JOPSS - Search Results

Journal Articles

Radiation-induced currents in 4H-SiC dosimeters for real-time -ray dose rate monitoring

Fujita, Natsuko; Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi

Materials Science Forum, 778-780, p.1042 - 1045, 2014/02

https://doi.org/10.4028/www.scientific.net/MSF.778-780.1042

Times Cited Count：1 Percentile：53.56(Crystallography)

A Silicon Carbide (SiC) dosimeter has been exposed to -rays emitted from a $^{60}$ Co source in order to test the response of radiation-induced current in the dose rate ranging from 0.4 Gy/h to 4 kGy/h. The SiC dosimeter in this study is a high purity semi-insulating 4H-SiC with nickel and aluminum electrode. The radiation-induced currents in the dosimeter show a linear relationship with the dose rate, and are repeatable and stable.

Journal Articles

Defect levels in high purity semi-insulating 4H-SiC studied by alpha particle induced charge transient spectroscopy

Iwamoto, Naoya; Onoda, Shinobu; Fujita, Natsuko; Makino, Takahiro; Oshima, Takeshi

Materials Science Forum, 778-780, p.289 - 292, 2014/02

https://doi.org/10.4028/www.scientific.net/MSF.778-780.289

Times Cited Count：0 Percentile：0.32(Crystallography)

Journal Articles

Kinetic behavior of water as migration media in compacted montmorillonite using H $_{2}$ $^{18}$ O and applying electric potential gradient

Tanaka, Shingo*; Noda, Natsuko*; Higashihara, Tomohiro*; Sato, Seichi*; Kozaki, Tamotsu*; Sato, Haruo; Hatanaka, Koichiro

Physics and Chemistry of the Earth, 33(Suppl.1), p.S163 - S168, 2008/00

In order to identify mass transport pathway in compacted bentonite, water transport behavior in compacted montmorillonite which is the major clay mineral constituent of the bentonite was studied. Back-to-back diffusion and electro-osmosis experiments for H $_{2}$ O were carried out at montmorillonite densities of 1.0, 1.2 and 1.4 Mg/m $^{3}$ using H $_{2}$ $^{18}$ O as a tracer. Apparent diffusivities from the diffusion experiments and advection velosities and hydraulic dispersities from the electro-osmosis experiments were determined. The mass transport pathways were discussed by comparing with concentration profiles and peak positions of He, Na and Cl which were reported in the past. The hydraulic dispersities decreased in the order of He, H $_{2}$ O, Cl and Na, and these differences were considered to be due to that transport pathway depended on species and hydraulic dispersity for each species also depended on transport pathway.

Oral presentation

Dependence of water diffusion on water to cement ratio in ordinary portland cement pastes

Takiya, Hiroaki*; Tanaka, Shingo*; Noda, Natsuko*; Sato, Seichi*; Kozaki, Tamotsu*; Sato, Haruo; Hatanaka, Koichiro

no journal, ,

It is important to clarify the behaviour of cement porewater for performance assessment of radioactive waste disposal. In this study, we measured apparent self-diffusion coefficients of water in Ordinary Portland Cement pastes with various water-cement ratios (W/C) as the part. The diffusion experiments were carried out as a function of W/C ratio in a range of 0.4-0.8, and O-18 was used as a tracer of water. The apparent diffusion coefficient increased with W/C. All penetration profiles of O-18 showed a tendency to shift from simple diffusion profile with increasing diffusion depth. It was indicated existence of some different diffusion pathways.

Oral presentation

Electrochemical study on migration of ions in water-saturated, compacted sodium montmorillonite; Effects of dry density and salinity

Tanaka, Shingo*; Noda, Natsuko*; Sato, Seichi*; Kozaki, Tamotsu*; Sato, Haruo; Hatanaka, Koichiro

no journal, ,

Migration experiments for an anion (Cl), a cation (Na) and water (HTO, HO) in compacted Na-montmorillonite were carried out under electro-potential gradient, and mobility, diffusion length and transport number of each ion were obtained as a function dry density (0.8-1.6Mg/m). The apparent diffusion coefficients of Na and Cl ion were obtained based on the experiments and it was indicated that the diffusion mechanism between both ions was different. For transport number, the transport number of Na ion was 1 when NaCl concentration was 0, and this indicates that Na ion which is exchangeable cation of the Na-montmorillonite carries all charges, meanwhile, the transport number of Na ion decreased with increasing NaCl concentration and that of Cl ion instead increased. This indicates that the diffusion property of Na ion decreases with increasing salinity and instead that of Cl ion increases, and it is in good agreement with many facts reported so far.

We investigate the threshold voltage shift of Si-MOSFETs, SiC-MOSFETs, SiC-MESFETs, and SiC SITs (Static Induction Transistors) due to irradiation. As a result, no significant threshold voltage shift was observed up to the absorbed dose of 10 Gy in all the SiC transistors, whereas the serious degradation was observed in the Si-MOSFETs. This strongly indicates that radiation resistance of SiC-MOSFETs and the other SiC-transistors is far superior to that of Si-MOSFETs. The radiation resistance of SiC-MOSFETs fabricated by pyrogenic oxidation is higher than that of the SiC-MOSFETs fabricated by dry oxidation. This result reflects that radiation resistance of SiC-MOSFETs strongly depends on the gate oxidation process since the formed oxide layers have different properties. Also, radiation resistance of SiC-SITs and SiC MESFETs is higher than that of SiC-MOSFETs, since SITs and MESFETs do not have gate oxide layer.

Presentation/Publication Type

Journal/Book Title

Meeting title

First Author

Keyword

Language

Publication Year

Held year of conference

Radiation-induced currents in 4H-SiC dosimeters for real-time -ray dose rate monitoring

Defect levels in high purity semi-insulating 4H-SiC studied by alpha particle induced charge transient spectroscopy

Kinetic behavior of water as migration media in compacted montmorillonite using H $_{2}$ $^{18}$ O and applying electric potential gradient

Dependence of water diffusion on water to cement ratio in ordinary portland cement pastes

Electrochemical study on migration of ions in water-saturated, compacted sodium montmorillonite; Effects of dry density and salinity

Development of real-time -ray dose rate dosimeter with 4H-SiC

Oxidation condition dependence of radiation effects on 4H-SiC MOS capacitors

Defects in HPSI 4H-SiC studied by alpha particles induced charge transient spectroscopy

Development of a new defect level characterization technique using heavy ion microbeams for wide bandgap semiconductors

Evaluation of radiation-induced currents and dose rate dependence in 4H-SiC

Change in electrical properties SiC-MOS capacitor and PiN diode after ray irradiation

Degradation of I-V characteristics of SiC-MOSFET caused by rays from Co-60

Decrease in semi-insulating properties of HPSI 4H-SiC substrates by high temperature annealing

Single event gate rupture on -ray irradiated 4H-SiC MOS capacitors

ray irradiation dose dependence of electrical characterizations of SiC-MOS capacitors

Impact on I-V characteristics of Si- and SiC-MOSFETs caused by ray

-ray irradiation response of silicon carbide semiconductor devices; Extremely high radiation resistance