Influence of oxygen flow and film thickness on the texture and microstructure of sputtered ceria thin films

An in depth understanding of the influence of the deposition parameters on the texture and microstructure of sputtered ceria thin films could pave the way towards the optimization of doped ceria thin films to be applied as fuel cell related electrolytes. In this work, ceria thin films were deposited at constant current using DC reactive magnetron sputtering. The influence of the oxygen flow and the film thickness on the crystallographic orientation and microstructure was studied. 200 nm thick films exhibit a change in out-of-plane orientation from random to preferential that coincides with the transition from metallic to poisoned mode. The preferential out-of-plane orientation of the films deposited in metallic mode changes from random to [200] as a function of both thickness and oxygen flow. Hence, films deposited in this mode are identified as grown under zone T conditions which agrees with scanning electron microscopy cross sections. In poisoned mode, however, a second transition is observed. The films deposited in this mode grow in zone II, but once more a change in out-of-plane orientation from [200] to random occurs when the oxygen flow is increased to higher values. - Highlights: • The discharge voltage behaviour for the Ce/O₂ system was measured. • Local oxygen addition allowed to deposit fully oxidized thin films. • The film texture was studied as a function of the oxygen flow and film thickness