An Organic Bipolar Resistive Switching Memory Device Based on Natural Melanin Synthesized From Aeromonas sp. SNS

A Ag/melanin/SS memristive device with remarkably good endurance and retention properties is demonstrated using natural melanin isolated from bacterium Aeromonas sp. SNS. Purified and characterized melanin is used for the development of a non-volatile memory device. The device is operated under electroforming-free mode and requires only +/- 0.6 V resistive switching voltage. 2 x 10(4) switching cycles endurance is achieved with an approximately 10X memory window at 0.2 V read voltage. In addition to this, the low resistance state (LRS) and high resistance state (HRS) are stable over 10(3) s without any observable degradation in the resistance states. Standard deviation and coefficient of variation of LRS and HRS are very small compared to other memory devices reported in the literature. Furthermore, the Ag/melanin/SS memristive device shows rich nonlinear behavior and possesses negative differential resistance effect during positive bias. Charge transportation in the device is due to the ohmic and space charge limited current. The formation and breaking of the conductive filament are responsible for the bipolar resistive switching effect due to hybrid electronic-ionic charge transportation. Rich I-V characteristics, very low switching voltage, and remarkable nonvolatile memory performance make melanin a strong candidate for next generation organic non-volatile memory devices.