Stress engineering in ferroelectric hafnium oxide for tuning epitaxial orientation

The development of next generation computing paradigms and memory devices relies on exploiting the unique properties of ferroelectric materials. Hafnium oxide-based ferroelectrics, which are highly compatible with semiconductor processing, offer a promising alternative to conventional perovskite ferroelectrics that face integration challenges. However, the enhancement of ferroelectricity in hafnium oxide and its dependence on epitaxial growth orientation remain insufficiently explored. In this study, we demonstrate that the epitaxial orientation of hafnium oxide is strongly correlated with the in-plane strain conditions. Depending on the strain state, the HfO2 film exhibits either (002)- or (111)-oriented epitaxial growth. Notably, the (002)-oriented films exhibit enhanced ferroelectric polarization. These findings provide an effective strategy for achieving controllable epitaxial growth of ferroelectric HfO2 and for further improving its ferroelectric performance in practical applications.