Strong biaxial texture and polymorph nature in TiO_2 thin film formed by ex-situ annealing on c-plane Al_2O_3 surface

摘要

Many applications based on TiO_2 thin films are strongly influenced by the film crystalline quality, microstructure and surface morphology. We have utilized x-ray scattering methods for crystal structure study of TiO_2 films, grown by DC reactive magnetron sputtering without heating. We have observed the formation of ordered phases after post-deposition ex-situ annealing in air at 600 ℃. The distinct biaxial texture with respect to the c-plane (0001) Al_2O_3 substrate surface, which developed during heating, shows remarkable patterns in pole figures. We have identified epitaxial relationships of anatase A(001)[110]|sub(001)[li00] and rutile R(100)[0011||sub(0001)[100] within single TiO_2 layer. In addition, within the same sample, we have observed the anatase in (112) orientation with two in-plane relationship options A(112)[110]||sub(0001)[2110] and A(112)[1101||sub(0001)[1100].