Enhanced polarization and endurance properties of ZrO₂-based ferroelectric capacitor using HfO₂interfacial layer

Recently discovered ferroelectricity in fluorite-structure ZrO₂thin 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 HfO₂interfacial layer on the ferroelectric properties of ZrO₂thin 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 ZrO₂thin film by inserting both a top- and bottom-HfO₂interfacial layer. A maximal ferroelectric remanent polarization (2P_r) of 53.4μC cm^-2and an optimal endurance performance of 3 × 10⁷field cycles under frequency of 100 kHz are achieved in Pt/HfO₂/ZrO₂/HfO₂/Pt capacitors, with ferroelectric stacks being crystallized at 450 °C via post-deposition annealing method. X-ray photoelectron spectroscopy analysis confirms that the HfO₂bottom-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 ZrO₂films.