Low Energy and Analog Memristor Enabled by Regulation of Ru ion Motion for High Precision Neuromorphic Computing

Mobile species and matrix materials in ion motion‐mediated memristors predominantly determine the switching characteristics and device performance. As a result of exploring a new type of mobile species, a Ru ion‐mediated electrochemical metallization‐like memristor with an amorphous oxide matrix is recently suggested to achieve a low switching current, voltage, and good retention simultaneously. Although the ion migration of Ru in the oxide matrix is previously confirmed, no in‐depth study on how the crystallinity of the oxide matrix influences the Ru ion motion and switching characteristics has not been reported. Therefore, in this study, the crystallinity‐dependent resistive switching behavior of the Pt/HfO2/Ru structure device is investigated. With the crystallized HfO2 layer, the preferred Ru ion migration through the grain boundaries occurs owing to the enhanced ion mobility, resulting in a high switching current (≈100 µA) with continuous metallic Ru conducting filaments. The discontinuous conducting filaments with amorphous HfO2 exhibit a low switching current. In addition, highly linear and symmetric conductance modulation properties are achieved, and over 91.5% accuracy in the Mixed National Institute of Standards and Technology (MNIST) pattern recognition test is demonstrated. The crystallinity‐dependent resistive switching behavior of the Pt/HfO2/Ru device is investigated. With the amorphous HfO2 layer, Ru ion motion is restricted due to the high activation energy for ion diffusion, resulting in the formation of discontinuous conducting filaments, which induces a low switching current. This device shows highly linear and symmetric conductance modulation properties, achieving over 91.5% pattern recognition accuracy.