Statistical Analysis of Uniform Switching Characteristics of Ta2O5-Based Memristors by Embedding In-Situ Grown 2D-MoS2 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 Ta2O5-based memristor devices, where a 2D-MoS2 buffer layer was directly inserted between the Ta2O5 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-MoS2 layered buffer film with a 5 nm thickness was directly grown on the Ta2O5 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-MoS2 film. It was observed that the switching operation was dramatically stabilized via the introduction of the 2D-MoS2 buffer layer compared to a pristine device without the buffer layer. It was assumed that the difference in mobility and reduction rates between Ta2O5 and MoS2 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 MoS2 buffer layer could improve highly reliable memristor device switching operation.

Research on Improving the Working Current of NbOx-Based Selector by Inserting a Ti Layer

To achieve the highest possible integration storage density in the V-point structure, the working current of the selector in the one-selection one-resistance (1S1R) structure should match with the resistance random access memory (RRAM). In this study, a selector device is designed with a Ti/NbOx/Ti/Pt structure through the magnetron sputtering method and achieves excellent performance of threshold switching under ultra-large compliance current (CC) up to 100 mA. Furthermore, both the switching voltages and the OFF-state resistance of the device demonstrate excellent stability even when CC is increased to a milliampere level, attributed from the existence of metallic NbO in the switching layer. This study provides evidence that a Ti/NbOx/Ti/Pt device has a great potential to drive RRAM in the V-point structure.

Selection of Switching Layer Materials for Memristive Devices: from Traditional Oxide to 2D Materials

Redox-based resistive switching devices (ReRAM) provide new hardware concepts which make it possible to break the von Neumann bottleneck and build a new computing system in the information. However, the materials for switching layers are various and mechanisms are quite different, these will block the further exploration for practical applications. This review tends to demonstrate different kinds of memristors fabricated with various materials, such as oxide, nitride and 2D materials. The electrical properties of those based on different materials are compared and the advantages of each are listed. It would give a guidance to the selection of materials of memristors.

MEMRISTOR STRUCTURES BASED ON THIN SI3N4 LAYERS AND CHARGE TRANSPORT MECHANISM RESEARCH

The article describes promising directions of development of non-volatile resistive memory ReRAM. Silicon nitride is a promising resistive switching layer for memristors. In this work we conducted an experimental researches of the switching effect and charge transport in memristores based on silicon nitride.