Publication Type:Journal Article
Source:Nano Letters, Volume 13, Number 4, p.1410-1415 (2013)
Keywords:Aberration-corrected scanning transmission electron microscopies, Article, beryllium, beryllium oxide, chemistry, Crystal defects, Device optimization, Dislocations (crystals), Domain walls, Edge dislocations, electricity, Electromechanical coupling, electron, Electronic, Ferric Compounds, ferric ion, ferric oxide, Ferroelectric field effect transistors, Ferroelectric thin films, ferroelectricity, Field effect transistors, Finite size effect, Lattice structures, microscopy, nanomaterial, Nanostructures, particle size, Phase-field simulation, Piezoelectric couplings, Piezoelectric tensor, piezoelectricity, Polarization, Scanning Transmission, scanning transmission electron microscopy, semiconductor, transistors, transmission electron microscopy
The performance of ferroelectric devices, for example, the ferroelectric field effect transistor, is reduced by the presence of crystal defects such as edge dislocations. For example, it is well-known that edge dislocations play a crucial role in the formation of ferroelectric dead-layers at interfaces and hence finite size effects in ferroelectric thin films. The detailed lattice structure including the relevant electromechanical coupling mechanisms in close vicinity of the edge dislocations is, however, not well-understood, which hampers device optimization. Here, we investigate edge dislocations in ferroelectric BiFeO3 by means of spherical aberration-corrected scanning transmission electron microscopy, a dedicated model-based structure analysis, and phase field simulations. Unit-cell-wise resolved strain and polarization profiles around edge dislocation reveal a wealth of material states including polymorph nanodomains and multiple domain walls characteristically pinned to the dislocation. We locally determine the piezoelectric tensor and identify piezoelectric coupling as the driving force for the observed phenomena, explaining, for example, the orientation of the domain wall with respect to the edge dislocation. Furthermore, an atomic model for the dislocation core is derived. © 2013 American Chemical Society.
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