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Quantum beats between trion and exciton transitions in modulation-doped CdTe quantum wells

1999; American Physical Society; Volume: 60; Issue: 8 Linguagem: Inglês

10.1103/physrevb.60.5797

1095-3795

P. Gilliot, D. Brinkmann, J. Kudrna, O. Crégut, R. Lévy, Alexandre Arnoult, J. Cibért, S. Tatarenko,

Near-Field Optical Microscopy

We investigate the coherence properties of trions (charged excitons) and neutral excitons in modulation p-doped $\mathrm{CdTe}/\mathrm{Cd}\mathrm{Mg}\mathrm{ZnTe}$ quantum wells by means of femtosecond four-wave-mixing (FWM) experiments. Under simultaneous and coherent excitation of the exciton and trion resonances, we observe a modulation of the FWM traces due to quantum beats. This excludes a complete spatial separation of trions and neutral excitons. A minor contribution from polarization interferences is explained by the superposition of signals from localized trions and free excitons.