| Project/Area Number |
11215208
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Osaka City University |
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Principal Investigator |
KARASAWA Tsutomu Graduate School of Science, Osaka City University, Professor, 理学研究科, 教授 (90106336)
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| Co-Investigator(Kenkyū-buntansha) |
IIDA Takeshi Graduate School of Science, Osaka City University, Professor, 理学研究科, 教授 (80047191)
NAKAYAMA Masaaki Graduate School of Engineering, Osaka City University, Professor, 工学研究科, 教授 (30172480)
AKAI Ichiro Graduate School of Science, Osaka City University, Assistant Professor, 理学研究科, 助教授 (20212392)
SUZUKI Masato Graduate School of Science, Osaka City University, Lecturer, 理学研究科, 講師 (70254381)
MIZOGUCHI Kouji Graduate School of Engineering, Osaka City University, Assistant Professor, 工学研究科, 助教授 (10202342)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥51,200,000 (Direct Cost: ¥51,200,000)
Fiscal Year 2001: ¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1999: ¥40,700,000 (Direct Cost: ¥40,700,000)
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| Keywords | high-density excitons / BiI_3 staccking fault exciotns / layered crystals (GaSe, PbI_2) / exciton superfluidity / GaAs / AlAs super lattices / type-II super lattice and quantum wells / Bose-Einstein statistics / macroscopic quantum phenomena on excitons / GaSe / 励起子のポーズ凝縮 / 励起子の超流動 / 光誘起相転移 / Gase |
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| Research Abstract |
In our research, photoinduced high-density effects on excitons and phonons, and their coherent propagation at quasi tow-dimensional interfaces in semiconductors have been studied from experimental and theoretical aspects.
In layered crystals BiI_3, GaSe, and PbI_2, we have studied spatial and temporal behavior of high-density exciton masses and their nonlinear optical responses. In BiI_3, extraordinarily large spatial expansion of the excitons confined in a tow-dimensional stacking fault interface (SFE) was observed in the space- and time-resolved photoluminescence above a threshold excitation density. The degenerate four-wave-mixing (DFWM) light induced by spatially isolated two laser-light spots tuned to the SFE state on the sample surface was emitted owing to the coherent transport of the exciton mass from one to the other exciting spot sites showing the SFE-polariton masses being in a Bose-condensed phase. In GaSe as well as PbI_2, it turned out that heavy photo-excitation brings ab
… More
out recoil luminescence due to scattering with the other excitons or carriers in competition with the biexciton formation.
For the excitonic properties and coherent-phonon phenomena in superlattices (SLs), we have obtained the following results. (1) In GaAs/AlAs type-II SLs, where the electron and hole are spatially separated in the AlAs and GaAs layers respectively, the density relation of the excition-biexciton system in the decay process is dominated by Bose-Einstein statistics, which results in a threshold-like increase in the biexciton density. (2) In GaAs/AlAs type-I SLs, the transformation process from the biexciton to the electron-hole-plasma phase is revealed, connecting with the band-gap renormalization due to high-density carriers. (3) In InAs/GaAs SLs, the photoexcited plasmon couples with the GaAs-like coherent-LO phonon through the miniband state.
We have theoretically studied macroscopic quantum phenomena in an interacting dilute quasi-two-dimensional Bose gas of excitons in a type-II semiconductor quantum wells and clarified its ordered states, elementary excitations and mechaisms of phase transitions. Less
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