Papers by Author: Tsunenobu Kimoto

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Authors: Masato Noborio, Jun Suda, Tsunenobu Kimoto
Abstract: SiC lateral double RESURF MOSFETs have been fabricated on the 4H-SiC (000-1)C face. By utilizing the C face, the channel resistance can be reduced because the C-face MOSFETs show higher channel mobility than the Si-face MOSFETs. In addition, by employing the double RESURF structure, the drift resistance is decreased and the breakdown voltage is increased with increasing the RESURF doses. The fabricated RESURF MOSFETs on the 4H-SiC (000-1)C face have demonstrated a low on-resistance of 40 mΩcm2 at an oxide field of 3 MV/cm and a breakdown voltage of 1580 V at zero gate bias. The figure-of-merit of the MOSFET is 62 MW/cm2, which is more than 10 times better than the conventional “Si limit” and the highest value among any lateral MOSFETs to date.
Authors: Qamar-ul Wahab, Hajime Kosugi, Hiroshi Yano, Christer Hallin, Tsunenobu Kimoto, Hiroyuki Matsunami
Authors: Tsunenobu Kimoto, Toshihiro Yamamoto, Zhi Yong Chen, Hiroshi Yano, Hiroyuki Matsunami
Authors: Hiroaki Saitoh, Tsunenobu Kimoto
Abstract: Chemical vapor deposition of 4H-SiC on (0001) substrates with various off-angles from 1o to 45o has been investigated. On large-off-angled (15o-45o) substrates, very smooth surface morphology is obtained in the wide range of C/Si ratio. The micropipe dissociation during epitaxial growth is observed on 4o-45o off-angled substrates with a low C/Si ratio. The incorporation of nitrogen was dramatically suppressed by increasing C/Si ratio irrespective of substrate’s off-angle.
Authors: T. Hirao, Hiroshi Yano, Tsunenobu Kimoto, Hiroyuki Matsunami, Hiromu Shiomi
Authors: J. Kaido, Tsunenobu Kimoto, Jun Suda, Hiroyuki Matsunami
Authors: Kazuhiro Fujikawa, Shinsuke Harada, Atsuo Ito, Tsunenobu Kimoto, Hiroyuki Matsunami
Authors: Hironori Yoshioka, Takashi Nakamura, Junji Senzaki, Atsushi Shimozato, Yasunori Tanaka, Hajime Okumura, Tsunenobu Kimoto
Abstract: We focused on the inability of the common high-low method to detect very fast interface states, and developed methods to evaluate such states (CψS method). We have investigated correlation between the interface state density (DIT) evaluated by the CψS method and MOSFET performance, and found that the DIT(CψS) was well reflected in MOSFET performance. Very fast interface states which are generated by nitridation restricted the improvement of subthreshold slope and field-effect mobility.
Authors: Hiroshi Yano, Toshio Hirao, Tsunenobu Kimoto, Hiroyuki Matsunami, Katsunori Asano, Yoshitaka Sugawara
Authors: Walter M. Klahold, Robert P. Devaty, Wolfgang J. Choyke, Koutarou Kawahara, Tsunenobu Kimoto, Takeshi Ohshima
Abstract: Ultra-pure n-type (8×1013 cm-3), 99 μm thick epitaxial films of 4H SiC were electron irradiated at 170 keV with a fluence of 5×1016 cm-2 or at 1 MeV with a fluence of 1×1015 cm-2 in various geometries. Low temperature photoluminescence (LTPL) spectra and microwave photoconductance (μPCD) lifetime measurements were obtained on all samples prior to annealing and after annealing in Argon in free standing mode or on a POCO carbon platform, every 50°C from 1100°C to 1500°C. No improvement in carrier lifetime was obtained. Spurious lines attributable to the use of a Genesis CX 3550Å laser are also reported.
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