Temperature Dependence of Conductance and Plateau Length for Single-Molecule Junctions Formed with Silver Electrodes

The temperature dependence of the conductance and plateau length for the
single-molecule junctions formed with Ag electrodes was investigated by the scanning
tunneling microscope-based break-junction technique. The electrode−electrode gap distance
(GD) was measured by varying temperature as soon as the Ag metal contact was ruptured.
The compressed molecular junction (a tilted molecule) with a small GD at low temperature
showed a higher conductance and longer plateau than the vertically stretched molecular
junction with a large GD at high temperature. However, for the Au electrodes, the GD did
not change by varying temperature, resulting in a constant conductance and plateau. These
results are attributed to a larger diffusion constant of Ag compared to Au, yielding a relatively
temperature-dependent GD for the Ag electrode. This study may advance the understanding
of the electrical and mechanical properties in single-molecule-based devices by varying
temperature