Papers by Author: Makoto Kitabatake

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Authors: Toshiya Yokogawa, Kunimasa Takahashi, Osamu Kusumoto, Masao Uchida, Kenya Yamashita, Makoto Kitabatake
Authors: Tamotsu Yamashita, Kenji Momose, Daisuke Muto, Yoshiki Shimodaira, Kuniaki Yamatake, Yoshihiko Miyasaka, Takayuki Sato, Hirofumi Matsuhata, Makoto Kitabatake
Abstract: We report our investigation results on triangular-defects formed on 4deg. off 4H-SiC epi- taxial wafers. Triangular-defects that had neither down-falls nor basal-plane dislocations previously reported as origins of triangular-defects at the tips of triangle were investigated by TEM. Our TEM results revealed that foreign materials contamination that were different from well-known down- -falls in size and in composition caused one of the defect formations and abnormal domain forma- tions were implied to occur and thought to relate to defect formations. We also report that several types of microstructure existed in the isosceles of defect during dislocation analyses around triangular-defects by X-ray topography.
Authors: Kunimasa Takahashi, Toshiya Yokogawa, Masao Uchida, Osamu Kusumoto, Kenya Yamashita, Ryouko Miyanaga, Makoto Kitabatake
Authors: Kunimasa Takahashi, Masao Uchida, Osamu Kusumoto, Kenya Yamashita, Ryouko Miyanaga, Makoto Kitabatake
Authors: M. Uchida, M. Deguchi, Kazuhiko Takahashi, Makoto Kitabatake, M. Kitagawa
Authors: Kunimasa Takahashi, Masao Uchida, Makoto Kitabatake
Authors: Noboru Ohtani, Masakazu Katsuno, T. Fujimoto, S. Sato, Hiroshi Tsuge, Wataru Ohashi, Hirofumi Matsuhata, Makoto Kitabatake
Abstract: Defect formation during the early stages of physical vapor transport (PVT) growth of 4H-SiC was investigated using high resolution x-ray diffraction (HRXRD). Characteristic lattice bending behaviors were revealed in the nearby seed crystal regions of grown crystals. The lattice bending was localized in close proximity to the seed/grown crystal interface, and the (0001) basal planes bended convexly toward the growth direction, indicative of the insertion of extra-half planes pointing toward the growth direction during the initial stages of crystal growth. This paper discusses the possible mechanisms of the observed lattice bending and sheds light on the defect formation processes during PVT-growth of 4H-SiC single crystals.
Authors: Yoshio Ota, Yasushi Ikeda, Makoto Kitabatake
Authors: Makoto Kitabatake, M. Tagome, S. Kazama, K. Yamashita, K. Hashimoto, Kunimasa Takahashi, O. Kusumoto, Kazuya Utsunomiya, Masashi Hayashi, M. Uchida, R. Ikegami, C. Kudo, S. Hashimoto
Abstract: Large (3.6 x 3.6 mm2) chips of the SiC DACFET were fabricated and mounted in TO220 packages. The drain-source avalanche breakdown voltage without any gate bias (Vgs=0V) is measured to be >1400V. The SiC DACFET keeps the normally-off characteristics even at 150°C. Ron and specific Ron of the SiC DACFET is measured to be 62mΩ and 6.7 mΩcm2 at RT while those at 150°C change to 107 mΩ and 11.6 mΩcm2. The 400V / 3 kW DC-DC switched-mode power-conversion circuit with 100kHz switching was fabricated using the SiC DACFET and the SiC SBD. The turn-off switching loss reduces dramatically using the SiC-DACFET down to 77μJ/pulse which is less than 1/10 of that using the Si-IGBT.
Authors: Kenya Yamashita, Kyoko Egashira, Koichi Hashimoto, Kunimasa Takahashi, Osamu Kusumoto, Kazuya Utsunomiya, Masashi Hayashi, Masao Uchida, Chiaki Kudo, Makoto Kitabatake, Shin Hashimoto
Abstract: In order for SiC-MOSFET to be practical in various power electronics applications, low specific on-resistance Ron,sp, high breakdown voltage and “normally-off” characteristics have to be fulfilled even at high temperature. We fabricated a SiC-MOSFET employing a submicron gate with channel length Lg of 0.5μm by a self-aligned implantation and aδ-doped epitaxial channel layer to successfully demonstrate the following features. The normally-off characteristics was confirmed from room temperature to 200°C where the therethold voltages Vth were 2.9V at room temperature and 1.6V at 200°C, respectively. The Ron,sp were 4.6mΩcm2 at room temperature and 9.2mΩcm2 at 200°C, respectively, while the breakdown voltage was greater than 1400V .
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