Interaction of Excitons in Two-Dimensional Potentials (Paperback)

In the present thesis we discuss experimental work related to the Bose-Einstein condensation (BEC) of bound electron-hole pairs (excitons) in GaAs coupled quantum wells. Coupled quantum wells were chosen because in these structures the lifetime of excitons can be extended to the mus range. In the experiments, by measuring their diffusion, we have proved that excitons can move freely in two dimensions, and we have proved that they can reach thermal equilibrium during their lifetime in a confining stress potential in the plane of the quantum wells. Having an equilibrium ensemble of these quasi-particles enabled us to measure their interaction potential in a controlled environment. We also introduce a simple theoretical model that accounts for the experimental findings on interaction. In the final chapter we discuss a new phenomenon at high stress, and evaluate its possible relation to excitonic BEC.