A transparent and flexible organic bistable memory device using parylene with embedded gold nanoparticles

In this work, we demonstrate the fabrication of a transparent and flexible memory device in the simple structure of metal/dielectric/metal (MIM). Here, the MIM structure consists of gold electrode/200 nm Parylene-C/20 nm gold nanoparticles/100 nm Parylene-C/indium-tin-oxide (ITO) coated polyethylene terephthalate (PET). The use of parylene as the dielectric layer is important to ensure that there is no thermal stress induced on the flexible ITO/PET substrate compare to other reported works using various organic dielectrics that require high temperature curing. In addition, parylene deposition does not disturb the drop-casted gold nanoparticles. Hence, the use of parylene will be the right step forward in the fabrication of mechanically flexible and optically transparent devices. Current versus voltage (I–V) plot shows the presence of hysteresis suggesting the charge storage capability as a memory device. In the I–V plot, three distinct regions based on the slope have been identified and the transport mechanisms are discussed and explained. The fabricated device shows similar behavior as write-once-read-many memory device and can be programmed with either positive or negative bias voltage. However, the memory device shows unstable current state when being bent under different curvature diameters.