Microstructure control of sputtered Ba2TiSi2O8 films by sol-gel-derived underlayer

In this work, we used a sol-gel-derived layer to control the morphology and crystallinity of the fresnoite thin films produced by magnetron sputtering. Atomic force microscope (AFM) and Raman scattering spectra showed that the sol-gel-derived layer improves the crystallinity and morphology of the films as-sputtered. Compared to the film without the layer which gives a blur image of grains, fresnoite film with the layer presented sharp boundaries and distinct shapes, which is referred to the imprint of the layer's structure. Meanwhile, the difference in X-ray diffraction patterns and Raman spectra showed the different crystallinity of the films with or without the layer. It is suggested that the nanocrystalline layer fabricated by sol-gel method provides the nucleation site, and lower the energy barrier of the crystal growth in the sputtering of the thin films, thus making the thin films sputtered onto it with developed grains and the structural aspect of the layer.