AgBiS2 quantum dot based multilevel resistive switching for low power electronics

Abstract

In the ever-expanding digital landscape, efficient solutions are needed that offer mass-producible, high-density, and low-power data storage capabilities to fulfill the growing demand for data storage. Memristive devices incorporating solution-processable metal chalcogenide quantum dots (QDs) have emerged as a viable solution within this framework. In this study, solution-processed ternary metal chalcogenide AgBiS₂ QDs are used as a functional layer via spin-coating method in a memristive device featuring an Al/AgBiS₂/ITO configuration. AgBiS₂ QDs of ∼6 nm size are synthesized using a hot injection method. The cubic structure of AgBiS₂ has been confirmed by X-ray diffraction (XRD). The Al/AgBiS₂/ITO device exhibits an electroforming free bipolar resistive switching (RS) behavior at low switching voltages of +0.3 V/−0.25 V. The endurance of the device has also been demonstrated for up to 500 cycles for +0.7 V/−0.7 V (set/reset) of 100 ms pulse signals. During the set process, a remarkably low power consumption of ∼0.065 mW was observed. The formation of a conductive filament (CF) was proposed as the working mechanism of the device. The migration of electrochemically active Ag metal ions and the sulfur vacancies has been associated with the formation of a CF. The contribution of sulfur vacancies to the filament formation is substantiated by the temperature-dependent resistance of the low resistance state (LRS). The mechanism has also been explained via an energy band diagram. Furthermore, multiple quantum conductance (QC) levels of 1G₀, 1.5G₀, 3G₀, 4G₀, and 5G₀ have been established by controlling the compliance current (CC) during the set process. The appearance of multiple QC-levels has been ascribed to the ballistic electron transport occurring within an atomic-size filament, wherein the lateral size of the filament increases in response to higher CC. These characteristics make the device suitable for ultra-high dense multi-level memory applications with low power consumption.