  Molecular beam epitaxy of Fe3Si on GaAs(001) is studied in situ by grazing
incidence x-ray diffraction. Layer-by-layer growth of Fe3Si films is observed
at a low growth rate and substrate temperatures near 200 degrees Celsius. A
damping of x-ray intensity oscillations due to a gradual surface roughening
during growth is found. The corresponding sequence of coverages of the
different terrace levels is obtained. The after-deposition surface recovery is
very slow. Annealing at 310 degrees Celsius combined with the deposition of one
monolayer of Fe3Si restores the surface to high perfection and minimal
roughness. Our stoichiometric films possess long-range order and a high quality
heteroepitaxial interface.
