Ferroelectrics everywhere: Ferroelectricity in magnesium substituted zinc oxide thin films

We demonstrate ferroelectricity in Mg-substituted ZnO thin films with the wurtzite structure. Zn1−xMgxO films are grown by dual-cathode reactive magnetron sputtering on (111)-Pt // (0001)-Al2O3 substrates at temperatures ranging from 26 to 200 °C for compositions spanning from x = 0 to x = 0.37. X-ray diffraction indicates a decrease in the c-lattice parameter and an increase in the a-lattice parameter with increasing Mg content, resulting in a nearly constant c/a axial ratio of 1.595 over this composition range. Transmission electron microscopy studies show abrupt interfaces between Zn1−xMgxO films and the Pt electrode. When prepared at pO2 = 0.025, film surfaces are populated by abnormally oriented grains as measured by atomic force microscopy for Mg concentrations >29%. Raising pO2 to 0.25 eliminates the misoriented grains. Optical measurements show increasing bandgap values with increasing Mg content. When prepared on a 200 °C substrate, films display ferroelectric switching with remanent polarizations exceeding 100 μC cm−2 and coercive fields below 3 MV cm−1 when the Mg content is between ∼30% and ∼37%. Substrate temperature can be lowered to ambient conditions, and when doing so, capacitor stacks show only minor sacrifices to crystal orientation and nearly identical remanent polarization values; however, coercive fields drop below 2 MV/cm. Using ambient temperature deposition, we demonstrate ferroelectric capacitor stacks integrated directly with polymer substrate surfaces.



Work Title Ferroelectrics everywhere: Ferroelectricity in magnesium substituted zinc oxide thin films
Open Access
  1. Kevin Ferri
  2. Saiphaneendra Bachu
  3. Wanlin Zhu
  4. Mario Imperatore
  5. John Hayden
  6. Nasim Alem
  7. Noel Giebink
  8. Susan E. Trolier-McKinstry
  9. Jon-Paul Maria
License In Copyright (Rights Reserved)
Work Type Article
  1. Journal of Applied Physics
Publication Date July 28, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1063/5.0053755
Deposited December 08, 2021




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Work History

Version 1

  • Created
  • Added Ferroelectrics_Everywhere_-_Ferroelectrticity_in_Magnesium_Substituted_Zinc_Oxide_Thin_Films-JAP-2021.pdf
  • Added Creator Kevin Ferri
  • Added Creator Saiphaneendra Bachu
  • Added Creator Wanlin Zhu
  • Added Creator Mario Imperatore
  • Added Creator John Hayden
  • Added Creator Nasim Alem
  • Added Creator Noel Giebink
  • Added Creator Susan E. Trolier-McKinstry
  • Added Creator Jon-Paul Maria
  • Published
  • Updated
  • Updated