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Exciton dephasing via phonon interactions in InAs quantum dots: dependence on quantum confinement

Borri, Paola ORCID:, Langbein, Wolfgang Werner ORCID:, Woggon, U., Stavarache, V., Reuter, D. and Wieck, A. D. 2005. Exciton dephasing via phonon interactions in InAs quantum dots: dependence on quantum confinement. Physical Review B: Condensed Matter and Materials Physics 71 (11) , 115328. 10.1103/PhysRevB.71.115328

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We report systematic measurements of the dephasing of the excitonic ground-state transition in a series of InGaAs?GaAs quantum dots having different quantum confinement potentials. Using a highly sensitive four-wave mixing technique, we measure the polarization decay in the temperature range from 5 to 120 K on nine samples having the energy distance from the dot ground-state transition to the wetting layer continuum (confinement energy) tuned from 332 to 69 meV by thermal annealing. The width and the weight of the zero-phonon line in the homogeneous line shape are inferred from the measured polarization decay and are discussed within the framework of recent theoretical models of the exciton-acoustic phonon interaction in quantum dots. The weight of the zero-phonon line is found to decrease with increasing lattice temperature and confinement energy, consistently with theoretical predictions by the independent Boson model. The temperature-dependent width of the zero-phonon line is well reproduced by a thermally activated behavior having two constant activation energies of 6 and 28 meV, independent of confinement energy. Only the coefficient to the 6-meV activation energy shows a systematic increase with increasing confinement energy. These findings rule out that the process of one-phonon absorption from the excitonic ground state into higher energy states is the underlying dephasing mechanism.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Physics and Astronomy
Subjects: Q Science > QC Physics
Publisher: American Physical Society
ISSN: 1098-0121
Last Modified: 01 Dec 2022 10:15

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