50 results on '"Ryosuke Shimizu"'
Search Results
2. Local Structure of Glassy Lithium Phosphorus Oxynitride Thin Films: A Combined Experimental and Ab Initio Approach
- Author
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Maxwell A. T. Marple, Thomas A. Wynn, Diyi Cheng, Ryosuke Shimizu, Harris E. Mason, and Y. Shirley Meng
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GIPAW ,Materials science ,LiPON ,Ab initio ,FOS: Physical sciences ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,Ion ,chemistry.chemical_compound ,Ab initio quantum chemistry methods ,Fast ion conductor ,Thin film ,solid electrolytes ,solid-state NMR spectroscopy ,Condensed Matter - Materials Science ,010405 organic chemistry ,ab initio calculations ,Organic Chemistry ,Materials Science (cond-mat.mtrl-sci) ,General Medicine ,General Chemistry ,Nuclear magnetic resonance spectroscopy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Amorphous solid ,Monomer ,Chemical engineering ,chemistry ,Chemical Sciences ,0210 nano-technology - Abstract
Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. We provide a structural model of RF-sputtered LiPON via experimental and computational spectroscopic methods. Information about the short-range structure results from 1D and 2D solid-state nuclear magnetic resonance experiments investigating chemical shift anisotropy and dipolar interactions. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility highlighting the unique mechanical properties of glassy materials.
- Published
- 2020
3. Numerical simulation of the melting process of an ice on a horizontal heated plate
- Author
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Ryosuke Shimizu and Mitsuhiro Ohta
- Subjects
Materials science ,Computer simulation ,Process (computing) ,Mechanics - Published
- 2020
4. The Negative Impact of Transition Metal Migration on Oxygen Redox Activity of Layered Cathode Materials for Na-Ion Batteries
- Author
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Enyue Zhao, Ryosuke Shimizu, Minghao Zhang, Yixuan Li, Ying Shirley Meng, Hayley Hirsh, and Ju-Hsiang Cheng
- Subjects
Materials science ,Energy ,Renewable Energy, Sustainability and the Environment ,XRD ,Inorganic chemistry ,chemistry.chemical_element ,Materials Engineering ,Energy Storage ,Condensed Matter Physics ,Oxygen ,Cathode ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Redox Activity ,law.invention ,X-ray diffraction ,Macromolecular and Materials Chemistry ,Batteries ,Affordable and Clean Energy ,Transition metal ,chemistry ,law ,Materials Chemistry ,Electrochemistry ,Physical Chemistry (incl. Structural) - Abstract
Rechargeable sodium ion batteries with high energy density are a promising technology to address the demand for grid storage. Cathode materials with oxygen redox activity exhibit higher energy density than expected from Na-ion removal and charge compensation solely by transition metal redox. One strategy to enable oxygen redox in materials is to alter the oxygen environment through transition metal layer ordering. In this work, we report the investigation of oxygen redox activity induced by transition metal ordering in P2-type Na0.8Li0.12Ni0.22Mn0.66O2 cathode synthesized by carbonate co-precipitation. Irreversible oxygen activity was observed and correlated with Ni migration that resulted in the loss of transition metal ordering in the structure. Calculated density of states shows that after Ni migration, the number of unoccupied states of O above Fermi level decreases, inhibiting the reduction of oxygen during sodiation. This paper provides insights on how Ni migration has a detrimental effect on transition metal ordering and reversibility of oxygen redox at high voltage.
- Published
- 2021
5. Creep and solvent squeeze behavior of κ-carrageenan gels under compression
- Author
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Koichi Yao, Ryosuke Shimizu, Takuma Tanigawa, Jun-ichi Horinaka, and Toshikazu Takigawa
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chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Compression (physics) ,01 natural sciences ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Colloid and Surface Chemistry ,chemistry ,Creep ,Permeability (electromagnetism) ,Spring (device) ,Phenomenological model ,Materials Chemistry ,Physical and Theoretical Chemistry ,Composite material ,0210 nano-technology ,Constant (mathematics) ,Displacement (fluid) - Abstract
Creep by solvent squeeze of cylindrical κ-carrageenan gels is investigated. A phenomenological model to describe the creep and the solvent squeeze of polymer gels is also presented. Under compression, the creep of gels proceeds at a constant diameter except for the initial stage of creep. The change in height of the gels is well reproduced by the sum of three exponential terms, each of which is specified by the combination of displacement and retardation time. The displacement for the second mode, which corresponds to the second longest retardation time, becomes largest for all gel specimens. Three retardation times are commonly proportional to the square of initial diameter of gel specimens. Based on the proposed model, the spring constant in the second mode becomes smallest and the permeability corresponding to the third mode becomes larger than those in the other two modes.
- Published
- 2019
6. Mid-infrared spectrally-uncorrelated biphotons generation from doped PPLN: a theoretical investigation
- Author
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Qiang Zhou, Rui-Bo Jin, Bei Wei, Ryosuke Shimizu, Chunling Ding, Guang-Wei Deng, and Wu-Hao Cai
- Subjects
Materials science ,FOS: Physical sciences ,02 engineering and technology ,01 natural sciences ,010309 optics ,Crystal ,Condensed Matter::Materials Science ,Optics ,Interference (communication) ,Condensed Matter::Superconductivity ,0103 physical sciences ,Thermal ,Range (particle radiation) ,Quantum Physics ,business.industry ,Poling ,Doping ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Wavelength ,Tilt (optics) ,Optoelectronics ,Quantum Physics (quant-ph) ,0210 nano-technology ,business ,Optics (physics.optics) ,Physics - Optics - Abstract
We theoretically investigate the preparation of mid-infrared (MIR) spectrally-uncorrelated biphotons from a spontaneous parametric down-conversion process using doped LN crystals, including MgO doped LN, ZnO doped LN, and In2O3 doped ZnLN with doping ratio from 0 to 7 mol%. The tilt angle of the phase-matching function and the corresponding poling period are calculated under type-II, type-I, and type-0 phase-matching conditions. We also calculate the thermal properties of the doped LN crystals and their performance in Hong-Ou-Mandel interference. It is found that the doping ratio has a substantial impact on the group-velocity-matching (GVM) wavelengths. Especially, the GVM2 wavelength of co-doped InZnLN crystal has a tunable range of 678.7 nm, which is much broader than the tunable range of less than 100 nm achieved by the conventional method of adjusting the temperature. It can be concluded that the doping ratio can be utilized as a degree of freedom to manipulate the biphoton state. The spectrally uncorrelated biphotons can be used to prepare pure single-photon source and entangled photon source, which may have promising applications for quantum-enhanced sensing, imaging, and communications at the MIR range., 11 pages, 9 figures
- Published
- 2020
7. Unveiling the Stable Nature of the Solid Electrolyte Interphase between Lithium Metal and LiPON via Cryogenic Electron Microscopy
- Author
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Weikang Li, Minghao Zhang, Chengcheng Fang, Suk Jun Kim, Xuefeng Wang, Bingyu Lu, Han Nguyen, Shen Wang, Min-cheol Kim, Diyi Cheng, Thomas A. Wynn, Ying Shirley Meng, Ryosuke Shimizu, and Shuang Bai
- Subjects
Battery (electricity) ,Condensed Matter - Materials Science ,Materials science ,Nanostructure ,Lithium fluoride ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,Electrolyte ,Applied Physics (physics.app-ph) ,Physics - Applied Physics ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Anode ,chemistry.chemical_compound ,General Energy ,Chemical engineering ,chemistry ,Fast ion conductor ,Interphase ,Crystallite ,0210 nano-technology - Abstract
The solid electrolyte interphase (SEI) is regarded as the most complex but the least understood constituent in secondary batteries using liquid and solid electrolytes. The nanostructures of SEIs were recently reported to be equally important to the chemistry of SEIs for stabilizing Li metal in liquid electrolyte. However, the dearth of such knowledge in all-solid-state battery (ASSB) has hindered a complete understanding of how certain solid-state electrolytes, such as LiPON, manifest exemplary stability against Li metal. Characterizing such solid-solid interfaces is difficult due to the buried, highly reactive, and beam-sensitive nature of the constituents within. By employing cryogenic electron microscopy (cryo-EM), the interphase between Li metal and LiPON is successfully preserved and probed, revealing a multilayer mosaic SEI structure with concentration gradients of nitrogen and phosphorous, materializing as crystallites within an amorphous matrix. This unique SEI nanostructure is less than 80 nm and is shown stable and free of any organic lithium containing species or lithium fluoride components, in contrast to SEIs often found in state-of-the-art organic liquid electrolytes. Our findings reveal insights on the nanostructures and chemistry of such SEIs as a key component in lithium metal batteries to stabilize Li metal anode.
- Published
- 2020
8. Unveiling the Stable Nature of the Solid Electrolyte Interphase between Lithium Metal and Lipon Via Cryogenic Electron Microscopy
- Author
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Ryosuke Shimizu, Shuang Bai, Min-cheol Kim, Minghao Zhang, Shen Wang, Weikang Li, Han Nguyen, Suk Jun Kim, Bingyu Lu, Diyi Cheng, Ying Shirley Meng, Thomas A. Wynn, Chengcheng Fang, and Xuefeng Wang
- Subjects
Battery (electricity) ,Materials science ,Nanostructure ,chemistry.chemical_element ,Lithium fluoride ,Electrolyte ,Metal ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,Fast ion conductor ,Lithium ,Crystallite - Abstract
The solid electrolyte interphase (SEI) is regarded as the most complex but the least understood constituent in secondary batteries using liquid and solid electrolytes. The nanostructures of SEIs were recently reported to be equally important to the chemistry of SEIs for stabilizing Li metal in liquid electrolyte. However, the dearth of such knowledge in all-solid-state battery (ASSB) has hindered a complete understanding of how certain solid-state electrolytes, such as LiPON, manifest exemplary stability against Li metal. Characterizing such solid-solid interfaces is difficult due to the buried, highly reactive, and beam-sensitive nature of the constituents within. By employing cryogenic electron microscopy (cryo-EM), the interphase between Li metal and LiPON is successfully preserved and probed, revealing a multilayer mosaic SEI structure with concentration gradients of nitrogen and phosphorous, materializing as crystallites within an amorphous matrix. This unique SEI nanostructure is less than 80 nm and is shown stable and free of any organic lithium containing species or lithium fluoride components, in contrast to SEIs often found in state-of-the-art organic liquid electrolytes. Our findings reveal insights on the nanostructures and chemistry of such SEIs as a key component in lithium metal batteries to stabilize Li metal anode.
- Published
- 2020
9. Unveiling the Stable Nature of Lipon-Associated Electrode/Electrolyte Interphases via Cryogenic Electron Microscopy
- Author
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Minghao Zhang, Ying Shirley Meng, Diyi Cheng, Bingyu Lu, Jamie L. Weaver, and Ryosuke Shimizu
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Materials science ,Chemical engineering ,law ,Electrode ,Electrolyte ,Electron microscope ,law.invention - Published
- 2021
10. Quantifying lithium loss in amorphous silicon thin-film anodes via titration-gas chromatography
- Author
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Diyi Cheng, Wurigumula Bao, Darren H. S. Tan, Minghao Zhang, Bhagath Sreenarayanan, Bingyu Lu, Yihui Zhang, Weikang Li, Chengcheng Fang, Ryosuke Shimizu, Shuang Bai, and Ying Shirley Meng
- Subjects
Amorphous silicon ,Materials science ,Silicon ,Alloy ,technology, industry, and agriculture ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,General Chemistry ,Electrolyte ,engineering.material ,equipment and supplies ,Lithium-ion battery ,Anode ,chemistry.chemical_compound ,General Energy ,chemistry ,Chemical engineering ,engineering ,General Materials Science ,Lithium ,Faraday efficiency - Abstract
Summary Silicon with a high theoretical capacity (3,579 mAh/g) is a promising anode candidate for lithium-ion batteries. However, commercialization is still impeded by low Coulombic efficiency, caused by solid electrolyte interphase (SEI) formation and trapped lithium (Li)-silicon (Si) alloy during repeated volume change. Quantifying capacity losses from each factor is crucial to formulate rational design strategies for further improvement. In this work, titration-gas chromatography and cryogenic transmission electron microscopy are applied to characterize the evolution of trapped Li-Si alloy and SEI growth in a silicon thin-film anode. It is found that continuous growth of the SEI is the dominant factor for lithium inventory loss during cycling, with only a marginal increase in trapped Li-Si alloy. This study offers a quantitative approach to differentiate Li in the SEI from trapped Li in Li-Si alloy through a silicon thin-film anode, providing unique insights into identifying critical bottlenecks for developing Si anodes.
- Published
- 2021
11. Studies on the sol-gel transition entropy of κ-carrageenan/water system
- Author
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Toshikazu Takigawa, Jun-ichi Horinaka, and Ryosuke Shimizu
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010407 polymers ,Materials science ,Polymers and Plastics ,Hofmeister series ,Transition entropy ,Transition temperature ,Stress limit ,κ carrageenan ,Thermodynamics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Positive correlation ,Alkali metal ,01 natural sciences ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Colloid and Surface Chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,0210 nano-technology ,Sol-gel - Abstract
The sol-gel transition entropy is estimated by using a modified Clapeyron-type equation for κ-carrageenan hydrogel systems under load. The effect of alkali metal salts on the sol-gel transition behavior is also investigated. The transition temperature decreases with increasing compressional stress, while the transition entropy remains unchanged. Both the transition entropy and the transition temperature at the zero stress limit vary almost in accordance with the Hofmeister series, but the inversion occurs for RbCl and CsCl. For the gels examined, a positive correlation exists between the transition entropy and the transition temperature at the zero stress limit.
- Published
- 2017
12. Enabling high areal capacity for Co-free high voltage spinel materials in next-generation Li-ion batteries
- Author
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Yanbao Fu, Minghao Zhang, Yixuan Li, Ashley Cronk, Vince Battaglia, Weiliang Yao, Ryosuke Shimizu, Feng Zou, Yoon-Gyo Cho, Marshall A. Schroeder, Weikang Li, Ying Shirley Meng, and Arumugam Manthiram
- Subjects
Materials science ,Cobalt-free cathode ,LiNi0.5Mn1.5O4 ,Energy Engineering and Power Technology ,02 engineering and technology ,Electrolyte ,engineering.material ,010402 general chemistry ,01 natural sciences ,Ion ,law.invention ,Engineering ,Affordable and Clean Energy ,law ,Thick electrode ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Energy ,Renewable Energy, Sustainability and the Environment ,Spinel ,Full cell cycling ,High voltage ,021001 nanoscience & nanotechnology ,Engineering physics ,Cathode ,0104 chemical sciences ,Chemical Sciences ,Electrode ,engineering ,Degradation (geology) ,High voltage spinel ,0210 nano-technology ,Reduced cost - Abstract
The rapidly growing technological demand for lithium-ion batteries has prompted the development of novel cathode materials with high energy density, low cost, and improved safety. High voltage spinel, LiNi0.5Mn1.5O4 (LNMO), is one of the most promising candidates yet to be commercialized. The two primary obstacles for this material are the inferior electronic conductivity and fast capacity degradation in full cells due to the high operating voltage. By systematically addressing these limitations, we successfully develop a thick LNMO electrode with areal capacity loadings up to 3 mAh·cm−2. The optimized thick electrode is paired with a commercial graphite anode at both the coin cell and pouch cell level, achieving a full cell capacity retention as high as 72% and 78%, respectively, after 300 cycles. We attribute this superior cycling stability to careful optimizations of cell components and testing conditions, with a specific focus improving electronic conductivity and high voltage compatibility. These results suggest precise control of materials quality, electrode architecture and electrolyte optimization can soon support the development of a cobalt-free battery system based on a thick LNMO cathode (>4 mAh·cm2), which will eventually meet the needs of next-generation Li-ion batteries with reduced cost, improved safety, and assured sustainability.
- Published
- 2020
13. Correction to: Creep and solvent squeeze behavior of κ-carrageenan gels under compression
- Author
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Takuma Tanigawa, Toshikazu Takigawa, Koichi Yao, Jun-ichi Horinaka, and Ryosuke Shimizu
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Solvent ,Colloid and Surface Chemistry ,Materials science ,Polymers and Plastics ,Creep ,Materials Chemistry ,κ carrageenan ,Physical and Theoretical Chemistry ,Composite material ,Compression (physics) - Abstract
The author noticed that the published paper contained error. Unfortunately, Table 2 was incorrectly presented. Given in this paper is the correct table.
- Published
- 2019
14. Ternary blend polymer solar cells with wide-range light harvesting (Conference Presentation)
- Author
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Yasunari Tamai, Zakya H. Kafafi, Paul A. Lane, Hideo Ohkita, Ryosuke Shimizu, and Kwanghee Lee
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Amorphous silicon ,chemistry.chemical_classification ,Photocurrent ,Materials science ,business.industry ,Photovoltaic system ,Polymer ,Polymer solar cell ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Solar cell ,Optoelectronics ,Polymer blend ,business ,Ternary operation - Abstract
Polymer-based solar cells have made rapid progress in the last decade and are currently attracting a great deal of attention as a next-generation solar cell. Very recently, they have shown a power conversion efficiency (PCE) of more than 10%, which is comparable to that reported for amorphous silicon solar cells. However, it is still required to improve the photovoltaic performance furthermore for practical applications. In this talk, I will demonstrate ternary blend polymer solar cells, which are a new approach to improving the photocurrent generation. We have recently developed ternary blend polymer solar cells based on a wide-bandgap polymer, poly(3-hexylthiophene) (P3HT), a fullerene derivative (PCBM), and a near-IR dye molecule such as a silicon phthalocyanine derivative (SiPc). Such near-IR dye addition can easily expand the light-harvesting wavelength range up to the near-IR region, and hence can boost the photocurrent furthermore. I will demonstrate how molecular design of near-IR dye molecules can control the location in ternary blend solar cells to improve the photocurrent generation effectively. We also have fabricated ternary blend polymer solar cells based on a wide-bandgap polymer, a low-bandgap polymer, and PCBM. This two-donor polymer blend can also expand the light-harvesting wavelength and hence can boost the photocurrent effectively. Efficient exciton harvesting and charge collection can be designed by combining a wide-bandgap crystalline polymer and a low-bandgap amorphous polymer.
- Published
- 2017
15. Monolayer Study by VSFS: In Situ Response to Compression and Shear in a Contact
- Author
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C. Magnus Johnson, Mark W. Rutland, Ahmed Ghalgaoui, Saman Hosseinpour, Rubén Álvarez-Asencio, Clayton T. McKee, and Ryosuke Shimizu
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chemistry.chemical_classification ,education.field_of_study ,Materials science ,Population ,Analytical chemistry ,Surfaces and Interfaces ,Polymer ,Condensed Matter Physics ,Octadecyltrichlorosilane ,Shear rate ,Contact angle ,Shear (sheet metal) ,chemistry.chemical_compound ,chemistry ,Monolayer ,Electrochemistry ,General Materials Science ,Silicon oxide ,education ,Spectroscopy - Abstract
Self-assembled octadecyltrichlorosilane ((OTS), CH3(CH2)17SiCl3) layers on hydroxyl-terminated silicon oxide (SiO2) were prepared. The monolayers were characterized with atomic force microscopy (AFM) and contact angle measurements; their conformation was studied before, during, and after contact with a polymer (either PDMS or PTFE) surface using the vibrational sum frequency spectroscopy (VSFS) technique. During contact, the effect of pressure was studied for both polymer surfaces, but in the case of PTFE, the effect of shear rate on the contact was simultaneously studied. The VSFS response of the monolayers with pressure was almost entirely due to changes in the real area of contact with the polymer and therefore the Fresnel factors, whereas sliding caused disorder in the previously all-trans monolayer, as evidenced by a significant increase in the population of gauche defects.
- Published
- 2014
16. Analysis of Polyethylene Latex Particle Removal Mechanism on SiO2 Wafer Using Ultrasonic Spray Cleaning
- Author
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Tomomi Hikida, Ryoga Sawaki, Masanori Sato, Tatsuo Mori, Ryosuke Shimizu, Yuji Honda, and Yoshiyuki Seike
- Subjects
Jet (fluid) ,Materials science ,business.industry ,Adhesion ,Polyethylene ,Radiation ,Latex particle ,chemistry.chemical_compound ,Semiconductor ,chemistry ,Wafer ,Ultrasonic sensor ,Composite material ,business - Abstract
In single-wafer cleaning of semiconductor chips and flat panel displays, various cleaning methods tailored to the process, such as two-fluid spray cleaning, high-pressure jet spray cleaning, ultrasonic cleaning spray cleaning, and scrub cleaning have been proposed and put to practical use. In this study, Polyethylene Latex (PSL) particles 0.2 µm in diameter and 1 µm in diameter were electro-sprayed on the SiO2 The soil samples, and then cleaning efficiency were measured using two types of ultrasonic sprayers with frequencies of 1 MHz and 3 MHz confirmed. The soil samples are controlled for adhesion by deforming the PSL particles by heating the silicon wafer from 300K to 425K. From the experimental results, it was found that the is determined by factors other than the conventionally reported radiation flow in PSL particles. Figure 1
- Published
- 2019
17. Film Thickness Prediction of Poly-Silicon LPCVD Process with a Simplified Two-Step Surface Reaction Model
- Author
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Yukihiro Shimogaki, Ryosuke Shimizu, Masaaki Ogino, Mitsuo Koshi, and Kimihisa Kaneko
- Subjects
Materials science ,Chemical engineering ,Silicon ,chemistry ,Scientific method ,Two step ,chemistry.chemical_element ,Chemical vapor deposition ,Surface reaction ,Electronic, Optical and Magnetic Materials - Published
- 2013
18. Cathodic polarization curves of the oxygen reduction reaction on various structural materials of boiling water reactors in high temperature–high purity water
- Author
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Nobuyoshi Hara, Ota Nobuyuki, Ryosuke Shimizu, Masahiko Tachibana, Yoichi Wada, and Kazushige Ishida
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Nuclear and High Energy Physics ,Structural material ,Materials science ,Alloy ,Inorganic chemistry ,engineering.material ,Redox ,Coolant ,Anode ,Nuclear Energy and Engineering ,Boiling ,engineering ,Boiling water reactor ,Stress corrosion cracking - Abstract
Cathodic polarization curves of the O2 reduction reaction were measured by using electrodes made from typical structural materials of boiling water reactors (BWRs) to evaluate the effects of kind of material on the electrochemical corrosion potential (ECP) calculation. To estimate ECPs at any region in the BWRs on the basis of the BWR environmental conditions, anodic and cathodic polarization curves should be obtained in advance under relevant conditions. The concentration of oxidants such as O2 and H2O2 in coolant changes depending on the region in which they exist. As well, reduction reaction rates might differ depending on the kind of materials. In this work, the cathodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in high purity water at 553 K with different O2 concentrations and compared with those of type 304 SS (304 SS). The results showed that the cathodic polarization curves differed depending on the kind of materials at the activation-controlled region....
- Published
- 2012
19. Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature – high purity water
- Author
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Ota Nobuyuki, Masahiko Tachibana, Nobuyoshi Hara, Ryosuke Shimizu, Kazushige Ishida, and Yoichi Wada
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Nuclear and High Energy Physics ,Materials science ,Metallurgy ,Alloy ,Analytical chemistry ,chemistry.chemical_element ,engineering.material ,Corrosion ,Nickel ,Chromium ,Nuclear Energy and Engineering ,chemistry ,Boiling ,engineering ,Boiling water reactor ,Polarization (electrochemistry) ,Dissolution - Abstract
In order to examine the anodic polarization characteristics of typical structural materials of boiling water reactors (BWRs), the anodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in deaerated high purity water at 553 K using the previously reported measurement method which was confirmed suitable for high temperature – high purity water. In order to specify which constituent element determines the dissolution characteristics of these materials, the anodic polarization curves of pure iron, pure nickel, and pure chromium were also surveyed. The anodic polarization curve of 316L SS was determined to have active, passive, and transpassive states which were the same as type 304 SS (304 SS) showed. But, Alloy 182 had different polarization characteristics especially near the corrosion potential as it had no active state. From comparison results of the polarization characteristics of these materials and their constituent elements, the corrosion characteristics of these...
- Published
- 2012
20. Analysis of Supercharged HCCI Combustion Using a Blended Fuel
- Author
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Hideo Shoji, Koji Yoshida, Akira Iijima, and Ryosuke Shimizu
- Subjects
Materials science ,business.industry ,Hcci combustion ,General Medicine ,Process engineering ,business - Published
- 2011
21. 800-nm Band Cross-Polarized Photon Pair Source Using Type-II Parametric Down-Conversion in Periodically Poled Lithium Niobate
- Author
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Shigehiro Nagano, Ryosuke Shimizu, Koji Suizu, Keiichi Edamatsu, Hiromasa Ito, and Yohei Sugiura
- Subjects
Quasi-phase-matching ,Materials science ,Photon ,Physics and Astronomy (miscellaneous) ,business.industry ,Lithium niobate ,General Engineering ,Physics::Optics ,General Physics and Astronomy ,Avalanche photodiode ,chemistry.chemical_compound ,Optics ,Spontaneous parametric down-conversion ,chemistry ,business ,Wavelength band ,Production rate ,Parametric statistics - Abstract
We report a high-efficiency source of cross-polarized photon pairs via type-II quasi-phase matched spontaneous parametric down-conversion using periodically poled lithium niobate (PPLN). The photon pairs are generated from the PPLN in a fifth-order quasi-phase matching condition around 800 nm, which matches the wavelength band of efficient Si avalanche photodiodes. We obtained the photon-pair production rate of 6.8×105 s-1 mW-1.
- Published
- 2007
22. Stress Characterization of Si by a Scanning Near-Field Optical Raman Microscope with Spatial Resolution and with Penetration Depth at the Nanometer Level, using Resonant Raman Scattering
- Author
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Masataka Murakami, Masanobu Yoshikawa, Ryuichi Sugie, Ryosuke Shimizu, Hideyuki Ishida, and Keiko Matsuda
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Materials science ,Physics and Astronomy (miscellaneous) ,Silicon ,business.industry ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Near and far field ,symbols.namesake ,Optics ,X-ray Raman scattering ,chemistry ,symbols ,Raman microscope ,Coherent anti-Stokes Raman spectroscopy ,Penetration depth ,business ,Raman spectroscopy ,Raman scattering - Abstract
We have developed a new tapping mode-scanning near-field optical Raman microscope (SNORM) with a caved and pyramidical probe, using resonant Raman scattering and measured the stress distribution of very-large-scale integration (VLSI) standards made of the silicon dioxide film and Si. It has been found that compressive stresses of about 0.69 GPa/cm2 are concentrated on the corner of the area uncovered by silicon dioxide. The SNORM we developed has at least the spatial resolution of less than 250 nm and is a useful tool to measure image of stresses in Si devices within a short time and with a penetration depth of 5 nm.
- Published
- 2006
23. Flattening of micro-structured Si surfaces by hydrogen annealing
- Author
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Ryosuke Shimizu, Koichi Sudoh, Hitoshi Kuribayashi, Reiko Hiruta, and Hiroshi Iwasaki
- Subjects
Materials science ,Hydrogen ,Silicon ,Annealing (metallurgy) ,Metallurgy ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Microstructure ,Atomic units ,Flattening ,Surfaces, Coatings and Films ,chemistry ,Trench ,Wafer ,Composite material - Abstract
We report atomic scale flattening of surfaces of microstructures formed on Si wafers by furnace annealing. To avoid thermal deformation of the fabricated structures, advantage was taken of hydrogen annealing, which enables us to decrease the relaxation rate of Si surfaces due to surface hydrogenation. We examined cross-sectional shape and sidewall morphology of 3 μm deep trenches on Si(0 0 1) substrates after annealing at 1000 °C under various H2 pressures of 40–760 Torr. We successfully formed Si trenches with flat surfaces composed of terraces and steps while preserving the designed trench profile by increasing H2 pressure to 760 Torr.
- Published
- 2006
24. Shape transformation of silicon trenches during hydrogen annealing
- Author
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Reiko Hiruta, Ryosuke Shimizu, Koichi Sudoh, Hiroshi Iwasaki, and Hitoshi Kuribayashi
- Subjects
Surface diffusion ,Materials science ,Hydrogen ,Silicon ,Annealing (metallurgy) ,Scanning electron microscope ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Thermal treatment ,Surface finish ,Condensed Matter Physics ,Computer Science::Other ,Physics::Geophysics ,Surfaces, Coatings and Films ,Condensed Matter::Materials Science ,chemistry ,Trench - Abstract
Shape transformation of silicon trenches during annealing at high temperatures in a hydrogen ambient was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By SEM observation of the trench profiles, we found that the rate of shape transformation increases with decreasing hydrogen pressure. Performing the simulation based on a continuum surface model, we show that the shape transformation during annealing in a hydrogen ambient is due to surface self-diffusion. By quantitative comparison of the results between the experiment and simulation, we estimated the diffusion coefficients. The obtained activation energy for surface diffusion under a hydrogen pressure of 40 Torr was much higher than that measured under ultrahigh-vacuum conditions. Furthermore, it was found by AFM observation of the trench sidewall surfaces that, during the thermal treatment, the large roughness of the as-etched trench sidewall surface decreased significantly due to surface self-diffusion of silicon atoms, resulting structures with atomically flat terraces and steps.
- Published
- 2003
25. 103 Mechanical Properties of Laser Welded Austempered Spheroidal Graphite Cast Iron
- Author
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Shinichi Sekiguchi, Kenichi Maniwa, Fumio Shibata, Ryosuke Shimizu, Tetsu Munakata, and Yusuke Sano
- Subjects
Materials science ,law ,Metallurgy ,engineering ,Cast iron ,Graphite ,Welding ,engineering.material ,Composite material ,Laser ,law.invention - Published
- 2015
26. Widely tunable single photon source with high purity at telecom wavelength
- Author
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Masahide Sasaki, Rui-Bo Jin, Hugo Benichi, Ryosuke Shimizu, and Kentaro Wakui
- Subjects
Quantum optics ,Quantum Physics ,Photons ,Photon ,Materials science ,business.industry ,FOS: Physical sciences ,Second-harmonic generation ,Equipment Design ,Atomic and Molecular Physics, and Optics ,Equipment Failure Analysis ,Wavelength ,Optics ,Spontaneous parametric down-conversion ,Single-photon source ,Telecommunications ,Computer-Aided Design ,Quantum Physics (quant-ph) ,business ,Radiant intensity ,Lighting ,Optics (physics.optics) ,Spectral purity ,Physics - Optics - Abstract
We theoretically and experimentally investigate the spectral tunability and purity of photon pairs generated from spontaneous parametric down conversion in periodically poled $\mathrm{KTiOPO_4}$ crystal with group-velocity matching condition. The numerical simulation predicts that the purity of joint spectral intensity ($P_{JSI}$) and the purity of joint spectral amplitude ($P_{JSA}$) can be kept higher than 0.98 and 0.81, respectively, when the wavelength is tuned from 1460 nm to 1675 nm, which covers the S-, C-, L-, and U-band in telecommunication wavelengths. We also directly measured the joint spectral intensity at 1565 nm, 1584 nm and 1565 nm, yielding $P_{JSI}$ of 0.989, 0.983 and 0.958, respectively. Such a photon source is useful for quantum information and communication systems., 8 pages, 5 figures
- Published
- 2013
27. Mechanism of hole inlet closure in shape transformation of hole arrays on Si(001) substrates by hydrogen annealing
- Author
-
Koichi Sudoh, Hitoshi Kuribayashi, Ryosuke Shimizu, and Reiko Hiruta
- Subjects
Azimuth ,geography ,Materials science ,geography.geographical_feature_category ,Annealing (metallurgy) ,Metallurgy ,Pattern formation ,Geometry ,Anisotropy ,Mirror symmetry ,Microstructure ,Inlet ,Surface energy - Abstract
We investigated the process of the hole inlet closure in surface-diffusion-driven transformation of arrays of high-aspect-ratio holes on Si(001) substrates. The inlet gradually shrinks while keeping the circular shape because of lateral bulging of the inlet surface. We observed complicated top view morphologies reflecting the four-fold symmetry of the Si(001) surface on the inlet surface. Large {111} and {113} facets are formed in the four equivalent azimuths of the [110], while corrugated patterns arise in the four equivalent azimuths of the [100]. Atomic force microscopy observations reveal that the corrugated pattern is composed of three types of small facets, namely, {110} and two {113} in relation of the mirror symmetry. The corrugated pattern formation is due to the geometrical restriction that there is no stable facet between (001) and (010) in the [010] azimuth. The observed morphological evolution is interpreted as surface-diffusion-driven transformation under constraint of the anisotropic surface energy of Si.
- Published
- 2011
28. Development of a UV-Laser Excited Micro-Raman Spectrometer
- Author
-
Shigeto Takeda, Ryosuke Shimizu, Takahiro Kasuya, Hisako Urabe, and Motowo Tsukakoshi
- Subjects
Materials science ,Optics ,Spectrometer ,Micro raman ,business.industry ,Excited state ,Uv laser ,High spatial resolution ,business - Published
- 1992
29. Measurement of the cross-Kerr nonlinearity induced by a single-photon-level coherent pulse in a photonic crystal fiber
- Author
-
Nobuyuki Matsuda, Ryosuke Shimizu, Yasuyoshi Mitsumori, Hideo Kosaka, Keiichi Edamatsu, and Alexander Lvovsky
- Subjects
Materials science ,business.industry ,Single-mode optical fiber ,Physics::Optics ,Polarization-maintaining optical fiber ,Microstructured optical fiber ,Graded-index fiber ,Optics ,Optoelectronics ,Dispersion-shifted fiber ,business ,Plastic optical fiber ,Photonic crystal ,Photonic-crystal fiber - Abstract
We demonstrate the first observation of the cross‐Kerr nonlinearity induced by a single‐photon‐level coherent optical pulse in a photonic crystal fiber. Taking advantage of large nonlinearity and managed dispersion of the optical fiber, we have successfully measured very small (10−7) conditional phase shifts.
- Published
- 2009
30. Temperature dependence of blue light-induced near-infrared absorption of ferroelectric crystals
- Author
-
Keiichi Edamatsu, A. Shoji, Shigehiro Nagano, Ryosuke Shimizu, and Koji Suizu
- Subjects
Optics ,Materials science ,business.industry ,Analytical chemistry ,Nonlinear optics ,Infrared spectroscopy ,business ,Absorption (electromagnetic radiation) ,Ferroelectricity ,Ferroelectric crystal ,Stoichiometry ,Blue light ,Near infrared absorption - Abstract
We studied blue light-induced near-infrared absorption (BLINIRA) and its temperature dependence in ferroelectric crystals, i.e., MgO-doped stoichiometric-LiNbO3, congruent-LiNbO3, MgO-doped stoichiometric-LiTaO3, and stoichiometric-LiTaO3. We found the BLINIRA decreased with the increase of temperature.
- Published
- 2008
31. Generation of cross-polarized photon pairs in a 800-nm band via Type II parametric down-conversion using a periodically poled Lithium Niobate
- Author
-
Ryosuke Shimizu, Keiichi Edamatsu, Y. Sugiura, Hiromasa Ito, Shigehiro Nagano, and Koji Suizu
- Subjects
Materials science ,Photon ,business.industry ,Lithium niobate ,Physics::Optics ,Avalanche photodiode ,Coincidence ,chemistry.chemical_compound ,Optics ,Spontaneous parametric down-conversion ,chemistry ,Periodic poling ,Optoelectronics ,business ,Wavelength band ,Parametric statistics - Abstract
We have developed a high-efficiency source of cross-polarized photon pairs via type-II quasi-phase matched spontaneous parametric down-conversion using periodically poled lithium niobate (PPLN). The photon pairs are generated from the PPLN in fifth-order quasi-phase matched condition around 800 nm, which matches the wavelength band of efficient Si avalanche photodiodes. We obtained 25,000 coincidence counts sec-1mW-1of the photon pairs.
- Published
- 2007
32. Deposition Uniformity Control in a Commercial Scale HTO-CVD Reactor
- Author
-
Yukihiro Shimogaki, Shigeru Sakai, Masaaki Ogino, and Ryosuke Shimizu
- Subjects
Materials science ,Hybrid physical-chemical vapor deposition ,Plasma-enhanced chemical vapor deposition ,Ion plating ,Wafer ,Chemical vapor deposition ,Combustion chemical vapor deposition ,Composite material ,Deposition (chemistry) ,Pulsed laser deposition - Abstract
High-temperature silicon dioxide chemical vapor deposition (HTOCVD), using SiH2Cl2 and N2O, can realize dense and conformal oxide film, not only on large size silicon wafers, but even inside of microscopic silicon trenches, at high-temperature around 800°C.In this work, we investigated the kinetics of HTOCVD using a commercial scale low pressure (LP) CVD reactor, focusing on the correlation between deposition rate and surface-to-volume ratio (S/V ratio), which is a specific surface area of substrate wafer divided by the space volume between two adjacent wafers. We also investigated the deposition rate profile on wafers, and along the axial direction of the reactor near the region where one, two or three substrate wafers are extracted from the quartz holder. The deposition rate profiles on wafer characteristically change from skillet-like to pancake-like, according to the increase of wafer spacing. The influence on the deposition rate of wafer spacing spreads to ranges not only downstream, but also upstream in the gas flow. These experimental results strongly suggest that in the HTOCVD gas-phase reactions through intermediate states of active species contribute to deposition reaction as well as direct deposition reaction of source gases on Si surface.
- Published
- 2007
33. Nano-scale Observation of Si Trench Sidewall Surface Morphology by AFM Technology
- Author
-
Hitoshi Kuribayashi, Reiko Hiruta, and Ryosuke Shimizu
- Subjects
Surface (mathematics) ,Cantilever ,Morphology (linguistics) ,Materials science ,Atomic force microscopy ,law ,Trench ,Substrate (electronics) ,Carbon nanotube ,Composite material ,Nanoscopic scale ,law.invention - Abstract
We have developed an atomic force microscopy (AFM) observation technique with which Si trench sidewall surface can be scanned with the tip of cantilever to investigate its nano-scale morphologies. By developing a new technique of cleaving the substrate at the center of a micron-sized trench along its longitudinal direction [011], the sidewall nano-scale morphology of the trench could be observed with the AFM technique. By comparing of cross sections of the images, we also investigated the difference between Si and carbon nanotube (CNT) tips for the AFM observations. According to the results, the CNT tip proved to show a superior signal-to-noise (S/N) ratio compared with the Si tip. The CNT tip enables us to observe the step patterns of the sidewalls of micron-sized trench structures in the various phases of hydrogen annealing.
- Published
- 2007
34. Spectral properties of broadband biphotons generated from PPMgSLT under a type-II phase-matching condition
- Author
-
Nandan S. Bisht and Ryosuke Shimizu
- Subjects
Quantum optics ,Materials science ,Spectral power distribution ,business.industry ,Physics::Optics ,Statistical and Nonlinear Physics ,Atomic and Molecular Physics, and Optics ,Interferometry ,Optics ,Interference (communication) ,Picosecond ,Spectral width ,Optoelectronics ,Physics::Chemical Physics ,business ,Spectroscopy ,Radiant intensity - Abstract
We report the spectral properties of broadband biphotons generated by pulsed type-II spontaneous parametric down-conversion based on a periodically poled MgO-doped stoichiometric LiTaO3 (PPMgSLT). Spectroscopic and interferometric measurements were used to characterize the biphoton source. For the spectroscopic measurements, we used conventional spectroscopy and joint spectral intensity measurements. For the interferometric measurements, sum- and difference-frequency two-photon interference experiments were performed to estimate the spectral correlation and to ensure the broadband nature of biphotons, respectively. When using a picosecond Ti:sapphire as a pump source, the spectral width of biphotons was over 40 nm. Finally, we demonstrated the relationship between the two-photon interference visibility and the symmetricity of the joint spectral distribution.
- Published
- 2015
35. Time Evolution of Nano-scale Morphology of Silicon Microstructure Surfaces in the Early Phase of Hydrogen Annealing
- Author
-
Hiroshi Iwasaki, Reiko Hiruta, Koichi Sudoh, Ryosuke Shimizu, and Hitoshi Kuribayashi
- Subjects
chemistry.chemical_compound ,Materials science ,Morphology (linguistics) ,chemistry ,Chemical engineering ,Hydrogen ,Silicon ,Torr ,Trench ,Oxide ,chemistry.chemical_element ,Microstructure ,Annealing (glass) - Abstract
We have examined how the morphology of the trench sidewall evolves in the early phase of hydrogen annealing under the two conditions of hydrogen pressures. A distinguished result was obtained concerning the sidewall surface morphology after 30 s annealing at 1000 °C under 760 Torr hydrogen ambient. The evanescence of chemical Si dioxide formed by RCA cleaning process was clearly observed to initiate in various places on the surface. And in the area without chemical oxide, the appearance of atomic steps was also observed. In contrast under 40 Torr hydrogen ambient, the chemical oxide was completely removed even after 30 s annealing. Our observation shows that not only the rate of trench shape transformation but also the rate of removal of oxide films decreases with increasing hydrogen pressure.
- Published
- 2006
36. 407 Effects of Cr and Ni Contents in Spheroidal Graphite Cast Iron and Mild Steel Welded Joints using Insert Metals
- Author
-
Yuki Saito, Ryosuke Shimizu, Shinichi Sekiguchi, Fumio Shibata, and Hiromasa Takahashi
- Subjects
Insert (composites) ,Materials science ,law ,Metallurgy ,engineering ,Cast iron ,Welding ,Graphite ,Composite material ,engineering.material ,law.invention - Published
- 2013
37. Phenomenological and Elementary Reaction Analysis of Poly-crystalline Silicon CVD Process
- Author
-
Mitsuo Koshi, Tadashi Januma, Masakazu Sugiyama, Ryosuke Shimizu, Masaaki Ogino, and Yukihiro Shimogaki
- Subjects
Chemical species ,Materials science ,Chemical engineering ,Silicon ,chemistry ,Diffusion ,Metallurgy ,Elementary reaction ,chemistry.chemical_element ,Deposition (phase transition) ,Wafer ,Chemical vapor deposition ,Chemical reaction - Abstract
Thickness uniformities of poly-crystalline silicon thin films, deposited by a commercial LPCVD reactor, were investigated through a phenomenological and elementary reaction analysis. To understand the deposition rate and its profile in radius direction of ø 6”h silicon wafer, concentration distributions of film precursors were examined by solving basic diffusion equations of film precursors in the CVD system. The experimental thickness distribution can be simulated very well with the solution by optimizing η, the sticking probabilities of the precursors. While most of the silicon deposition was made by source precursor (mono-silane, SiH4), two kinds of intermediate species with sticking probabilities of 5X10-2 and 7X10-4 were found to contribute the deposition. Subsequently, elementary chemical reaction analysis of poly-crystalline silicon CVD process was performed using ChemKinTM and two chemical species, SiH2 and Si2H6, were identified as the possible candidates for the intermediate species.
- Published
- 2002
38. 220202 Influence of Equivalence Ratio of DME on HCCI Combustion using a Blended Fuel
- Author
-
Koji Yoshida, Shusuke Inaba, Ryosuke Shimizu, Kiyoshi Komatu, Akira Iijima, and Hideo Shoji
- Subjects
Materials science ,Hcci combustion ,Thermodynamics ,Equivalence ratio - Published
- 2011
39. 456 A Study of Supercharged HCCI Engine by using Mixing Fuel (the 1^<st> report) : Influence of DME and Methane
- Author
-
Hideo Shoji, Shusuke Inaba, Ryosuke Shimizu, Akira Iijima, and Kiyoshi Komatsu
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,business.industry ,Homogeneous charge compression ignition ,Process engineering ,business ,Automotive engineering ,Methane ,Mixing (physics) - Published
- 2010
40. Nanolithography Developed Through Electron Beam Induced Surface Reaction
- Author
-
K. Ogai, Ryosuke Shimizu, Yukinori Ochiai, Y. Ohnishi, Masakazu Baba, S. Matsui, Shoko Manako, Jun-ichi Fujita, Y. Kimura, and Heiji Watanabe
- Subjects
Microscope ,Materials science ,Scanning electron microscope ,business.industry ,chemistry.chemical_element ,Tungsten ,law.invention ,Nanolithography ,Resist ,chemistry ,law ,Etching (microfabrication) ,Optoelectronics ,Dry etching ,Scanning tunneling microscope ,business - Abstract
Nanolithography has been studied by using electron beam technology. Ten-nm linewidth PMMA resist patterns have been demonstrated by 50 kV scanning electron beam. The self-developing properties of a AlF3 doped LiF inorganic resist under a scanning electron beam irradiation with energy of 20–50 keV have been studied for sub-10 nm lithography. By optimizing the inorganic resist film quality, 5 nm linewidth patterns with 60 nm periodicity were directly delineated under a 30 keV electron beam. Another approach for nanolithography using electron beam holography has been proposed. Line and dot patterns with 100 nm periodicity were exposed on PMMA resist by electron beam holography with thermal field emitter gun and an electron biprism. Subsequent atomic force microscope observation has confirmed that both patterns are successfully fabricated. This technique allows us to produce nanoscale periodic patterns simultaneously. The selective atomic desorption of Cl atoms adsorbed on a Si (111) 7×7 surface has been studied by field evaporation using a scanning tunneling microscope (STM). The STM tip is placed on the adsorbed Cl on the surface, and pulse voltage was applied. This results in selective atomic desorption of Cl.
- Published
- 1995
41. G060084 An Analysis of Supercharged HCCI Combustion using a Two-component Fuel Blend
- Author
-
Kiyoshi Komatsu, Kouji Yoshida, Shusuke Inaba, Ryosuke Shimizu, Mitsuo Asanuma, Hideo Shoji, and Akira Iijima
- Subjects
Materials science ,business.industry ,Component (UML) ,Hcci combustion ,Process engineering ,business - Published
- 2011
42. Efficient Up-Conversion Detection of 1550 nm Photons Using Bulk Periodically-Poled LiNbO3
- Author
-
Ryosuke Shimizu, Keiichi Edamatsu, Shigehiro Nagano, Atsushi Syouji, and Koji Suizu
- Subjects
Photon ,Materials science ,Physics::Instrumentation and Detectors ,business.industry ,Dark count rate ,Photon detector ,General Engineering ,Physics::Optics ,General Physics and Astronomy ,Internal conversion (chemistry) ,Optics ,Optoelectronics ,Up conversion ,business ,Photon detection - Abstract
We demonstrate efficient up-conversion detection of photons at 1550 nm utilizing bulk periodically-poled LiNbO3 (PPLN) and nanosecond-pulsed pumping. An internal conversion efficiency of 96% and an overall photon detection efficiency of 19% including the efficiency of a visible photon detector were achieved with a low dark count rate.
- Published
- 2010
43. All-optical phase modulations in a silicon wire waveguide at ultralow light levels
- Author
-
Nobuyuki Matsuda, Hiroyuki Yokoyama, Koji Yamada, Tai Tsuchizawa, Keiichi Edamatsu, Yasuyoshi Mitsumori, Hideo Kosaka, Hiroshi Fukuda, Seiichi Itabashi, Ryosuke Shimizu, Aya Sato, and Toshifumi Watanabe
- Subjects
Materials science ,Kerr effect ,Physics and Astronomy (miscellaneous) ,Silicon ,business.industry ,Cross-phase modulation ,Phase (waves) ,chemistry.chemical_element ,Waveguide (optics) ,Optics ,chemistry ,Dispersion (optics) ,Optoelectronics ,business ,Phase conjugation ,Phase modulation - Abstract
Cross-phase modulation(XPM) in a silicon wire waveguide at 1.55 μ m telecom band was studied down to ultralow light levels. In the low-power regime, we found that free-carrier dispersion as well as the optical Kerr effect contributes to the XPM. Possible mechanisms of the low-power XPM are discussed.
- Published
- 2009
44. Predictable Simple Reaction Model for Poly-Silicon LPCVD Process
- Author
-
Mitsuo Koshi, Masaaki Ogino, Kimihisa Kaneko, Yukihiro Shimogaki, and Ryosuke Shimizu
- Subjects
Materials science ,Silicon ,chemistry ,Chemical engineering ,Simple (abstract algebra) ,Reaction model ,Scientific method ,chemistry.chemical_element ,Chemical vapor deposition - Abstract
Poly-silicon deposition rate profiles on silicon wafers in several temperatures around 873 K along axial direction in commercial low-pressure chemical vapor deposition (LPCVD) reactor were investigated by both experiments and numerical simulations considering coupled computational fluid dynamics (CFD) and chemical reactions. While the chemical reaction processes of poly-silicon film deposition is a complicated system with a huge number of elementary reactions, we could successfully simulate the experimental results with a simplified 2-step surface reaction model of SiH4. Simulated film deposition rate profiles along the axial direction of reactor were in good agreement with experimental results, and the 2-step reaction model was proved to be a good tool for the numerical simulation of poly-silicon deposition process in commercial reactor.
- Published
- 2009
45. Generation of Cross-Polarized Photon Pairs via Type-II Third-Order Quasi-Phase Matched Parametric Down-Conversion
- Author
-
Koji Suizu, Hiromasa Ito, Ryosuke Shimizu, Atsushi Syouji, Shigehiro Nagano, and Keiichi Edamatsu
- Subjects
Photon ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Lithium niobate ,General Engineering ,Phase (waves) ,General Physics and Astronomy ,Third order ,chemistry.chemical_compound ,Optics ,Spontaneous parametric down-conversion ,chemistry ,Atomic physics ,business ,Production rate ,Parametric statistics - Abstract
We have developed a high-efficiency source of cross-polarized photon pairs generated via type-II spontaneous parametric down-conversion using periodically poled lithium niobate (PPLN). The photon pairs are generated from bulk PPLN under third-order quasi-phase-matched conditions around 800 nm. We achieved a photon-pair production rate of N=1.95×106 s-1mW-1.
- Published
- 2009
46. Numerical Study on Shape Transformation of Silicon Trenches by High-Temperature Hydrogen Annealing
- Author
-
Ryosuke Shimizu, Reiko Hiruta, Hiroshi Iwasaki, Hitoshi Kuribayashi, and Koichi Sudoh
- Subjects
Surface diffusion ,Hydrogen annealing ,Mass transport ,Materials science ,Silicon ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Shape transformation ,Condensed Matter::Materials Science ,Crystallography ,chemistry ,Chemical physics ,Trench - Abstract
We have studied shape transformation of micron-sized trenches on Si substrates during high temperature hydrogen annealing, performing numerical simulations based on Mullins' theory. We have considered evaporation-condensation and surface diffusion as mass transport mechanisms causing shape transformation. The simulation allowing only surface diffusion reproduces well the observed micron-scale aspects of shape transformation by hydrogen annealing at 1000–1150°C.
- Published
- 2004
47. Exciton Luminescence in TlBr and TlCl
- Author
-
Takao Koda, Ryosuke Shimizu, and Toshiaki Murahashi
- Subjects
Condensed Matter::Materials Science ,Materials science ,Phonon ,Impurity ,Exciton ,General Physics and Astronomy ,Halide ,Spontaneous emission ,Emission spectrum ,Atomic physics ,Luminescence ,Resonance (particle physics) - Abstract
luminescence and its excitation spectra are investigated on TlBr and TlCl single crystals. The luminescence spectra of both halides consist of three characteristic emissions, a broad emission band and two kinds of narrow emission lines. The highest energy emission line is ascribed to the resonance emission of the direct exciton. The low energy threshold of the excitation spectra is interpreted as the contribution from the indirect interband transition, In TlBr, an oscillatory phonon structure is observed above this threshold, from which the indirect-exciton energy is estimated to be 2.630 ±0.005 eV. A similar edge in TlCl is supposed to lie around 3.20 eV. The sharp emission lines appearing below this indirect edge are attributable to the radiative recombination of the indirect exciton bound to some impurities. Discussions are presented on the radiative decay of these direct and indirect excitons in thallous halides.
- Published
- 1974
48. Electroreflectance of TlCl and TlBr
- Author
-
Takao Koda and Ryosuke Shimizu
- Subjects
Materials science ,General Physics and Astronomy - Published
- 1975
49. The Decay Mechanism of Hot Indirect Excitons in TlBr
- Author
-
Takao Koda and Ryosuke Shimizu
- Subjects
Materials science ,Chemical physics ,Exciton ,General Physics and Astronomy ,Mechanism (sociology) - Published
- 1974
50. Indirect Edge of TlBr as Observed in the Luminescence Excitation Spectra
- Author
-
Toshiaki Murahashi, Ryosuke Shimizu, and Takao Koda
- Subjects
Materials science ,Excitation spectra ,General Physics and Astronomy ,Edge (geometry) ,Luminescence ,Molecular physics - Published
- 1972
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