ELECTRONIC-STRUCTURE OF IRON SILICIDES GROWN ON SI(100) DETERMINED BY PHOTOELECTRON SPECTROSCOPIES

We have studied the growth of Fe on Si(100)2 X 1 and the formation of FeSi and beta-FeSi2 by solid-phase epitaxy and reactive-deposition epitaxy. The silicide films were characterized by x-ray photoelectron spectroscopy to determine their atomic stoichiometry and their characteristic plasmon loss structure. Bulk single crystals of FeSi and alpha-FeSi2.3 were analogously characterized, which allowed us to establish the nature of the in situ grown silicide films. The electronic structure of these FeSi and beta-FeSi2 films were carefully studied by ultraviolet photoelectron spectroscopy, and compared with previously published theoretical calculations. A clear difference between the valence-band features of FeSi and beta-FeSi2 was observed, which allowed us to monitor their appearance during the growth process, and to optimize the relevant experimental parameters in order to obtain the desired phase and improve the quality of its epitaxy.