Selective removal of octadecylphosphonic acid (OPA) molecules from their self-assembled monolayers (SAMs) formed on a Si substrate

We show that physisorbed octadecylphosphonic acid (OPA) self-assembled monolayer (SAM) molecules on a Si substrate can be removed by a biased conductive probe tip. Our experimental results suggest that the OPA headgroups are negatively charged and adsorbed on the Si substrate through weak electric charge interaction, allowing one to selectively remove these molecules from their SAMs with an electric field.