Origin of Ferroelectricity in Epitaxial Si-Doped HfO 2 Films

Tao Li, Mao Ye, Zhenzhong Sun, Nian Zhang, Wei Zhang, Saikumar Inguva, Chunxiao Xie, Lang Chen, Yu Wang, Shanming Ke, Haitao Huang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

21 Citations (Scopus)

Abstract

HfO 2 -based unconventional ferroelectric materials were recently discovered and have attracted a great deal of attention in both academia and industry. The growth of epitaxial Si-doped HfO 2 films has opened up a route to understand the mechanism of ferroelectricity. Here, we used pulsed laser deposition to grow epitaxial Si-doped HfO 2 films in different orientations of N-type SrTiO 3 substrates. Polar nanodomains can be written and read using piezoforce microscopy, and these domains are reversibly switched with a phase change of 180°. Films with different thicknesses displayed a coercive field E c and a remnant polarization P r of approximately 4-5 MV/cm and 8-32 μC/cm 2 , respectively. X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) results identified that the as-grown Si-doped HfO 2 films have strained fluorite structures. The ABAB stacking mode of the Hf atomic grid observed by HRTEM clearly demonstrates that the ferroelectricity originates from the noncentrosymmetric Pca2 1 polar structure. Combined with soft X-ray absorption spectra, the results showed that the Pca2 1 ferroelectric crystal structure manifested as an O sublattice distortion by the effect of the interface strain and Si dopant interactions, resulting in a nanoscaled ferroelectric ordered state because of further crystal splitting.

Original languageEnglish
Pages (from-to)4139-4144
Number of pages6
JournalACS Applied Materials and Interfaces
Volume11
Issue number4
DOIs
Publication statusPublished - 30 Jan 2019

Keywords

  • epitaxial Si-doped HfO thin films
  • ferroelectricity
  • HRTEM
  • N-type SrTiO substrates
  • PFM
  • PLD
  • XAS
  • XRD

ASJC Scopus subject areas

  • Materials Science(all)

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