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 snap-forward effects in the switching dynamics. The I-V characteristics 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.