Contribution of the interfacial oxygen vacancies on the asymmetric switching behaviors of the Al:Hf0.5Zr0.5O2 ferroelectric films

In this work, we investigated the effects of interfacial oxygen vacancies on the ferroelectric behaviors and switching properties of Al:Hf0.5Zr0.5O2 (Al:HZO) films. Our study employed a Pt/Al:Hf0.5Zr0.5O2/Si structure to form two interfaces with different interfacial oxygen defects. Oxygen vacancies were mainly accumulated at the HZO/Si interface, confirmed by the XPS results. By carefully examining the P–V loops, C–V loops, and the corresponding switching current loops, we found that the domains were clearly divided into two parts, which resulted in the slit-up of the switching current peaks and distorted P–V loops. Further cycling results showed that the wake-up performances had arisen from the biased domains. We further simulated the switching dynamics by using the nucleation limited switching model. Distorted switching kinetics and unsatisfied switching polarization were observed for the initial samples, while the switching dynamics showed the same tendency after waking up. The results elucidate that the influence of interfacial oxygen vacancies is mainly to induce the built-in field at the interface, which may be helpful for the understanding of the switching behaviors of HfO2-based ferroelectric films.