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Title: Induced polarized state in intentionally grown oxygen deficient KTaO{sub 3} thin films

Deliberately oxygen deficient potassium tantalate thin films were grown by RF magnetron sputtering on Si/SiO{sub 2}/Ti/Pt substrates. Once they were structurally characterized, the effect of oxygen vacancies on their electric properties was addressed by measuring leakage currents, dielectric constant, electric polarization, and thermally stimulated depolarization currents. By using K{sub 2}O rich KTaO{sub 3} targets and specific deposition conditions, KTaO{sub 3-{delta}} oxygen deficient thin films with a K/Ta = 1 ratio were obtained. Room temperature X-ray diffraction patterns show that KTaO{sub 3-{delta}} thin films are under a compressive strain of 2.3% relative to KTaO{sub 3} crystals. Leakage current results reveal the presence of a conductive mechanism, following the Poole-Frenkel formalism. Furthermore, dielectric, polarization, and depolarization current measurements yield the existence of a polarized state below T{sub pol} {approx} 367 Degree-Sign C. A Cole-Cole dipolar relaxation was also ascertained apparently due to oxygen vacancies induced dipoles. After thermal annealing the films in an oxygen atmosphere at a temperature above T{sub pol}, the aforementioned polarized state is suppressed, associated with a drastic oxygen vacancies reduction emerging from annealing process.
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science of University of Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)
  2. INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)
  3. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)
  4. Centro de Quimica, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal)
Publication Date:
OSTI Identifier:
22122842
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 3; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CRYSTALS; DEPOLARIZATION; DEPOSITION; DIELECTRIC MATERIALS; LEAKAGE CURRENT; MAGNETRONS; PERMITTIVITY; POLARIZATION; POTASSIUM COMPOUNDS; POTASSIUM OXIDES; RELAXATION; SILICON OXIDES; SUBSTRATES; TANTALATES; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; VACANCIES; X-RAY DIFFRACTION