Functionality of ferroelectric materials is defined by the number of physical and chemical phenomena on the nanoscale, which requires using of nanoscale investigative techniques. Atomic Force Microscopy (AFM) is one of such techniques, which is widely used for characterization of the ferroelectric physical properties. But at the same time, chemical contribution in the ferroelectric phenomena in the most cases are ignored. However, these studies can be carried out by combination of AFM with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), allowing nanoscale local investigations of the chemical properties. Here, we utilize combine AFM/ToF-SIMS approach for correlated investigations of the functional and chemical phenomena in PbZr0.2Ti0.8O3 thin film. In the studies, we used AFM to induce local ferroelectric switching by the electric field of the biased tip and study associated local changes in the chemistry of the film by ToF-SIMS. Investigations showed 3 - 5% change in the spatial concentrations of the base chemical elements close to the sample surface. Those changes were localized within 3.5 nm surface layer are caused by the screening process minimizing depolarization electric fields produced by the boundary charges. Observed phenomenon was also found to be reversible by application of the electric field of opposite polarity, which confirms its ferroelectric origin. Results of the study shed light on the chemical phenomena associated with ferroelectric properties and are important for their fundamentals investigations and practical applications.
This work was conducted at the Center for Nanophase Materials Sciences, which is a Department of Energy (DOE) Office of Science User Facility.