Comparison of hydrophilic properties of amorphous TiOx films obtained by radio frequency sputtering and plasma-enhanced chemical vapor deposition

The hydrophilic properties of amorphous TiOx films prepared by different methods, e.g.. radio frequency (rf) sputtering and plasma-enhanced chemical vapor deposition (PECVD), were studied. It was found that the hydrophilicity strongly depends on the film structure. The best hydrophilicity was realized with the PECVD amorphous film having distorted Ti-O bonds due to a large amount of OH groups. These characteristics of the PECVD amorphous film suggest that such a low-density film including distorted Ti-O bonds could increase the photoenhancement efficiency by ultraviolet radiation. This reason is also supported from the results that a low-density rf sputtered film presented a higher hydrophilicity compared to a high-density radio frequency sputtered film. Furthermore, both electrical and chemical effects of OH groups will also contribute to the good hydrophilicity of the PECVD film.