Growth, interfacial alloying, and oxidation of ultra-thin Al films on Ru(0001)

The growth and oxidation of ultra-thin aluminum films on Ru(0001) have been studied by low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) using both Mg K alpha and synchrotron soft X-ray radiation. For Al films of average thickness similar to 15 Angstrom deposited at 300 K, LEIS demonstrates that the Ru substrate is completely covered. Upon annealing to similar to 1000 K LEIS shows the reappearance of Ru at the surface. At the same time, the metallic Al2p peak shifts to lower binding energy and a low binding energy shoulder appears on the Ru3d peak, suggesting Al/Ru interfacial alloying. Annealing Al films to similar to 1000 K in 1 X 10(-4) Torr oxygen produces an oxidized surface layer that completely covers the Ru substrate; the resultant aluminum oxide films are stoichiometric.