Reproducibility and ferroelectric fatigue of lead zirconate titanate thin films deposited directly on copper via a composite gel architecture

Integrating ferroelectric lead zirconate titanate (PZT) thin films directly on copper metal foils has high commercialization potential. PZT films on copper foils eliminate costly noble metal or conductive oxide electrodes and make available a flexible substrate technology that can be readily laminated into printed wiring boards. Unlike noble metals, copper substrates are potentially reactive, and therefore susceptible to processing fluctuations that offer negligible consequences to noble metal-based systems. Herein, the reliability of the composite gel architecture route for synthesizing PZT thin films directly on copper foils is explored. Reproducibility in film properties and avoidance of solution aging effects are demonstrated. Fatigue cycling is used to evaluate electrical durability. Ferroelectric switching with polarization saturation is demonstrated after 1 billion cycles. Loss in spontaneous polarization is recovered with postfatigue annealing demonstrating the high material integrity necessary for commercial device performance, and distinct similarity to the behavior over time with noble metal electrode capacitors.