Electron diffraction observation of epitaxial silicon grown on a CaF2/Si(100) structure

Abstract

Growth and crystalline quality of epitaxial Si on a CaF₂/Si(100) structure have been investigated by in situ reflection high‐energy electron diffraction observation. Epitaxial Si/CaF₂/Si structures have been formed by vacuum evaporation using the technique of amorphous Si predeposition. It has been shown that the predeposited amorphous Si layer crystallizes epitaxially during subsequent heating, but contains twins in the film. The twins remain in the subsequently grown Si layer as thick as 100 nm. However, the twins no longer remain more than 100 nm thick in the epitaxial Si layer. Three types of superstructures have been found at the surface of Si/CaF₂/Si(100) structures for different Si epitaxial temperatures, and they have been related to the amount of Ca segregated at the surface.