Growth of ultrathin crystalline Al2O3 films ore Ru(0001) and Re(0001) surfaces

Ultrathin aluminum oxide films (less than or equal to 20 Angstrom thick) on Ru(0001) and Re(0001) surfaces have been grown by depositing aluminum in an oxygen ambient (0.5-1 x 10(-5) Ton), and have been characterized by x-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS), low energy electron diffraction (LEED), and high resolution electron energy loss spectroscopy. No LEED pattern is observed from the films of thickness > 5 Angstrom deposited on either surface at 300 K. Long range order of the films is achieved by depositing aluminum in ambient oxygen at elevated substrate temperatures (greater than or equal to 970 K). The LEIS results indicate three-dimensional growth for the films on these substrates at 1170 K. Films on Ru(0001) show sharper LEED patterns than those on Re(0001) substrates. Analysis of the XPS Al 2s/O 1s area ratios indicate that the films are stoichiometric. (C) 1996 American Vacuum Society.