Si/ErSi 1.7 interfaces and Si reepitaxy on the ErSi 1.7/Si structure

Abstract

The reaction of Si atoms with the ErSi 1.7(0001) surface and the reepitaxy of Si on the ErSi 1.7(0001)/Si(111) structure have been studied by LEED, XPS and angle-resolved UPS. For the interfaces, variable amounts of Si atoms, from ∼ 0.3 monolayer (ML) to ∼3 ML have been deposited on samples maintained at room temperature and the measurements have been carried out before and after annealing at 400–500°C. LEED observations show a fairly good stability of the surface structure with respect to deposited Si atoms. The characteristic √3 × √3 R30° pattern of ErSi 1.7(0001) remains visible until a surface coverage θ ≈ 1.5 ML and a (1×1) diagram is superimposed when deposits ≥ 0.75 ML are annealed. The surface states of the silicide are attenuated upon Si deposition but emerge again on the UPS spectra after annealing. XPS measurements indicate that small quantities of Si atoms are diffused into the silicide. Epitaxial growth of Si on the ErSi 1.7(111) structure is obtained when ∼ 20 to 30 Å of Si are annealed at 600°C on the latter. The epitaxial layer is characterized by its (7×7) LEED pattern and its surface states in the UPS valence band. A second ErSi 1.7(0001) thin layer has been also grown on the epitaxial Si, demonstrating the possibility of fabricating multilayers.