PHOTOELECTRON SPECTROSCOPIC INVESTIGATIONS OF THIN FEXSI100-X FILMS

Photoelectron spectroscopic methods (UPS, XPS) were employed to study the electronic properties of FexSi100-x films (0 less than or equal to x less than or equal to 75) in the amorphous and polycrystalline stat e. The amorphous samples were prepared by vapour condensation on sapph ire substrates held at room temperature (RT). The polycrystalline samp les were obtained by annealing the amorphous films at 950 K. An insula tor-to-metal transition in the amorphous films has been detected for F e content between 10 and 20 at%, as indicated by the development of a step-like photoelectron intensity at the Fermi level. The semiconducti ng beta-FeSi2 phase is observable in the polycrystalline films, as see n by the disappearance of the step-like Fermi edge in the UPS spectra. A line shape analysis of the Fe 2p core levels is used to obtain addi tional information about the electronic structure of the different pha ses. Our results will be compared to data taken on Fe/Si interface lay ers by other authors.