Controllable Electrical Properties of ZrO₂/BiFeO₃ Bilayer Memristor from Synaptic Mimic to TRNG Circuit Application by Modulating Compliance Currents

Abstract

Apart from simulating biological synapses, memristors can also be used in the secure encryption by exploiting their inherent random resistive switching (RS) properties. In this work, nonvolatile Ta/BiFeO3/ZrO2/Pt memristor is fabricated with 2 nm inserting BiFeO3 layer. At a high compliance current of 10 mA, it presents gradual RS characteristics during the set process, which resulting in 30 conductance states. Synaptic behavior can be successfully mimicked by precise conductance modulating under pulse electrical stimulation. Whereas under a low compliance current of 500 µA, it exhibits abrupt RS behavior, and the set voltage ranged from 0.3–0.8 V, which can be effectively as an entropy source for true random number generator (TRNG). Due to its Shannon entropy of 300 bits is 0.99987, Hamming weights and intra‐Hamming distances tend to be 50%. Furthermore, the software simulation of encryption and decryption of cat image is achieved by combining the key generated by TRNG. The controllable electrical properties of the Ta/BiFeO3/ZrO2/Pt device can be modulated by the compliance current, thus meeting the computing or safety requirements, which provides a solid foundation for the development of integrating computation and security at the hardware level.