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(a) Energy-mapped (pseudo-color) PL intensity image of QWs for identification of green (arrows) and red (circles) emission centers, obtained at 500 W cm−2. PL intensity images of the same lateral area in absence of emission filters at excitation power density (PEx) of (b) 500 W cm−2, (c) 50 W cm−2, and (d) 5 W cm−2 (calibration bars denote counts pixel−1 s−1). PL spectra of a single red (e) and green (f) emission center obtained PEx between 3 W cm−2 (PMin) and 1 kW cm−2 (PMax).
Pump-power dependent single-spot TRPL decay traces for an individual (a) red and (b) green emission center, obtained by averaging the decay traces collected over tens of seconds. Arrows indicate increasing pump powers. The insets depict FLIM images of two different lateral areas of the QWs, each containing two (a) red or (b) green emission centers, as a function of increasing powers (I = IV < II = V < III = VI). The color-coded calibration bar represents the intensity weighted PL lifetimes for each pixel.
PEx dependence of (a) transition energy, (b) relative PL efficiency, and (c) spectral line-width for several individual emission centers, obtained from single-Gaussian fits to each power normalized PL emission spectra (a, inset). The green (filled symbols) and red (open symbols) LLCs are discriminated using their being above and below 2.09 eV (a, dotted line). Dashed lines are guide to visualize the trends.
Scatter plot of difference in transition energies (ΔETr) under screened and unscreened conditions as a function of , for 300 individual emission centers.
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