A work function study of ultra-thin alumina formation on NiAl(1Â 1Â 0) surface

We have investigated the oxidation of NiAl(1 1 0) surface at 1020 and 670 K using ultra-violet photoelectron spectroscopy, Kelvin probe, X-ray photoelectron spectroscopy and low-energy electron diffraction. The work function change during oxidation was monitored in situ as a function of oxygen exposure. It was observed that the work function decreased by 0.6 eV after 7.9 Å of well-ordered Al2O3 formation on NiAl(1 1 0) at 1020 K. The formation of the interfacial dipole layer was the main factor that determined the work function and XPS binding energy shifts of Al2O3 energy levels. The work function decreased by 0.8 eV after 5.1 Å of amorphous Al2O3 formation at 670 K. The oxide layer structure was one of the key factors that determined the work function of the Al2O3/NiAl(1 1 0) system.