Theory of the optical properties of III-V semiconductor quantum wells
The aim of this project is to investigate the electronic and optical properties of III-V semiconductor quantum wells, specifically those based on the GaAs-AlGaAs system. Both the linear and non-linear optical properties of these systems are considered. A theoretical model for the refractive index in GaAs-AlGaAs quantum well structures for optical frequencies close in energy to the fundamental band gap has been constructed, and is based on knowledge of the electronic band structure. This model includes the valley states, and also allows for inclusion of the electronic states at the X and L points. The ground state and excited state excitons have also been explicitly included within the theoretical model. The exciton model which is employed in this thesis takes into account the Coulomb coupling between different exciton states. In addition, the effects of band filling and screening have both been incorporated, allowing the intensity-dependent index of refraction to be obtained. Calculations are presented for a range of material compositions and quantum well structures, including both single and double quantum wells. The results obtained for the index of refraction are therefore more complete and accurate than any previous published calculations. It is expected that the results presented here can be used directly in the design of refractive-based optoelectronic devices.