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Schematic of the samples and experimental setup. The QPs are vertically embedded in a GaAs matrix, while they are laterally surrounded by a QW-like matrix. The conduction band profiles along the posts and the matrix are shown schematically to the left and the right of the sample, respectively. Since the QPs are terminated by a QD at each end, their energy profile is modulated by strain. Also shown is the experimental configuration, where the near-infrared pump pulse and the THz probe pulse are normally incident onto the sample. is the time delay between the pump and probe pulses.
Results for the optical pump THz probe experiment on the QP sample for three different pump fluences at 10 K. The inset shows the normalized change in electric field on a short timescale.
(a) Results for the optical pump THz probe experiment on the QW sample for three different pump fluences at 10 K. The lower graph (b) shows the extracted decay times for the QW (blue) and the QP samples (black and red) at different pump fluences. The inset in (b) shows the fast decay component, followed by the intermediate decay (see text).
TRPL (false color plot) taken at 10 K from the 40 nm QP sample at excitation densities of (a) and (b) and the 40 nm QW sample (c). The time resolution of the streak camera was 15 ps.
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