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