1998 Fiscal Year Final Research Report Summary
Study on Exciton-Polariton Interaction and Biexciton Formation Mechanism in Semiconductors
| Project/Area Number |
09640394
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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 |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
HAYASHI Tetsusuke Kyoto University, Department of Fundamental Sciences, Professor, 総合人間学部, 教授 (80026799)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Masayuki Kyoto University, Department of Fundamental Sciences, Research Associate, 総合人間学部, 助手 (20240525)
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| Project Period (FY) |
1997 – 1998
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| Keywords | SEMICONDUCTOR / EXCITON / BIEXCITON / POLARITON |
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| Research Abstract |
The purpose of this research project is to investigate the role of coherent interaction and relaxation of exciton polaritons on biexciton formation, and to clarify the elementary processes of exciton interaction in semiconductors such as PbI_2 and CuCl. The main part of obtained results are as follows.
First, luminescence excitation spectra of excitonic molecules in PbI_2 have been investigated using polarized light in order to distinguish the contribution of coherent and incoherent processes on the generation of biexcitons via polariton interaction. Two-photon resonant transition of biexcitons is a coherent process of polariton interaction, and is forbidden under excitation with circularly polarized light. However, a considerable amount of biexcitons was generated by circularly polarized light at the two-photon resonant energy in PbI_2, indicating that incoherent interaction of scattered polaritons is highly effective even below the exciton resonance energy (E_T).
Next, we investigated polarization dependence of two-photon resonant transition of biexcitons in CuCl with pump-probe technique using two circularly polarized lights. In this case, the optical selection rule is found to hold exactly up to about 5 meV below E_T.
From the above results it is clarified that elastic scattering of exciton polaritons is essential for the incoherent process of biexciton formation, and its contribution depends strongly on materials.
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