Internal Harmonic Displacement Field: A Model Dynamic for Hole-Electron Coupled Hysteresis Switching in Hf0.5Zr0.5O2

Abstract Polarization switching in ferroelectrics is an ideal platform to exploit dipoles performing holes- and electrons-coupled transport in an oscillating electric field. We propose an internal harmonic displacement field (IHDF) to fulfill such dynamics in the Hf2+(Zr2+)–O2− dipoles. The IHDF model is derived from Landau–Ginzburg mean-field theory, then incorporating the classical dipole resonance (DR) model and the kinetics model of Kolmogorov, Avrami, and Ishibashi (KAI) to become a contemporary DR-KAI-IHDF model. Conceptually, the dipoles can be classified into two subgroups. One is resistively-to-capacitively coupled interaction, inherent to the heavier Hf2+(Zr2+) ions. The other is resistively-to-inductively coupled interaction, belonging to the lighter O2− ions. Hole and electron differentiated mobility in the two ions is demonstrated to generate a short-range interaction correlated space charge symmetry breaking within the conservation of long-range rotation symmetry. Hallmark features of power switch in current, various loops in polarization, and two-butterfly hysteresis in capacitance are explored. The results are obtained via low-frequency ∼1 Hz current-voltage (I-V) and finite-frequency ∼100 Hz polarization-voltage (P-V) measurements performed on 5-nm-thick film Hf0.5Zr0.5O2 capacitors.