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Yogo, Akifumi*; Lan, Z.*; Arikawa, Yasunobu*; Abe, Yuki*; Mirfayzi, S. R.*; Wei, T.*; Mori, Takato*; Golovin, D.*; Hayakawa, Takehito*; Iwata, Natsumi*; et al.
Physical Review X, 13(1), p.011011_1 - 011011_12, 2023/01
Times Cited Count：3 Percentile：88.42(Physics, Multidisciplinary)
ambient on threshold voltage stability in 4H-SiC metal-oxide-semiconductor field-effect transistorsHosoi, Takuji*; Osako, Momoe*; Moges, K.*; Ito, Koji*; Kimoto, Tsunenobu*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Applied Physics Express, 15(6), p.061003_1 - 061003_5, 2022/06
Times Cited Count：2 Percentile：34.67(Physics, Applied)The combination of NO annealing and subsequent post-nitridation annealing (PNA) in CO ambient for SiO/SiC structures has been demonstrated to be effective in obtaining both high channel mobility and superior threshold voltage stability in SiC-based metal-oxide-semiconductor field-effect transistors (MOSFETs). N atoms on the SiO side of the SiO/SiC interface incorporated by NO annealing, which are plausible cause of charge trapping sites, could be selectively removed by CO-PNA at 1300
C without oxidizing the SiC. CO-PNA was also effective in compensating oxygen vacancies in SiO, resulting high immunity against both positive and negative bias-temperature stresses.
/4H-SiC(11
0) interfacesNakanuma, Takato*; Iwakata, Yu*; Watanabe, Arisa*; Hosoi, Takuji*; Kobayashi, Takuma*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Japanese Journal of Applied Physics, 61(SC), p.SC1065_1 - SC1065_8, 2022/05
Times Cited Count：7 Percentile：77.62(Physics, Applied)Nitridation of SiO/4H-SiC(110) interfaces with post-oxidation annealing in an NO ambient (NO-POA) and its impact on the electrical properties were investigated. Sub-nm-resolution nitrogen depth profiling at the interfaces was conducted by using a scanning X-ray photoelectron spectroscopy microprobe. The results showed that nitrogen atoms were incorporated just at the interface and that interface nitridation proceeded much faster than at SiO/SiC(0001) interfaces, resulting in a 2.3 times higher nitrogen concentration. Electrical characterizations of metal-oxide-semiconductor capacitors were conducted through capacitance-voltage (
) measurements in the dark and under illumination with ultraviolet light to evaluate the electrical defects near the conduction and valence band edges and those causing hysteresis and shifting of the curves. While all of these defects were passivated with the progress of the interface nitridation, excessive nitridation resulted in degradation of the MOS capacitors. The optimal conditions for NO-POA are discussed on the basis of these experimental findings.
0) MOS devicesNakanuma, Takato*; Kobayashi, Takuma*; Hosoi, Takuji*; Sometani, Mitsuru*; Okamoto, Mitsuo*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Applied Physics Express, 15(4), p.041002_1 - 041002_4, 2022/04
Times Cited Count：5 Percentile：48.5(Physics, Applied)The leakage current and flat-band voltage (VFB) instability of NO-nitrided SiC (110) (a-face) MOS devices were systematically investigated. Although NO nitridation is effective in improving the interface properties, we found that it reduces the onset field of Fowler-Nordheim (F-N) current by about 1 MVcm
, leading to pronounced leakage current. Synchrotron X-ray photoelectron spectroscopy revealed that the nitridation reduces the conduction band offset at the SiO/SiC interface, corroborating the above finding. Furthermore, systematical positive and negative bias stress tests clearly indicated the VFB instability of nitrided a-face MOS devices against electron and hole injection.
Mochimaru, Takanori*; Koizumi, Mitsuo; Takahashi, Tone; Hironaka, Kota; Kimura, Yoshiki; Sato, Yuki; Terasaka, Yuta; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*
Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11
no abstracts in English
SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.
Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03
Times Cited Count：4 Percentile：57.13(Physics, Nuclear)
-ray pipe-monitoring capabilities for real-time process monitoring safeguards applications in reprocessing facilitiesRodriguez, D.; Tanigawa, Masafumi; Nishimura, Kazuaki; Mukai, Yasunobu; Nakamura, Hironobu; Kurita, Tsutomu; Takamine, Jun; Suzuki, Satoshi*; Sekine, Megumi; Rossi, F.; et al.
Journal of Nuclear Science and Technology, 55(7), p.792 - 804, 2018/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear material in reprocessing facilities is safeguarded by random sample verification with additional continuous monitoring applied to solution masses and volume in important tanks to maintain continuity-of-knowledge of process operation. Measuring the unique rays of each solution as the material flows through pipes connecting all tanks and process apparatuses could potentially improve process monitoring by verifying the compositions in real time. We tested this ray pipe-monitoring method using plutonium-nitrate solution transferred between tanks at the PCDF-TRP. The rays were measured using a lanthanum-bromide detector with a list-mode data acquisition system to obtain both time and energy of -ray. The analysis and results of this measurement demonstrate an ability to determine isotopic composition, process timing, flow rate, and volume of solution flowing through pipes, introducing a viable capability for process monitoring safeguards verification.
Zr and a large 
value between the 
and 
statesSugawara, Masahiko*; Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi*; Kimura, Atsushi; Kin, Tadahiro*; Hatsukawa, Yuichi*; Kusakari, Hideshige*
Physical Review C, 96(2), p.024314_1 - 024314_7, 2017/08
Times Cited Count：1 Percentile：10.45(Physics, Nuclear) ray in aerial radiation monitoringIshizaki, Azusa; Sanada, Yukihisa; Mori, Airi; Imura, Mitsuo; Ishida, Mutsushi; Munakata, Masahiro
Remote Sensing, 8(11), p.892_1 - 892_12, 2016/11
Times Cited Count：6 Percentile：26.95(Environmental Sciences)In aerial radiation monitoring (ARM), the air dose rate cannot be appropriately estimated under snowy conditions due to attenuation of ray by the snow layer. A technique to address this issue is required for ARM to obtain enough signals for air dose rate. To develop this technique, we investigated the relationship between snow depth and ARM measurement results using ARM, laser imaging detection and ranging, and ground measurement before and after snowfall. From the measured data, the results obtained using three different correction factors were examined and compared. An appropriate correction improved the underestimation of the air dose rate. However, further improvement in the accuracy of the analysis require accurate estimation of the snow water equivalent.
Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.
JAEA-Research 2016-016, 131 Pages, 2016/10
JAEA-Research-2016-016.pdf:20.59MB
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.
Kimura, Atsushi; Harada, Hideo; Nakamura, Shoji; Iwamoto, Osamu; Toh, Yosuke; Koizumi, Mitsuo; Kitatani, Fumito; Furutaka, Kazuyoshi; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
European Physical Journal A, 51(12), p.180_1 - 180_8, 2015/12
Times Cited Count：3 Percentile：30.26(Physics, Nuclear)Sanada, Yukihisa; Mori, Airi; Ishizaki, Azusa; Munakata, Masahiro; Nakayama, Shinichi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika; Yamada, Tsutomu; Ishida, Mutsushi; et al.
JAEA-Research 2015-006, 81 Pages, 2015/07
JAEA-Research-2015-006.pdf:22.96MB
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report.
SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Harada, Hideo; Kimura, Atsushi; Kitatani, Fumito; Koizumi, Mitsuo; Tsuchiya, Harufumi; Becker, B.*; Kopecky, S.*; Schillebeeckx, P.*
Journal of Nuclear Science and Technology, 52(6), p.837 - 843, 2015/06
Times Cited Count：3 Percentile：25.85(Nuclear Science & Technology)) reactions with the ANNRI-Cluster Ge detectors at J-PARCHara, Kaoru; Goko, Shinji*; Harada, Hideo; Hirose, Kentaro; Kimura, Atsushi; Kin, Tadahiro*; Kitatani, Fumito; Koizumi, Mitsuo; Nakamura, Shoji; Toh, Yosuke; et al.
JAEA-Conf 2014-002, p.88 - 92, 2015/02
Takamine, Jun; Koizumi, Mitsuo; Kureta, Masatoshi; Harada, Hideo; Kitatani, Fumito; Tsuchiya, Harufumi; Seya, Michio; Iimura, Hideki
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 10 Pages, 2015/01
A prototype device of neutron resonance densitometry (NRD) with a D-T neutron generator was planned for basic studies of actual NRD devices. D-T neutron generators had features of simple handling and compact compared with photo neutron sources driven by electron beam accelerators. But those of D-T neutron are higher energy and lower intensity than those of photo neutron. We designed a new type moderator to compensate for the shortcomings. In the new type moderator, the D-T neutron generator is surrounded by Lead, and Polyethylene is arranged in the beam direction on the surface of Lead. As the result of analysis using Monte Carlo code MCNP5, it was found that the new moderator achieved about four times larger production of low energy neutrons than polyethylene moderator without distorting the energy resolution below at least 100 eV. The lead part in the new moderator are changed to other heavy metals, which is Uranium, and Tungsten. Analysis like the above were performed. We report these results.
Tsuchiya, Harufumi; Harada, Hideo; Koizumi, Mitsuo; Kitatani, Fumito; Takamine, Jun; Kureta, Masatoshi; Iimura, Hideki; Kimura, Atsushi; Becker, B.*; Kopecky, S.*; et al.
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01
We are developing neutron resonance densitometry that combines neutron resonance transmission analysis (NRTA) and neutron resonance capture analysis. The aim is to establish a non-destructive technique that can quantify nuclear materials in particle-like debris of melted fuel resulting from severe nuclear accidents like the one at the Fukushima Daiichi Nuclear Power Plant. Systematic effects due to sample thickness and mixed sample for the areal density measurement by NRTA were investigated at a neutron time-of-facility GELINA, IRMM. The experiments were conducted utilizing natural Cu metal discs with different thickness and a B
C disc. Areal densities were derived with a resonance shape analysis code REFIT. It was found that they were inconsistent with those calculated by mass and area, when using recommended resonance parameters. Hence, a neutron width of resonance parameters was newly evaluated with the NRTA data and we found that derived areal density agreed within 2% with the expected ones. We also discuss the impacts of mixed sample for the areal density derived from NRTA measurement.
scintillation detector system for neutron resonance densitometryKoizumi, Mitsuo; Tsuchiya, Harufumi; Kitatani, Fumito; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Seya, Michio; Kimura, Atsushi; Iimura, Hideki; Becker, B.*; et al.
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2015/01
We have proposed neutron resonance densitometry (NRD) as a method to quantify special nuclear materials in particle-like debris of melted fuel. NRD is a combination of neutron resonance transmission analysis (NRTA), and neutron resonance capture analysis (NRCA) (and prompt -ray analysis (PGA)). NRCA/PGA is used to identify contaminant elements, which is difficult to be detected by NRTA. To observe rays emitted in neutron capture reaction, a spectrometer consisting of LaBr
scintillation detectors has been constructed. A newly installed data acquisition system enables us to measure 500 k event/s for each 8-channel inputs. In this presentation, the research and development of NRD is introduced and the status of the development of the spectrometer system is given as well.
Koizumi, Mitsuo; Kitatani, Fumito; Tsuchiya, Harufumi; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Iimura, Hideki; Seya, Michio; Becker, B.*; Kopecky, S.*; et al.
Nuclear Back-end and Transmutation Technology for Waste Disposal, p.13 - 20, 2015/00
Neutron Resonance Densitometry (NRD) has been proposed for quantification of nuclear materials in melted fuel. NRD is a combined TOF technique of Neutron Resonance Transmission Analysis (NRTA) and Neutron Resonance Capture Analysis (NRCA) or Prompt Gamma ray Analysis (PGA). To establish the method, development of detectors is in progress. Experiments were carried out at a TOF facility, GELINA, under the collaboration with EC-JRC-IRMM. The progress of the project is reported.
Toh, Yosuke; Ebihara, Mitsuru*; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo; Hara, Kaoru*; Koizumi, Mitsuo; Kitatani, Fumito; Furutaka, Kazuyoshi
Analytical Chemistry, 86(24), p.12030 - 12036, 2014/12
Times Cited Count：18 Percentile：55.18(Chemistry, Analytical)Non-destructive elemental analyses have been an indispensable tool for many fields of scientific research. Prompt -ray analysis and time of flight elemental analysis uses the energy of the rays and the energy of neutron resonances, respectively. In both analyses, a sample is irradiated with neutrons and rays are detected. Thus, these methods are similar and could be replaced by a single measurement. However, these methods have never been applied simultaneously before. We have first developed a novel technique which combines these methods by using an intense pulsed neutron beam. It allows us to obtain the results from both methods at the same time. Moreover, significant synergy has been achieved. Specifically, it will be used to quantify elemental concentrations in the sample that neither of these methods can be applied. Here, we demonstrate how it can be used to extract reliable information from unresolved peaks in the spectra.
