2001 Fiscal Year Final Research Report Summary
Fano resonance of low-dimensional excitons
| Project/Area Number |
11640308
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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 | University of Tsukuba |
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Principal Investigator |
HINO Kenichi University of Usukuba, Institute of Materials Science, Associate Professor, 物質工学系, 助教授 (90228742)
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| Project Period (FY) |
1999 – 2001
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| Keywords | exciton / low-demensinal semi conductor / Fano resonace / quantum well / superlattices / Wannier-Stark ladder / valence-band mixing / multi-channel scattering |
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| Research Abstract |
Fano resonance (FR) of low-dimensional excitons manifests itself due to couplings of subbands generated by spatial quantum confinement. The resulting FR states belong to multi-channel scattering (MCS) states. However, there were a lot of difficulties in conventional theoretical methods because of little account of MCS problems. In the present study, one has succeeded to overcome all of these problems and to establish a novel MCS theory of low-dimensional excitons, which enables us to evaluate natural spectra and resonance widths of FR in ab initio manner. This approach consists of the adiabatic expansion and the R-matrix propagation based on the Luttinger Hamiltonian incorporating the effect of valence-band mixing (VBM). This theory has been applied to a single quantum-well (QW) and superlattices (Wannier Stark ladder (WSL)) of GaAs/Al_xGa_<1-x>As semiconductors, and variance of FR spectra due to changes of well-thickness and strength of electric- and magnetic-fields is examined in de tail. Above all, the following new findings are obtained. In relatively wide QW's, overlap resonance of FR ascribable to VBM is substantial. In an asymmetric double QW's, a hy bridized exciton states generated by an electron and hole pair pertaining to different wells has a somehow pronounced oscillator strength, which is also discernible in the existing experiment. Furthermore, FR plays decisive roles in dimensionality transition of WSL from a quasi-two dimensional system to a bulk one with decreasing an applied electric field.
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