Tunneling Current-Distance Characteristic of Scanning Vibrating Probe / 1-Alkanethiol Self-Assembled Monolayer (SAM) / Au (111) Structure

Abstract

ABSTRACTWe report measurements of the tunneling current – distance (I-d) dependence above alkanethiol self-assembled monolayers (SAMs) on Au (111) substrates with high probe voltage. From the semilogarithmic I-d plots of hexanethiol and octanethiol SAMs, a kink in the tunneling current slopes is clearly observed, which shows the point where the STM tip contacts the end of the SAMs. The conductance decay constants of the vacuum layer and the alkanethiol SAMs are estimated from the tunneling current slopes. We also discuss the contact conductance of alkanethiol SAMs.