Prof. Tetsu Kachi Profile

Prof. Tetsu Kachi

Designated Professor at Nagoya Univ

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Publications (8)

Proceedings Article | 21 March 2023 Presentation

Recent development of GaN Power switching devices with Ion Implantation technology

Tetsu Kachi, Hideki Sakurai, Testo Narita, Maciej Matys, Jun Suda

Proceedings Volume PC12421, (2023) https://doi.org/10.1117/12.2649083

KEYWORDS: Ion implantation, Gallium nitride, Doping, Switching, Magnesium, Diodes, Diffusion, Field effect transistors, Annealing

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Proceedings Article | 21 March 2023 Presentation

Impacts of vacancy clusters on the recombination dynamics in Mg-implanted GaN on GaN structures

Shigefusa Chichibu, Kohei Shima, Hiroko Iguchi, Tetsuo Narita, Keita Kataoka, Hideki Sakurai, Michal Bockowski, Jun Suda, Tetsu Kachi, Shinya Takashima, Ryo Tanaka, Katsunori Ueno, Masaharu Edo, Shoji Ishibashi, Akira Uedono

Proceedings Volume PC12421, (2023) https://doi.org/10.1117/12.2646375

KEYWORDS: Gallium nitride, Luminescence, Ultraviolet radiation, Magnesium, Gallium, Doping, Annealing

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Proceedings Article | 15 March 2023 Presentation + Paper

Annealing properties of vacancy-type defects in ion implanted GaN during ultra-high-pressure annealing studied by using a monoenergetic positron beam

Akira Uedono, Hideki Sakurai, Jun Uzuhashi, Tetsuo Narita, Kacper Sierakowski, Shoji Ishibashi, Shigefusa Chichibu, Michal Bockowski, Jun Suda, Tadakatsu Ohokubo, Nobuyuki Ikarashi, Kazuhiro Hono, Tetsu Kachi

Proceedings Volume 12421, 124210C (2023) https://doi.org/10.1117/12.2646233

KEYWORDS: Annealing, Gallium nitride, Magnesium, Gallium, Ions, Ion implantation, Silicon, Doppler effect, Solids, Chemical species

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Proceedings Article | 5 March 2021 Presentation

Behaviors of vacancy-type defects in Mg-implanted GaN during ultra-high-pressure annealing studied by using a monoenergetic positron beam

A. Uedono, H. Sakurai, T. Narita, K. Sierakowski, M. Bockowski, J. Suda, S. Ishibashi, S. Chichibu, T. Kachi

Proceedings Volume 11686, 116861P (2021) https://doi.org/10.1117/12.2575972

KEYWORDS: Gallium nitride, Annealing, Magnesium, Ion implantation, Doping, Spectroscopy, Ions, Nitrogen, Temperature metrology, Aluminum nitride

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Proceedings Article | 13 March 2019 Presentation

Vertical GaN power devices: current status and future prospects (Conference Presentation)

Tetsu Kachi

Proceedings Volume 10918, 1091815 (2019) https://doi.org/10.1117/12.2509733

KEYWORDS: Gallium nitride, Molybdenum, Field effect transistors, Silicon carbide, Heterojunctions, Resistance

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Proceedings Article | 13 March 2019 Presentation

Recent progress of Mg-ion implantation and thermal activation process for p-doping in GaN (Conference Presentation)

Hideki Sakurai, Masato Omori, Shinji Yamada, Yukihiro Furukawa, Hideo Suzuki, Tetsuo Narita, Keita Kataoka, Michal Bockowski, Jun Suda, Tetsu Kachi

Proceedings Volume 10918, 109180V (2019) https://doi.org/10.1117/12.2508417

KEYWORDS: Gallium nitride, Annealing, Doping, Crystals, Lamps, Ion implantation, Nitrogen, Luminescence, Atomic force microscopy, Surface roughness

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Ion implantation (I/I) and annealing techniques to enable high carrier doping into selected regions are one of important research fields for realization of GaN power devices. However, particularly difficult research challenges are present in Mg-I/I into GaN as p-type doping technique. First problem is related to nitrogen vacancies (VN), crystal defects introduced by Mg-I/I . [1] Second issue is connected to degeneration of GaN surface by pyrolysis reaction during high-temperature annealing process. We examined Mg/N co-implantation into GaN as p-doping in order to compensate of VN defects. Research on ultra-high pressure thermal activation process to maintain equilibrium conditions at high temperature was conducted to avoid degradation of GaN surface. We prepared Mg/N co-implanted GaN-on-GaN samples with 300-nm-deep Mg-box-profile of 1E19 cm-3 and with N-box-profile of various concentrations in the range 0 ~ 1E20 cm-3. The samples were annealed without a protection cap layer at temperature between 1300 °C and 1480 °C under 1 GPa in N2 atmosphere. Samples capped with sputter-AlN were treated by conventional lamp annealing at 1300 °C for a comparison purpose. We obtained the dominant Green Luminescence (GL) emission at 2.3 eV and the recessive Donor Acceptor Pair (DAP) emission at 3.2 eV from a low-temperature cathodoluminescence (LT-CL) spectra in Mg-I/I samples without N co-implantation. This is in good agreement with results published before.[1][2] In addition to this, we found that the Mg/N co-implantation, for optimized N-ion dose, suppresses the GL intensity while maintaining the DAP intensity. Furthermore, in the ultra-high pressure thermal activation process, the DAP intensity markedly increases with anneal temperature and GL intensity suppression is also visible. These results strongly suggest that the origin of GL is related to VN, and the VN defect compensation occurs by N co-implantation. We also compare the AFM images of GaN surface roughness. The ultra-high pressure annealed surfaces were as smooth (RMS = 0.2~0.3 nm) as the as-implanted samples (0.3 nm), whereas surface treated with conventional lamp was rough (1.9 nm). We can, therefore, conclude that Mg/N co-implantation and ultra-high pressure thermal activation process allows activation of the Mg acceptor and recovery of p-GaN crystal quality. Such treatment results in VN defect compensation and a smooth surface of the annealed sample. This work was supported by MEXT “Program for research and development of next-generation semiconductor to realize energy-saving society.” [1] A. Uedono et al., Phys. Status Solidi B 252, No. 12 (2015) [2] K. Kojima et al., Appl. Phys. Express 10, 061002 (2017).

Proceedings Article | 19 April 2017 Presentation

Current status and future on GaN power devices for automobile applications (Conference Presentation)

Tetsu Kachi

Proceedings Volume 10104, 1010416 (2017) https://doi.org/10.1117/12.2254513

KEYWORDS: Interfaces, Current controlled current source, Gallium nitride, Reliability, Silica, Field effect transistors

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Proceedings Article | 27 March 2013 Paper

GaN power devices for automotive applications

T. Uesugi, Tetsu Kachi

Proceedings Volume 8625, 86250V (2013) https://doi.org/10.1117/12.2002248

KEYWORDS: Gallium nitride, Field effect transistors, Silicon, Silicon carbide, Dielectrics, Hybrid vehicles, Silica, Reliability, Switching, Atomic layer deposition

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