Structural investigations of the Yb  Si(111) - 2x1, 5x1 and 3x1 overlayers

The YbSi interface has been investigated in the sub-monolayer regime employing Ion Scattering Spectroscopy (ISS), Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). Three different structures, YbSi(111) 2x1, YbSi(111) 5x1, and YbSi(111) 3x1, have been established by heat treatments of the interfaces. The structures consist of a stable overlayer of Yb atoms on the Si(111) surfaces. The distance of the Yb atoms to the uppermost layer of Si atoms has been estimated by comparing the YbSi ISS intensity ratio with the predictions of a model based on classical scattering theory and a Thomas-Fermi-Moliére potential. The height of the Yb atoms relative to the substrate toplayer was found to be 1.9 ± 0.3→.