Copper clusters on Al2O3/NiAl(110) studied with STM

The structure of nanosize Cu clusters has been studied with scanning tunnel ling microscopy (STM). The clusters were deposited on a thin aluminium oxid e film created by oxidation of NiAl(110). The STM images show that the Cu g rows as 3D islands on the Al2O3 film, for the coverages studied (theta (Cu) less than or equal to 5 ML). For crystalline clusters larger than similar to 40 Angstrom, the top facet could be imaged with atomic resolution, revea ling a (111) facet. From the shape of the crystalline clusters information about the Cu surface energies has been extracted and compared to theoretica l values. From the height-to-width ratio of the Cu clusters the work of adh esion for Cu on the Al2O3 film could be determined to be 2.8 +/- 0.2 J/m(2) using theoretical values for the surface energies. (C) 2001 Elsevier Scien ce B.V. All rights reserved.