Publication Type:Journal Article
Source:ACS Applied Materials and Interfaces, American Chemical Society, Volume 8, Number 43, p.29588-29593 (2016)
Keywords:atomic force microscopy, Chemical phenomenas, Chlorine, Crystallography, Electrochemical phenomena, Electrochemistry, Ferroelectric films, Ferroelectric switching, Ferroelectric thin films, ferroelectricity, ions, Long range interactions, mass spectrometry, Optical switches, Polarization, polarization switching, Secondary emission, Secondary ion mass spectrometry, Significant surfaces, spectrometry, surface chemistry, Surface electrochemistry, Switching, Time of flight secondary ion mass spectrometry
Domain formation and ferroelectric switching is fundamentally inseparable from polarization screening, which on free surfaces can be realized via band bending and ionic adsorption. In the latter case, polarization switching is intrinsically coupled to the surface electrochemical phenomena, and the electrochemical stage can control kinetics and induce long-range interactions. However, despite extensive evidence toward the critical role of surface electrochemistry, little is known about the nature of the associated processes. Here we combine SPM tip induce polarization switching and secondary ion mass spectrometry to explore the evolution of chemical state of ferroelectric during switching. Surprisingly, we find that even pristine surfaces contain ions (e.g., Cl-) that are not anticipated based on chemistry of the system and processing. In the ferroelectric switching regime, we find surprising changes in surface chemistry, including redistribution of base cations. At higher voltages in the electroforming regime significant surface deformation was observed and associated with a strong ion intermixing. © 2016 American Chemical Society.
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