Effects of Spent Coffee Grounds on Improvement of Resistive Switching Characteristics in Natural Rubber-Based Memory

The recent upsurge in environmental awareness provokes the widespread usage of green materials in sustainable electronic applications. Herein, the effects of spent coffee grounds (SCGs) on natural rubber (NR)-based resistive switching (RS) memory are systematically investigated. This study presents the fabrication of a metal-insulator-metal (MIM) structure using NR incorporated with SCGs (0 to 8 wt.%) as a memristive layer and sandwiched between electrodes. A significant improvement in the ON/OFF ratio from 10⁴ for pure NR to 10⁷, read memory window increased from 2.03 to 2.45 V with improved stability even after 130 cycles of switching is achieved with the optimal concentration of SCGs (6 wt.%). The improved performance after the incorporation of SCGs is attributed to the introduction of key chemical functional groups (C═O, C═C) in the memristive film. By varying the viscosity of NR, bending of test structure, and voltage sweep rate, the effects of trap density and location on the RS performance are established. The RS mechanisms in high and low resistance states are dominated by space-charge-limited conduction and Ohm's law, respectively. This research manifests the potential of SCGs in improving the RS performance of bioorganic-based memory devices.