Role of the substrate in the C49–C54 transformation of $TiSi2$

In this work we report the results of the crystallographic and morphological characterization of $TiSi2$ films grown on a patterned and on a blanket Si substrate. We show that the C49 films grown on crystalline silicon exhibit a rougher surface with respect to that grown on polycrystalline substrate. The different surface morphology is maintained after transformation to the C54 phase. This latter is always (040) textured in the case of patterned films, whereas in blanket films texturing occurs only on a polysilicon substrate. The C49 phase displays (200) texturing when the film is grown on single crystalline Si(100), while random orientation of the grains is detected in the other cases. The experimental indications are associated with semiempirical total energy estimations of the surface energies for the two competing phases. From this comparison it turns out that, in the case of texturing, the preferential surfaces facing the substrate are the most energetic.