| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Kazuyuki TOHOKU UNIVERSITY,GRADUATE SCHOOL OF SCIENCE,RESEARCH PHYSICIST, 大学院・理学研究科, 助手 (70261542)
UCHIDA Wakio TOHOKU UNIVERSITY,GRADUATE SCHOOL OF SCIENCE,PROFESSOR, 大学院・理学研究科, 教授 (50005790)
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| Research Abstract |
(1) We have investigated the structures, vibrational excitation spectra, valence band spectra and C is core level spectra of C60 molecules adsorbed on Si(111)7x7 and Si(100)2x1 surfaces, using a combined measurement of high-resolution electron-energy-loss spectroscopy (HREELS) and scanning tunneling microscopy (STM), HREELS-STM, and a photoelectron spectroscopy (PES). At a coverage between 1 ML and 0.25 ML, HREELS and PES measurements show that the interaction is as weak as the van der Waals interaction on both surfaces. At a coverage lower than 0.25 ML, some contradictory results are obtained by HREELS and PES.With HREELS, the softening of several vibrational modes is observed on the Si(111)7x7 surface, but no indication of softening is observed on the Si(100)2x1 surface. The charge transfer scheme explains the softening well. These results by HIREELS indicate that the nature of the bonding is ionic on the Si(111)7x7 surface and of the van der Waals type on the Si(100)2x1 surface. On the contrary, the bonding states between C60 molecules and Si substrates are clearly observed at 2.4 eV on both surfaces with PES.The PES measurements indicate that the interaction has a covalent character at the Si(111)7x7 surface, and that the nature is in between covalent and ionic characters, i.e. not pure ionic or covalent limit, at the Si(100)2x1 surface. We have discussed the nature of the interaction manifested by PES and HREELS-STM measurements in comparison with the spectra of C60 molecules adsorbed on metal surfaces.
(2) We have also investigated the initial growth of silicon carbide film by C60 precursor.
(3) We have discussed the applicability and possibility of a combined measurement system of HREELS-STM.
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