Electron spectroscopic studies of the Dy/Si(111) interface

Abstract

Low-energy electron diffraction (LEED), x-ray photoelectron (XPS), ultraviolet photoelectron (UPS), and Auger electron (AES) surface spectroscopic techniques were used to study the chemical interaction between Dy atoms and Si atoms at the Dy–Si interface at room temperature, as well as Dy silicides formed after annealing at 400 °C for 30 min. Experiment shows that at low coverages [≤4 monolayers (ML)] atom intermixing takes place, causing chemical shifts of Dy 4f and Dy 3d. However, no significant chemical shift of Si 2p has been observed, suggesting a lack of strong chemical bonds of the Dy–Si type. With coverage increasing, a (7×7) LEED pattern from a clean Si(111) surface turns into a (1×1), and finally becomes ambiguous. After annealing for 30 min at 400 °C, the Dy silicides formed with an atomic concentration ratio of Dy to Si of ∼1:2. The binding energies of Dy 4f (Dy Si2), Dy 3d(Dy Si2), and Si 2p(Dy Si2) are 5.5, 1295.2, and 98.65 eV, respectively.