Optimized magnetron sputtering process for the deposition of gadolinia doped ceria layers with controlled structural properties

Gadolinia doped ceria (GDC) films have been deposited using reactive magnetron sputtering and the influence of the deposition parameters on the properties of the films has been investigated. The oxygen flow rate, the target-substrate distance and the radio frequency substrate bias have been varied and films were deposited with a relatively high power-normalized growth rate of 15-18 nm min(-1) W-1 cm(2). Depending on the target-substrate distance and on the oxygen flow rate fully oxidized as-deposited films or sub-stoichiometric films requiring an ex-situ thermal annealing step were obtained. These two manufacturing routes (direct deposition of a fully oxidized compound or post-oxidation of a sub-stoichiometric oxide) lead to different preferential orientations ([200] or [111]) of the final oxide film. This is attributed to the oxygen/metal flux ratio, which is modified according to the experimental configuration and the process parameters. Furthermore, the substrate bias was found to further the [111] orientation and thus playing with this parameter allows a fine tuning of the preferential orientation.