Switchable diode-effect mechanism in ferroelectric BiFeO3 thin film capacitors

We investigate the mechanism of a switchable diode behavior observed in ferroelectric SrRuO3/BiFeO3 (BFO)/SrRuO3 capacitors. We experimentally demonstrate that the switchable diode effect observed in the capacitors is induced by the polarization reversal in the BFO film. The conductivity in an Ohmic...

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Bibliographic Details
Published in:Journal of applied physics 2015-09, Vol.118 (11)
Main Authors: Matsuo, Hiroki, Kitanaka, Yuuki, Inoue, Ryotaro, Noguchi, Yuji, Miyayama, Masaru
Format: Article
Language:English
Subjects:
Applied physics
Bismuth ferrite
Capacitors
Carrier density
Density functional theory
Ferroelectric materials
Ferroelectricity
Holes (electron deficiencies)
Majority carriers
Oxidation
Polarization
Thin films
Vacancies
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Summary:We investigate the mechanism of a switchable diode behavior observed in ferroelectric SrRuO3/BiFeO3 (BFO)/SrRuO3 capacitors. We experimentally demonstrate that the switchable diode effect observed in the capacitors is induced by the polarization reversal in the BFO film. The conductivity in an Ohmic region in different oxidation states provides direct evidence that electron hole acts as the majority carrier, delivering p-type conduction. Density functional theory (DFT) calculations show that the p-type conduction arises from an unoccupied gap state of Fe4+ in an FeO5 pyramid which is derived from Bi vacancy. Our experimental and DFT study leads to the conclusion that the switchable diode effect originates from an asymmetric band bending in the top and bottom depletion layers modulated by ferroelectric polarization and oxygen vacancies.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4930590