Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

Abstract

Models of carrier dynamics in quantum dots rely strongly on adequate descriptions of the carrier wave functions. In this work we numerically solve the one-band effective mass Schrödinger equation to calculate the capture times of phonon-mediated carrier capture into self-assembled quantum dots. Comparing with results obtained using approximate carrier wave functions, we demonstrate that the capture times are strongly influenced by properties of the wetting layer wave functions not accounted for by earlier theoretical analyses.

Effect of phonon confinement on one- and two-polar optical phonon capture processes in quantum dots

“…Moreover, the capture time defined as τ = R 1/ has the same order of magnitude as that obtained by Magnusdottir et al without taking into account the phonon confinement [23]. It is seen that there exist bands of dot radii where capture is energetically allowed, in accordance with previous results [23,29]. This means that the appearance of these bands is not caused with phonon confinement.…”

“…It should be noted that in the capture rate dependence appear 7 and 4 bands for LO1-and IO-phonon coupling cases, respectively, when the QD radius changes from a 0.3 B to a 2 B . In addition, in contrast to previous results [23,29], which obtained without taking into account the phonon confinement, we found that the height of the peaks is lowered as QD radius decreases. It is natural to assume that this is due to spatial confinement of the phonon modes as the latter leads to a strong dependence of the electron-phonon interaction Hamiltonian on the QD radius.…”

Frequency dependence of the radiative decay rate of excitons in self-assembled quantum dots: Experiment and theory

“…Furthermore, we employ here a two-band description of the QD including the effects of a wetting layer and strain, which is sufficient to capture the essential properties of QDs. 33,34 The envelope function approach we use here is valid even for QD sizes as small as an atomic unit cell because the small effective masses and shallow confinement potentials in this system ensure that the envelope functions are slowly varying on the atomic scale even if the confinement potential is not. 35 The inclusion of more bands is important for studying excited states of quantum dots, but for ground-state transitions the effects are small.…”

Modulation response of quantum dot nanolight-emitting-diodes exploiting purcell-enhanced spontaneous emission

“…1. Notice that the model assumes local equilibrium between QD and wetting layer states, 9 which is consistent if the capture time, usually on the order of a few picoseconds or less, 10 is smaller than the inverse of the modulation frequency predicted by the model. Furthermore, scattering rates need to be low enough, a͒ Electronic mail: suhr@fotonik.dtu.dk.…”