Ferroelectric Hf0.5Zr0.5O2 films on SrTiO3(111)

Abstract

Ferroelectric HfO₂ epitaxial films are of interest for determining intrinsic properties and for prototyping devices. Epitaxial (111)-oriented orthorhombic Hf_0.5Zr_0.5O₂ films grown on La_0.67Sr_0.33MnO₃/SrTiO₃(001) are already being actively investigated. Presently, we have explored the use of SrTiO₃(111) substrates. We show that the orthorhombic phase is stabilized by tilted epitaxy, and the orientation of orthorhombic crystallites is different from that of equivalent films on SrTiO₃(001). The measured remanent polarization of above 14 μC cm⁻² agrees well with the expected value considering the crystal orientation, the fraction of the ferroelectric phase in the film, and the predicted polarization for ferroelectric HfO₂. High endurance and retention are also measured.