Characterization of spin-state tuning in thermally annealed semiconductor quantum dots

We report a systematic study of magneto-optical properties in CdZnSe/ZnSe semiconductor quantum dots (QDs) subjected to postgrowth thermal annealing. The theoretical and experimental characterizations are combined in order to understand the evolution of Zeeman splitting and the blueshift as well as redshift of the magnetic subcomponents with magnetic field strength of excitons confined in annealed QDs as a function of different annealing times. A combination of a multiband model as well as parameter interpolation supported by ab initio calculations is presented and points toward an inversion of the light-hole-heavy-hole states due to annealing. The band mixing of exciton states explains besides the variation in the Zeeman splitting for differently annealed QD excitons, the evolution of the diamagnetic blueshift into a paramagnetic redshift of the magnetic subcomponents. A discussion of the effects associated to the Coulomb interaction on the polarized excitonic recombinations modulated by magnetic field is given.