Nucleation-driven ferroelectric phase formation in ZrO2 thin films - What is different in ZrO2 from HfO2?

Ferroelectric phase formation of ZrO2 thin films is discussed by paying attention to the film deposition process and doping into ZrO2, by comparing with the HfO2 counterpart. The results are showing a considerable difference between ZrO2 and HfO2 in terms of the stability against thermal annealing process. It is inferred that this is likely to be originated from the activation energy difference in the structural phase transitions from tetragonal to orthorhombic and subsequent orthorhombic to monoclinic phase transitions.