| Project/Area Number |
10650001
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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 |
Applied materials science/Crystal engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAITO Toshio University of Tokyo, CCR, Research Associate, 国際・産学共同研究センター, 助手 (90170513)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKAWA Yasuhiko University of Tokyo, RCAST, Professor, 先端科学技術研究センター, 教授 (30134638)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | nitride semiconductors / gallium nitride / indium gallium nitride / quantum dot / electronic structure / tight-binding method / valence-force-field method / quantum confinement / 窒化インジウム / 混晶 / 量子閉じ込め効果 |
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| Research Abstract |
The atomic and electronic structures of InィイD2xィエD2GaィイD21-xィエD2N hexagonal quantum dots (QDs) have been calculated theoretically. A valence-force-field method is used for the calculation of the atomic positions and strain energy in the InィイD2xィエD2GaィイD21-xィエD2N random alloy. We analyzed the bond-length and bond-angle distribution in the alloy due to the "alloy disorder." The calculated change in the average Ga-N and In-N bond lengths vs. x is in good agreement with the recent experimental data. The alloy phase stability is studied based on the calculated strain energy. An spィイD13ィエD1 tight-binding method is used for the calculation of the electronic structure of the free-standing and GaAs-embedded QDs. The energy gap, energy levels, and wavefunctions are calculated accurately as a function of the QD size. For the InィイD20.2ィエD2GaィイD20.8ィエD2N QD embedded in the GaN barrier (dot diameter 86.4 Å, dot height 20.8 Å, GaN barrier thickness 21 Å), we calculated the energies of electron and hole levels (C1-C3 and V1-V3, respectively) near the energy gap. We found that the three hole levels (V1-V3) are closely spaced, while the electron levels are the ground state (C1) and the closely spaced excited states (C2 and C3). The gap value EィイD2gィエD2(C1-V1) is calculated to be 2.715 eV. The electron wavefunction is almost completely confined in the QD inside, while exhibiting atomic scale fluctuation due the "alloy disorder."
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