Angular distribution XPS studies on recoil-implanted substrates: Au in Al2O3

Angular distribution XPS has been employed for the first time to follow the changes in the electronic structure of gold as it is implanted into Al₂O₃ overlayers on aluminium by recoil. The rudimentary aspects of the implantation process may be followed by observing the Au 4f_{$\text{7}\text{2}$} intensity as a function of primary ion dose for discrete values of θ. Intensity versus primary ion dose curves show three distinct regions — a continuous-film region, an island and cluster region, and an implanted-atom region. For this system, while only gold atoms are introduced into the substrate, the surface contains clusters of gold even for very low gold concentrations. The valence-band density of states shows good agreement with a theoretical spectrum calculated using a unity polarizability model previously described.