Effects of temperature on columnar microstructure and recrystallization of TiO2 film produced by ion-assisted deposition

Titanium oxide thin films were deposited by electron-beam evaporation with ion-beam-assisted deposition. The effect of the substrate temperature and annealing temperature on the columnar microstructure and recrystallization of titanium oxide was studied. The values of the refractive index varied from 2.26 to 2.4, indicating that the different substrate temperatures affected the film density. X-ray diffraction revealed that all films were amorphous as deposited. At annealing temperatures from 100 °C to 300 °C, only the anatase phase was formed. As the substrate temperature increased from 150 °C to 200 °Cto 250 °C, the recrystallization temperature fell from 300 °C through 250 °C to 200 °C. Changing the substrate temperature resulted in the formation of various types of columnar microstructure, as determined by scanning-electron microscopy. Different columnar structures resulted in different surface morphologies, as measured by atomic-force microscopy.