Abstract
We have studied wide quantum well structures with various spectroscopic tools. The effects originating from lateral quantization are found to be strongly dependent on the state under investigation and on the excited carrier density. While conventional low-intensity photoluminescence excitation spectroscopy reveals the quantization of the exciton's center-of-mass motion, two-photon absorption spectroscopy indicates that higher excitonic states are completely quantized by the lateral confinement. The energy positions are found to be in good agreement with one-dimensional (1D) subband calculations. Additionally, transitions between 1D subbands can be found under high excitation conditions. The singularity of the 1D-density of states is reflected by distinct peaks in the time resolved spectra of a dense electron-hole plasma, which is optically excited by high power laser pulses.
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