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

摘要

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_2O_3 and TiO_2. These transformations do not affect the growth kinetics, since the film thickness showed a linear relation vs. the formation potential (Ef). On the other hand the exponential dependence of the density of donors (Nd), within the whole potential range of Ef, 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_2O_3 to TiO_2). Furthermore, the dependence of the flat band potential (E_(ft)) with E_f, is attributed to the composition of the oxide films formed by a mix of Ti oxides.