Achieving robust ferroelectric polarization in uncapped Hf0.5Zr0.5O2 thin films by incorporating Al dopant

In this study, we developed an uncapped HfO2-based ferroelectric (FE) film by incorporating Al dopants into Hf0.5Zr0.5O2 (HZO) films, offering a viable solution to eliminate the need for a top electrode. By systematically optimizing Al doping concentrations and annealing conditions, the Al:HZO film with a cycle ratio of 1:24 achieved a high remanent polarization (2Pr) of 39.5 μC/cm2 at a low thermal budget of 500 °C. The optimized Al:HZO film exhibited a nearly wake-up-free effect and stable polarization retention up to 108 cycles, demonstrating the robust endurance characteristics in the uncapped Al:HZO film. The XRD results indicate that Al doping suppresses the formation of the monoclinic phase and enhances the stability of the tetragonal phase, which may contribute to the enhanced ferroelectric performance and fatigue resistance of the uncapped Al:HZO films. Our results provide a simplified pathway for developing uncapped HfO2-based FE films, which is helpful for advancing HfO2-based FE films for use in next-generation nanoelectronic devices.