Statistical Analysis of Uniform Switching Characteristics of TaO-Based Memristors by Embedding In-Situ Grown 2D-MoS Buffer Layers.

A memristor based on emerging resistive random-access memory (RRAM) is a promising candidate for use as a next-generation neuromorphic computing device which overcomes the von Neumann bottleneck. Meanwhile, due to their unique properties, including atomically thin layers and surface smoothness, two-dimensional (2D) materials are being widely studied for implementation in the development of new information-processing electronic devices. However, inherent drawbacks concerning operational uniformities, such as device-to-device variability, device yield, and reliability, are huge challenges in the realization of concrete memristor hardware devices. In this study, we fabricated TaO-based memristor devices, where a 2D-MoS buffer layer was directly inserted between the TaO switching layer and the Ag metal electrode to improve uniform switching characteristics in terms of switching voltage, the distribution of resistance states, endurance, and retention. A 2D-MoS layered buffer film with a 5 nm thickness was directly grown on the TaO switching layer by the atomic-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) method, which is highly uniform and provided a superior yield of 2D-MoS film. It was observed that the switching operation was dramatically stabilized via the introduction of the 2D-MoS buffer layer compared to a pristine device without the buffer layer. It was assumed that the difference in mobility and reduction rates between TaO and MoS caused the narrow localization of ion migration, inducing the formation of more stable conduction filament. In addition, an excellent yield of 98% was confirmed while showing cell-to-cell operation uniformity, and the extrinsic and intrinsic variabilities in operating the device were highly uniform. Thus, the introduction of a MoS buffer layer could improve highly reliable memristor device switching operation.