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Onuma, Toshiharu*; Miyashita, Atsumi; Yoshikawa, Masahito; Tsuchida, Hidekazu*; Iwasawa, Misako*
Heisei-21-Nendo Sentan Kenkyu Shisetsu Kyoyo Sokushin Jigyo "Chikyu Shimyureta Sangyo Senryaku Riyo Puroguramu" Riyo Seika Hokokusho, p.21 - 27, 2010/07
Silicon carbide, being a wide-band-gap semiconductor, is an attractive material in the development of electronic devices operated under extreme conditions such as high power, high temperature, and high radiation. SiC is particularly attractive for use in MOS technology because among the compound semiconductors only silicon carbide has the thermal oxide SiO
, which is a good insulator. However, it is known that SiO/SiC interfaces have a higher density of interface traps than SiO/Si interfaces and that the channel mobility of MOS devices is much lower than theoretically expected values. In order to improve these characteristics, it is important to understand the thermal oxidation process at the SiO/SiC interface. We performed large-scale first-principles molecular dynamics simulations of the SiO/SiC interface oxidation process. We also performed large-scale first-principles molecular dynamics simulations to generate amorphous SiO/SiC interface.
Bian, Z.*; Ishii, Hirotake*; Shimoda, Hiroshi*; Yoshikawa, Hidekazu*; Morishita, Yoshitsugu; Kanehira, Yoshiki; Izumi, Masanori
IEICE Transactions on Information and Systems, E90-D(6), p.963 - 974, 2007/06
Times Cited Count：4 Percentile：33.28(Computer Science, Information Systems)This study designed linecode marker, a new type of paper-based marker and proposed recognition, tracking algorithm for it in order to resolve these problems. In comparison of the conventional paper-based markers, such as square markers, circle markers, the linecode marker is not only just easier to set up in complex industrial environment, but also makes it possible to use AR in industrial plant. In order to evaluate the tracking accuracy, trackable distance of the proposed tracking method, an evaluation experiment was conducted in a large room. The experiment results show that: comparing with traditional marker-based tracking method, tracking possible distance extends extremely; tracking accuracy improved to a level of 20cm in 10m distance.
/SiC interface structure by the first-principles molecular dynamics simulationMiyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Tsuchida, Hidekazu*; Yoshikawa, Masahito
Materials Science Forum, 556-557, p.521 - 524, 2007/00
SiC semiconductor devices are expected to be used in severe environments. However, SiC devices don't present the theoretically expected performance. This is considered to be attributed to the SiO/SiC interface defects that reduce electrical characteristics of devices. To generate the real device interface structure with the computer simulation, it is important to construct the a-SiO structure on SiC. The slab model using 444 atoms for a-SiO on a 4H-SiC (0001) crystal layer was constructed by using first-principles MD simulation. The heating and rapid quenching method was carried out to make an a-SiO/SiC interface structure. The heating temperature, the heating time and the speed of rapid quenching is 4000 K, 3.0 ps and -1000 K/ps, respectively. The interatomic distance and the bond angles of SiO layers agreed well with the most probable values in bulk a-SiO, and there were no coordination defects in the neighborhood of the SiC substrate.
/4H-SiC(0001) interface oxidation process; From first-principlesOnuma, Toshiharu*; Miyashita, Atsumi; Iwasawa, Misako*; Yoshikawa, Masahito; Tsuchida, Hidekazu*
Materials Science Forum, 556-557, p.615 - 620, 2007/00
We performed the dynamical simulation of the SiO/4H-SiC(0001) interface oxidation process using first-principles molecular dynamics based on plane waves and the slab model supercells method. The heat-and-cool method is used to prepare the initial interface structure. In this structure, there is no transition oxide layer or dangling bond at the SiO/SiC interface. As the trigger of the oxidation process, the carbon vacancy is introduced in the SiC layer near the interface. The oxygen molecules are added one by one to the empty sphere in the SiO layer near the interface in the oxidation process simulation. The molecular dynamics simulation is carried out at 2500 K. The oxygen molecule is dissociated and forms bonds with the Si atom in the SiO layer. The atoms of Si in the SiC layer at the SiO/4H-SiC(0001) interface are oxidized. Carbon clusters are formed in the interface layer. Oxygen molecules react with the carbon clusters and formed CO molecules.
C in dry oxygen ambient on silicon carbide and their thermal annealing effectsYoshikawa, Masahito; Ishida, Yuki*; Jikimoto, Tamotsu*; Hijikata, Yasuto*; Ito, Hisayoshi; Okumura, Hajime*; Takahashi, Tetsuo*; Tsuchida, Hidekazu*; Yoshida, Sadafumi*
Denshi Joho Tsushin Gakkai Rombunshi, C, 86(4), p.426 - 433, 2003/04
no abstracts in English
Fumizawa, Motoo; Kameda, Atsuyuki*; Nakagawa, Takashi*; Wu, W.*; Yoshikawa, Hidekazu*
Nuclear Technology, 141(1), p.78 - 87, 2003/01
Times Cited Count：5 Percentile：36.81(Nuclear Science & Technology)no abstracts in English
interfaces by optical and electrical measurementsIshida, Yuki*; Takahashi, Tetsuo*; Okumura, Hajime*; Jikimoto, Tamotsu*; Tsuchida, Hidekazu*; Yoshikawa, Masahito; Tomioka, Yuichi*; Midorikawa, Masahiko*; Hijikata, Yasuto*; Yoshida, Sadafumi*
Materials Science Forum, 389-393, p.1013 - 1016, 2002/00
Times Cited Count：4 Percentile：20.33(Materials Science, Multidisciplinary)no abstracts in English
Fukunaga, Sakae*; Yoshikawa, Hideki; Fujiki, K.*; Asano, Hidekazu*
Materials Research Society Symposium Proceedings, Vol.353, p.173 - 180, 1995/00
None
Mano, Tadashi; Yoshikawa, Hideki; Fukunaga, Sakae*; Yui, Mikazu; Yamagata, Junji*; Asano, Hidekazu*; Yamanaka, Yumiko*
PNC TN8410 94-117, 60 Pages, 1993/03
None
Yoshikawa, Hideki; Yui, Mikazu; Sasaki, Noriaki; Fukunaga, Sakae*; Asano, Hidekazu*; *
PNC TN8410 92-013, 232 Pages, 1992/01
Geomicrobiology for the geological disposal of radioactive wastes and the assessment of potential microbial effects on chemical and physical changes in repository environments and nuclide transport have been pointed out to be of cardinal importance. However, the detailed effects of microbes are poorly understood. In order to study microbial activities in underground and their effects on a repository and to know the recent study status, a literature survey was performed. In addition to this, the current research activities of major research laboratories in the world were investigated. And microbiology related meetings and conferences were also searched. In the literature survey, biodegradation and physical disruption of materials, gas generation, alteration of ground-water chemistry and the direct uptake of radionuclides were identified as factors which potentially affect the nuclide containment capability of the repository. And through the search for laboratories and meetings, information on the most recent status of biological study on the underground repository and on conferences related to geomicrobiology were obtained, respectively.
interface by the first-principles molecular dynamics simulationMiyashita, Atsumi; Onuma, Toshiharu*; Yoshikawa, Masahito; Iwasawa, Misako*; Nakamura, Tomonori*; Tsuchida, Hidekazu*
no journal, ,
Silicon carbide (SiC) semiconductor devices are expected to be used under severe environments such as outer space and/or nuclear power plants. However, at this time, SiC devices don't present the predictable performance, since defects at interface reduce electric characteristics of them. The relation among atomic structures, interfacial defects and electric characteristics is not clear. Therefore, we tried to solve these problems by the computer simulation. The SiO/SiC interface structure is generated and the electronic geometry is decided by the first-principle molecular dynamics (MD) simulation with the Earth-Simulator. The amorphous interface structure is made by heating and rapid quench calculation using 444 atoms model. The heating temperature is 4000K, the heating time is 3.0ps, and the speed of rapid quench is 
. After a rapid quench, the atomic structure became an almost perfect interfacial structure. However, a few defect energy levels were still observed in the band gap. The defect energy levels are originated from the localized electronic distribution of the interfacial oxygen.
thin films deposited on 4H-SiC(0001) substrates by capacitance-voltage methodYoshikawa, Masahito; Nakamura, Tomonori*; Miyashita, Atsumi; Onuma, Toshiharu*; Tsuchida, Hidekazu*
no journal, ,
no abstracts in English
/SiC interface structure by the first-principlesMiyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Yoshikawa, Masahito; Tsuchida, Hidekazu*
no journal, ,
no abstracts in English
Ishii, Hirotake*; Bian, Z.*; Sekiyama, Tomoki*; Shimoda, Hiroshi*; Yoshikawa, Hidekazu*; Izumi, Masanori; Kanehira, Yoshiki; Morishita, Yoshitsugu
no journal, ,
This study is to development of line-marker and hybrid tracking technology including Multi camera and gyro sensor. Evaluation experiment for new tracking technology is conducted in Nuclear power plant.
/4H-SiC(0001) interface oxidation process; Formation of carbon clusterOnuma, Toshiharu*; Miyashita, Atsumi; Iwasawa, Misako*; Yoshikawa, Masahito; Tsuchida, Hidekazu*
no journal, ,
no abstracts in English
/SiC interface by the simulation; First-principles molecular dynamicsMiyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Tsuchida, Hidekazu*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
Miyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Tsuchida, Hidekazu*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
/SiC interface structure by the first-principles, 2Miyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Tsuchida, Hidekazu*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
/4H-SiC(0001) interfaceOnuma, Toshiharu*; Miyashita, Atsumi; Iwasawa, Misako*; Yoshikawa, Masahito; Tsuchida, Hidekazu*
no journal, ,
no abstracts in English
Miyashita, Atsumi; Onuma, Toshiharu*; Iwasawa, Misako*; Tsuchida, Hidekazu*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
