OPTICAL DEPHASING IN SEMICONDUCTOR MIXED-CRYSTALS

TitleOPTICAL DEPHASING IN SEMICONDUCTOR MIXED-CRYSTALS
Publication TypeJournal Article
Year of Publication1992
AuthorsSIEGNER, U., D. WEBER, E. O. GOBEL, D. BENNHARDT, V. HEUCKEROTH, R. Saleh, S. D. BARANOVSKII, P. THOMAS, H. SCHWAB, C. KLINGSHIRN, J. M. HVAM, and V. G. LYSSENKO
JournalPhysical Review B
Volume46
Pagination4564-4581
Date PublishedAUG 15
Type of ArticleArticle
ISSN0163-1829
Abstract

The influence of disorder and localization on optical dephasing of excitons in the semiconductor mixed crystals CdS1-xSex and AlxGa1-xAs has been investigated by means of time-resolved four-wave mixing and photon echo experiments. A dephasing time of several hundreds of picoseconds is found for resonantly excited localized excitons in CdS1-xSex while the dephasing time in AlxGa1-xAs amounts to only a few picoseconds. In CdS1-xSex dephasing results mainly from hopping processes, i.e., exciton-phonon interaction. The contribution of disorder is negligible in terms of phase relaxation in CdS1-xSex. In contrast, in AlxGa1-xAs elastic disorder scattering yields an essential contribution to the dephasing rate. We present a theoretical model, which treats dephasing of optical excitations in a disordered semiconductor, including the influence of disorder as well as exciton-phonon interaction. On the base of this model, the experimentally observed differences in the dephasing behavior of excitons in CdS1-xSex and AlxGa1-xAs are related to the microscopic structure of the disorder potential and the mechanism of exciton localization.

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