Oxidation of molybdenum surfaces by reactive oxygen plasma and O2+ bombardment: an auger and XPS study
✍ Scribed by López-Carreño, L. D.; Benítez, G.; Viscido, L.; Heras, J. M.; Yubero, F.; Espinós, J. P.; González-Elipe, A. R.
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 403 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
The oxidation of molybdenum at room temperature with oxygen plasma or a beam of ions has been studied O 2 ' with Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). Auger electron spectroscopy shows a progressive modiÐcation of the lineshape and the development of new features close to the intense N 2, 3 VV Auger transitions of metallic Mo at 160, 186 and 221 eV. The e †ects are greater with the oxygen plasma M 4, 5 NN than with the bombardment. X-ray photoelectron spectroscopy shows that the incorporation of oxygen into O 2 ' the molybdenum gives rise to the formation of Mo6', Mo4' and a form of Mon' (n AE 4). The (Mo4' + Mon')/Mo6' ratio was higher after ion bombardment than by treatment with the oxygen plasma, O 2 ' in which case the concentration of the Mo4' and Mo6' oxidation states was very similar. The analysis of the O 1s and O KLL Auger spectra under the di †erent conditions showed that whenever a high concentration of the Mo6' species is present, the O-Mo bond is more covalent in character. To evaluate the inÑuence of chemical and ballistic e †ects in the two oxidation processes, additional experiments were carried out with This oxide was bom-MoO 3 . barded with Ar' and until a steady-state surface composition was reached. In both cases, the formation of a O 2 ' considerable amount of Mo4' + Mon' (n AE 4) and Mo0 species (i.e. reduction of Mo6' initially present in the sample) was detected. These results suggest that the high concentration of Mo4' + Mon' found upon bombardment of Mo0 with is rather produced by ballistic e †ects, which cause the reduction of the initially formed O 2 ' Mo6'.