Electrical Contacts to Molecular Layers by Nanotransfer Printing

We introduce a novel approach, nanotransfer printing (nTP), for fabricating top-contact electrodes in molecular junctions. To evaluate the nature of electrical contact, we conducted current-voltage and photoresponse experiments on diodes that are comprised of Au top electrodes on 1,8-octanedithiol coated n+ GaAs substrates. Results show that the method in which the Au top contact electrodes are fabricated strongly affects transport mechanisms in these molecular junctions. Electrical transport in nTP devices occurs through the 1,8-octanedithiol molecules while conduction in devices fabricated by conventional evaporation of Au onto the molecular layer is dominated by direct Au/GaAs contacts. Thus, nTP is a promising new method for making reliable electrical contacts in molecular electronic devices.