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Direct Creation of Excitonic Molecules by Two‐Photon Absorption in Quantum Wells
Author(s) -
Hassan A. R.
Publication year - 1994
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221810123
Subject(s) - biexciton , quantum well , fine structure , exciton , photon , absorption (acoustics) , two photon absorption , quantum dot , physics , condensed matter physics , atomic physics , molecular physics , chemistry , quantum mechanics , optics , laser
A theory of the direct creation of excitonic molecules (biexcitons) by direct two‐photon absorption in semiconductor quantum well structures is developed. An analytical expression of the biexciton two‐photon absorption coefficient is given for both photon polarizations. Excitonic‐, interband‐two‐photon, and exciton one‐photon processes in quantum wells (QW) are also investigated. The analytical forms and numerical values of the momentum matrix elements involved in each process are provided. The biexciton matrix element is calculated adopting a six‐parameter variational wave function. A numerical estimation for GaAs QW shows that the biexciton two‐photon absorption (BTPA) process dominates the other processes by different orders of magnitude. This enhancement essentially comes from the resonance effect and the structure of the matrix elements included in each process. Furthermore, the BTPA process in the QW for both polarizations is enhanced over its bulk value by about four and five orders of magnitude. This increase is interpreted as due to the spatial confinement of the QW.