• Vilkman, Marja
• Sandberg, Henrik G. O.
• Solehmainen, Kimmo
• Hassinen, Tomi

Abstract

A flexible organic memory unit will be a key element whenmanufacturing future RFID circuits on flexiblesubstrates. Although the research of memory devices usingorganic materials dates back almost 40 years, theperformance of these devices has remained low whencompared to their inorganic counterparts. The mainproblem limiting the application of these devices is thattheir operation tends to degrade in air and under stressof successive read-write cycles. Furthermore, thephysical phenomena affecting their stability are manytimes unclear. In this study many different aspectsrelated to the sample preparation were studied in orderto identify which of them had an influence on theperformance and stability of the devices. The test devicestructure consisted of two metal electrodes and anorganic layer between them. As the organic film differentpolymer materials including block polymers, poly(3-hexylthiophene) (P3HT), and polystyrenes were tested invarious compositions. The film thickness varied from afew tens of nanometres to ~200 nm. During the work,different electrode materials, interface effects, filmthickness, device area, substrate materials, impurityeffects, and curing parameters etc. were studied.Results from the electrical characterisation showed thatelectrical switching took place in all of the testedmaterials but not in all fabrication parametercombinations. One of the most important aspects in thesample preparation affecting the device performance wasthe purity of processing environment. The importance ofthe dust particles in constituting conducting paths tocharge carriers and thereby enabling electricalconductivity was identified. In addition to the purity ofthe processing environment the interface effects played amajor role in the operation of the devices.

Topics

• impedance spectroscopy
• polymer
• thin film
• electrical conductivity
• curing