From Quantum Well Exciton Polaritons to One-Dimensional Excitons
We review quantum well exciton polaritons and one-dimensional quantum confined excitons which were studied by photoluminescence spectroscopy of laterally microstructured AlxGal-xAs — GaAs quantum well systems and quantum wires as narrow as 60 nm. Freely propagating quantum well exciton polaritons were investigated in quantum well samples with microstructured cap layers. Their radiative decay was mediated by the grating coupler effect of the periodic corrugation. It is observed that also the photoluminescence spectra of wide quantum well wires are dominated by quantum well exciton polariton emission. When decreasing the wire width below L x ≈ 150 nm the polariton-specific features disappear in the spectra. Below L x = 100 nm, the concept of quasi-one-dimensional excitons is an appropriate model to describe the behavior of the observed transitions. The ID character of these excitons is manifested in the observation of several exciton resonances which are related to different energetically separated 1D quantum confined subbands, by a reduced diamagnetic shift, and by a 15% increased binding energy with respect to 2D reference samples which is particularly reflected in magneto-optical experiments.
KeywordsQuantum Well Surface Polaritons Grating Coupler Diamagnetic Shift Wire Width
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