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373 results on '"Harada, Shinsuke"'

1. Dipole Scattering at the Interface: The Origin of Low Mobility observed in SiC MOSFETs

Author

Hatakeyama, Tetsuo, Hirai, Hirohisa, Simetani, Mitsuru, Okamoto, Dai, Okamoto, Mitsuo, and Harada, Shinsuke

Subjects
Physics - Applied Physics
Abstract

In this work, the origin of the low free electron mobility in SiC MOSFETs is investigated using the scattering theory of two-dimensional electron gases. We first establish that neither phonon scattering nor Coulomb scattering can be the cause of the low observed mobility in SiC MOSFETs; we establish this fact by comparing the theoretically calculated mobility considering these effects with experimental observations. By considering the threshold voltages and the effective field dependence of the mobility in SiC MOSFETs, it is concluded that the scattering centers of the dominant mechanism are electrically neutral and exhibit a short-range scattering potential. By considering charge distribution around a neutral defect at the interface, it is established that an electric dipole induced by the defect can act as a short-range scattering potential. We then calculate the mobility in SiC MOSFETs assuming that there exist a high density of dipoles at the interface. The calculated dipole-scattering-limited mobility shows a similar dependence on the effective field dependence to that observed in experimental results. Thus, we conclude that scattering induced by a high density of electric dipoles at the interface is dominant cause of the low mobility in SiC MOSFETs., Comment: 16pages, 3 figures

Published
2022
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6. Characterization of Traps at Nitrided SiO$_2$/SiC Interfaces near the Conduction Band Edge by using Hall Effect Measurements

Author

Hatakeyama, Tetsuo, Kiuchi, Yuji, Sometani, Mitsuru, Harada, Shinsuke, Okamoto, Dai, Yano, Hiroshi, Yonezawa, Yoshiyuki, and Okumura, Hajime

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

The effects of nitridation on the density of traps at SiO$_2$/SiC interfaces near the conduction band edge were qualitatively examined by a simple, newly developed characterization method that utilizes Hall effect measurements and split capacitance-voltage measurements. The results showed a significant reduction in the density of interface traps near the conduction band edge by nitridation, as well as the high density of interface traps that was not eliminated by nitridation.

Published
2017
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22. Significant Improvement of Switching Characteristics in a 1.2‐kV SiC SWITCH‐MOS by the Application of Kelvin Source Connection.

Author

Matsui, Kevin, Tawara, Takeshi, Harada, Shinsuke, Tanaka, So, Sato, Hiroshi, Yano, Hiroshi, and Iwamuro, Noriyuki

Subjects
SCHOTTKY barrier diodes, SCHOTTKY barrier, ELECTRICAL engineers
Abstract

Here we show, for the first time, a significant improvement of switching characteristics in a 1.2‐kV SiC Schottky barrier diode‐wall integrated trench MOSFET (SWITCH‐MOS) by the application of a Kelvin source (KS) connection. Turn‐on loss (Eon) was greatly reduced, with superior Eon‐dVDS/dt trade‐off characteristics at a moderate dVDS/dt value of about 10 kV/μs, because the SWITCH‐MOS with KS achieves a more suppressed peak reverse recovery current in embedded Schottky barrier diodes even at a higher dID/dt during the turn‐on operation than a state‐of‐the‐art SiC trench MOSFET with KS. This feature is a peculiarity of the SWITCH‐MOS when the KS connection is applied. Notably, measured and calculated results confirmed that the SWITCH‐MOS with KS had less dissipated turn‐off loss, especially in a second half of turn‐off regions (Region 2), than the SWITCH‐MOS w/o KS. However, owing to a higher negative turn‐off dID/dt, the MOSFET with KS has a larger drain surge voltage. With an optimum gate resistance, the SWITCH‐MOS with KS has 8% less total switching loss than a SWITCH‐MOS without KS, and 29% less than a state‐of‐the‐art SiC trench MOSFET with KS, while keeping a moderately low dVDS/dt of 10 kV/μs and suppressing a drain peak voltage of <720 V. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Published
2023
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25. Reduction of Forward Bias Degradation in 4H-SiC PiN Diodes Fabricated on 4H-SiC Bonded Substrates

Author

Hatta, Naoki, Ishikawa, Seiji, Ozono, Kunihide, Masumoto, Keiko, Yagi, Kuniaki, Kobayashi, Motoki, Kurihara, Shunsuke, Harada, Shinsuke, and Kojima, Kazutoshi

Abstract

The advantage in reducing forward bias degradation of bipolar 4H-SiC devices using a 4H-SiC bonded substrate is demonstrated. To evaluate the differences in forward bias degradation between a 4H-SiC bonded substrate and a commercially available 4H-SiC bulk substrate, a forward current stress test and subsequent photoluminescence (PL) imaging of PiN diodes fabricated on both the substrates were performed. Unlike the bulk substrate, the bonded substrate maintained a low ΔVf and the variation among the measured diodes was extremely small even after applying the highest current density of 1500 A/cm2. The investigated number of bar-shaped SSFs within the electrically stressed diodes with more than 1000 A/cm2 revealed the possibility that the BPDs existing at deep positions below the epilayer/substrate interface were drastically reduced in the 4H-SiC bonded substrate.

Published
2023
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35. Electrical detection of TV2a-type silicon vacancy spin defect in 4H-SiC MOSFETs

Author

Yuta, Abe, Akifumi, Chaen, Sometani, Mitsuru, Harada, Shinsuke, Yuichi, Yamazaki, Takeshi, Ohshima, and Umeda, Takehide

Abstract

Color centers in silicon carbide (4H-SiC) are potentially usable as spin defects for quantum sensing and quantum information technology. In particular, neutral divacancies (the P6/P7centers, VSiVC 0) and a certain type of silicon vacancies (the TV2a center, VSi - at the k site) are promising for addressing and manipulating single spins. Although the TV2a spin is readable at room temperature, the readout techniques have been limited to luminescence-based ones (e.g., optically detected magnetic resonance). In this study, we demonstrated electrical detection of TV2a-type silicon vacancies at room temperature by using electrically detected magnetic resonance on 4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs). TV2a spin defects were embedded in the channel region of well-defined 4H-SiC MOSFETs via controlled proton irradiation. The number of detected TV2a spins was estimated to be 10^5. We also found that the charge state of the TV2a spin defect can be controlled by varying the gate voltage applied to the MOSFET.

Published
2022

46. Electrical detection of TV2a-type silicon vacancy spin defect in 4H-SiC MOSFETs.

Author

Abe, Yuta, Chaen, Akihumi, Sometani, Mitsuru, Harada, Shinsuke, Yamazaki, Yuichi, Ohshima, Takeshi, and Umeda, Takahide

Subjects
FIELD-effect transistors, METAL oxide semiconductor field, METAL oxide semiconductor field-effect transistors, MAGNETIC resonance, SILICON, SILICON carbide
Abstract

Color centers in silicon carbide (4H-SiC) are potentially usable as spin defects for quantum sensing and quantum information technology. In particular, neutral divacancies (the P6/P7centers, VSiVC0) and a certain type of silicon vacancies (the TV2a center, VSi- at the k site) are promising for addressing and manipulating single spins. Although the TV2a spin is readable at room temperature, the readout techniques have been limited to luminescence-based ones (e.g., optically detected magnetic resonance). In this study, we demonstrated electrical detection of TV2a-type silicon vacancies at room temperature by using electrically detected magnetic resonance on 4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs). TV2a spin defects were embedded in the channel region of well-defined 4H-SiC MOSFETs via controlled proton irradiation. The number of detected TV2a spins was estimated to be ∼105. We also found that the charge state of the TV2a spin defect can be controlled by varying the gate voltage applied to the MOSFET. [ABSTRACT FROM AUTHOR]

Published
2022
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