If the oxygen pressure is too high, (partly) polycrystalline films grow due to insufficient scavenging power, mainly caused by overoxidation of the plasma and regrowth of the native oxide. Note that the crystallization times correlated well with the crystalline quality of the grown films. In general, low crystallization times led to low FWHM of the YSZ (002) rocking curves (compare Figs 2b and 3b), since both silicide formation and overoxidation of the plasma were avoided.