Large-area molecular junctions

Although still a relatively new field, molecular electronics can be regarded as the next evolutionary stage for plastic electronics. Molecular electronics holds the potential to fabricate elements for electronics circuits with a functionality that is embedded in just a single layer of molecules. Instead of using photolithography or printing techniques to etch or print nano-scale circuit features, molecular electronics can be engineered to use organic molecules that spontaneously form the correct structures via self-organization. Especially the theoretical prediction of unipolar rectifiers(1) has led to a worldwide effort on the experimental verification. Transport through single molecules has been investigated by scanning probes, break-junctions and metallic cross bar devices. Molecular devices have been reported showing intriguing phenomena as rectification, negative differential resistances, stochastic switching, the Kondo-effect and conductance switching. The reproducibility however, is doubtful. Rectification is due to contacts and not related to the functionality of the molecule; negative differential resistances appear to be due to irreversible electrochemical reactions and stochastic switching due to molecular diffusion. Progress in the field of molecular electronics is hampered by the lack of reliable and reproducible data. In this presentation we will present a novel technology to fabricate in high yield large-area metal /self-assembled monolayer / metal junctions(2). The technology is based on the use of a conducting barrier in between the monolayer and the top metal to prevent the formation of shorts, and on processing junctions in photolithographically defined via holes to prevent cross talk. The technology is optimized for alkane(di)thiols to benchmark(3) the electrical transport.