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

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 degree 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 x 7) LEED pattern from a clean Si(111) surface turns into a (1 x 1), and finally becomes ambiguous. After annealing for 30 min at 400 degree C, the Dy silicides formed with an atomic concentration ratio of Dy to Si of similar to 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