Abstract: As a new type of nonvolatile memory, the resistive memristor has broad application prospects in information storage and neural computing based on its excellent resistive switching (RS) performance. At present, it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/off ratio of ferroelectric memristors. Herein, epitaxial Pb(Zr_0.40Ti_0.60)O₃ (PZT) thin films with low content Ca doping were deposited on the Nb:SrTiO₃ substrate to prepare PCZT/NSTO heterostructures and their RS behaviors were studied. The research findings show that compared with pure PZT film, the ferroelectric polarization of 1-mol%-Ca-doped PZT film is slightly improved, while the leakage current is increased by three orders of magnitude. Therefore, the RS on/off ratio reaches 2.5 × 10⁵, about three orders of magnitude higher than pure PZT films. The theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current mechanism. Our results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance, which provides a good reference for the development of high-performance ferroelectric memristor devices.

Key words: Ferroelectric memristor, Ca-doped PZT, Ferroelectric polarization, Oxygen vacancies, Resistive switching