Abstract
By using transmission electron microscopy on as-grown and annealed GaInNAs/GaAs heterostructures, we demonstrate that annealing induces a correlated behavior of both In and N species within the GaInNAs quantum well. While no intermixing occurs, the analysis of the strain situation reveals that the main driving force for the observed inward diffusion is not composition gradients at the interfaces, but local strain fields. This mechanism leads to the improvement of the photoluminescence (PL) properties and to the blueshift of the PL peak.