The evolution of the Sb/Si interface at room temperature on the Si(1 1 1)-(7 7) and the Si(1 0 0)-(2 1) reconstructed surfaces

The difference in the interface formation of Sb on Si(1 1 1)-(7 7) and Si(1 0 0)-(2 1) surfaces is studied by in situ adsorption at room temperature and its characterization by X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) in ultra-high vacuum (UHV). Sb uptake is monitored by acquiring Si(2p) and Sb(3d) core-level spectra, which are de-convoluted into Gaussian components, at various submonolayer coverages. At the low Sb flux rates adopted, as the Sb/Si(1 1 1) interface is formed, the metallic nature of the Si(1 1 1)-(7 7) surface is seen to act as a barrier to the Schottky barrier formation, while band-bending monotonically increases to a saturation value on the Si(1 0 0)-(2 1) surface. The results suggest that the Si(1 1 1)-(7 7) reconstruction remains intact up to a critical coverage of 1.0 monolayer (ML) after which it transforms abruptly into a (1 1) phase. This behavior of Sb/Si interfaces is discussed in terms of the dimer-adatom-stacking fault (DAS) model for the Si(1 1 1)-(7 7) and the dimer row reconstruction of the Si(1 0 0)-(2 1) surface.