Different oxidation states of polycrystalline molybdenum treated by O 2-plasma or O 2-ion bombardment

Abstract

The oxidation of Mo polycrystalline foils at room temperature, through O 2-ion bombardment and a reactive O 2 plasma studied by XPS and AES, is reported. Samples bombarded with O 2 ions showed Mo 3d XP spectra with two broad peaks, which can be deconvoluted with standard spectra of Mo 0, a small contribution of Mo 6+ and a residue assigned to Mo 4+ and Mo n+ with n<4. Those samples treated with plasma showed three peaks resulting from signal superposition, mainly of Mo 0, Mo 6+, a small contribution of Mo 4+ and Mo n+ . In the region of the Mo MNN Auger transitions (150–240 eV), three new peaks appeared upon oxidation, at ∼5 eV lower kinetic energy than in Mo 0. The relative intensities within each pair of peaks at 160, 186, and 221 eV depend on the oxidation method, i.e. on the kind of oxide formed.