| Project/Area Number |
11650020
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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 | KYUSHU INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
FUJIWARA Kenzo Kyushu Institute of Technology, Dept.of Electrical Engineering, Professor, 工学部・電気工学科, 教授 (90243980)
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| Co-Investigator(Kenkyū-buntansha) |
SATAKE Akihiro Kyushu Institute of Technology, Dept.of Electrical Engineering, Assistant, 工学部・電気工学科, 助手 (90325572)
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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 |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | quantum well / photoluminescence / exciton / quantum capture / time-resolved emission / emission dynamics / radiative recombination lifetime / GaAs |
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| Research Abstract |
In order to pursue mechanisms behind the competitive quantum capture processes of photogenerated carriers as a function of lattice temperature in electronically isolated semiconductor quantum wells with different well thicknesses, photoluminescence (PL) emission dynamics have been investigated and following results are obtained.
1. Existence of quantum capture processes in PL emission spectra
Picosecond time-resolved PL experiments have been undertaken in quantum well samples consisting of three or four different size wells. It is experimentally found that the lower energy emission bands show much weaker PL intensities than the higher energy ones, as opposed to the PL intensity distribution expected in thermal equilibrium conditions. The unique PL characteristics observed in several samples reflect the quantum capture processes and the dynamics exhibit, for example, much shorter PL lifetimes than the radiative recombination lifetimes.
2. Temperature effects on quantum capture dynamics
It i
… More
s experimentally demonstrated that the PL recombination dynamics originating from the observed competitive capture of photoexcited carriers between the quantum wells exhibit totally different temperature effects from the ones already known for the radiative recombination lifetimes of two dimensional excitons.
3. Dependence of well width fluctuations on quantum capture dynamics
Quantum capture dynamics have been studied in composite GaAs quantum wells with monolayer growth island terraces, prepared by growth-interrupted molecular beam epitaxy. From detailed analysis of the PL results, it is newly discovered that the PL intensity distribution as well as the dynamics are both significantly influenced by relative energy positions of the first excited subband state to the barrier band edge. In addition, the transfer proceeses of excitons are confirmed between the island terraces.
4. Mechanisms of quantum capture dynamics in composite quantum well systems
From comparison between two similar composite quantum well samples but with different configurations of outer clad layers (AlGaAs alloy and GaAs/AlAs superlattice digital alloy), it is found that both the PL intensity distribution and the dynamics including the temperature dependence are very different each other. These results suggest that mechanisms behind the quantum capture processes are sensitive to the subband energy structures of the clad layers, from which photogenerated carriers are distributed to the different wells with different subband energy structures. Less
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