Characteristics of graded TiO2 and TiO2/ITO films prepared by twin DC magnetron sputtering technique

A twin DC magnetron sputtering system was used to prepare graded TiO2 and layered TiO2/ITO films on the unheated substrates. XRD analysis showed that the annealed TiO2 films contained more intensity of anatase phases and mixed with a little of rutile as compared with the as-deposited counterparts. The film morphologies, i.e., microstructure and surface roughness, were investigated by scanning electron microscopy and atomic force microscopy. The preferred orientation of the films along with surface morphology strongly depended upon the substrate materials and the post-heat treatment employed. X-ray photoelectron spectroscopy revealed that the films were heavily oxidized, regardless of post-heat treatment. The nanoindentation measurements on the films exhibited a comparatively higher hardness, Young's modulus and adhesive strength. One can conclude that the TiO2 samples with a highly homogenous and polycrystalline structure and with a controllable surface roughness can be produced by this sputtering technique and the post-heat treatment.