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

Abstract

Ultrathin aluminum oxide films (≤20 Å thick) on Ru(0001) and Re(0001) surfaces have been grown by depositing aluminum in an oxygen ambient (0.5–1×10−5 Torr), 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 Å 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 (≥970 K). The LEIS results indicate three-dimensional growth for the films on these substrates at 1170 K. Films on Re(0001) show sharper LEED patterns than those on Ru(0001) substrates. Analysis of the XPS Al 2s/O 1s area ratios indicate that the films are stoichiometric.