First-Principles Perspective on Poling Mechanisms and Ferroelectric/Antiferroelectric Behavior of Hf1-xZrxO2 for FEFET Applications

摘要

We investigate at the atomic level the most probable phase transformations under strain, that are responsible for the ferroelectric/antiferroelectric behavior in Hf_1-xZr_xO₂ materials. Four different crystalline phase transformations exhibit a polar/non-polar transition: monoclinic-to-orthorhombic requires a gliding strain tensor, orthorhombic-to-orthorhombic transformation does not need strain to polarize the material, whereas tetragonal-to-cubic cell compression and tetragonal-to-orthorhombic cell elongation destabilizes the non-polar tetragonal phase, facilitating the transition towards a polar atomic configuration, therefore changing the polarization-electric field loop from antiferroelectric to ferroelectric. Oxygen vacancies can reduce drastically the polarization reversal barriers.