ALUMINUM THIN-FILM GROWTH ON A RU(0001) SURFACE

The growth of thin Al films on a Ru(0001) substrate has been investiga ted by means of AES, LEED, TDS, and PAX measurements. A plot of the Ru and Al AES intensities versus evaporation time for a deposition tempe rature of 300 K reveals a distinct break at theta(Al) = 1, while for h igher coverages the Ru intensity decays exponentially indicating a thr ee-dimensional growth of Al clusters. From this behavior we deduce a S transki-Krastanov growth mechanism. This behavior persists up to 650 K . For higher deposition temperatures a diffusion of Al into the substr ate and a partial desorption of the Al film is found. At low Al covera ge the LEED pattern reveals an initial film growth with Al(111) struct ure and an expansion of the interatomic spacing of 2% compared to the Al(111) bulk plane. This superstructure persisted up to similar to 2.5 ML. In the submonolayer regime CO and Xe TD-spectra as well as Xe4d P AX-spectra suggest together with LEED an island growth.