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Hosoi, Takuji*; Kirino, Takashi*; Uenishi, Yusuke*; Ikeguchi, Daisuke*; Chanthaphan, A.*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; et al.
Workshop digest of 2012 Asia-Pacific Workshop on Fundamentals and Applications of Advanced Semiconductor Devices (AWAD 2012), p.22 - 25, 2012/06
/4H-SiC interfaceHosoi, Takuji*; Kirino, Takashi*; Chanthaphan, A.*; Uenishi, Yusuke*; Ikeguchi, Daisuke*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; et al.
Materials Science Forum, 717-720, p.721 - 724, 2012/05
Times Cited Count：6 Percentile：92.08(Materials Science, Multidisciplinary)Watanabe, Heiji*; Hosoi, Takuji*; Kirino, Takashi*; Uenishi, Yusuke*; Chanthaphan, A.*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; et al.
Materials Science Forum, 717-720, p.697 - 702, 2012/05
Times Cited Count：3 Percentile：80.24(Materials Science, Multidisciplinary)/4H-SiC(0001) interface and its correlation with electrical propertiesWatanabe, Heiji*; Hosoi, Takuji*; Kirino, Takashi*; Kagei, Yusuke*; Uenishi, Yusuke*; Chanthaphan, A.*; Yoshigoe, Akitaka; Teraoka, Yuden; Shimura, Takayoshi*
Applied Physics Letters, 99(2), p.021907_1 - 021907_3, 2011/07
Times Cited Count：126 Percentile：95.42(Physics, Applied) gate dielectrics for SiC power devicesWatanabe, Heiji*; Kirino, Takashi*; Uenishi, Yusuke*; Chanthaphan, A.*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
ECS Transactions, 35(2), p.265 - 274, 2011/05
Times Cited Count：8 Percentile：91.96(Electrochemistry)/4H-SiC interfaces and its modulation induced by intrinsic and extrinsic interface charge transferWatanabe, Heiji*; Kirino, Takashi*; Kagei, Yusuke*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
Materials Science Forum, 679-680, p.386 - 389, 2011/03
Times Cited Count：29 Percentile：99.49(Engineering, Multidisciplinary)Watanabe, Heiji*; Hosoi, Takuji*; Kirino, Takashi*; Uenishi, Yusuke*; Chanthaphan, A.*; Ikeguchi, Daisuke*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; et al.
ECS Transactions, 41(3), p.77 - 90, 2011/00
Times Cited Count：6 Percentile：91.39(Electrochemistry)/4H-SiC interfaces and its modulation induced by post-oxidation treatmentsKirino, Takashi*; Kagei, Yusuke*; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*
no journal, ,
stacked dielectricsWatanabe, Heiji*; Kagei, Yusuke*; Kosono, Kohei*; Kirino, Takashi*; Watanabe, Yu*; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.
no journal, ,
SiC-MOSFET's are expected for normally-off-type high performance power devices. Electrical defects due to residual inpurities such as carbon are in the interface of thermally-oxidized SiC-MOS's so that channel mobility is degraded preferentially. Although upgrade of reliability of a gate insulator is necessary for practical use, insulator degradation mechanisms have not well known yet. We are studying high quality MOS interface made by plasma nitridation techniques, upgrade of reliability and insulation by a stuck structure of a high-k insulator (AlON) layer and an SiO underlayer. Recent research results on those subjects are reported in this talk.
Nakashima, Satoru*; Kirino, Yusuke*; Nishiyama, Naoki*; Tonoue, Ryota*; Yokoyama, Tadashi*; Nagasawa, Makoto*; Harui, Rika*; Walker, C.; Sasamoto, Hiroshi
no journal, ,
Cementitious grout material will be used to reduce groundwater inflow into the repository of high level radioactive waste. High pH solution derived from cementitious grout material may cause alteration of rock mass by grout-rock interactions. With regard to evaluation of radionuclide migration, it is important to evaluate the long-term behavior of rock mass affected by grout-rock interactions since such altered rock mass potentially affects on migration behavior (e.g., diffusion and sorption) of radionuclide. This study presents the results of identification for trace secondary minerals (alteration products) by (micro)infrared spectroscopy and determination of reaction rate constants of formation for secondary minerals.
/4H-SiC formed by thermal oxidationWatanabe, Heiji*; Kirino, Takashi*; Kagei, Yusuke*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
no journal, ,
Channel registibity of SiC-MOSFETs becomes larger with decreasing carrier mobility due to defects in the SiO/SiC interface. Although channel mobility is larger than that of 4H-SiC(0001)Si face in the MOSFET fabricated on the 4H-SiC(000-1)C face, degradation of reliability for an oxide layer is remarkable. Valence band off-set and interface level density of the SiO/SiC interface are different from the former 4H-SiC(0001)Si face. Physical origins for these characters has not known yet. Thus, in order to make clear the origin of reliability degradation and interface characteristics of (000-1)C face, the energy band structure and chemical bonding states of the SiO/SiC interface formed by thermal oxidation.
Kirino, Yusuke*; Nakashima, Satoru*; Yokoyama, Tadashi*; Sasamoto, Hiroshi
no journal, ,
Cementitious grout materials will be used to reduce groundwater inflow during excavation and construction of drifts for deep geological disposal of high lever radioactive waste. High alkaline solution derived from cementitious materials could alter the host rock surrounding the engineered barriers. In the present study, the experiments of interactions between the alkaline solution and the granitic rock (10 
10 5 mm block sample) were conducted to understand the evolution of rock properties. The surface of granitic block sample is assumed the fresh fracture surface and the inside of block sample is regarded as rock matrix. Evolution and distribution of alteration products were estimated by both the accelerated laboratory experiments and the computer simulations considering reactive-transport processes.
/SiC interfaces formed by thermal oxidation of 4H-SiC(000
) surfacesKirino, Takashi*; Kagei, Yusuke*; Okamoto, Gaku*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
no journal, ,
In order to study the origin of degradation for interface chracteristics and reliability of SiC(0001)C surfaces, chemical bonding states at SiO/SiC interfaces made on (000)
and (000)
surfaces have been analyzed by using a synchrotron radiation XPS method. Si2p
components were extracted from Si2p photoemission peaks. Sub-oxidea components were observed in addition to the SiC substrate and the oxide layer. In the interface of the oxide layer formed on the (000) surface, Si
component was small, higher oxidation number components were larger, and total amount od sub-oxides was larger comparing to that of the (000) surface. A binding energy for oxide formed on the (000) surface was shifted to 0.22 eV higher side comparing to that of the (000) surface. It indicates that band off-set of conduction band is small in the SiO/SiC interface.
/4H-SiC conduction band offset by SR-XPSKirino, Takashi*; Kagei, Yusuke*; Okamoto, Gaku*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
no journal, ,
It has been reported that hydrogen incorporation into thermally grown SiO/4H-SiC structures not only improves the interface quality, but also degrades the gate oxide reliability depending on SiC surface orientation. In this study, energy band diagrams of thermally grown SiO/4H-SiC(0001) and SiO/4H-SiC(000-1) structures with and without high-temperature hydrogen annealing were evaluated by synchrotron radiation X-ray photoelectron spectroscopy. The SiO band gap and valence band offset at SiO/SiC interface were extracted from O 1s energy loss spectra and valence band spectra, respectively. The obtained energy band diagrams revealed that conduction band offsets at SiO/SiC interfaces were decreased after the hydrogen annealing especially for 4H-SiC(000-1) substrates. This is one possible reason for the reliability degradation of 4H-SiC metal-oxide-semiconductor devices by hydrogen incorporation.
N
interface layer on EOT scaling in high-k/Ge gate stacksKutsuki, Katsuhiro*; Okamoto, Gaku*; Hideshima, Iori*; Uenishi, Yusuke*; Kirino, Takashi*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Hosoi, Takuji*; Shimura, Takayoshi*; et al.
no journal, ,
Direct deposition of ZrO films on Ge substrates and subsequent thermal oxidation results in an equivalent oxide thickness (EOT) of above 2 nm while obtaining good interface quality due to interfacial GeO formation. In this work, we proposed the use of GeN interlayer formed by high-density plasma nitridation for further EOT scaling because of its high resistance to oxidation and superior thermal stability. The structural modification of ZrO/GeN/Ge after oxidation was characterized by synchrotron-radiation X-ray photoelectron spectroscopy at BL23SU in SPring-8. Ge 3d core-level spectra revealed that the GeN interlayer was slightly oxidized after thermal oxidation at 823 K, but N 1s spectra remained almost unchanged. This indicates that the GeN interlayer is effective in suppressing interfacial oxidation, thus obtaining an EOT of 1.8 nm.
/4H-SiC interfaceKirino, Takashi*; Kagei, Yusuke*; Okamoto, Gaku*; Harries, J.; Yoshigoe, Akitaka; Teraoka, Yuden; Mitani, Shuhei*; Nakano, Yuki*; Nakamura, Takashi*; Hosoi, Takuji*; et al.
no journal, ,
Device ability of SiC-MOSFET's expected from physical data has not been achieved because channel resistance increases by mobility degradation due to Si0/SiC interface defects. Although high channel mobility is obtained in the MOSFET's made on a 4H-SiC(000-1)c face compared to them on a 4H-SiC(0001)Si face, reliability of an oxide film is preferential in the MOSFET's on a 4H-SiC(000-1)c face. Conduction band off-set of SiO/SiC interface and energy distribution of the interface level density are known to be different between MOSFET's on a 4H-SiC(000-1)c face and a 4H-SiC(0001)Si face. Physical origins for them are not known yet. In order to make clear the reasons for degradation of interface characteristics and reliability in the MOSFET's made on an SiC(000-1)c face, we evaluated chemical bonding states and energy band structures of SiO/SiC interfaces formed on an SiC(0001)Si face and an SiC(000-1)c face using synchrotron radiation photoemission spectroscopy.
