An XPS study of Au alloyed Al-O sputtered coatings

► Nanocomposite films of Au clusters in an Al-O matrix were reactive-sputtered. ► The chemical bonding and the Au clusters size were studied by X-ray photoelectron spectroscopy (XPS). ► In the as-deposited films the Au is present from individual atoms to small clusters up to 1-2 nm. ► With annealing temperature, Au clustering in the dielectric matrix was observed.