Evaluation and mitigation of reactive ion etching-induced damage in AlGaN/GaN MOS structures fabricated by low-power inductively coupled plasma

Nozaki, Mikito*; Terashima, Daiki*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*

Japanese Journal of Applied Physics, 59(SM), p.SMMA07_1 - SMMA07_7, 2020/07

https://doi.org/10.35848/1347-4065/ab8f0e

AlGaN/GaN metal-oxide-semiconductor (MOS) structures were fabricated by low-power inductively coupled plasma reactive ion etching and chemical vapor deposition of SiO dielectrics on the etched surfaces, and they were systematically investigated by physical and electrical characterizations in an effort to develop a low-damage recessed gate process. The comprehensive research demonstrates the significant advantages of the proposed low-damage recessed gate process for fabricating next-generation AlGaN/GaN MOS-HFET devices.

Europium binding to humic substances extracted from deep underground sedimentary groundwater studied by time-resolved laser fluorescence spectroscopy

Saito, Takumi*; Aoyagi, Noboru; Terashima, Motoki

Journal of Nuclear Science and Technology, 54(4), p.444 - 451, 2017/04

https://doi.org/10.1080/00223131.2016.1274688

Humic substances (HSs) are ubiquitous in various environments including deep underground and play an important role in the speciation and mobility of radionuclides. The binding of Eu, a chemical homologue of trivalent actinide ions, to HSs isolated from sedimentary groundwater at -250 m below the surface was studied by time-resolved laser fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) as a function of pH and salt concentration. PARAFAC modeling reveals the presence of multiple factors that corresponds to different Eu species. These factors resemble those observed for Eu binding to HSs from surface environments; however, detailed comparison shows that there are some particularities in Eu binding to the deep groundwater HSs. The distribution coefficients () of Eu binding to the HSs calculated from the PARAFAC modeling exhibits a rather strong salt effect. At 0.01 M NaClO the values are relatively large and comparable to those to the surface HSs; they are decreaed at 0.1 M NaClO by more than an order of the magnitude. The values are larger for humic acid fraction of the deep underground HSs than fulvic acid over the entire range of pH and salt concentration investigated in this study.

Physicochemical and ion-binding properties of highly aliphatic humic substances extracted from deep sedimentary groundwater

Saito, Takumi; Terashima, Motoki; Aoyagi, Noboru; Nagao, Seiya*; Fujitake, Nobuhide*; Onuki, Toshihiko

Environmental Science; Processes & Impacts, 17(8), p.1386 - 1395, 2015/08

https://doi.org/10.1039/C5EM00176E

The deep groundwater HSs were different from surface HSs, having high aliphaticities, sulfur contents, and small molecular sizes. The amounts of their acidic functional groups were comparable to or slightly larger than those of surface HSs; however, the magnitude of Cu binding to the deep groundwater HSs was smaller. The NICA-Donnan model attributed this to the binding of Cu to chemically homogeneous carboxylic-type sites via mono-dentate coordination at relatively low pH. The binding mode tended to shift to multi-dentate coordination with carboxylic-type and probably more heterogeneous alcoholic hydroxide-type groups at higher pH. This study shows the particularity of the deep groundwater HSs in terms of their physicochemical and ion-binding properties, compared with surface HSs.

Investigation for colloids in the groundwater of Horonobe URL, 1; Characterization of colloids in the groundwater by using ultra filtration

Amano, Yuki; Amamiya, Hiroki; Murakami, Hiroaki; Iwatsuki, Teruki; Terashima, Motoki; Mizuno, Takashi; Kirishima, Akira*; Kuno, Atsushi*; Sasaki, Takayuki*; Kubota, Takumi*; et al.

no journal, , 

no abstracts in English

Loading effect on Eu(III) binding to groundwater humic acid; Application of NICA-Donnan model

Terashima, Motoki; Saito, Takumi; Ishii, Tomoko*; Akagi, Yosuke*; Tachi, Yukio

no journal, , 

no abstracts in English

Modeling of Eu binding by dissolved organic matters in groundwater

Terashima, Motoki; Saito, Takumi*; Akagi, Yosuke*; Endo, Takashi*

no journal, , 

no abstracts in English

Effect of humic substances on the sorption and diffusion of Eu(III) in sedimentary rock

Terashima, Motoki; Tachi, Yukio; Saito, Takumi*; Iijima, Kazuki; Shimoda, Satoko*; Nakazawa, Toshiyuki*; Yoshikawa, Hideki

no journal, , 

no abstracts in English

Metal ion complexation to deep groundwater humic substances

Saito, Takumi; Terashima, Motoki

no journal, , 

no abstracts in English

SiO/AlON stacked gate dielectrics for AlGaN/GaN MOS-HFET

Watanabe, Kenta*; Terashima, Daiki*; Nozaki, Mikito*; Yamada, Takahiro*; Nakazawa, Satoshi*; Ishida, Masahiro*; Anda, Yoshiharu*; Ueda, Tetsuzo*; Yoshigoe, Akitaka; Hosoi, Takuji*; et al.

no journal, , 

The advantage of SiO/AlON stacked gate dielectrics over SiO, AlON and AlO single dielectric layers was demonstrated. Our systematic research revealed that the optimized stacked structure with 3.3-nm-thick AlON interlayer is beneficial in terms of superior interface quality, reduced gate leakage current and C-V hysteresis for next-generation high frequency and high power AlGaN/GaN MOS-HFETs.

Current status of the HIBMC, providing particle beam radiation therapy for more than 2,600 patients, and the prospects of laser-driven proton radiotherapy

Murakami, Masao*; Demizu, Yusuke*; Niwa, Yasue*; Nagayama, Shinichi*; Maeda, Takuya*; Baba, Masashi*; Miyawaki, Daisuke*; Terashima, Kazuki*; Arimura, Takeshi*; Mima, Masayuki*; et al.

no journal, ,