On the Importance of the Work Function and Electron Carrier Density of Oxide Electrodes for the Functional Properties of Ferroelectric Capacitors

Jun Wang, Minh Duc Nguyen, Nicolas Gauquelin, Johan Verbeeck, Minh Thanh Do, Gertjan Koster, Guus Rijnders, Evert Houwman*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)
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Abstract

It is important to understand the effect of the interfaces between the oxide electrode layers and the ferroelectric layer on the polarization response for optimizing the device performance of all-oxide ferroelectric devices. Herein, the effects of the oxide La0.07Ba0.93SnO3 (LBSO) as an electrode material in an PbZr0.52Ti0.48O3 (PZT) ferroelectric capacitor are compared with those of the more commonly used SrRuO3 (SRO) electrode. SRO (top)/PZT/SRO (bottom), SRO/PZT/LBSO, and SRO/PZT/2 nm SRO/LBSO devices are fabricated. Only marginal differences in crystalline properties, determined by X-ray diffraction and scanning transmission electron microscopy, are found. High-quality polarization loops are obtained, but with a much larger coercive field for the SRO/PZT/LBSO device. In contrast to the SRO/PZT/SRO device, the polarization decreases strongly with increasing field cycling. This fatigue problem can be remedied by inserting a 2 nm SRO layer between PZT and LBSO. It is argued that strongly increased charge injection into the PZT occurs at the bottom interface, because of the low PZT/LBSO interfacial barrier and the much lower carrier density in LBSO, as compared with that in SRO, causing a low dielectric constant, depleted layer in LBSO. The charge injection creates a trapped space charge in the PZT, causing the difference in fatigue behavior.

Original languageEnglish
Article number1900520
JournalPhysica Status Solidi - Rapid Research Letters
Volume14
Issue number3
Early online date12 Dec 2019
DOIs
Publication statusPublished - 1 Mar 2020

Keywords

  • UT-Hybrid-D
  • La-doped BaSnO
  • oxide thin films
  • Pb(Zr,Ti)O
  • ferroelectric capacitors

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