| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Tetsuya Univ.of Tokyo, Dept.of Superconductivity, Associate Professor, 大学院・工学系研究科, 助教授 (10189532)
TOMITORI Masahiko Japan Advance Institute of Science and Technology, Hokuriku, School of Materials, 材料科学研究科, 助教授 (10188790)
SHIGEKAWA Hidemi Univ.of Tsukuba, Institute of Materials Science, Associate Professor, 物質工学系, 助教授 (20134489)
OGAWA Keiichi Yokohama City Univ.Graduate School of Integrated Science, Professor, 大学院・総合理学研究科, 教授 (00233411)
IWASAWA Yasuhiro Univ.of Tokyo, Dept.of Chemistry, Professor, 大学院・理学系研究科, 教授 (40018015)
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| Research Abstract |
In this group, the tunnel characteristics of various surfaces were studied by scanning tunneling microscopy/spectroscopy (STM/STS) with atomic resolution. These studies cover, for example, the structures of reconstructed surfaces of metals and semiconductors, the atomic and molecular processes of adsorption or thin film growth, the phase transition of two-dimensional phases on surfaces, and catalytic processes. The results achieved in these studies are briefly summarized as follows.
The adsorption processes, structure and electronic properties of metal-adsorbed Si (001), (111), and (113) surfaces were studied. In the case of Ga/Si (001), it was concluded that Ga dimers are adsorbed parallel to the Si dimer rows of the substrate based on LEED and STM/STS results (A.Kawazu). Atomically resolved STM topography of the TiO_2 (rutile) (110) surface was observed for the first time. Metal adatoms (Na, Ni) and adsorbed molecules (carboxylic acids, pyridine derivatives, CO_2) on this surface were
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also individually resolved. The migration and reaction of adsorbed molecules were also successfully visualized in-situ, even at elevated temperatures (Y.Iwasawa). Three issues, 1) radiation damage introduced by Ar ion bombardments onto Si (111) -7*7 and the cleaved surface of MoS_2,2) nucleation and growth processes of a triangular 7*7 domain on quenched Si (111) -1*1 and 3) direct observation of the Cu-O sigma bond in Bi-based high Tc superconductors were studied (K.Ogaswa). *@ An atomically resolved structural change between C (2x2) and P (2x2) *@ arrangements of the Si (100) surface was studied at 6K.The observed change was due to the fluctuation of a new type of phase defects on dimer rows. Dimer flip-flop motion at the phase boundary, and creation and annihilation of the antiphase domain were clearly observed (H.Shigekawa). By using a build-up tip made from a[111]-oriented W filament which can be repeatedly sharpened and easily cleaned by applyng a high voltage, reproducible tunneling spectra were successively obtained on Si (111) 7*7 surface (M.Tomitori). An ultrahigh-vacuum low-temperature STM/STS instrument, which can be stably operated in a wide temperature range under intense magnetic fields, has been developed. This has been applied in the investigation of layred materials including high Tc superconductors and transition metal dichalcogenide (T.Hasagawa). Less
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