Electron beam induced oxidation of Ni3Al surfaces: electron flux effects

Electron beam irradiation of polycrystalline boron doped Ni3Al (at 300 K and under ultrahigh vacuum conditions) induces fast oxidation. The rate and depth of oxidation initially increase with increasing electron flux as indicated by results from Auger electron spectroscopy. Curves of oxygen development were fitted using a kinetic model that assumes the creation of oxide nucleation centers by the electron beam. The corresponding cross-sections were extracted. For fluxes exceeding 1 mA/cm2, the oxidation rate is limited by the amount of oxygen present in the vacuum environment. For lower e-beam fluxes the oxidation process is slower with significant O chemisorption, resulting in shallower oxidation. These findings point out a way to control the thickness of nickel oxide in the nanometer range.