Highly Controllable Multilevel Performance in WS2 Quantum Dots-Based Memristor

Multilevel resistive random access memory (RRAM) yields an effective pathway for improving the storage density in the era of big data. However, emerging applications requiring highly controllable and reliable multilevel RRAMs remain an unsolved challenge. Herein, a highly controllable multilevel Al/polymethyl methacrylate/WS2-quantum dots (QDs)/polymethyl methacrylate/fluorine-doped tin oxide-structured (WS2 QDs-based device) RRAM is proposed, synthesized via a facile spin-coating process. The proposed device exhibits bipolar resistive switching behavior with an ON/OFF ratio of $10^{{3}}$ , stable endurance and retention, and its resistive switching properties are highly dependent on the WS2 QDs concentration. According to the results of Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (C-AFM), the resistive switching mechanism is attributed to the formation/rupture of conductive filaments caused by carrier trapping and de-trapping. Moreover, by varying the top electrode areas, the resistive switching behaviors and the resistance states of the device are effectively regulated. The multilevel performance is scrutinized systematically by tuning the compliance currents and stop voltage to the device. Under different compliance currents, there are three low resistance states (LRSs) and one high resistance state (HRS), and three HRSs and one LRS under different stop voltages. Notably, this study proposes a strategy for fabricating a highly controllable multilevel RRAM, facilitating the development of high-density polymer-based storage media.