FORMATION AND ELECTRONIC-STRUCTURE OF TERBIUM SILICIDE EPITAXIALLY GROWN ON SI(111)

The growth of epitaxial TbSi(x) (x approximately 1.7) on Si(111)-7 x 7 was studied using Low Energy Electron Diffraction (LEED), Photoelectron Spectroscopies (XPS, UPS, AES) and Work Function (WF) measurements. The silicide was formed by depositing a 70 angstrom Tb layer on Si at RT and subsequent annealing. Up to 900 K a 1 x 1 LEED pattern is observed and with further heating up to 1100K a square-root 3x square-root 3-R30-degrees superstructure appears. The XPS and AES results indicate that charge transfer between Tb and Si upon silicide formation is very weak, while Si derived states contribute to the valence band DOS of TbSi(x) close to the Fermi level. Angle resolved UPS for the two structures shows a band located just below the Fermi level in the vicinity of the M point of the hexagonal Surface Brillouin Zone.