2002 Fiscal Year Final Research Report Summary
IN-PLANE ELECTRON TRANSPORT AND MANY BODY EFFECT IN HIGH DENSITY SELF-ASSEMBLED QUANTUM DOT SYSTEMS
| Project/Area Number |
13650359
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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 |
Electronic materials/Electric materials
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| Research Institution | KONAN UNIVERSITY |
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Principal Investigator |
SUGIMURA Akira KONAN UNIV., FAC. SCIENCE & TECHNOLOGY, PROFESSOR, 理工学部, 教授 (30278791)
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| Co-Investigator(Kenkyū-buntansha) |
ANDO Hiroaki KONAN UNIV., FAC. SCIENCE & TECHNOLOGY, PROFESSOR, 理工学部, 教授 (50330402)
INADA Mitsuru HIGH-TECH RESEARCH CENTER, POST DOC. RESEARCHER, 理工学部, 教授 (00330407)
UMEZU Ikurou KONAN UNIV., FAC. SCIENCE & TECHNOLOGY, ASSISTANT PROFESSOR, 理工学部, 助教授 (30203582)
パフロ バッカロ ATR環境適応通信研究所, 研究員
VACCARO Pablo ATR ADAPTIVE COMMUNICATION LABS., RESEARCHER
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| Project Period (FY) |
2001 – 2002
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| Keywords | quantum dot / self assemble / electron transport / inter-dot coupling / photo conductance / many body effect / g factor / gate |
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| Research Abstract |
Purpose of the present project is to explore the quantum dot structure, in which electron-electron interaction is strong enough to manifest strong nonlinearity in current-voltage characteristics. Specifically in-plane electron transport properties for self-assembled InAs/GaAs quantum dot system with high dot density were extensively studied. We investigated the photo-conductive properties for the high-density quantum dot systems and observed resonance peaks. In order to clarify the origin of the resonance, we measured the photo-conductivity applying magnetic field, and we again observed the resonance peaks as a function of the applied voltage for the high dot density samples. Dependence of the measured resonance voltage on the strength of the magnetic field provides us the information on the effective g factor. Thus obtained g factor value turned out to be much smaller than that of the bulk InAs. Analysis of this result indicates that the resonance peak is originated from the current which passed through quantum dots. Since photo-conductive phenomenon includes two carriers, electron-electron interaction effect is not easy to be observed. We thus tried to establish the unipole device structure, where only electrons works as a carrier, by attaching the gate to control the electron number. However, no clear nonlinearity was observed, although various kinds of FET structures were tried. The reason for this result is basically that the registivity of the quantum dot layer is so high that the inter-dot tunneling current is much weaker than the parallel leak current. As another candidate for the coupled quantum dot systems, we studied CdS quantum dot system covered with polymer chains. We observed results which indicate that the electrons on different dots actually couples to each other. This system is considered to be another promising structure for the nonlinear devices.
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