On the properties of nanostructured titanium oxide thin films

Titanium oxide thin films were deposited by d.c. reactive sputtering onto different substrates (glass, silicon, quartz), at different temperatures (70–450 ∘C), using O2 or H2O vapors as reactive gases. X-ray diffraction patterns show that the percentage of the crystalline phases (anatase and rutile) strongly depends on the deposition conditions. Nanostructured films, with a mixed anatase/rutile structure were obtained when depositing onto glass substrates, while a pure rutile structure developed onto silicon substrates, the films being deposited in the same deposition run. Using O2 as reactive gas, both anatase and rutile phases are present in films deposited onto glass and quartz substrates.Fourier transform infrared spectroscopy measurements, performed in the wavenumber range from 300 cm−1 to 4000 cm−1, give us useful information on the characteristics of bond configurations for titanium oxide films, indicating the presence of a small amount of the water in the films obtained with water vapor as reactive gas.The temperature dependencies of the electrical conductivity were studied in a wide range of temperatures (from 13 K to 535 K).