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HL: Halbleiterphysik

HL 49: Poster II

HL 49.51: Poster

Donnerstag, 27. März 2003, 16:30–19:00, HSZ/P2

Speckle Averaged Spectral Interferometry of Rayleigh Scattering in Single and Multiple Quantum Wells — •W. Langbein and G. Kocherscheidt — Experimentelle Physik IIb, Universität Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund

Spectral interferometry (SI) of the resonant secondary emission (RSE) of the fundamental heavy-hole transition in GaAs quantum wells measures the coherent RSE called Resonant Rayleigh scattering (RRS). The RRS dynamics is given by the time-evolution of the excited exciton wave-packet, which depends on the exciton level statistics. Compared to a spatially uncorrelated level statistics, the exciton eigenstates show a spatial correlation [1] by (i) level-repulsion, i. e. a reduction in the probability of finding states close in energy and space (ii) a spatial correlation of the disorder potential. The SE dynamics of multiple quantum wells measured by up-conversion was interpreted in these terms. However, similar oscillations were observed by speckle analysis in the RRS of MQWs, while they were absent for SQWs. The oscillations were thus attributed to radiative coupling between the wells.[2] In the present work we measured the RRS intensity of SQWs and MQWs of various thicknesses by SI for many (>1000) speckles. Compared to the dynamics for uncorrelated level statistics, the SQWs show an initial RRS suppression similar to the effect of level repulsion, while the MQWs show an initial RRS enhancement, with pronounced oscillations for MQWs of small disorder.

[1] V. Savona et al. Phys. Rev. Lett. 84, 183 (2000)

[2] G. Malpuech et al. Phys. Rev. Lett. 85, 650 (2000)