Kenji Yamaguchi
Japan Atomic Energy Agency
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Featured researches published by Kenji Yamaguchi.
Japanese Journal of Applied Physics | 2006
Masato Sasase; Kenichiro Shimura; Hiroyuki Yamamoto; Kenji Yamaguchi; Shin-ichi Shamoto; Kiichi Hojou
The effect of a silicon substrate surface pretreatment on epitaxial iron silicide film formation on a Si(100) substrate with ion beam sputter deposition (IBSD) was investigated. In this study, two surface pretreatment methods namely, thermal etching (TE) and sputter etching (SE) with subsequent thermal annealing, were employed. The interface structure between a β-FeSi2 film and a Si substrate was analyzed by cross-sectional observation using a transmission electron microscope (XTEM). High-resolution XTEM images showed that the lattice of the Si substrate is an almost perfect crystal immediately after the TE treatment. However, the TE treatment results in an undulated interface, and the deposited silicide contained coalesced β-FeSi2 islands. On the other hand, the dislocations and stacking faults produced by radiation damage were observed near the Si substrate surface for the SE treatment. Even though this treatment produced defects, the interface of the SE-treated epitaxial β-FeSi2(100) film had a smooth interface after the deposition at 973 K. It can be concluded that a moderate disorder of the silicon substrate surface treated by SE may well enhance the mixing of Fe and Si atoms for the epitaxial growth of β-FeSi2.
Materials Science and Engineering: C | 2014
Tomitsugu Taguchi; Toshiki Miyazaki; Satoshi Iikubo; Kenji Yamaguchi
SiC nanotubes can become candidate reinforcement materials for dental and orthopedic implants due to their light weight and excellent mechanical properties. However, the development of bioactive SiC materials has not been reported. In this study, hydroxyapatites were found on SiC nanotubes treated with NaOH and subsequently HCl solution after soaking in simulated body fluid. On the other hand, hydroxyapatites did not deposit on as-received SiC nanotubes, the SiC nanotubes with NH4OH solution treatment and SiC bulk materials with NaOH and subsequently HCl solution treatment. Therefore, we succeeded in the development of bioactive SiC nanotubes by downsizing SiC materials to nanometer size and treating with NaOH and subsequently HCl solutions for the first time.
Journal of Physics: Conference Series | 2008
M Sasase; Kenji Yamaguchi; Hiroyuki Yamamoto; Shin-ichi Shamoto; Kiichi Hojou
β-FeSi2 is one of the possible candidates for a compound semiconductor. Epitaxial β-FeSi2 films grown on a Si substrate are technologically important for microelectronic and silicon-based optoelectronic applications. In earlier studies, we clarified that the treatment of the Si substrate surface greatly influences the crystal structure of the film. Among several surface treatment procedures, it has been reported that the sputter etching (SE) of the substrate with subsequent thermal annealing is fairly effective in obtaining a film that has a favorable epitaxial orientation relationship of β-FeSi2(100)//Si(100) with atomically smooth interface by choosing better conditions. Even though the obtained films have good quality, anomalous patterns were sometime observed in the dark field image of the obtained film by cross-sectional TEM observation. They formed a horizontal line along the β-FeSi2/Si interface. Higher magnification image shows that these spots are aggregated defects. The lines tend to appear in the samples, which are irradiated in higher energy. However, they are also occasionally observed in 1 keV Ne+ irradiated sample. It can be related to the diffusion process of the silicon atoms and the defects formed in the silicon through Ne+ irradiation. Formation behavior of these aligned defects will be discussed in the present study.
Proceedings of the 12th Asia Pacific Physics Conference (APPC12) | 2014
Shin-ichi Shamoto; Katsuaki Kodama; Tadashi Imaki; Takeshi Nakatani; Hidetoshi Oshita; Naokatsu Kaneko; Kenji Masuko; Kensaku Sakamoto; Kenji Yamaguchi; Kentaro Suzuya; Toshiya Otomo
Materials Science Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan Information Technology Systems Management and Operating Office, Center for Computational Science & e-Systems, Tokai, Ibaraki, 319-1195, Japan J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan
Applied Surface Science | 2010
Fumitaka Esaka; Hiroyuki Yamamoto; Nobuyuki Matsubayashi; Yoichi Yamada; M. Sasase; Kenji Yamaguchi; Shin-ichi Shamoto; Masaaki Magara; T. Kimura
Thin Solid Films | 2006
Kenji Yamaguchi; Kenichiro Shimura; Haruhiko Udono; Masato Sasase; Hiroyuki Yamamoto; Shin-ichi Shamoto; Kiichi Hojou
Applied Surface Science | 2011
Fumitaka Esaka; Hiroyuki Yamamoto; Haruhiko Udono; Nobuyuki Matsubayashi; Kenji Yamaguchi; Shin-ichi Shamoto; Masaaki Magara; T. Kimura
Thin Solid Films | 2007
M. Muroga; Hirokazu Suzuki; Haruhiko Udono; Isao Kikuma; A. Zhuravlev; Kenji Yamaguchi; Hiroyuki Yamamoto; Takayuki Terai
Journal of Electron Microscopy | 2004
Shinichi Igarashi; Masaharu Haraguchi; Jun Aihara; Takeru Saito; Kenji Yamaguchi; Hiroyuki Yamamoto; Kiichi Hojou
Journal of Crystal Growth | 2013
Hidehito Asaoka; T. Yamazaki; Yuta Yokoyama; Kenji Yamaguchi