Abstract
The thermal stability of faceted self-assembled PbSe quantum dots during annealing is investigated. With increasing annealing time, the dot density is found to decrease rapidly with a simultaneous increase of the average island volumes. In addition, a shape transition from pyramidal islands to truncated pyramids is observed for islands exceeding a critical height of 160 Å. The evolution of island volumes and densities is consistent with Oswald ripening by interface-reaction-limited mass transfer. This is a clear indication that the as-grown islands do not represent an equilibrium structure and that their narrow size dispersion is a purely kinetic effect.