Study on the effect of ion beam bombardment during deposition on preferred orientation in rutile-type titanium dioxide films

Abstract

Rutile-type titanium dioxide films, which exhibits tetragonal structure, were synthesized by ion beam assisted deposition with ion beam incidence inclined 45° to the substrate. The influence of ion bombardment during deposition on the texture of films was studied. A change of preferred orientation from (110) to (200) with increase of ion to deposited atom arrival ratio was observed in case Ne+ and Xe+ ion bombardment were used during film growth, respectively. It is found that in rutile type TiO2 films (110) plane exhibits the lowest surface free energy and crystallites with (100) orientation have the widest channel to ions when ion beam injects with direction 45° to the film. The preferred orientation of titanium oxide films from (110) to (200) is accounted for in terms of channeling of ions and surface free energy. When arrival ratio of ion to atom is low, crystallites with (110) orientation which has lowest surface free energy grow preferentially. As the increase of arrival ratio, the damage induced by ion bombardment compresses the growth of crystallites with shallow ion channeling. Then (200) preferred orientation is observed because of its deep ion channeling. Compared to the cases Ne+ is used, lower arrival ratio is required to change the orientation from (110) to (200) for Xe+ bombardment, because heavier ion leads to stronger radiation damage.