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Title: Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method

Abstract

We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO{sub 3} (111) substrates and the deposition of ferroelectric BiFeO{sub 3} thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO{sub 3}){sup 4−} or Ti{sup 4+} layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d{sub 111}) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO{sub 3} single crystal substrates. Multiferroic BiFeO{sub 3} thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO{sub 3} (111) substrates. Bi(NO{sub 3}){sub 3} and Fe(NO{sub 3}){sub 3} along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO{sub 3} films on Nb : SrTiO{sub 3} (100) substrates was verified by piezoresponse force microscopy.

Authors:
; ; ; ;  [1]
  1. Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec, J3X1S2 (Canada)
Publication Date:
OSTI Identifier:
22611537
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BISMUTH COMPOUNDS; BISMUTH NITRATES; DOPED MATERIALS; FERRITES; FERROELECTRIC MATERIALS; HYDROTHERMAL SYNTHESIS; IRON NITRATES; LAYERS; MICROSCOPY; MICROWAVE RADIATION; MONOCRYSTALS; NIOBIUM ADDITIONS; NITROGEN OXIDES; POTASSIUM HYDROXIDES; STRONTIUM OXIDES; STRONTIUM TITANATES; SUBSTRATES; SURFACES; THIN FILMS; TITANIUM IONS

Citation Formats

Velasco-Davalos, Ivan, Ambriz-Vargas, Fabian, Kolhatkar, Gitanjali, Thomas, Reji, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca, and Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca. Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method. United States: N. p., 2016. Web. doi:10.1063/1.4954695.
Velasco-Davalos, Ivan, Ambriz-Vargas, Fabian, Kolhatkar, Gitanjali, Thomas, Reji, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca, & Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca. Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method. United States. doi:10.1063/1.4954695.
Velasco-Davalos, Ivan, Ambriz-Vargas, Fabian, Kolhatkar, Gitanjali, Thomas, Reji, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca, and Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca. Wed . "Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method". United States. doi:10.1063/1.4954695.
@article{osti_22611537,
title = {Synthesis of BiFeO{sub 3} thin films on single-terminated Nb : SrTiO{sub 3} (111) substrates by intermittent microwave assisted hydrothermal method},
author = {Velasco-Davalos, Ivan and Ambriz-Vargas, Fabian and Kolhatkar, Gitanjali and Thomas, Reji, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca and Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca, E-mail: reji.thomas@emt.inrs.ca},
abstractNote = {We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO{sub 3} (111) substrates and the deposition of ferroelectric BiFeO{sub 3} thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO{sub 3}){sup 4−} or Ti{sup 4+} layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d{sub 111}) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO{sub 3} single crystal substrates. Multiferroic BiFeO{sub 3} thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO{sub 3} (111) substrates. Bi(NO{sub 3}){sub 3} and Fe(NO{sub 3}){sub 3} along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO{sub 3} films on Nb : SrTiO{sub 3} (100) substrates was verified by piezoresponse force microscopy.},
doi = {10.1063/1.4954695},
journal = {AIP Advances},
number = 6,
volume = 6,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}
  • The multiferroic properties of BiFeO{sub 3}-CoFe{sub 2}O{sub 4} (BFO-CFO) heterostructures thin film grown on (111) SrTiO{sub 3} (STO) substrates by employing pulsed laser deposition (PLD) method, have been studied.X ray diffraction analysis reveals the presence of BFO and CFO in two separate phases. The heterostructures BFO/CFO/STO(111) thin films show well – shaped hysteresis loop with saturated magnetization and coercive field, which are much larger than pure BFO/STO thin film. The frequency dependent dielectric anomalies in BFO-CFO multilayer are attributed to the interfacial effect across the presence of CFO as a separate phase embedded in BFO matrix.
  • The integration of oxides with semiconductors is important for the technological advancement of the next generation electronics. Concomitant ferroelectric and antiferromagnetic (AF) behavior is demonstrated in single crystal BiFeO{sub 3} (BFO) films grown on 20 nm SrTiO{sub 3} (STO) virtual substrates on Si(100) using molecular beam epitaxy (MBE). STO thin films are grown in an oxide MBE chamber by co-deposition of Sr, Ti, and molecular O{sub 2}. Careful control of the O{sub 2} during nucleation produced commensurate growth of STO on Si. The sequence of the steps allows for the suppression of an amorphous SiO{sub 2} layer. This STO(20 nm)/Simore » structure was used as a virtual substrate for MBE deposition of BFO on Si without breaking vacuum. BFO was deposited using Fe and O{sub 2} plasma with an overpressure of Bi flux, the growth rate was controlled by the incoming Fe flux. The reflection high energy electron diffraction image shows a 2-D growth front with a 6-fold surface reconstruction under optimized O{sub 2} pressure of 5 Multiplication-Sign 10{sup -8} mbar. Cross-sectional transmission electron microscopy (TEM) confirms the high crystallinity of the films and shows sharp, atomically flat interfaces. The selected area diffraction pattern (SADP) reveals that BFO grows in a distorted rhombohedral crystal structure. X-ray diffraction does not show formation of second phases and is consistent with the TEM and SADP results. The BFO films show AF behavior with a Neel temperature that exceeds 350 K, as expected (T{sub N} = 673 K) and with a residual ferromagnetic behavior that decreases with film thickness and is consistent with the G-type AF due to the canted spins. The saturation magnetization per unit volume for a 40 nm thick film was 180 emu/cm{sup 3} at an in-plane magnetic field of 8 kOe. The ferroelectric behavior of the films was verified using piezoresponse force microscopy.« less
  • 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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