研究者詳細 - 原田　俊太

論文 - 原田　俊太

分割表示 203 件中 41 - 60 件目／全件表示 >>

High fracture toughness AlN achieved by addition of AlN whiskers and tape-casting 査読有り Open Access

Shimizu, H; Kondo, N; Shimamura, A; Hotta, M; Harada, S; Ujihara, T; Ohnishi, Y

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 130 巻 ( 1 ) 頁： 195 - 198 2022年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Ceramic Society of Japan

Aluminum nitride (AlN) possesses excellent thermal conductivity and electrical resistivity, which makes it an ideal candidate for high-power, high-speed integrated circuit substrates. Its low fracture toughness requires the manufacturing of thicker substrates. However, this leads to degraded heat dissipation performance. Herein, we investigated a new strategy, combining the addition of AlN whiskers and tape-casting, to overcome the low fracture toughness disadvantage. The sintered AlN with AlN whiskers addition induced the formation of a highly anisotropic microstructure with aligned rod-like grains, effectively enhancing the fracture toughness to 6.7MPam1/2, while maintaining thermal conductivity but degrading strength.

DOI： 10.2109/jcersj2.21143

Polarized light observation of semiconductor wafers for power devices

Murayama K., Mizutani S., Mizutani Y., Harada S.

2022 IEEE International Meeting for Future of Electron Devices, Kansai, IMFEDK 2022 2022年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：2022 IEEE International Meeting for Future of Electron Devices, Kansai, IMFEDK 2022

Polarized light observation is one of the promising methods for the non-destructive characterization of semiconductor wafers for power devices. We have visualized the distribution of defects in SiC wafers by birefringence imaging.

DOI： 10.1109/IMFEDK56875.2022.9975432

Scopus

シミュレーションに基づく結晶成長プロセスインフォマティクス

沓掛健太朗, 角岡洋介, 郁万成, 黨一帆, 原田俊太, 宇治原徹

日本結晶成長学会誌 49 巻 ( 1 ) 頁： n/a 2022年

Association between Achilles Tendon Softness and Atherosclerotic Cardiovascular Disease in Patients with Familial Hypercholesterolemia

Michikura, M; Ogura, M; Hori, M; Matsuki, K; Makino, H; Hosoda, K; Harada-Shiba, M

JOURNAL OF ATHEROSCLEROSIS AND THROMBOSIS 29 巻 ( 11 ) 頁： 1603 - 1612 2022年

Immobilization of partial dislocations bounding double Shockley stacking faults in 4H-SiC observed by <i>in situ</i> synchrotron X-ray topography 査読有り

Fujie, F; Harada, S; Suo, H; Raghothamachar, B; Dudley, M; Hanada, K; Koizumi, H; Kato, T; Tagawa, M; Ujihara, T

MATERIALIA 20 巻頁： 101246 2021年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materialia

The expansion of double Shockley stacking faults (DSFs) in an n-type 4H-SiC substrate with a nitrogen concentration of 3.9 × 1019 cm−3 was investigated using in situ synchrotron X-ray topography. DSF expansion was observed to be suppressed and immobilized above 1590 K, along with the partial dislocation (PD) shape being changed from a straight to zig-zag configuration. For a different heating process (higher heating rate), the PDs could continue to expand, even above 1590 K. Ex situ topography experiments revealed that the DSFs close to the specimen surface expanded widely, although those expanding toward the specimen interior became immobile. One possible mechanism for this immobilization was proposed, where the core structural changes from a Si-core to the C-core by non-conservative motion induced by the interaction between the PDs and point defects (C interstitials).

DOI： 10.1016/j.mtla.2021.101246

Web of Science

Scopus

Surface relaxation and photoelectric absorption effects on synchrotron X-ray topographic images of dislocations lying on the basal plane in off-axis 4H-SiC crystals 査読有り Open Access

Ailihumaer, T; Peng, HY; Fujie, F; Raghothamachar, B; Dudley, M; Harada, S; Ujihara, T

MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS 271 巻頁： 115281 2021年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Science and Engineering: B

A more sophisticated simulation model is developed based on the principle of ray-tracing to simulate the grazing-incidence synchrotron X-ray topographic contrast of dislocations lying on the basal plane including basal plane dislocations and deflected threading screw and mixed dislocations in off-axis 4H-SiC crystals. The model incorporates effects of surface relaxation as well as the photoelectric absorption to predict dislocation contrast. Compared to conventional ray-tracing images, surface relaxation effects dominate dislocation contrast for diffraction near the crystal surface. The simulated dislocation contrast gradually weakens with increasing depth of the diffracted beam position within the crystal due to photoelectric absorption. The distinctive features of the net simulated dislocation images obtained by aggregating through the effective penetration depth correlate well with contrast features observed on the experimental topographic images. Depth analysis reveals that in some cases the diffracted X-rays from regions below the dislocation can contribute additional contrast features previously not considered.

DOI： 10.1016/j.mseb.2021.115281

Web of Science

Scopus

混合ガウスモデルを用いた浮遊帯域溶融法における融液状態のダイナミクス推定

大前遼, 炭谷翔悟, 土佐祐介, 原田俊太

応用物理学会学術講演会講演予稿集 2021.2 巻 ( 0 ) 頁： 3410 - 3410 2021年8月

Two-Step Nanoparticle Crystallization via DNA-Guided Self-Assembly and the Nonequilibrium Dehydration Process 査読有り Open Access

Sumi, H; Ohta, N; Sekiguchi, H; Harada, S; Ujihara, T; Tsukamoto, K; Tagawa, M

CRYSTAL GROWTH & DESIGN 21 巻 ( 8 ) 頁： 4506 - 4515 2021年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Crystal Growth and Design

DNA strands are powerful tools as ligand molecules that bind nanoparticles to each other via programmable self-assembly for colloidal crystallization. We found that hydrated DNA-functionalized nanoparticle (DNA-NP) superlattices with a properly controlled volume fraction and spatial arrangement of nanoparticles successfully maintained their crystallinity even after dehydration, which involves drastic contraction. A detailed study of the structural changes was performed for the self-assembled DNA-NP sample using small-angle X-ray scattering (SAXS) after dehydration. Then, an optimal volume fraction of nanoparticles in the superlattice, φ, which minimized the level of distortion of the dehydrated superlattice, was found for each bcc and fcc structure. By acquiring clear SAXS diffraction patterns showing crystal symmetries for dehydrated DNA-NP superlattices, their lattice distortion was evaluated using our analysis technique, which is based on Hosemann's paracrystalline theory and involves SAXS and scanning electron microscopy data. Geometrical calculations substantiated the ease of movement of a nanoparticle under the influence of repulsions from adjacent particles that mainly affect the dehydration stability. These results suggest that it is possible to design the crystal structure of solid nanoparticle superlattices via DNA-guided nanoparticle assembly under a near-equilibrium state in solution as the first step, followed by dehydration under nonequilibrium conditions as the second step.

DOI： 10.1021/acs.cgd.1c00398

Open Access

Web of Science

Scopus

Y Local Atomic Structures for Tunable Ordered Arrangements of Crystallographic Shear Planes in Titanium-Chromium Oxide Natural Superlattices 査読有り

Harada Shunta, Sugimoto Shunya, Kosaka Naoki, Tagawa Miho, Ujihara Toru

JOURNAL OF PHYSICAL CHEMISTRY C 125 巻 ( 28 ) 頁： 15730 - 15736 2021年7月

担当区分：筆頭著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physical Chemistry C

The atomic structure of titanium-chromium oxide natural superlattices with different compositions having an ordered arrangement of crystallographic shear (CS) planes was investigated by high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) and electron diffraction, using polycrystalline ceramics prepared by arc-melting and heat treatment. Analysis of the electron diffraction patterns revealed that not only the interspacing but also the direction of planar faults changed depending on the chromium concentration. HAADF-STEM observations showed that the atomic arrangements of CS planes deviating from (121)rutile are random arrangements of (121)rutile CS planes and (011)rutile antiphase boundaries. Using a random walk model and by calculating the specularity parameter, we found that the CS planes in titanium-chromium oxides behave as coherent interfaces for phonons based on the estimation of interface roughness.

DOI： 10.1021/acs.jpcc.1c04516

Web of Science

Scopus

Ordered Arrangement of Planar Faults with Picoscale Perfection in Titanium Oxide Natural Superlattices 査読有り

The Journal of Physical Chemistry C 125 巻 ( 20 ) 頁： 11175 - 11181 2021年5月

Design of automatic detection algorithm for dislocation contrasts in birefringence images of SiC wafers 査読有り

Kawata Akira, Murayama Kenta, Sumitani Shogo, Harada Shunta

JAPANESE JOURNAL OF APPLIED PHYSICS 60 巻 ( SB ) 2021年5月

Synchrotron X-ray topographic image contrast variation of screw-type basal plane dislocations located at different depths below the crystal surface in 4H-SiC 査読有り国際共著

Fujie Fumihiro, Peng Hongyu, Ailihumaer Tuerxun, Raghothamachar Balaji, Dudley Michael, Harada Shunta, Tagawa Miho, Ujihara Toru

ACTA MATERIALIA 208 巻 2021年4月

Geometrical design of a crystal growth system guided by a machine learning algorithm 査読有り

Wancheng Yu, Can Zhu, Wei Huang, Dang Yifan, Kentaro Kutsukake, Shunta Harada, Miho Tagawa, Toru Ujihara

CrystEngComm 23 巻 ( 14 ) 頁： 2695 - 2702 2021年4月

Adaptive process control for crystal growth using machine learning for high-speed prediction: application to SiC solution growth

Dang Yifan, Zhu Can, Ikumi Motoki, Takaishi Masaki, Yu Wancheng, Huang Wei, Liu Xinbo, Kutsukake Kentaro, Harada Shunta, Tagawa Miho, Ujihara Toru

CrystEngComm 23 巻 ( 9 ) 頁： 1982 - 1990 2021年3月

Analysis of dislocation line tilt in GaN single crystal by Raman spectroscopy

Kokubo Nobuhiko, Tsunooka Yosuke, Inotsume Sho, Fujie Fumihiro, Onda Shoichi, Yamada Hisashi, Shimizu Mitsuaki, Harada Shunta, Tagawa Miho, Ujihara Toru

JAPANESE JOURNAL OF APPLIED PHYSICS 60 巻 ( SA ) 2021年1月

大口径SiCバルク結晶成長における主要技術とプロセス・インフォマティクスの活用

宇治原徹, 朱燦, 角岡洋介, 古庄智明, 鈴木皓己, 沓掛健太朗, 高石将輝, 郁万成, 黨一帆, 磯野優, 竹内一郎, 田川美穂, 原田俊太

日本結晶成長学会誌 48 巻 ( 3 ) 頁： n/a 2021年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：日本結晶成長学会

<p> We have been developing a SiC crystal growth technique using the solution method. As a result, we have achieved the growth of ultra-high quality crystals with extremely low dislocation density. The key to this is the reduction of dislocation density by utilizing the macro-step dislocation conversion phenomenon and the suppression of surface morphology roughness by controlling the flow in the solution. In order to put these technologies to practical use, we have developed a new machine learning technique for optimizing crystal growth conditions for large-diameter crystals. In this method, a model is constructed in the computer that reproduces the actual experiment quickly and accurately, and then hundreds of thousands or millions of trials are performed using the model to derive the experimental conditions with high efficiency. This means that optimization by surrogate models, which is one of the methods of process informatics, has been realized in crystal growth. By using these techniques, we were able to achieve 6-inch crystal growth in a very short time.</p>

DOI： 10.19009/jjacg.48-3-04

CiNii Research

Numerical investigation and optimization of time evolution in the solution during solution growth for SiC crystal

Dang Yifan, Zhu Can, Yu Wancheng, Huang Wei, Ikumi Motoki, Harada Shunta, Tagawa Miho, Ujihara Toru

JSAP Annual Meetings Extended Abstracts 2020.2 巻 ( 0 ) 頁： 2128 - 2128 2020年8月

Temperature dependence of double Shockley stacking fault behavior in nitrogen-doped 4H-SiC studied by in-situ synchrotron X-ray topography

Fujie Fumihiro, Harada Shunta, Hanada Kenji, Suo Hiromasa, Koizumi Haruhiko, Kato Tomohisa, Tagawa Miho, Ujihara Toru

ACTA MATERIALIA 194 巻頁： 387 - 393 2020年8月

Behavior of Threading Dislocations from GaN Substrate to Epitaxial Layer

Inotsume Sho, Kokubo Nobuhiko, Yamada Hisashi, Onda Shoichi, Kojima Jun, Ohara Junji, Harada Shunta, Tagawa Miho, Ujihara Toru

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 257 巻 ( 4 ) 2020年4月

Demonstration of Observation of Dislocations in GaN by Novel Birefringence Method

Tanaka Atsushi, Inotsume Syo, Harada Shunta, Hanada Kenji, Honda Yoshio, Ujihara Toru, Amano Hiroshi

PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS 257 巻 ( 4 ) 2020年4月

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