A work function study of ultrathin alumina formation on Cu-9%Al(111) surface

We studied work function changes during oxidation of Cu-9%Al(111) surfaces at 900 and 670 K as a function of oxygen exposure in situ using ultraviolet photoelectron spectroscopy and Kelvin probe. The results showed that work function first decreased by 0.51 eV after 256 L O-2 exposure at 900 K, and then remained unchanged upon further oxygen uptake. The formation of the interfacial dipole layer was the main factor that determined work function and XPS binding energy shifts of Al2O3 energy levels at 900 K. The changes of work function and contact potential difference for amorphous Al2O3 formation at 670 K were similar to their trends at 900 K. The oxide over-layer structure showed little influence on the work function of the Al2O3/Cu-9%Al(111) system. Copyright (C) 2006 John Wiley & Sons, Ltd.