IMF2017

The investigation of displacement currents arising from polarization switching is a commonly employed method used to explore ferroelectric hysteresis. However, in the nanoscale measurement using an atomic force microscope (AFM) tip, traditional current-voltage (I-V) curve acquisition is generally too slow to measure this transient current, and thus nanoscale studies have focused on the use of complementary techniques such as piezoresponse force microscopy (PFM). Here we present a method to simultaneously increase the rate of acquisition of I-V curves by a factor of ~200x, through use of AC excitation to the tip, full information acquisition, and Bayesian inference. We successfully observe switching current in ferroelectric Pb(Zr_0.2Ti_0.8)O₃ thin-film nanocapacitors, with results indicating contamination towards the center of nanocapacitors, varying leakage levels, and also allow determination of the dielectric constant of the individual nanocapacitor structures. Analysis of the switching current profiles enables determination of degree of disorder, which can be spatially mapped and provides a complementary channel to supplement PFM. This study shows the utility of the full information acquisition and Bayesian inference approach, and can be extended to scanning tunneling microscopy for rapid electronic characterization. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE (RKV, SVK, PM,SS). This research was conducted and partially supported (SJ) at the Center for Nanophase Materials Sciences, which is a US DOE Office of Science User Facility. The Bayesian inference was sponsored by the Applied Mathematics Division of ASCR, DOE; in particular under the ACUMEN project (KJHL, RA).