Effects of cation-substitution on the ferroelectric properties of sol-gel derived PZT thin film for FRAM application

Woo Sik Kim, Soon Mok Ha, Hyung-Ho Park, Chang Eun Kim

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26 Citations (Scopus)

Abstract

Cation-substituted PZT thin films are more desirable for ferroelectric memory applications due to their lower coercive field, higher resistivity and lower dielectric memory-aging rate compared to PZT thin films. The resulting effect of cation-substitution can be explained on the basis of defect chemistry in a perovskite lattice. In this study, La and Nb were chosen as substituents and their effects on fatigue behavior and leakage properties of PZT-base thin films were investigated. La- or Nb-substituted PZT thin films were deposited by the sol-gel processing method on Pt electrode. The Zr/Ti ratio was fixed as 40/60 with the tetragonal perovskite phase. The excess Pb added onto the starting precursor was fixed to 15 wt.%. Each sol-gel process condition and heating process were optimized based upon its thermal analysis result. The surface microstructure, crystallinity, ferroelectric properties, and leakage characteristics were investigated. It is shown through C-V and I-V characteristics that both A-site (La) and B- site (Nb) substituent play a role in development of electrical properties. However, cation substitution induces lattice site defect to maintain a charge neutrality. In case of Nb, Pb-deficient pyrochlore phase was formed due to A-site vacancies (Pb vacancies). PNZT films showed the degradation of ferroelectric properties.

Original languageEnglish
Pages (from-to)531-535
Number of pages5
JournalThin Solid Films
Volume355
DOIs
Publication statusPublished - 1999 Nov 1
EventProceedings of the 1999 26th International Conference on Metallurgic Coatings and Thin Films - San Diego, CA, USA
Duration: 1999 Apr 121999 Apr 15

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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