  The growth of ultra-thin layers of Fe on the vicinal Pt(997) surface is
studied by thermal energy He atom scattering (TEAS) and Auger electron
spectroscopy (AES) in the temperature range between 175K and 800K. We find
three distinct regimes of qualitatively different growth type: Below 450K the
formation of a smooth first monolayer, at and above 600K the onset of bulk
alloy formation, and at intermediate temperature 500K - 550K the formation of a
surface alloy. Monatomic Fe rows are observed to decorate the substrate steps
between 175K and 500K. The importance of the high step density is discussed
with respect to the promotion of smooth layer growth and with respect to the
alloying process and its kinetics.
