Characterization of the tip-loading force-dependent tunneling behavior in alkanethiol metal–molecule–metal junctions by conducting atomic force microscopy

We report on a tip-loading force-dependent tunneling behavior through alkanethiol self-assembled monolayers formed in metal–molecule–metal junctions, using conducting atomic force microscopy. The metal–molecule contacts were formed by placing a conductive tip in a stationary point contact on alkanethiol self-assembled monolayers under a controlled tip-loading force. Current–voltage characteristics in the alkanethiol junctions are simultaneously measured, while varying the loading forces. Tunneling current through the alkanethiol junctions increases and decay coefficient βN decreases, respectively, with increasing tip-loading force, which results from enhanced intermolecular charge transfer in a tilted molecular configuration under the tip-loading effect.