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

The formation of erbium silicide ErSi1.7 interface and thin films on plane 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, approximately 0.3-2 ML of Er was evaporated on the substrate and subsequently annealed at 400-600-degrees-C. For the thin films the co-evaporation method was used. On stepped Si(100) the surface state disappears less rapidly than on a plane one, suggesting a preferential clustering of the silicide along the steps. Upon annealing of the deposits (approximately 50 to 100 angstrom) a diffuse (2 x 2) LEED pattern is observed at 600-800-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 dispersion in the surface plane, confirming the poor crystallinity of the film. The results are discussed with those obtained for ErSi1.7/Si(111).