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Title: Ferroelectric interaction and polarization studies in BaTiO{sub 3}/SrTiO{sub 3} superlattice

Abstract

Ferroelectric superlattice structures consisting of alternating layers of BaTiO{sub 3} and SrTiO{sub 3} with variable interlayer thickness were grown on Pt (111)/TiO{sub 2}/SiO{sub 2}/Si (100) substrates by pulsed laser deposition. The presence of superlattice reflections in the x-ray diffraction pattern clearly showed the superlattice behavior of the fabricated structures over a range of 6.4-20 nm individual layer thicknesses. Depth profile conducted by secondary ion mass spectrometry analysis showed a periodic concentration of Ba and Sr throughout the film. Polarization hysteresis and the capacitance-voltage characteristics of these films show clear size dependent ferroelectric characteristics. The spontaneous (P{sub s}) and remnant (P{sub r}) polarizations increase gradually with decreasing periodicity, reach a maximum at a finite thickness and then decrease. The competition between the size effect and long-range ferroelectric interaction is suggested as a possible reason for this phenomenon. The temperature dependence of P{sub s} and P{sub r} shows a single ferroelectric phase transition, and the Curie temperature is estimated to be about 316 K. The curve shows that the ferroelectric superlattice tends to form an artificial material, responding as a single structure with an averaged behavior of both the parent systems.

Authors:
;  [1]
  1. Materials Research Center, Indian Institute of Science, Bangalore 560 012 (India)
Publication Date:
OSTI Identifier:
20982900
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 10; Other Information: DOI: 10.1063/1.2724822; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BARIUM COMPOUNDS; CAPACITANCE; CURIE POINT; ELECTRIC POTENTIAL; ENERGY BEAM DEPOSITION; FERROELECTRIC MATERIALS; LASER RADIATION; MASS SPECTRA; MASS SPECTROSCOPY; PHASE TRANSFORMATIONS; PLATINUM; PULSED IRRADIATION; SILICON OXIDES; STRONTIUM TITANATES; SUPERLATTICES; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; TITANIUM OXIDES; X-RAY DIFFRACTION

Citation Formats

Sarkar, Asis, and Krupanidhi, S. B.. Ferroelectric interaction and polarization studies in BaTiO{sub 3}/SrTiO{sub 3} superlattice. United States: N. p., 2007. Web. doi:10.1063/1.2724822.
Sarkar, Asis, & Krupanidhi, S. B.. Ferroelectric interaction and polarization studies in BaTiO{sub 3}/SrTiO{sub 3} superlattice. United States. doi:10.1063/1.2724822.
Sarkar, Asis, and Krupanidhi, S. B.. Tue . "Ferroelectric interaction and polarization studies in BaTiO{sub 3}/SrTiO{sub 3} superlattice". United States. doi:10.1063/1.2724822.
@article{osti_20982900,
title = {Ferroelectric interaction and polarization studies in BaTiO{sub 3}/SrTiO{sub 3} superlattice},
author = {Sarkar, Asis and Krupanidhi, S. B.},
abstractNote = {Ferroelectric superlattice structures consisting of alternating layers of BaTiO{sub 3} and SrTiO{sub 3} with variable interlayer thickness were grown on Pt (111)/TiO{sub 2}/SiO{sub 2}/Si (100) substrates by pulsed laser deposition. The presence of superlattice reflections in the x-ray diffraction pattern clearly showed the superlattice behavior of the fabricated structures over a range of 6.4-20 nm individual layer thicknesses. Depth profile conducted by secondary ion mass spectrometry analysis showed a periodic concentration of Ba and Sr throughout the film. Polarization hysteresis and the capacitance-voltage characteristics of these films show clear size dependent ferroelectric characteristics. The spontaneous (P{sub s}) and remnant (P{sub r}) polarizations increase gradually with decreasing periodicity, reach a maximum at a finite thickness and then decrease. The competition between the size effect and long-range ferroelectric interaction is suggested as a possible reason for this phenomenon. The temperature dependence of P{sub s} and P{sub r} shows a single ferroelectric phase transition, and the Curie temperature is estimated to be about 316 K. The curve shows that the ferroelectric superlattice tends to form an artificial material, responding as a single structure with an averaged behavior of both the parent systems.},
doi = {10.1063/1.2724822},
journal = {Journal of Applied Physics},
number = 10,
volume = 101,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • We investigated infrared-active phonons of CaTiO3, SrTiO3, BaTiO3, and Ba0.5Sr0.5TiO3 thin films, and a (BaTiO3)5/(SrTiO3)5 artificial superlattice by a Fourier transform infrared spectrometer with a grazing angle (48{sup o}) incident reflectance method. The longitudinal phonon energies of the thin films were different from those of the bulk material due to the lattice strain of the substrate. The Ba0.5Sr0.5TiO3 thin film and (BaTiO3)5/(SrTiO3)5 superlattice showed different phonon modes due to structural discrepancies, even though their chemical compositions are similar. The Ba0.5Sr0.5TiO3 thin film showed a single phonon energy lying between the phonon energies of BaTiO3 and SrTiO3 thin films, while themore » (BaTiO3)5/(SrTiO3)5 superlattice well preserved the characteristic phonon modes of BaTiO3 and SrTiO3 thin films.« less
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  • The integration of functional oxide thin-films on compound semiconductors can lead to a class of reconfigurable spin-based optoelectronic devices if defect-free, fully reversible active layers are stabilized. However, previous first-principles calculations predicted that SrTiO 3 thin filmsgrown on Si exhibit pinned ferroelectric behavior that is not switchable, due to the presence of interfacial vacancies. Meanwhile, piezoresponse force microscopy measurements have demonstrated ferroelectricity in BaTiO 3 grown on semiconductor substrates. The presence of interfacial oxygen vacancies in such complex-oxide/semiconductor systems remains unexplored, and their effect on ferroelectricity is controversial. Here, we use a combination of aberration-corrected scanning transmission electron microscopy andmore » first-principles density functional theory modeling to examine the role of interfacial oxygen vacancies on the ferroelectricpolarization of a BaTiO 3 thin filmgrown on GaAs. Here, we demonstrate that interfacial oxygen vacancies enhance the polar discontinuity (and thus the single domain, out-of-plane polarization pinning in BaTiO 3), and propose that the presence of surface charge screening allows the formation of switchable domains.« less
  • The integration of functional oxide thin-films on compound semiconductors can lead to a class of reconfigurable spin-based optoelectronic devices if defect-free, fully reversible active layers are stabilized. However, previous first-principles calculations predicted that SrTiO{sub 3} thin films grown on Si exhibit pinned ferroelectric behavior that is not switchable, due to the presence of interfacial vacancies. Meanwhile, piezoresponse force microscopy measurements have demonstrated ferroelectricity in BaTiO{sub 3} grown on semiconductor substrates. The presence of interfacial oxygen vacancies in such complex-oxide/semiconductor systems remains unexplored, and their effect on ferroelectricity is controversial. Here, we use a combination of aberration-corrected scanning transmission electron microscopymore » and first-principles density functional theory modeling to examine the role of interfacial oxygen vacancies on the ferroelectric polarization of a BaTiO{sub 3} thin film grown on GaAs. We demonstrate that interfacial oxygen vacancies enhance the polar discontinuity (and thus the single domain, out-of-plane polarization pinning in BaTiO{sub 3}), and propose that the presence of surface charge screening allows the formation of switchable domains.« less