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

Abstract

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 × 104 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 103 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.

Resistive Switching of the Tetraindolyl Derivative in Ultrathin Films: A Potential Candidate for Nonvolatile Memory Applications

“…For practical and commercial applications, a lower switching voltage is advantageous. 42 Various switching parameters as extracted from I−V curves showing bipolar switching for both of the above devices along with some other similar reports of switching using organic molecules are listed in Table 1. The ON/OFF current ratio is an important criterion for switching devices in the case of memory applications.…”

“…41 In these bipolar switching devices, the SET (transition from HRS to LRS) operation represents a "writing" operation for memory applications. 23,42 The ON state (LRS) can be retained in the device even after the removal of bias, and the device subsequently returned to its OFF state (HRS) (erasing process) under the opposite bias. 23,42 To determine the directional dependence on the observed switching, we have also studied the I−V characteristics by reversing the initial sweep direction.…”

“…23,42 The ON state (LRS) can be retained in the device even after the removal of bias, and the device subsequently returned to its OFF state (HRS) (erasing process) under the opposite bias. 23,42 To determine the directional dependence on the observed switching, we have also studied the I−V characteristics by reversing the initial sweep direction. Here, initial scanning was applied from −V max to +V max .…”

“…However, in higher-voltage regions it follows quadratic behavior. 42,46 Such charge transport behavior can be explained in terms of electron-injected trap-controlled space−charge limited conduction (SCLC) theory. 46,49 At low voltage, the linear behavior follows Ohm's law due to a thermally generated free electron within the film.…”

Redox‐Active Vanadium‐Based Polyoxometalate as an Active Element in Resistive Switching Based Nonvolatile Molecular Memory

“…If HRS to LRS (device OFF → device ON, known as SET process) and LRS to HRS (device ON → device OFF, known as RESET process) switching are obtained in single polarity of bias voltage, the switching is called “unipolar”; [ 19 ] whereas, if they occur at opposite bias polarities it is called “bipolar”. [ 20 ] NVM based on such resistive switching (RS) event has been so far reported for variety of materials, such as inorganic perovskites, [ 21 ] organic–inorganic hybrid polymer, [ 22 ] protein, [ 23 ] glucose, [ 20 ] graphene oxide, [ 24 ] silicon dioxide, [ 25 ] organic compounds, [ 26,27 ] Mott insulators, [ 28 ] ferroelectrics, [ 29 ] metal sulfide, [ 30 ] 2D materials such as hexagonal boron nitride [ 31 ] and transition metal dichalcogenides, [ 32 ] binary transition metal oxides, [ 15,33,34 ] and other chalcogenide materials. [ 35 ]…”