Interactions of Ti and its oxides with selected surfaces: Si(100), HOPG(0001) and graphene/4H-SiC(0001)

Abstract The paper presents an interaction of Ti/Ti-oxides with: Si(100), HOPG(0001) and graphene/4H-SiC(0001) substrates. A thin layer (~3 nm) of Ti was deposited by means of DC sputtering technique on all the considered substrates. XPS, AFM and Raman spectroscopy were applied to find out the differences in interaction of Ti/Ti-oxides with selected substrates under UHV annealing. In the case of Si(100), substrate, apart from the expected TiO2, the presence of TiSi2 and TiSiOx components and the easiest reduction towards Ti2O3 was observed under UHV annealing. The sample exhibited also substantial evolution of surface morphology without the change of surface roughness which was attributed to formation of TiSi2 and TiSiOx components. This was in contrast with HOPG substrate where an annealing-induced agglomeration of the deposited material increased the surface roughness substantially. However, in the case of Ti/Ti-oxides deposited on graphene/4H-SiC(0001), UHV annealing caused no noticeable change of surface morphology. Agglomerates were not formed which was attributed to degradation of graphene (confirmed by Raman spectra) and supressing van der Waals' interactions responsible for easy surface diffusion. The differences in morphology were also discussed in the context of the surface energy of selected substrates.