A simple micromachining approach to testing nanoscale metal–self-assembledmonolayer–metal junctions

Abstract

We present a ‘flip chip’ technique for testing electronic self-assembledmonolayers (SAMs). Metal–SAM–metal junctions with contact areas of approximately(25 nm)2 and smaller have been created and tested. While the approach is similar in spirit toconductive atomic force microscope measurements, it requires only straightforward opticallithography to create the test chips and a simple gravitational-force flexure to close thejunction with sub-angstrom scale precision. The junction is formed in a vertical manner,in which the SAM is grown on one or both metal electrodes, and the circuit isclosed via the pressure-induced flexing of one chip into another. This methodof creating a junction is rapid and facilitates multiple measurements per chipset. We have investigated the electrical transport characteristics of a variety ofSAMs using this technique, including aliphatic alkanethiols and aromatic dithiols.Results are consistent with junction contact areas , and elucidate information regarding the role of pressure and defects on SAMtransport.