X-ray structural studies of epitaxial yttrium silicide on Si(111)

Abstract

We performed a series of glancing angle and reflection x-ray diffraction experiments to study both the in-plane and out-of-plane structure of epitaxial YSi2−x films grown on Si(111), with thicknesses ranging from 85 Å to 510 Å. These measurements allowed us to characterize the mean film lattice constants, the position correlation lengths of the film, and the presence and extent of strain as a function of film thickness. We find that the strain along the basal plane increases as a function of increasing thickness to approximately 1% in the 510 Å film; the corresponding out-of-plane strain is such that the film unit cell volume increases as a function of thickness. The corresponding in-plane microscopic strain varies from 0.5% for the 85 Å film to 0.3% for the 510 Å film. We relate our results to the mode of film growth and the presence of pinholes in the films.