Comparative crystal structure study of thin films of stoichiometric and non-stoichiometric titanium oxides

The crystal structure of thin films of stoichiometric TiO$_2$ and non-stoichiometric composition (TiO$_{2-\delta}$, $\delta$ =0.9) synthesized by ion beam sputtering deposition and annealed at temperatures of 723 $\div$ 973K in argon atmosphere has been studied. It was found that the films of stoichiometric composition crystallize by the dendritic growth mechanism at the initial stage. After the growth of dendrites before their interactions with each other, layered growth mechanism is observed with the formation of lamellar crystals. Films of nonstoichiometric composition crystallize according to the island growth mechanism. The activation energy of the crystallization front motion was determined for the dendritic growth mechanism, which was 2.3 eV. TiO$_2$ films after annealing consisted of plate-shaped crystals of rutile phase with inclusions of anatase nanocrystals. The films of non-stoichiometric composition were nano-dispersed, containing crystalline phases: anatase, rutile, $\alpha$-Ti$_3$O$_5$ and metallic $\alpha$-Ti.