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A new impedance spectroscopy unit is developed, fully customized to become a vital part of label free biosensor arrays with possible applications in DNA and protein sensing. Test measurements are conducted to explore the accuracy and specificity of the system, both under electronic lab conditions as well as under wet cell conditions with synthetic-diamond based sensor electrodes. The impedance of seven resistors was monitored for 17 h and a maximum error <0.02% was found. Furthermore, the impedance of PBS at different concentrations was monitored for 60 min per concentration and a different impedance for each concentration was detected. The impedance is also monitored for NaOH, PBS and nuclease free water at different temperatures with a total duration of 60 min per fluid. Systematically different impedances for each temperature per fluid were found and the temperature coefficients were determined. All test measurements lead to results well within specification.

In this article, we report on the synthesis of thin, epitaxial films of the transparent conductive oxide Al:ZnO on (0001)‐oriented synthetic sapphire substrates by DC sputtering from targets with a nominal 1 at.% Al substitution. The deposition was carried out at an unusually low substrate temperature of only 250 °C in argon–oxygen mixtures as well as in pure argon. The impact of the process–gas composition on the morphology was analysed by transmission electron microscopy, revealing epitaxial growth in all the cases with a minor impact of the process parameters on the resulting grain sizes. The transport properties resistivity, Hall effect and magnetoresistance were studied in the range from 10 to 300 K in DC and pulsed magnetic fields up to 45 T. While the carrier density and mobility are widely temperature independent, we identified a low field–low temperature regime in which the magnetoresistance shows an anomalous, negative behaviour. At higher fields and temperatures, the magnetoresistance exhibits a more conventional, positive curvature with increasing field strength. As a possible explanation, we propose carrier scattering at localised magnetic trace impurities and magnetic correlations. Cross‐sectional HAADF‐STEM image of an Al:ZnO film grown without oxygen in the sputtering gas. The inset is a false‐colour [100] high resolution STEM image (inverted annular bright field: green, annular dark‐field: red) of the ZnO crystal structure.