Epitaxial Integration on Si(001) of Ferroelectric Hf0.5Zr0.5O₂ Capacitors with High Retention and Endurance

Epitaxial ferroelectric Hf 0.5 Zr 0.5 O 2 films have been successfully integrated in a capacitor heterostructure on Si(001). The orthorhombic Hf 0.5 Zr 0.5 O 2 phase, [111] out-of-plane oriented, is stabilized in the films. The films present high remnant polarization P r close to 20 μC/cm 2, rivaling with equivalent epitaxial films on single crystalline oxide substrates. Retention time is longer than 10 years for a writing field of around 5 MV/cm, and the capacitors show endurance up to 10 9 cycles for a 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 0.67 Sr 0.33 MnO 3 but not on LaNiO 3 . The demonstration of excellent ferroelectric properties in epitaxial films of Hf 0.5 Zr 0.5 O 2 on Si(001) is relevant toward 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.