Dual harmonic Kelvin probe force microscopy for surface potential measurements of ferroelectrics

Applications of Ferroelectrics held jointly with 2012 European Conference on the Applications of Polar Dielectrics and 2012 International Symp Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials (ISAF/ECAPD/PFM), 2012 Intl. Symp., 9th-13th of July 2012 University of Aveiro Aveiro, PortugalIn this work, we implemented dual harmonic Kelvin probe force microscopy (DH-KPFM) for surface potential mapping of ferroelectric thin films, namely bismuth ferrite (BFO) and strontium barium niobate (SBN). We applied DH and conventional KPFM to charge-patterned BFO and found agreement between recorded relative surface potential values between domains, demonstrating that DH-KPFM can be used for quantitative mapping of relative surface potentials. We used piezoresponse force microscopy (PFM) to determine whether polarization switching had occurred. From the PFM data, we found that BFO was poled successfully, and that the measured surface potential was consistent with the sign of the bound polarization charge. For SBN, a thin surface layer was evident in the topography after the application of DC bias, suggesting an electrochemical reaction had taken place between the tip and the sample. We used DH-KPFM to simultaneously map the surface potential and changes in the dielectric properties resulting from this surface layer. The results presented herein demonstrate that DH-KPFM can be used for electric characterization of voltagesensitive materials, and we anticipate that DH-KFPM will become a useful tool for non-intrusive electrical characterization of materials.Science Foundation IrelandOther funderUCD Research and Science Foundation Ireland (10/RFP/MTR2855 and 07/IN1/B931). Australian Research Council (DP1092717 and DP110100262) Alexander von Humboldt Foundationkpw22/10/1