POLARIZATION VARIATIONS DUE TO DISLOCATION CONFIGURATIONS IN HETEROEPITAXIAL FERROELECTRIC LAYERS

ABSTRACT

Dislocation networks in epitaxial ferroelectric thin films consist of misfit and threading dislocations. They usually form at high temperatures during film growth when the film is paraelectric. Once the film becomes ferroelectric upon cooling, they induce spatial polarization gradients which are detrimental to the desired properties. This study analyzes the ways in which they affect the ferroelectric properties. A qualitative comparison is made using thermodynamic and electrostatic analysis concluding that the misfit segments of dislocations are more detrimental than the threading segments.

Keywords:

• Ferroelectric thin films
• dislocations
• thickness effects
• thermodynamics
• electrostatics

ACKNOWLEDGMENTS

The work at UConn was supported by the National Science Foundation (NSF) under Grant DMR-0132918 and by the American Chemical Society, The Petroleum Research Fund. The authors thank V. Nagarajan for many useful discussions.