An Analysis of Conductive-Probe Atomic Force Microscopy Applied to the Study of Electron Transport Mediating Properties of Self-Assembled Monolayers

We use conductive-probe atomic force microscopy (CP-AFM) and an AFM based nanolithographic technique, called nanografting, to investigate the electron transport mediating properties of self-assembled monolayers (SAMs) of thiols on gold surfaces. We investigated many factors that can influence the measurements, including the contact nature, the roughness of the substrate, the magnitude of the applied normal load, the diversity of different probes, and the tip wearing during the measurements. All these factors influence the measured current value but to a very variable extent. Molecules and impurities adsorbed at the tip/substrate interface are found to be the major cause of the spread of the experimental results. Our work results in the clarification of a series of phenomena to which more attention should be paid in future experimentation.