Improved polarization and endurance in ferroelectric Hf0.5Zr0.5O2 films on SrTiO3(110)

Abstract

The metastable orthorhombic phase of Hf0.5Zr0.5O2 (HZO) can be stabilized in thin films on La0.67Sr0.33MnO3 (LSMO) buffered (001)-oriented SrTiO3 (STO) by an intriguing epitaxy that results in (111)-HZO oriented growth and robust ferroelectric properties. Here, we shown that the orthorhombic phase can also be epitaxially stabilized on LSMO/STO(110), presenting the same out-of-plane (111) orientation but a different distribution of in-plane crystalline domains. The remanent polarization of HZO films with a thickness of less than 7 nm on LSMO/STO(110) is 33 µC cm-2, which corresponds to a 50% improvement over equivalent films on LSMO/STO(001). Furthermore, HZO on LSMO/STO(110) presents higher endurance, switchable polarization is still observed up to 4x1010 cycles, and retention of more than 10 years. These results demonstrate that tuning epitaxial growth of ferroelectric HfO2, here by using STO(110) substrates, allows improving functional properties of relevance for memory applications.