| Project/Area Number |
08640412
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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 Tokyo |
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Principal Investigator |
ANDO Tsuneya Univ.of Tokyo, Inst.for Solid State Phys., Professor, 物性研究所, 教授 (90011725)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | carbon nanotube / graphite / Aharonov-Bohm effect / heterostructure / Boltzmann transport / Topology / コンダクタンスゆらぎ / 局在効果 / ボツルマン輸送方程式 / カーボン・ナノチューブ / 半導体ヘテロ構造 / トポロジー効果 |
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| Research Abstract |
A carbon nanotube consists of coaxially rolled graphite sheets. Because the distance between different sheets is much larger than the nearest neighbor carbon atoms, electronic properties are dominated by those of a single-shell nanotube. A single-shell CN can be either a metal or a semiconductor depending on the circumference length and the helical fashion. The purpose of this project is to study effects of the topological structure of nanotubes on their transport properties.
Various calculations have been performed to predict energy bands of nanotubes. It has been found that the characteristic properties are all reproduced quite well in a k・p method, which is effective in the study of effects of external fields such as a magnetic and electric field. In fact, it has been successful in the study of magnetic properties including the Aharonov-Bohm effect on the band gap, optical absorption spectra, and lattice instabilities in the presence and absence of a magnetic field.
Transport properties are interesting because CN's have a structure topologically different from that of conventional quantum wires fabricated using semiconductor heterostructures. There have been some reports on experimental study of transport in CN bundles. Quite recently, measurements of magnetotransport of a single nanotube became possible.
During the period of two-year project, the conductivity of CN's was calculated using the Boltzmann transport equation and in Landauer' approach for a model of short-range scatterers. The study was made on transport across a junction of nanotubes having difference circumferences and on exciton effects in optical absorption spectra of semiconducting nanotubes and metallic nanotubes in the presence of an Aharonov-Bohm magnetic flux.
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