Laser desorption ionisation quadrupole ion trap time-of-flight mass spectrometry of titanium-carbon thin films.

RATIONALE

Titanium-carbon (Ti-C) ceramic thin films (abbreviated as n-TiC/a-C:H) are very important for industrial applications. However, their chemical structure is still not completely resolved. The aim of this study was to determine the chemical composition of such n-TiC/a-C:H layers prepared by balanced magnetron sputtering under various experimental conditions.

METHODS

Mass spectrometric analysis of Ti-C thin films was carried out via laser desorption ionisation (LDI) using a quadrupole ion trap and reflectron time-of-flight analyser. The stoichiometry of clusters formed via laser ablation was determined, and the relative abundances of species for which the isotopic patterns overlaps were estimated using a least-squares program.

RESULTS

Ti-C films were found to be composites of (i) pure and hydrogenated TiC, (ii) titanium oxycarbides, and (iii) titanium oxides of various degrees of hydrogenation (all embedded in an amorphous and/or diamond-like carbon matrix). Hydrogenated titanium oxycarbide was the main component of the surface layer, whereas deeper layers were composed primarily of TiC and titanium oxides (also embedded in the carbon matrix).

CONCLUSIONS

Mass spectrometry proved useful for elucidating the chemical structure of the hard ceramic-like Ti-C layers produced by magnetron sputtering. The Ti-C layers were found to be complex composites of various chemical entities. Knowledge of the resolved structure could accelerate further development of these kinds of materials.