High-throughput study of the anodic oxidation of Hf–Ti thin films

A comprehensive study of the anodic oxide formation on Hf–Ti alloys over the entire range of composition was conducted. Combinatorial thin film libraries were prepared by co-sputtering. HRSEM and XRD were used to characterize the thin films and to confirm that a continuous change of the composition was obtained for this fully miscible system. Electrochemical investigations were performed by means of an automatic scanning droplet cell with a droplet radius of 100 μm. Subsequent potentiodynamic scans with intermittent impedance measurements allowed a quantitative determination of film formation factor and dielectric constant for each composition with a resolution of 0.5 at.%. Mott–Schottky analysis of the oxides was used to evaluate the relationship between parent metal composition and oxide properties, namely flat band potential and donor density. The structure–property and composition–property relationships are discussed in detail.