From the artificial atom to the Kondo-Anderson model: Orientation-dependent magnetophotoluminescence of charged excitons in InAs quantum dots

Abstract

We present a magneto-photoluminescence study on neutral and charged excitons confined to InAs/GaAs quantum dots. Our investigation relies on a confocal microscope that allows arbitrary tuning of the angle between the applied magnetic field and the sample growth axis. First, from experiments on neutral excitons and trions, we extract the in-plane and on-axis components of the Landé tensor for electrons and holes in the s-shell. Then, based on the doubly negatively charged exciton magneto-photoluminescence we show that the p-electron wave function spreads significantly into the GaAs barriers. We also demonstrate that the p-electron g-factor depends on the presence of a hole in the s-shell. The magnetic field dependence of triply negatively charged excitons photoluminescence exhibits several anticrossings, as a result of coupling between the quantum dot electronic states and the wetting layer. Finally, we discuss how the system evolves from a KondoAnderson exciton description to the artificial atom model when the orientation of the magnetic field goes from Faraday to Voigt geometry.

Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

“…For QDs with C 2v symmetry only two optical branches are usually observed when the magnetic field is applied parallel to the QD high-symmetrxy axis. Any tilt between the magnetic field axis and the axis of high symmetry of the QD mixes the M = 1 and M = 2 states and allows the observation of four distinct optical transition [26,47,51]. However, the MPL properties of QDs with less common symmetries may differ significantly from what is observed for C 2v QDs.…”

Charge state control in single InAs/GaAs quantum dots by external electric and magnetic fields

“…Recently, coupling between triply negatively charged states and the wetting layer has also been shown using magneto-photoluminescence [34,35]. Up to now, only a few works have been reported on the charge state control by applying an external magnetic field [23,24].…”

Complex optical signatures from quantum dot nanostructures and behavior in inverted pyramidal recesses

“…We show in Figure 10 (a,b) [45,48,49,50]. Finally, we plot in Figure 12(b) the angle-dependence of the exciton Landé factor (g) measured for the bright states of CQD1 and CQD2 as a function of  and (ϕ), respectively.…”

“…The measure of the diamagnetic coefficient () is of particular interest, as this quantity is proportional to the exciton correlation length in the plane perpendicular to the direction of B 40,41,42 . Measuring  for various orientations of B thus allows extraction of the shape of the investigated QD, a method that has already been applied successfully to interfacial QDs, 43,44 Stranski-Krastanov QDs, 45 and quantum disks in nanowires 46 .…”

“…The latter may result from heavy-hole light-hole mixing 51,52 and also from some spreading of the hole wave function in the barrier of the LQWR in the direction parallel and perpendicular to the LQWR axis 45 .…”