| Project/Area Number |
14540291
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SUZUKI Shugo University of Tsukuba, Institute of Materials Science, Associate Professor, 物質工学系, 助教授 (90241794)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAO Kenji University of Tsukuba, Institute of Materials Science, Professor, 物質工学系, 教授 (30011597)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Field Effect Doping / Molecular Crystal / Superconductivity / First-Principles Calculation / Density Functional Theory / Band Structure / Density of States / Electron Distribution / C_<60>単層膜 / 2次元エバルト和 / ホールドープ |
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| Research Abstract |
Field effect doping is expected to be a good method for introducing carriers into crystals with respect to several points. In the present study, we study theoretically the characteristics of the geometries and electronic structure of molecular crystals where carriers are introduced by field effect doping. The calculations are performed by using first-principles method based on the density functional theory. In particular, to treat the two dimensional systems realistically, we employ the two dimensional Ewald method for calculating electrostatic potential originated in the long range Coulomb interaction. We first carry out the calculations on the C60 monolayer films. As a result, when the carrier density is one electron per C60, it is found that the doped electrons are almost localized on the surface where the electric field is applied. We also study the hole-doped case and find that the doped hole is also localized on the surface where the electric field is applied. We next investigate higher doping cases where the carrier density is two to three electrons per C60. In these cases, we find that there exist remarkable splitting in the valence bands. At the same time, we also find characteristic structures in the densities of states, in accordance with the splitting in the valence bands. Similar results are obtained in the hole-doped cases. Furthermore, we calculate three layer C60 films and find that the carriers are also localized on the surface where the electric field is applied and thus confirm that the localization of carrier on the surface can actually occur independent of the thickness of the films for the carrier densities investigated in the present study.
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