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HL: Halbleiterphysik
HL 20: Quantenpunkte und -dr
ähte: Optische Eigensch. II
HL 20.6: Vortrag
Dienstag, 12. März 2002, 15:45–16:00, H14
Quantum mechanical repulsion of exciton levels in disordered quantum wells — •Tobias Guenther1, Francesca Intonti1, Valentina Emiliani1, Christoph Lienau1, Thomas Elsaesser1, Vincenzo Savona2, Erich Runge2 und Roland Zimmermann2 — 1Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin — 2Institut fuer Physik, Humboldt Universitaet, 10117 Berlin
Localized states play a key role for the optical and transport properties of disordered quantum systems, e.g., thin quantum wells. Here, exciton localization within a interface-roughness induced disorder potential gives rise to inhomogeneous broadening of far- field spectra and to narrow emission spikes from single excitons in high spatial/spectral resolution experiments. We provide clear evidence that the non-negligible spatial overlap of excitonic wavefunc-tions in adjacent minima of this disorder potential gives rise to a level-repulsion of the exci-tonic eigenenergies. This quantum-mechanical hallmark of localization is revealed through a statistical analysis of the two-energy autocorrelation function of a large set of near-field PL spectra. Through a comparison to a quantum theory of the excitonic center-of-mass motion, we demonstrate that this autocorrelation function bears precise information about the spatial correlation length of the disorder potential[1]. A comparative study of different nanostruc-tures reveals distinct growth-induced variations of the spatial and energetic correlations of excitons in disordered quantum systems. [1] F. Intonti et al., PRL 87, 076801 (2001).