wide band gap a-SiC:H front p-layer and a low resistivity n-type back electrode.
Broadening of Spectral Response Width by a-Si/a-SiGe p-i-n type Solar Cells
Authors: Nakamura Genshiro , Sato Kazuhiko , Yukimoto Yoshinori , Shirahata Kiyoshi
Published: March 2014

We report the MIS type a-Si:H solar cells, plasma analysis using quadrupole mass analyzer and tandem type solar cell which improved spectral response in the long wavelength region.
MIS type a-Si:H solar cells inserting TiO
x
layer as an insulator show the conversion efficiency of 4.4%. The improvement of the collection efficiency in the short wavelength region were accomplished by decrease in interface state density with addition of TiO
x
film. Plasma polymerized species, (SiH
m

+)2, increased with the rf power up to 40–50 W and decreased as a result of the decomposition to (SiH
m

+) species, but in the case of GeH4 reaction, (GeH
m

+)2 species decreased monotonously with rf power. Suitable condition of a-SiGe:H films deposition are related to the behavior of the polymerization and decomposition of SiH4 and GeH4 gases, and high quality films are obtained at relatively low rf power condition before (GeH
m

+)2 decomposition. Tandem type amorphous solar cell shows 3.2% coversion efficiency and the collection efficiency in the long wavelength region are clearly improved.
Characterization of 3-Inch Solar Cells Fabricated from Granular Silicon Obtained in a Fluidized-Bed Reactor
Authors: Warabisako Terunori , Matsubara Sunao , Itoh Haruo , Saitoh Tadashi , Tokuyama Takashi , Matsukuma Kunihiro , Hasegawa Niichiro
Published: March 2014

Industrial feasibility of a solar-grade silicon material for use in terrestrial solar cells is demonstrated through the fabrication of practical size, 3'' diameter, solar cells. The granular silicon prepared in a fluidized-bed reactor consumes less energy than the current Siemens process. A polycrystalline ingot obtained by the Czochralski method is described as a function of ingot length in terms of electrical properties and solar cell performance. Impurity gettering is also attempted through the application of a phosphorus diffusion process. The possibility of realizing a conversion efficiency higher than 8% for an entire ingot is revealed.
A Large Active Area Be–Si MIS Solar Cell with Textured Surface
Authors: Maeda Yasuhiro
Published: March 2014

Be–Si MIS solar cell with a textured surface of 2 cm×2 cm has been developed. In basic investigations of Be–Si MIS cell, it was found that Be has a highly barrier height for p-type silicon and the cell efficiency using flat plated surface of silicon is 8.5% for a 1.1 cm2 active area cell. In the fabrication techniques, Be was deposited onto the textured surface of silicon for forming a Schottky barrier by electron beam source. In this case, Si wafers were placed in a vacuum system with the angle of incidence formed by the textured surface and the Be vapor stream. To prevent leakage at textured surface, the double layered front grid electrode consisting of barrier metal and alminium contact was accomplished. Typical cell having an active area of 3.62 cm2 exhibits V
oc=0.51 V, I
sc=27.6 mA/cm2, FF=0.52 and an AMI efficiency of 7.2%.
Measuring Methods of Solar Cell Parameters Using Spectrum Response of Short-Circuit Current
Authors: Warashina Masatoshi , Ushirokawa Akio
Published: March 2014

Using the spectrum response in which a photon flux F is required to produce the short-circuit current to be constant, new methods for the determination of the solar cell parameters, i.e. the ratio (D
p/S
p) of the diffusion coefficient D
p of minority carriers in the n-type top region to the surface recombination velocity S
p at the front surface, the junction depth x
j, the reflectivity R and the diffusion length L
n of minority carriers in the p-type base region, are proposed. It is obtained that L
n has a tendency to decrease with increasing the doping level and that R of black cells has a tendency to decrease with etching time. It is found experimentally that D
p/S
p of flat-surface cells and of black cells has a tendency to increase with doping level and with etching time, respectively.
Photoluminescence Characterization of Polycrystalline Si for Solar Cells
Authors: Nishino Taneo , Nakayama Hiroshi , Takakura Hideyuki , Hamakawa Yoshihiro
Published: March 2014

The photoluminescence technique has been applied to the characterization of polycrystalline silicon for solar-cell applications in order to test its diagnostic potential to the material. It is shown that this simple and contactless technique can provide information about the spatial variation of the minority-carrier diffusion length which is a useful figure of merit of a solar-cell material. Furthermore, we report a characteristic behavior of the PL intensity in polycrystalline silicon that the PL intensity reduces gradually with time and does not return to the initial PL intensity even if the excitation light turns off and on again.
A Monolithic GaAs Solar Cell Array
Authors: Masu Kazuya , Ying-Shu Quan , Konagai Makoto , Takahashi Kiyoshi
Published: March 2014

Series-connected multi-junction solar cells have a number of important advantages over single junction cells because of the high open circuit voltage, e.g., the reduction of the series resistance effects in the context of system design and the suitability to the consumer electronic photo-cells. The Schottky barrier type and p-n homojunction type monolithic GaAs solar cell arrays were fabricated on (100) Cr-doped semi-insulating GaAs wafer with 5 µm n-GaAs epitaxial layer by using the usual photolithographic technique. The solar cell arrays exhibit V
oc=3.0 V, η=7.5% for the 5 adjacent Schottky barrier type cell array and V
oc=3.2 V, η=8.4% for the 4 adjacent p-n homojunction type cell array under simulated AM1 insolation, respectively.
Finite Element Analysis of Flexural Transducer Using Shear Mode Piezoelectric Ceramics
Authors: Tomikawa Yoshiro , Konno Masashi , Gounji Takashi , Takeuchi Chikao
Published: March 2014

A finite element method employing three-dimensional solid elements applicable to vibration systems including piezoelectric materials is used to analyze the vibrational characteristics of a flexural transducer.
This transducer is composed of shear mode piezoelectric ceramics sandwiched by two pieces of elinver alloy, and is intended for use in a wide band mechanical filter. From information obtained by analysis, the equivalent circuit element such as equivalent inductance, equivalent capacitance and capacitance ratio can be determined. These calculated results are useful in designing a flexural transducer using shear mode piezoelectric ceramics.
SAW Propagation Characteristics on α-Quartz with Arbitrary Cut
Authors: Shimizu Yasutaka , Yamamoto Yasushi
Published: March 2014

New modified temperature coefficients of elastic stiffnesses for alpha-quartz were obtained for better agreement with experiments. Using these constants, SAW propagation characteristics on alpha-quartz were calculated, and the results are presented in a series of contour maps. From these maps, many new cuts of plate with zero temperature coefficient were found and theoretical and experimental studies were conducted on one of them which had a more stable temperature dependence than the ST-cut.
Preparation and Application of ZnO Thin Film by Cylindrical Magnetron Sputter –ZnO Thin Film SAW Long Delay Line–
Authors: Setsune Kentaro , Tanaka Toshihide , Yamazaki Osamu , Wasa Kiyotaka
Published: March 2014

This report describes SAW long delay lines using ZnO thin film for a figh resolution TV camera. The delay lines are comprised of ZnO thin film/glass substrate structure. All interdigital electrodes are inserted between the ZnO thin film and the glass substrate. Delay length and wave length of the SAW are 57.5 mm and 15 µm, respectively. A large cylindrical magnetron sputtering is used for making the ZnO thin film. A suitable selection of glass substrate enabled excellent temperature stable operation. The present delay line shows delay time of 25 µs at ∼150 MHz and temperature stability of the delay time is less than 4 ppm/°C.
A New Hollow Cylindrical Ultrasonic Wave Radiator
Authors: Asai Kiyokazu , Takeuchi Akihiro
Published: March 2014

The design and performance of a new hollow cylindrical ultrasonic wave radiator which has a large vibratory surface are presented. The vibrating system is composed of a hollow cylinder connected to an ultrasonic horn that serves simultaneously as a mechanical resonant transmitter. The hollow cylindrical vibrator has a flexural vibration in a radial direction on all its extensive surface areas. Liquid supplied to the nodal lines of the flexural vibration is atomized on the outer or inner circumferential surface of the vibrating cylinder. A stable atomization of a large amount of liquid per unit time can be achieved.
Ultrasonic Power Accumulation by Use of Directional Converter
Authors: Itoh Katsuhiko , Mori Eiji
Published: March 2014

The authors have devised an original type of ultrasonic power accumulator using a directional converter which has a two-or three-dimensional coupling mode of vibration. We experimented with this ultrasonic power accumulator using an R-L type directional converter. We then conducted experiments to determine the accumulation characteristics of ultrasonic power. We have confirmed that this ultrasonic power accumulator can produce a large quantity of ultrasonic power by summarizing the output power of several transducers.
Numerical Simulation of Acoustic Emission
Authors: Onoe Morio , Tsao Jing Wen
Published: March 2014

Acoustic Emission (AE) is useful for a real time monitoring of deformation and fracture processes in solid. For full utilization of the information contained in the wave form observed by an AE sensor placed on the surface, it is essential to understand transient wave propagation from a source to a sensor. Since the theoretical analysis is complicated, numerical simulation based on the finite difference method is developed. An intelligent microprocessor system is used for processing, TSS communication, display and tablet input. Several numerical examples of axisymmetric AE waves in a plate are shown.
A New Ultrasonic Flaw Detection Method on Smooth Surfaces and its Applications
Authors: Otani Takahiko , Urabe Yasumasa
Published: March 2014

A new method of surface defect inspection is described which uses a continuous ultrasonic sound with a wide beam to eliminate the weak point of conventional acoustical or optical methods using a sharp scanning beam. Advantages of the new method are that it is less influenced by surface unevenness, and is less sensitive to disturbances such as fluctuation of acoustic medium and mechanical vibrations of inspected surfaces. The above characteristics are indispensable for inspection of ceramic surfaces such as glazed tiles which are smooth but lacking in flatness.
Wide Frequency Range Miniature Hydrophone for the Measurement of Pulse Ultrasonic Field
Authors: Ide Masao , Ohdaira Etsuzo
Published: March 2014

Ultrasonic diagnostic equipment utilizing the pulse reflection method is widely used in the field of medicine. For evaluation of the equipment and for studies on bioeffects of ultrasound, it is necessary to know the sound field generated by the equipment. This paper reports on wide frequency range miniature hydrophones for the measurements of pulse ultrasonic fields of several MHz range. Construction of the developed hydrophones, experimental data on their performance and measured results of sound fields obtained by the hydrophones are presented.
Electronic Scanning Ultrasonic Diagnostic Equipment
Authors: Kasai Chihiro , Yoshikawa Yoshihiro
Published: March 2014

Recently ultrasonic diagnostic equipment has been widely used in the medical field for the visualization of soft tissue. In this paper the principles of an electronic scanning device, which is the most widely used type of ultrasonic diagnostic equipment, are described.
Measurement of Acoustic Velocity and Acoustic Attenuation Constant Distribution in Soft Tissue by Ultrasonic CT
Authors: Itoh Takashi , Tamura Kiyoshi , Choi Jong-soo , Matsubara Shinichi , Nakajima Masato , Yuta Shinichi
Published: March 2014

An experimental data acquisition system for ultrasonic CT is developed. The system displays cross-sectional images representing acoustic velocity distribution and acoustic attenuation constant distribution within a subject. Experiments using a sponge phantom and animal tissues are performed. The attenuation images show high values on the borders of objects because of the wave characteristics such as reflection and refraction of ultrasound.
High Resolution Imaging Method Using Ultrasonic Impulsive Sound
Authors: Okujima Motoyoshi , Endoh Nobuyuki
Published: March 2014

In the pulse-echo method, it is difficult to obtain high resolution in lateral and range directions simultaneously. We have developed a high resolution imaging method using impulsive sound.
In this method, a very short sound pulse is projected from an electromagnetic induction type transmitter, reflection signals received by a PVDF array transducer are stored in a digital memory system and an image is reconstructed by a computer. It was confirmed in computer simulation that both the lateral and range resolutions are of 1.5 wave-lengths. Experiments were carried out in a water bath, and a clear image of two steel balls was obtained.
Observation of Underwater Ultrasound Propagation in the Sea by Two-Period M-Sequence Signal Method
Authors: Okujima Motoyoshi , Ohtsuki Shigeo
Published: March 2014

The velocity of a current going in and out through a strait can be measured by the differences in underwater sound propagation times with and against the current. However, ambient pulsive noises often interfere with the measurements of sound propagation times when a pulsed sound is used. A two-period M-sequence signal method is therefore proposed which is free from ambient pulsive noises. A sound propagation test was carried out. Short term propagation stability and tidal effects on multipath propagation were observed.
Acoustic Studies in Liquid Helium
Authors: Ikushima Akira , Fujii Itsuhiro , Kaneko Kazuyuki , Nara Koichi , Okamoto Kohji , Tozaki Ken-ichi
Published: March 2014

Two acoustic studies in liquid helium recently carried out in the present group are reported. The first of these is the study of critical sound attenuation and dispersion associated with the critical phenomena near the super fluid transition temperature, where the validities of the dynamic scaling hypothesis and the universality precept are claimed. The second one is the study of dynamic properties of normal liquid 3He, a typical Fermi liquid, by the use of sound attenuation. A Landau parameter F
2 and the lifetime of 3He quasiparticles have been obtained as functions of pressure.
Application of Finite Element Method to Acoustic Guidedwave Problems
Authors: Koshiba Masanori , Okada Masaya , Morita Hikaru , Suzuki Michio
Published: March 2014

The finite element method has been applied to two acoustic guidedwave problems. One is the propagation problem of two-dimensional piezoelectric waveguides with semi-infinite media, and the second is the discontinuity problem of SH-type modes in a piezoelectric plate of crystal symmetry 6 m
m. In these problems, acoustic fields extend infinitely, so that the approach is a combination of the finite element method and the analytical method. The former is used for the interior region, while the latter is utilized for the exterior region.
Brillouin Scattering in Layered Semiconductors using Microprocessor-controlled Fabry-Perot Interferometer
Authors: Shimizu Haruo , Yamada Masayoshi , Maegawa Shigeto , Yamamoto Keiichi , Abe Kenji
Published: March 2014

A microprocessor-controlled multipassed Fabry-Perot interferometer has been developed for high-resolution and high-contrast Brillouin scattering spectroscopy. Using this interferometer, Brillouin scattering experiments have been carried out for GaSe1-x
S
x
mixed crystals having layered structures. Specific features of Brillouin scattering in the layered crystals were presented. Anomalous discontinuities of elastic constants of C
44 and C
33, related to the shearing and stretching force constants, have been found at the compositional ratios x≃0 and x≃0.4, which are related to the ε-γ and γ-β polytype transformations.
Acoustic Domain Injection Method and Resonant Brillouin Scattering
Authors: Itoh Yasuo , Hamaguchi Chihiro
Published: March 2014

Acoustoelectric domains consisting of high intensity ultrasonic waves with wide frequency components of 0.1 to 4 GHz are amplified in semiconducting CdS and injected to other semiconductors. The transmission efficiency was found to be 5–90% depending upon the frequency. By making use of the acoustic domain injection method, we measured some acoustic properties: acoustic domain transmission efficiency and attenuation coefficient. Further, we investigated the resonant Brillouin scattering of various semiconductors and determined the spectral dependence of the Brillouin scattering cross sections near the fundamental absorption edge.
Thickness Dependence of Photoacoustic Spectra in High-Resistivity GaAs
Authors: Tokumoto Hiroshi , Tokumoto Madoka , Ishiguro Takehiko
Published: March 2014

Photoacoustic (PA) spectra of high-resistivity GaAs with and without damaged surface layers are presented, emphasizing their sample thickness dependence. When the thickness was reduced below the thermal diffusion length, PA signals increased remarkably provided the absorption coefficient was larger than 10 cm-1. The signals below the fundamental absorption edge were strongly enhanced by the absorption due to damaged layers. An interpretation of the overall results of the experiment indicates a possible application of the PA technique to characterization of solid samples.
Impulsive Sound Sources Using Electric Discharge
Authors: Takeda Masayuki , Otani Takahiko
Published: March 2014

Sound sources using electric discharge to radiate a short impulsive spherical sound are described. Experimental results show that a very narrow space between two electrodes provides a spherical wave front and can be regarded as a point source. Radiated waveforms depend on the discharge parameters, and simple sound waveforms such as one period of sine or squared cosine are approximately obtained. Impulsive sounds generated by electric breakdown (electric discharge) at a focus of high intensity laser beam are also investigated.
Laser Probe for Surface Acoustic Wave Measurements
Authors: Yoneda Katsumi , Tawata Masahiro , Hattori Shuzo
Published: March 2014

Laser probe for the field measurements of surface acoustic waves (SAW) is performed using an optical interferometer with a He–Ne laser. This laser probe is composed of two optical paths named “twin path” disposed so closely and symmetrically with each other that the measurements are not disturbed by acoustic noise, low frequency ambient vibration, atmospheric fluctuation or room temperature change. A minimum detectable amplitude of 3×10-4 Å was attained by this laser probe in measurement of the vibration amplitude of quartz plate with final noise band width of 0.017 Hz.16)The operation and design of a twin path interferometer, the amplitude and the energy profile of SAW are described.
Generation and Applications of High Intensity Ultrasonics
Authors: Mori Eiji
Published: March 2014

Ultrasonics can be said to have become a subject for scientific study from the time of Langevin's invention of the quartz transducer in 1918. But the peaceful utilization of ultrasonics was initiated after the end of the Second World War in 1945. In this paper, we will outline the special characteristics, generation, transmission, radiation and applications of high power ultrasonics which can be expected on the alterations in substances or properties of matter.
Scanning Acoustic Microscope Employing Concave Ultrasonic Transducers
Authors: Chubachi Noriyoshi , Kushibiki Jun-ichi , Sannomiya Toshio
Published: March 2014

A mechanically scanned acoustic microscope (SAM) has been developed by Quate et al. with acoustic lenses for focusing acoustic waves. Recently, as an alternative system, a SAM with concave transducers has been proposed by the present authors. In this paper, the structure and characteristics of concave transducers are described, and some experiments on the SAM constructed with the concave transducers are performed at frequencies around 200 MHz. A combination system of plane and concave transducers is further developed to be applicable for acoustic velocity measurements in thin materials.
Surface-Acoustic-Wave Filters with Phase-Weighted Transducers for the Output Circuit of a Consumer VTR
Authors: Hirabayashi Makoto , Komatsu Yasutoshi , Kanamaru Masaji
Published: March 2014

A SAW filter for a consumer VTR has been developed. The filter consists of a uniform transducer and a transducer with half-wavelength spaces between the central part and the peripheral parts. The amplitude-frequency response is flat in the passband, since the SAW phase generated by the central part is opposed to that generated by the peripheral parts. The filters for the first and second TV channels were made on a common chip and mounted on a TO-5 package. Center frequencies of 93.4 MHz and 99.2 MHz, bandwidths of 4.5 MHz, insertion losses of 14 dB, in-band ripples of less than 0.8 dB, and out-of-band rejections of more than 14 dB were obtained.
Fabrication of Porous PTCR Thermistors and Their PTCR Effects
Authors: Kuwabara Makoto
Published: March 2014

Semiconducting barium titanate ceramics (referred to as PTCR thermistors) with a porosity in the range of 7 to 40% have been made to examine in detail the microstructural influence on the PTCR effect. The porous PTCR thermistors were prepared using barium titanyl oxalate as a starting material and Sb2O3 as a dopant, and they exhibited PTCR effects of more than 7 orders of magnitude. The PTCR effect in the porous materials was found to be very sensitive to microstructure.
Low Temperature Sintered BaTiO3 Ceramics with Bi4Ti3O12 Added
Authors: Yamaoka Nobutatsu , Fukui Masami , Nakamura Hiroshi
Published: March 2014

Microstructures and electrical properties of BaTiO3 ceramics with Bi4Ti3O12 added were investigated. BaTiO3 powders were synthesized by calcining preliminarily at 1100°C to 1300°C. Heat-treating was examined at a temperature range from 1000°C to 1200°C. All samples fired above 1100°C have individually a saturated shrinkage. Apparent activation energies for the shrinkage processes were ab. 125 kcal/mol and ab. 114 kcal/mol for a sample of BaTiO3(H)–0.04Bi4Ti3O12 composition and that of BaTiO3(L)–0.04Bi4Ti3O12 composition, respectively. In a previous sample a dielectric constant of the Curie point near to 120°C changed markedly at a firing temperature between 1150°C and 1160°C.
LiTaO3 Substrate Fabrication and Characterization for Pyroelectric Sensors
Authors: Fukuta Katsuyoshi , Matsumura Sadao , Yasuami Sigeru , Hirano Hitoshi , Fukuda Tsuguo
Published: March 2014

Large z-axis LiTaO3 single crystals of 2.5'' in diameter were grown by CZ technique under low thermal gradient of about 20°C/cm near the liquid surface. Large z-cut wafers, thinner than 100 µm, were obtained with high yield. Crystal defects in the wafers, pyroelectric and thermal properties of the crystals were examined and discussed.
Piezoelectric Properties of Hot-Pressed Lead Titanate Zirconate Family Ceramics
Authors: Nishida Masamitsu , Kawashima Shunichiro , Ueda Ichiro , Ouchi Hiromu
Published: March 2014

Piezoelectric properties of hot-pressed Pb(Zn1/3Nb2/3)O3–Pb(Sn1/3Nb2/3)O3–PbTiO3–PbZrO3 quaternary ceramics are described. The ceramics exhibited high coupling coefficient and high dielectric constant. A small addition of MnO2 to the quaternary ceramics increased markedly mechanical quality factor (Q
M=1400), and coercive field (E
c=20 kV/cm). The ceramics made it possible to produce high frequency transducer for large strain and high output voltage.
(Pb, Ca) ((Co1/2W1/2), Ti)O3 Piezoelectric Ceramics and Their Applications
Authors: Yamashita Youhachi , Yokoyama Katsunori , Honda Hiroki , Takahashi Takashi
Published: March 2014

Piezoelectric properties in (Pb, Me) ((Co1/2W1/2), Ti)O3 ceramics (Me=Ba, Sr or Ca) containing small amounts of MnO and NiO have been investigated. These ceramics are characterized by high apparent density, small dielectric constant (about 200) and facility in poling procedure. Among the ceramics added with the alkaline earth metals, the Ca-modified ceramics show markedly excellent performance–large longitudinal coupling factors k
33=0.54, k
t=0.52, small transverse coupling factors k
31=0.027, K
p=0.043 and small temperature coefficients less than 5 ppm/°C of frequency constants for radial and thickness vibration modes.
Low Temperature Growth of SbSI Single Crystals
Authors: Ishikawa Kenji , Tomoda Waichi , Toyoda Koichi
Published: March 2014

Crystallization of SbSI from the vapour phase was investigated. By lowering the growth temperature about 50°C (growing zone: 300°C, source zone: 320°C) than usual method, we could obtain large crystals with mirror-like surfaces and without hollows. The largest surfaces observed on the as-grown crystals were usually characterized by (110) planes. These crystals are suitable for optical measurements such as optical absorption or Raman scattering.
1.6 GHz SH-Type Surface Acoustic Wave Filter
Authors: Nishikawa Tsutomu , Tani Atsushi , Takeuchi Chikao , Minowa Junichiro
Published: March 2014

Surface skimming bulk waves (SSBW) are considered to be suitable for high frequency applications because of their high phase velocity. We analyzed these waves taking into account electrical and mechanical loading effects of interdigital electrodes. Calculated and experimental results indicate that these waves should be treated as SH-type surface acoustic waves or Love waves.
A 1.6 GHz SH-type SAW timing filter was developed for optical fiber transmission systems. The insertion loss was less than 12 dB, loaded Q was more than 800 and good temperature stability was obtained.
Impurity Effect on the Structural Phase Transition in SrTiO3
Authors: Sakudo Tunetaro , Hasebe Kyoichi , Ishizuka Takeshi , Unoki Hiromi , Oka Kunihiko
Published: March 2014

Composition dependence of the antiferro-distortive phase transition temperature in SrTiO3 was measured by observing the step-wise elastic anomaly for solid solution systems where Sr or Ti were partially substituted with various other ions. The transition temperature T

a
was found to increase or decrease almost linearly with the substitution rate. The amount of shift Δ
T

a
was understood as due to the combined effect of both the lattice-cell-volume effect and the `chemical' effect. The latter effect seems to show the different tendency with regards to the location of the substituting ions either at the Si-site or at the Ti-site.
Electro-Optic Properties of FE/PC Sandwich Memory Device
Authors: Masuda Yoichiro , Baba Akira , Jyumonji Masanori , Kasai Kiyokazu
Published: March 2014

A FE/PC sandwich memory device was constracted using a transparent ceramic, a photoconductive CdS film and transparent NESA electrodes.
Electro-optic properties of the device were measured with light pulses under various measuring conditions such as various applied voltages, irradiation times and luminous intensities.
The light intensity stronger than 4000 lx was found to be neccessary to write signals onto the device.
Piezoelectric Pile
Authors: Yamashita Syuji
Published: March 2014

Attempt have been carried out to compose a displacing device of piled piezoelectric elements. Multiple number of piezoelectric ceramic plates were stacked in a composite. This device is capable of generating desired high level of displacement which has been hitherto unattainable. Some applications of such piles are proposed.
A New Photoluminescence Method of Characterizing the In-Depth Profile of Thermally Induced Defects in CZ–Si
Authors: Nakayama Hiroshi , Katsura Johji , Nishino Taneo , Hamakawa Yoshihiro
Published: March 2014

Room-temperature photoluminescence method to characterize quantitatively thermally induced defects in CZ–Si is proposed, with particular emphasis on the in-depth defect profile formed by the thermal oxidation and intrinsic-gettering treatment. Using a wafer cross-section scanning technique, the room-temperature photoluminescence-intensity profile of the wafer cross section has been measured as a function of depth from the irradiated wafer surface. On the basis of theoretical considerations on minority-carrier diffusion taking into account the recombination kinetics in the free-carrier and trapped-carrier system, the in-depth profile of a “differential diffusion length,” which is defined as a good measure of the defect density heterogeneously distributed, has been obtained from a simple analysis of the photoluminescence intensity profile.
Chemical and Physical Roles of Individual Reactive Ions in Si Dry Etching
Authors: Tachi Shin'ichi , Miyake Kiyoshi , Tokuyama Takashi
Published: March 2014

Chemical and physical sputtering yields of silicon by fluorocarbon ions such as F+, CF+, CF2
+, CF3
+ and C+ were investigated as a function of incident ion energy. Yield measurements over the 100–3000 eV incident ion energy range were performed through the use of mass-selected single species ion beam etching and in situ quartz crystal oscillator in an ultrahigh vacuum atmosphere. It was found that Si surface was fully covered with carboneous polymer and carbon in the cases of CF+ and C+ irradiation in the energy ranges of 100–700 eV and 100–2500 eV, respectively. Small quantity of carbon accumulation was also observed in the CF2
+ ion beam irradiation of silicon in the 100–200 eV region, on the other hand, no carbon accumulation took place for F+ and CF3
+ ion beam cases. In conventional Si dry etching by a CF4 gas plasma, since low energy (less than 1000 eV) fluorocarbon ions impinge the etched surface, it can be concluded that suppression of silicon etch rates mainly arises from the incidence of C+ and CF+ ion species.
(Invited) MBE-Grown GaAs/N–AlGaAs Heterostructures and Their Application to High Electron Mobility Transistors
Authors: Hiyamizu Satoshi , Mimura Takashi , Ishikawa Tomonori
Published: March 2014

Quasi-two-dimensional electron gas accumulating at the heterojunction interface in selectively doped GaAs/N–Al
x
Ga1-x
As (x=0.3) grown by MBE showed extremely high mobilities of 8720 cm2/V·s at 300 K, 122000 cm2/V·s at 77 K, 260000 cm2/V·s at 5 K and 396000 cm2/V·s at 5 K (under light exposure). The mobility attained at 5 K is the highest for MBE grown semiconductor materials.
An enhancement mode high electron mobility transistor (HEMT) with a short gate (L
G=2 µm), fabricated from the heterostructure material, exhibited transconductance as high as 193 mS/mm of gate width at 300 K and 409 mS/mm at 77K. Furthermore, a 27-stage ring oscillator using HEMTs with gate lengths of 1.7 µm showed propagation delays of 56.5 ps at 300 K (with 0.46 mW of power dissipation per gate) and 17.1 ps at 77 K (0.96 mW). Performance of these devices at 77 K, which is the best ever reported, indicates that the HEMT has great potential for application to high-speed, low power integrated circuits.
Recrystallization of Silicon Film on Nitride/Oxide Double Insulating Structure by CW Laser Irradiation
Authors: Nishimura Tadashi , Sakurai Hiromi , Nagao Shigeo , Isu Toshiro , Akasaka Youichi , Tsubouchi Natsuro
Published: March 2014

Double layer structure of thin nitride on thick oxide is used as an insulating material in order to get a good quality of silicon layer on insulator by laser recrystallization. This structure makes deposited polycrystalline silicon (polysilicon) more resistant to stripping off at high power laser irradiation and results in large grains of silicon layer with random crystal orientations. Laser scanning steps of 20 to 30 µm/step are obtained as optimum values for the largest grain size and smooth surface by investigation of grain growth and surface features. A fully oxide isolated bipolar transistor is fabricated in recrystallized silicon film on the substrate with the double insulating structure, and it shows following characteristics; typical values of h
FE, B
V
CBO, B
V
CEO, and B
V
EBO are 29, 73 V, 30 V and 5.2 V, respectively. This is the first demonstration of the bipolar transistor in silicon layer on insulator. Quite similar results in grain sizes after laser irradiation and electrical characteristics of transistors are obtained between two kinds ofpolysilicon by conventional LPCVD furnace and an epitaxial reactor at relatively high temperatures, while original grain sizes of the latter are apparently larger than that of the former.
Improvement of SOS Device Performance by Solid-Phase Epitaxy
Authors: Yoshii Toshio , Taguchi Shinji , Inoue Tomoyasu , Tango Hiroyuki
Published: March 2014

Crystalline quality in the whole region of silicon film on sapphire substrate has been improved by doubly applying solid-phase epitaxial regrowth combined with amorphization of both the silicon surface and the silicon-sapphire interface regions of SOS. Observations, by Rutherford backscattering and chemical delineation, indicate that planar defect density in the film becomes less than 1/100 of that in an as-grown film. Effective mobilities of n- and p-channel FETs in the improved film are 520 and 225 cm2/V·s, which are 1.3 times and 1.1 times larger than those in the as-grown film, respectively. A significantly reduced drain leakage current of 1.8×1012 A/50 µm for n-channel FET is obtained, whose value is about 1/100 of those in as-grown samples. The higher mobility and lower leakage current thus obtained, should be attributed to the drastic improvement of crystalline quality in the whole region of SOS by the double solid-phase epitaxy.
Formation of an Epitaxial Si/Insulator/Si Structure by Vacuum Deposition of CaF2 and Si
Authors: Asano Tanemasa , Ishiwara Hiroshi
Published: March 2014

Heteroepitaxial CaF2/Si and Si/CaF2/Si structures have been formed by conventional vacuum deposition of CaF2 and Si. Optimum conditions for obtaining good epitaxial films have been investigated by changing Si substrate orientations, film thicknesses, and substrate temperatures during film deposition. It has been found from Rutherford backscattering and channeling spectroscopy (RBS) that the crystalline quality of CaF2 films grown on Si (111) and (110) substrates is excellent, but that the quality of the films on Si (100) is much worse. It has also been found from RBS and TEM (transmission electron microscopy) that single-crystalline Si films are formed on the CaF2/Si (111) structure at substrate temperature of 700°C. Finally, etching characteristics ofCaF2 and Si films have been studied. It has been shown that the CaF2 and Si films are selectively etched by the wet and dry plasma processes.
Laser-Induced Lateral, Vertically-Seeded Epitaxial Regrowth of Deposited Si Films over Various SiO2 Patterns
Authors: Tamura Masao , Ohkura Makoto , Tokuyama Takashi
Published: March 2014

The difference in bridging epitaxy of Si over SiO2 by pulse ruby laser and cw-scanned Ar laser irradiation has been investigated using TEM and SEM. Pulse laser induced lateral regrowth over SiO2 is governed by uniform heat flow from the oxide window edges to the SiO2 center during a melting time of ∼100 ns. The regrowth length is limited to ∼2.5 µm and straight crystal boundary is formed in regrown layers when SiO2 stripe patterns are used. On the other hand, when cw-scanning laser is utilized, single crystal film is formed without crystal boundary over the whole 5 µm width oxide stripe pattern.
Process Characterization of MOS Devices by Scanning Electron Microscopy with 0.5–1 kV Electrons
Authors: Hashimoto Norikazu , Todokoro Hideo , Fukuhara Satoru , Senoo Kooji
Published: March 2014

A low acceleration voltage scanning electron microscope (SEM) is applied to the inprocess characterization of MOS LSI without any adverse effects. Radiation of electrons having an energy of less than 1 kV does not cause any MOS circuit characteristics to change, e.g., the V
th shift of a MOSFET is less than 0.01 V. A low voltage of 800 V is required to inspect resist patterns on SIO2–Si substrates to avoid charge-up effects.
An Amorphous Si High Speed Linear Image Sensor
Authors: Hamano Toshihisa , Ito Hisao , Nakamura Takeshi , Ozawa Takashi , Fuse Mario , Takenouchi Mutsuo
Published: March 2014

An amorphous silicon thin film linear image sensor of a sandwich structure has been developed. The sensor consists of a transparent ITO as an upper electrode, an a-Si: H layer and Cr or Al lower electrodes. The a-Si: H layer is formed by RF glow discharge. These layers are deposited on a glass or ceramic substrate.
The sensor has good photoelectric characteristics as follows: Photo-sensitivity is 10-7 A/cm2 1x, photo-response time is less than 0.5 ms and photo- to dark-current ratio is larger than 3×103.
The sensor can be operated by a -5 V single power source and this same power source can be used for the driving circuits.
A 1056-bit, 8 bit/mm linear image sensor has been fabricated. Using the device, images of a document have been read and reproduced successfully.
Amorphous Silicon Photoconductive Sensor
Authors: Kagawa Toshiaki , Matsumoto Nobuo , Kumabe Kenji
Published: March 2014

Photoconductive sensitivity and transient properties of non-doped and doped a-Si: H films were investigated. The non-exponential decays of photoconductivity were discussed using a dispersive diffusion limited recombination model. Doping effects on sensitivity and transient behaviors were also investigated. Phosphorus and boron dopings drastically reduced the pulsed light responsitivity. A photoconductive sensor array was fabricated and the performance was compared with that of CdS photosensors.