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

ABSTRACT

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 (2Pr) 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.