Influence of oxygen partial pressure adopted in separate heat-treatment steps on the epitaxy of LZO film

The influence of oxygen partial pressure on epitaxy is systematically studied in La2Zr2O7 (LZO) thin films fabricated by metal organic deposition (MOD) on yttria stabilized zirconia (00l) single crystal substrates. The results show that oxygen partial pressure affects not only the epitaxial growth but also the morphology evolution of film. It is observed that the texture sharpness of LZO film improves while its surface flatness becomes worse with increasing oxygen partial pressure during the whole heat-treatment process. Further studies illustrate that high oxygen partial pressure at pyrolysis step favors the texture sharpening of LZO film, which is contributed to the complete decomposition of organic constitution and the decrease of residual carbon in oxide film. However, low oxygen partial pressure at crystalline step helps the improvement of surface flatness for LZO thin film. It is supposed to be linked with the decrease of oxygen vacancy defects and the increase of grain size along with the replenishment of oxygen content at the crystallization stage. Tailoring oxygen partial pressure at separate heat-treatment steps is important to improving texture sharpness and surface flatness of LZO buffer film as long as the oxidation of metallic substrate can be avoided in coated conductors.