Surface and interface study of U/Si (1Â 1Â 1)

Thin uranium films were deposited on Si (1 1 1)-7 × 7 surface by e-beam evaporation. The surface and interface of U/Si (1 1 1) with different annealing temperatures were studied by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED) and photoemission spectroscopy. The formation of 2D uranium silicide (USi1.67) film was confirmed by the presence of a sharp 1 × 1 LEED pattern, and the surface morphology of this phase displays triangular layered structures. A new superstructure was found for the U-Si system when annealing the interface at 1000 K. Further annealing of the interface leads to the appearance of large area of Si (1 1 1)-7 × 7 reconstruction surface with high islands on it.