title: Properties of anodic oxides grown on a hafnium-tantalum-titanium thin film library.
abstract: A ternary thin film combinatorial materials library of the valve metal system Hf-Ta-Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott-Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven.
authors.affiliation: Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Strasse 69, A-4040, Linz, Austria.
authors.forename: Andrei Ionut
authors.initials: AI
authors.lastname: Mardare
authors.affiliation: Institut für Werkstoffe, Ruhr-Universität Bochum, D-44780, Bochum, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: Institut für Werkstoffe, Ruhr-Universität Bochum, D-44780, Bochum, Germany.
authors.forename: Alan
authors.initials: A
authors.lastname: Savan
authors.affiliation: Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Strasse 69, A-4040, Linz, Austria.
authors.forename: Achim Walter
authors.initials: AW
authors.lastname: Hassel
keywords: Anodic oxide film; Combinatorial libraries; High-throughput experimentation; Scanning droplet cell microscopy