| Project/Area Number |
09450128
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
KAWAKAMI Yoichi Kyoto University, Department of Electronic Science and Engineering, Associate Professor, 工学研究科, 助教授 (30214604)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Shigeo Kyoto University, Department of Electronic Science and Engineering, Professro, 工学研究科, 教授 (30026231)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥6,500,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1997: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | Wide-bandgap Semiconductors / Exciton / Exciton Molecule / Low-dimensional Structures / Localization / Time-resolved Spectroscopy / PL-dynamics / Laser Diode / 顕微分光 / 巨大振動子効果 / レーザ |
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| Research Abstract |
The objective of this project is (i) fabrication of low-dimensional structures of both ZnSe-based II-VI and GaN-based III-V wide-bandgap semiconductors, (ii) assessment of fundamental excitonic properties in such structures, and (iii) study of key points for the realization light emitting diodes (LEDs) with high quantum efficiency, laser diodes (LDs) with low threshold and photonic devices with high switching speed utilizing large oscillator strength of excitonic system. The results obtained in the period of 1997 to 1998 can be summarized as follows.
(1) Self-organized CdSe/ZnSe quantum dots (QDs) were fabricated on the cleavage-induced GaAs (110) surface in ultra high vacuum by molecular beam epitaxy (MBE). CdSe layers showed the Stranski-Krastanow growth mode. By using the microscopic PL spectroscopy, the broad PL peak of QD's was resolved into a lot of sharp peaks, indicating that the fabricated CdSe islands have quasi-zero-dimensional delta-function like density of states.
(2) CdSe (1, 2, 3ML) single quantum wells (SQWs) / ZnSe waveguides (50nm in each) / ZnSSe (0.85 mum in each) / GaAs buffers were coherently grown on GaAs (100) substrates by means of two-chamber MBE technique. Dynamical behavior of localized excitons in such structures was assessed using time-resolved photoluminescence spectroscopy. It was found that radiative recombination of localized bi-excitons contributes to the optical gain in the structure with 1 ML SQW at low-temperature.
(3) Dimesionality of excitons was investigated in InGaN-quantum-well devices with various In compositions. It was found that the radiative recombination times of blue LEDs were almost independent on temperature (4-5ns) suggesting that the emission centers can be attributed to zero-dimensional nature.
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