Infrared Signatures for Phase Identification in Hafnium Oxide Thin Films

Samantha T. Jaszewski, Sebastian Calderon, Bishal Shrestha, Shelby S. Fields, Atanu Samanta, Fernando J. Vega, Jacob D. Minyard, Joseph A. Casamento, Jon Paul Maria, Nikolas J. Podraza, Elizabeth C. Dickey, Andrew M. Rappe, Thomas E. Beechem, Jon F. Ihlefeld

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Phase identification in HfO2-based thin films is a prerequisite to understanding the mechanisms stabilizing the ferroelectric phase in these materials, which hold great promise in next-generation nonvolatile memory and computing technology. While grazing-incidence X-ray diffraction is commonly employed for this purpose, it has difficulty unambiguously differentiating between the ferroelectric phase and other metastable phases that may exist due to similarities in the d-spacings, their low intensities, and the overlapping of reflections. Infrared signatures provide an alternative route. However, their use in phase identification remains limited because phase control has overwhelmingly been accomplished via substituents, thereby convoluting infrared signatures between the substituents and the phase changes that they induce. Herein, we report the infrared optical responses of three undoped hafnium oxide films where annealing conditions have been used to create films consisting primarily of the ferroelectric polar orthorhombic Pca21, antipolar orthorhombic Pbca, and monoclinic P21/c phases, as was confirmed via transmission electron microscopy (TEM), UV-visible optical properties, and electrical property measurements. Vibrational signatures acquired from synchrotron nano-Fourier transform infrared spectroscopy (nano-FTIR) are shown to be capable of differentiating between the phases in a nondestructive, rapid, and nanoscale manner. The utility of nano-FTIR is illustrated for a film exhibiting an antiferroelectric polarization response. In this sample, it is proven that this behavior results from the Pbca phase rather than the often-cited tetragonal phase. By demonstrating that IR spectroscopy can unambiguously distinguish phases in this material, this work establishes a tool needed to isolate the factors dictating the ferroelectric phase stability in HfO2-based materials.

Original languageEnglish
Pages (from-to)23944-23954
Number of pages11
JournalACS Nano
Issue number23
StatePublished - 12 Dec 2023
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2023 American Chemical Society.


Thin film synthesis and X-ray diffraction characterization were supported by the Semiconductor Research Corporation (SRC) within the Nanomanufacturing, Materials, and Processes (NMP) Program under task 2875.001. S.T.J. acknowledges support from the U.S. National Science Foundation’s Graduate Research Fellowship Program under Grant DGE-1842490. Nano-FTIR, electrical characterization, electron microscopy, X-ray photoelectron spectroscopy, and computation were supported by the Center for 3D Ferroelectric Microelectronics (3DFeM), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0021118. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231. Computational support was provided by the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy, Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under Contract DE-NA0003525. The authors acknowledge beamline scientists Hans Bechtel and Stephanie Gilbert Corder for their technical assistance in nano-FTIR measurements. The authors acknowledge use of the Materials Characterization Facility at Carnegie Mellon University supported by Grant MCF-677785. The authors acknowledge the Pennsylvania State University Materials Characterization Lab for use of the XPS instrument. Special thanks to Sobhit Singh of University of Rochester for providing phonon mode energy data from his past work.

FundersFunder number
Center for 3D Ferroelectric Microelectronics
National Science FoundationDGE-1842490
U.S. Department of Energy
Semiconductor Research Corporation
Office of ScienceDE-AC02-05CH11231
Basic Energy SciencesDE-SC0021118
National Nuclear Security AdministrationDE-NA0003525, MCF-677785
Sandia National Laboratories
Lawrence Berkeley National Laboratory
Laboratory Directed Research and Development
National Energy Research Scientific Computing Center


    • Ferroelectric
    • Hafnium Oxide
    • Infrared Spectroscopy
    • Phases
    • Transmission Electron Microscopy


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