A Development of super radiation-hardened power electronics using silicon carbide semiconductors; Toward MGy-class radiation resistivity

Hijikata, Yasuto*; Mitomo, Satoshi*; Matsuda, Takuma*; Murata, Koichi*; Yokoseki, Takashi*; Makino, Takahiro; Takeyama, Akinori; Onoda, Shinobu; Okubo, Shuichi*; Tanaka, Yuki*; et al.

Proceedings of 11th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-11) (Internet), p.130 - 133, 2015/11

Study of oxide film with the hard X-ray photoelectron spectroscopy

Kobata, Masaaki; Kobayashi, Keisuke*

Journal of the Vacuum Society of Japan, 58(2), p.43 - 49, 2015/02

https://doi.org/10.3131/jvsj2.58.43

We report the applications of a hard X-ray photoelectron spectroscopy to the characterization of SiO/Si(001)systems. Large escape depth of high-energy photoelectron enables us to probe buried layers and their interfaces in multilayer structures. Estimation of SiO overlayer thicknesses up to 25 nm by angle resolved XPS was possible in SiO/Si(001) samples. Determination of the thickness profile of a wedged shape SiO buried layer was successfully done in Ir (8 nm)/HfO (2.2 nm)/thickness graded-SiO (0-10 nm) / Si (100). The Si 1s core level showed a SiO thickness dependent shift, which was ascribed to fixed charge at the SiO-Si interface. Energy distribution of interface states at ultrathin thermal oxide/Si(100) interfaces were determined by Si 1 core level shift by applying gate bias in metal-oxide-semiconductor (MOS) structure with 5 nm Au gate electrodes.

Application of hydrogen analysis by neutron imaging plate method to Zircaloy cladding tubes

Yasuda, Ryo; Nakata, Masahito; Matsubayashi, Masahito; Harada, Katsuya; Hatakeyama, Yuichi; Amano, Hidetoshi

Journal of Nuclear Materials, 320(3), p.223 - 230, 2003/08

https://doi.org/10.1016/S0022-3115(03)00112-0

Neutron radiography is one of effective tools to determine hydrided region in Zircaloy cladding tubes. In this work, the practicability of the neutron radiography for hydrogen analysis is further investigated by using standard samples with known hydrogen concentration. Local hydrogen concentration in hydrided Zircaloy tube is quantitatively estimated using the standard samples by neutron imaging plate (NIP) method. The local area is equivalent to a picture element in the image; e.g., 0.1mm0.1mm. In addition, contribution of an oxide film in the tubes to the images is investigated using oxidized samples with hydrides or no hydride. In NIP images of oxidized tube no oxide film was recognized. Numerical image analysis also shows no effect of the oxide film on the image. These results show that the influence of oxygen on image contrast can be neglected when hydrogen analysis is performed on the Zircaloy tube with oxide film and hydrides by NIP method.

Effect of cladding pre-oxidation on rod coolability during reactivity accident conditions

Sugiyama, Tomoyuki; Fuketa, Toyoshi

IAEA-TECDOC-1320, p.102 - 110, 2002/11

http://www-pub.iaea.org/MTCD/Publications/PDF/te_1320_web/attention.pdf

This report discusses effect of cladding surface pre-oxidation on fuel rod coolability during reactivity initiated accident (RIA) conditions. NSRR irradiated fuel experiments had shown cladding surface temperature lower than fresh fuel experiments. One possible speculation for the temperature difference is that oxide layer at the cladding outer surface enhanced heat transfer. To verify the speculation, pulse irradiation tests were performed on fuel rods with three different surface conditions: without oxide layer, with 1m-thick and 10m-thick oxide layer. Transient records of the cladding surface temperature showed the critical heat flux and the minimum heat flux increased for the oxidized fuel rods. These effects depend on presence of the oxide layer, not on the thickness of the layer, because no difference existed between results from 1m and 10m rods.

Ion beam induced charge gate rupture of oxide on 6H-SiC

Lee, K. K.; Nishijima, Toshiji*; Oshima, Takeshi; Jamieson, D. N.*

Nuclear Instruments and Methods in Physics Research B, 181(1-4), p.324 - 328, 2001/07

https://doi.org/10.1016/S0168-583X(01)00622-X

Investigation of oxide charge trapping and interface state generation in SiO grown on 6H-SiC was performed using ion beam induced charge (IBIC), electroluminescence (EL) and the high frequency capacitance-voltage (CV) method. A large flatband voltage shift in CV measurements indicated a high density of positive charges trapped near the SiC/SiO interface. These trapped charges were related to defects either existing in the oxide or generated during alpha particle irradiation. EL indicated trap levels at 1.36, 1.6, 2.3 and 2.9 eV. Levels at 1.36 and 2.3 eV are defects existing in the SiC substrate, while the other two remaining levels are due to defects in the oxide. These defects affected the radiation hardness of SiC electronic devices. Oxide rupture caused by alpha particle irradiation of the metal-oxide-p-type SiC device is observed.

Decay heat removal analyses on the heavy liquid metal cooled fast breeding reactor; Comparisons of the decay heat removal characteristics on Lead, Lead-Bismuth and Sodium cooled reactors

Sakai, Takaaki; *; Ohshima, Hiroyuki; Yamaguchi, Akira

JNC TN9400 2000-033, 94 Pages, 2000/04

JNC-TN9400-2000-033.pdf:4.36MB

The feasibility study on several concepts for the commercial fast breeder reactor(FBR) in future has been conducted in JNC for the kinds of possible coolants and fuel types to confirm the direction of the FBR developments in Japan. ln this report, Lead and Lead-Bismuth eutectic coolants were estimated for the decay heat removal characteristics by the comparison with sodium coolant that has excellent features for the heat transfer and heat transport performance. Heavy liquid metal coolants, such as Lead and Lead-Bismuth, have desirable chemical inertness for water and atmosphere. Therefore, there are many economical plant proposals without an intermediate heat transport system that prevents the direct effect on a reactor core by the chemical reaction between water and the liquid metal coolant at the hypocritical tube fairer accidents in a steam generator. ln this study, transient analyses on the thermal-hydraulics have been performed for the decay heat removal events in "Equivalent plant" with the Lead, Lead-Bismuth and Sodium coolant by using Super-COPD code. And a resulted optimized lead cooled plant in feasibility study was also analyzed for the comparison. ln conclusion, it is become clear that the natural circulation performance, that has an important roll in passive safety characteristic of the reactor, is more excellent in heavy liquid metals than sodium coolant during the decay heat removal transients. However, we need to conform the heat transfer reduction by the oxidize film or the corrosion products expected to appear on the heat transfer surface in the Lead and Lead-Bismuth circumstance.

Radiation-induced trapped charge in metal-nitride-oxide-semiconductor structure

Takahashi, Yoshihiro*; Onishi, Kazunori*; Fujimaki, Takeshi*; Yoshikawa, Masahito

IEEE Transactions on Nuclear Science, 46(6), p.1578 - 1585, 1999/12

https://doi.org/10.1109/23.819124

no abstracts in English

None

*; *; ; Takeda, Seiichiro

PNC TN8410 97-433, 49 Pages, 1997/12

PNC-TN8410-97-433.pdf:1.44MB

None

None

Ohara, Hiroshi*; *

PNC TJ8164 96-009, 261 Pages, 1996/09

PNC-TJ8164-96-009.pdf:12.32MB

no abstracts in English

Evaluation of the charge distribution in the oxide of MOS structure before and after -ray radiation

*; *; Takahashi, Yoshihiro*; Yoshikawa, Masahito; Onishi, Kazunori*

Denshi Joho Tsushin Gakkai Gijutsu Kenkyu Hokoku, 93(172), p.23 - 27, 1993/07

no abstracts in English