Leakage current mechanisms in lead-based thin-film ferroelectric capacitors

Current-voltage (Formula presented) behaviors of (Formula presented)-based capacitors with (Formula presented) electrodes were studied to investigate the dominant leakage mechanism. Epitaxial (Formula presented) capacitors were fabricated to simplify the analysis and eliminate any effects of granularity. The (Formula presented) characteristics were almost symmetric and temperature dependent with a positive temperature coefficient. The leakage current at low fields (<0.5 V or 10 kV/cm) shows Ohmic behavior with a slope of nearly 1 and is nonlinear at higher voltages and temperatures. Further analysis suggests that at higher fields and temperatures, bulk-limited field-enhanced thermal ionization of trapped carriers (i.e., Poole-Frenkel emission) is the controlling mechanism. The activation energies calculated for the films are in the range 0.5–0.6 eV. These energies are compatible with (Formula presented) ion acting as the Poole-Frenkel centers. © 1999 The American Physical Society.