Effect of end groups on contact resistance of alkanethiol based metal–molecule–metal junctions using current sensing AFM

Tuning the charge transport through a metal–molecule–metal junction by changing the interface properties is widely studied and is of paramount importance for applications in molecular electronic devices. We used current sensing atomic force microscopy (CSAFM) as a tool to study the contact resistance of metal–molecule–metal (MmM) junctions formed by sandwiching self-assembled monolayers (SAMs) of alkanethiols with various end groups (–CH3, –OH and –NH2) between Au(1 1 1) substrates and Au coated AFM tips. The effect of interface chemistry on charge transport through such SAMs with varying end groups was studied in an inert, non-polar liquid (hexadecane) environment.We find that the contact resistances of these MmM junctions vary significantly based on the end group chemistry of the molecules