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Time-resolved study of depashing mechanismen of excitons in GaAs/Al(x)Ga(1-x)As quantum-well structures

Zeitaufgelöste Untersuchung des Phasenverlust-Mechanismus von Exzitonen in GaAs/Al(x)Ga(1-x)As QW-Strukturen
: Bakker, H.J.; Leo, K.; Shah, J.; Köhler, K.


Physical Review. B 49 (1994), No.12, pp.8249-8257
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
Journal Article
Fraunhofer IAF ()
Quantentopf; quantum wells; time resolved emission spectroscopy; zeitaufgelöste Emissionsspektroskopie

We present an experimental and theoretical study of the dephasing of heavy-hole excitons in a 70 Angström GaAs/AlxGa1-xAs multiple-quantum-well structure. We measure the time-integrated threepulse four-wave-mixing signal of heavy-hole excitons in the quantum-well sample. We model the third-order nonlinear optical response incorporating the effects of a stochastic modulation of the transition frequency. We find that the dephasing of the nonlinear polarization is mainly the result of spectral-migration process of the excitons and, to a lesser extent, due to a homogeneous dephasing process. The time dependence of the four-wave-mixing signal is very well described by theory if the spectral-migration process is assumed to be energy dependent.