| Project/Area Number |
11650008
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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 | Tohoku University (2000)
The University of Tokyo (1999) |
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Principal Investigator |
USAMI Noritaka Institute for Materials Research, Tohoku University, Associate Professor, 金属材料研究所, 助教授 (20262107)
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| Co-Investigator(Kenkyū-buntansha) |
UJIHARA Toru Institute for Materials Research, Tohoku University, Research Associate, 金属材料研究所, 助手 (60312641)
SAZAKI Gen Institute for Materials Research, Tohoku University, Research Associate, 金属材料研究所, 助手 (60261509)
NAKAJIMA Kazuo Institute for Materials Research, Tohoku University, Professor, 金属材料研究所, 教授 (80311554)
SHIRAKI Yasuhiro The University of Tokyo, Research Center for Advanced Science and Technology, Professor, 先端科学技術研究センター, 教授 (00206286)
長田 俊人 東京大学, 物性研究所, 助教授 (00192526)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | microscopic photoluminescence / semiconductor quantum dot / semiconductor quantum well / modulation doping / charged exciton / electron localization / indirect semiconductor / フォトルミネッセンス / 局在励起子 / 励起子分子 |
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| Research Abstract |
In this project, we have tried to establish spectroscopic technique to evaluate microscopic interface roughness, and to characterize inherent optical properties of quantum structures without being affected by structural fluctuations. As a technique, we exploited to combine local probe spectroscopy to use objective lens for microscope and lithography technique to fabricate small window on top of the sample, leading to improved spatial resolution.
We selected quantum structures made from compound semiconductors, which are studied to improve electrical and optical device performance. By reducing the feature sizes such as quantum wires and quantum dots, the impact of the size fluctuations on the properties becomes significant. This explains why we selected the quantum structures.
We found that localized excitons trapped by some microscopic potential fluctuations in InGaAs/GaAs quantum wells, which are not detected by macroscopic photoluminescence, can be detected by our technique. By measuring growth teroperature dependence, we clarified that the increase of the growth temperature lead to the deterioration of the interface abruptness due to the In surface segregations, however, the interface roughness is improved compared to the sample grown at lower temperatures. In addition, we succeeded in observing charged excitons in quantum dots and controlling the charged states by applying electric field to modulation-doped quantum dots.
Furthermore, we tried to create novel quantum structures to insert ultra thin film as a localized center for electrons, and succeeded in improving drastically improve the luminescence efficiency of indirect semiconductors, and we found that stacking of quantum dots greatly modify the growth mode. As a next step, we will apply our spectroscopic technique to these quantum structures and clarify their microscopic structures and mechanisms for improved luminescence efficiency.
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