INSITU AND EXSITU STRUCTURAL CHARACTERIZATION OF BETA-FESI2 FILMS EPITAXIALLY GROWN ON SI(111)

The structural properties of beta-FeSi2 films grown on Si(III) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as-deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fc thicknesses were calibrated by Rutherford backscattering. The behavior of the Fe(MVV)/Si(LVV) Auger peaks ratio intensity as a function of Fe thickness indicates a Stranski-Krastanov mode of growth. Annealing of the Fe layers at temperatures between 400 and 600-degrees-C led to the beta-FeSi2 formation. Sharp LEED patterns typical of the beta-FeSi2 orthorhombic structure were obtained. X-ray double-crystal diffraction was carried out on a film about 200 angstrom thick in order to determine the lattice mismatch between the beta-FeSi2 and the Si(III) planes accurately. The measured value of (2.1 +/- 0.1) x 10(-2) unambiguously indicates that (101) epitaxy takes place only on Si(III). No elastic strain of the overlayer was evident. The full width at half maximum of the overlayer diffraction peak indicates a good crystalline quality. An upper limit for mosaic spread was determined to be about 0.05-degrees.