Yasuyuki Ogata
Japan Aerospace Exploration Agency
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Featured researches published by Yasuyuki Ogata.
Annals of the New York Academy of Sciences | 2006
Kyoichi Kinoshita; Yasuyuki Ogata; Satoshi Adachi; Shinichi Yoda; Tetsuya Tsuru; Hiroaki Miyata; Yuji Muramatsu
Abstract: The influence of convection in a melt on the crystallinity of the TLZ‐grown In0.3Ga0.7As crystals has been investigated by growing crystals with various shapes and dimensions on the ground. No single crystals have been grown when the crystal diameter was 10 mm, but we were successful in growing single crystals by reducing crystal diameter to 2 mm. These results suggested the importance of suppressing convection in the melt during alloy crystal growth because constitutional supercooling tends to occur at the freezing interface or ahead of the interface by the segregation effect. Large area is required for substrate use in various applications. This requirement can be fulfilled by the crystal growth in microgravity because density difference–induced convection is suppressed in microgravity. Another means for suppressing convection without deteriorating area is plate‐shape crystal growth with reduced thickness. The latter can be applied on the ground and we succeeded in growing single crystals of plate‐shaped In0.3Ga0.7As by the traveling liquidus zone (TLZ) method. Dimensions of obtained single crystals were 10 mm in width and 2 mm in thickness and lengths ranged from 20 to 40 mm. Compositional uniformity was good and 0.3 ± 0.02 in InAs mole fraction was achieved.
Microgravity Science and Technology | 2005
Kyoichi Kinoshita; Yasuyuki Ogata; Satoshi Adachi; Naokiyo Koshikawa; Shinichi Yoda
The influence of convection in a melt on the compositional homogeneity of the TLZ-grown In0.3Ga0.7As crystals has been investigated by growing crystals with various dimensions on the ground. Excellent compositional homogeneity such as 0.3 plus or minus 0.01 in InAs mole fraction for a distance of 25 mm was obtained when the melt diameter was limited to 2 mm and convective flow in the melt was suppressed. On the other hand, when the crystal diameter was increased to 10 mm, both axial and radial compositional homogeneity was deteriorated due to convection in the melt. Comparing with the numerical simulation, convective flow velocity less than 1.4 mm/h may be sufficient for growing homogeneous crystals and it is not so difficult to suppress convective flow velocity below 1.4 mm/h for 10 mm diameter crystals in microgravity. Therefore, larger homogeneous In0.3Ga0.7As crystals are expected to be grown by the TLZ method on board the International Space Station.
Journal of Crystal Growth | 2005
Satoshi Adachi; Yasuyuki Ogata; Naokiyo Koshikawa; Satoshi Matsumoto; Kyoichi Kinoshita; Izumi Yoshizaki; Tetsuya Tsuru; Hiroaki Miyata; Masahiro Takayanagi; Shinichi Yoda
Journal of Crystal Growth | 2007
Hiroaki Miyata; Satoshi Adachi; Yasuyuki Ogata; Tetsuya Tsuru; Yuji Muramatsu; Kyoichi Kinoshita; Osamu Odawara; Shinichi Yoda
Journal of Crystal Growth | 2004
Satoshi Adachi; Yasuyuki Ogata; N. Koshikawa; Satoshi Matsumoto; Kyoichi Kinoshita; Izumi Yoshizaki; Masahiro Takayanagi; Shinichi Yoda; Akio Kadowaki; Tetsuya Tsuru; Hiroaki Miyata; Yuji Muramatsu
Journal of Crystal Growth | 2004
Satoshi Adachi; Yasuyuki Ogata; Naokiyo Koshikawa; Satoshi Matsumoto; Kyoichi Kinoshita; Masahiro Takayanagi; Shinichi Yoda
Journal of Crystal Growth | 2006
Hiroaki Miyata; Satoshi Adachi; Yasuyuki Ogata; Tetsuya Tsuru; Yuji Muramatsu; Kyoichi Kinoshita; Osamu Odawara; Shinichi Yoda
Journal of Crystal Growth | 2004
Satoshi Adachi; Yasuyuki Ogata; Naokiyo Koshikawa; Satoshi Matsumoto; Kyoichi Kinoshita; Izumi Yoshizaki; Masahiro Takayanagi; Shinichi Yoda
Physica Status Solidi (a) | 2006
Hiroaki Miyata; Satoshi Adachi; Yasuyuki Ogata; Tetsuya Tsuru; Yuji Muramatsu; Kyoichi Kinoshita; Osamu Odawara; Shinichi Yoda
Archive | 2006
Kyoichi Kinoshita; Yasuyuki Ogata; Satoshi Adachi; Masakazu Arai; Takao Watanabe; Yashuhiro Kondo; Shinichi Yoda; 恭一 木下; 康行 緒方; 聡 足立; 昌和 荒井; 孝夫 渡辺; 康洋 近藤; 眞一 依田