DOI: 10.1021/acsami.8b18762

Epitaxial ferroelectric Hf_0.5Zr_0.5O₂ films have been successfully integrated in a capacitor heterostructure on Si(001). The orthorhombic Hf_0.5Zr_0.5O₂ phase, [111] out-of-plane oriented, is stabilized in the films. The films present high remnant polarization Pr close to 20 μC/cm2, rivaling with equivalent epitaxial films on single crystalline oxide substrates. Retention time is longer than 10 years for writing field of around 5 MV/cm, and the capacitors show endurance up to 10⁹ cycles for writing voltage of around 4 MV/cm. It is found that the formation of the orthorhombic ferroelectric phase depends critically on the bottom electrode, being achieved on La_0.67Sr_0.33MnO₃ but not on LaNiO₃. The demonstration of excellent ferroelectric properties in epitaxial films of Hf_0.5Zr_0.5O₂ on Si(001) is relevant towards fabrication of devices that require homogeneity in the nanometer scale, as well as for better understanding of the intrinsic properties of this promising ferroelectric oxide.