Tunability Properties and Compact Modeling of HfO₂-Based Complementary Resistive Switches Using a Three-Terminal Subcircuit

Complementary resistive switching (CRS) arises when two bipolar-mode memristive devices are antiserially connected, forming a single functional structure. The combined effect of both memristors leads to the appearance of high (HRS) and low (LRS) resistance windows in the current-voltage (I-V) characteristic that finds application in fields such as neuromorphic computing and logic circuits. In this work, the electric behavior of HfO2-based CRS devices intentionally fabricated with a common central electrode is investigated both from experimental and modeling viewpoints. Experiments reveal that the maximum voltage applied to the structure allows tuning the amplitude of the resistance window following a self-balance dynamics. The origin of the abrupt (digital) and gradual (analog) transitions between the HRS and LRS states is elucidated through the inclusion of the snapback and snapforward effects in the switching dynamics. TheI-Vcharacteristics of the CRS devices are compact modeled with two opposite-biased memdiodes and simulated in LTSpice using an equivalent three-terminal subcircuit. It is shown that the proposed model is able to reproduce with a high degree of accuracy not only the observed CRS behavior for HfO2 but also the main features exhibited by devices with a wide variety of oxide/electrode materials.