ELECTRONIC-PROPERTIES OF EPITAXIAL ERBIUM SILICIDE

The electronic properties of erbium silicide thin films epitaxially grown on Si(111) have been investigated by X-ray and UV photoemission. The crystalline quality has been checked by low-energy electron diffraction. XPS indicates very weak charge transfer and metallic bonding in the silicide phase. The Si 2p core-level and the Auger transition Si KLL present double structures revealing two types of Si sites, the first one attributed to Si atoms in normal sites in the silicide and the second one to Si atoms in the vicinity of the vacancies and (or) the Si substrate portions seen through the holes of the film. The UPS valence band of about 4 eV width and formed of Er(6s5d)-Si(3s3p) hybridized states disperses weakly in the direction perpendicular to the surface and strongly in the surface plane. This valence band is compared to the ones already measured on YSi approximately 1.7 and GdSi approximately 1.7 and to the calculations made for YSi2.