Enhancement of exciton binding energies in quantum wires and quantum dots

Low-intensity magneto-photoluminescence measurements of the diamagnetic shifts of modulated barrier In0.10Ga0.90As/GaAs quantum wires and quantum dots of widely varying sizes have been used to give results for the effects of confinement and of dimensionality on the binding energies of excitons. The binding energies are found to increase systematically with decreasing size and to increase in going from wires to dots of the same size. The increase in the binding energy is found to begin for sizes as large as 10 times the Bohr radius and to reach 3.5 times the bulk value. The experimental results for the exciton binding energies and for their diamagnetic shifts are in good agreement with detailed calculations for these structures.