Correlations between structure and electrical properties of CrTa thin films prepared by oblique angle co-sputtering

CrTa thin films were deposited on glass and (100) silicon substrates by DC magnetron co-sputtering. Films were prepared by the glancing angle deposition (GLAD) method by fixing the deposition angle to 80° for both targets. The Cr and Ta target currents were systematically and reversely changed from 0 mA to 300 mA, so as to tune the composition of the films. All other working parameters were kept constant. For such GLAD co-sputtering conditions, the deposition time was adjusted in order to get a film thickness close to 400 nm. A columnar microstructure was obtained with a Janus-like architecture as a function of the operating target currents. Different morphologies and tilted column angles were produced by adjusting target currents. The typical hexagonal Cr phase was produced for Cr-rich films, whereas a mixture of α and β-Ta phases for Ta-rich films. DC electrical resistivity vs. temperature showed the typical metallic-like behaviors for all CrTa films. The electron-phonon and electron-defect interactions were investigated, and correlated with variations of the film's composition and structure.