Scanning droplet cell microscopy on a wide range hafnium-niobium thin film combinatorial library

A wide-range thin film Hf-Nb combinatorial library deposited by co-sputtering is studied. The microstructure and crystallographic properties of the thin film alloys locally investigated by SEM and GIXRD are mapped along the entire compositional spread from 14 to 94 at.% Nb. Scanning droplet cell microscopy (SDCM) is used for mapping the electrochemical properties of the naturally oxidised metallic surfaces. Anodisation of the Hf-Nb thin films alloys is achieved with a high throughput due to computer-controlled scanning, made with a composition resolution of 1 at.%. The electrical properties of the anodic oxides are mapped by EIS and a maximum electrical permittivity close to 75 was found for Hf-33 at.% Nb. Semiconducting properties of the mixed anodic oxides are studied using Mott-Schottky analysis and their composition and mixing is investigated by XPS depth profiling.