Improvement of non-volatile resistive memory behaviour in post-annealed rGO-SnS2 embedded PMMA polymer nanocomposites film

Abstract

Two-dimensional (2D) materials used to form nanohybrids have emerged as promising components for controlling carrier confinement and transportation in resistive memory devices. To investigate the memristive properties in a metal–insulator–metal (MIM) configuration, nanohybrid of reduced graphene oxide-tin disulfide (rGO-SnS₂) was synthesized and incorporated with poly (methyl methacrylate) (PMMA) matrix to prepare the polymer nanocomposites (PNCs). The crystallinity and uniformity of the spin-coated PNCs film over the ITO substrate are enhanced through annealing at 200 °C for 4 h in order to improve the resistive switching properties in memory devices. Furthermore, the optical, structural, and morphological characteristics of the films are done using various spectroscopic and microscopic techniques, namely, UV–Visible DRS, Raman, X-ray diffraction (XRD), Atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) is performed to ensure the stability and structural integrity of the material. XRD analysis shows the drastic reduction in the peak intensity of the film annealed at 250 °C suggesting the deterioration of the film’s crystallinity. In contrast, the film annealed at 200 °C shows better crystallinity than the as-deposited film resulting in enhanced memory behaviour. The post-annealed thin film (200 °C)-based devices exhibit write-once-read-many (WORM) memory characteristics with lower switching voltage (< 2 V) and enhanced switching ratio (\(\frac{{I}_{ON}}{ {I}_{OFF}}\)) ~ 10⁴. For resistive switching technology, rGO-SnS₂ delivers beneficial outcomes like improved trapping mechanisms and enhanced charge transport channels. The interface at the rGO and SnS₂ in the nanohybrid plays a pivotal role in the separation of charge carriers and charge conduction process in the device. A theoretical concept is elucidated to clarify the charge transport mechanism through the devices that follows space charge limited current (SCLC) conduction and Ohm’s law in the high resistance state (HRS) and low resistance state (LRS), respectively. Moreover, the charge transport phenomenon in the device is explained using a plausible energy band diagram.