DIFFERENT OXIDATION-STATES OF POLYCRYSTALLINE MOLYBDENUM TREATED BY O-2-PLASMA OR O-2-ION BOMBARDMENT

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 Mo6+ and residue assigned to Mo4+ and Mon+ with n<4. Those samples treated with plasma showed three peaks re sulting from signal superposition, mainly of Mo-0, Mo6+, a small contr ibution of Mo4+ and Mon+. In the region of the Mo-MNN Auger transition s (150-240 eV), three new peaks appeared upon oxidation. at similar to 5 eV lower kinetic energy than in Mo-0. The relative intensities with in each pair of peaks at 160, 186, and 221 eV depend on the oxidation method, i.e. on the kind of oxide formed. (C) 1998 Elsevier Science B. V. All rights reserved.