GROWTH OF ULTRATHIN IRON SILICIDE FILMS - OBSERVATION OF THE GAMMA-FESI2 PHASE BY ELECTRON SPECTROSCOPIES

In this paper, we report on the iron silicide formation when annealing 3-7-angstrom-thick Fe films deposited on Si(111) between 250 and 550- degrees-C. The growing films are characterized by Auger-electron spect roscopy, electron-energy-loss spectroscopy, low-energy electron diffra ction, and surface-extended energy-loss fine structure in order to inv estigate the film composition, crystallography, and local atomic envir onment. We show that, upon annealing at 500-degrees-C, FeSi2 in the Ca F2 phase is formed when the initial Fe coverage is less than 7 angstro m whereas beta-FeSi2 is formed when the Fe coverage lies above 10 angs trom.