Mass transport in the PdCu phase structures during hydrogen adsorption and absorption studied by XPS under hydrogen atmosphere

Tang, J.*; Yamamoto, Susumu*; Koitaya, Takanori*; Yoshigoe, Akitaka; Tokunaga, Takuma*; Mukai, Kozo*; Matsuda, Iwao*; Yoshinobu, Jun*

Applied Surface Science, 480, p.419 - 426, 2019/06

https://doi.org/10.1016/j.apsusc.2019.02.180

Mass transports during hydrogen adsorption and absorption processes of PdCu alloys that has advantages of higher hydrogen diffusivity and economically lower-cost than the other Pd-alloys were studied. The research was made with a comparison of the well-known ordered phase of the bcc structure (the B2 phase) and a mixed phase of the fcc and B2 structures. ultrahigh vacuum X-ray photoelectron spectroscopy and ambient pressure X-ray photoelectron spectroscopy using synchrotron radiation were carried out to trace the chemical states of the Pd and Cu atoms as a function of temperatures. It is elucidated that the initial adsorption and absorption processes were similar in the two phases, but a hydrogen diffusion rate to the bulk was higher in the ordered phase than in the mixed one. We found the dynamics of the Pd and Cu atoms during the hydrogen adsorption/absorption processes largely depend on temperature. In the hydrogen atmosphere, the Pd atoms segregate at the surface below 373 K and Cu atoms segregate at the surface above 373 K. The present results agree well with the previous theoretical calculations and, thus, provide appropriate inputs toward developments of the hydrogen permeation materials.

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

Electrical properties of SiC MOSFETs irradiated with -rays at elevated temperature

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

no journal, , 

Silicon carbide (SiC) is expected to be applied to Metal-Oxide-Semiconductor (MOS) FETs used in harsh radiation environments to decommission TEPCO Fukushima Daiichi nuclear reactors. To develop radiation resistant SiC MOS FETs, clarification of their radiation response under elevated temperature is required. We measured capacitance-voltage (C-V) characteristics of SiC MOSFETs irradiated with -rays at 423 K in nitrogen atmosphere. The samples were vertical power 4H-SiC MOSFETs with the blocking voltage of 1200 V and the rated current of 20 A with the gate oxide thickness of 45 nm. Typical C-V curve of a SiC MOSFET irradiated even up to 5 kGy was shifted to negative voltage side, suggesting that the positive charges generated in gate oxide by irradiation. While, no significant change in the slope of the curve was observed, indicating that interface traps between the gate oxide and SiC were merely generated. The radiation response of SiC MOS FETs under elevated temperature predominantly depends on the amount of positive charges generated in the gate oxide.

Test facility for investigating cosmic ray effect on space applications

Nakagawa, Sohei; Matsuda, Makoto; Nakamura, Masahiko; Ishizaki, Nobuhiro; Kutsukake, Kenichi; Asozu, Takuhiro; Ikekame, Takuma; Kabumoto, Hiroshi; Otokawa, Yoshinori; Matsui, Yutaka; et al.

no journal, , 

no abstracts in English

Development of ion source and beam acceleration test in Tokai tandem accelerator

Kabumoto, Hiroshi; Asozu, Takuhiro; Matsui, Yutaka; Nakagawa, Sohei; Ikekame, Takuma; Kato, Yuta; Ishizaki, Nobuhiro; Kutsukake, Kenichi; Otokawa, Yoshinori; Nakamura, Masahiko; et al.

no journal, , 

no abstracts in English

Present status of JAEA-Tokai tandem accelerator

Matsui, Yutaka; Nakamura, Masahiko; Kutsukake, Kenichi; Kabumoto, Hiroshi; Asozu, Takuhiro; Otokawa, Yoshinori; Ikekame, Takuma; Nakagawa, Sohei; Kato, Yuta; Ishizaki, Nobuhiro; et al.

no journal, , 

no abstracts in English

Optimum structures for -ray radiation resistant SiC-MOSFETs

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

no journal, , 

Oxide thickness dependence of -ray irradiation response on Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) was investigated. As a result of irradiation, the threshold voltage V for both SiC MOSFETs with gate oxide of 30 nm or 60 nm thick shifted to negative voltage-side gently. However, the V for 60 nm thick more immediately decreased over 400 kGy. It is found that SiCMOSFETs with smaller thickness has a higher radiation tolerance.

-ray irradiation effect on SiC MOSFETs with gate-bias voltage

Murata, Koichi; Mitomo, Satoshi; Matsuda, Takuma; Yokoseki, Takashi; Makino, Takahiro; Abe, Hiroshi; Onoda, Shinobu; Okubo, Shuichi*; Tanaka, Yuki*; Kandori, Mikio*; et al.

no journal, , 

no abstracts in English