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

Ferroelectric HfO2 epitaxial films are of interest for determining intrinsic properties and for prototyping devices. Epitaxial (111)-oriented orthorhombic Hf0.5Zr0.5O2 films grown on La0.67Sr0.33MnO3/SrTiO3(001) are already being actively investigated. Now, we have explored the use of SrTiO3(111) substrates. We show that the orthorhombic phase is stabilized by tilted epitaxy, and the orientation of the 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 ferroelectric phase in the film, and the predicted polarization of ferroelectric HfO2. High endurance and retention are also measured.Financial support from the Spanish Ministry of Science and Innovation (MCIN/AEI/ 10.13039/501100011033), through the Severo Ochoa FUNFUTURE (CEX2019-000917-S), PID2020- 112548RB-I00 and PID2019-107727RB-I00 projects, from CSIC through the i-LINK (LINKA20338) program, and from Generalitat de Catalunya (2017 SGR 1377) is acknowledged. Project supported by a 2020 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. IF acknowledges Ramón y Cajal contract RYC-2017-22531. TS is financially supported by China Scholarship Council (CSC) with No. 201807000104. TS work has been done as a part of his Ph.D. program in Materials Science at Universitat Autònoma de Barcelona. SE acknowledges the Spanish Ministry of Science and Innovation for his PhD contract (SEV-2015-0496-16-3) and its cofunding by the ESF. ICTS-CNME at UCM is acknowledged for offering access to STEM microscopy and expertise.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe