INTERACTION OF ENERGETIC OXYGEN IONS WITH LITHIUM-CONTAINING AMORPHOUS HYDROGENATED CARBON-FILMS - A MASS-SPECTROMETRY STUDY

Lithium-containing amorphous hydrogenated carbon coatings (a-C:H/Li) h ave been prepared by a modified plasma assisted chemical vapor deposit ion (rf-PACVD) technique. In order to investigate the interaction of e nergetic oxygen with these films they were irradiated with oxygen ions of 3 keV energy. Erosion and retention behavior was measured by direc t detection of emitted particles using a differentially pumped line-of -sight quadrupole mass spectrometer. Results are compared to those of previous studies on pure and boron-containing carbon materials. Like i n these materials, emission of reaction products from a-C:H/Li is domi nated by CO and CO2, to a smaller extent also emission of lithium oxid e, Li2O, is observed. As compared to pure carbon the emission of react ion products is delayed, and the erosion yield after oxygen saturation of the surface layer is lower for lithium-containing films. Taking in to account results of X-ray photoelectron spectroscopy, it can be conc luded that the interaction of a-C:H/Li with energetic oxygen follows t he same general trends as observed for boron-containing carbon materia ls. However, chemical reactions and their dependence on conditions of irradiation are more complex in a-C:H/Li than in boron-containing carb on.