Fine structure of excitons: a sensitive tool for probing the symmetry of self-assembled quantum dots

We have performed magneto-photoluminescence spectroscopy of self-assembled In(Ga)As/GaAs single quantum dots. Both strength and orientation of the magnetic field have been varied. Symmetry of the dot structures as well as its breaking cause characteristic features in the optical spectra, which are determined by the electron–hole exchange and the Zeeman interaction of the carriers. The symmetry breaking can be either dot inherent due to geometry asymmetries or it can be obtained by applying a magnetic field with an orientation different from the dot symmetry axis.