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Title: Direct observation of oxygen-vacancy-enhanced polarization in a SrTiO{sub 3}-buffered ferroelectric BaTiO{sub 3} film on GaAs

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 microscopy 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.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ; ;  [4] ;  [3] ;  [2] ;  [2] ;  [5] ; ;  [1]
  1. Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607 (United States)
  2. (United States)
  3. Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240 (United States)
  4. Ingram School of Engineering, Texas State University, San Marcos, Texas 78666 (United States)
  5. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575 (Singapore)
Publication Date:
OSTI Identifier:
22486083
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 20; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DENSITY FUNCTIONAL METHOD; FERROELECTRIC MATERIALS; GALLIUM ARSENIDES; OPTOELECTRONIC DEVICES; OXIDES; OXYGEN; POLARIZATION; SEMICONDUCTOR MATERIALS; STRONTIUM TITANATES; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES