Enhanced polarization and endurance properties of ZrO2-based ferroelectric capacitor using HfO2 interfacial layer

Recently discovered ferroelectricity in fluorite-structure ZrO2 thin film has attracted increasing and intense interest due to its lower crystallization temperature and higher content in nature in comparison to hafnium oxide. Here, the effect of HfO2 interfacial layer on the ferroelectric properties of ZrO2 thin films is investigated systematically by designing four types of interfacial structures. It is revealed that the ferroelectric orthorhombic phase, remanent polarization, and endurance can be improved in ZrO2 thin film by inserting both a top- and bottom-HfO2 interfacial layer. A maximal ferroelectric remanent polarization (2P(r)) of 53.4 mu C cm(-2) and an optimal endurance performance of 3 x 10(7) field cycles under frequency of 100 kHz are achieved in Pt/HfO2/ZrO2/HfO2/Pt capacitors, with ferroelectric stacks being crystallized at 450 degrees C via post-deposition annealing method. X-ray photoelectron spectroscopy analysis confirms that the HfO2 bottom-layer plays a very important role in the formation of a higher ratio o-phase, thus enhancing the ferroelectricity. These results suggest that designing appropriate interfaces would help achieve excellent ferroelectric properties in ZrO2 films.