Femtosecond relaxation dynamics of excitons localized by disorder in semiconductors
| Project/Area Number |
63460021
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Hokkaido University |
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Principal Investigator |
MINAMI Fujio Hokkaido University, Research Institute of Applied Electricty, Associate Professor, 応用電気研究所, 助教授 (30200083)
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| Co-Investigator(Kenkyū-buntansha) |
ASAKA Shuji Hokkaido University, Research Institute of Applied Electricity, Instructor, 応用電気研究所, 助手 (00167876)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1988: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Keywords | Femtosecond Spectroscopy / Localized exciton / Phase relaxation / Diamond anvil cell / GaAs / AlAs superlattices / Temporally Incoherent light / Layered compound / スェムト秒分光 / ダイヤモンドアンヴィル / GaAs@AlAs超格子 / インコヒーレントパルス分光 / GaAs |
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| Research Abstract |
1) We made a passively mode-locked dye laser system. The dye laser produces a train of 100 fs pulses at the rate of 100 MHz. The wavelength tuning range is 580-620 nm.
2) The phase relaxation time of the exciton in GaSe was measured by using temperature-dependent photon echo method. It is found that the optical dephasing is caused by phonon scattering above 30 K.
3) A close correlation was found between the radiative lifetime and the phase correlation time of the free excitons in GaSe. This result gives a direct experimental proof of the recent theoretical prediction.
4) We made two different hole burning experiments in the free exciton line in GaSe: pulse propagation delay and pump-probe experiments. Both results support arguments for partial exciton localization by stacking disorder.
5) We proposed two new methods to investigate femtosecond processes: pump-probe and upconversion methods using temporally incoherent lights.
6) Temporal behavior of hot carriers in CdSe was investigated with subpicosecond accuracy, by using a novel pump-probe technique. in which the self-phase modulation effect in an optical fiber is utilized to extend the spectral width of the probe pulse. Pump-induced changes is explained by the formation of an electron-hole plasma and a succeeding thermal relaxation of the plasma.
7) Photoluminescence spectra of short-period GaAs/AlAs superlattices were studied as a function of hydrostatic and uniaxial pressure at 20 K. It is found that lowest excited state is an indirect exciotns at Xz.
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Report
(3 results)
Research Products
(30 results)
