Tuning of bipolar resistive switching and memory characteristics of cadmium sulphide nanorods embedded in PMMA matrix

Abstract

Resistive switching of polymer films embedded with 1D inorganic nanofillers have emerged as a high performance candidate for their promising applications in next-generation organic switching and memory devices. Herein, we report organic switching devices (OSDs) with cadmium sulphide (CdS) nanorods (NRs) encapsulated within a polymer layer, sandwiched between aluminum (Al) and indium tin oxide (ITO) electrodes. CdS-NRs were synthesized by following a simple and low cost technique and dispersed with different wt% in poly methyl-methacrylate (PMMA) to prepare the nanocomposites and spin-casted on the ITO substrates to fabricate the devices (ITO/PMMA-CdSNRs/Al). The morphology, crystal phase, and structural properties of the CdS NRs were carefully investigated with the help of various characterization techniques such as UV-visible absorption, photoluminescence (PL), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The current density versus voltage (J-V) characteristics of the fabricated devices were noted and switching performances were studied by varying the weight percent (wt %) of the nanofillers. All the devices exhibited bipolar resistive switching characteristics at lower switching voltage ( < 2 V). With increasing the wt% of CdS NRs, the shifted towards the lower voltage region, whereas current density ON/OFF (JON/JOFF) ratio decreased. Retention (104 s) and endurance test (1000 cycles) were performed for all the devices which indicates that the fabricated devices were highly stable under repeated sweep showing excellent memory characteristics. Also, the J-V characteristics of the fabricated devices were fitted to discuss the conduction mechanism. Schematic band diagram is proposed to explain bi-stable behavior of the fabricated devices.