Electronic structure of epitaxial erbium silicide films on Si(111)

The present study is mainly motivated by the recent interest in rare-earth/Si interfaces for technological applications. Furthermore there is by now a rather poor understanding of their electronic structure. We present the first spectroscopic investigaton of epitaxial erbium silicide using angle-resolved ultraviolet photoemission spectroscopy (ARUPS) and low-energy electron diffraction (LEED). Thermal treatment at 700°C of a 15 monolayers Er deposit results in epitaxial ErSi1.7 formation characterized by sharp √3 × √3 R30° LEED pattern. The relevant ARUPS spectra exhibit essentially emission of Er4f multiplet states in the 4–11 eV binding energy window and structures at lower binding energies assigned to hybridized Er5d and Si 3sp states. Finally, we have shown that in contrast with pure Er, there is apparently no surface-related 4f component for monocrystalline ErSi1.7.