Structural and mechanical characterization of nanostructured titanium oxide thin films deposited by filtered cathodic vacuum arc

Titanium oxides are interesting materials, because they can be used for photocatalytic, optical and gas sensing purposes. In a variety of applications, the present phases and film structure have an influence on the effectiveness of the coating function: for this reason, deposition parameter control plays a fundamental role in the formation of coatings with the wished features. In this work, titanium oxide films are deposited by filtered cathodic vacuum arc (FCVA) operated in a pulse mode. FCVA is a versatile deposition system appreciated both in research and industry for its high deposition rate, for the possibility to control the ion energy and for the production of nearly fully ionized plasma. A pure titanium cathode is used as ion source, and depositions are carried out in an oxygen reactive atmosphere. The effects of substrate temperature and substrate bias on film properties, structure and composition are investigated. Bragg-Brentano X-ray diffraction, and electron and atomic force microscopy are used to assess the deposited film structure, while nanoindentation is used to study film mechanical properties. Phases, roughness, hardness and reduced Young's modulus are studied as a function of the deposition parameters. Correlation between deposition conditions and structure of synthesized films is discussed, taking into account the features of plasma produced by a filtered cathodic arc system. (C) 2013 Elsevier B.V. All rights reserved.