Influence of electron flux on the oxidation of Ni3Al surfaces

Electron beam currents of a few nanoamps, currently used in nanometer scale scanning Auger microscopy scanning electron microscopy, promote oxidation of polycrystalline Ni3Al to a degree that depends on the size of the beam a nd subsequently on the electron flux cp,. In fact, the oxidation of Ni3Al a t room temperature follows a model based on the premise that the electron b eam creates additional nucleation sites around which oxide growth occurs. W ith increasing beam size the oxidation process becomes slower and O chemiso rption plays a significant role. As a result the Ni-oxide depth decreases d rastically with an increasing spot size (or equivalently decreasing electro n flux). It offers an alternative way to monitor the NiO thickness in the n anometer range. (C) 2001 American Vacuum Society.