Abstract
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.
Highlights
In the past few decades, information processing technology regarding mobile edge devices has been developed in accordance with to the rapid population of the Big Data and Internet of Things (IoT) era, whereby the amount of data has improved explosively [1]
Various types of non-volatile memory devices have been proposed for use in neuromorphic core hardware, such as resistive random-access memory [5,6,7] phase-change RAM [8,9] spin-transfer torque magnetoresistive RAM (STT-MRAM) [10,11], and conventional flash memory [12], respectively
To measure the electrical properties, the bottom electrode (BE) was grounded and external voltage was applied to the top electrode (TE)
Summary
In the past few decades, information processing technology regarding mobile edge devices has been developed in accordance with to the rapid population of the Big Data and Internet of Things (IoT) era, whereby the amount of data has improved explosively [1]. Conventional von Neumann architecture has a physically separated structure of memory and computing data; with with frequent data transfer process, the transfer bottleneck of delay with increasing power consumption dramatically increases. RRAM devices are promising candidates for use in overcoming structural problems of von Neumann computing, because with these devices, computing and storage functions can be performed in the same circuit, enabling processing-in-memory (PIM) computing [13,14,15,16,17]. Among various 2D materials, molybdenum disulfide (MoS2 ) has a low power consumption, band gap tunability, high effective mobility, and rapid switching speed, which show that MoS2 is a promising candidate for use in vertical or lateral electrical devices such as field-effect transistors (FETs), non-volatile memory devices, junction diodes, and flexible optical sensors [23,24,25]. The exceptional device yield was achieved in 98% of 100 device cells
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