Polarization dependences of electroluminescence and absorption of vertically correlated InAs/GaAs QDs

The results of experimental studies concerning the optical polarization anisotropy of electroluminescence and absorption spectra of systems with a varied number of tunnel-coupled vertically correlated In(Ga)As/GaAs quantum dots (QDs), built into a double-section laser with equal-length sections, are presented. One such system is a QD superlattice exhibiting the Wannier–Stark effect. The involvement of heavyhole ground states in optical transitions for light polarized both in the plane perpendicular to the growth axis ($X$–$Y$) and along the growth direction $Z$ of the structure was observed. The degree of polarization anisotropy depends on the height of vertically correlated QDs and the QD superlattice: the total thickness of all In(Ga)As QD layers and GaAs spacers between the QDs, which is related to the $Z$ component of the wave function of heavy-hole ground states for vertically correlated QDs and for the QD superlattice.