Interactions of hyperthermal TiClx+ (x=0-4) ions with graphite surfaces

The interactions of hyperthermal chlorotitanium ions, TiCx+ (x = 0-4) with HOPG surfaces were studied by low-energy ion scattering of TiClx+ from HOPG and by XPS depth profile analysis of the TiClx+ exposed HOPG surfaces. Pos itive ion scattering data for 5-500 eV collision energies showed exclusivel y dissociative scattering of the molecular TiClx+ into TiCl+ and Ti+ fragme nts. TiCl3+ and TiCl2+ daughter fragments were not detected in the surface- induced dissociation (SID) spectra of the corresponding larger incident TiC lx+ ions. The observed survival of > 100 eV TiCl3+ and TiCl2+ incident ions in the scattered ion spectra and the calculated trend in the electron affi nities of TiClx neutrals implicate the role of bond dissociation in the eff icient electron transfer to the departing TiCl3 and TiCl2 fragments during SID. XPS depth profile analysis showed a good correlation between the colli sion energy and the type of incident TiClx+ with the quality of TiC thin fi lms formed on the surface of HOPG. Higher collision energies resulted in hi gher carbidic C to Ti ratios and higher carbidization efficiencies whereas a larger number of Cl atoms in the incident TiClx+ ion gave lower stoichiom etries and lower carbidization efficiencies in the resulting films.