Ferroelectricity in Rare-Earth Modified Hafnia Thin Films Deposited by Sequential Pulsed Laser Deposition

摘要

Room temperature ferroelectricity in pulsed laser deposited rare-earth doped hafnium oxide (HfO2) thin films is discussed. Maximum values of remnant polarizations (P-r) similar to 13.5 and 12 mu C/cm(2) along with coercive fields (E-C) similar to 334 and 384 kV/cm are observed in 6 mol. % of rare-earth (Sm or Gd) doped-HfO2 thin films (Sm:HfO2 and Gd:HfO2), respectively. Piezoresponse force microscopy measurements confirmed ferroelectric nature of films by showing phase hysteresis and butterfly amplitude loops. It is noticed that wake-up cycles improved the remnant polarization and found to be necessary for the forming of well saturated hysteresis loops. Our results showed potential toward realization of future highly scaled non-volatile ferroelectric memories. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.