Direct observation of oxygen-vacancy-enhanced polarization in a SrTiO3-buffered ferroelectric BaTiO3 film on GaAs
Abstract
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 SrTiO3 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 BaTiO3 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 BaTiO3 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 BaTiO3), and propose that the presence of surface charge screening allows the formation of switchable domains.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 16, 2015
- Source ID
- 10.1063/1.4936159
Entities
People
- Qiao Qiao
- Ravi Droopad
- Robert F Klie
- Rocio Contreras-guerrero
- Serdar Ogut
- Sokrates T. Pantelides
- Stephen J. Pennycook
- Yuyang Zhang
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- National University of Singapore
- Oak Ridge National Laboratory
- Texas State University
- United States Department of Energy
- University of Illinois at Chicago
- Vanderbilt University