Ion beam-induced carbide formation at the the titanium-carbon interface

In this paper we report on the carbidization of thin Ti films on graphite (Ti/C) and carbon films on Ti substrates (C/Ti) due to bombardment with noble gas ions (Ar+ and He+) at room temperature. The chemical state of the films is investigated by X-ray photoelectron spectroscopy (XPS). Directly after evaporation of the Ti (and C films, respectively) on the substrates about one monolayer of TiC is detected. Subsequent ion bombardment can lead to a complete conversion of elementary carbon into carbide. Spectra recorded during Ar+ and He+ depth profiling of Ti/C films with ion energies in the range between 0.5 and 4 keV clearly show the existence of TiC at the interface. The total amount of TiC formed increases with ion energy indicating a more effective ion beam mixing at higher energies. At 4 keV Ar+ ion energy all Ti at the interface is detected as carbide resulting in a composition of stoichiometric TiC. The C/Ti samples show in addition to TiC a distribution of titanium subcarbides