Schematic drawing of a coupled CdSe-QD structure with a MW of .
Circularly polarized (: a solid line, : a broken line) cw-PL spectra and the circular polarization degree (a closed circle) at in a single SAQD layer (a), nonresonantly coupled SAQDs (b), and resonantly coupled SAQDs (c), respectively. Spectral peaks due to a direct exciton in the MW , a type-II transition , and a QD emission band are shown by arrows in the resonant sample.
-polarized excitonic PL spectrum at in the resonantly coupled QD structure with MW, where the spectrum was time integrated in the region from using a streak camera. The exciton PL spectra of the MW and QDs are shown by solid lines. The PL component due to the type-II transition is shown by a broken line.
Time dependences of (a thick line)- and (a thin line)-polarized PL intensities and the circular polarization degree (a solid circle) at in the resonantly coupled QD structure, for the PL-energy range of corresponding to the type-II transition. The value is defined as with the circularly polarized PL intensities, and .
(an open circle)- and (an open square)-polarized PL intensities and the circular polarization degree (a solid circle) as a function of time, in the single QD layer. The solid lines are fitted calculations using rate equations.
PL-peak energies of direct excitons in the MW (a solid square) and in indirect excitons (a solid circle) as a function of magnetic field (a). The QD spectral band is also shown by a dotted line. A fitted calculation for the direct exciton energy in the MW using a Brillouin function is shown as a function of magnetic field by a solid line. The energy with the decrement of 1-LO-phonon energy from the Brillouin fitting is also shown by a broken line. The calculated electron and hh energies in the MW as a function of magnetic field (b), where the origin of the vertical axis is set to be 0 at the top of valence band of bulk CdSe.
Schematic band alignment of the resonantly coupled QD structure with MW at , where the electron energy in the QD is assumed to be 1-LO-phonon-energy lower than the down-spin-electron level in the MW. Related carrier-spin dynamics and the type-II transition are also illustrated.
Time-resolved excitonic PL spectra integrated with the time window of , as a function of magnetic field. The type-II transition is shown to appear at .
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