Thickness and structure change of titanium(IV) oxide thin films synthesized by the sol–gel spin coating method

• We propose the sol–gel prepared TiO2 thin films.
• We control the structural changes of TiO2 thin films with increase of temperature.
• XRD, Raman spectroscopy, AFM, ellipsometry methods were used to deep analysis of structure of thin films.

Titanium dioxide is a well-known material in nanotechnology, while it provides new opportunities due to its interesting properties, for example, as a semiconductor with a quite significant forbidden band gap energy of 3.2 eV. In this study, thin films of titanium dioxide (TiO2) were synthesized in amorphous and crystallographic systems using the sol–gel process. Atomic Force Microscopy (AFM), Raman spectroscopy and X-ray diffraction (XRD) techniques were applied to obtain structural characteristics of the prepared films. We estimated that TiO2 thin films crystallize in anatase phase between temperatures 380 °C and 700 °C, and into anatase–rutile phase at 650 °C, while rutile phase exists alone above 800 °C. The changes in porosity of materials in relation to temperature were calculated as well. The refractive index of titanium dioxide thin films from ellipsometric measurements is also provided.