Exciton binding energies and diamagnetic shifts in semiconductor quantum wires and quantum dots

Systematic studies of the effects of confinement and reduced dimensionality on excitons in quantum wires and quantum dots have been made on systems with widely varying sizes. Diamagnetic shifts are obtained from low-intensity magnetophotoluminescence spectroscopy, and exciton binding energies are estimated using an anisotropic bulk exciton model. Modulated barrier and deep-etched ${\mathrm{In}}_{0.10}{\mathrm{Ga}}_{0.90}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ structures are used in order to study the dependence on the lateral potential offset. Calculations of the diamagnetic shifts and the binding energies are made using variational techniques, and are found to be in good agreement with experiment. For the sizes studied experimentally, the binding energies are found to be enhanced by up to four times the bulk value for wires, and by five times for dots. Further, confinement is found to have significant effects on the excitonic properties for structure sizes up to ten times the Bohr radius.