Few-Particle Effects in Self-Organized Quantum Dots

Few-particle effects of zero-dimensional charge carriers in self-organized quantum dots (QDs) are investigated both experimentally and theoretically. The actual three-dimensional confinement potential is determined by the real-space geometry and chemical composition of a realistic QD, reflecting its low symmetry, the influence of inhomogeneous strain on the band structure, and piezoelectric effects. Calculations based on the eight-band k · p model combined with the configuration-interaction method (CI) are presented, yielding insight into the complex interplay of confinement potential and electronic structure. For the InAs/GaAs model system, the existence of both binding and anti-binding biexciton states is predicted and verified experimentally. For CdZnSe/ZnSSe QDs, model calculations are used to identify experimentally observed emission lines from the decay of neutral as well as charged exciton (X) and biexciton (XX) states. Here the variation of the binding energy and the finestructure splitting is attributed to a variation of material composition, i.e. Zn–Cd intermixing and the shape of the probed QDs, respectively.