X-RAY STRUCTURAL STUDIES OF EPITAXIAL YTTRIUM SILICIDE ON SI(111)

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 angstrom to 510 angstrom. 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 angstrom 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 angstrom film to 0.3% for the 510 angstrom film. We relate our results to the mode of film growth and the presence of pinholes in the films.