Hole band engineering in self-assembled quantum dots and molecules

The electronic structure in type-II self-assembled quantum dots and molecules are discussed. As an example we consider disk-shaped InP/GaInP quantum dots. Depending on the thickness of the quantum dot holes are located inside (pillar case) or outside (flat-dot case), which implies that by varying the dot size one can engineer the position of the holes to establish either type-I or type-II confinement. In quantum-dot molecules we find that the strain leads to an upward shift of the lowest energies in all explored electron shells in both the double and triple dot molecules in the case of thick spacers, while for thin spacers the quantum mechanical coupling prevails, and a downward shift is observed. The exciton states are found to be strongly influenced by holes, which are able to turn bonding behavior of exciton levels into antibonding in a certain range of spacer thickness. The diamagnetic shift is computed for the coupled quantum dots, and the theoretical results are compared with available magneto-photoluminescence data.