Crystallization of amorphous superlattices in the limit of ultrathin filmswith oxide interfaces

Annealing of amorphous Si/SiO2 dr Ge/SiO2 multilayers produces nanocrystals embedded between oxide interfaces. It is found that the crystallization te mperature is strongly enhanced by the presence of the oxide interfaces and follows an exponential law. The crystallization temperature increases rapid ly with decreasing Si layer thickness, and a nonstoichiometric interface de creases the crystallization temperature compared to a stoichiometric interf ace of the same thickness. A model is presented that takes into account the interface energies, the thickness of the layer, the melting point of the s ystem, and the crystallization temperature of the thick amorphous layer. Th e evidence for a critical crystallization radius and the influence of devia tions from a perfect stoichiometric interface are discussed.