Ultra thin Al2O3 films grown on Ni3Al(1 0 0)

The oxidation of the Ni3Al(1 0 0) surface at 1100 K with 2000 l was investigated by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), high resolution electron energy loss spectroscopy (EELS), and scanning tunneling microscopy (STM). Oxidation at 1100 K, leads to the formation of a well ordered, ultra thin Al2O3 film on top of Ni3Al(1 0 0). The oxide grows with the (1 1 1) plane of the γ′-Al2O3 parallel to the surface plane of the substrate. The observed LEED pattern of the Al2O3 film is explained by a hexagonal structure in two domains which are perpendicularly oriented with respect to each other. The lattice constant of the hexagonal structure amounts to ∼3 Å. In addition, two hexagonal superstructures with a lattice constant of 17.5 and 54 Å were found on the oxide surface.