Resolving the discrepancy between coercive voltages extracted from C-V and P-V measurements in a ferroelectric capacitor

Abstract

In this work, we study hafnium zirconate (HZO) based ferroelectric (FE) capacitors (FeCAP) intended for random access memory and compute-in-memory (CiM) applications. We show that there exists a discrepancy between the coercive voltages (V-C) extracted from a small-signal capacitance-voltage (C-V) measurement ({V-C}(CV)) and dynamic polarization-voltage (P-V) measurement ({V-C}(PV)): |{V-C}(CV)| < |{V-C}(PV)|. Utilizing the Nucleation Limited Switching (NLS) framework, we attribute the origin of this discrepancy to the difference in voltage-time dynamics experienced by the FE during the C-V and P-V measurements, resulting in a higher switching probability at the same applied voltage for a longer time during the C-V measurement: |{V-C}(CV)| < |{V-C}(PV)|. Therefore, experimentally obtained V-C values do not solely reflect an intrinsic material property of the FE as they depend on the voltage-time dynamics of the measurement.