bluuebunny/crossref_metadata_2025 huggingface dataset:
Picosecond-Pulse-Pumped Distributed-Feedback Thick-Film Waveguide Blue Laser Using Fluorescent Brightener 135
Authors: Watanabe Hirofumi , So Hirotaka , Oki Yuji , Akine Shigehisa , Omatsu Takashige
Published: July 2010

We have demonstrated a distributed-feedback plastic waveguide blue laser using Fluorescent Brightener 135 pumped by a picosecond pulse laser. The optical properties of Fluorescent Brightener 135 and its laser properties including photostability were investigated. The experimental laser slope efficiency and energy threshold were 8.2% and 24 µJ, respectively. An operation lifetime of 5,000 shots was attained under a pump pulse energy of 28 µJ at a wavelength of 355 nm.
Origin of UV Sensitivity of SiON Film and Bidirectional UV Trimming of SiON Microring Resonator
Authors: Tatewaki Takashi , Kokubun Yasuo
Published: July 2010

We discovered a photoluminescence phenomenon of SiON waveguide by the UV irradiation and investigated the luminescence spectrum by a conventional microscope and diffraction grating spectroscopy. It was shown from these measurements that the defect created by UV irradiation causes the UV sensitivity of SiON film after thermal annealing. Next, we measured the spectrum change of a microring resonator with SiON core via single point long time UV irradiation and multi point UV irradiation. As a result, we demonstrated a selective UV trimming of microring resonator combining thermal annealing and multi point UV irradiation.
New Differential Phase Detection Method for Signal Waveform Modulation Multi-Level Discs
Authors: Yan Mingming , Pei Jing , Xu Haizheng , Pan Longfa
Published: July 2010

Signal waveform modulation multi-level (SWML) read-only discs employ sub-lands/sub-pits to achieve multi levels. However, the tracking error signal derived from the conventional differential phase detection (DPD) method deteriorates in the SWML read-only disc owing to sub-lands/sub-pits inserted in the conventional pits/lands. To solve this problem, a new DPD method, which employs a signal adjuster and a phase regenerator, is proposed. The experimental results show that the tracking error signal derived from the new DPD method has better characteristics of uniformity and signal-to-noise ratio than that derived from the conventional DPD method in the SWML read-only disc.
Synchrotron-Based X-ray Spectroscopic Investigation of Nitrogen-Doped Ge–Bi (8.4 at. %)–Te Thin Films during the Amorphous-to-Crystalline Structural Phase Transition
Authors: Kim Kihong , Jung M.-C. , Park  , Choi Sang Jun , Shin Hyun-Joon
Published: July 2010

Nitrogen-doped Ge–Bi (8.4 at. %)–Te thin films, which show a rapidly decreasing sheet resistance and NaCl-type X-ray diffraction peaks above 225 °C, were investigated by synchrotron-radiation-based high-resolution X-ray absorption spectroscopy (XAS) and photoelectron spectroscopy (XPS). As the as-deposited film transformed to the crystalline phase in an ultrahigh vacuum ambient, the N 1s and Bi 4f core levels chemically shifted towards higher binding energies (BEs), a lower-BE component developed at the Te 4d core level, and a higher-BE component developed at the Ge 3d core level. The nitrogen molecules, identified by the N K-edge absorption spectra, decreased in intensity and some of them were considered to have decomposed to form a N-content-increased quaternary system.
Modeling a Passively Q-Switched Nd:YVO4 Laser with an Application to Spatio-Temporal Instability
Authors: Wei Ming-Dar
Published: July 2010

In this study, a numerical model of a passively Q-switched laser system to concerning the transverse distribution of the optical field is presented. Applying this numerical model to examine the dynamics of a passively Q-switched Nd:YVO4 laser with a Cr4+-doped yttrium aluminum garnet (Cr4+:YAG) saturable absorber, a spatio-temporal instability is evident when this laser is operated in the transverse degenerate configuration. The mechanism of instability is mainly governed by the transverse mode competition among the degenerate modes. Results of this study demonstrate that there are two bifurcating branches corresponding to the different spatio-temporal evolutions as the pump power increases. Moreover, each bifurcation is accompanied by the excitation of the higher-order degenerate transverse modes.
Numerical Approach for Determination of Cutback Length to Estimate Dispersion and Loss Parameters of Terahertz Waveguides
Authors: Ishikawa Ken , Jr. Carlito Ponseca, , Estacio Elmer S. , Takatori Satoru , Sarukura Nobuhiko , Ishiguro Makio
Published: July 2010

We present a numerical scheme for the determination of the optimum fiber length in the cutback method to estimate the dispersion and loss parameters in terahertz waveguides. From a numerical simulation study and observations of the propagation of terahertz waves in wave guides, we found that the optimum fiber length giving the most accurate estimates of absorption and/or dispersion parameters obeys the empirical power law. We expect that the characterization of terahertz waveguides using this scheme will aid the precise control of the dispersion and loss parameters of waveguides in large volume fabrication.
Formation of Transparent SiO2 Protective Layer on Polycarbonate by 157 nm F2 Laser for Lightweight Automobile Window
Authors: Nojima Yoshihiko , Okoshi Masayuki , Nojiri Hidetoshi , Inoue Narumi
Published: July 2010

A transparent, hard silica glass (SiO2) layer was formed on a conventional protective coat made of silicone ([SiO(CH3)2]
n
) on a polycarbonate plate by the 157 nm F2 laser-induced photochemical modification of silicone into SiO2. An optimum laser irradiation time of the F2 laser was found to form a crack-free SiO2 layer. The high optical transparency of the samples in the visible light region remained unchanged after the F2 laser irradiation. In the Taber abrasion test, the SiO2 layer markedly reduced the number of scratches, resulting in a low haze value. The haze values of the samples also depend on the thickness of the silicone protective coat underneath the SiO2 protective layer. As a result, the difference of haze value (δHz) was successfully reduced to 3.6%, compared with these of the nonirradiated sample and a bare polycarbonate plate of approximately 11.3 and 41.3%, respectively, which is comparable to the case of a bare silica glass of approximately 1.6%. In addition, the thickness of the SiO2 protective layer was estimated to be approximately 0.44 µm for the 30-s laser irradiation by immersing the samples in 1 wt % hydrogen fluoride aqueous solution and measuring the depth using a surface profilometer.
Possible Origins of Extra Threshold Voltage Variability in N-Type Field-Effect Transistors by Intentionally Changing Process Conditions and Using Takeuchi Plot
Authors: Tsunomura Takaaki , Yano Fumiko , Nishida Akio , Hiramoto Toshiro
Published: July 2010

The origins of the threshold voltage (V
T) variability of n-type field-effect transistors (NFETs), which have larger V
T variability than p-type field-effect transistors (PFETs), are investigated using the Takeuchi plot and by intentionally changing process conditions. The process conditions investigated in this study are the polarity of polycrystalline silicon (poly-Si) gate electrodes, fluctuations of gate oxide thickness and gate oxide/substrate interface, and channel stress. It is confirmed by experiments that these process conditions negligibly affect V
T variability in NFETs. This result does not contradict our previous result that channel profile nonuniformity is the major origin of the larger V
T variability in NFETs than that in PFETs.
New Analytical Model for Short-Channel Fully Depleted Dual-Material-Gate Silicon-on-Insulator Metal–Oxide–Semiconductor Field-Effect Transistors
Authors: Chiang Te-Kuang
Published: July 2010

Using the exact solution of the two-dimensional Poisson equation, a new analytical model comprising two-dimensional potential and threshold voltage for short-channel fully depleted dual-material-gate silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) is developed. The model shows that the minimum acceptable channel length can be sustained while repressing the short-channel effects if a thin gate oxide and a thin silicon body are employed in the device. Moreover, by increasing the ratio of the screen gate length to control gate length, the threshold voltage roll-off can be more effectively reduced. The model is verified by the close agreement of its results with those of a numerical simulation using the device simulator MEDICI. The model not only offers an insight into the device physics but is also an efficient model for circuit simulation.
Bulk Crystal Growth of Stilbazolium Derivatives for Terahertz Waves Generation
Authors: Matsukawa Takeshi , Yoshimura Masashi , Takahashi Yoshinori , Takemoto Yoshiaki , Takeya Kei , Kawayama Iwao , Okada Shuji , Tonouchi Masayoshi , Kitaoka Yasuo , Mori Yusuke , Sasaki Takatomo
Published: July 2010

The two stilbazolium derivatives, 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) and 4-dimethylamino-N-methyl-4-stilbazolium p-chlorobenzenesulfonate (DASC), are organic ionic nonlinear optical materials that have a tendency to form bulk crystals when grown in a mixed solvent of methanol and acetonitrile. We observed the generation of broadband high-power terahertz (THz) waves from the bulk crystals of DASC. DASC crystals have superior transmission characteristics in the THz band than DAST crystals, and it is expected that the THz waves generated using DASC crystals will have higher power than those generated using DAST crystals.
Stress in Switchable Mirror Thin Film Resulting from Gasochromic Switching
Authors: Yoshimura Kazuki , Tajima Kazuki , Yamada Yasusei , Okada Masahisa
Published: July 2010

To enable the practical use of the switchable mirror thin film, an improvement of switching durability is crucial. One of the causes of film degradation is the modification of the Pd cap layer in accordance with the volume change upon hydrogenation and dehydrogenation, which is expected to be related to inner stress in switchable mirror thin films. In this study, we observed stress change in the switchable mirror thin film resulting from gasochromic switching and investigated the relationship between stress and switching durability. We found that the inner stress of the Pd layer is directly related to the switching durability of switchable mirror thin films.
Improvement of Al Filling Ability in Damascene Process
Authors: Kim Eun-Soo , Kim Jung-Geun , Cho Jong-Hye , Shin Jong-Han , Lee Byung-Seok , Kim Jin-Woong
Published: July 2010

A novel Al chemical vapor deposition (CVD) technique called “CVD Al reflow trench fill” was developed using methylpyrrolidine alane (MPA) as a precursor in a damascene structure. The new method is based on the changes in deposition properties of CVD Al with the MPA precursor depending on its under layer. Using this characteristic, we completely filled a 40 nm-spacing trench and confirmed robust electrical properties. These results were again verified by comparing the bit line property of the Al damascene scheme with those of the Al reactive ion etch (RIE) scheme and low resistivity W (LRW) damascene structures.
Activation of Silicon Implanted with Phosphorus and Boron Atoms by Infrared Semiconductor Laser Rapid Annealing
Authors: Ukawa Kan , Kanda Yasushi , Sameshima Toshiyuki , Sano Naoki , Naito Masao , Hamamoto Nariaki
Published: July 2010

We report the activation of silicon implanted with phosphorus and boron atoms by infrared semiconductor laser annealing using carbon films as an optical absorption layer. 2-µm surface region was heated above 1000 °C longer than 22 µs by scanning the laser beam for a dwell time of 40 µs. We carried out implantations of 1 ×1015 cm-2 phosphorus atoms at 100, 300, and 500 keV, and boron clusters with a boron concentration of 1 ×1015 cm-2 at 6 keV. Laser irradiation at 375 kW/cm2 was conducted to activate impurities. Secondary ion mass spectrometry measurement revealed that laser annealing caused no substantial change in the phosphorus and boron atom profiles. Laser-induced recrystallization of surface amorphized regions caused by the ion implantation was analyzed using the optical reflectivity spectra ranging from 250 to 1000 nm. The free carrier absorption analyses indicated that the phosphorus and boron atoms were effectively activated by laser annealing.
Removal Rate Simulation of Dissolution-Type Electrochemical Mechanical Polishing
Authors: Fukuda Akira , Kodera Akira , Toma Yasushi , Suzuki Tsukuru , Hiyama Hirokuni , Doi Toshiro , Kurokawa Syuhei , Ohnishi Osamu
Published: July 2010

A new method for simulating the Cu removal rate in electrochemical mechanical polishing (ECMP) based on the dissolution-type polishing mechanism was developed. The effect of a protective layer on the Cu removal rate was considered in this method because the protective layer is a key element in the dissolution-type polishing mechanism. This method was used to simulate the removal rate in a rotary-type ECMP system. The simulations accurately provided the dependence of the Cu removal rate on the aperture ratio. Furthermore, the dependence of the Cu removal rate on the aperture ratio was described with respect to changes in the average protective layer amount with time. Regarding the dependence of the Cu removal rate on the aperture diameter, however, a discrepancy was observed between the simulation and experimental results because this method did not take into account the effect of the aperture diameter on the electrolyte-filling ratio in apertures.
Centrifugal Separation Device Based on Two-Layer Laminar Flow in Microchannels for High-Throughput and Continuous Blood Cell/Plasma Separation
Authors: Kobayashi Taizo , Funamoto Taisuke , Hosaka Makoto , Konishi Satoshi
Published: July 2010

This paper presents a novel type of centrifugation device that is based on the two-layer laminar flow in micro flow channels for continuous blood cell/plasma separation. We propose to rotate the flow channels which are arranged along the circumference around the rotational axis. Downsizing the channel width reduced both the cell sedimentation time and the required centrifugal force, because the channel width corresponds to the centrifugal sedimentation length. First, plasma and cells were continuously extracted from pig blood in each of the branch channels using a milled acrylic prototype device (channel width = 800 µm, volume = 150 µl). Next, the relationship between the channel width (125, 250, and 500 µm) and the sedimentation time taken for various centrifugal forces (2.3, 9, 36, and 145 G) was evaluated using the downsized microchannels fabricated by hot-embossing and thermal bonding technologies. Using downsized microchannels with a width of 125 µm successfully reduced the sedimentation time to 85 s as compared to the sedimentation time of 270 s for a channel of a width of 500 µm, when a centrifugal force of 2.3 G was applied. The use of the proposed device did not result in obvious hemolysis at the centrifugal forces lower than 335 G.
Thermal Conductivity Measurements of Solid Sb2Te3 by Hot-Strip Method
Authors: Lan Rui , Endo Rie , Kuwahara Masashi , Kobayashi Yoshinao , Susa Masahiro
Published: July 2010

The thermal conductivity of solid Sb2Te3 has been measured by the hot strip method from room temperature to 789 K. The thermal conductivity of solid Sb2Te3 decreases with an increase in temperature up to approximately 500 K and then increases. It is proposed that phonon thermal conduction dominates the heat transport around room temperature although other mechanisms such as electron and ambipolar diffusion are also in operation. Ambipolar diffusion is thought to be more dominant at higher temperature and contributes to the increase in the thermal conductivity.
Molecular Recognition in the Digital Radio Domain
Authors: Hunt William D. , Edmonson Peter J. , Stubbs Desmond D. , Lee Sang-Hun
Published: July 2010

In this paper we discuss the theoretical and experimental constructs which together point the way towards the transduction of biomolecular recognition events into a palpable set of electrical signals. This combines the applied physics of surface perturbations on acoustic wave device surfaces and the biochemistry of the interactions between an immobilized biomolecule (e.g., an antibody) and a target molecule which is flowing past the sensor surface (e.g., an antigen). We will first provide the theoretical basis for our contention that we can extract information about both molecular recognition and conformational change from the electrical signal and will then confirm this assertion with experimental results relating to induced conformational changes in DNA on a quartz crystal microbalance (QCM) surface. Next we will discuss our digital radio technique whereby the real time measurements using antibody coated surface acoustic wave (SAW) devices in the vapor phase allow us to differentiate between close chemical analogs of nitro-based molecules (e.g., tri-nitro toluene vs musk oil) by virtue of the cross-reactivity of the antibody-antigen interaction. In immunochemistry this is referred to as antibody promiscuity. Finally, we present two- and three-dimensional plots illustrating our technique which derives much from in-phase and quadrature phase (IQ) mapping. The end result is a powerful technique which allows one to differentiate between target molecules and chemically similar interferrents.
Measurement of Elastic Constant and Refraction Index of Thin Films at Low Temperatures Using Picosecond Ultrasound
Authors: Tanigaki Kenichi , Kusumoto Tatsuya , Ogi Hirotsugu , Nakamura Nobutomo , Hirao Masahiko
Published: July 2010

In this paper, a picosecond ultrasound measurement is conducted to evaluate the low-temperature elastic and optical properties of thin films and semiconductors. Specimens are cooled with liquid He through a heat exchanger in a cryostat, and an ultrahigh-frequency acoustic pulse is generated using a femtosecond light pulse, which propagates in the film-thickness direction. Pulse echoes of the longitudinal wave and Brillouin oscillation are observed by the changes in reflectivity of the time-delayed probe light, which depend on the material, and give the longitudinal-wave out-of-plane elastic constant. When the stiffness is known, the Brillouin oscillation provides the refractive index. We determined the stiffness of a Pt thin film and the refractive index of Si at 5 K. The methodology developed in this paper is useful for studing the elastic and optical properties of metallic thin films and transparent materials at cryogenic temperatures.
Measurement of Wave Velocity Distribution in a Trabecula by Micro-Brillouin Scattering Technique
Authors: Kawabe Masahiko , Matsukawa Mami , Ohtori Norikazu
Published: July 2010

Ultrasonic wave velocities in small trabeculae of bovine femur were investigated using a micro-Brillouin scattering technique. Our micro-Brillouin scattering system enables the measurement of wave velocities in the GHz range over a minute area (diameter: approximately 10 µm). Using thin trabecular specimens with a thickness of about 150 µm, the distribution of longitudinal wave velocity in a trabecula was observed. In the direction parallel to the trabecular alignment, the velocity changed depending on the measurement position. We measured 20 different trabeculae in our specimens, and the average wave velocities in each trabecula were similar at approximately 4.92×103 m/s. In addition, the difference in average velocity was not statistically significant between trabeculae that align in the bone axis or anterior–posterior directions. These data tell us the possibility that the average wave properties are similar in all trabeculae.
Nondestructive Testing Technique for Defect Detection in LiNbO3 Using Infrared Thermal Imaging Camera
Authors: Lee Kunyong , Miyazaki Hisashi , Okamoto Yoichi , Morimoto Jun , Toda Kohji
Published: July 2010

The existence of defects in lithium niobate (LiNbO3) degrades the specific properties required of LiNbO3 as substrate material, which is a major problem inhibiting device constructions. For the purpose of providing a convenient and quick tool for use in a nondestructive testing technique for defect detection, the feasibility of using an infrared thermal imaging camera (IR camera) is examined by comparing the results of IR camera use with those of two methods, scanning laser microscopy (SLM) and light scattering tomography (LST). We have succeeded in the detection of defects in the LiNbO3 substrate by observing the thermal properties of defects in a relatively wide field of view (8×6 mm2) compared with the case of using conventional microscopes. The maximum temperature difference of the defects in the LiNbO3 substrate was 0.47 K.
Perfectly Matched Layers in the Cylindrical and Spherical Coordinates for Elastic Waves in Solids
Authors: Shimada Takao , Hasegawa Koji
Published: July 2010

The material constants of perfectly matched layers (PMLs) in the cylindrical and spherical coordinates in the frequency domain are presented. Using the coordinate transformation laws of tensors on manifolds, the quotient rule, and complex coordinate stretching, we obtain the material parameters of PMLs in the real coordinate. Our results show that PML parameters for elastic waves may be determined by the same procedure in the Cartesian coordinates. However, this rule has been determined for PML material constants derived from the analytic continuation in the cylindrical and spherical coordinates by Zheng and Huang in 2002. Our derivation based on differential forms shows that this rule holds for PML parameters in any orthogonal coordinate system.
Numerical Analysis of Piezoelectric Sensor Using Multimode Vibration for Liquid Density and Viscosity Measurement
Authors: Takarada Jun , Wakatsuki Naoto , Mizutani Koichi , Yamamoto Ken
Published: July 2010

We report a new piezoelectric sensor for measuring the density and viscosity of liquids. This sensor can selectively vibrate in directions normal and tangent to the contact surface between the sensor and a liquid by choosing appropriate driving methods. In the proposed system, the density and viscosity can be presumed simply by measuring resonance frequencies in air and liquid for the vibration in the tangent and normal directions instead of measuring resonance frequency and damping of a single vibration mode for use in conventional method. In this report, we firstly derive a theoretical model of a plate vibrating in two directions with respect to the contact surface. Next, the proposed device is designed and evaluated by the finite element method (FEM). The validity of this calculation is ensured by comparison of an early experimental result and the result of the FEM. From this analysis, we find that the density and viscosity of a sample liquid were presumed within 2% error.
Three-Dimensional Sound Field Rendering with Digital Boundary Condition using Graphics Processing Unit
Authors: Tsuchiya Takao
Published: July 2010

A boundary condition with arbitrary frequency characteristics called a digital boundary condition is realized by an infinite impulse response (IIR) digital filter. The digital boundary condition is integrated with a three-dimensional sound field renderer using the digital Huygens' model (DHM), then it is implemented into a Graphics Processing Unit (GPU). Numerical demonstrations are carried out for three-dimensional sound propagation in a cubic room. It is confirmed that the presented model is valid for a boundary condition with arbitrary frequency characteristics.
Detection and Imaging of Nonmetallic Inclusions in Continuously Cast Steel Plates by Higher Harmonics
Authors: Kawashima Koichiro , Ito Toshihiro , Nagata Yasuaki
Published: July 2010

Nonmetallic inclusions within coarse columnar dendrites in continuously cast steel plates were detected and imaged by a nonlinear ultrasonic imaging technique. The nonlinear response of the inclusion/steel interface to tensile and compressive stress results in waveform distortion of the incident tone-burst wave, namely, higher harmonics in the frequency domain. By extracting the second harmonic with a band-pass filter and mapping the amplitude, small nonmetallic inclusions trapped at the bottom of coarse columnar dendrites were detected and imaged.
Image Quality Improvement of Ultrasonic Computed Tomography on the Basis of Maximum Likelihood Expectation Maximization Algorithm Considering Anisotropic Acoustic Property and Time-of-Flight Interpolation
Authors: Fan Honghui , Yanagida Hirotaka , Tamura Yasutaka , Guo Shuqiang , Saitoh Tadashi , Takahashi Tatsuhisa
Published: July 2010

The anisotropic acoustic property is considered for the purpose of improving the image quality of the ultrasonic computed tomography (CT) scans of a wooden pillar. We propose a velocity anisotropy correction method of time-of-flight (TOF) data for image reconstruction on the basis of the maximum likelihood-expectation maximization (ML-EM) method. We also examine the effect of the interpolation of the TOF data as the density of the TOF data has a considerable effect on image quality in the ML-EM method. The feasibility of velocity anisotropy correction and TOF data interpolation are examined in detail using numerical and wood phantoms.
Analysis of Anisimkin's Quasilongitudinal Modes in Piezoelectric Plate
Authors: Onoe Morio , Kaga Shigetaka
Published: July 2010

In 2004, Anisimkin found numerically and verified experimentally peculiar (quasilongitudinal, QL) modes propagating along the x (diagonal) axis in a quartz ST cut plate. Gulyaev conducted further studies, also numerically. This paper presents a mathematical analysis. A formula to yield “allowed” bands for QL-modes is obtained. The formula also covers newly found quasishear (QS) modes.
Finite-Element Analysis and Experimental Study of Frequency-Change-Type Two-Axis Acceleration Sensor
Authors: Sugawara Sumio , Kajiwara Yu
Published: July 2010

The operation of the frequency-change-type two-axis acceleration sensor utilizing the phenomenon that the resonance frequency of a bending vibrator changes by the axial force is confirmed experimentally. The sensor is composed of two developed bending vibrators, a mass, support bars, and a frame for fixation. The experimental sample of the sensor is made of stainless steel and the volume is about 90.0 ×95.8 ×10.2 mm3. The first out-of-plane mode of the vibrator is used here and the resonance frequency is about 1,687.8 Hz. The vibrator is driven electrically by small piezoelectric ceramics. The relationship between the applied acceleration and the resonance frequency change was analyzed using the finite-element method, and then measured in the gravitational field. As a result, the analyzed characteristics of the sensor agreed with the experimental ones.
Array Configurations for Higher Power Generation in Piezoelectric Energy Harvesting
Authors: Koyama Daisuke , Nakamura Kentaro
Published: July 2010

To realize a piezoelectric energy-harvesting device with higher volume energy density, the energy conversion efficiencies of different array configurations were investigated. The energy conversion efficiencies of the energy-harvesting element with several array configurations were calculated by finite element analysis (FEA). For the same volume of 22 ×19 ×1 mm3, one array configuration has two large cantilevers (18 ×9.5 ×1 mm3) and one has eight small cantilevers (9 ×4.25 ×1 mm3). One-mm-thick piezoelectric zirconate titanate (PZT) elements were attached on the surface of each aluminum cantilever. A harmonic vibration was applied and the electric power generated was measured by connecting a load resistance. A higher volume energy density was obtained with the smaller array configuration. A maximum output power of 2.8 mW and a conversion efficiency of 8.1% were achieved for a vibration velocity of 0.7 mm/s and a load resistance of 51 kΩ.
Contour-Mode AlN Resonator with High Coupling Factor
Authors: Isobe Atsushi , Asai Kengo
Published: July 2010

A micro electro mechanical systems (MEMS) type contour-mode resonator with a high coupling factor of several percent is proposed. The fabricated 60-MHz-band radial-extensional resonators using MEMS process technology of AlN film exhibited a high coupling factor of 2.8% and high Q values of 3000 at the series resonant frequency and 4000 at the parallel resonant frequency. We demonstrated a Pierce type oscillator using the radial-extensional resonators and achieved low power consumption and stable oscillation. These radial-extensional resonators were suitable for filter and oscillator applications because the figure of merit, defined as the ratio of the Q value and the capacitance ratio, was 71 at the series resonant frequency and 94 at the parallel resonant frequency, which were the highest values of the contour-mode AlN resonators.
A Multiple-Scan Focusing Method for Radio Frequency Bulk Acoustic Wave Device Observation by Laser Probe System
Authors: Wu Nan , Hashimoto Ken-ya , Omori Tatsuya , Yamaguchi Masatsune
Published: July 2010

This paper proposes a focusing method based on multiple scanning of a device surface to be observed, which is particularly-suitable for a fast-mechanical-scanning and phase-sensitive laser probe for radio frequency (RF) surface and bulk acoustic wave (SAW/BAW) devices. When high spatial resolution is required for the observation, one needs an objective lens of large magnifying power with extremely shallow focal depth. Accordingly, an uneven surface and tiny inclination of a BAW device cause acquired images a considerable defocus, by which it is difficult to obtain precise and reliable field quantities related to acoustic waves in the device. The proposed method is shown to be most effective in avoiding this sort of defocus and able to focus the entire surface. By this method, for example, we could clearly observe power leakage in an FBAR structure.
Nonlinear Distortion of Acoustic Devices for Radio-Frequency Front-End Circuit and Its Suppression
Authors: Ueda Masanori , Iwaki Masafumi , Nishihara Tokihiro , Satoh Yoshio , Hashimoto Ken-ya
Published: July 2010

In this paper, we discuss the nonlinear performance difference between surface acoustic wave (SAW) and bulk acoustic wave (BAW) resonators, which include intermodulation distortion (IMD) or triple-beat (TB) products, and indicate the importance of reducing even-order nonlinearities of BAW resonators. We were able to validate the accuracy and efficiency of our proposed simulation technique for BAW devices by comparing the results of our simulation with experimental data. We verified that our circuit model is a high-performance tool that can be used to predict BAW device nonlinearities, and we propose how to suppress even-order nonlinearities by employing a thin-film bulk acoustic resonator (FBAR) duplexer for wideband code division multiple access (WCDMA) band 1. Finally, we introduce highly linear FBAR duplexers.
Development of Multiple-Gas Analysis Method Using the Ball Surface Acoustic Wave Sensor
Authors: Yamamoto Yutaro , Akao Shingo , Nagai Hiroki , Sakamoto Toshihiro , Nakaso Noritaka , Tsuji Toshihiro , Yamanaka Kazushi
Published: July 2010

In the fields of energy exploitation, and for the safety and security of society, portable multiple-gas sensors are essential. Although the gas chromatograph (GC) is applicable to multiple-gas analysis, it is not portable. As a result, we have proposed the ball surface acoustic wave (SAW) GC using a ball SAW sensor, which realizes high sensitivity by the ultramultiple roundtrip propagation of a SAW and a separation column fabricated by micro-electro-mechanical-system technology. However, it takes too long for a portable GC such as the ball SAW GC to analyze mixed gases of high and low molecular weights at the same time. In this study, we developed the forward-flush (FF) method, involving two (or more) separation columns with a ball SAW sensor inserted after each column, to solve the above problem. Using the ball SAW GC with the FF method, we analyzed mixed gases of natural gas components and volatile organic compounds.
Liquid-Phase Shear Horizontal Surface Acoustic Wave Immunosensor
Authors: Kogai Takashi , Yoshimura Naoyuki , Mori Toshimasa , Yatsuda Hiromi
Published: July 2010

In this paper, we describe liquid-phase immunosensors based on shear horizontal surface acoustic waves (SH-SAWs), which can be directly dipped into a liquid. The sensor devices are fabricated using an SH-SAW delay line on quartz and LiTaO3 substrates, which is composed of a transmitting floating electrode unidirectional transducer (FEUDT), receiving FEUDT, and a biochemical reaction area between them. These FEUDTs are protected from liquids by a glass lid and epoxy walls, which are constructed using a photolithography technique. Therefore, the sensor devices can be directly dipped into a liquid and a liquid can be directly applied onto the surface of the sensor devices. In order to evaluate basic characteristics of the sensor devices, glycerol–water mixture liquids of different viscosities were used. For evaluations of their applicability to immunoassay, human serum albumin antigen–antibody reactions were investigated.
Characteristics of ZnO Thin Film Surface Acoustic Wave Devices Fabricated Using Al2O3 Films on Silicon Substrates
Authors: Shih Wen-Ching , Wang Tzyy-Long , Chu Ming-Hsien
Published: July 2010

ZnO films with a c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on interdigital transducer (IDT)/Al2O3/SiO2/Si substrates. Al2O3 films were deposited on SiO2/Si substrates by electron beam evaporation. The crystalline structure and surface roughness of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The second-order phase velocity of a surface acoustic wave (SAW) device with a 7.5-µm-thick Al2O3 film was measured to be about 5432 m/s, which approaches (93%) that (5840 m/s) of ZnO/IDT/sapphire. This experimental result indicates that a low-cost Al2O3 film can be used to replace an expensive single-crystalline sapphire substrate for the fabrication of high-frequency SAW devices and is also useful in the integration of semiconductor and high-frequency SAW devices on the same Si substrate.
Analysis of Rayleigh-Mode Spurious Response Using Finite Element Method/Spectrum Domain Analysis for Surface Acoustic Wave Resonator on Nonflat SiO2/Al/LiNbO3 Structure
Authors: Nakamura Hiroyuki , Nakanishi Hidekazu , Goto Rei , Hashimoto Ken-ya , Yamaguchi Masatsune
Published: July 2010

Because of their low insertion loss, high out-of-band rejection, and high power durability, miniature surface acoustic wave (SAW) duplexers are widely used in mobile phones. Substrate materials substantially limit and determine the performance of SAW duplexers; for their applications to Band I and Band IV systems with large pass-band widths and wide frequency separations between the transmitting and receiving frequency bands, a larger coupling coefficient (K
2) is of primary importance. We have developed a shape-controlled SiO2 film/Al electrode/LiNbO3 substrate structure for their applications. It could lead to a large K
2 and suppression of Rayleigh-mode spurious response. In this paper, we report the analysis using finite element method/spectrum domain analysis (FEM/SDA) for the SAW resonator on a nonflat SiO2 film/Al electrode/LiNbO3 structure. It was clarified that the shape-controlled SiO2 was effective in terms of achieving a large K
2 for the SAW resonator with suppressed Rayleigh-mode spurious responses and bulk wave radiation. Furthermore, the experiment results showed a good agreement with the analysis results.
High-Electromechanical-Coupling-Coefficient Surface Acoustic Wave Resonator on Ta2O5/Al/LiNbO3 Structure
Authors: Nakanishi Hidekazu , Nakamura Hiroyuki , Goto Rei
Published: July 2010

In this paper, we describe a high-electromechanical-coupling-coefficient (K
2) surface acoustic wave (SAW) resonator on a Ta2O5/Al/LiNbO3 structure for wide duplex gap applications. We analyzed the responses of a SAW resonator on a Ta2O5/Al/LiNbO3 structure by finite element method (FEM)/spectrum domain analysis (SDA). We have clarified that the optimum Ta2O5 thickness at which the high-performance SAW resonator without the Rayleigh-mode spurious response could be realized. The results of the simulation were in good agreement with those of the experiment. Also, the Ta2O5 film has the advantage of decreasing the film thickness over the SiO2 film. The developed SAW resonator shows excellent characteristics, namely, a low insertion loss and a high K
2 of 23%. By applying the SAW resonator in the filters, a ladder-type filter and a longitudinally-coupled double-mode SAW (DMS) filter with a low insertion loss and a large bandwidth were realized. We have therefore shown the feasibility of applying devices with a wide duplex gap such as Band I, IV, and X duplexers and a wide pass-band filter using the Ta2O5/Al/5°YX-LiNbO3 structure.
Theoretical Analysis of Electromechanical Coupling Coefficient of Lamb Waves in ZnO/Si Multilayered Piezoelectric Plates
Authors: Chen Yung-Yu
Published: July 2010

Lamb wave devices have been widely used in electro-acoustic and microfluidic devices. In order to improve their performances, the phase velocity dispersion and electromechanical coupling coefficient (ECC) of the Lamb wave should be calculated exactly during designing. Accordingly, this paper aims at analyzing exactly Lamb waves in multilayered piezoelectric plates with distinct electrode arrangements. First, the formulae of effective permittivity were derived based on the transfer matrix method and further was employed to calculate the phase velocity dispersion. The ZnO/Si multilayered plate was taken as the calculation example. The ECCs under distinct electrical boundary conditions were calculated by the Green's function method. Finally, the influences of the silicon thickness on the phase velocity dispersion and ECC are further discussed. Results show that the coupling coefficients deeply depends on the electrode arrangement, and the S0 mode with the electrode arrangements of type D is a better due to its larger velocity and higher coupling coefficient. Moreover, the ECC can be enlarged by reducing the nonpiezoelectric membrane thickness.
Tunable Radio-Frequency Filters Using Acoustic Wave Resonators and Variable Capacitors
Authors: Komatsu Tomoya , Hashimoto Ken-ya , Omori Tatsuya , Yamaguchi Masatsune
Published: July 2010

In this paper, we describe possible configurations for tunable filters based on RF surface or bulk acoustic wave (SAW/BAW) technologies. The frequency tuning is made possible by variable capacitors (VCs) connected to SAW/BAW resonators in the ladder-type filter configuration. First, it is shown that the passband edges can be controlled by one VC connected to each resonator. Second, it is discussed that the width and location of a passband can be controlled flexibly by two VCs connected to each resonator both in parallel and in series. Finally, the SAW filters with the proposed configuration are fabricated on a Cu-grating/15°YX-LiNbO3 substrate structure, and the tuning capability is demonstrated.
Tunable Filters Using Ultrawide-Band Surface Acoustic Wave Resonator Composed of Grooved Cu Electrode on LiNbO3
Authors: Kadota Michio , Kimura Tetsuya , Ida Yasuyuki
Published: July 2010

A leaky surface acoustic wave (LSAW) with a leaky component on a 0–15°YX-LiNbO3 substrate has a large electromechanical coupling factor. In order to change the LSAW to a Love wave without a leaky component, a high-density electrode with a low velocity such as a Au or Cu electrode is composed on the substrate. A SAW resonator with a Cu-electrode/15°YX-LiNbO3 structure has been reported to have a wide bandwidth of 12%. In this study, in order to obtain a SAW resonator with a wider bandwidth for application to tunable filters, the authors fabricated one-port resonators with a grooved Cu-electrode/4°YX-LiNbO3 structure. This resonator had a 1.3-fold wider bandwidth of 17% and 1.3-fold higher resonant and antiresonant frequencies than a conventional resonator composed of the same thick Cu-electrode on 4°YX-LiNbO3 fabricated for reference. Moreover, the authors proposed the application of this resonator to a tunable filter by using a circuit to modify a conventional band-pass filter composed of inductors and capacitors (LC) and a tunable filter with a ladder-type circuit. As a result, tunable filters having tunable ranges of 7 and 9% at the center frequency and 3 dB bandwidths of 3 and 5%, respectively, have been realized.
Sonophotocatalysis of Malonic Acid Solution: Possibility of a New Contribution to Organic Reactions
Authors: Naruke Yukio , Goto Mika , Tanaka Hisashi , Harada Hisashi
Published: July 2010

The synergistic effects of the combination of sonolysis and photocatalysis of malonic acid were examined. Not only increase in the reaction rate but also elongation of the carbon chain was observed. Firstly, the decomposition rate of malonic acid in the solution was improved; that is, the reaction rate for a combined system was higher than the sum of the rates of sonolysis and photocatalysis. Secondly, a small amount of succinic acid was detected; that is, the carbon numbers of dicarboxylic acid increased from C = 3 (malonic acid) to C = 4 (succinic acid) by sonophotocatalysis. It means the process of increasing molecular weight. We consider that this combined system will probably make a valuable contribution to organic reactions in the near future.
Effects of Different Ultrasound Irradiation Frequencies and Water Temperatures on Extraction Rate of Bitumen from Oil Sand
Authors: Okawa Hirokazu , Saito Tomonao , Hosokawa Ryota , Nakamura Takashi , Kawamura Youhei , Sugawara Katsuyasu
Published: July 2010

Low (28 kHz) and high (200 kHz) frequency sonication combined with hot water treatments at 45 and 75 °C were investigated to assess the effects of different ultrasound frequencies and water temperatures on the extraction of bitumen from oil sand. A mechanical stirrer was also used to compare the efficiency of separation. Bitumen extraction tests were performed under argon, air, and nitrogen atmospheres. Sonication at 200 kHz was shown to extract bitumen effectively from oil sand at 75 °C. The bitumen extraction rate for sonication at 200 kHz was slightly higher than that at 28 kHz. For low temperature (45 °C) solutions, only sonication at 28 kHz could extract bitumen from oil sand, demonstrating that sonication at 28 kHz can effectively breakdown the oil sand aggregates into a suspension.
Emulsion Generating Microchannel Device Oscillated by 2.25 MHz Ultrasonic Vibrator
Authors: Harada Takuya , Kanda Takefumi , Suzumori Koichi , Ono Tsutomu , Iwabuchi Sotaro , Ito Kazuyuki , Ogawara Ken-ichi , Higaki Kazutaka
Published: July 2010

In this study, a device using an ultrasonic vibration and a microchannel has been developed to obtain emulsions. The process of generating emulsions involves a Y-type microchannel and an ultrasonic device. Once micron-sized emulsions were generated by the Y-type microchannel, the micron-sized emulsions were sonicated using ultrasonic vibration to produce emulsions. Although the diameter of emulsions was 30 µm using the Y-type microchannel, the diameter of the sonicated emulsions was about 200 nm. In addition, as the applied voltage was increased, sonicated emulsions became smaller and the distribution became sharper.
Finite Element Analysis of Acoustic Streaming in an Ultrasonic Air Pump
Authors: Wada Yuji , Koyama Daisuke , Nakamura Kentaro
Published: July 2010

An ultrasonic air pump utilizing acoustic streaming is discussed and its accurate simulation method using finite element analysis (FEA) is suggested in this paper. The pump induces air streaming in a thin air layer between a bending transducer and a reflector by exciting an intense sound field. The absolute sound pressure and streaming velocity in the air layer are calculated on the basis of full-fluid dynamics through FEA, and the calculation results are compared with experimental results for the sound pressure and flow velocity. As a result, the sound pressure is calculated in the derivation of the error of 5.9%, and the measurement and analysis results for the streaming distribution are in good agreement.
Sound Field Characteristics in Air Gaps of Noncontact Ultrasonic Motor Driven by Two Flexural Standing Wave Vibration Disks
Authors: Yamayoshi Yasuhiro , Shiina Jun , Tamura Hideki , Hirose Seiji
Published: July 2010

The sound field characteristics in the air gaps of the noncontact ultrasonic motor driven by two flexural standing wave vibration disks were analyzed by finite element method (FEM). Standing wave sound fields with an opposite phase were generated in the two air gaps by a single driving stator. Traveling wave sound fields in the two air gaps are formed as the superposition of the standing wave sound fields generated by two stators whose temporal phases and spatial positions are different from each other. The traveling direction of the calculated sound fields coincided with the rotating direction of the rotor observed in the experiments. The intensity of the sound field generated in the air gap by the single driving stator was measured by detecting the voltage induced in another stator. A gap distance wider than 0.5 mm is required for a high revolution speed because the sound field generated in the gap on the opposite side of the rotor is weak in an air gap narrower than 0.3 mm.
Miniaturization of the Loop-Tube-Type Thermoacoustic Cooling System: Effect of the Installation Position of Heat Pump and Working Gas in the Tube
Authors: Hotta Kohei , Sakamoto Shin-ichi , Tsukamoto Daichi , Watanabe Yoshiaki
Published: July 2010

A loop-tube-type thermoacoustic cooling system uses heat energy as a power source. Therefore, it is possible to put a loop tube into practical use in different areas. Several reports have described total loop tube lengths greater than 3 m. Additional miniaturization is necessary to apply this system to electronic devices such as personal computers. As described herein, to realize a miniature loop tube, an A4-size loop tube (850 mm total length; 24 mm inner diameter) was designed. Furthermore, to assess this system's cooling properties, two experimental investigations were carried out. One is to elucidate the heat pump installation position. The other is to assess the working gas in the tube. An A4-size loop tube driven on the basis of those experimental results achieved cooling from room temperature to 0 °C.
Effects on the Performance of Parametric Loudspeaker Caused by Nonideal Ultrasound Transducer
Authors: Wu Ming , Ye Chao , Wu Shuaibin , Huang Chenxi , Yang Jun
Published: July 2010

In this paper, we report the effects on the performance of a parametric loudspeaker caused by a nonideal ultrasound transducer. The frequency contents of self-demodulated secondary wave pressure for the nonideal ultrasound transducer are first derived on the basis of Berktay's solution. Then, according to the relationship between the input signal and the envelope of primary wave pressure, the harmonic distortion and intermodulation distortion are obtained for different modulation techniques. Simulation experiments show that in the case of using the double-sideband amplitude modulation (DSB-AM) technique, the amplitudes of the fundamental frequency and intermodulation distortion components are affected by both the phase and magnitude response of the ultrasound transducer, whereas the harmonic distortion component is only affected by the phase response. In the case of using the single-sideband amplitude modulation (SSB-AM) technique, the amplitudes of the fundamental frequency component and intermodulation distortion components are only affected by the magnitude response of the transducer.