Low power Resistive Switching behavior of Cobalt/Iron Oxide Nanoparticle assembly with Symmetric Negative Differential Resistance

A resistive switching (RS) phenomena in very low power of order 1 nW is observed in an assembly of Iron Oxide nanoparticles. The samples are prepared on glass substrate using spin coating of a solution of 70.7 mM Fe(III) acetylacetonate in acetone followed by annealing at 550°C for 75 minutes in air. When Current-Voltage (I-V) characteristics is taken by sweeping the voltage in a triangular waveform of amplitude 10 V at the rate of 0.1 V/s, the device takes the low resistive state (LRS) initially going from 0 V to 10 V and at some voltage the current starts to drop sharply showing negative differential resistance (NDR) and takes high resistive state (HRS) when returning from 10 V to 0 V. The I-V curves are symmetric and highly reproducible and shows RS and NDR phenomena in the negative bias as well. The RS and symmetric NDR behavior of the device is attributed to the trapping and de-trapping of the carriers at the interface layer formed due to the interaction of oxygen vacancies and the moisture in the humid air. A solution of 70.1 mM of Co(III) acetylacetonate in acetone is mixed into the previous solution, where the inclusion of Co increases the ratio of HRS/LRS to ~150%. The improvement in the HRS/LRS may be due to the higher reactivity of Cobalt, which, in turn, increases the density of oxygen vacancies in Iron oxide. For all samples, a ratio of HRS/LRS >7 was achieved in both positive and negative bias regions.