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Journal of Materials Science

, Volume 49, Issue 9, pp 3337–3351 | Cite as

Schottky barrier versus surface ferroelectric depolarization at Cu/Pb(Zr, Ti)O3 interfaces

  • Laura E. Stoflea
  • Nicoleta G. Apostol
  • Cristina Chirila
  • Lucian Trupina
  • Raluca Negrea
  • Lucian Pintilie
  • Cristian M. Teodorescu
Article

Abstract

The band bending at Cu/PZT(001) interfaces is investigated by X-ray photoelectron spectroscopy (XPS) for a PZT(001) layer which exhibits initial outwards ferroelectric polarization. Two competitive processes are identified: (a) formation of the Schottky barrier between the ferroelectric and unconnected Cu islands, and (b) coalescence of the Cu islands, realisation of an electrical contact to the ground of the system, inducing the apparent loss of the component of the ferroelectric polarization perpendicular to the sample surface, at least as it manifests in band bending. Three mechanisms are proposed to explain this loss of band bending when a full metal layer connected to ground is formed on the surface: (i) over-compensation of depolarization field in the sub-surface region, (ii) formation of domains with in-plane orientation of the polarization vector and (iii) loss of polarization in the near-surface layers of the ferroelectric due to electrons provided by the metal. These result in a non-monotonous variation of binding energies with the amount of Cu deposited. High resolution transmission electron microscopy and piezoresponse force microscopy confirmed these hypotheses. The XPS data allowed also to derive the surface PZT composition, its evolution with the deposition of copper and the formation of surface compounds.

Keywords

Schottky Barrier Schottky Diode Ferroelectric Polarization Piezoresponse Force Microscopy Valence Band Spectrum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

This work is supported by the UEFISCDI Contract PCCE No. 3/2011 granted by the Romanian Ministry of Education. We acknowledge the valuable help of Iuliana Pasuk with the X-ray diffraction data.

Supplementary material

10853_2014_8041_MOESM1_ESM.pdf (264 kb)
Supplementary material 1 (PDF 264 kb)

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Laura E. Stoflea
    • 1
  • Nicoleta G. Apostol
    • 1
  • Cristina Chirila
    • 1
  • Lucian Trupina
    • 1
  • Raluca Negrea
    • 1
  • Lucian Pintilie
    • 1
  • Cristian M. Teodorescu
    • 1
  1. 1.National Institute of Materials Physics Bucharest-MagureleMagurele-IlfovRomania

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