FORMATION AND ELECTRONIC-PROPERTIES OF ERBIUM SILICIDE ON SI(100)

The formation of erbium silicide ErSi1.7 interface and thin films on p lane and stepped Si(100) surfaces have been investigated by low-energy electron diffraction (LEED), photoelectron spectroscopy (XPS and UPS) and Auger electron spectroscopy (AES). For the interfaces, approximat ely 0.3-2 ML of Er was evaporated on the substrate and subsequently an nealed at 400-600-degrees-C. For the thin films the co-evaporation met hod was used. On stepped Si(100) the surface state disappears less rap idly than on a plane one, suggesting a preferential clustering of the silicide along the steps. Upon annealing of the deposits (approximatel y 50 to 100 angstrom) a diffuse (2 x 2) LEED pattern is observed at 60 0-800-degrees-C. This pattern corresponds to a (2 x 1)ErSi1.7(1012BAR) . The valence bands show two main peaks at 1.3 and 2.8 eV and no dispe rsion in the surface plane, confirming the poor crystallinity of the f ilm. The results are discussed with those obtained for ErSi1.7/Si(111) .