Influence of Structure Transformations over the Growth and Semiconductor Properties of Ti Anodic Films in 0.1 M NaOH

Abstract

The electrochemical characterization of Ti anodic films during their growth in 0.1 M NaOH indicates structural changes related to the formation of different oxides i.e. TiO, Ti 2 O 3 and TiO 2 . These transformations do not affect the growth kinetics, since the film thickness showed a linear relation vs. the formation potential (E f ). On the other hand the exponential dependence of the density of donors (N d ), within the whole potential range of E f , is associated with the distribution of different oxides inside the film. The oxide with low oxidation state is near to the metal/oxide film interface and as going to the oxide film/solution interface, the oxides with higher oxidation state appeared (Ti 2 O 3 to TiO 2 ). Furthermore, the dependence of the flat band potential (E fb ) with E f , is attributed to the composition of the oxide films formed by a mix of Ti oxides.