Variable-temperature study of the transport through a single octanethiol molecule

Abstract

Working on a true molecular level is essential for advances in the field of molecular electronics. Techniques have to be perfected and new approaches have to be developed in order to characterize the properties of a single molecule. In this work we report temperature-dependent transport studies of a single octanethiol molecule trapped between the apex of a scanning tunneling microscope tip and a substrate. At each temperature the molecule is brought into contact by decreasing the gap between tip and substrate in a controlled way. At a positive sample bias the molecule jumps into contact upon approaching the substrate by $0.16\ifmmode\pm\else\textpm\fi{}0.01$ nm with respect to a fixed reference point defined by a sample bias of $+$1.5 V and a tunneling current of 0.5 nA. The conductance of octanethiol is temperature independent, demonstrating that either tunneling or ballistic transport is the main transport mechanism.