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Effects of Interfacial States on Asymmetric Polarization Switchings of Epitaxial Bi4Ti3012 Thin Films

Published online by Cambridge University Press:  15 February 2011

Bae-Ho Park
Affiliation:
Department of Physics, Seoul National University, Seoul 151–742, Korea
Sang-Jin Hyun
Affiliation:
Department of Physics, Seoul National University, Seoul 151–742, Korea
S. H. Mun
Affiliation:
Department of Physics, Seoul National University, Seoul 151–742, Korea
T. W. Noh
Affiliation:
Department of Physics, Seoul National University, Seoul 151–742, Korea
J. Lee
Affiliation:
Department of Materials Engineering, Sung Kyun Kwan University, Suwon 440–746, Korea
See-Hyung Lee
Affiliation:
LG Corporate Institute of Technology, Seocho-gu, Seoul 137–140, Korea
W. Jo
Affiliation:
LG Corporate Institute of Technology, Seocho-gu, Seoul 137–140, Korea
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Abstract

Epitaxial Bi4Ti3012 (BTO) films with Lao0.5Sr0.5Co03 (LSCO) or Pt bottom electrodes were grown on MgO(OOl) substrates by pulsed laser deposition. Surprisingly, a symmetric Pt/BTO/Pt capacitor showed a highly asymmetric polarization switching and an asymmetric Pt/BTO/LSCO capacitor revealed a nearly symmetric polarization switching. To understand these intriguing phenomena, Auger electron spectroscopy and x-ray photoemission spectroscopy depth-profiles were used. The evidences for interdiffusions at the bottom BTO/Pt interface were found. To get further understanding on the interfacial states, a capacitance-voltage (C-V) measurement was performed on the Pt/BTO/Pt capacitor. By fitting the C-V data with a back-to-back Schottky diode model, built-in voltages at the top and the bottom interfaces were determined to be 1.1 V and 3.2 V, respectively. From the obtained built-in voltages, an asymmetric band diagram for the Pt/BTO/Pt structure was suggested. Therefore, the imprint failure can be explained by existence of asymmetric interracial states.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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