engleski

Oxidation of nickel surfaces by low energy ion bombardment

Nickel oxide (NiO) is a good example of a p- type semiconducting oxide, with a wide range of possible applications, from electrochromic devices or chemical sensors to antiferromagnetic layers in spin valve structures. The quality of devices depends critically on the electrical properties of NiO films, thus it is important to fully understand the oxidation mechanisms of nickel that seems to be quite complex. We have shown recently that thin NiO films can be formed by bombardment of Ni surfaces with low energy oxygen ions. In the present study, we compare the formation of NiO films by the O2+ ion bombardment in the energy range of 0.5 - 5 keV with the thermal oxidation (RT to 500 oC) in oxygen atmosphere within an analytical ultrahigh vacuum chamber. The NiO films were analysed by X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) in order to determine different oxidation stages, stoichiometry and thickness of oxide films. We show that low energy oxygen- ion bombardment produces compact, more ordered and less amorphous oxide structures than films formed by some electrochemical methods.

XPS; nickel oxide; ion-bombardment; SIMS; thermal oxidation

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