Published online by Cambridge University Press: 01 February 2011
Electrical bistability is reported in metal-organic-metal diodes. The device consists of two Al electrodes separated by an organic layer that contains embedded Au nanoparticles (NPs) supported by parylene nanopillars. This paper presents results with two different organic materials: 2-amino-4, 5-imidazoledicarbonitrile (AIDCN) and aluminum tris(8-hydroxyquinoline) (Alq3). Electrical characterization of the diodes shows bistability with two well-defined states with high (OFF) and low (ON) resistances. The ON/OFF ratio is 104 and current-voltage (I-V) curves show a negative differential resistance (NDR). The diodes can be programmed in either the ON or the OFF state and maintained it for at least 8 months in air without any evidence of degradation. This conspicuous memory effect is rationalized in terms of charge storage mediated by the oxidation/reduction of the NPs. The fabrication method is general and provides a good control on both the size-uniformity and the position of the Au NPs embedded in the organic materials. The diode characteristics with different NP density are also addressed.